Method for monitoring factory return cleaning abnormity of photomask and phase shift mask layout

Abstract

The invention provides a method for monitoring factory return cleaning abnormity of a photomask and a phase shift mask layout, in the method for monitoring factory return cleaning abnormity of the photomask, a group of BIM (binary intensity mask) patterns and a group of PSM (phase shift mask) patterns are designed on a phase shift mask by utilizing the difference of cleaning strength of materials of a binary intensity mask (BIM) pattern and a phase shift mask (PSM) pattern; taking a cleaning-resistant BIM graph as a reference graph, after returning to a factory for cleaning, exposing the inspection wafer by using the cleaned phase shift mask, and respectively transferring the BIM graph and the PSM graph to the inspection wafer to obtain a second reference graph and a second process graph, and finally, determining whether the factory return cleaning of the photomask is abnormal or not by judging whether the deviation of the critical dimensions of the second reference pattern and the second process pattern is in a preset deviation interval or not. The monitoring method provided by the invention can accurately monitor whether the cleaning of the phase shift photomask is abnormal or not; and the influence of subsequent exposure of the phase shift photomask on the wafer is also actually considered.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor manufacturing, in particular to a method for monitoring abnormality of photomask factory cleaning and a phase shift mask layout. BACKGROUND

[0002] In the process of semiconductor manufacturing, photolithography transfers patterns onto wafers by using photomasks as intermediates, so the quality of photomask manufacturing is closely related to the quality of the pattern transfer process. Photomasks may be contaminated on the production line, so the contaminated photomasks are often returned to photomask manufacturers or professional semiconductor cleaning service providers for cleaning (referred to as factory cleaning).

[0003] The material of a PSM (Phase Shift Mask) photomask usually includes a special phase shift material layer (such as a molybdenum silicon compound). The special phase shift material layer is more sensitive to the cleaning process, so the PSM photomask is prone to over-cleaning during factory cleaning, which causes partial light transmission abnormality of the phase shift material layer (molybdenum silicon compound). Further, the current method for monitoring whether over-cleaning (abnormality of cleaning) occurs in the factory cleaning of the PSM photomask is to detect the light transmission rate and / or phase shift of the PSM photomask returned from the factory cleaning. This traditional monitoring method is not accurate enough, and does not actually consider the impact of the PSM photomask on the wafer during subsequent exposure. The main performance is that the pattern topography transferred from the PSM photomask to the wafer after processes such as exposure and development deviates too much. SUMMARY

[0004] The present application provides a method for monitoring abnormality of photomask factory cleaning and a phase shift mask layout, which can solve the problem that the traditional method for monitoring abnormality of photomask factory cleaning is not accurate enough and does not actually consider the impact of the PSM photomask on the wafer during subsequent exposure.

[0005] In one aspect, the present application provides a method for monitoring abnormality of photomask factory cleaning, comprising:

[0006] designing a set of binary intensity mask patterns and a set of phase shift mask patterns located on the side of the binary intensity mask patterns on a phase shift mask;

[0007] using the phase shift mask, performing at least one exposure on a production line wafer, in each photolithography process, transferring the binary intensity mask patterns to the production line wafer to obtain a first reference pattern, and transferring the phase shift mask patterns to the production line wafer to obtain a first process pattern;

[0008] measuring the critical dimensions of the first reference pattern and the critical dimensions of the first process pattern in each photolithography process, and obtaining the deviation of the critical dimensions of the first reference pattern and the critical dimensions of the first process pattern;

[0009] monitoring the deviation of the critical dimension of the first reference pattern and the critical dimension of the first process pattern in each lithography process, and ensuring that the deviation of the critical dimension of the first reference pattern and the critical dimension of the first process pattern is in a preset deviation range;

[0010] after the phase shift mask return cleaning, using the phase shift mask to perform one-time exposure on a test wafer to transfer the binary intensity mask pattern to the test wafer to obtain a second reference pattern, and transfer the phase shift mask pattern to the test wafer to obtain a second process pattern;

[0011] measuring the critical dimension of the second reference pattern and the critical dimension of the second process pattern, and obtaining the deviation of the critical dimension of the second reference pattern and the critical dimension of the second process pattern;

[0012] determining whether the deviation of the critical dimension of the second reference pattern and the critical dimension of the second process pattern is in the preset deviation range, if the deviation of the critical dimension of the second reference pattern and the critical dimension of the second process pattern is in the preset deviation range, it is determined that the mask return cleaning is normal; if the deviation of the critical dimension of the second reference pattern and the critical dimension of the second process pattern is not in the preset deviation range, it is determined that the mask return cleaning is abnormal.

