Photomask and critical dimension control method thereof

Abstract

The invention provides a photomask and a critical dimension control method thereof, and belongs to the field of semiconductors. The key size control method of the photomask comprises the following steps: providing the photomask; and spin-coating photoresist on the surface of the photomask. And baking, exposing and developing the photoresist in the first region in sequence to expose the first region. And cleaning the exposed first region for a set time by using a cleaning solution with a set flow rate, and correcting the graph of which the line width is greater than a set value, so that the line width of the graph of the first region is within a design threshold value. According to the invention, the first region is exposed; and cleaning the exposed first area for a set time by using a cleaning solution with a set flow, and correcting the graph of which the line width is greater than a set value. According to the invention, when the abnormal pattern on the photomask plate is corrected, the influence on the normal pattern meeting the standard design can be avoided, the production yield of the photomask plate can be improved, the scrap risk can be reduced, and the production cost can be saved.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, and in particular to a photomask and a key dimension control method thereof. Background Art

[0002] A photomask is a structure that is used to make various functional patterns on a film, plastic or glass substrate and precisely position them for selective exposure of a photoresist coating. Photomasks are widely used and are required in all fields involving photolithography.

[0003] After the photomask has gone through various processes, the pattern for photolithography is set on the surface of the photomask, and the line width of the pattern is fixed accordingly. If the average value of the line width deviates too much from the design value (MTT), it does not meet the photomask design specifications.

[0004] In the prior art, in order to solve the above technical problems, the photomask is cleaned as a whole by using a cleaning method. Although this method can correct the graphics with line width larger than the design, so that the line width is reduced and the MTT value is brought back to the design specification, the prior art, however, is to clean the entire photomask, which will cause the graphics on the photomask whose line width meets the design specification to also be cleaned, so that the line width of such graphics is lower than the design specification value, deviating from the normal MTT value.

[0005] It should be noted that the information disclosed in the background technology section of the invention is only intended to deepen the understanding of the general background technology of the invention, and should not be regarded as an admission or suggestion in any form that the information constitutes prior art already known to those skilled in the art. Summary of the invention

[0006] The object of the present invention is to provide a photomask and a critical dimension control method thereof, so as to solve the problem that the line width of the pattern of the photomask does not meet the design specification.

[0007] In order to solve the above technical problems, the present invention provides a method for controlling the critical dimension of a photomask, comprising:

[0008] A photomask is provided, wherein the photomask has a pattern for etching, wherein the pattern has a line width that meets the design, and an area on the photomask where the line width of the pattern is greater than a design threshold is defined as a first area, and an area on the photomask where the line width of the pattern is within the design threshold is defined as a second area;

[0009] Spin coating photoresist on the surface of the photomask;

[0010] sequentially baking, exposing and developing the photoresist in the first area to expose the first area;

[0011] The exposed first area is cleaned with a cleaning liquid of a set flow rate for a set time, and the graphics with a line width greater than a set value are corrected so that the line width of the graphics in the first area is within a design threshold.

[0012] Preferably, when the photoresist is spin-coated on the surface of the photomask, the rotation speed of the coating machine is 1-1000 r / min, and the spraying amount is 1-10 ml.

[0013] Preferably, when the photoresist in the first region is baked, the baking temperature is 50-90° C. and the baking time is 10 min-60 min.

[0014] Preferably, when the photoresist in the first region is exposed, the exposure dose is 2-10 uc / cm 2 The post-exposure baking temperature is 25-80°C, and the post-exposure baking time is 10min-30min.

[0015] Preferably, when developing the photoresist in the first area, the rotation speed of the developing machine is 1-1000 r / min, the developing time is 1 min-10 min, and the pure water flushing time is 10 min-30 min.

[0016] Preferably, when cleaning the exposed first area, the cleaning liquid used is SC1, and the SC1 includes a mixture of ammonia water, hydrogen peroxide, and water, and the volume ratio of the ammonia water, hydrogen peroxide, and water is: 0.5-0.3:0.5:99.

