Photoresist coating method

Abstract

The present application belongs to the field of semiconductor processing technology, and specifically relates to a photoresist coating method, which includes: placing a semiconductor wafer on a loading platform and making the center of the semiconductor wafer directly below the photoresist nozzle; controlling the loading platform to drive the semiconductor wafer to rotate, and controlling the photoresist nozzle to spray photoresist toward the center of the semiconductor wafer; controlling the spraying rate of the photoresist nozzle to gradually increase, and when the spraying rate of the photoresist nozzle reaches a first preset value, controlling the spraying rate of the photoresist nozzle to gradually decrease until the semiconductor wafer is sprayed. According to the photoresist coating method of the present application, since a large amount of photoresist is required in the initial stage of spraying of the semiconductor wafer, and as the sprayed area on the semiconductor wafer increases, the required amount of photoresist gradually decreases, the present application reduces the waste of photoresist by reasonably controlling the spraying rate of the photoresist nozzle.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor processing technology, and specifically relates to a photoresist coating method. Background Art

[0002] This section merely provides background information related to the present disclosure and is not necessarily prior art.

[0003] like Figure 1 and Figure 2 As shown, in the semiconductor photolithography coating process, expensive PR (photoresist 50') is used to coat the wafer 10' by spin coating. During the coating process of the wafer 10', 93% of the photoresist 50' is discarded due to unreasonable spraying rate of the photoresist 50'.

[0004] like Figure 3 As shown, when the photoresist 50' is spin-coated, the semiconductor wafer 10' is circular. If the area to be coated on the surface of the wafer 10' is divided into three coating areas A, B and C, and the radial dimensions of the three coating areas A, B and C are all 50 mm, then it can be known that the area on the wafer 10' that needs to be coated with the photoresist 50' increases in sequence: A, 2500πmm 2 ; B, 7500πmm 2 ; C, 12500πmm 2 .

[0005] The area of ​​region B is three times that of region A, and the area of ​​region C is five times that of region B. Regions A, B, and C of different sizes require different amounts of photoresist. If the same amount of photoresist 50' is sprayed on regions A, B, and C, it will inevitably lead to a waste of photoresist 50'. For example, considering the thickness of the photoresist 50', if it is necessary to spray For a photoresist 50' with a thickness of 1000 Å, 0.07 cc of photoresist 50' is needed. However, in reality, about 1 cc of photoresist 50' is used, and about 93% of the photoresist 50' is discarded and wasted. Summary of the invention

[0006] The first aspect of the present application provides a photoresist coating method, which includes: placing a semiconductor wafer on a loading platform and making the center of the semiconductor wafer directly below a photoresist nozzle; controlling the loading platform to drive the semiconductor wafer to rotate, and controlling the photoresist nozzle to spray photoresist toward the center of the semiconductor wafer; controlling the spraying rate of the photoresist nozzle to gradually increase, and when the spraying rate of the photoresist nozzle reaches a first preset value, controlling the spraying rate of the photoresist nozzle to gradually decrease.

[0007] According to the photoresist coating method of the present application, a large amount of photoresist is required in the initial stage of spraying of the semiconductor wafer, and as the sprayed area on the semiconductor wafer increases, the required amount of photoresist gradually decreases. The present application reduces the amount of photoresist waste by reasonably controlling the spraying rate of the photoresist nozzle. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the specific embodiments below. The accompanying drawings are only used for the purpose of illustrating specific embodiments and are not to be considered as limiting the present application. In addition, the same reference numerals are used throughout the accompanying drawings to represent the same components. Among them:

[0009] Figure 1 It is a structural schematic diagram of a photoresist coating device in the prior art;

[0010] Figure 2 A coordinate diagram of photoresist coating rate in the prior art;

[0011] Figure 3 is a distribution map of the area to be coated on the semiconductor wafer;

[0012] Figure 4 A schematic structural diagram of a photoresist coating device according to an embodiment of the present application;

[0013] Figure 5 A flow chart of a photoresist coating method according to an embodiment of the present application;

[0014] Figure 6 A coordinate diagram of the photoresist coating rate according to an embodiment of the present application.

