CN101369553B - High density plasma gap filling method for reducing gas phase nucleation defects - Google Patents

Abstract

A high density plasma gap filling method for reducing gas phase nucleation defects, comprising the steps of: first, a substrate having a trench therein is provided in a reaction chamber. Then, a first deposition step is performed to partially fill the trench with a dielectric material. An etching step is then performed to partially remove the dielectric material in the trench. Then, a second deposition step is carried out, the dielectric material is partially filled in the groove, wherein the reaction gas used in the second deposition step comprises carrier gas, oxygen-containing gas, silicon-containing gas and hydrogen-containing gas, and the silicon-containing gas and the hydrogen-containing gas are loaded into the reaction chamber after the carrier gas and the oxygen-containing gas are loaded into the reaction chamber and the radio frequency power supply is started for a period of time.

Description

High Density Plasma Trench Filling Method for Reducing Gas Phase Nucleation Defects

technical field

The invention relates to a semiconductor process, and in particular to a high-density plasma trench filling method for reducing gas-phase nucleation defects.

Background technique

With the advancement of semiconductor technology, the size of components is also continuously reduced and enters the field of deep sub-micron, even finer size range. Therefore, the isolation between components becomes very important to prevent the occurrence of short circuit between adjacent components. Generally speaking, an isolation layer is added between components, and the more common technique is Local Oxidation of Silicon (LOCOS). However, the partial silicon oxidation method still has many disadvantages, including the related problems derived from the generation of stress, and the formation of the bird's beak around the isolation structure and so on. Among them, the formation of the bird's beak region is the most unfavorable to the improvement of component integration. Therefore, the more commonly used method today is the shallow trench isolation (Shallow Trench Isolation, STI) process.

The manufacturing method of the shallow trench isolation structure is mainly to form a trench in the substrate, and then fill the trench with a dielectric material as an isolation layer. Generally speaking, the industry currently uses high density plasma (High Density Plasma, HDP) chemical vapor deposition (Chemical Vapor Deposition, CVD) to fill the isolation layer (gapfill), and the dielectric material used is Silicon dioxide (Silicon Dioxide, SiO2). However, when the process line width shrinks, the aspect ratio (Aspect Ratio, AR) of the trench depth to width will increase accordingly. Therefore, voids are likely to be generated when the isolation layer is filled, and the difficulty is thus increased. Therefore, in the shallow trench isolation structure filling process of 90nm and sub-90nm, a multi-step filling process such as deposition-etch-deposition (Deposition-Etch-Deposition, DED) has been developed to obtain high-depth Shallow Trench Isolation (STI) with wide aspect ratio (AR) and no voids.

However, in the above-mentioned multi-step filling process, its disadvantage is that when the etching step is switched to the deposition step, the plasma is unstable due to the switching of the reactive gas, so a large number of gas phase nucleation (GPN) defects will be generated. Vapor-phase nucleation defects not only cause protruding shallow trench isolation structures and scratching products, thereby reducing the reliability of components, but also easily attach to the reaction chamber wall and become a source of pollution. In particular, today's semiconductor technology has entered the nanometer process, and the tolerance for pollution caused by gas-phase nucleation defects is even lower.

Contents of the invention

The purpose of the present invention is to provide a high-density plasma trench filling method that reduces gas-phase nucleation defects. In the multi-step filling process of trenches, the phenomenon of gas-phase nucleation in the reaction chamber is alleviated, thereby reducing gas-phase nucleation defects. .

The invention proposes a high-density plasma trench filling method for reducing gas-phase nucleation defects, which includes the following steps. Firstly, a substrate is provided in the reaction chamber, and the substrate has grooves therein. Then, a first deposition step is performed to partially fill the trenches with dielectric material. Next, an etching step is performed to partially remove the dielectric material in the trench. Afterwards, a second deposition step is performed to partially fill the trench with a dielectric material, wherein the reaction gas used in the second deposition step includes a carrier gas, an oxygen-containing gas, a silicon-containing gas, and a hydrogen-containing gas, and the Loading the carrier gas and the oxygen-containing gas into the reaction chamber and turning on the radio frequency power for a period of time, and then loading the silicon-containing gas and the hydrogen-containing gas into the reaction chamber.

According to the high-density plasma trench filling method for reducing gas phase nucleation defects described in the embodiment of the present invention, the method further includes repeating the etching step and the second deposition step until the dielectric material fills the trench.

According to the high-density plasma trench filling method for reducing gas-phase nucleation defects described in an embodiment of the present invention, the reaction gas used in the first deposition step includes a carrier gas, an oxygen-containing gas, a silicon-containing gas, and a hydrogen-containing gas, and After loading the carrier gas and the oxygen-containing gas into the reaction chamber and turning on the RF power for a period of time, the silicon-containing gas and the hydrogen-containing gas are loaded into the reaction chamber.

According to the high-density plasma trench filling method for reducing gas-phase nucleation defects described in the embodiments of the present invention, the carrier gas may be an inert gas.

According to the high-density plasma trench filling method for reducing gas-phase nucleation defects described in the embodiment of the present invention, in the above-mentioned second deposition step, it also includes loading carrier gas and oxygen-containing gas into the reaction chamber and turning on the radio frequency power supply for a period of After a period of time, the silicon-containing gas is loaded first, and then the hydrogen-containing gas is loaded into the reaction chamber.

