WO1998039799A1

WO1998039799A1 - Post-treating method for plasma etching

Info

Publication number: WO1998039799A1
Application number: PCT/JP1997/000897
Authority: WO
Inventors: Kazue Takahashi; Ryoji Fukuyama; Tadamitsu Kanekiyo; Tsuyoshi Yoshida
Original assignee: Hitachi, Ltd.; Hitachi Techno Engineering Co., Ltd.
Priority date: 1997-03-05
Filing date: 1997-03-19
Publication date: 1998-09-11
Also published as: TW367555B

Abstract

A post-treating method for plasma etching is used for post-treating a semiconductor substrate including aluminum wiring after the substrate is etched with a plasma by using a gas containing chlorine. During the post-treatment, a gas containing hydrogen and fluorine is used as an ashing gas. The mixing ratio of the fluorine gas is less than 2 %, preferably, about 1 %. Therefore, the time for the post-treatment can be shortened and side wall removal can be improved because the ashing speed of the resist is increased and anticorrosion treatment and removability of the substrate are excellent. Therefore, the throughput of substrate treatment and the yield of the substrate are improved.

Description

Specification

Post-treatment method of plasma etching

Technical field

The present invention relates to a plasma etching processing method for performing fine processing on a substrate in a semiconductor device manufacturing process. The present invention particularly relates to a post-treatment method to be performed after etching a metal laminated wiring made of aluminum or an aluminum alloy, wherein the chlorine component in the gas used in the plasma etching is etched. The present invention relates to a post-treatment method of plasma etching for preventing corrosion of metal wiring caused by remaining on a surface. Background art

Conventional post-processing methods of plasma etching processing include a step of removing a resist used as a mask for etching (referred to as “ashing processing”) and an adhesion film (sidewall protection film) formed on the side wall of the metal wiring during the etching. ) And an etching process to further remove the sidewall protective film. The post-processing method of the present invention is a post-processing method in a narrow sense, and belongs to the former (assing process). Unless otherwise specified, the post-processing method is an asshing process.

The metal wiring of semiconductor devices made of aluminum alloys (such as Al—Cu—Si or Al—Si) includes a barrier layer such as Tin on the substrate side, and a similar TiN layer on the front side. Are formed in a laminated film structure in which a cap layer is formed. Metal wire This is etched with a mixed gas plasma usually contain additive gas to the mixed gas plasma or further of C 1 ₂ and BC 1 _3. Since A 1 is also etched by only C l ₂ gas, in order to E Tsuchingu a metal wiring in a vertical shape, the lateral etch suppressing protective film, rock It is necessary to form a loose sidewall protection film. The sidewall protective film is composed of an etching reaction product and a resist component, and is formed on the sidewall of the metal wiring while proceeding simultaneously with the etching. However, the sidewall protective film is unnecessary after the etching is completed, and it is necessary to remove the resist and remove the sidewall protective film. Usually, the resist removal operation is performed immediately after etching without exposing the semiconductor substrate to the atmosphere. After this assing process, the process starts to remove the sidewall protective film. Since this process is a wet process using water or a chemical solution, the semiconductor substrate is once taken out to the atmosphere and then performed. In some cases, the sidewall protection film is removed immediately after being taken out to the atmosphere, or in other cases, several hours to several days later. Meanwhile, the chlorine component having entered during the etching is in the sidewall protective film (C 1 _2, C 1) are included. Since this chlorine component is not completely removed in the asshing process, when the semiconductor substrate is subsequently taken out to the atmosphere, it reacts with moisture in the atmosphere to form hydrochloric acid and corrode metal wiring. Therefore, in the polishing treatment, the resist must be removed and the residual chlorine component in the sidewall protective film must be removed. Another idea is that even if the residual chlorine component is present in the sidewall protective film, it does not have to react with moisture in the atmosphere until the sidewall protective film is removed. Another method is to cover the surface with a corrosion-resistant protective film (passivation treatment). In this case, in order to isolate the residual chlorine component of moisture and the side wall protective film in the atmosphere to form a film, such as A 1 ₂ 0 ₃ on the surface of the sidewall protective film.