[0015] Reference numerals:

[0016] 10', wafer; 50', photoresist;

[0017] 10. Semiconductor wafers;

[0018] 20. Photoresist nozzle;

[0019] 30. Loading platform;

[0020] 40. Rotation axis;

[0021] 50. Photoresist. DETAILED DESCRIPTION

[0022] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0023] Various structural schematic diagrams according to embodiments of the present disclosure are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0024] In the context of the present disclosure, when a layer / element is referred to as being "on" another layer / element, the layer / element may be directly on the other layer / element or an intervening layer / element may exist therebetween. In addition, if a layer / element is "on" another layer / element in one orientation, the layer / element may be "below" the other layer / element when the orientation is reversed.

[0025] like Figure 4 and Figure 5 As shown, an embodiment of the present application provides a photoresist coating method, which includes the following steps: S110, placing a semiconductor wafer 10 on a loading platform 30 and making the center of the semiconductor wafer 10 directly below the photoresist nozzle 20; controlling the loading platform 30 to drive the semiconductor wafer 10 to rotate, and controlling the photoresist nozzle 20 to spray photoresist toward the center of the semiconductor wafer 10; controlling the spraying rate of the photoresist nozzle 20 to gradually increase, and when the spraying rate of the photoresist nozzle 20 reaches a first preset value, controlling the spraying rate of the photoresist nozzle 20 to gradually decrease until the semiconductor wafer 10 is completely sprayed.

[0026] According to the photoresist coating method of the present application, by adopting a reasonable spraying rate of the photoresist nozzle 20, the waste amount of the photoresist 50 is reduced. Specifically, since the area to be coated of the semiconductor wafer 10 is circular, if the circular area to be coated is decomposed into a plurality of circular rings with the same radial size, due to the position difference between the plurality of circular rings, the area of ​​the circular ring farther from the center of the semiconductor wafer 10 is larger, and in the process of spraying the photoresist by the photoresist nozzle 20, since the semiconductor wafer 10 is in a state of high-speed rotation, the photoresist 50 sprayed by the photoresist nozzle 20 to the center of the semiconductor wafer 10 will first be thrown to the circular ring at the edge of the semiconductor wafer 10 under the action of centrifugal force, and then the photoresist 50 will be gradually thrown to a position close to the center of the semiconductor wafer 10.

[0027] During the process of the photoresist nozzle 20 spraying the photoresist 50 from the edge of the semiconductor wafer 10 toward the center of the circle, the demand for photoresist 50 gradually decreases. At this time, if the photoresist nozzle 20 adopts a fixed spraying speed to spray the semiconductor wafer 10 during the process of spraying the photoresist 50, there will be a phenomenon of uneven spraying amount in multiple annular areas of multiple circular rings, resulting in different thicknesses in multiple annular areas and waste of photoresist 50.

[0028] In order to reduce the phenomenon of uneven spraying amount in multiple annular areas of the semiconductor wafer 10, the embodiment of the present application proposes a spraying method with a gradually decreasing spraying amount. That is, when spraying photoresist on the annular area at the edge of the semiconductor wafer 10, the spraying rate of the photoresist nozzle 20 can be increased so that a sufficient amount of photoresist can cover the annular area at the edge of the semiconductor wafer 10. When spraying photoresist 50 on the annular area close to the center of the semiconductor wafer 10, the spraying rate of the photoresist nozzle 20 can be reduced, thereby reducing the waste of photoresist 50.

[0029] Furthermore, in order to enable the photoresist to be sprayed onto the semiconductor wafer 10 from the outside to the inside, the embodiment of the present application further proposes adjusting the rotation speed of the loading platform 30 and setting the spray pressure of the photoresist nozzle 20 according to the concentration of the photoresist, so that the photoresist 50 is thrown from the outside to the inside to the to-be-coated area of ​​the semiconductor wafer 10 under the centrifugal force of the semiconductor wafer 10. Specifically, Figure 4 As shown, the photoresist coating equipment includes a loading platform 30, a rotating shaft 40 and a photoresist nozzle 20. The rotating shaft 40 drives the loading platform 30 and the semiconductor wafer 10 on the loading platform 30 to rotate. The rotating shaft 40 is a hollow structure and is connected to a vacuum pump. The photoresist nozzle 20 is located directly above the center of the semiconductor wafer 10. The photoresist 50 sprayed by the photoresist nozzle 20 flows to the center of the semiconductor wafer 10, and then is thrown to the edge of the semiconductor wafer 10 under the centrifugal force of the semiconductor wafer 10, so as to achieve the purpose of fully spraying the semiconductor wafer 10.

