Process monitoring energy stability method

Abstract

The invention discloses a method for monitoring energy stability by a process. The method comprises the following steps: S1, providing a wafer; s2, coating positive glue; s3, positive photoresist exposure is conducted, mask-free stepping exposure is adopted, the exposure dose is D + / -delta d, D is the normal exposure dose, delta d is the exposure dose variation, the imaging focal length is constant, stepping exposure is conducted according to grids arranged in rows and columns, in all the rows to be exposed, only one grid in the middle position of the uppermost row is exposed, and the positive photoresist is exposed; all the grids in the rest rows need to be exposed, the grids in the middle positions of all the rows are located in the same column, in the corresponding rows to be exposed, the exposure dose of the grids in the middle positions is D, the exposure dose is gradually increased by delta d when stepping rightwards, and the exposure dose is gradually decreased by delta d when stepping leftwards; s4, developing the positive photoresist by using a positive photoresist developing solution, wherein the developed region is just in the middle column containing the column reference position; and S5, performing regular monitoring, and if the developed region of the middle column is monitored to float leftwards or rightwards after regular monitoring, indicating that the energy fluctuates.

Description

Technical Field

[0001] The present disclosure relates to the semiconductor field, and more particularly to a method for process monitoring energy stability. Background Art

[0002] Photolithography is an important micro-nano manufacturing technology, widely used in integrated circuits, optical devices and other fields. In the exposure process of photolithography, the stability of light source energy plays a vital role in exposure quality and device performance. If the light source energy is unstable, it will lead to uneven sensitivity of the exposure agent, which will cause insufficient reaction of the exposure agent or overexposure, thus affecting the brightness and resolution of the device. Therefore, it is very important to develop a method to monitor the stability of the light source energy of the photolithography machine. Summary of the invention

[0003] In view of the problems existing in the background technology, an object of the present disclosure is to provide a method for process monitoring energy stability, which can stabilize the energy of the light source of a lithography machine.

[0004] Therefore, a method for process monitoring energy stability includes the following steps: S1, providing a wafer as a semiconductor substrate that has not been subjected to any process; S2, applying a positive photoresist on the surface of the wafer; S3, exposing the positive photoresist, using a maskless stepping exposure, the exposure dose is D±Δd, wherein D is a normal exposure dose, Δd is an exposure dose variation, the imaging focal length is constant, the stepping exposure is performed on the wafer surface in grids arranged in rows and columns, among all the rows to be exposed, only one grid in the middle position of the top row is exposed, and all the grids in the remaining rows are to be exposed, the grids in the middle position of each row are in the same column, and in the corresponding row where all the grids are to be exposed, the exposure dose of the grid in the middle position is D, and the exposure dose increases by Δd when stepping to the right to the next grid, and increases by Δd when stepping to the left to the next grid. The exposure dose is decreased by Δd. First, the middle grid of the top row as the column reference position is exposed. Then, the first row adjacent to the top row is exposed from left to right. Subsequently, after the first row is exposed, the second row adjacent to the first row is exposed from right to left. Then, after the second row is exposed, the third row adjacent to the second row is exposed from left to right. This process is repeated until the last row is exposed. The path formed by the stepping exposure from the first row to the last row is serpentine. S4: positive photoresist is developed using a positive photoresist developer. The developed area is exactly in the middle column containing the column reference position. S5: the middle column is used as the judgment standard for regular monitoring. If the developed area of ​​the middle column drifts to the left or right after regular monitoring, it means that the energy fluctuates.

[0005] The beneficial effects of the present disclosure are as follows: In the method for monitoring energy stability of the process according to the present disclosure, through steps S2 to S4, the developed area is exactly in the middle column containing the column reference position, and through step S5, the middle column is used as the judgment standard for regular monitoring. If the developed area of ​​the middle column drifts to the left or right area after regular monitoring, it means that the energy fluctuates. Such energy fluctuations may occur, for example, when the lithography machine is used again after a long-term shutdown, when the lithography machine is used to the second half of its life, and when the workshop environment fluctuates (electromagnetic field, temperature, humidity, etc.). Further, if the range of drifting to the left or right area exceeds the prescribed range, it means that the operation of the lithography machine (including the light source energy) will become unstable, which will affect the stability of the product quality. At this time, the staff needs to check the lithography machine and the workshop working environment and take corresponding solutions. After the solution is completed, the method for monitoring energy stability of the process disclosed in the present disclosure can be executed again until there is no drift or the range of drifting to the left or right area does not exceed the prescribed range, so that the lithography machine (including the light source) can be put into product production normally. The specified scope is determined based on the product requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a flow chart of a method of monitoring energy stability according to a process of the present disclosure.

