Method for monitoring coating uniformity of photoresist structures

Abstract

The application provides a method for monitoring the coating uniformity of photoresist structures. First, the first film thickness data of the photoresist structures on a wafer is obtained through a set coating process. Then, after confirming that the photoresist structure coating uniformity of the coating process is qualified, the photoresist structures are coated on a wafer with a recess pattern through the coating process. Next, the photoresist structures on the wafer are measured by OCD to obtain the second film thickness data of the photoresist structures. Finally, whether the coating uniformity of the photoresist structures on the wafer is qualified is determined by comparing the first film thickness data and the second film thickness data. The second film thickness data of the repeated photoresist structures coated on the active area surface of the wafer with a recess pattern is obtained by OCD measurement, and whether the coating uniformity and the recess pattern filling uniformity of the photoresist structures on the wafer surface are qualified can be accurately determined by comparing the first film thickness data of the photoresist on the wafer and the second film thickness data of the photoresist on the wafer with a recess pattern.

Description

TECHNICAL FIELD

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

[0002] In the process of semiconductor manufacturing, a trench or a step pattern is usually formed in a wafer (substrate), and in some key photolithography processes, it is necessary to ensure the flatness of the wafer surface, and photoresist material is often used to fill the trench or step in a spin coating manner to planarize the wafer surface.

[0003] At present, the thickness of the photoresist monitoring film is mainly confirmed on a bare chip (a wafer / substrate without any pattern formed by photolithography), and the coating uniformity of the photoresist material spin coated on the wafer surface with a trench or a step is mainly confirmed by slicing, that is, the film thickness of the photoresist material on the wafer surface with a trench or a step is confirmed. However, the slicing method for confirming the film thickness has certain limitations, and 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 difference or deep trench, the coating uniformity of the photoresist material cannot be confirmed due to the influence of the loading effect / loading effect (loading effect) and other factors affecting the coating performance. SUMMARY

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

[0005] The present application provides a method for monitoring the coating uniformity of a photoresist structure, which comprises:

[0006] First step: establishing a coating process of a photoresist structure with a certain thickness;

[0007] Second step: providing a bare chip, and coating the photoresist structure on the bare chip according to the coating process;

[0008] Third step: performing optical critical dimension measurement on the photoresist structure on the surface of the bare chip according to the spectral information of the photoresist structure on the surface of the bare chip, and obtaining first film thickness data of a plurality of point positions of the photoresist structure on the surface of the bare chip in each direction;

[0009] Fourth step: determining whether the coating uniformity of the coating process on the surface of the bare chip is qualified according to the first film thickness data;

[0010] A fifth step: if it is confirmed that the coating process is qualified in coating uniformity on the die surface, a wafer formed with a plurality of recess patterns is provided, and the photoresist structure is coated on the wafer according to the coating process, wherein the photoresist structure fills the recess patterns and covers the surface of the wafer;

[0011] A sixth step: according to the spectral information of the photoresist structure on the wafer surface formed with the recess patterns, the photoresist structure on the wafer surface is optically measured to obtain second film thickness data of the photoresist structure on the wafer surface between the recess patterns;

[0012] A seventh step: comparing the first film thickness data and the second film thickness data to determine whether the coating uniformity of the photoresist structure on the wafer surface is qualified.

[0013] Optionally, in the method for monitoring the coating uniformity of the photoresist structure, the fourth step comprises:

[0014] obtaining a first difference value of the maximum value and the minimum value in the first film thickness data;

[0015] If the first difference value of the maximum value and the minimum value in the first film thickness data is not greater than 1% of the photoresist structure spin coating thickness in the second step, it is confirmed that the coating process is uniform on the die surface; if the first difference value of the maximum value and the minimum value in the first film thickness data is greater than 1% of the photoresist structure spin coating thickness in the second step, it is confirmed that the coating process is not uniform on the die surface.

[0016] 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 die surface, the second step is returned to be executed.

[0017] Optionally, in the method for monitoring the coating uniformity of the photoresist structure, the seventh step comprises:

[0018] respectively obtaining a first difference value of the maximum value and the minimum value in the first film thickness data, and a second difference value of the maximum value and the minimum value in the second film thickness data;

[0019] comparing the first difference value and the second difference value, if the difference value of the first difference value and the second difference value is not greater than 1% of the photoresist structure spin coating thickness in the fifth step, it is confirmed that the coating of the photoresist structure on the wafer surface formed with the recess patterns is uniform; if the difference value of the first difference value and the second difference value is greater than 1% of the photoresist structure spin coating thickness in the fifth step, it is confirmed that the coating of the photoresist structure on the wafer surface formed with the recess patterns is not uniform.