According to the high-density plasma trench filling method for reducing gas-phase nucleation defects described in the embodiments of the present invention, in the second deposition step, after the silicon-containing gas is loaded into the reaction chamber, the hydrogen-containing gas is loaded into the reaction chamber The previous time interval in the chamber was greater than or equal to 1 second.

According to the high-density plasma trench filling method for reducing gas-phase nucleation defects described in the embodiments of the present invention, in the second deposition step, after the silicon-containing gas is loaded into the reaction chamber, the hydrogen-containing gas is loaded into the reaction chamber The previous time interval in the chamber was 1 second to 4 seconds.

According to the high-density plasma trench filling method for reducing gas-phase nucleation defects described in the embodiments of the present invention, in the above-mentioned second deposition step, the hydrogen-containing gas is loaded into the reaction chamber in a manner of increasing flow rate.

According to the high-density plasma trench filling method for reducing gas-phase nucleation defects described in the embodiments of the present invention, the silicon-containing gas may be silane gas.

According to the high-density plasma trench filling method for reducing gas-phase nucleation defects described in the embodiments of the present invention, the reaction gas used in the etching step includes fluorine-containing compounds and hydrogen-containing gases.

According to the high-density plasma trench filling method for reducing gas-phase nucleation defects described in the embodiments of the present invention, the above-mentioned fluorine-containing compounds include nitrogen fluoride, halothane compounds, and sulfur fluoride.

In the above-mentioned high-density plasma trench filling method for reducing gas-phase nucleation defects, when switching from the etching step to the second deposition step, after loading the carrier gas and oxygen-containing gas in the reaction chamber for a period of time, turn on the radio frequency power to make the The plasma in the reaction chamber reaches a stable state, and then silicon-containing gas and hydrogen-containing gas are introduced. Therefore, the deposition reaction can be carried out in a stable state, and the gas phase nucleation defects can be reduced. Moreover, since the etching step and the second deposition step are carried out at the same position in the same reaction machine. Therefore, the process can be effectively simplified and the process time can be shortened.

The invention proposes a high-density plasma trench filling method for reducing gas-phase nucleation defects, which includes the following steps. First, a substrate is provided, and the substrate has grooves therein. Next, a first deposition step is performed to partially fill the trench with dielectric material. Then, an etching step is performed to partially remove the dielectric material in the trench. Afterwards, a second deposition step is performed to partially fill the trench with a dielectric material, wherein the reaction gas used in the second deposition step includes a carrier gas, an oxygen-containing gas, a silicon-containing gas, and a hydrogen-containing gas, and the Loading the carrier gas, oxygen-containing gas, and silicon-containing gas into the reaction chamber and turning on the radio frequency power for a period of time, and then loading the hydrogen-containing gas into the reaction chamber.

According to the high-density plasma trench filling method for reducing gas phase nucleation defects described in the embodiment of the present invention, the method further includes repeating the etching step and the second deposition step until the dielectric material fills the trench.

According to the high-density plasma trench filling method for reducing gas-phase nucleation defects described in an embodiment of the present invention, the reaction gas used in the first deposition step includes a carrier gas, an oxygen-containing gas, a silicon-containing gas, and a hydrogen-containing gas, and After loading the carrier gas, oxygen-containing gas, and silicon-containing gas into the reaction chamber and turning on the radio frequency power for a period of time, the hydrogen-containing gas is then loaded into the reaction chamber.

According to the high-density plasma trench filling method for reducing gas-phase nucleation defects described in the embodiments of the present invention, the carrier gas may be an inert gas.

According to the high-density plasma trench filling method for reducing gas-phase nucleation defects described in the embodiments of the present invention, the silicon-containing gas may be silane gas.

According to the high-density plasma trench filling method for reducing gas-phase nucleation defects described in the embodiments of the present invention, the reaction gas used in the etching step includes fluorine-containing compounds and hydrogen-containing gases.

According to the high-density plasma trench filling method for reducing gas-phase nucleation defects described in the embodiments of the present invention, the above-mentioned fluorine-containing compounds include nitrogen fluoride, halothane compounds, and sulfur fluoride.

According to the high-density plasma trench filling method for reducing gas-phase nucleation defects described in the embodiments of the present invention, in the second deposition step, after the silicon-containing gas is loaded into the reaction chamber, the hydrogen-containing gas is loaded into the reaction chamber The previous time interval in the chamber was greater than or equal to 1 second.

According to the high-density plasma trench filling method for reducing gas-phase nucleation defects described in the embodiments of the present invention, in the second deposition step, after the silicon-containing gas is loaded into the reaction chamber, the hydrogen-containing gas is loaded into the reaction chamber The previous time interval in the chamber was 1 second to 4 seconds.

According to the high-density plasma trench filling method for reducing gas-phase nucleation defects described in the embodiments of the present invention, in the above-mentioned second deposition step, the hydrogen-containing gas is loaded into the reaction chamber in a manner of increasing flow rate.

In the above-mentioned high-density plasma trench filling method for reducing gas-phase nucleation defects, when switching from the etching step to the second deposition step, the reaction chamber is loaded with carrier gas, oxygen-containing gas, and silicon-containing gas and the radio frequency is turned on. The power supply passes through for a period of time to make the plasma in the reaction chamber reach a stable state, and then introduce the hydrogen-containing gas. Since the silicon-containing gas has been pre-dissociated completely in the reaction chamber, the deposition reaction can be carried out in a stable state, and the gas-phase nucleation defects can be reduced. Moreover, since the etching step and the second deposition step are carried out at the same position in the same reaction machine. Therefore, the process can be effectively simplified and the process time can be shortened.