[0030] by Figure 3 Taking the semiconductor wafer 10 shown in FIG. 10 as an example, if the area to be coated on the surface of the semiconductor wafer 1010′ is divided into three coating areas A, B and C, and the radial dimensions of the three coating areas A, B and C are all 50 mm, then it can be known that the area on the semiconductor wafer 10 that needs to be coated with the photoresist 50′ increases in sequence: A, 2500πmm 2 ; B, 7500πmm 2 ; C, 12500πmm 2 .

[0031] The area of ​​region B is 3 times that of region A, and the area of ​​region C is 5 times that of region B. Regions A, B, and C of different sizes require different amounts of photoresist. In other words, a large amount of photoresist is required in the initial stage of spraying photoresist, and only a small amount of photoresist is needed afterwards.

[0032] In order to achieve the purpose of spraying a corresponding amount of photoresist 50 onto the annular coating area, as shown in FIG. Figure 6 As shown, according to an embodiment of the present application, controlling the spraying rate of the photoresist nozzle 20 to gradually increase specifically includes: controlling the spraying rate of the photoresist nozzle 20 to gradually increase according to a fixed increase rate a until the spraying rate of the photoresist nozzle 20 reaches a first preset value V1. The first preset value V1 is determined according to the area of ​​the area to be coated, the spraying thickness of the photoresist 50, and the fixed increase rate, and the specific value of the first preset value V1 is not elaborated in detail herein.

[0033] Controlling the spraying rate of the photoresist nozzle 20 to gradually decrease specifically includes: controlling the spraying rate of the photoresist nozzle 20 to gradually decrease according to a first fixed deceleration b; when the spraying rate of the photoresist nozzle 20 gradually decreases to a second preset value V2, controlling the spraying rate of the photoresist nozzle 20 to gradually decrease according to a second fixed deceleration c, and the absolute value of the second fixed deceleration c is greater than the absolute value of the first fixed deceleration b, so as to achieve that the spraying rate of the photoresist corresponds to the gradually decreasing annular coating area.

[0034] Furthermore, the time for spraying the photoresist 50 is controlled between 0.1 seconds and 5 seconds. By controlling the spraying time of the photoresist 50 between 0.1 seconds and 5 seconds, a good spraying effect can be achieved. Spraying the photoresist 50 too slowly will cause the initially sprayed photoresist 50 to solidify, and spraying the photoresist 50 too quickly will cause a large amount of photoresist 50 to accumulate in a local area.

[0035] The ratio between the maximum and minimum values ​​of the photoresist spraying rate is about 2 to 10 times. If the photoresist 50 spraying rate is too slow, the initially sprayed photoresist 50 will solidify. If the photoresist 50 spraying rate is too fast, a large amount of photoresist 50 will accumulate in a local area.

[0036] According to an embodiment of the present application, the photoresist coating method further includes: obtaining the area to be coated of the semiconductor wafer 10; generating the area to be coated as multiple annular areas around the center of the semiconductor wafer 10, and multiple radial dimensions of the multiple annular areas are the same; calculating multiple areas to be coated in the multiple annular areas, and determining a fixed increase in speed, a first fixed deceleration, a first preset value, a second preset value, and a second fixed deceleration according to the multiple areas to be coated. Further, the fixed increase in speed a, the first fixed deceleration b, the first preset value V1, the second preset value V2, and the second fixed deceleration c need to be determined according to the area of ​​the area to be coated on the semiconductor wafer 10 and the required thickness of the photoresist 50, and the specific values ​​are not elaborated in detail here.

[0037] According to an embodiment of the present application, the photoresist coating method includes: controlling the photoresist nozzle 20 to spray the photoresist according to a fixed increase rate, a first fixed deceleration rate, and a second fixed deceleration rate by adjusting the spray pressure of the photoresist nozzle 20. The spray pressure varies with the viscosity of the photoresist, that is, while setting the spray pressure of the photoresist nozzle 20 according to the concentration of the photoresist, the spray rate of the photoresist can also be set according to the spray pressure of the photoresist nozzle 20.