[0017] Preferably, when cleaning the exposed first area, the cleaning solution used is TC1, and the concentration of TC1 is 2.38%.

[0018] Preferably, when cleaning the exposed first area, the cleaning liquid used is a mixture of SC1 and TC1, wherein the concentration of TC1 is 2.38%, the volume ratio of ammonia water, hydrogen peroxide, and water in SC1 is: 0.5-0.3:0.5:99, and the volume ratio of TC1 to SC1 is 1:4.

[0019] Preferably, the rotation speed of the cleaning machine is 1-1200 r / min, the flow rate of the cleaning liquid is 0.1-2 L / min, and the flushing time of the cleaning liquid is 1 min-5 min.

[0020] Preferably, after cleaning the first area, the method further comprises:

[0021] Rinse the photomask with water at a set temperature, including:

[0022] Rinse the photomask with water at a temperature of 60-80°C for 1 min-4 min;

[0023] Next, the photomask is rinsed with water at a temperature of 22-25° C. for 2 min to 6 min.

[0024] Based on the same inventive concept, the present invention also provides a photomask, including using the above-mentioned photomask critical dimension control method to correct the pattern line width of the photomask.

[0025] Compared with the prior art, the critical dimension control method of the photomask of the present invention has the following advantages:

[0026] The present invention spin-coats photoresist on the surface of the photomask; sequentially bakes, exposes and develops the photoresist in the first area to expose the first area; washes the exposed first area with a cleaning liquid of a set flow rate for a set time, and corrects the graphics with a line width greater than a set value. While correcting the abnormal graphics on the photomask, it can also avoid affecting the normal graphics that meet the standard design, thereby improving the production yield of the photomask, reducing the risk of scrapping, and saving production costs.

[0027] The photomask provided by the present invention and the critical dimension control method of the photomask provided by the present invention belong to the same inventive concept. Therefore, the photomask provided by the present invention has at least all the advantages of the critical dimension control method of the photomask provided by the present invention, and can improve the production yield of the photomask, reduce the risk of scrapping, and save production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a flow chart of a critical dimension control method of a photomask in one embodiment of the present invention;

[0029] Figure 2 It is a flow chart of a critical dimension control method of a photomask provided by the present invention in one embodiment of the present invention, and a schematic diagram of the structure of the photomask obtained;

[0030] In the figure,

[0031] 100-photomask; 110-first area;

[0032] 120-second area; 200-photoresist. DETAILED DESCRIPTION

[0033] In order to make the purpose, advantages and features of the present invention clearer, the photomask and the critical dimension control method thereof proposed by the present invention are further described in detail in combination with the accompanying drawings and specific embodiments. It should be noted that the accompanying drawings are in a very simplified form and are not in exact proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. It should be understood that the drawings in the specification do not necessarily show the specific structure of the present invention in proportion, and the illustrative features used to illustrate certain principles of the present invention in the drawings in the specification will also be slightly simplified. The specific design features of the present invention disclosed herein include, for example, specific dimensions, directions, positions and shapes, which will be determined in part by the specific application and use environment. In addition, in the embodiments described below, the same figure mark is sometimes used in common between different drawings to represent the same part or the part with the same function, and its repeated description is omitted. In this specification, similar numbers and letters are used to represent similar items, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0034] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0035] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0036] The core idea of ​​the present invention is to provide a critical dimension control method for a photomask, which can perform targeted processing on patterns with abnormal MTT values ​​in the photomask, and at the same time, can avoid protecting patterns with normal MTT values ​​in the photomask and avoid affecting patterns with normal MTT values.

[0037] In order to realize the above idea, the present invention provides a method for controlling the critical dimension of a photomask. Figure 1 and Figure 2A specific implementation of a method for controlling a critical dimension of a photomask is disclosed. The method for controlling a critical dimension of a photomask includes the following steps S1 to S4.

