Exposure dose compensation method and system for critical size during mask exposure

Abstract

The invention discloses an exposure dose compensation method and system for a critical dimension during mask exposure. The method comprises the following steps: designing a plurality of test patterns according to key pattern factors influencing the mask exposure; manufacturing the plurality of test patterns into a mask plate; measuring differences between the measured values and the design values of the key shapes of the various masks, and summarizing and summarizing a relational graph between the measured values and the design values of different sizes of the key shapes under different exposure doses; according to the measurement result, obtaining the relationship between different design sizes and the exposure dose correction amount under various key shapes, and incorporating the relationship into a control system; the method comprises the following steps: before production of a mask, identifying the characteristics of key shapes of the mask, and inputting the characteristics into a control system; according to the exposure dose compensation method for the critical dimension during mask exposure, the standard deviation between the measured value and the design value of the critical dimension in mask production can be reduced to half of the original standard deviation, the coincidence rate of the manufacturing process is greatly improved, and the scrapping condition of the mask is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of mask plates, and in particular to an exposure dose compensation method and system for a critical dimension during mask plate exposure. Background Art

[0002] Mask production includes processes such as exposure, development, etching, and stripping;

[0003] Exposure: Through the photolithography machine, the designed pattern is exposed on the blank mask coated with photoresist by scanning to produce a latent image. When exposing, it is necessary to set exposure parameters such as Dose.

[0004] Development: Use chemical liquid to remove the exposed (or unexposed, depending on the type of photoresist) photoresist to expose the chrome layer of the mask pattern.

[0005] Etching: Use chemical solution (wet method) or plasma jet (dry method) to remove the exposed chromium layer on the mask. The chromium covered by photoresist will remain on the mask.

[0006] Stripping: Remove all photoresist, leaving behind a mask with a chrome pattern on the quartz substrate.

[0007] The main factors affecting the difference between the measured and designed values ​​of the mask key shape are:

[0008] Blank mask characteristics: photoresist type, thickness, manufacturing process, etc.;

[0009] The larger the exposure dose, the more energy it has, and the size of the exposed part of the pattern will become larger accordingly;

[0010] The developing and etching process, also known as the post-processing process, includes the developer concentration, developing time, etching solution type, etching time, etc. The higher the concentration and the longer the time, the larger the size of the correspondingly removed part of the pattern will be;

[0011] Usually for a raw material, there is a pair of matching exposure doses and post-processing processes. When the material and equipment are stable, the same test pattern is repeatedly tested under this process condition, and the difference between the measured value and the designed value is relatively certain. However, when other conditions remain unchanged and only the design pattern is different, the difference between the measured value and the designed value of the key shape will also be significantly different.

[0012] The mask is affected by the graphics itself, and in actual mask production, the graphics of the masks are all different, which will lead to obvious differences between the key shape measurement values ​​and design values ​​of the mask.

[0013] The difference between the critical shape measurement value and the design value is one of the main indicators of the quality of the mask product. In other words, the above-mentioned problems seriously affect the quality of the mask. Summary of the invention

[0014] The technical problem to be solved by the present invention is to propose an exposure dose compensation method for the critical dimensions during mask exposure. This method reduces the standard deviation of the critical dimension measurement value and the design value in mask production to half of the original value, greatly improves the process compliance rate, and reduces the scrapping of masks.

[0015] In order to solve the above technical problems, the present invention provides an exposure dose compensation method for critical dimensions during mask exposure, comprising the following steps:

[0016] Design a variety of test patterns based on key pattern factors that affect mask exposure;

[0017] The plurality of test patterns are made into a mask;

[0018] Measuring the differences between the measured values ​​and the designed values ​​of the various mask key shapes, and summarizing the relationship between the measured values ​​and the designed values ​​of the various key shapes of different sizes at different exposure doses;

[0019] Based on the above measurement results, the relationship between different design dimensions and exposure dose correction under various key shapes is obtained and incorporated into the control system;

[0020] Before the mask is produced, the key shape features of the mask are identified and entered into the control system;

[0021] The control system automatically selects the corresponding relationship according to the input conditions, calculates the corresponding exposure dose correction amount, and obtains the exposure dose for each mask product according to the exposure dose correction amount.

[0022] Preferably, the “factors influencing the key graphics during mask exposure” include: the type of the key shape is a line, a seam, a circle, or a square; the design size of the key shape; and the graphic density of the key shape.

[0023] Preferably, the test pattern set includes key shapes of different sizes, key shapes of different pattern densities, and key shapes with alternating black and white effects.

[0024] Preferably, the control system is an ERP system.

[0025] Preferably, the “deriving the relationship between different design dimensions and exposure dose correction amounts under various key shapes” is specifically: fitting the relationship between different design dimensions and exposure dose correction amounts under various key shapes according to a fitting strategy to derive a fitting formula.