[0013] Optionally, in the method for monitoring abnormal mask return cleaning, the preset deviation range is [-3nm, 3nm].

[0014] Optionally, in the method for monitoring abnormal mask return cleaning, the critical dimension of the first reference pattern at least includes the line width of the straight line in the first reference pattern, the distance between the straight lines in the first reference pattern; the critical dimension of the first process pattern at least includes the line width of the straight line in the first process pattern, the distance between the straight lines in the first process pattern.

[0015] Optionally, in the method for monitoring abnormal mask return cleaning, the critical dimension of the second reference pattern at least includes the line width of the straight line in the second reference pattern, the distance between the straight lines in the second reference pattern; the critical dimension of the second process pattern at least includes the line width of the straight line in the second process pattern, the distance between the straight lines in the second process pattern.

[0016] Optionally, in the method for monitoring abnormal mask return cleaning, the phase shift mask includes a base plate, a phase shift film layer and a light shielding film layer, the phase shift film layer is located on the base plate, and the light shielding film layer is located on the phase shift film layer.

[0017] Optionally, in the method for monitoring abnormality of photomask factory cleaning, the binary intensity mask pattern comprises a base plate, a first patterned phase shift film layer on the base plate, and a patterned light shielding film layer covering the first patterned phase shift film layer.

[0018] Optionally, in the method for monitoring abnormality of photomask factory cleaning, the phase shift mask pattern comprises a base plate and a second patterned phase shift film layer on the base plate.

[0019] Optionally, in the method for monitoring abnormality of photomask factory cleaning, the material of the phase shift film layer is silicon molybdate.

[0020] Optionally, in the method for monitoring abnormality of photomask factory cleaning, the material of the light shielding film layer is metal chromium.

[0021] Optionally, in the method for monitoring abnormality of photomask factory cleaning, the binary intensity mask pattern and the phase shift mask pattern are the same.

[0022] In another aspect, the embodiments of the present application also provide a phase shift mask plate layout used in the method for monitoring abnormality of photomask factory cleaning, comprising a base plate, a binary intensity mask pattern, and a phase shift mask pattern on the side of the binary intensity mask pattern, wherein the binary intensity mask pattern and the phase shift mask pattern are respectively arranged on the base plate.

[0023] The technical scheme of the present application has at least the following advantages:

[0024] The method for monitoring abnormal photomask return cleaning provided in this application utilizes the difference in cleaning resistance between binary intensity mask (BIM) patterns and phase shift mask (PSM) patterns. A set of BIM patterns and a set of PSM patterns are designed on the phase shift mask. Then, in routine photolithography, the BIM patterns and PSM patterns are transferred to the production line wafer to obtain a first reference pattern and a first process pattern. Using the cleaning-resistant BIM pattern (first reference pattern) as the reference pattern, the deviation of the critical dimensions of the first reference pattern and the first process pattern is monitored and ensured to fall within a preset deviation range. Next, after return cleaning, the phase shift mask is used to expose the inspection wafer, transferring the BIM pattern and PSM pattern to the inspection wafer to obtain a second reference pattern and a second process pattern. Finally, using the cleaning-resistant BIM pattern (second reference pattern) as the reference pattern, it is determined whether the deviation of the critical dimensions of the second reference pattern and the second process pattern is within the preset deviation range. If the deviation is not within the preset deviation range, the photomask return cleaning is determined to be abnormal (over-cleaning). The method for monitoring abnormalities during the return cleaning of photomasks provided in this application can effectively consider the impact of phase-shifting photomasks on wafers during subsequent exposure. It can efficiently and accurately monitor whether abnormalities occur during the cleaning of phase-shifting photomasks, thus avoiding the problem of excessive cleaning of phase-shifting photomasks during return cleaning, which would affect subsequent photolithography. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a flowchart of a method for monitoring abnormalities during photomask return cleaning according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the structure of the phase-shifting mask according to an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of the phase shift mask layout according to an embodiment of the present invention;

[0029] The reference numerals in the attached figures are explained as follows:

[0030] 11-Base plate, 12-Phase shift film, 13-Light-shielding film, 21-Binary intensity mask pattern, 22-Phase shift mask pattern. Detailed Implementation

[0031] With reference to the drawings, the technical solutions in the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the scope of the present application.