[0038] Step S1: Provide a photomask 100, wherein the photomask 100 has a pattern for etching, and the pattern has a line width that meets the design, and define an area on the photomask 100 where the line width of the pattern is greater than a design threshold as a first area 110, and define an area on the photomask 100 where the line width of the pattern is within the design threshold as a second area 120.

[0039] Specifically, refer to Figure 1 and Figure 2 As shown, the photomask 100 has graphics of various line widths for subsequent etching processes. The line width of the graphics must meet the designed MTT value in order to meet the process requirements. The area on the photomask 100 where the line width is greater than the design threshold is defined as the first area 110, and the area on the photomask 100 where the line width is within the design threshold is defined as the second area 120. The design threshold for the MTT value can be a certain value or a threshold that limits a certain range. The photomask 100 shown in Figure (2a) will be used as an example for explanation. In Figure (2a), the upper half of the photomask 100 is defined as the first area 110, and the MTT value of the upper half is 2 nanometers (nm) higher than the design value. The MTT value of the lower half of the photomask 100 is within the normal range, which is used as an example of the second area 120. It should be noted that the graphics at any position of the photomask 100 may be higher than the design value. The upper and lower half positions of the photomask 100 are explained as just one example.

[0040] Step S2: Spin-coating the photoresist 200 on the surface of the photomask 100 .

[0041] Specifically, refer to Figure 1 and Figure 2 As shown, the photomask 100 is fed into a glue coater, and the photoresist 200 is spin-coated on the entire surface of the photomask 100. When the photoresist 200 is spin-coated on the surface of the photomask 100, the rotation speed of the glue coater is 1-1000r / min, and the spraying amount is 1-10ml. The rotation speed of the glue coater can be 1r / min, 500r / min, 1000r / min, or any rotation speed in the range of 1-1000r / min. For a photomask 100 with a standard size of 6 inches, the spraying amount of the photoresist 200 can be 1ml, 5ml, 10ml, or any value from 1-10ml. The spraying amount of the photoresist 200 can be changed according to the size of the photomask 100, as long as the first area 110 and the second area 120 of the photomask 100 can be completely covered. That is, a structure as shown in Figure (2b) is formed.

[0042] Step S3 : performing baking, exposure and development treatments on the photoresist 200 in the first region 110 in sequence to expose the first region 110 .

[0043] Specifically, refer to Figure 1 As shown, the first area 110 is exposed, and the second area 120 is not exposed, forming a structure as shown in Figure (2c). When the photoresist 200 of the first area 110 is baked in sequence, the baking temperature is 50-90°C and the baking time is 10min-60min. When the photoresist 200 of the first area 110 is exposed, the exposure dose is 2-10uc / cm 2 , the post-exposure baking temperature is 25-80°C, and the post-exposure baking time is 10min-30min. When developing the photoresist 200 of the first area 110, the developing machine speed is 1-1000r / min, the developing time is 1min-10min, and the pure water flushing time is 10min-30min. After development, the first area 110 is exposed to form a structure as shown in Figure (2d). While the first area 110 is exposed, the second area 120 is not exposed.

[0044] It should be noted that Figure 2 The photomask 100 whose upper half is the first area 110 and whose lower half is the second area 120 can be measured by the CD-SEM machine to determine the MTT values ​​of different areas by measuring the line width data of the entire photomask 100. Line width (CD) measurement is also one of the manufacturing processes of the photomask 100. Each photomask will be measured by CD during the manufacturing process. The CD-SEM machine can give the coordinate position of the area that does not meet the MTT value setting specification, and the exposure machine can locate the area and expose the area.

[0045] Step S4: The exposed first region 110 is cleaned with a cleaning solution of a set flow rate for a set time, and the pattern with a line width greater than a set value is corrected so that the line width of the pattern in the first region 110 is within the design threshold.

