CN205609515U - Reliability testing structure - Google Patents

Abstract

The utility model provides a reliability testing structure, comprising: a substrate provided with an active area and an isolation structure, a barrier layer to be covered on the isolation structure, conductive plugs formed at both ends of the active area, and a conductive The conductive layer connected by the plug point, wherein the active region, the conductive plug and the conductive layer form a serial structure. When the resistance test is carried out on the series connection structure of the reliability test structure in the utility model, the connection status between the active area and the conductive plug can be judged according to the detected resistance value, thereby confirming that the active area is connected to the conductive plug. Is there any barrier layer remaining. At the same time, the reliability test structure provided by the utility model can also be used to monitor the abnormality of the formation process of the barrier layer.

Description

Reliability Test Structure

technical field

The utility model relates to the technical field of semiconductor manufacturing, in particular to a reliability testing structure.

Background technique

In the manufacturing process of integrated circuits, metal silicide needs to be formed in some areas of the device, such as the position where the active region is connected to the conductive plug. Metal silicide needs to be formed to reduce contact resistance and improve conductivity. However, metal silicide cannot be formed in some areas of the device, such as areas such as high-resistance polysilicon and isolation structures. Therefore, before making the metal silicide, a barrier layer should be formed in the area where the metal silicide does not need to be formed, and the barrier layer will not react with the metal to prevent the formation of the metal silicide in the area where the metal silicide is not required to be formed. In the process of forming the barrier layer, a thicker photoresist is required, which leads to the occurrence of barrier layer residue at the bottom of the line due to photoresist residue when the line spacing is small The problem. If the barrier layer remains on the active region, the subsequently formed conductive plug will not be able to contact the active region, thereby affecting the performance of the device.

It has been found in practice that under strict control of photolithography process conditions, photoresist residue at the bottom of the lines can be basically prevented. And when the process conditions of lithography deviate slightly, or even fluctuate within the normal range of equipment parameters or process parameters, lithography residues may appear between the bottoms of the lines. As the size of devices continues to shrink, the problems of photoresist residue and film residue are becoming more and more serious in the process of using thicker photoresist. According to the traditional defect detection method, it is increasingly unable to meet the demand. For example, wafer inspection equipment is used to inspect wafers. Due to the limitation of the inspection accuracy of the wafer inspection equipment, the inspection equipment may miss inspection or fail to detect small defects.

Utility model content

The purpose of the present invention is to provide a reliability testing structure, through which the reliability testing structure can effectively detect whether there is a barrier layer left on the active area, and can monitor the abnormality of the formation process of the barrier layer.

The reliability test structure provided in the utility model includes: a substrate, a barrier layer, at least two conductive plugs and a conductive layer, at least one active region is formed in the substrate and each of the active regions A surrounding isolation structure, the barrier layer is formed on the isolation structure, at least one conductive plug is formed at both ends of each active region, and the conductive layer is formed on the conductive plug Above, the conductive plugs located at both ends of the same active region are respectively connected to two different conductive layers, so that the active region, the conductive plugs and the conductive layer form a serial structure.

Optionally, in the reliability test structure, an active region is formed in the substrate, and a conductive plug is formed at both ends of the active region.

Optionally, in the reliability test structure, a plurality of active regions are formed in the substrate, and a conductive plug is formed at both ends of each active region, and two adjacent Among the four conductive plugs on the active area, two conductive plugs located on different active areas are connected to the same conductive layer.

Optionally, in the reliability test structure, a plurality of the active regions are arranged in a meandering manner to form a serpentine structure.

Optionally, in the reliability testing structure, the serpentine structure has multiple different detour pitches.

Optionally, in the reliability test structure, the detour distance is multiplied according to the minimum design size.

Optionally, in the reliability test structure, a plurality of the active regions are arranged in an L-shape, U-shape, M-shape or W-shape.

Optionally, in the reliability test structure, the shape of the active region is a stripe.

Optionally, in the reliability test structure, the width of the active region is greater than or equal to the minimum design dimension.

Optionally, in the reliability test structure, the distance between the conductive plug and the isolation structure is greater than or equal to a minimum design dimension.