The invention proposes a high-density plasma trench filling method for reducing gas-phase nucleation defects, which includes the following steps. First, a substrate is provided, and the substrate has grooves therein. Next, a first deposition step is performed to partially fill the trench with dielectric material. Then, an etching step is performed to partially remove the dielectric material in the trench. Then, a second deposition step is performed to partially fill the trench with a dielectric material, wherein the reaction gas used in the second deposition step includes a carrier gas, an oxygen-containing gas, and a silicon-containing gas. Then a third deposition step is performed to partially fill the trench with dielectric material, wherein the reaction gases used in the third deposition step include carrier gas, oxygen-containing gas, silicon-containing gas and hydrogen-containing gas.

According to the high density plasma trench filling method for reducing gas phase nucleation defects described in the embodiment of the present invention, the method further includes repeating the etching step, the second deposition step and the third deposition step until the dielectric material fills the trench.

According to the high-density plasma trench filling method for reducing gas-phase nucleation defects described in the embodiments of the present invention, the reaction gases used in the first deposition step include carrier gas, oxygen-containing gas, silicon-containing gas, and hydrogen-containing gas.

According to the high-density plasma trench filling method for reducing gas-phase nucleation defects described in the embodiments of the present invention, the carrier gas may be an inert gas.

According to the high-density plasma trench filling method for reducing gas-phase nucleation defects described in the embodiments of the present invention, the silicon-containing gas may be silane gas.

According to the high-density plasma trench filling method for reducing gas-phase nucleation defects described in the embodiments of the present invention, the reaction gas used in the etching step includes fluorine-containing compounds and hydrogen-containing gases.

According to the high-density plasma trench filling method for reducing gas-phase nucleation defects described in the embodiments of the present invention, the above-mentioned fluorine-containing compounds include nitrogen fluoride, halothane compounds, and sulfur fluoride.

In the above-mentioned high-density plasma trench filling method for reducing gas-phase nucleation defects, the second deposition step is provided between the etching step and the third deposition step. A second deposition step is used to bring the plasma in the reaction chamber to a steady state. Therefore, after directly switching from the second deposition step to the third deposition step, the third deposition step can be performed in a stable state, thereby reducing gas phase nucleation defects.

In order to make the above and other objects, features and advantages of the present invention more comprehensible, preferred embodiments will be described in detail below together with the accompanying drawings.

Description of drawings

FIG. 1 is a flow chart of a high-density plasma trench filling method for reducing gas-phase nucleation defects according to a first embodiment of the present invention.

2A-2E are cross-sectional views of a process for forming a trench isolation structure according to an embodiment of the present invention.

FIG. 3 is a flow chart of a high-density plasma trench filling method for reducing gas-phase nucleation defects according to a second embodiment of the present invention.

FIG. 4 is a flowchart of a high-density plasma trench filling method for reducing gas-phase nucleation defects according to a third embodiment of the present invention.

FIG. 5 is a graph showing the relationship between process time and high frequency radio frequency reflected power.

FIG. 6 is a graph showing the relationship between process time and reaction chamber pressure.

[Description of main component symbols]

200: base

202: Groove

204: pad oxide layer

206: mask layer

208: Dielectric materials

210: opening

212: Overhang

D1: first deposition step

D2: Second deposition step

E: Etching step

T1: first switching step

T2: second switching step

S100, S102, S104, S106, S108, S300, S302, S304, S306, S308, S400, S402, S404, S406, S408, S410: steps

Detailed ways

first embodiment

FIG. 1 is a flow chart of a high-density plasma trench filling method for reducing gas-phase nucleation defects according to a first embodiment of the present invention. 2A-2E are cross-sectional views of a process for forming a trench isolation structure according to an embodiment of the present invention. In the following embodiments, the formation of a trench isolation structure is taken as an example for illustration. Of course, the high-density plasma trench filling method for reducing gas-phase nucleation defects of the present invention can also be applied to the formation of an interlayer dielectric layer between patterns of conductive layers such as gate electrode layers or metal layers. craft.

Please refer to FIG. 1 and FIG. 2A at the same time. First, step S100 is performed to provide a substrate 200 in the reaction chamber, and the substrate 200 has a groove 202 therein. The material of the substrate 200 is, for example, a silicon substrate. The method of forming the trench 202 is as follows. First, a comprehensive pad oxide layer 204 and a mask layer 206 are sequentially formed on the substrate 200 . The material of the pad oxide layer 204 is, for example, silicon oxide, and its formation method is, for example, a thermal oxidation process. The material of the mask layer 206 is, for example, a silicon nitride layer. The mask layer 206 is formed by, for example, performing a chemical vapor deposition process.

Next, the mask layer 206 and the pad oxide layer 204 are patterned to expose the surface of the substrate 200 where the trench 202 is to be formed. Then, using the patterned mask layer 206 and the pad oxide layer 204 as an etching mask, the substrate 200 is etched to form the trench 202 . The reaction chamber is, for example, a reaction chamber of a high-density plasma etching tool.

