Phase shift mask and method of manufacturing the same

Abstract

The application provides a phase shift mask and a manufacturing method thereof. In the application, a second key pattern size corresponding to a second photoetching process is obtained, and a second photoetching machine is obtained according to the second key pattern size. The resolution identification ability of the obtained second photoetching machine is matched with the second key pattern size, so that the problem that the resolution ability of the photoetching machine used in the second photoetching process is not enough and the formed phase shift mask is defective is avoided, and the quality of the phase shift mask is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a phase-shifting mask and its manufacturing method. Background Technology

[0002] Photolithography is one of the key processes in semiconductor manufacturing. It transfers the design pattern from a photomask to a photoresist layer on a wafer. However, in binary photolithography masks, edge scattering reduces overall contrast, making it impossible to obtain the desired pattern. As feature sizes continue to shrink, the requirements for photolithography become increasingly stringent. Phase-shift masks (PSMs) are widely used because they significantly improve pattern contrast and resolution.

[0003] Currently used phase-shifting masks typically involve adding a phase-shifting material layer to a binary mask (quartz and an opaque layer). The process involves data processing, electron beam exposure and development, etching onto the quartz surface, a second exposure and development, etching of the opaque layer, and analysis and detection of phase shift and defects to ensure design requirements are met. Electron beam exposure is the first exposure, opening the desired pattern in the design area and etching it onto the quartz surface. Ensuring the accuracy of critical pattern dimensions requires a high-precision exposure machine for this first exposure. The second exposure removes the opaque layer from the transparent areas of the design area; this is typically a large-area removal, so a low-precision exposure machine is sufficient for this second exposure.

[0004] However, through long-term production practice, technicians have found that because the resolution of the pattern size during the second exposure was not considered during the preparation of the phase shift mask, especially when the second low-precision exposure machine does not have the resolution capability for this size, the final phase shift mask usually produces a large number of defects. Summary of the Invention

[0005] The purpose of this invention is to provide a phase-shifting mask and its manufacturing method to solve the problem of existing phase-shifting masks generating a large number of defects, which leads to reduced quality.

[0006] To solve the above-mentioned technical problems, the present invention provides a method for manufacturing a phase-shifting mask, comprising:

[0007] A mask substrate is provided, the mask substrate comprising a substrate and a phase shift layer and an opaque layer sequentially formed on the substrate;

[0008] Obtain the first key pattern size corresponding to the first photolithography process, and obtain the first photolithography machine based on the first key pattern size;

[0009] Obtain the second key pattern size corresponding to the second photolithography process, and obtain the second photolithography machine based on the second key pattern size;

[0010] The first lithography process is performed on the mask substrate using the first lithography machine, wherein the first lithography process sequentially etches the opaque layer and the phase shift layer;

[0011] The second lithography machine is used to perform a second lithography process on the mask substrate after the first lithography process, wherein the second lithography process etches the opaque layer a second time.

[0012] Optionally, the method for obtaining the size of the first key graphic includes:

[0013] Acquire and process the mask pattern to obtain all the first pattern sizes corresponding to the first photolithography process;

[0014] Sort all the first graphic dimensions and select the first graphic dimension with the smallest value and record it as the first key graphic dimension.

[0015] Optionally, the method for obtaining the second key graphic dimension includes:

[0016] Acquire and process the mask pattern to obtain all the second pattern dimensions corresponding to the second photolithography process;

[0017] Sort all the second graphic dimensions and select the second graphic dimension with the smallest value and record it as the second key graphic dimension.

[0018] Optionally, before acquiring the second lithography machine, the method further includes:

[0019] Provide a third lithography machine, wherein the precision of the third lithography machine is less than that of the second lithography machine;

[0020] Confirm whether all the second pattern dimensions meet the resolution capability of the third lithography machine. If yes, use the third lithography machine to perform the second lithography process on the mask substrate after the first lithography process. If not, obtain the second lithography machine.

[0021] Optionally, before performing a second lithography process on the mask substrate after the first lithography process using the third lithography machine, the method further includes:

[0022] The second pattern size that does not meet the resolution capability of the third lithography machine is selected and recorded as the pattern size to be confirmed;

[0023] Determine whether the pattern to be confirmed can be modified. If yes, modify the pattern to be confirmed and use the third lithography machine to perform the second lithography process on the mask substrate after the first lithography process. If no, obtain the second lithography machine.

[0024] Optionally, the method for obtaining the first lithography machine includes: providing a first matching table, and searching the first matching table according to the first key pattern size to obtain the first lithography machine.

[0025] Optionally, the method for obtaining the second lithography machine includes: providing a second matching table, and searching the second matching table according to the second key pattern size to obtain the second lithography machine.

[0026] Optionally, after performing the second photolithography process, the method further includes: detecting whether the phase-shift mask is qualified.

[0027] Optionally, the testing items for determining whether the phase-shift mask is qualified include: defect detection, phase shift detection, and transmittance detection.

[0028] To address the above problems, the present invention also provides a phase-shifting mask, which is prepared according to the manufacturing method of the phase-shifting mask described in any one of the above claims.