[0032] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0033] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements, it can be wireless connection, or it can be wired connection. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0034] 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 there is no conflict between them.

[0035] The embodiment of the present application provides a method for monitoring abnormality of cleaning of a photomask returned to a factory, referring to Figure 1 , Figure 1 is a flowchart of the method for monitoring abnormality of cleaning of a photomask returned to a factory of the embodiment of the present application, and the method for monitoring abnormality of cleaning of a photomask returned to a factory comprises the following steps.

[0036] Firstly, step S1 is performed: referring to Figure 2 and Figure 3 , Figure 2 is a structural schematic diagram of a phase shift mask plate of the embodiment of the present application, Figure 3 is a structural schematic diagram of a layout of a phase shift mask plate of the embodiment of the present application, a set of binary intensity mask patterns (BIM patterns) 21 and a set of phase shift mask patterns (PSM patterns) 22 located on the side of the binary intensity mask patterns 21 are designed on the phase shift mask plate.

[0037] Preferably, as Figure 2As shown, the phase shift mask plate comprises a base plate 11, a phase shift film layer 12 and a light shielding film layer 13, the phase shift film layer 12 is located on the base plate 11, and the light shielding film layer 13 is located on the phase shift film layer 12.

[0038] In this embodiment, the material of the base plate 11 is quartz glass.

[0039] The binary intensity mask pattern 21 comprises a first patterned phase shift film layer on the base plate 11 and a patterned light shielding film layer covering the first patterned phase shift film layer.

[0040] Preferably, the material of the phase shift film layer 12 is molybdenum silicon compound, and the material of the light shielding film layer 13 is metal chromium. It is worth noting that since the material of the light shielding film layer 13 is metal chromium, it is less likely to be damaged by excessive cleaning during factory cleaning, so the BIM pattern 21 is basically not affected by factory cleaning, thereby serving as a reference pattern for the PSM pattern 22.

[0041] Further, the phase shift mask pattern 22 comprises a second patterned phase shift film layer on the base plate 11.

[0042] In this embodiment, the binary intensity mask pattern 21 and the phase shift mask pattern 22 are the same.

[0043] Then, step S2 is performed: using the phase shift mask plate, at least one exposure is performed on the production line wafer, in each photolithography process, the binary intensity mask pattern 21 is transferred to the production line wafer to obtain a first reference pattern, and the phase shift mask pattern 22 is transferred to the production line wafer to obtain a first process pattern.

[0044] Next, step S3 is performed: measuring the critical dimensions of the first reference pattern and the critical dimensions of the first process pattern in each photolithography process, and obtaining the deviation of the critical dimensions of the first reference pattern and the critical dimensions of the first process pattern.

[0045] Preferably, the critical dimensions of the first reference pattern at least include the line width of the straight line in the first reference pattern, the distance between the straight lines in the first reference pattern; and the critical dimensions of the first process pattern at least include the line width of the straight line in the first process pattern, the distance between the straight lines in the first process pattern.

[0046] Further, step S4 is performed: before the phase shift mask plate is returned to the factory for cleaning, the deviation of the critical dimensions of the first reference pattern and the critical dimensions of the first process pattern in each photolithography process is monitored, and it is ensured that the deviation of the critical dimensions of the first reference pattern and the critical dimensions of the first process pattern is within a preset deviation range.

[0047] Specifically, the deviation of the critical dimensions of the second reference pattern and the second process pattern at least includes: the deviation of the distance between lines in the second reference pattern and the distance between lines in the second process pattern, and the deviation of the distance between lines in the second reference pattern and the distance between lines in the second process pattern.

