Method for monitoring coating uniformity of photoresist structure

Abstract

The invention provides a method for monitoring the coating uniformity of a photoresist structure, and the method comprises the steps: obtaining the first film thickness data of the photoresist structure on a bare chip through a set coating program, and then obtaining the first film thickness data of the photoresist structure on the bare chip after determining that the coating uniformity of the photoresist structure of the coating program is qualified; the method comprises the following steps of: coating a photoresist structure on a wafer on which a concave pattern is formed through a coating formula, then carrying out OCD measurement on the photoresist structure on the wafer to obtain second film thickness data of the photoresist structure, and finally judging whether the coating uniformity of the photoresist structure on the wafer is qualified or not by comparing the first film thickness data with the second film thickness data. According to the invention, the OCD measures the second film thickness data of a plurality of repeated photoresist structures coated on the surface of the active region of the wafer with the concave pattern, and compares the first film thickness data of the photoresist on the bare chip with the second film thickness data of the photoresist on the wafer with the concave pattern. And whether the coating uniformity of the photoresist structure on the surface of the wafer and the filling uniformity of the concave pattern are qualified or not can be accurately judged.

Description

Technical Field

[0001] The present application relates to the field of semiconductor manufacturing technology, and in particular to a method for monitoring the coating uniformity of a photoresist structure. Background Art

[0002] During the semiconductor manufacturing process, grooves or step patterns are usually formed in the wafer (substrate). In some key photolithography processes, it is necessary to ensure that the wafer surface is flat. Photoresist materials are often used to fill the grooves or steps by spin coating to flatten the wafer surface.

[0003] At present, the thickness of the film monitored by lithography is mainly confirmed on the bare die (wafer / substrate without any pattern formed by lithography), and the coating uniformity of the photoresist material spin-coated on the surface of the wafer with grooves or steps is mainly confirmed by slicing. The film thickness of the photoresist material on the surface of the wafer with grooves or steps is confirmed. However, the method of confirming the film thickness by slicing has certain limitations. The slicing method can only confirm individual areas and individual positions, and the authenticity of the photoresist slicing is poor, especially for some wafers with high step differences or deep grooves. When affected by the load effect / loading effect and other factors affecting the coating performance, the coating uniformity of the photoresist material cannot be confirmed. Summary of the invention

[0004] The present application provides a method for monitoring the coating uniformity of a photoresist structure, which can solve the problem that a slicing method cannot accurately confirm the coating uniformity of a photoresist material spin-coated on a wafer surface having grooves or steps.

[0005] The present application embodiment provides a method for monitoring the coating uniformity of a photoresist structure, comprising: The first step: establish a coating process for a photoresist structure of a certain thickness; The second step: providing a bare chip, and coating the photoresist structure on the bare chip according to the coating procedure; The third step: performing optical critical dimension measurement on the photoresist structure on the surface of the die according to the spectrum information of the photoresist structure on the surface of the die, and obtaining first film thickness data of a plurality of points of the photoresist structure on the surface of the die in various directions; Step 4: judging whether the coating uniformity of the coating process on the surface of the die is qualified according to the first film thickness data; Step 5: If it is confirmed that the coating uniformity of the coating process on the surface of the die is qualified, a wafer with a plurality of recessed patterns formed thereon is provided, and the photoresist structure is coated on the wafer according to the coating process, wherein the photoresist structure fills the recessed patterns and covers the surface of the wafer; Step 6: performing optical critical dimension measurement on the photoresist structure on the wafer surface according to the spectrum information of the photoresist structure on the wafer surface where the recessed patterns are formed, and obtaining second film thickness data of the photoresist structure on the wafer surface between the recessed patterns; Step 7: Compare the first film thickness data with the second film thickness data to determine whether the coating uniformity of the photoresist structure on the surface of the wafer is qualified.