One example of the latter method is described in Japanese Patent Publication No. 58-123432. Here, after the aluminum wiring is etched with plasma containing C1, sulfur hexafluoride SF ₆ plasma treatment is performed to passivate the surface of the aluminum wiring with F. Although this is not described in detail in the above-mentioned patent publication, by exposing the surface of the side wall protective film of the aluminum wiring to fluorine plasma, aluminum fluoride A 1 F ₃ is formed as a corrosion-resistant protective film. It is thought that it was. A 1 F ₃ is a water-soluble but stable compound, and is considered to have been able to prevent the reaction between atmospheric moisture and residual chlorine components.

Among the post-treatment methods for corrosion resistance performed after etching the aluminum wiring, the following method is known for the former method, that is, the treatment method for removing the residual chlorine component in the sidewall protective film. ing.

Although the mechanism of corrosion prevention is not described, in the example described in Japanese Patent Publication No. 62-30268, the post-etching post-treatment of mixing oxygen and fluorocarbon (Examples 0 ₂ and CF ₄ ) Gas is used. Further, in Japanese Laid-7- 2 2 1 0 7 5 JP, it describes a post-treatment 0 ₂ mixed gas plasma of H ₂ 0. In the example described in Japanese Patent Application Laid-Open No. 1-169929, a mixed gas plasma of O ₂ and H ₂ 0 is used, and the mixing ratio of the two is defined, and the generation efficiency of oxygen atoms 0 effective for resist asssing is defined. It suggests ways to increase the quality. Further, in the embodiment described in Japanese Patent Publication No. Hei 2-7-172525, various mixed gas and H 2 OH, 〇, etc. are produced in order to improve the resist ashing speed. The mixing ratio is specified. Examples include 0 ₂ , 02 + H ₂ 0, 0 ₂ + N ₂ , 0 ₂ + H 20 + N ₂ s 02 + H ₂ 0 + CF ₄ , 〇 ₂ + H ₂ , 〇 _2, which is a + H ₂ + N physician. Here, the oxide film S I_〇 _second base gas system (CF ₄₎ in the aluminum wiring including the F is likely to be etched, it can be prevented by the mixing ratio of H ₂ 〇 more than 1 0% It is described. The above-mentioned polishing treatment is mainly described as a method for improving the resist removal rate (assisting rate), but does not describe the removability of the residual chlorine component in the sidewall protective film.

Further, in the embodiment described in Japanese Patent Application Publication No. 2-49425, a method of removing the resist and removing the side wall protective film using a mixed gas of halogen gas and a gas containing at least hydrogen is disclosed. It is shown. Examples of halogen _{_{gas, SF 6, NF 3, CF}} 4, BF 3, PF 3, PF have X e F _2, F ₂ are mentioned. This example aims at removing the resist by a damage-free dry process and removing the sidewall protective film. The document states that the sidewall protective film can be removed by hydrofluoric acid treatment, but the underlying oxide film is also etched at the same time, so it is necessary to remove the sidewall protective film by a dry process.

Example described in U.S. Patent US 5, 3 8 2, 3 1 6 , in order to simultaneously remove the registry and the side wall protective film by plasma treatment after Edzuchingu consists gas and 〇 ₂ or H ₂ 〇 containing F gases Is used. In this case, the fluorine mixture ratio is set to 0.1 to 10%, but the material to be etched is polysilicon or polysilicon, and is used for etching of aluminum wiring and the like which is the target of the present invention. It's not something that I did. The sidewall protective film formed in the etching of A 1 is not removed even when a plasma treatment is performed by introducing a fluorine-based gas.

In the example described in Japanese Patent Application Laid-Open No. 7-326609, after etching the wiring of the A1 or A1 alloy film, for the purpose of preventing corrosion and facilitating removal of the side wall protective film, gas containing _{_{F (CF 4, NF 3,}} SF 6) or the water-soluble and fluoride sidewall protective film to remove the C 1 Ri by to plasma treatment in a mixed gas of H _2, in the next step Examples are shown of washing with water and removing the etching mask (resist). The main purpose of this embodiment is to easily remove the side wall protective film by washing with water, and CF ₄ is the main gas. For this reason, it is assumed that washing is performed after the plasma treatment, and it is not described whether C1 is removed to such an extent that corrosion does not occur when the substrate is left in the air after the plasma treatment. In addition, the removal of the resist is to be performed in the last step, and the post-etching post-treatment includes three steps: a plasma treatment, a water washing, and an assing treatment. At this point, if atshing is performed simultaneously in the plasma processing, If the sidewall protective film can be easily removed by washing after the plasma treatment, the number of processes becomes two, and the throughput can be improved and the substrate processing cost can be reduced.