[0020] Optionally, in the method for monitoring the coating uniformity of the photoresist structure, the seventh step comprises:

[0021] obtaining a second difference value between the maximum value and the minimum value in the second film thickness data;

[0022] comparing the first difference value and the second difference value, if the difference value between the first difference value and the second difference value is not greater than 1% of the photoresist structure spin coating thickness in the fifth step, it is confirmed that the photoresist structure on the wafer surface with the recess pattern is coated uniformly; if the difference value between the first difference value and the second difference value is greater than 1% of the photoresist structure spin coating thickness in the fifth step, it is confirmed that the photoresist structure on the wafer surface with the recess pattern is not coated uniformly.

[0023] Optionally, in the method for monitoring the coating uniformity of the photoresist structure, the photoresist structure is a spin-on carbon material.

[0024] Optionally, in the method for monitoring the coating uniformity of the photoresist structure, in the process of establishing the photoresist structure coating program, the spin coating thickness of the photoresist structure is selected to be 1500-5000 angstroms.

[0025] Optionally, in the method for monitoring the coating uniformity of the photoresist structure, the recess pattern is any one of a deep trench pattern, a shallow trench pattern or a step pattern.

[0026] Optionally, in the method for monitoring the coating uniformity of the photoresist structure, the first film thickness data at least includes the film thickness values of 49 points in each direction of the photoresist structure on the die surface.

[0027] Optionally, in the method for monitoring the coating uniformity of the photoresist structure, the second film thickness data at least includes the film thickness values of 49 points in each direction of the photoresist structure on the wafer surface between the recess patterns.

[0028] The technical scheme of the present application has at least the following advantages:

[0029] The application firstly obtains first film thickness data of a plurality of points of a photoresist structure on a die surface in various directions through a set coating process, then after confirming that the photoresist structure coating uniformity of the coating process is qualified, the photoresist structure is coated on a wafer with a plurality of recess patterns through the coating process, then the photoresist structure on the wafer surface with the recess patterns is optically measured according to the spectral information of the photoresist structure on the wafer surface with the recess patterns, second film thickness data of the photoresist structure is obtained, and finally whether the coating uniformity of the photoresist structure on the wafer surface is qualified is judged by comparing the first film thickness data and the second film thickness data. The second film thickness data of the plurality of repeated photoresist structures coated on the active area surface of the wafer with the recess patterns is measured by OCD (optical critical dimension), and the coating uniformity and the recess pattern filling uniformity of the photoresist structure on the wafer surface can be accurately, effectively and intuitively monitored by comparing the first film thickness data of the photoresist on the die and the second film thickness data of the photoresist on the wafer with the recess patterns. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the specific embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0031] Figure 1 is a flow chart of the method for monitoring the coating uniformity of the photoresist structure according to an embodiment of the present application;

[0032] Figure 2 is a semiconductor structure schematic diagram of coating the photoresist structure on the die according to an embodiment of the present application;

[0033] Figure 3 is a semiconductor structure schematic diagram of coating the photoresist structure on the wafer with the deep trench pattern according to an embodiment of the present application;

[0034] Among them, the reference signs are explained as follows:

[0035] 11-die, 12-wafer, 13-deep trench pattern, 21-photoresist structure coated on the die surface, 22-photoresist structure coated on the wafer surface with deep trenches. DETAILED DESCRIPTION

[0036] With reference to the drawings, the technical solutions in the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall into the scope of the present application.

[0037] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0038] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication between two elements, it can be wireless connection, or it can be wired connection. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0039] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as there is no conflict.

[0040] The embodiment of the present application provides a method for monitoring the coating uniformity of a photoresist structure, referring to Figure 1 , Figure 1 is a flowchart of the method for monitoring the coating uniformity of the photoresist structure, and the method for monitoring the coating uniformity of the photoresist structure comprises:

[0041] First, a first step S1 is performed: a coating process of a photoresist structure with a certain thickness is established.

[0042] Preferably, in the establishment of the coating process of the photoresist structure, the spin coating thickness of the photoresist structure is selected to be 1500 Å ~ 5000 Å.

[0043] In the present embodiment, the spin coating thickness of the photoresist structure can be set to 3000 Å.

[0044] Preferably, the photoresist structure is a spin-on carbon material (SOC).

[0045] Then, a second step S2 is performed: referring to the spectrum information of the photoresist structure on the surface of the wafer 11 collected in advance, the photoresist structure 21 on the surface of the wafer 11 is coated according to the coating process. Figure 2 , Figure 2 is a schematic diagram of a semiconductor structure for coating a photoresist structure on a wafer according to an embodiment of the present application, a wafer 11 is provided, and the photoresist structure 21 is coated on the wafer 11 according to the coating process.