[0006] Optionally, in the method for monitoring coating uniformity of a photoresist structure, the fourth step comprises: Obtaining a first difference between a maximum value and a minimum value in the first film thickness data; If the first difference between the maximum value and the minimum value in the first film thickness data is not greater than 1% of the spin-coated thickness of the photoresist structure in the second step, it is confirmed that the coating process is uniformly coated on the surface of the bare chip; if the first difference between the maximum value and the minimum value in the first film thickness data is greater than 1% of the spin-coated thickness of the photoresist structure in the second step, it is confirmed that the coating process is unevenly coated on the surface of the bare chip.

[0007] Optionally, in the method for monitoring the coating uniformity of the photoresist structure, if it is confirmed that the coating process is not uniform on the surface of the die, the second step is returned to be executed.

[0008] Optionally, in the method for monitoring coating uniformity of a photoresist structure, the seventh step comprises: Respectively obtaining a first difference between a maximum value and a minimum value in the first film thickness data, and a second difference between a maximum value and a minimum value in the second film thickness data; Compare the first difference and the second difference. If the difference between the first difference and the second difference is not greater than 1% of the spin-coated thickness of the photoresist structure in the fifth step, it is confirmed that the coating of the photoresist structure on the surface of the wafer with the recessed pattern is uniform; if the difference between the first difference and the second difference is greater than 1% of the spin-coated thickness of the photoresist structure in the fifth step, it is confirmed that the coating of the photoresist structure on the surface of the wafer with the recessed pattern is uneven.

[0009] Optionally, in the method for monitoring coating uniformity of a photoresist structure, the seventh step comprises: Obtaining a second difference between the maximum value and the minimum value in the second film thickness data; Compare the first difference and the second difference. If the difference between the first difference and the second difference is not greater than 1% of the spin-coated thickness of the photoresist structure in the fifth step, it is confirmed that the coating of the photoresist structure on the surface of the wafer with the recessed pattern is uniform; if the difference between the first difference and the second difference is greater than 1% of the spin-coated thickness of the photoresist structure in the fifth step, it is confirmed that the coating of the photoresist structure on the surface of the wafer with the recessed pattern is uneven.

[0010] Optionally, in the method for monitoring coating uniformity of a photoresist structure, the photoresist structure is a spin-coated carbon material.

[0011] Optionally, in the method for monitoring the coating uniformity of the photoresist structure, in establishing a coating procedure for the photoresist structure, the spin coating thickness of the photoresist structure selected is 1500Å~5000Å.

[0012] Optionally, in the method for monitoring coating uniformity of a photoresist structure, the recessed pattern is any one of a deep groove pattern, a shallow groove pattern or a step pattern.

[0013] Optionally, in the method for monitoring the coating uniformity of the photoresist structure, the first film thickness data at least includes: film thickness values ​​of 49 points of the photoresist structure on the surface of the die in various directions.

[0014] Optionally, in the method for monitoring the coating uniformity of the photoresist structure, the second film thickness data at least includes: film thickness values ​​of 49 points of the photoresist structure on the wafer surface between the recessed patterns in various directions.

[0015] The technical solution of this application has at least the following advantages: The present application first obtains the first film thickness data of the photoresist structure on the surface of the bare chip at multiple points in various directions through a set coating program, and then after confirming that the coating uniformity of the photoresist structure of the coating program is qualified, the photoresist structure is coated on a wafer with several recessed patterns formed thereon through the coating program, and then the photoresist structure on the surface of the wafer is optically critical dimensioned based on the spectral information of the photoresist structure on the surface of the wafer with recessed patterns formed thereon, and the second film thickness data of the photoresist structure is obtained, and finally, by comparing the first film thickness data and the second film thickness data, it is determined whether the coating uniformity of the photoresist structure on the surface of the wafer is qualified. The present application measures the second film thickness data of several repeated photoresist structures coated on the active area surface of the wafer with recessed patterns by OCD (optical critical dimension), and by comparing the first film thickness data of the photoresist on the bare chip and the second film thickness data of the photoresist on the wafer with recessed patterns, the coating uniformity of the photoresist structure on the surface of the wafer and the recessed pattern filling uniformity can be accurately, effectively and intuitively monitored. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 is a flow chart of a method for monitoring coating uniformity of a photoresist structure according to an embodiment of the present invention; Figure 2 is a schematic diagram of a semiconductor structure in which a photoresist structure is coated on a bare chip according to an embodiment of the present invention; Figure 3 It is a schematic diagram of a semiconductor structure in which a photoresist structure is coated on a wafer having a deep groove pattern formed thereon according to an embodiment of the present invention; The reference numerals are described as follows: 11 - bare die, 12 - wafer, 13 - deep groove pattern, 21 - photoresist structure spun on the bare die surface, 22 - photoresist structure 22 spun on the wafer surface with deep grooves. DETAILED DESCRIPTION