Referring to FIG. 1 and FIG. 2B at the same time, step S102 is performed to perform a first deposition step to partially fill the trench 202 with a dielectric material 208 . The dielectric material 208 is formed by, for example, a high-density plasma chemical vapor deposition process, an atmospheric pressure (AP) or a sub-atmospheric pressure (SA) chemical vapor deposition process. If the dielectric material 208 is silicon oxide, in the first deposition step, the reaction gas used includes carrier gas, oxygen-containing gas such as oxygen (O ₂ ), ozone (O ₃ ), nitrogen monoxide (NO), Dinitrogen oxide (N ₂ O) and its mixture, silicon-containing gas and hydrogen-containing gas are, for example, hydrogen (H ₂ ) or its isotopes (deuterium, tritium), ammonia (NH ₃ ). The carrier gas includes inert gases such as argon (Ar), helium (He), neon (Ne), krypton (Kr), xenon (Xe), nitrogen (N ₂ ) and mixtures thereof. Silicon-containing gas includes silane gas (in the present invention, silane gas is a general term for silane compounds and derivatives thereof), such as monosilane (SiH ₄ ), disilane (Si ₂ H ₆ ), trisilane (Si ₃ H ₈ ), tetrasilane (tetrailane, Si ₄ H ₁₀ ), tetraethoxysilane (tetraethylorthosilicate, TEOS), tetramethylcyclotetrasiloxane (tetramethyl-cyclotetrasiloxane, TMCTS), octamethylcyclotetrasiloxane (octamethyl-cyclotetrasiloxane , OMCTS), methyl-silane, dimethyl-silane, trimethylsilane, tetramethylsilane, tetramethyldisiloxane (tetramethyl-disiloxane, TMDSO), tetramethyl-diethoxyl-disiloxane (TMDDSO), dimethyl-diethoxyl-silane (DMDMS) and mixtures thereof.

In addition to the above-mentioned gases, the reaction gas may also contain other dopant gases according to the dielectric material 208 to be deposited. For example, if the dielectric material 208 is phosphosilicate glass (phosphosilicateGlass, PSG) or borophosphosilicate glass (BPSG), then the reaction gas further contains phosphine (PH ₃ ) and/or hexahydrogen Boron (B ₂ H ₆ ) or triethylborate (TEB) and/or triethylphosphate (TEPO). If the dielectric material 208 is nitrogen-containing silicon oxide, the reaction gas further contains nitrogen (N ₂ ), ammonia (NH ₃ ), nitrogen monoxide (NO), nitrous oxide (N ₂ O) and mixture.

Moreover, as shown in FIG. 2B , the dielectric material 208 does not fill the trench 202 , but an opening 210 is formed, and an overhang 212 is formed at a corner of the mask layer 206 . The overhang 212 makes it difficult for the dielectric material 208 to fill into the trench 202 .

Referring to FIG. 1 and FIG. 2C at the same time, step S104 is performed to perform an etching step to partially remove the dielectric material 208 in the trench 202 to remove the overhang 212 and increase the width of the opening 210 . The reactive gases used in the etching step include fluorine-containing compounds and hydrogen-containing gases. Fluorine-containing compounds are, for example, nitrogen fluoride, halothane compounds, and sulfur fluoride.

Referring to FIG. 1 and FIG. 2D at the same time, step S106 is performed to perform a second deposition step to partially fill the trench 202 with a dielectric material 208 . The reaction gas used in the second deposition step includes carrier gas, oxygen-containing gas, silicon-containing gas and hydrogen-containing gas, and after loading the carrier gas and oxygen-containing gas into the reaction chamber and turning on the RF power for a period of time, then Load silicon-containing gas and hydrogen-containing gas into the reaction chamber. This second deposition step follows the etching step described above. When switching from the etching step to the second deposition step, if the reaction gases (carrier gas, oxygen-containing gas, silicon-containing gas, and hydrogen-containing gas) are simultaneously loaded into the reaction chamber, since the plasma inside the reaction chamber is in an unstable state, so that the radio frequency reflectance power (RF reflectance power) is increased, resulting in the incomplete dissociation nucleation reaction of the silicon-containing gas and easy to form a silicon-containing gas cluster (cluster). Moreover, the hydrogen-containing gas reacts with the oxygen-containing gas to generate water vapor, and the silicon-containing gas cluster reacts with the generated water vapor, resulting in the formation of gas phase nucleation defects and attaching to the substrate. In this embodiment, when switching from the etching step to the second deposition step, the reaction chamber is loaded with carrier gas and oxygen-containing gas for a period of time to remove the residual gas left by the etching step (equivalent to the cleaning step) , and turn on the radio frequency power supply to make the plasma in the reaction chamber reach a stable state, and then introduce silicon-containing gas and hydrogen-containing gas. The deposition reaction can be carried out in a stable state, and the gas phase nucleation defects can be reduced.

In the second deposition step, the dielectric material 208 is formed by, for example, a high-density plasma chemical vapor deposition process, an atmospheric pressure (AP) or a sub-atmospheric pressure (SA) chemical vapor deposition process. If the dielectric material 208 is silicon oxide, in the second deposition step, the reaction gas used includes carrier gas, oxygen-containing gas, such as oxygen (O ₂ ), ozone (O ₃ ), nitrogen monoxide (NO), Nitrous oxide (N ₂ O) and its mixture, silicon-containing gas and hydrogen-containing gas are, for example, hydrogen (H ₂ ) or its isotopes (deuterium, tritium), ammonia (NH ₃ ). The carrier gas includes inert gases such as argon (Ar), helium (He), neon (Ne), krypton (Kr), xenon (Xe), nitrogen (N2) and mixtures thereof. Silicon-containing gases include silane gases such as monosilane, disilane, trisilane, tetrasilane, tetraethoxysilane, tetramethylcyclotetraoxosilane, octamethylcyclotetraoxosilane, methylsilane, dimethyl methylsilane, trimethylsilane, tetramethylsilane, tetramethyldisiloxane, tetramethyldiethoxydisiloxane, dimethyldiethoxysilane and mixtures thereof.

