Measurement method and pre-compensation method for photomask manufacturing error

Abstract

The invention provides a photomask manufacturing error measuring method and a pre-compensation method, and the pre-compensation method comprises the steps: 1, providing a manufactured photomask to be measured, and uniformly measuring a pattern on the photomask according to a square grid which is not greater than 1.0 mm * 1.0 mm, so as to obtain a critical dimension distribution diagram of the pattern of the photomask; step 2, calculating a difference value between an actual measurement value of the critical dimension and a layout design target value according to the critical dimension distribution diagram of the photomask graph, and obtaining a delta distribution diagram of the difference value of the actual measurement value and the layout design target value; step 3, averaging all delta values obtained in each square grid to obtain feature distribution of photomask manufacturing errors; and 4, according to the characteristic distribution of the photomask manufacturing error, pre-compensating the photomask manufacturing error by using an energy compensation value of a design pattern provided by optical proximity effect correction. The detection of the manufacturing quality of the photomask is effectively improved, and the CDU problem caused by the manufacturing error of the photomask is solved by pre-supplementing in advance.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a method for measuring and pre-compensating a mask manufacturing error. Background Art

[0002] The photolithography process in the wafer production process is inseparable from the mask, and the mask production process directly affects the photolithography process window and even the subsequent wafer yield. For the production of masks, the mask factory uses the MPC (mask process control) process to control the mask production process. The wafer factory measures multiple points on the mask and monitors the measurement values ​​to control the production quality of the mask.

[0003] However, wafer factories use unified standards for mask measurement control without strict hierarchical management, which will cause yield loss for certain lithography processes with smaller process windows due to problems with the mask manufacturing process. If the mask factory uses the wrong MPC file to make the mask and cannot be discovered through monitoring and measurement, once a large number of wafers use the wrong mask to manufacture chips, it will cause immeasurable losses. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide a measurement method and a pre-compensation method for mask manufacturing errors, so as to solve the problem that the prior art cannot effectively detect mask defects caused by partial mask manufacturing errors through monitoring and measurement.

[0005] To achieve the above-mentioned purpose and other related purposes, the present application provides a method for measuring mask manufacturing errors, comprising:

[0006] Step 1, providing a prepared photomask to be measured, and uniformly measuring the pattern on the photomask according to a square grid no larger than 1.0 mm*1.0 mm, to obtain a critical dimension distribution diagram of the photomask pattern;

[0007] Step 2, according to the critical dimension distribution diagram of the mask pattern, the difference between the actual measured value of the critical dimension and the layout design target value is calculated to obtain a delta distribution diagram of the difference between the two;

[0008] Step three, taking the average of all delta values ​​obtained in each square grid to obtain the characteristic distribution of the mask manufacturing error.

[0009] Preferably, the size of the square grid is not greater than the size of the grid corresponding to the highest compensation capability of the lithography machine.

[0010] Preferably, the critical dimension of the mask pattern includes a line width or an aperture of the pattern.

[0011] Preferably, the critical dimension measurement equipment of the mask pattern comprises a critical dimension scanning electron microscope.

[0012] The present application also provides a pre-compensation method for mask production errors, comprising:

[0013] Step 1, providing a prepared photomask to be measured, and uniformly measuring the pattern on the photomask according to a square grid no larger than 1.0 mm*1.0 mm, to obtain a critical dimension distribution diagram of the photomask pattern;

[0014] Step 2, according to the critical dimension distribution diagram of the mask pattern, the difference between the actual measured value of the critical dimension and the layout design target value is calculated to obtain a delta distribution diagram of the difference between the two;

[0015] Step 3, taking the average of all delta values ​​obtained in each square grid to obtain the characteristic distribution of the mask manufacturing error;

[0016] Step 4: Pre-compensate the mask manufacturing error based on the characteristic distribution of the mask manufacturing error using the energy compensation value of the design pattern provided by the optical proximity effect correction.

[0017] Preferably, the size of the square grid is not greater than the size of the grid corresponding to the highest compensation capability of the lithography machine.

[0018] Preferably, the computer software for executing step 4 includes ASML's commercial IMO software.

[0019] As described above, the measurement method and pre-compensation method of mask manufacturing errors provided in the present application have the following beneficial effects: effectively improving the detection of mask manufacturing quality, and being able to solve the critical dimension uniformity (CDU) problem caused by mask manufacturing errors by pre-compensation in advance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 A flow chart showing a method for measuring a mask manufacturing error provided by an embodiment of the present application;

[0022] Figure 2 A flowchart showing a method for pre-compensating a mask manufacturing error provided by an embodiment of the present application;

[0023] Figure 3Shown is a schematic diagram of a square grid used to measure reticle patterns. DETAILED DESCRIPTION

[0024] The following describes the implementation of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0025] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating directions or positional relationships, are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0027] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0028] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0029] When measuring the mask, it is more necessary to measure the patterns with smaller process windows than to measure the CDU patterns to observe the uniformity of the entire mask, which is more conducive to detecting the quality of mask production. However, these hot spot patterns cannot be evenly distributed on the mask, and cannot monitor the uniformity of mask production. The most distributed patterns on the mask are circuit patterns, which are not uniform and have ever-changing target values, but these patterns are the failure patterns of the actual circuit.