Compared with the prior art, in the reliability test structure provided by the utility model, the active region, the conductive plug and the conductive layer form a chain structure connected in series, and when the resistance test is performed on the reliability test structure, the A voltage or current is applied to the first and last ends of the chain structure, and then the resistance value of the chain structure can be obtained according to the detected corresponding current value or voltage value, and it can be judged according to the detected resistance value The connection status between the active area and the conductive plug can be obtained, so that it can be further inferred whether there is a barrier layer left on the active area. Therefore, by using the reliability test structure provided by the utility model, the abnormality monitoring of the formation process of the barrier layer can be carried out.

Description of drawings

Fig. 1A is a top view of the reliability testing structure of Embodiment 1 of the present utility model;

Fig. 1B is a cross-sectional view of the reliability testing structure of Embodiment 1 of the present utility model;

Fig. 2A is a top view of the reliability testing structure of the second embodiment of the utility model;

Fig. 2B is a sectional view of the reliability testing structure of the utility model embodiment 2 along the direction AA';

3A to 3C are schematic cross-sectional structural diagrams during the process of forming the reliability testing structure of Embodiment 1 of the present invention.

detailed description

As mentioned in the background art, during the photolithography process, the performance of the formed device is often affected by the residual photoresist. At the same time, as the size of the device continues to shrink, the traditional defect detection method is increasingly unable to meet the demand. . For this reason, the utility model provides a reliability testing structure to solve the problem of insensitive defect detection rate, and further, it can also be used for abnormal monitoring in the photolithography process.

A reliability testing structure provided by the utility model is used to detect photoresist residues in the formation process of the barrier layer, including: a substrate, a barrier layer, at least two conductive plugs and a conductive layer. At least one active region and an isolation structure located around each active region are formed, the barrier layer is formed on the isolation structure, and at least one of the active regions is formed on both ends of each active region. Conductive plugs, the conductive layer is formed above the conductive plugs, and the conductive plugs located at both ends of the same active region are respectively connected to two different conductive layers, so that the active region, the conductive plugs And the conductive layer forms a series structure.

In the reliability test structure provided by the utility model, the active region, the conductive plug and the conductive layer are connected in series, and when the resistance test is performed on the reliability test structure, the Apply a voltage or current to the end, and then according to the detected corresponding current value or voltage value, the resistance value of the series structure can be obtained, and then the connection between the active region and the conductive plug can be judged according to the obtained resistance value Therefore, it can be judged whether there is a barrier layer left on the active region, and then it can be deduced whether there is a problem of photoresist residue during the photolithography process. That is, by using the reliability test structure provided by the present invention, the abnormality monitoring of the formation process of the barrier layer can be carried out.

When using the reliability test structure provided by the utility model to detect, a standard resistance can be set according to the size and specific process of the actual reliability test structure, and then the detected resistance value is compared with the standard resistance, if the detected If the resistance value is less than the specified resistance, the contact between the conductive plug and the active area in the series structure is normal, and there is no barrier layer left on the active area; if the detected resistance value is greater than the specified resistance , then there is a problem of abnormal connection between at least one conductive plug and the active region in the series structure, which leads to an increase in resistance.

The reliability test structure proposed by the utility model will be described in further detail below in conjunction with the accompanying drawings and specific embodiments. According to the following description and claims, the advantages and features of the utility model will be more clear. It should be noted that all the drawings are in very simplified form and use inaccurate scales, which are only used to facilitate and clearly illustrate the purpose of the embodiment of the present utility model.

Embodiment one

FIG. 1A is a top view of the reliability testing structure of the first embodiment of the utility model, and FIG. 1B is a cross-sectional view of the reliability testing structure of the first embodiment of the utility model shown in FIG. 1A . As shown in Figure 1A and Figure 1B, the reliability test structure provided by this embodiment includes: a substrate, a barrier layer 120, at least two conductive plugs 130 and a conductive layer 140, an active region is formed in the substrate 111 and an isolation structure 112 located around the active region 111, the barrier layer 120 is formed on the isolation structure 112, and one conductive plug 130 is formed at both ends of the active region 111, so The conductive layer 140 is formed above the conductive plugs 130, and the two conductive plugs 130 in the active region 111 are respectively connected to two different conductive layers 140, so that the active region 111, the conductive plugs The plug 130 and the conductive layer 140 form a series structure.

In this embodiment, the active region 111, the two conductive plugs 130 located at both ends of the active region 111, and the two conductive layers 140 respectively connected to the two conductive plugs 130 jointly form a series structure. A voltage or current is applied to the two conductive layers 140 for testing. Then, the connection status between the active region 111 and the conductive plug 130 can be judged according to the test results, and then the remaining photoresist during the formation process of the barrier layer 120 can be deduced.