[0046] Then, a third step S3 is performed: according to the spectrum information of the photoresist structure on the surface of the wafer 11 collected in advance, optical critical dimension measurement (OCD measurement) is performed on the photoresist structure 21 on the surface of the wafer 11 to obtain first film thickness data of multiple points of the photoresist structure 21 on the surface of the wafer 11 in various directions.

[0047] 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 wafer 11 in various directions.

[0048] It is worth noting that the spectrum information of the photoresist structure on the surface of the wafer 11 collected needs to be the spectrum information of the photoresist structure on the surface of the wafer 11, whether it is the spectrum information of the photoresist structure on the surface of the wafer of this batch or the spectrum information of the photoresist structure on the surface of the wafer of the previous batch is not limited by the present application.

[0049] Further, a fourth step S4 is performed: according to the first film thickness data, it is judged whether the coating uniformity of the coating process on the surface of the wafer 11 is qualified.

[0050] Preferably, the fourth step S4 includes:

[0051] S4.1 obtaining a first difference value of the maximum value and the minimum value in the first film thickness data;

[0052] S4.2 if the first difference value of the maximum value and the minimum value in the first film thickness data is not greater than 1% of the spin coating thickness of the photoresist structure in the second step S2, it is confirmed that the coating process on the surface of the wafer 11 is uniform; if the first difference value of the maximum value and the minimum value in the first film thickness data is greater than 1% of the spin coating thickness of the photoresist structure in the second step S2, it is confirmed that the coating process on the surface of the wafer 11 is not uniform.

[0053] It is worth noting that if it is confirmed that the coating process on the surface of the wafer 11 is not uniform, the second step S2 is returned to be executed; if it is confirmed that the coating process on the surface of the wafer 11 is uniform, the fifth step S5 is continued to be executed.

[0054] Then, a fifth step S5 is performed: referring to the spectrum information of the photoresist structure on the surface of the wafer 11 collected in advance, the photoresist structure 21 on the surface of the wafer 11 is coated according to the coating process. Figure 3 , Figure 3is a semiconductor structure schematic diagram of the present application for coating photoresist structure on wafer with deep trench pattern, if the coating uniformity of the coating process on the surface of the die 11 is qualified, a wafer 12 with several recess patterns is provided, and the photoresist structure 22 is coated on the wafer 12 according to the coating process, wherein the photoresist structure 22 fills the recess pattern and covers the surface of the wafer 12.

[0055] Preferably, the recess pattern is any one of deep trench pattern, shallow trench pattern or step pattern.

[0056] In the present embodiment, the recess pattern is deep trench pattern 13.

[0057] Due to the same coating process, the photoresist structure spin coating thickness in the second step S2 is the same as the photoresist structure spin coating thickness in the second step S5.

[0058] Further, a sixth step S6 is performed: according to the spectrum information of the photoresist structure on the surface of the wafer 12 with deep trench pattern 13 collected in advance, 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 wafer surface between the recess patterns.

[0059] The second film thickness data at least includes film thickness values D2 of 49 points in each direction of the photoresist structure on the wafer surface between the deep trench patterns 13.

[0060] It is worth noting that the spectrum information of the photoresist structure on the surface of the wafer 12 with deep trench pattern 13 collected must be the spectrum information of the photoresist structure on the surface of the wafer 12 with deep trench pattern 13, whether it is the spectrum information of the photoresist structure on the surface of the wafer 12 with deep trench pattern 13 of the present batch or the spectrum information of the photoresist structure on the surface of the wafer 12 with the same deep trench pattern 13 of the previous batch, which is not limited by the present application.

[0061] Finally, a seventh step S7 is performed: comparing the first film thickness data and 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.

[0062] The seventh step S7 includes:

[0063] S7.1: obtaining a second difference value of the maximum value and the minimum value in the second film thickness data;

[0064] S7.2: comparing the first difference value and the second difference value, if the difference between the first difference value and the second difference value is not greater than 1% of the photoresist structure spin coating thickness in the fifth step S5, it is confirmed that the photoresist structure 22 on the wafer 12 surface formed with the deep trench pattern 13 is coated uniformly; if the difference between the first difference value and the second difference value is greater than 1% of the photoresist structure spin coating thickness in the fifth step S5, it is confirmed that the photoresist structure 22 on the wafer 12 surface formed with the deep trench pattern 13 is coated non-uniformly.