[0030] In order to solve this problem, the present application provides a method for measuring and pre-compensating a mask manufacturing error.

[0031] See also Figure 1 , which shows a flow chart of a method for measuring mask manufacturing errors provided in an embodiment of the present application.

[0032] like Figure 1 As shown, the method for measuring the error of mask manufacturing includes the following steps:

[0033] Step 1, providing a prepared photomask to be measured, and uniformly measuring the pattern on the photomask according to a square grid no larger than 1.0 mm*1.0 mm, to obtain a critical dimension distribution diagram of the photomask pattern;

[0034] Step 2, according to the critical dimension distribution diagram of the mask pattern, the difference between the actual measured value of the critical dimension and the layout design target value is calculated to obtain a delta distribution diagram of the difference between the two;

[0035] Step 3: Take the average of all delta values ​​obtained in each square grid to obtain the characteristic distribution of mask manufacturing error.

[0036] In step 1, the size of the square grid used to uniformly measure the mask pattern cannot be larger than the size of the grid corresponding to the highest compensation capability of the lithography machine. The size of the grid corresponding to the highest compensation capability of the ASML machine is 1.0mm*1.0mm, and the size of the square grid used to uniformly measure the mask pattern can be 0.2mm*0.2mm.

[0037] As an example, the critical dimension of the mask pattern includes the line width, aperture, etc. of the pattern, and the critical dimension measurement equipment of the mask pattern includes a critical dimension scanning electron microscope (CD-SEM).

[0038] In step 2, the delta distribution diagram can be used to determine which mask graphics have a difference between the actual measured value of the critical dimension and the target value of the layout design that is not within the normal distribution range. These mask graphics are abnormal graphics. Due to the influence of measurement errors and pattern design errors, the difference between the actual measured value and the target value of the critical dimension of the mask graphics may also be outside the normal distribution range. Therefore, it is necessary to eliminate the influence of measurement errors and pattern design errors to effectively determine whether the difference between the actual measured value and the target value of the critical dimension of the mask graphics is not within the normal distribution range due to mask manufacturing errors.

[0039] In step 3, by taking the average of all delta values ​​obtained in each square grid, the noise caused by pattern design and measurement errors can be reduced. Measurement errors (such as errors caused by energy jitter during exposure) and pattern design errors are both positive and negative. By taking the average, this part of the noise will be eliminated, and the critical dimension error of the mask pattern caused by the mask production process can be better reflected.

[0040] like Figure 3 As shown, the thickness of each part of line 1 and line 3 is different, and line 2 is S-shaped and the line width of each part is obviously different, which causes the delta value of the difference between the actual measured value of the critical dimension of each part of the above-mentioned line and the layout design target value to have positive and negative values. By taking the average, the positive and negative values ​​can be offset to different degrees to more accurately present the critical dimension error of the mask pattern caused by the mask production process.

[0041] The quality of mask production can be more effectively detected by controlling the mean value and 3sigma value in the delta mean corresponding to the hotspot pattern. Hotspot patterns are specific patterns in the design layout that may cause manufacturing defects even if they have passed the design rules checking (DRC). The image distortion caused by the optical proximity effect (OPE) is the main cause of hotspot patterns. Through high-precision and complex modeling lithography simulation, the layout area with a narrow process window that is prone to defects or failures is defined as a hotspot pattern.

[0042] See also Figure 2 , which shows a flow chart of a method for pre-compensating a mask production error provided in an embodiment of the present application.

[0043] like Figure 2 As shown, the pre-compensation method for mask manufacturing error includes the following steps:

[0044] Step 1, providing a prepared photomask to be measured, and uniformly measuring the pattern on the photomask according to a square grid no larger than 1.0 mm*1.0 mm, to obtain a critical dimension distribution diagram of the photomask pattern;

[0045] Step 2, according to the critical dimension distribution diagram of the mask pattern, the difference between the actual measured value of the critical dimension and the layout design target value is calculated to obtain a delta distribution diagram of the difference between the two;

[0046] Step 3, taking the average of all delta values ​​obtained in each square grid to obtain the characteristic distribution of the mask manufacturing error;

[0047] Step 4: Pre-compensate the mask manufacturing error based on the characteristic distribution of the mask manufacturing error using the energy compensation value of the design pattern provided by the optical proximity effect correction.

[0048] In step 1, the size of the square grid used to uniformly measure the mask pattern cannot be larger than the size of the grid corresponding to the highest compensation capability of the lithography machine. The size of the grid corresponding to the highest compensation capability of the ASML machine is 1.0mm*1.0mm, and the size of the square grid used to uniformly measure the mask pattern can be 0.2mm*0.2mm.