The above-mentioned prior art mainly aims at removing the resist efficiently and in a short time. Methods and mechanisms for actively removing residual chlorine components from aluminum wiring have not been clarified, and remain issues to be solved. In addition, there is no disclosure of a plasma treatment that takes into account the process of removing the sidewall protective film after the ashes, and Japanese Patent Application Laid-Open No. 2-49425 states that the sidewall protective film is removed by fluorine radicals. Japanese Patent Application Laid-Open No. 7-326609 only mentions an example in which the side wall protective film is fluorinated by plasma and removed by washing with water.

The side wall protective film of the aluminum wiring is composed of A1, C, Cl, Si, 0, etc., and A1 is not removed by fluorine radicals. Rather, A 1 F ₃ is formed, and A 1 ₂ 0 ₃ yo Ri stable film. Therefore, it is difficult to remove the sidewall protective film with a mixed gas system of fluorine and hydrogen in aluminum wiring. Immediately after the side wall protective film is fluorinated with fluorine plasma, the side wall protective film is removed by rinsing with water. However, the need for a resist removal step is required. It is difficult to remove residual chlorine components to a level that does not cause corrosion even if left for a long time. Also, if F remains and reacts with atmospheric moisture to produce hydrogen fluoride HF, corrosion by HF may occur.

In the post-processing after etching the aluminum wiring, it is necessary to remove the resist and the residual chlorine component in the sidewall protective film. This is to remove the sidewall protective film after the substrate is taken out into the atmosphere after the ashing process. This is to prevent corrosion on the substrate surface, particularly the aluminum wiring portion before proceeding to the etching process. In other words, the side wall is removed simultaneously with the removal of the resist. It must be a process in which the reaction to remove the residual chlorine component in the protective film proceeds. Furthermore, in the present invention, it is also a major problem that a step after removing the resist and the residual chlorine component, that is, a process in which the sidewall protective film is easily removed in the sidewall protective film removing step is performed in the asshing step. And In particular, when etching a substrate made of aluminum laminated wiring, corrosion occurs even with a trace amount of residual chlorine components, so processing that can completely remove residual chlorine components is required. Disclosure of the invention

In the present invention, for solving the above problems, the H ₂ 0 removal rate of registry can be ensured to some extent was the main gas. Then, removal of the residual chlorine components in the sidewall protective film, H generated when generating the H ₂ 0 plasma, 0:. To form a ¾ 11 (1, is removed by vaporization Further, after Atsushingu one of the reasons for removal of the sidewall protective film becomes difficult, since the sidewall protection film composed mainly of a 1 is a 1 ₂ 0 ₃ is oxidized into Atsushingu, dissolved in the chemical liquid Al force Li Ya acid The side wall protective film is treated with F to make it A 1 F _3, and is easily dissolved in H ₂₀ to make the side wall protective film easy to peel off. The problem with using F is that if the mixing ratio of F is too high, the aluminum wiring will corrode.However, by reducing the mixing ratio of F to a level that does not cause corrosion, the removal of resist and the residual chlorine component Removal and improvement of the peelability of the sidewall protective film can be satisfied at the same time. Description

FIG. 1 is a diagram showing an example of a plasma etching apparatus for carrying out the present invention.

FIG. 2 is a diagram showing the structure of the aluminum laminated film.

FIG. 3 is a diagram showing an aluminum wiring shape after etching. FIG. 4 is a schematic diagram of the sidewall protective film.

FIG. 5 is a diagram showing measurement results of residual chlorine and residual fluorine. BEST MODE FOR CARRYING OUT THE INVENTION

The phenomenon that aluminum wiring corrodes when left in air after plasma etching of aluminum wiring depends on the material structure of aluminum wiring. In particular a laminated film (the substrate side and the like titanium nitride, the substrate S i / oxide film S i 0 ₂ /窒化Chiyun T i N / Aruminiumu Alloy A 1 - S i - C u / nitrogen Kachiyun T i N / register PR). This is due to the fact that corrosion is likely to occur electrochemically. That is, a battery effect works between the stacked films made of different metals. Single-layer film of an aluminum wiring (substrate S i / oxide film S i 0 ₂ / Aluminum Alloy A l- S i- Cu / registration be sampled PR) is hard to corrode no battery effect. Hereinafter, the above substrate is referred to as an aluminum laminated substrate or an aluminum single layer substrate.