In addition to the above-mentioned gases, the reaction gas may also contain other dopant gases according to the dielectric material 208 to be deposited. For example, if the dielectric material 208 is phosphosilicate glass or borophosphosilicate glass, the reaction gas contains phosphine and/or diboron hexahydride or triethylborate (TEB) and/or phosphoric acid Triethylphosphate (TEPO). If the dielectric material 208 is nitrogen-containing silicon oxide, the reaction gas includes nitrogen, ammonia, nitrogen monoxide, nitrous oxide and mixtures thereof.

Please refer to FIG. 1 and FIG. 2E at the same time, proceed to step 108 , repeat step S104 and step S106 until the dielectric material 208 fills the trench 202 . In this step, the etching step and the deposition step are repeated until the dielectric material fills the trench. Similarly, when switching from the etching step to the deposition step, after loading the carrier gas and oxygen-containing gas in the reaction chamber for a period of time, turn on the radio frequency power supply to make the plasma in the reaction chamber reach a stable state, and then introduce the silicon-containing gas and Hydrogen-containing gas. The deposition reaction can be carried out in a stable state, and the gas phase nucleation defects can be reduced.

It should be noted that the reaction gases used in the first deposition step and the second deposition step may be the same or different. For example, the reaction gas used in the first deposition step, the carrier gas can be helium or nitrogen, the silicon-containing gas can be tetraethoxysilane, and the oxygen-containing gas can be oxygen or ozone. For the reaction gas used in the second deposition step, the carrier gas can be helium or nitrogen, the silicon-containing gas can be silane, the oxygen-containing gas can be oxygen, and the hydrogen-containing gas can be hydrogen or its isotopes (deuterium, tritium).

Of course, in the second deposition step, it is also possible to first load the carrier gas and the oxygen-containing gas into the reaction chamber, and after turning on the RF power for a period of time, first load the silicon-containing gas, and then load the hydrogen-containing gas into the reaction chamber . Moreover, the time interval between loading the silicon-containing gas into the reaction chamber and before loading the hydrogen-containing gas into the reaction chamber is greater than or equal to 1 second, preferably 1 second to 4 seconds. In addition, in the second deposition step, the hydrogen-containing gas can also be loaded into the reaction chamber in a manner of increasing flow rate, which has the advantage of ensuring that the hydrogen-containing gas and silicon-containing gas do not occur before the complete dissociation of the silicon-containing gas begins. The reaction of oxygen-containing gas to generate water vapor produces a large number of gas-phase nucleation defects. In the first embodiment, the radio frequency power source is, for example, a high frequency radio frequency power source. Moreover, the low-frequency RF power can be continuously turned on throughout the process.

In the first embodiment of the present invention, when switching from the etching step to the deposition step, the reaction chamber is loaded with carrier gas and oxygen-containing gas for a period of time, and then the radio frequency power is turned on to make the plasma in the reaction chamber reach a stable state. , and then introduce silicon-containing gas and hydrogen-containing gas. Therefore, the deposition reaction can be carried out in a stable state of the plasma, and the gas phase nucleation defects can be reduced. Moreover, since the etching step and the deposition step are, for example, performed at the same position in the same reaction machine. Therefore, the process can be effectively simplified and the process time can be shortened.

Moreover, in the first embodiment of the present invention, the second deposition step can also be carried out in the order of firstly loading the carrier gas and the oxygen-containing gas, then loading the silicon-containing gas, and then loading the hydrogen-containing gas. The effect of reducing gas phase nucleation defects is achieved.

second embodiment

FIG. 3 is a flow chart of a high-density plasma trench filling method for reducing gas-phase nucleation defects according to a second embodiment of the present invention. In the following description, only the differences between this embodiment and the first embodiment will be described in detail.

Referring to FIG. 3 , step S300 is firstly performed to provide a substrate in the reaction chamber. The substrate has grooves in it.

Then, proceed to step S302 , perform a first deposition step, and partially fill the trench with a dielectric material. The method for forming the dielectric material is, for example, performing a high-density plasma chemical vapor deposition process. In the first deposition step, the reaction gases used include carrier gas, oxygen-containing gas, silicon-containing gas and hydrogen-containing gas. The carrier gas, oxygen-containing gas, silicon-containing gas, and hydrogen-containing gas used in the first deposition step are the same as those in the first embodiment.

Next, step S304 is performed to perform an etching step to partially remove the dielectric material in the trench. The reactive gases used in this etching step include fluorine-containing compounds and hydrogen-containing gases. The fluorine-containing compound and the hydrogen-containing gas used in this embodiment are the same as those in the first embodiment.

Then, proceed to step S306 , perform a second deposition step, and partially fill the trench with a dielectric material. The reaction gases used in the second deposition step include carrier gas, oxygen-containing gas, silicon-containing gas, and hydrogen-containing gas, and after loading the carrier gas, oxygen-containing gas, and silicon-containing gas into the reaction chamber and turning on the radio frequency power After a period of time, the hydrogen-containing gas is loaded into the reaction chamber. The time interval between loading the silicon-containing gas into the reaction chamber and before loading the hydrogen-containing gas into the reaction chamber is, for example, greater than or equal to 1 second, preferably 1 second to 4 seconds. In this embodiment, when switching from the etching step to the second deposition step, the reaction chamber is loaded with carrier gas, oxygen-containing gas, and silicon-containing gas and the RF power is turned on for a period of time to make the plasma in the reaction chamber After reaching a steady state, the hydrogen-containing gas is introduced. Since the silicon-containing gas has been completely dissociated in the reaction chamber in advance, the deposition reaction can be carried out in a stable state of the plasma, and the gas phase nucleation defects can be reduced. The carrier gas, oxygen-containing gas, silicon-containing gas, and hydrogen-containing gas used in the second deposition step are the same as those in the first embodiment.