[0048] In the embodiment, the preset deviation interval is [-3nm, 3nm].

[0049] Then, step S5 is performed: after the phase shift mask is returned to the factory for cleaning, the phase shift mask is used to expose a test wafer once, so as to transfer the binary intensity mask pattern 21 to the test wafer to obtain a second reference pattern, and transfer the phase shift mask pattern 22 to the test wafer to obtain a second process pattern.

[0050] Further, step S6 is performed: the critical dimensions of the second reference pattern and the second process pattern are measured, and the deviation of the critical dimensions of the second reference pattern and the second process pattern is obtained.

[0051] Preferably, the critical dimensions of the second reference pattern at least include: the line width of the lines in the second reference pattern, the distance between lines in the second reference pattern; the critical dimensions of the second process pattern at least include: the line width of the lines in the second process pattern, the distance between lines in the second process pattern.

[0052] Specifically, the deviation of the critical dimensions of the second reference pattern and the second process pattern at least includes: the deviation of the distance between lines in the second reference pattern and the distance between lines in the second process pattern, and the deviation of the distance between lines in the second reference pattern and the distance between lines in the second process pattern.

[0053] Finally, step S7 is performed: it is judged whether the deviation of the critical dimensions of the second reference pattern and the second process pattern is in the preset deviation interval. If the deviation of the critical dimensions of the second reference pattern and the second process pattern is in the preset deviation interval, it is determined that the mask returned to the factory for cleaning is normal. If the deviation of the critical dimensions of the second reference pattern and the second process pattern is not in the preset deviation interval, it is determined that the mask returned to the factory for cleaning is abnormal.

[0054] Since the BIM pattern 21 is not affected by the cleaning in the factory, the second reference pattern transferred from the BIM pattern 21 to the test wafer can be used as a reference pattern to monitor whether the second process pattern is abnormal, so that whether the phase shift mask pattern (PSM pattern) 22 on the mask (reticle) is damaged due to excessive cleaning in the factory can be monitored.

[0055] In the present application, by using the difference in cleaning resistance between the binary intensity mask (BIM) pattern and the phase shift mask (PSM) pattern, a set of BIM patterns and a set of PSM patterns are designed on the phase shift mask, and then the BIM patterns and the PSM patterns are transferred to the production line wafer in the daily lithography process to obtain the first reference pattern and the first process pattern. The cleaning-resistant BIM pattern (first reference pattern) is used as a reference pattern to monitor and ensure that the deviation of the critical dimension of the first reference pattern and the first process pattern falls within the preset deviation interval. Then, after cleaning in the factory, the phase shift mask is used to expose the test wafer, and the BIM patterns and the PSM patterns are transferred to the test wafer to obtain the second reference pattern and the second process pattern. Finally, the cleaning-resistant BIM pattern (second reference pattern) is used as a reference pattern to determine whether the deviation of the critical dimension of the second reference pattern and the critical dimension of the second process pattern is within the preset deviation interval. If the deviation is not within the preset deviation interval, it is determined that the cleaning of the mask in the factory is abnormal (excessive cleaning). The method for monitoring the abnormal cleaning of the mask in the factory provided in the present application can actually consider the problem of the influence of the phase shift mask on the wafer during subsequent exposure, and can efficiently and accurately monitor whether the cleaning of the phase shift mask is abnormal, avoiding the problem that the phase shift mask is excessively cleaned during cleaning in the factory, which affects subsequent lithography.

[0056] Based on the same inventive concept, the present application also provides a phase shift mask layout used in the method for monitoring the abnormal cleaning of the mask in the factory. Figure 3 The phase shift mask layout includes a base plate 11, a binary intensity mask pattern 21, and a phase shift mask pattern 22 located on the side of the binary intensity mask pattern 21. The binary intensity mask pattern 21 and the phase shift mask pattern 22 are respectively arranged on the base plate 11.