FIG. 1 shows a plasma etching apparatus embodying the present invention. The aluminum laminated semiconductor substrate 10 is taken out of the cassette 2 on the cassette table 1 by the robot arm 3 installed on the atmosphere side and introduced into the load lock chamber 5. Next, the door 4 of the load lock chamber 5 is closed, and evacuation is started. The vacuum evacuation is carried out slowly so as not to wind up the foreign matter in the load lock chamber 5. The valve 6 between the load lock chamber 5 and the transfer chamber 9 is opened when the air is exhausted to a predetermined pressure or less. The transfer chamber 9 is constantly evacuated and maintained at a high vacuum. The semiconductor substrate 10 is transferred from the load lock chamber 5 to the transfer chamber 9 by the robot arm 11 provided in the transfer chamber 9. Immediately after the transfer, the valve 6 is closed. Then, the pressure in the etching chamber 1 3 is evacuated to sufficiently high vacuum, preferably sure that the 1 0- ⁵ T orr table below, between the etching chamber 1 3 and the transfer chamber 9 The valve 14 is opened, and the semiconductor substrate 10 is carried into the etching chamber 13. In etching chamber 1 3 The semiconductor substrate 10 is mounted on a substrate mounting electrode (not shown). The electrodes are capable of electrostatically adsorbing the semiconductor substrate 10, and a heat gas of about several Torr to 10 Torr is introduced into the back surface of the semiconductor substrate 10 to increase the heat transfer efficiency between the electrode and the substrate. After the valve 14 is closed, the gas inlet C l ₂ (not shown) as a gas for etching and BC 1 _3, the additive gas is introduced in addition to their in some cases. Since the electrode of this embodiment is of a monopole type that applies a high voltage to the electrostatic attraction film via the plasma, the plasma is ignited by microwaves after the introduction of the etching gas. With the plasma ignited, a high voltage for electrostatic attraction is applied to the electrodes, and the semiconductor substrate is attracted to the electrodes. This semiconductor substrate is previously controlled at a temperature of about 20 to 50 ° C. In this state, lithium gas is introduced into the back surface of the semiconductor substrate. When the pressure of the vapor gas reaches several Torr, the substrate temperature can be controlled by the electrode surface temperature. In this state, a high-frequency voltage of several 100 kHz to several 10 MHz, preferably 800 kHz to 2 MHz is applied to the electrode, and a bias voltage is applied to the substrate. The etching gas ions, which have been turned into a plasma state by the microwave, are drawn vertically into the semiconductor substrate simultaneously with the application of the high frequency voltage. Radicals such as electrically neutral C1 in the etching gas enter the semiconductor substrate from random directions, and the etched portion 102a (the resist is removed) of the aluminum laminated film shown in FIG. Part). In the case of A1, chlorine radicals are etched, but the aluminum laminated film shown in FIG. 2 is not etched only by adsorbed chlorine radicals because the TiN is formed in the cap layer 102. However, with the help of high-energy ions drawn into the substrate by applying a high-frequency voltage, the TiN layer 102 is etched by so-called ion assist etching. When the etching of the TiN layer 102 is completed, the surface of the substrate becomes an Al alloy 103. A 1 is etched chloride A 1 C 1 ₃ and (or A l ₂ C 1 _6), and the removed vaporized. Some of the vaporized aluminum chloride is It collides with the side wall of the aluminum wiring (hereinafter simply referred to as the side wall) and is adsorbed on the side wall. Also, part of the aluminum chloride released into the plasma, as it is or after being decomposed by the plasma, re-enters the semiconductor substrate and adheres to the side wall. Further, a part of the resist 101 is also etched. A part of it collides directly with the side wall and is adsorbed. Also, once released into the plasma, it re-enters and adheres to the side walls. In this manner, a film composed of A 1, Cl, and C and a side wall protective film are formed on the side walls. This film continues to grow as etching proceeds, but is also etched at the same time, so it is actually very thin, a few nm. Since the sidewall protective film is formed, even if chlorine radicals are adsorbed on the sidewalls of the aluminum wiring, the aluminum wiring is not etched, and as a result, anisotropic etching of a vertical shape is performed. After the aluminum wiring is etched under the aluminum interconnection layer is a barrier layer 1 0 4 der Ru in i N, it is S i 0 ₂ and the Edzuchingu material as the underlying layer 1 0 5 varies. Since the chloride of Ti has a high vapor pressure, the probability of being incorporated into the sidewall protective film is small. However, in the overetching after the etching depth reaches the oxide film, Si is slightly etched, and Si also adheres to the outermost surface of the sidewall protective film. Thus, the etching of the aluminum laminated film is completed. At the end of the etching, the high-frequency voltage applied to the electrode is stopped while maintaining the microwave discharge. Next, the supply of the Helium gas on the backside of the substrate is stopped to lower the backside pressure sufficiently. In this state, the output of the microphone mouth wave is stopped, and the gas supply is also stopped. The etching chamber 13 is evacuated for a while, and when a high vacuum is obtained, the valve 14 with the transfer chamber 9 is opened, and the semiconductor substrate 10 is carried out of the etching chamber 13 by the robot arm 11. The resist film thickness at this time is about 1 μm. Next, it is confirmed that the pressure in the assing chamber 18 is equal to or lower than a predetermined pressure, and the valve 19 between the assing chamber 18 and the transfer chamber 9 is opened to transfer the semiconductor substrate 10 to the asshing chamber 18. And place it on a substrate holder (not shown). Substrate holder is 150 to 300 ° C, preferably at 200 to 250 ° C. Although the temperature of the semiconductor substrate has reached several 10 ° C. due to heating in the etching chamber 13, the temperature hardly rises when the semiconductor substrate is placed on the substrate holder. As the gas for asshing is introduced and the pressure rises, the heat conduction between the substrate holder and the semiconductor substrate improves, and the temperature of the semiconductor substrate gradually approaches a constant temperature. The assing gas is a mixed gas of H ₂ 〇 and CF ₄ . Both flow, the total flow rate set to 5 0 0 cm ³ / min- constant, H ₂ 0 / CF _4: was 49 5 5, 4 7 5/ 2 5 cm 3 / min. The pressure was 2 Pa and the temperature of the substrate holder was 250 ° C. The plasma was generated by introducing microwave 100W. The plasma ignition dissociates the assing gas and generates radicals such as H, OH, 〇, F, CF, CF ₂ , and CF ₃ . Oxygen radical 0 is combined with carbon C in the resist to become C 0 and is vaporized and exhausted. In this manner, the asshing is completed in about 50 to 60 seconds. In this embodiment, over-asing is further performed for 120 seconds. After that, supply of the assing gas is stopped and high vacuum evacuation is performed. When the pressure drops to a predetermined value, the valve 19 is opened, the substrate 10 is taken out to the transfer chamber 9, and further sent to the load lock chamber 24 (unloading chamber). In the load lock chamber 24, after the valve 23 is closed, a slow leak is performed using nitrogen gas 26, and when the pressure reaches a pressure slightly higher than the atmospheric pressure, the door 25 to the atmosphere is opened, and the robot is moved to the cassette 2. Unload by arm 3. After this, the process may immediately proceed to the step of removing the side wall protective film, but in some cases, the process may wait for a while in the air or in a nitrogen gas atmosphere until the next process. At this time, the aluminum wiring must not corrode. In this example, when the mixing ratio of CF ₄ was about 1%, the best characteristics were exhibited, and no corrosion was observed even after 100 hours. In addition, when treated with an assing gas containing CF ₄ , the removal characteristics of the side wall protective film were good irrespective of the mixing ratio of CF _{4, and} no residual side wall protective film was generated.