Afterwards, step S308 is performed, and step S304 and step S306 are repeated until the dielectric material fills the trench. In this step, the etching step and the deposition step are repeated until the dielectric material fills the trench. Similarly, when switching from the etching step to the deposition step, first load the carrier gas, oxygen-containing gas and silicon-containing gas in the reaction chamber and turn on the radio frequency power for a period of time, so that the plasma in the reaction chamber reaches a stable state, Then introduce hydrogen-containing gas. The deposition reaction can be carried out in a stable state, and the gas phase nucleation defects can be reduced. In this embodiment, the reaction gases used in the first deposition step and the second deposition step may be the same or different, such as the first embodiment. In the second embodiment, the radio frequency power source is, for example, a high frequency radio frequency power source. Moreover, the low-frequency RF power can be continuously turned on throughout the process.

In the second embodiment of the present invention, when switching from the etching step to the deposition step, the carrier gas, oxygen-containing gas, and silicon-containing gas are loaded into the reaction chamber and the radio frequency power is turned on for a period of time to make the reaction chamber After the plasma reaches a steady state, the hydrogen-containing gas is introduced. Since the silicon-containing gas has been pre-dissociated completely in the reaction chamber, the deposition reaction can be carried out in a stable state, and the gas-phase nucleation defects can be reduced. Moreover, since the etching step and the deposition step are, for example, performed at the same position in the same reaction machine. Therefore, the process can be effectively simplified and the process time can be shortened.

third embodiment

FIG. 4 is a flowchart of a high-density plasma trench filling method for reducing gas-phase nucleation defects according to a third embodiment of the present invention. In the following description, only the differences between this embodiment and the first embodiment and the second embodiment will be described in detail.

Referring to FIG. 4 , step S400 is firstly performed to provide a substrate in the reaction chamber. The substrate has grooves in it.

Then, proceed to step S402 , perform a first deposition step, and partially fill the trench with a dielectric material. The method for forming the dielectric material is, for example, performing a high-density plasma chemical vapor deposition process. In the first deposition step, the reaction gases used include carrier gas, oxygen-containing gas, silicon-containing gas and hydrogen-containing gas. The carrier gas, oxygen-containing gas, silicon-containing gas, and hydrogen-containing gas used in the first deposition step are the same as those in the first embodiment.

Next, step S404 is performed to perform an etching step to partially remove the dielectric material in the trench. The reactive gases used in this etching step include fluorine-containing compounds and hydrogen-containing gases. The fluorine-containing compound and the hydrogen-containing gas used in this embodiment are the same as those in the first embodiment.

Then, proceed to step S406 , perform a second deposition step, and partially fill the trench with a dielectric material. The reaction gases used in the second deposition step include carrier gas, oxygen-containing gas and silicon-containing gas. The carrier gas, oxygen-containing gas, and silicon-containing gas used in the second deposition step are the same as those in the first embodiment. Since no hydrogen-containing gas is loaded into the reaction chamber when switching from the etching step to the second deposition step, the reaction gas will not produce a violent reaction, but only a thin layer of dielectric material will be formed on the surface of the substrate. Moreover, no hydrogen-containing gas is loaded in the reaction chamber, and moisture will not be generated in the reaction chamber. In addition, the plasma in the reaction chamber will reach a steady state.

Then, proceed to step S408 , perform a third deposition step on the substrate, and partially fill the trench with a dielectric material. The reaction gases used in the third deposition step include carrier gas, oxygen-containing gas, silicon-containing gas and hydrogen-containing gas. Since the plasma in the reaction chamber has reached a stable state in the second deposition step, after directly switching from the second deposition step to the third deposition step, the third deposition step can be carried out in a stable state of the plasma, which can reduce the Gas phase nucleation defects. The carrier gas, oxygen-containing gas, silicon-containing gas, and hydrogen-containing gas used in the third deposition step are the same as those in the first embodiment.

Afterwards, step S410 is performed, and steps S404 to S408 are repeated until the dielectric material fills the trench. In the step S410, the etching step, the second deposition step, and the third deposition step are repeated until the dielectric material fills the trench.

In the third embodiment of the present invention, since the second deposition step is provided between the etching step and the third deposition step. A second deposition step is used to bring the plasma in the reaction chamber to a steady state. Therefore, after directly switching from the second deposition step to the third deposition step, the third deposition step can be performed in a stable state, thereby reducing gas phase nucleation defects.

It should be noted that the first deposition step, the etching step, the second deposition step and the third deposition step are, for example, carried out in the same reaction machine. Therefore, the process can be effectively simplified and the process time can be shortened.

In addition, the first deposition steps of the above-mentioned first embodiment to the third embodiment can also be performed in the same way as the second deposition steps of the first embodiment and the second embodiment. That is, in the first deposition step, the reaction chamber is loaded with carrier gas and oxygen-containing gas for a period of time, then the RF power is turned on to make the plasma in the reaction chamber reach a stable state, and then silicon-containing gas and hydrogen-containing gas are loaded. gas. Alternatively, the reaction chamber is loaded with carrier gas, oxygen-containing gas and silicon-containing gas, and the radio frequency power is turned on for a period of time, so that the plasma in the reaction chamber reaches a stable state, and then the hydrogen-containing gas is introduced.