[0018] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0019] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0020] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0021] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0022] The present application provides a method for monitoring the coating uniformity of a photoresist structure, referring to Figure 1 , Figure 1 1 is a flow chart of a method for monitoring coating uniformity of a photoresist structure according to an embodiment of the present invention. The method for monitoring coating uniformity of a photoresist structure includes: First, a first step S1 is performed: a coating process of a photoresist structure with a certain thickness is established.

[0023] Preferably, in the coating process of establishing the photoresist structure, the spin coating thickness of the photoresist structure is selected to be 1500Å~5000Å.

[0024] In this embodiment, the spin coating thickness of the photoresist structure can be set to 3000Å.

[0025] Preferably, the photoresist structure is a spin-on carbon material (SOC).

[0026] Then, the second step S2 is performed: referring to Figure 2 , Figure 2 1 is a schematic diagram of a semiconductor structure in which a photoresist structure is coated on a bare chip according to an embodiment of the present invention. A bare chip 11 is provided, and the photoresist structure 21 is coated on the bare chip 11 according to the coating process.

[0027] Next, execute the third step S3: perform optical critical dimension measurement (OCD measurement) on the photoresist structure 21 on the surface of the die 11 according to the spectral information of the photoresist structure on the surface of the die 11 collected in advance, and obtain first film thickness data of multiple points of the photoresist structure 21 on the surface of the die 11 in various directions.

[0028] Preferably, the first film thickness data at least includes: film thickness values ​​D1 of 49 points of the photoresist structure on the surface of the die 11 in various directions.

[0029] It is worth noting that the spectral information of the photoresist structure on the surface of the bare chip 11 must be the spectral information of the photoresist structure on the surface of the bare chip 11. As to whether it is the spectral information of the photoresist structure on the surface of the bare chip of this batch or the spectral information of the photoresist structure on the surface of the bare chip of the previous batch, this application does not limit it.

[0030] Furthermore, a fourth step S4 is performed: judging whether the coating uniformity of the coating process on the surface of the die 11 is qualified according to the first film thickness data.

[0031] Preferably, the fourth step S4 comprises: S4.1 obtain a first difference between a maximum value and a minimum value in the first film thickness data; S4.2 If the first difference between the maximum value and the minimum value in the first film thickness data is not greater than 1% of the spin-coated thickness of the photoresist structure in the second step S2, it is confirmed that the coating process is uniformly coated on the surface of the bare chip 11; if the first difference between the maximum value and the minimum value in the first film thickness data is greater than 1% of the spin-coated thickness of the photoresist structure in the second step S2, it is confirmed that the coating process is unevenly coated on the surface of the bare chip 11.

[0032] It is worth noting that if it is confirmed that the coating process is not uniform on the surface of the die 11, the second step S2 is returned to be executed. If it is confirmed that the coating process is uniform on the surface of the die 11, the fifth step S5 is continued to be executed.

[0033] Next, the fifth step S5 is performed: referring to Figure 3 , Figure 3 It is a schematic diagram of a semiconductor structure in which a photoresist structure is coated on a wafer having a deep groove pattern according to an embodiment of the present invention. If it is confirmed that the coating uniformity of the coating procedure on the surface of the bare chip 11 is qualified, a wafer 12 having a plurality of recessed patterns is provided, and the photoresist structure 22 is coated on the wafer 12 according to the coating procedure, wherein the photoresist structure 22 fills the recessed patterns and covers the surface of the wafer 12.