[0007] Figure 2 This is the layout of the grid to be exposed and the exposure dose in step S3 of Example 1.

[0008] Figure 3 These are different development states when step S5 of Example 1 is completed and when step S6 is performed. DETAILED DESCRIPTION

[0009] It will be understood that the disclosed embodiments are merely examples of the present disclosure, which may be implemented in various forms, and therefore, the specific details disclosed herein should not be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one of ordinary skill in the art to implement the present disclosure in various ways.

[0010] [Method for process monitoring energy stability]

[0011] Reference Figures 1 to 3 , the method for monitoring energy stability according to the process disclosed in the present invention comprises the steps of:

[0012] S1, providing a wafer as a semiconductor substrate that has not undergone any process;

[0013] S2, coating positive resist on the surface of the wafer;

[0014] S3, expose the positive photoresist,

[0015] The maskless stepping exposure is adopted, and the exposure dose is D±Δd, where D is the normal exposure dose, Δd is the exposure dose variation, the imaging focal length is constant, and the stepping exposure is arranged in rows and columns on the wafer surface. Figure 2 In all rows to be exposed, only the middle grid of the top row is exposed, and all the grids of the remaining rows are exposed. The grids in the middle of each row are in the same column. In the corresponding row where all the grids are to be exposed, the exposure dose of the grid in the middle is D. When stepping to the right to the next grid, the exposure dose increases by Δd, and when stepping to the left to the next grid, the exposure dose decreases by Δd. Figure 2 The corresponding grid numbers in the right figure indicate that

[0016] First, the middle grid of the top row, which is the column reference position, is exposed. Then, the first row adjacent to the top row is exposed step by step from left to right.

[0017] Then, after the first row is exposed, the second row adjacent to the first row is exposed step by step from right to left.

[0018] Then, after the second row is exposed, the third row adjacent to the second row is exposed from left to right, and so on, until the last row is exposed.

[0019] The path formed by the exposure is serpentine;

[0020] S4, developing the positive photoresist with a positive photoresist developer, wherein the developed area is located exactly in the middle column containing the column reference position;

[0021] S5, taking the middle column as the judgment standard, regular monitoring is performed. If the developed area in the middle column drifts to the left or right area after regular monitoring, it means that energy fluctuation occurs.

[0022] In the method for monitoring energy stability of the process disclosed in the present invention, through steps S2 to S4, the developed area is exactly in the middle column containing the column reference position, and through step S5, the middle column is used as the judgment standard for regular monitoring. If the developed area of ​​the middle column drifts to the left or right area after regular monitoring, it means that the energy fluctuates. This energy fluctuation may occur, for example, when the lithography machine is used again after a long-term shutdown, when the lithography machine is used to the second half of its life, and when the workshop environment fluctuates (electromagnetic field, temperature, humidity, etc.). Further, if the range of drifting to the left or right area exceeds the prescribed range, it means that the operation of the lithography machine (including the light source energy) will become unstable, which will affect the stability of the product quality. At this time, the staff needs to check the lithography machine and the workshop working environment and take corresponding solutions. After the solution is completed, the method for monitoring energy stability of the process disclosed in the present invention can be executed again until there is no drift or the range of drifting to the left or right area does not exceed the prescribed range, and then the lithography machine (including the light source) can be put into product production normally. The prescribed range is determined according to the requirements of the product.

[0023] In step S1 , the wafer may be, but is not limited to, silicon.

[0024] For example, in step S2, the positive photoresist is GKR5315, and the coating thickness of the positive photoresist is In step S3, D is 4.4 mj / cm 2 , Δd is 0.2mj / cm 2 , the imaging focal length is 0 μm; in step S4, the positive photoresist developer is ZX-238, the developing time is 60 s, and the flushing time is 30 s.

[0025] For example, in step S5, the regular period is weekly.