The following is based on the experimental example (loading carrier gas, oxygen-containing gas and silicon-containing gas for a period of time, and then loading hydrogen-containing gas.) and known examples (all reaction gases are loaded at the same time at the beginning of the process) to prove this The invention can indeed reduce the occurrence of gas phase nucleation defects.

FIG. 5 is a graph showing the relationship between the process time and the reflected power of high frequency radio frequency. FIG. 6 is a graph showing the relationship between process time and reaction chamber pressure. In FIG. 5 and FIG. 6, the process time is divided into five intervals, that is, the first deposition step D1, the first switching step T1, the etching step E, the second switching step T2, and the second deposition step D2. In FIG. 5 and FIG. 6, the solid line shows the experimental example of this invention, and the dotted line shows the known example. Moreover, each preferred process parameter is as shown in Table 1.

Table I

 Process parameters The first deposition step D1 Etching step E Second deposition step D2 SiH₄ flow rate (sccm) 80 0 80 O₂ flow rate (sccm) 144 0 144 He flow rate (sccm) 300 200 300 H₂ flow rate (sccm) 400 500 400 NF₃ flow rate (sccm) 0 200 0 Low frequency power (W) 5000 2200 5000 High frequency power (W) 3600 1500 3600 Process pressure (mTorr) 5.5 7 5.5 Process temperature (℃) 534 400 534

As shown in FIG. 5 and FIG. 6 , in the known example (as shown by the dotted line), in the first switching step T1 and the second switching step T2 , the high-frequency radio frequency reflected power will increase. Especially in the second switching step T2 between the etching step E and the second deposition step D2 the radio-frequency reflected power is particularly high. This is because the plasma inside the reaction chamber is in an unstable state, so that the radio frequency reflectance power is increased, resulting in incomplete dissociation and nucleation reactions of the silicon-containing gas and easy formation of silicon-containing gas clusters. Also, the hydrogen-containing gas reacts with the oxygen-containing gas to form water. Then, silicon-containing gas clusters react with water, resulting in the formation of gas-phase nucleation defects.

And the high-frequency radio frequency reflection of the second switching step T2 between the etching step E and the second deposition step D2 in the experimental example (as shown by the solid line) of the high-density plasma trench filling method for reducing gas-phase nucleation defects of the present invention The power is significantly reduced, which can reduce gas phase nucleation defects.

In summary, the high-density plasma trench filling method for reducing gas-phase nucleation defects of the present invention, when switching from the etching step to the deposition step, after the plasma in the reaction chamber reaches a stable state, after introducing the hydrogen-containing gas ( or both silicon-containing gas and hydrogen-containing gas). Therefore, the deposition reaction can be carried out in a stable state of the plasma, and the gas phase nucleation defects can be reduced. Moreover, since the etching step and the deposition step are carried out at the same position in the same reaction machine. Therefore, the process can be effectively simplified and the process time can be shortened.

Claims (28)