[0034] Preferably, the concave pattern is any one of a deep groove pattern, a shallow groove pattern or a step pattern.

[0035] In this embodiment, the recessed pattern is a deep groove pattern 13 .

[0036] Due to the same coating procedure, the spin coating thickness of the photoresist structure in the second step S2 is the same as the spin coating thickness of the photoresist structure in the second step S5.

[0037] Further, the sixth step S6 is performed: based on the spectral information of the photoresist structure on the surface of the wafer 12 where the deep groove pattern 13 is formed, optical critical dimension measurement (OCD measurement) is performed on the photoresist structure 22 on the surface of the wafer 12 to obtain second film thickness data of the photoresist structure on the surface of the wafer between the recessed patterns.

[0038] The second film thickness data at least includes: film thickness values ​​D2 of 49 points of the photoresist structure on the wafer surface between the deep groove patterns 13 in various directions.

[0039] It is worth noting that the spectral information of the photoresist structure on the surface of the wafer 12 with the deep groove pattern 13 must be the spectral information of the photoresist structure on the surface of the wafer 12 with the deep groove pattern 13. As to whether it is the spectral information of the photoresist structure on the surface of the wafer 12 with the deep groove pattern 13 of this batch or the spectral information of the photoresist structure on the surface of the wafer 12 with the same deep groove pattern 13 of the previous batch, this application does not limit it.

[0040] Finally, the seventh step S7 is performed: comparing the first film thickness data with the second film thickness data to determine whether the coating uniformity of the photoresist structure 22 on the surface of the wafer 12 is qualified.

[0041] The seventh step S7 comprises: S7.1: Obtain a second difference between the maximum value and the minimum value in the second film thickness data; S7.2: Compare the first difference and the second difference. If the difference between the first difference and the second difference is not greater than 1% of the spin-coated thickness of the photoresist structure in the fifth step S5, it is confirmed that the coating of the photoresist structure 22 on the surface of the wafer 12 with the deep groove pattern 13 is uniform; if the difference between the first difference and the second difference is greater than 1% of the spin-coated thickness of the photoresist structure in the fifth step S5, it is confirmed that the coating of the photoresist structure 22 on the surface of the wafer 12 with the deep groove pattern 13 is uneven.

[0042] In the present application, the first film thickness data of the photoresist structure on the surface of the bare chip at multiple points in various directions is first obtained through a set coating program, and then after confirming that the coating uniformity of the photoresist structure of the coating program is qualified, the photoresist structure is coated on a wafer with several recessed patterns formed thereon through the coating program, and then the photoresist structure on the surface of the wafer is optically critical dimensioned according to the spectral information of the photoresist structure on the surface of the wafer with recessed patterns formed thereon, and the second film thickness data of the photoresist structure is obtained, and finally, by comparing the first film thickness data and the second film thickness data, it is determined whether the coating uniformity of the photoresist structure on the surface of the wafer is qualified. The present application measures the second film thickness data of several repeated photoresist structures coated on the active area surface of a wafer with recessed patterns by OCD (optical critical dimension), and by comparing the first film thickness data of the photoresist on the bare chip and the second film thickness data of the photoresist on the wafer with recessed patterns, it is possible to accurately determine whether the coating uniformity of the photoresist structure on the surface of the wafer and the recessed pattern filling uniformity are qualified. Compared with the traditional method of monitoring the film thickness uniformity of photoresist materials on the surface of a wafer with grooves or steps by slicing, the method for monitoring the coating uniformity of a photoresist structure provided in the present application is more accurate, more effective, and more intuitive.

[0043] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection created by this application.