Hereinafter, the reason why the result of the present invention was obtained will be described. Although the removal rate of the registry are described among the prior art, a case of adding other CF ₄ or H ₂ 〇 in pairs ◦ _2, the registry removal rate at 5-1 about 0% up to Become. Even when CF ₄ is added to H ₂₀ , the resist removal rate is maximized at a mixing ratio of about 5 to 10%. In addition, in order to obtain a large resist removal rate, a gas containing O ₂ is used in the conventional technology. However, A1 adheres to the resist surface after etching of the aluminum wiring because the reaction product at the time of etching re-enters the resist. This A 1 is not removed by an assing gas containing O ₂ . Rather, if the area occupied by the A1 attachment area is large, resist removal is hindered. The inventors have found that when an assing gas containing O ₂ is used, the resist portion excluding the A 1 attached portion is removed by the oxygen radical 0, so that the area ratio occupied by the A 1 attached portion gradually increases. As a result, it has been found that the resist removal speed is reduced. There is also a case where the registry With Atsushingugasu comprising 〇 ₂ may remain without being removed. However, 0 ₂ with H ₂ 0 without further the use of gas CF ₄ containing F, A 1 attached to the registry surface is fluoride, occupied even if progress Atsushingu of A 1 attachment portion It was found that the area ratio did not change, and as a result, the resist removal rate did not change, and it was possible to remove the resist until the end. Although the H ₂ 0 is included an oxygen atom, a plasma high proportion present as 0 H than 0, the ratio of oxidizing the A 1 of registry surface small compared to the case of the 0 ₂ gas . Also, A 1 reacts more easily with F than with 0. This also suppresses the oxidation of A1 on the resist surface. As described above, aluminum wiring is efficiently performed with a mixed gas of H ₂₀ and CF ₄ .