[0057] Obviously, the above embodiments are only examples for clarity and do not limit the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all embodiments are not exhaustively enumerated. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A method of monitoring abnormality of a reticle factory clean, characterized by, The method comprises the following steps: designing a set of binary intensity mask patterns and a set of phase shift mask patterns on a phase shift mask plate, the phase shift mask patterns being located on the sides of the binary intensity mask patterns; using the phase shift mask plate to perform at least one exposure on a production wafer, in each photolithography process, the binary intensity mask patterns are transferred to the production wafer to obtain first reference patterns, and the phase shift mask patterns are transferred to the production wafer to obtain first process patterns; measuring the critical dimensions of the first reference patterns and the critical dimensions of the first process patterns in each photolithography process, and obtaining the deviation of the critical dimensions of the first reference patterns and the critical dimensions of the first process patterns; monitoring the deviation of the critical dimensions of the first reference patterns and the critical dimensions of the first process patterns in each photolithography process before the phase shift mask plate is returned to the factory for cleaning, and ensuring that the deviation of the critical dimensions of the first reference patterns and the critical dimensions of the first process patterns is within a preset deviation range; after the phase shift mask plate is returned to the factory for cleaning, using the phase shift mask plate to perform one exposure on a test wafer, so as to transfer the binary intensity mask patterns to the test wafer to obtain second reference patterns, and transfer the phase shift mask patterns to the test wafer to obtain second process patterns; measuring the critical dimensions of the second reference patterns and the critical dimensions of the second process patterns, and obtaining the deviation of the critical dimensions of the second reference patterns and the critical dimensions of the second process patterns; determining whether the deviation of the critical dimensions of the second reference patterns and the critical dimensions of the second process patterns is within the preset deviation range, if the deviation of the critical dimensions of the second reference patterns and the critical dimensions of the second process patterns is within the preset deviation range, it is determined that the cleaning of the photomask returned to the factory is normal; if the deviation of the critical dimensions of the second reference patterns and the critical dimensions of the second process patterns is not within the preset deviation range, it is determined that the cleaning of the photomask returned to the factory is abnormal.

2. The method of claim 1, wherein The preset deviation range is [-3nm, 3nm].

3. The method of claim 1, wherein the step of monitoring the abnormality of the return clean of the photomask is performed by a photomask inspection apparatus. The critical dimensions of the first reference patterns at least include the line width of straight lines in the first reference patterns, the distance between straight lines in the first reference patterns; the critical dimensions of the first process patterns at least include the line width of straight lines in the first process patterns, the distance between straight lines in the first process patterns.

4. The method of claim 1, wherein the step of monitoring the abnormality of the return clean of the photomask is performed by a computer system. 5 The critical dimensions of the second reference patterns at least include the line width of straight lines in the second reference patterns, the distance between straight lines in the second reference patterns; the critical dimensions of the second process patterns at least include the line width of straight lines in the second process patterns, the distance between straight lines in the second process patterns.

5. The method for monitoring abnormalities during photomask return cleaning according to claim 1, characterized in that, The phase shift mask plate comprises a base plate, a phase shift film layer and a light shielding film layer, the phase shift film layer is located on the base plate, and the light shielding film layer is located on the phase shift film layer.

6. The method of claim 5, wherein the step of monitoring the abnormality of the return clean of the photomask is performed by using a plurality of sensors. 5 The binary intensity mask patterns comprise a first patterned phase shift film layer located on the base plate and a patterned light shielding film layer covering the first patterned phase shift film layer.

7. The method of claim 5, wherein the step of monitoring the abnormality of the return clean of the photomask is performed by using a plurality of sensors. 7 The phase shift mask patterns comprise a second patterned phase shift film layer located on the base plate.

8. The method of claim 5, wherein the step of monitoring the abnormality of the return clean of the photomask is performed by a computer system. 5 The material of the phase shift film layer is molybdenum silicon.

9. The method of claim 5, wherein the step of monitoring the abnormality of the return clean of the photomask is performed by a photomask inspection apparatus. 5 The material of the light shielding film layer is metal chromium.

10. A phase shift mask reticle layout for use in a method of monitoring abnormality of a cleaning of a reticle according to any one of claims 1 to 9, wherein, Comprise: A base plate, a binary intensity mask pattern and a phase shift mask pattern located at the side of the binary intensity mask pattern, the binary intensity mask pattern and the phase shift mask pattern are respectively arranged on the base plate.

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