[0026] [test]

[0027] Example 1

[0028] The method for process monitoring energy stability of Example 1 adopts the following steps:

[0029] S1, providing a wafer as a semiconductor substrate that has not been processed in any way, the wafer is silicon;

[0030] S2, apply positive photoresist on the surface of the wafer. The positive photoresist is GKR5315 and the coating thickness is

[0031] S3, expose the positive photoresist,

[0032] The maskless stepping exposure is adopted, and the exposure dose is D±Δd, where D is the normal exposure dose, Δd is the exposure dose variation, the imaging focal length is constant, and the stepping exposure is arranged in rows and columns on the wafer surface. Figure 2 In all rows to be exposed, only the middle grid of the top row is exposed, and all the grids of the remaining rows are exposed. The grids in the middle of each row are in the same column. In the corresponding row where all the grids are to be exposed, the exposure dose of the grid in the middle is D. When stepping to the right to the next grid, the exposure dose increases by Δd, and when stepping to the left to the next grid, the exposure dose decreases by Δd. Figure 2 The corresponding grid numbers in the right figure indicate that D is 4.4 mj / cm 2 , Δd is 0.2mj / cm 2 , the imaging focal length is 0μm,

[0033] First, the middle grid of the top row, which is the column reference position, is exposed. Then, the first row adjacent to the top row is exposed step by step from left to right.

[0034] Then, after the first row is exposed, the second row adjacent to the first row is exposed step by step from right to left.

[0035] Then, after the second row is exposed, the third row adjacent to the second row is exposed from left to right, and so on, until the last row is exposed.

[0036] The path formed by the exposure is serpentine;

[0037] S4, positive photolithography is developed using positive photolithography developer, the positive photolithography developer is ZX-238, the development time is 60s, the flushing time is 30s, and the developed area is exactly in the middle column containing the column reference position, such as Figure 3 As shown in the left figure;

[0038] S5, taking the middle column as the judgment standard, monitor regularly in the workshop environment every week. If the area of ​​the middle column that has been developed drifts to the left or right area after regular monitoring, it means that the energy fluctuates. Figure 3 As shown in the right figure, the area in the middle column of the developed image drifts to the left after regular monitoring. Figure 2 The exposure dose corresponding to the right picture is 4.0mj / cm 2 , indicating that the energy fluctuates.

[0039] from Figure 3 As can be seen from the right figure, the energy fluctuation range is 0.4mj / cm 2 , which does not exceed the ±1.0mj / cm required for stable operation of the lithography machine (including the light source)2 Specified scope.

[0040] The above detailed description is used to describe multiple exemplary embodiments, but this document is not intended to be limited to the explicitly disclosed combinations. Therefore, unless otherwise stated, the various features disclosed herein can be combined together to form multiple additional combinations that are not shown for the sake of simplicity.

Claims

1. A method for process monitoring energy stability, characterized in that: Includes steps: S1, providing a wafer as a semiconductor substrate that has not undergone any process; S2, coating positive resist on the surface of the wafer; S3, expose the positive photoresist, The maskless stepping exposure is adopted, and the exposure dose is D±Δd, where D is the normal exposure dose, Δd is the exposure dose variation, and the imaging focal length is constant. The stepping exposure is performed on the wafer surface in grids arranged in rows and columns. Among all the rows to be exposed, only one grid in the middle position of the top row is exposed, and all the grids in the remaining rows are to be exposed. The grids in the middle position of each row are in the same column. In the corresponding row where all the grids are to be exposed, the exposure dose of the grid in the middle position is D. When stepping to the right to the next grid, the exposure dose will increase by Δd, and when stepping to the left to the next grid, the exposure dose will decrease by Δd. First, exposure is performed from the middle grid of the top row, which is the column reference position. Next, the first row adjacent to the top row is exposed step by step from left to right. Then, after the first row is exposed, the second row adjacent to the first row is exposed step by step from right to left. Then, after the second row is exposed, the third row adjacent to the second row is exposed step by step from left to right, and so on, until the last row is exposed. The path formed by the step exposure from the first row to the last row is serpentine; S4, developing the positive photoresist with a positive photoresist developer, wherein the developed area is located exactly in the middle column containing the column reference position; S5, taking the middle column as the judgment standard, regular monitoring is performed. If the developed area in the middle column drifts to the left or right area after regular monitoring, it means that energy fluctuation occurs.

2. The method for process monitoring energy stability according to claim 1, characterized in that: In step S1 , the wafer is silicon.

3. The method for process monitoring energy stability according to claim 1, characterized in that: In step S2, the positive photoresist is GKR5315, and the coating thickness of the positive photoresist is In step S3, D is 4.4 mj / cm 2 , Δd is 0.2mj / cm 2 , the imaging focal length is 0μm; In step S4, the positive photoresist developer is ZX-238, the developing time is 60 seconds, and the flushing time is 30 seconds.

4. The method for process monitoring energy stability according to claim 1, characterized in that: In step S5, the regular period is weekly.

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