In the present invention, the mixing ratio of CF ₄ is set to 2% or less, preferably 1%. The reason for this is that, as described above, in the mixed gas system of the present invention, when the mixing ratio of CF 4 is about 5 to 10%, the resist removal rate is the highest, but the removal of residual chlorine components in the side walls is not possible. Will be enough. The reason is that Although the protective film 106 is schematically shown, the residual chlorine component in the sidewall protective film 106 reacts with H or 0 H to be removed as HC 1, so that the protective film 106 is removed. Sufficient H, 0 H must be supplied. However, when the supply of F is large, the surface of the sidewall protective film 106 is covered with the strong film 107 of A 1 F ₃ as shown in FIG. Therefore, the asshing ends with C 1 remaining in the sidewall protective film 106. Thereafter, Ri crack A 1 F ₃ film stress due to a difference in thermal expansion between A 1 F ₃ film 1 0 7 and the aluminum wire 1 0 3 occurs by the reaction H ₂ 0 and A l F ₃ in the atmosphere If the A 1 F ₃ film 107 is damaged, (1) in the side wall protective film 106 reacts with 1 ^ ₂₀ in the atmosphere. As a result, the aluminum wiring 103 corrodes. for even greater amount of residual Tomefu Tsu element in the side wall protective film 1 0 6, hydrofluoric acid HF are formed by reaction with H ₂ 0 in the air, the aluminum wiring 1 0 3 is corroded. However, the CF ₄ When the mixing ratio is sufficiently reduced, the A 1 F ₃ film 107 is formed on the surface of the side wall protective film 106, but is not strong enough to completely block H and 〇H from entering. As a result, C 1 does not remain inside the side wall protective film 106 and there is little residual fluorine, so that the aluminum wiring 103 does not corrode.

By the way, corrosion depends on the amount of chlorine and fluorine remaining after polishing. Therefore, the same treatment as the above corrosion test conditions was performed using an aluminum film substrate, and the amounts of chlorine and fluorine remaining in the aluminum film were evaluated by a thermal desorption method. The thermal desorption method is a method of measuring the composition of a gas that desorbs by elevating the temperature of a sample in a vacuum and the amount of released gas, and enables analysis of the gas remaining in the aluminum film. Figure 5 summarizes the results of the above corrosion tests by the amount of residual chlorine and residual fluorine. The horizontal axis indicates the mixing ratio of CF ₄ , and the vertical axis indicates the amounts of residual chlorine and residual fluorine after asshing. The right end of FIG. 5 also shows the measurement results of the residual chlorine amount and the residual fluorine amount after etching. A large amount of chlorine remains in the aluminum film before assing. In contrast, fluorine is used during etching. Since it is not used, the amount of residual fluorine is small and can be regarded as the measurement limit value. As the mixing ratio of CF ₄ is increased, the amount of residual chlorine and fluorine in the aluminum film is increasing. From the results in Fig. 5, it is necessary to determine the level at which the corrosion does not occur. In the corrosion test results of the above given that mixing ratios of CF ₄ is not corrosion occur in about 1%, and the mixing ratio of 1% residual chlorine content and residual fluorine Yoryou of CF ₄ and tolerance. The solid line also shown in Fig. 5 is the value. From Figure 5, to the mixing ratio of 2% CF ₄ is less than the allowable value. When the mixing ratio of CF ₄ is 3%, the value is partially below the allowable value, but may exceed the allowable value, and there is a possibility of corrosion. These results Atsushin grayed were found to meet the corrosion characteristics of a mixed gas system of H ₂ 0 / CF ₄ to less mixing ratio of 2% CF _4.