Claims

1. A method for monitoring the coating uniformity of a photoresist structure, characterized in that: include: The first step: establish a coating process for a photoresist structure of a certain thickness; The second step: providing a bare chip, and coating the photoresist structure on the bare chip according to the coating procedure; The third step: performing optical critical dimension measurement on the photoresist structure on the surface of the die according to the spectrum information of the photoresist structure on the surface of the die, and obtaining first film thickness data of a plurality of points of the photoresist structure on the surface of the die in various directions; Step 4: judging whether the coating uniformity of the coating process on the surface of the die is qualified according to the first film thickness data; Step 5: If it is confirmed that the coating uniformity of the coating process on the surface of the die is qualified, a wafer with a plurality of recessed patterns formed thereon is provided, and the photoresist structure is coated on the wafer according to the coating process, wherein the photoresist structure fills the recessed patterns and covers the surface of the wafer; Step 6: performing optical critical dimension measurement on the photoresist structure on the wafer surface according to the spectrum information of the photoresist structure on the wafer surface where the recessed patterns are formed, and obtaining second film thickness data of the photoresist structure on the wafer surface between the recessed patterns; Step 7: Compare the first film thickness data with the second film thickness data to determine whether the coating uniformity of the photoresist structure on the surface of the wafer is qualified.

2. The method for monitoring coating uniformity of a photoresist structure according to claim 1, characterized in that: The fourth step comprises: Obtaining a first difference between a maximum value and a minimum value in the first film thickness data; If the first difference between the maximum value and the minimum value in the first film thickness data is not greater than 1% of the spin-coated thickness of the photoresist structure in the second step, it is confirmed that the coating process is uniformly coated on the surface of the bare chip; if the first difference between the maximum value and the minimum value in the first film thickness data is greater than 1% of the spin-coated thickness of the photoresist structure in the second step, it is confirmed that the coating process is unevenly coated on the surface of the bare chip.

3. The method for monitoring coating uniformity of a photoresist structure according to claim 2, characterized in that: If it is confirmed that the coating process is not uniform on the surface of the die, the second step is returned to be executed.

4. The method for monitoring coating uniformity of a photoresist structure according to claim 1, characterized in that: The seventh step comprises: Respectively obtaining a first difference between a maximum value and a minimum value in the first film thickness data, and a second difference between a maximum value and a minimum value in the second film thickness data; Compare the first difference and the second difference. If the difference between the first difference and the second difference is not greater than 1% of the spin-coated thickness of the photoresist structure in the fifth step, it is confirmed that the coating of the photoresist structure on the surface of the wafer with the recessed pattern is uniform; if the difference between the first difference and the second difference is greater than 1% of the spin-coated thickness of the photoresist structure in the fifth step, it is confirmed that the coating of the photoresist structure on the surface of the wafer with the recessed pattern is uneven.

5. The method for monitoring coating uniformity of a photoresist structure according to claim 2, characterized in that: The seventh step comprises: Obtaining a second difference between the maximum value and the minimum value in the second film thickness data; Compare the first difference and the second difference. If the difference between the first difference and the second difference is not greater than 1% of the spin-coated thickness of the photoresist structure in the fifth step, it is confirmed that the coating of the photoresist structure on the surface of the wafer with the recessed pattern is uniform; if the difference between the first difference and the second difference is greater than 1% of the spin-coated thickness of the photoresist structure in the fifth step, it is confirmed that the coating of the photoresist structure on the surface of the wafer with the recessed pattern is uneven.

6. The method for monitoring coating uniformity of a photoresist structure according to claim 1, characterized in that: The photoresist structure is a spin-coated carbon material.

7. The method for monitoring coating uniformity of a photoresist structure according to claim 1, characterized in that: In the coating process of establishing the photoresist structure, the spin coating thickness of the photoresist structure is selected to be 1500Å~5000Å.

8. The method for monitoring coating uniformity of a photoresist structure according to claim 1, characterized in that: The concave pattern is any one of a deep groove pattern, a shallow groove pattern or a step pattern.

9. The method for monitoring coating uniformity of a photoresist structure according to claim 1, characterized in that: The first film thickness data at least includes: film thickness values ​​of 49 points of the photoresist structure on the surface of the die in various directions.

10. The method for monitoring coating uniformity of a photoresist structure according to claim 1, characterized in that: The second film thickness data at least includes: film thickness values ​​of 49 points of the photoresist structure on the wafer surface between the recessed patterns in various directions.

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