[0065] In the present application, first, the first film thickness data of the photoresist structure on the wafer surface in various directions is obtained through the set coating program, then after confirming that the photoresist structure coating uniformity of the coating program is qualified, the photoresist structure is coated on the wafer formed with several recess patterns through the coating program, then the optical key size measurement of the photoresist structure on the wafer surface formed with recess patterns is carried out according to the spectral information of the photoresist structure, the second film thickness data of the photoresist structure is obtained, and finally whether the coating uniformity of the photoresist structure on the wafer surface is qualified is judged by comparing the first film thickness data and the second film thickness data. The second film thickness data of the repeated photoresist structure coated on the active area surface of the wafer with recess patterns is measured by OCD (optical key size) measurement, and by comparing the first film thickness data of the photoresist on the wafer and the second film thickness data of the photoresist on the wafer with recess patterns, whether the coating uniformity and the recess pattern filling uniformity of the photoresist structure on the wafer surface are qualified can be accurately judged. Compared with the traditional way of monitoring the film thickness uniformity of the photoresist material on the wafer surface with trenches or steps by slicing, the method for monitoring the coating uniformity of the photoresist structure provided in the present application is more accurate, more effective, and more intuitive.

[0066] Obviously, the above embodiments are only examples for clearly illustrating, but not limiting the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments need not and cannot be exhausted. The changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A method of monitoring the coating uniformity of a photoresist structure, characterized by, The method comprises the following steps: A first step: establishing a coating process of a photoresist structure with a certain thickness; A second step: providing a wafer and coating the photoresist structure on the wafer according to the coating process; A third step: performing optical critical dimension measurement on the photoresist structure on the wafer surface according to spectral information of the photoresist structure on the wafer surface, to obtain first film thickness data of multiple points of the photoresist structure on the wafer surface in various directions; A fourth step: judging whether the coating uniformity of the coating process on the wafer surface is qualified according to the first film thickness data; A fifth step: if it is confirmed that the coating uniformity of the coating process on the wafer surface is qualified, providing a wafer with a plurality of recessed patterns formed thereon and coating the photoresist structure on the wafer according to the coating process, wherein the photoresist structure fills the recessed patterns and covers the surface of the wafer; A sixth step: performing optical critical dimension measurement on the photoresist structure on the wafer surface with the recessed patterns according to spectral information of the photoresist structure on the wafer surface with the recessed patterns, to obtain second film thickness data of the photoresist structure on the wafer surface between the recessed patterns; A seventh step: comparing the first film thickness data and the second film thickness data to judge whether the coating uniformity of the photoresist structure on the wafer surface is qualified.

2. The method of monitoring coating uniformity of a photoresist structure according to claim 1, wherein, 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 coating thickness of the photoresist structure in the second step, it is confirmed that the coating process on the wafer surface is uniformly coated; 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 coating thickness of the photoresist structure in the second step, it is confirmed that the coating process on the wafer surface is not uniformly coated.

3. The method of monitoring the coating uniformity of a photoresist structure according to claim 2, wherein, If it is confirmed that the coating process on the wafer surface is not uniformly coated, the second step is returned to be executed.

4. The method of claim 1, wherein the monitoring of the uniformity of the coating of the photoresist structure is performed by a method comprising: 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; comparing 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 coating thickness of the photoresist structure in the fifth step, it is confirmed that the photoresist structure on the wafer surface with the recessed patterns is uniformly coated; if the difference between the first difference and the second difference is greater than 1% of the spin coating thickness of the photoresist structure in the fifth step, it is confirmed that the photoresist structure on the wafer surface with the recessed patterns is not uniformly coated.

5. The method of claim 2, wherein the monitoring of the uniformity of the coating of the photoresist structure is performed by a method comprising: The seventh step comprises: obtaining a second difference between a maximum value and a minimum value in the second film thickness data; Comparing 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 thickness of the photoresist structure in the fifth step, it is confirmed that the photoresist structure on the wafer surface with the recessed pattern is coated uniformly; if the difference between the first difference and the second difference is greater than 1% of the thickness of the photoresist structure in the fifth step, it is confirmed that the photoresist structure on the wafer surface with the recessed pattern is coated non-uniformly.

6. The method of monitoring coating uniformity of a photoresist structure according to claim 1, wherein, The photoresist structure is a spin-on carbon material.

7. The method of monitoring coating uniformity of a photoresist structure according to claim 1, wherein, In the establishment of the coating program of the photoresist structure, the selected spin-on thickness of the photoresist structure is 1500Å~5000Å.

8. The method of monitoring coating uniformity of a photoresist structure according to claim 1, wherein, The recessed pattern is any one of a deep trench pattern, a shallow trench pattern or a step pattern.

9. The method of monitoring coating uniformity of a photoresist structure according to claim 1, wherein, The first film thickness data at least includes the film thickness values of 49 points in each direction of the photoresist structure on the die surface.

10. The method of monitoring coating uniformity of a photoresist structure according to claim 1, wherein, The second film thickness data at least includes the film thickness values of 49 points in each direction of the photoresist structure on the wafer surface between the recessed patterns.

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