Furthermore, since not using 〇 ₂ Asshingugasu, the A 1 F ₃ which A 1 ₂ 0 ₃ which inhibits the removability upon sidewall removal is not formed on the side wall protective film, but rather is dissolved in H ₂ 0 formed Have been. Therefore, the removability of the sidewall protective film is excellent.

As described above, according to the present invention, C 1 in the sidewall protective film is removed to prevent corrosion while satisfying the resist removal rate, and post-processing which is excellent in the removal characteristic of the sidewall protective film is also achieved. Became possible.

In the present invention, a mixed gas system of H ₂₀ and CF ₄ has been described.However, the same effects can be obtained with a gas system such as NF ₃ or SF ₆ containing F for the above-described reason. Needless to say. In addition, although the assuring process was performed without changing the conditions in the middle, considering that the bond between A1 and F is stronger than A1 and 0, the resist was removed after the process of the present invention was performed. Ashing may be performed with a gas system containing O ₂ to improve the removal rate.In this case, A 1 F ₃ is formed to some extent on the surface in the sidewall protective film, and the sidewall removal characteristics are not hindered. . Also, depending on the aluminum laminate film, the gas system containing 0 _2, the registry in the mixed gas, for example 〇 ₂ and H ₂ 0 is removed There may be, in this case, at 0 ₂ and H ₂ 〇 mixed gas in the first step, it is effective to process in subsequent gas system of the present invention. Also in this case, the surface of the sidewall protective film is fluorinated in the latter half of the process, and the removal characteristics of the sidewall protective film are improved.

According to the present invention, a sufficient resist removing speed can be obtained even in an aluminum laminated film in which the resist removing speed is reduced due to the effect of aluminum attached to the resist surface. In addition, the residual chlorine component during the etching is completely removed, and the aluminum wiring can be prevented from being corroded when left in the air after the completion. Furthermore, the removal of the side wall protective film is also easy because the water-soluble A 1 F ₃ is formed. For this reason, it is possible to expect an effect without the need to use special chemicals.

Claims

The scope of the claims

1. After a metal thin film containing aluminum provided on a semiconductor substrate is plasma-etched with a gas containing chlorine, the chlorine component remaining on the surface of the workpiece is exposed to the air. In a post-treatment method for plasma etching that removes without etching, a mixed gas of a gas containing hydrogen and a gas containing fluorine is introduced into a plasma, and the surface to be etched is treated with the mixed gas plasma. Post-treatment method for plasma etching.

2. The post-treatment method for plasma etching according to claim 1, wherein a mixing ratio of a gas containing fluorine of the mixed gas is 2% or less.

3. The post-treatment method for plasma etching according to claim 1, wherein the gas containing hydrogen is selected from the group consisting of hydrogen gas, water, and alcohol, and the gas containing fluorine is fluorine gas. F _2, the post-processing method for plasma etching, characterized in that it is selected from the group of fluorocarbon gas C _x H _y F _z, 6 sulfur hexafluoride SF _6, 3 nitrogen fluoride NF _3.

4. In the post-processing method for plasma etching according to claim 1, after the processing of the surface to be etched is performed, a gas plasma containing oxygen or a gas containing oxygen and hydrogen are continuously contained. A post-processing method for plasma etching, which comprises performing a process using a mixed gas plasma of gases.

5. In the post-treatment method for plasma etching according to claim 1, before performing the treatment on the surface to be etched, a gas pump containing oxygen is required. A post-treatment method for plasma etching, which comprises performing a treatment using plasma of a mixed gas of a gas containing plasma and a gas containing oxygen and a gas containing hydrogen.

6. The post-processing method for plasma etching according to claim 1, wherein the plasma etching process and the post-processing are performed in another vacuum-separated processing chamber. Post-processing method.

7. The post-treatment method for plasma etching according to claim 1, wherein the material to be processed includes at least a layer made of aluminum or an aluminum alloy, and at least a layer made of the aluminum or aluminum alloy. A post-treatment method for plasma etching, comprising a laminated film having a layer made of another metal formed on one surface.

8. The post-treatment method for plasma etching according to claim 1, wherein the post-treatment is a radical-based plasma treatment in which the incidence of ions on the material to be treated is restricted. Post-processing method for etching.