[0046] Specifically, refer to Figure 1As shown, when cleaning the exposed first area 110, the cleaning liquid used may be SC1, which includes a mixture of ammonia water, hydrogen peroxide, and water, and the volume ratio of the ammonia water, hydrogen peroxide, and water is 0.5-0.3:0.5:99. When cleaning the exposed first area 110, the cleaning liquid TC1 may also be used, and the concentration of TC1 is 2.38%. Of course, the cleaning liquid may also be a mixture of SC1 and TC1. Among them, the concentration of TC1 is 2.38%, and the volume ratio of SC1 including ammonia water, hydrogen peroxide, and water is 0.5-0.3:0.5:99. And the volume ratio of TC1 to SC1 is 1:4, TC1 can micro-etch the photomask 100, and the H2O2 and NH4OH in SC1 can accelerate this process. The photomask 100 after the treatment in step S3 is placed in a cleaning machine with a cleaning liquid for cleaning. The photomask 100 is rinsed with a cleaning liquid. The rotation speed of the cleaning machine is 1-1200r / min, the flow rate of the cleaning liquid is 0.1-2L / min, and the cleaning liquid rinsing time is 1min-5min. The rotation speed of the cleaning machine can be 1r / min, 500r / min, 1200r / min, or any rotation speed in the range of 1-1200r / min. The flow rate of the cleaning liquid can be 0.1L / min, 1.0L / min, 2L / min, or any value in the range of 0.1-2L / min. The cleaning liquid rinsing time can be 1min, 3min, 5min, or any time in the range of 1min-5min. A structure as shown in Figure (2e) is formed. By using a cleaning liquid to clean the exposed first area 110, the pattern greater than the MTT value can be further etched, thereby reducing the line width of the pattern in the first area 110 and pulling the line width of the pattern back to the MTT value that meets the standard design. Since the pattern of the second region 120 is covered by the photoresist 200 , the pattern of the second region 120 can be protected, thereby preventing the line width of the pattern of the second region 120 from being reduced when the photomask 100 is cleaned with a cleaning solution.

[0047] After cleaning the first area 110, the method further includes:

[0048] The photomask 100 is rinsed with water at a set temperature, including: rinsing the photomask 100 with water at a temperature of 60-80°C for 1-4 minutes; then, rinsing the photomask 100 with water at a temperature of 22-25°C for 2-6 minutes. The photomask 100 is rinsed with water at different temperatures to remove the photoresist 200 covering the surface of the second region 120. That is, a structure as shown in FIG. (2f) is formed.

[0049] like Figure 2As shown, the upper half of the photomask 100 where the MTT value is higher than the standard by 2 nanometers (nm) is taken as the first region 110, and the lower half of the photomask 100 where the MTT value is within the normal range is taken as an example.

[0050] First, the photomask 100 is sent into a coating machine, and a rotation speed of 500 r / min and a spraying amount of 6 ml are selected to coat the photomask 100 with photoresist 200.

[0051] Next, the film is baked at 80°C for 40 minutes. Then, laser exposure is selected, and the process conditions may be Dose 4.8uc / cm 2 The photomask 100 is baked for the second time. The second baking temperature can be 70°C and the baking time can be 15 minutes. After the exposure and baking are completed, the photomask 100 can be sent for development. The development process conditions can be set to a rotation speed of 600r / min, a development time of 5 minutes, and a pure water rinse time of 8 minutes.

[0052] After the development is completed, the upper half area is exposed and the lower half area is covered by the photoresist 200. At this time, the MTT value of the upper half area pattern is adjusted by cleaning. The cleaning process conditions can be set to a rotation speed of 100r / min, a flow rate of SC1 or TC1 cleaning solution of 1.2L / min, and a shower time of 5min.

[0053] Finally, a hot water rinse at 65°C for 4 minutes and a cold water rinse at 23°C for 2 minutes are used to remove 200 of the photoresist in the lower half. After adjusting the MTT value using the cleaning process, the residual glue on the photomask can be removed.

[0054] After measuring the processed photomask, the MTT value in the upper half area decreased and returned to the standard design value, while the MTT value in the lower half area remained unchanged. The abnormality processing was completed.