[0026] Preferably, the fitting strategy is specifically as follows: obtaining samples (xi ,y i ) where i = (1, 2, 3, ..., n), and the fitting function is:

[0027] h(x)=a0+a1*x 2 +a2*x 2 +a3*x 3

[0028] n groups of samples of n x i Substitute the values ​​into the fitting function to find a set of coefficients (a0, a1, a2, a3) such that ∑(h(x)-y i ) 2 The value of is the smallest, and then the coefficients (a0, a1, a2, a3) are substituted into the fitting function to obtain the fitting formula h(x) of the key shape.

[0029] Preferably, the corresponding mask is exposed by a photolithography machine according to the exposure dose of each mask product.

[0030] In order to solve the above problems, the present invention also discloses a compensation system using the exposure dose compensation method for critical dimensions during mask exposure described above; comprising a measurement module, an exposure dose compensation amount relationship summary setting module and a control system;

[0031] The measuring module is used to measure the difference between the measured values ​​and the designed values ​​of the key shapes of the various masks;

[0032] The exposure dose correction relationship summary setting module is used to summarize the relationship between different design dimensions and exposure dose correction amounts under various key shapes;

[0033] The control system is used to automatically select the corresponding relationship, calculate the corresponding exposure dose correction amount, and obtain the exposure dose for each mask product according to the exposure dose correction amount.

[0034] After adopting the above method, a variety of test patterns are designed according to the factors that affect the key patterns during mask exposure; the above test patterns are made into masks; the differences between the measured values ​​and the designed values ​​of the key shapes of the various masks are measured, and the relationship diagram between the measured values ​​and the designed values ​​of the different sizes of the various key shapes under different exposure doses is summarized; based on the above measurement results, the relationship between the different design dimensions and the exposure dose correction amount under various key shapes is obtained and incorporated into the control system; before the mask is produced, the characteristics of the key shape of the mask are identified and entered into the control system; the control system automatically selects the corresponding relationship according to the input conditions, calculates the corresponding exposure dose correction amount, and obtains the exposure dose for each mask product according to the exposure dose correction amount; the exposure dose compensation method used for the key dimensions during the exposure of the mask makes the standard deviation of the key dimension measurement value and the design value in the mask production can be reduced to half of the original, the process compliance rate is greatly improved, and the scrapping of the mask is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A flow chart of an exposure dose compensation method for a critical dimension during mask exposure of the present invention;

[0036] Figure 2 A system block diagram of an exposure dose compensation system for a critical dimension during mask exposure of the present invention;

[0037] Figure 3 A pattern for designing a plurality of test patterns according to the key pattern factors affecting the exposure of the mask plate in the present invention;

[0038] Figure 4 Another pattern of the present invention is to design multiple test patterns according to key pattern factors affecting the exposure of the mask;

[0039] Figure 5 Schematic diagram of the relationship between the measured values ​​and the designed values ​​of different sizes of various key shapes under different exposure doses of the present invention. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0041] Embodiment 1

[0042] See also Figure 1 , Figure 1 A flow chart of an exposure dose compensation method for a critical dimension during mask exposure of the present invention;

[0043] This embodiment discloses an exposure dose compensation method for a critical dimension during mask exposure, comprising the following steps:

[0044] Design a variety of test patterns based on key pattern factors that affect mask exposure, such as Figure 3 and Figure 4 As shown;

[0045] The plurality of test patterns are made into a mask;

[0046] The differences between the measured values ​​and the designed values ​​of the various mask key shapes are measured, and the relationship between the measured values ​​and the designed values ​​of the various key shapes of different sizes at different exposure doses is summarized, such as Figure 5 As shown;

[0047] Based on the above measurement results, the relationship between different design dimensions and exposure dose correction under various key shapes is obtained and incorporated into the control system;

[0048] Before the mask is produced, the key shape features of the mask are identified and entered into the control system;

[0049] The control system automatically selects the corresponding relationship according to the input conditions, calculates the corresponding exposure dose correction amount, and obtains the exposure dose for each mask product according to the exposure dose correction amount.

[0050] Embodiment 2

[0051] This embodiment is based on the first embodiment. In this embodiment, the “factors affecting the key pattern during mask exposure” include: the type of the key shape is a line or a seam or a circle or a square; the design size of the key shape; the pattern density of the key shape;

[0052] like Figure 3 and Figure 4 As shown, the test pattern collection includes key shapes of different sizes, key shapes of different pattern densities, and key shapes with alternating black and white effects.

[0053] Embodiment 3

[0054] This embodiment is based on the first embodiment. In this embodiment, the control system is an ERP system.

[0055] Embodiment 4

[0056] This embodiment is based on the first embodiment. In this embodiment, the "deriving the relationship between different design dimensions and exposure dose correction amounts under various key shapes" is specifically: fitting the relationship between different design dimensions and exposure dose correction amounts under various key shapes according to the fitting strategy to obtain a fitting formula.