1. A high-density plasma trench filling method for reducing gas-phase nucleation defects, comprising: (a) providing a substrate in the reaction chamber, the substrate having grooves therein; (b) performing a first deposition step to partially fill the trench with dielectric material; (c) performing an etching step to partially remove the dielectric material in the trench; and (d) performing a second deposition step, partially filling the trench with the dielectric material, wherein the reaction gas used in the second deposition step includes carrier gas, oxygen-containing gas, silicon-containing gas, and hydrogen-containing gas gas, and after loading the carrier gas and the oxygen-containing gas into the reaction chamber and turning on the radio frequency power supply for a period of time, then load the silicon-containing gas and the hydrogen-containing gas into the reaction chamber. 2. The high density plasma trench filling method for reducing gas phase nucleation defects as claimed in claim 1, further comprising repeating step (c) and step (d) until the dielectric material fills the trench. 3. The high-density plasma trench filling method for reducing gas-phase nucleation defects as claimed in claim 1, wherein the reaction gas used in the first deposition step comprises the carrier gas, the oxygen-containing gas, the silicon-containing gas and The hydrogen-containing gas, and after loading the carrier gas and the oxygen-containing gas into the reaction chamber and turning on the radio frequency power for a period of time, then load the silicon-containing gas and the hydrogen-containing gas into the reaction chamber. 4. The high density plasma trench filling method for reducing gas phase nucleation defects as claimed in claim 1, wherein the carrier gas comprises an inert gas. 5. The high-density plasma trench filling method for reducing gas-phase nucleation defects as claimed in claim 1, wherein in the second deposition step, further comprising loading the carrier gas and the oxygen-containing gas into the reaction chamber And after turning on the radio frequency power supply for a period of time, the silicon-containing gas is loaded first, and then the hydrogen-containing gas is loaded into the reaction chamber. 6. The high-density plasma trench filling method for reducing gas-phase nucleation defects as claimed in claim 5, wherein in the second deposition step, after loading the silicon-containing gas into the reaction chamber, until the The time interval before the hydrogen-containing gas is introduced into the reaction chamber is greater than or equal to 1 second. 7. The high-density plasma trench filling method for reducing gas phase nucleation defects as claimed in claim 5, wherein in the second deposition step, after loading the silicon-containing gas into the reaction chamber, until the The time interval before the hydrogen-containing gas enters the reaction chamber is 1 second to 4 seconds. 8 . The high density plasma trench filling method for reducing gas phase nucleation defects as claimed in claim 5 , wherein in the second deposition step, the hydrogen-containing gas is loaded into the reaction chamber in a manner of increasing flow rate. 9. The high density plasma trench filling method for reducing gas phase nucleation defects as claimed in claim 1, wherein the silicon-containing gas comprises silane gas. 10. The high-density plasma trench filling method for reducing gas-phase nucleation defects as claimed in claim 1, wherein the reactive gas used in the etching step comprises fluorine-containing compounds and the hydrogen-containing gas. 11. The high-density plasma trench filling method for reducing gas-phase nucleation defects as claimed in claim 10, wherein the fluorine-containing compound comprises one of nitrogen fluoride, halothane compound, and sulfur fluoride. 12. A high-density plasma trench filling method for reducing gas-phase nucleation defects, comprising: (a) providing a substrate having a groove therein; (b) performing a first deposition step to partially fill the trench with dielectric material; (c) performing an etching step to partially remove the dielectric material in the trench; and (d) performing a second deposition step, partially filling the trench with the dielectric material, wherein the reaction gas used in the second deposition step includes carrier gas, oxygen-containing gas, silicon-containing gas, and hydrogen-containing gas gas, and after loading the carrier gas, the oxygen-containing gas, and the silicon-containing gas into the reaction chamber and turning on the radio frequency power for a period of time, then load the hydrogen-containing gas into the reaction chamber. 13. The high density plasma trench filling method for reducing gas phase nucleation defects as claimed in claim 12, further comprising repeating step (c) and step (d) until the dielectric material fills the trench. 14. The high density plasma trench filling method for reducing gas phase nucleation defects as claimed in claim 12, wherein the reaction gas used in the first deposition step comprises the carrier gas, the oxygen-containing gas, the silicon-containing gas and The hydrogen-containing gas, and after loading the carrier gas, the oxygen-containing gas, and the silicon-containing gas into the reaction chamber and turning on the radio frequency power for a period of time, then load the hydrogen-containing gas into the reaction chamber. 15. The high density plasma trench filling method for reducing gas phase nucleation defects as claimed in claim 12, wherein the carrier gas comprises an inert gas. 16. The high density plasma trench filling method for reducing gas phase nucleation defects as claimed in claim 12, wherein the silicon-containing gas comprises silane gas. 17. The high-density plasma trench filling method for reducing gas-phase nucleation defects as claimed in claim 12, wherein the reactive gas used in the etching step comprises a fluorine-containing compound and the hydrogen-containing gas. 18. The high-density plasma trench filling method for reducing gas-phase nucleation defects as claimed in claim 17, wherein the fluorine-containing compound comprises one of nitrogen fluoride, halothane compound, and sulfur fluoride. 19. The high-density plasma trench filling method for reducing gas-phase nucleation defects as claimed in claim 12, wherein in the second deposition step, after loading the silicon-containing gas into the reaction chamber, until the The time interval before the hydrogen-containing gas is introduced into the reaction chamber is greater than or equal to 1 second. 20. The high-density plasma trench filling method for reducing gas-phase nucleation defects as claimed in claim 12, wherein in the second deposition step, after loading the silicon-containing gas into the reaction chamber, until the The time interval before the hydrogen-containing gas enters the reaction chamber is 1 second to 4 seconds. 21. The high-density plasma trench filling method for reducing gas-phase nucleation defects as claimed in claim 12, wherein in the second deposition step, the hydrogen-containing gas is loaded into the reaction chamber in an increasing flow rate. 22. A high-density plasma trench filling method for reducing gas-phase nucleation defects, comprising: (a) providing a substrate having a groove therein; (b) performing a first deposition step to partially fill the trench with dielectric material; (c) performing an etching step to partially remove the dielectric material in the trench; (d) performing a second deposition step, partially filling the trench with the dielectric material, wherein the reactive gas used in the second deposition step includes a carrier gas, an oxygen-containing gas, and a silicon-containing gas; and (e) performing a third deposition step, partially filling the trench with the dielectric material, wherein the reaction gas used in the third deposition step includes the carrier gas, the oxygen-containing gas, the silicon-containing gas with hydrogen-containing gas. 23. The high-density plasma trench filling method for reducing gas-phase nucleation defects as claimed in claim 22, further comprising repeating step (c), step (d) and step (e) until the dielectric material fills the trench . 24. The high-density plasma trench filling method for reducing gas-phase nucleation defects as claimed in claim 22, wherein the reaction gas used in the first deposition step comprises the carrier gas, the oxygen-containing gas, the silicon-containing gas, and the hydrogen-containing gas. 25. The high density plasma trench filling method for reducing gas phase nucleation defects as claimed in claim 22, wherein the carrier gas comprises an inert gas. 26. The high density plasma trench filling method for reducing gas phase nucleation defects as claimed in claim 22, wherein the silicon-containing gas comprises silane gas. 27. The high-density plasma trench filling method for reducing gas-phase nucleation defects as claimed in claim 22, wherein the reactive gas used in the etching step comprises a fluorine-containing compound and the hydrogen-containing gas. 28. The high-density plasma trench filling method for reducing gas-phase nucleation defects as claimed in claim 27, wherein the fluorine-containing compound comprises one of nitrogen fluoride, halothane compound, and sulfur fluoride.

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