In this embodiment, an active region 111 is formed in the substrate, wherein the shape of the active region 111 is a strip, and its cross section may be a rectangle. The isolation structure 112 surrounds the active region 111 and has a rectangular ring shape in cross section. The width D of the active region 111 is greater than or equal to the minimum design dimension, and the minimum distance S between the conductive plug 130 and the isolation structure 112 is greater than or equal to the minimum design dimension. Since the smaller the width D of the active region 111 and the smaller the distance S between the conductive plug 130 and the isolation structure 112, the higher the process requirements for the subsequent formation of the barrier layer 120 are, therefore, if the reliability test The design dimensions of the structures all adopt the minimum design dimensions, which can improve the sensitivity of monitoring the abnormality of the formation of the barrier layer within the range required by the process capability. Therefore, when forming the barrier layer, even if there is a slight deviation in the process, it can be reflected in the reliability test structure, and the abnormality can be detected through the resistance test, so that the problem can be found in time and the expansion of the abnormality can be avoided.

Wherein, the material of the barrier layer 120 is, for example, silicon dioxide or silicon nitride, the material of the plug 130 is, for example, tungsten (W), and the material of the conductive layer 140 is, for example, copper (Cu) or aluminum (Al). .

The method for forming the reliability test structure provided by this embodiment will be further described in detail below with reference to FIG. 3A to FIG. 3C . 3A to 3C are schematic diagrams of the steps of forming the reliability test structure of Embodiment 1 of the present invention, wherein, FIG. 3A to FIG. 3C are schematic cross-sectional views along the direction perpendicular to the length of the active region in FIG. 1A .

First, as shown in FIG. 3A , a substrate is provided, in which an active region 111 and an isolation structure 112 are formed, and the surface of the isolation structure 112 is a region where a barrier layer needs to be formed.

Next, as shown in FIG. 3B , a blocking layer 120 is deposited on the substrate, and a photoresist 300 is spin-coated on the blocking layer 120 . Wherein, the barrier layer 120 is, for example, a metal silicide barrier layer. During semiconductor manufacturing, the formation of metal silicides is achieved through the property of metals to react with silicon. Usually, a metal silicide blocking layer is covered in the area where the metal silicide is not required to be formed, so as to prevent the metal silicide from forming in the area where the metal silicide is not to be formed. During the photolithography process for forming the metal silicide barrier layer, the thickness of the photoresist required to be used is relatively thick, for example greater than

Then, photolithography and etching processes are performed. Since the thickness of the photoresist 300 is relatively thick, and the width of the active region 111 is relatively small. Therefore, when performing the photolithography process, it is necessary to strictly control the conditions of the photolithography process, otherwise, when a slight deviation occurs in the photolithography process, it may cause the problem that the photoresist 300 on the active region 111 cannot be completely removed, such as As shown in FIG. 3C , due to the remaining photoresist, the barrier layer 120 on the active region 111 cannot be completely removed after the etching process.

Finally, a conductive plug 130 and a conductive layer 140 are sequentially formed on the active region 111 . When there is an abnormality in the process of forming the barrier layer, resulting in photoresist residue, and further causing the metal silicide barrier on the active region to not be completely removed, it will inevitably lead to the subsequent formation of conductive plugs, and active plugs. There is an abnormality in the electrical connection of the area, such as the area of the connection is too small or it cannot be connected to the active area.

It can be seen that when the reliability test structure formed above is tested, the connection status between the active region and the conductive plug can be judged according to the test result, and then it can be deduced whether there is any abnormality in the process of forming the barrier layer.

Embodiment two

Fig. 2A is a schematic diagram of the reliability testing structure of the second embodiment of the utility model, and Fig. 2B is a cross-sectional view of the reliability testing structure of the second embodiment of the utility model along the direction AA'. As shown in FIG. 2A and FIG. 2B, in this embodiment, the reliability test structure includes: a substrate, a barrier layer 220, a conductive plug 230, and a conductive layer 240, and a plurality of active regions are formed in the substrate. 211 and an isolation structure 212, the barrier layer 220 is formed on the isolation structure 212, a conductive plug 230 is formed at both ends of each active region 211, and the conductive layer 140 is formed on the conductive plug 230 above. In this embodiment, among the four conductive plugs 230 on two adjacent active regions 211, the two conductive plugs 230 on different active regions 211 are connected to the same conductive layer 240, so that the The active region 211 , the conductive plug 230 and the conductive layer 240 form a chain structure connected in series.