[0049] As an example, the critical dimension of the mask pattern includes the line width, aperture, etc. of the pattern, and the critical dimension measurement equipment of the mask pattern includes a critical dimension scanning electron microscope (CD-SEM).

[0050] In step 2, the delta distribution diagram can be used to determine which mask patterns have a critical dimension whose difference between the actual measured value and the target value that is not within the normal distribution range. These mask patterns are abnormal patterns. Due to the influence of measurement errors and pattern design errors, the difference between the actual measured value and the target value of the critical dimension of the mask pattern may also be outside the normal distribution range. Therefore, it is necessary to eliminate the influence of measurement errors and pattern design errors to effectively determine whether the difference between the actual measured value and the target value of the critical dimension of the mask pattern is not within the normal distribution range due to mask manufacturing errors.

[0051] In step 3, by taking the average of all delta values ​​obtained in each square grid, the noise caused by pattern design and measurement errors can be reduced. Measurement errors (such as errors caused by energy jitter during exposure) and pattern design errors are both positive and negative. By taking the average, this part of the noise will be eliminated, and the critical dimension error of the mask pattern caused by the mask production process can be better reflected.

[0052] like Figure 3As shown, the thickness of each part of line 1 and line 3 is different, and line 2 is S-shaped and the line width of each part is obviously different, which causes the delta value of the difference between the actual measured value of the critical dimension of each part of the above-mentioned line and the layout design target value to have positive and negative values. By taking the average, the positive and negative values ​​can be offset to different degrees to more accurately present the critical dimension error of the mask pattern caused by the mask production process.

[0053] The quality of mask production can be more effectively detected by controlling the mean value and 3sigma value in the delta mean corresponding to the hotspot pattern. Hotspot patterns are specific patterns in the design layout that may cause manufacturing defects even if they have passed the design rules checking (DRC). The image distortion caused by the optical proximity effect (OPE) is the main cause of hotspot patterns. Through high-precision and complex modeling lithography simulation, the layout area with a narrow process window that is prone to defects or failures is defined as a hotspot pattern.

[0054] In step 4, the computer software pre-compensates the mask manufacturing error by calling the energy compensation value of the corresponding design pattern provided by the optical proximity correction (OPC) according to the characteristic distribution of the mask manufacturing error. As an example, the computer software includes the commercial IMO software of ASML.

[0055] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present application in a schematic manner. Therefore, the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0056] In summary, the measurement method and pre-compensation method of mask manufacturing errors provided by this application can effectively improve the wafer factory's detection of mask manufacturing quality, and can solve the CDU problem caused by mask manufacturing errors by pre-compensation in advance. Therefore, this application effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0057] The above embodiments are merely illustrative of the principles and effects of the present application and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed by the present invention shall still be covered by the claims of the present application.

Claims

1. A method for measuring mask production errors, characterized in that: The method comprises: Step 1, providing a prepared photomask to be measured, and uniformly measuring the pattern on the photomask according to a square grid no larger than 1.0 mm*1.0 mm, to obtain a critical dimension distribution diagram of the photomask pattern; Step 2, according to the critical dimension distribution diagram of the mask pattern, calculating the difference between the actual measured value of the critical dimension and the layout design target value, and obtaining a delta distribution diagram of the difference between the two; Step three, taking an average of all delta values ​​obtained in each of the square grids to obtain a characteristic distribution of mask manufacturing errors.

2. The method according to claim 1, characterized in that The size of the square grid is not greater than the size of the grid corresponding to the highest compensation capability of the lithography machine.

3. The method according to claim 1, characterized in that The critical dimension of the mask pattern includes the line width or aperture of the pattern.

4. The method according to claim 1, characterized in that: The critical dimension measurement equipment of the mask pattern includes a critical dimension scanning electron microscope.

5. A method for pre-compensation of mask production error, characterized in that: The method comprises: Step 1: Provide the prepared photomask to be measured, and evenly measure the pattern on the photomask according to a square grid no larger than 1.0mm*1.0mm to obtain the critical dimension distribution diagram of the photomask pattern; Layout design Step 2, according to the critical dimension distribution diagram of the mask pattern, calculating the difference between the actual measured value of the critical dimension and the layout design target value, and obtaining a delta distribution diagram of the difference between the two; Step 3, taking an average of all delta values ​​obtained in each of the square grids to obtain a characteristic distribution of mask manufacturing errors; Step 4: pre-compensate the mask manufacturing error according to the characteristic distribution of the mask manufacturing error by using the energy compensation value of the design pattern provided by the optical proximity effect correction.

6. The method according to claim 5, characterized in that The size of the square grid is not greater than the size of the grid corresponding to the highest compensation capability of the lithography machine.

7. The method according to claim 5, characterized in that The computer software for executing step 4 includes ASML's commercial IMO software.

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