[0057] The fitting strategy is specifically to obtain samples (x i ,y i ) Where i = (1, 2, 3, ..., n), fitting function: h(x) = a0 + a1*x 2 +a2*x 2 +a3*x 3

[0058] n groups of samples of n x i Substitute the values ​​into the fitting function to find a set of coefficients (a0, a1, a2, a3) such that ∑(h(x)-y i ) 2 The value of is the smallest, and then the coefficients (a0, a1, a2, a3) are substituted into the fitting function to obtain the fitting formula h(x) of the key shape.

[0059] Embodiment 5

[0060] This embodiment is based on the first embodiment. In this embodiment, the corresponding mask is exposed by a photolithography machine according to the exposure dose of each mask product.

[0061] Embodiment 6

[0062] See also Figure 2 , Figure 2 A system block diagram of an exposure dose compensation system for a critical dimension during mask exposure of the present invention;

[0063] This embodiment discloses a compensation system for a critical dimension exposure dose compensation method used when exposing a mask plate according to any one of the first to fifth embodiments; the system comprises a measurement module, an exposure dose compensation amount relationship summary setting module, and a control system;

[0064] The measuring module is used to measure the difference between the measured values ​​and the designed values ​​of the key shapes of the various masks;

[0065] The exposure dose correction relationship summary setting module is used to summarize the relationship between different design dimensions and exposure dose correction amounts under various key shapes;

[0066] The control system is used to automatically select the corresponding relationship, calculate the corresponding exposure dose correction amount, and obtain the exposure dose for each mask product according to the exposure dose correction amount.

[0067] This method reduces the standard deviation of key dimension measurement values ​​and design values ​​in mask production to half of the original value, greatly improves the process compliance rate, and reduces the scrapping of masks.

[0068] It should be understood that the above are only preferred embodiments of the present invention, and the patent scope of the present invention cannot be limited thereto. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for compensating exposure dose for critical dimensions during mask exposure, characterized in that: The following steps are involved: Design a variety of test patterns based on key pattern factors that affect mask exposure; The plurality of test patterns are made into a mask; Measuring the differences between the measured values ​​and the designed values ​​of the various mask key shapes, and summarizing the relationship between the measured values ​​and the designed values ​​of the various key shapes of different sizes at different exposure doses; Based on the above measurement results, the relationship between different design dimensions and exposure dose correction under various key shapes is obtained and incorporated into the control system; Before the mask is produced, the key shape features of the mask are identified and entered into the control system; The control system automatically selects the corresponding relationship according to the input conditions, calculates the corresponding exposure dose correction amount, and obtains the exposure dose for each mask product according to the exposure dose correction amount.

2. The exposure dose compensation method for critical dimensions during mask exposure according to claim 1, characterized in that: The “key graphic factors affecting mask exposure” include: the type of the key shape is a line or a seam or a circle or a square; the design size of the key shape; and the graphic density of the key shape.

3. The exposure dose compensation method for critical dimensions during mask exposure according to claim 1, characterized in that: The test pattern collection includes key shapes of different sizes, key shapes of different pattern densities, and key shapes with alternating black and white effects.

4. The exposure dose compensation method for critical dimensions during mask exposure according to claim 1, characterized in that: The control system is an ERP system.

5. The exposure dose compensation method for critical dimensions during mask exposure according to claim 1, characterized in that: The “deriving the relationship between different design dimensions and exposure dose correction amounts under various key shapes” specifically includes: fitting the relationship between different design dimensions and exposure dose correction amounts under various key shapes according to a fitting strategy to derive a fitting formula.

6. The exposure dose compensation method for critical dimensions during mask exposure according to claim 5, characterized in that: The fitting strategy is specifically to obtain samples (x i ,y i )in, i=(1,2,3,……,n), fitting function: h(x)=a0+a1*x 2 +a2*x 2 +a3*x 3 n groups of samples of n x i Substitute the values ​​into the fitting function to find a set of coefficients (a0, a1, a2, a3) such that ∑(h(x)-y i ) 2 The value of is the smallest, and then the coefficients (a0, a1, a2, a3) are substituted into the fitting function to obtain the fitting formula h(x) of the key shape.

7. The exposure dose compensation method for critical dimensions during mask exposure according to claim 1, characterized in that: The corresponding mask is exposed through a photolithography machine according to the exposure dose of each mask product.

8. A compensation system using the exposure dose compensation method for critical dimensions during mask exposure according to any one of claims 1 to 7; characterized in that: It includes a measurement module, an exposure dose correction amount relationship summary setting module and a control system; The measuring module is used to measure the difference between the measured values ​​and the designed values ​​of the key shapes of the various masks; The exposure dose correction relationship summary setting module is used to summarize the relationship between different design dimensions and exposure dose correction amounts under various key shapes; The control system is used to automatically select the corresponding relationship, calculate the corresponding exposure dose correction amount, and obtain the exposure dose for each mask product according to the exposure dose correction amount.

Images