In this embodiment, the active region, the conductive plug and the conductive layer are a chain structure connected in series, and when the resistance test is performed on the reliability test structure, a voltage is applied to the first and last ends of the chain structure or current, and then according to the detected corresponding current value or voltage value, the resistance value of the series-connected structure can be obtained, and the active region in the chain structure can be judged according to the obtained resistance value. The connection status of the conductive plugs can be used to judge whether there is a barrier layer left on the active area. That is, by using the reliability test structure provided by the utility model, the abnormality monitoring of the formation process of the barrier layer can be carried out.

The active regions 211 can be arranged in any shape to form a linear structure, for example arranged in an L-shape, U-shape, M-shape or W-shape linearly or in a meandering way to form a serpentine structure. In this embodiment, each active region 211 is a strip structure, and multiple active regions are arranged in a meandering manner to form a serpentine structure. Specifically, the active regions 211 are arranged with different serpentine pitches, that is, the serpentine structure has multiple different serpentine pitches. Preferably, the detour pitch can be multiplied according to the minimum design size. As shown in FIG. 2A , in this embodiment, the active regions 211 are arranged with 5 different detour pitches, and the detour pitches are respectively equal to : Minimum design size W1, 2 times the minimum design size W2, 3 times the minimum design size W3, 4 times the minimum design size W4, and 5 times the minimum design size W5.

In the reliability test structure of the present embodiment, the active regions 211 are arranged with different detour pitches to form arrangements with different densities, that is, the widths of barrier layers formed subsequently are also different. During the photolithography process, the depth of focus is different when exposing dense areas and sparse areas, resulting in different exposure accuracy. Therefore, in the subsequent photolithography process for forming barrier layers, the barrier layers formed by dense areas and sparse areas The resolutions are different, so that under the current exposure conditions, the photolithography process window of the width of the barrier layer can be found.

The above description is only a description of the preferred embodiments of the present utility model, and is not any limitation to the scope of the present utility model. Any changes and modifications made by those of ordinary skill in the field of the utility model according to the above disclosures all belong to the protection scope of the claims .

Claims (10)

1. a reliability testing structure, for monitoring the photoresist residual in the forming process of barrier layer Situation, it is characterised in that including: substrate, barrier layer, conductive layer and at least two conductive plunger, Described substrate is formed at least one active area and is positioned at the isolation junction of each described active area periphery Structure, described barrier layer is formed on described isolation structure, and the two ends of each described active area are respectively formed At least one described conductive plunger, described conductive layer is formed at the top of described conductive plunger, is positioned at same The conductive layer that on one active area two ends, conductive plunger is different from two respectively connects, so that described active area, Conductive plunger and conductive layer form the structure of series connection.

2. reliability testing structure as claimed in claim 1, it is characterised in that: shape in described substrate Cheng Youyi active area, the two ends of described active area are respectively formed a conductive plunger.

3. reliability testing structure as claimed in claim 1, it is characterised in that: shape in described substrate Become to have multiple active area, the two ends of each described active area are respectively formed a conductive plunger, adjacent Two active areas on four conductive plungers in, two conductive plungers being positioned on different active area are even It is connected on same conductive layer.

4. reliability testing structure as claimed in claim 3, it is characterised in that: multiple described active District is arranged in a serpentine configuration in the way of roundabout.

5. reliability testing structure as claimed in claim 4, it is characterised in that: described serpentine configuration There is multiple different roundabout spacing.

6. reliability testing structure as claimed in claim 5, it is characterised in that: described roundabout spacing For being doubled and redoubled according to minimum design dimension.

7. reliability testing structure as claimed in claim 3, it is characterised in that: multiple described active District arranges L-shaped, U-shaped, M type or W shape.

8. reliability testing structure as claimed in claim 1, it is characterised in that: described active area It is shaped as bar shaped.

9. reliability testing structure as claimed in claim 8, it is characterised in that: described active area Width is more than or equal to minimum design dimension.

10. reliability testing structure as claimed in claim 1, it is characterised in that: described conduction is inserted Plug is more than or equal to minimum design dimension with the spacing of described isolation structure.