[0038] According to an embodiment of the present application, the photoresist coating method includes: adjusting a fixed speed increase, a first fixed speed decrease, and a second fixed speed decrease according to the photoresist thickness required for the area to be coated. Further, according to the area of ​​the area to be coated on the semiconductor wafer 10 and the required thickness of the photoresist 50, the spraying amount of the photoresist 50 is controlled to be between 0.1g and 10g according to the thickness change.

[0039] It should be noted that the photoresist coating method of the embodiment of the present application can be applied to semiconductor devices, displays, memories, processors and semiconductor equipment.

[0040] The embodiments of the present disclosure are described above. However, these embodiments are only for the purpose of illustration and are not intended to limit the scope of the present disclosure. In order to achieve the same purpose, those skilled in the art may also design methods that are not completely the same as the methods described above. The scope of the present disclosure is defined by the attached claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A photoresist coating method, characterized in that: The photoresist coating method comprises: Placing a semiconductor wafer on a loading platform so that the center of the semiconductor wafer is located directly below a photoresist nozzle; Controlling the loading platform to drive the semiconductor wafer to rotate, and controlling the photoresist nozzle to spray photoresist toward the center of the semiconductor wafer; The spraying rate of the photoresist nozzle is controlled to gradually increase, and when the spraying rate of the photoresist nozzle reaches a first preset value, the spraying rate of the photoresist nozzle is controlled to gradually decrease until the semiconductor wafer is completely sprayed.

2. The photoresist coating method according to claim 1, characterized in that: The step of controlling the spraying rate of the photoresist nozzle to gradually increase specifically includes: The spraying rate of the photoresist nozzle is controlled to gradually increase at a fixed increasing rate until the spraying rate of the photoresist nozzle reaches the first preset value.

3. The photoresist coating method according to claim 2, characterized in that: The step of controlling the spraying rate of the photoresist nozzle to gradually decrease specifically includes: Controlling the spraying rate of the photoresist nozzle to gradually decrease according to a first fixed deceleration rate; When the spraying rate of the photoresist nozzle gradually decreases to a second preset value, the spraying rate of the photoresist nozzle is controlled to gradually decrease according to a second fixed deceleration rate, An absolute value of the second fixed deceleration is greater than an absolute value of the first fixed deceleration.

4. The photoresist coating method according to claim 3, characterized in that: The photoresist coating method further comprises: Acquiring a region to be coated of the semiconductor wafer; Generating the area to be coated into a plurality of annular areas surrounding the center of the semiconductor wafer, wherein the plurality of annular areas have the same radial dimensions; A plurality of areas to be coated of the plurality of annular regions are calculated, and the fixed speed increase, the first fixed speed reduction, the first preset value, the second preset value and the second fixed speed reduction are determined according to the plurality of areas to be coated.

5. The photoresist coating method according to claim 3, characterized in that: The photoresist coating method comprises: By adjusting the spraying pressure of the photoresist nozzle, the photoresist nozzle is controlled to spray photoresist according to the fixed speed increase, the first fixed speed decrease and the second fixed speed decrease.

6. The photoresist coating method according to claim 4, characterized in that: The photoresist coating method comprises: The fixed speed increase, the first fixed speed decrease, the first preset value, the second preset value and the second fixed speed decrease are adjusted according to the photoresist thickness required for the plurality of annular regions.

7. The photoresist coating method according to claim 1, characterized in that: The spraying time of the photoresist is controlled between 0.1 seconds and 5 seconds.

8. The photoresist coating method according to claim 1, characterized in that: The ratio of the maximum value to the minimum value of the spraying rate of the photoresist is controlled to be between 2 times and 10 times.

9. The photoresist coating method according to claim 1, characterized in that: According to the area of ​​the to-be-coated region on the semiconductor wafer and the required thickness of the photoresist, the spraying amount of the photoresist is controlled to be between 0.1 g and 10 g.

10. The photoresist coating method according to any one of claims 1 to 9, characterized in that: The rotation speed of the loading platform is adjusted and the injection pressure of the photoresist nozzle is set according to the concentration of the photoresist, so that the photoresist is gradually thrown from the outside to the inside to the area to be coated on the semiconductor wafer under the centrifugal force of the semiconductor wafer.

Images