[0055] In order to realize the above idea, the invention also discloses a photomask, which uses the photomask critical dimension control method as described above to correct the pattern line width of the photomask 100.

[0056] The photomask provided in this embodiment and the critical dimension control method of the photomask provided in this embodiment belong to the same inventive concept. Therefore, the photomask provided in this embodiment has at least all the advantages of the critical dimension control method of the photomask provided in this embodiment, and can improve the production yield of the photomask 100, reduce the risk of scrapping, and save production costs.

[0057] In summary, the above embodiments provide detailed descriptions of different configurations of photomasks and methods for controlling critical dimensions thereof. Of course, the above descriptions are only descriptions of preferred embodiments of the present invention, and are not limitations on the scope of the present invention. The present invention includes but is not limited to the configurations listed in the above embodiments. Those skilled in the art can draw inferences based on the contents of the above embodiments. Any changes and modifications made by those of ordinary skill in the field of the present invention based on the above disclosures shall fall within the scope of protection of the claims.

Claims

1. A method for controlling a critical dimension of a photomask, characterized in that: include: A photomask is provided, wherein the photomask has a pattern for etching, wherein the pattern has a line width that meets the design, and an area on the photomask where the line width of the pattern is greater than a design threshold is defined as a first area, and an area on the photomask where the line width of the pattern is within the design threshold is defined as a second area; Spin coating photoresist on the surface of the photomask; sequentially baking, exposing and developing the photoresist in the first area to expose the first area; The exposed first area is cleaned with a cleaning liquid of a set flow rate for a set time, and the graphics with a line width greater than a set value are corrected so that the line width of the graphics in the first area is within a design threshold.

2. The critical dimension control method of a photomask according to claim 1, characterized in that: When the photoresist is spin-coated on the surface of the photomask, the rotation speed of the coating machine is 1-1000r / min, and the spraying amount is 1-10ml.

3. The critical dimension control method of a photomask according to claim 1, characterized in that: When the photoresist in the first area is baked, the baking temperature is 50-90° C. and the baking time is 10 min-60 min.

4. The critical dimension control method of a photomask according to claim 1, characterized in that: When the photoresist in the first area is exposed, the exposure dose is 2-10uc / cm 2 The post-exposure baking temperature is 25-80°C, and the post-exposure baking time is 10min-30min.

5. The critical dimension control method of a photomask according to claim 1, characterized in that: When developing the photoresist in the first area, the rotation speed of the developing machine is 1-1000 r / min, the developing time is 1 min-10 min, and the pure water flushing time is 10 min-30 min.

6. The critical dimension control method of a photomask according to claim 1, characterized in that: When cleaning the exposed first area, the cleaning solution used is SC1, which includes a mixture of ammonia water, hydrogen peroxide, and water, and the volume ratio of the ammonia water, hydrogen peroxide, and water is 0.5-0.3:0.5:

99.

7. The critical dimension control method of a photomask according to claim 1, characterized in that: When cleaning the exposed first area, the cleaning solution used is TC1, and the concentration of TC1 is 2.38%.

8. The critical dimension control method of a photomask according to claim 7, characterized in that: When cleaning the exposed first area, the cleaning liquid used is a mixture of SC1 and TC1, wherein the concentration of TC1 is 2.38%, the volume ratio of ammonia water, hydrogen peroxide, and water in SC1 is: 0.5-0.3:0.5:99, and the volume ratio of TC1 to SC1 is 1:

4.

9. The critical dimension control method of a photomask according to claim 1, characterized in that: After cleaning the first area, the method further comprises: Rinse the photomask with water at a set temperature, including: Rinse the photomask with water at a temperature of 60-80°C for 1 min-4 min; Next, the photomask is rinsed with water at a temperature of 22-25° C. for 2 min to 6 min.

10. A photomask, characterized in that: include: The pattern line width of the photomask is corrected by using the photomask critical dimension control method as described in any one of claims 1 to 9.

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