[0029] The present invention discloses a phase-shifting mask and its manufacturing method. By obtaining the second key pattern size corresponding to the second photolithography process and obtaining the second photolithography machine based on the second key pattern size, the resolution and recognition capability of the obtained second photolithography machine is matched with the second key pattern size. This avoids the problem of excessive defects in the final phase-shifting mask caused by insufficient resolution capability of the photolithography machine used in the second photolithography process, thereby improving the quality of the phase-shifting mask. Attached Figure Description

[0030] Figure 1 This is a flowchart of a method for manufacturing a phase-shifting mask according to an embodiment of the present invention;

[0031] Figures 2 to 5 This is a schematic diagram of the process of fabricating a phase-shift mask according to an embodiment of the present invention;

[0032] The accompanying figure is labeled as follows:

[0033] 1-Substrate;

[0034] 2-Phase shift layer;

[0035] 3-Opaque layer;

[0036] 4-Mask layer. Detailed Implementation

[0037] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a further detailed explanation of the phase-shifting mask and its manufacturing method proposed in this invention. The advantages and features of this invention will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise scales, intended only to facilitate and clarify the illustration of the embodiments of this invention. Furthermore, the structures shown in the drawings are often part of the actual structures. In particular, different figures may emphasize different aspects and sometimes use different scales.

[0038] Figure 1 This is a flowchart of a method for manufacturing a phase-shifting mask according to an embodiment of the present invention; Figures 2 to 5 This is a schematic diagram illustrating the process of fabricating a phase-shift mask according to an embodiment of the present invention. The following is in conjunction with... Figures 1 to 5 The manufacturing method of the phase shift mask in this embodiment is described in detail.

[0039] In step S10, as Figure 2 As shown, a mask substrate is provided, the mask substrate including a substrate 1 and a phase shift layer 2 and an opaque layer 3 sequentially formed on the substrate 1.

[0040] In this embodiment, the substrate 1 is a quartz substrate, the phase shift layer 2 is formed on the substrate 1, and the opaque layer 3 is formed on the phase shift layer 2. Furthermore, in this embodiment, after forming the phase shift layer 2 and the opaque layer 2 on the substrate 1, a first photolithography process and a second photolithography process are required to form the final fabricated phase shift mask. To perform the first and second photolithography processes, a suitable first photolithography machine must be selected for performing the first photolithography process, and a suitable second photolithography machine must be selected for performing the second photolithography process. Therefore, the following steps S20 to S30 are provided to select the suitable first and second photolithography machines.

[0041] In step S20, the first key pattern size corresponding to the first photolithography process is obtained, and the first photolithography machine is obtained based on the first key pattern size. In this embodiment, the method for obtaining the first key pattern size includes the following steps S201 and S202.

[0042] In step S201, the mask pattern is acquired and processed to obtain all the first pattern sizes corresponding to the first photolithography process.

[0043] In this embodiment, the mask pattern refers to the pattern ultimately formed on the phase-shift mask. Before fabricating the phase-shift mask, technicians first create a phase-shift mask layout, on which multiple layout patterns are drawn. Then, based on the phase-shift mask layout, multiple layout patterns are copied onto the phase-shift mask using a mask etching process to form the multiple patterns on the phase-shift mask. These multiple patterns constitute the mask pattern. The mask pattern includes, for example, vias, source lines, word lines, etc. Furthermore, in this embodiment, data processing of the mask pattern may include: data processing, standardization, and inspection of the mask pattern, ultimately forming pattern data that can be acquired and recognized by a lithography machine. In addition, in this embodiment, since the first lithography process corresponds to the sequential etching of the opaque layer 3 and the phase-shift layer 2, the first pattern size is the size corresponding to the pattern simultaneously formed on the opaque layer 3 and the phase-shift layer 2.

[0044] In step S202, all the first graphic dimensions are sorted, and the first graphic dimension with the smallest value is selected and recorded as the first key graphic dimension.

[0045] In this embodiment, if the lithography machine can analyze and identify the smallest size among the first pattern sizes, then any size larger than the first pattern size can also be analyzed and identified by the lithography machine. Therefore, in this embodiment, after selecting the first key pattern size corresponding to the smallest first pattern size, the first lithography machine selected based on the first key pattern size will necessarily meet the requirements for performing the first lithography process.

[0046] Furthermore, in this embodiment, the method for obtaining the first lithography machine includes: providing a first matching table, and searching the first matching table according to the first key pattern size to obtain the first lithography machine.

[0047] In this embodiment, based on long-term technical practice and research, technicians have formed a first matching table. The first matching table includes multiple graphic sizes and the model and resolution and identification capability data of the lithography machine corresponding to each graphic size. Therefore, when obtaining the first lithography machine, the first lithography machine can be obtained by searching the first matching table through the first key graphic size.

[0048] In step S20, the second key pattern size corresponding to the second photolithography process is obtained, and the second photolithography machine is obtained based on the second key pattern size.

[0049] In this embodiment, the second key pattern size corresponding to the second lithography process is obtained, and the second lithography machine is obtained based on the second key pattern size. This ensures that the resolution and recognition capability of the obtained second lithography machine matches the second key pattern size. This avoids the problem of insufficient resolution capability of the lithography machine used in performing the second lithography process, which could lead to excessive defects in the final phase-shift mask, thereby improving the quality of the phase-shift mask.

[0050] In this embodiment, the method for obtaining the size of the second key graphic includes the following steps S210 and S220.

[0051] In step S210, the mask pattern is acquired and processed to obtain all the second pattern dimensions corresponding to the second photolithography process.

[0052] In this embodiment, the method for acquiring and processing the mask pattern is as described in step S01 above, and will not be repeated here. It is worth noting that in this embodiment, acquiring and processing the mask pattern can be completed simultaneously in step S01, or it can be completed in this step. That is, the acquisition and processing of all the mask patterns can be completed simultaneously in step S01, or only the mask pattern corresponding to the first photolithography process can be acquired and processed. The acquisition and processing of the mask pattern corresponding to the second photolithography process is completed in step S210. Specific details are not elaborated here, and the actual requirements shall prevail.

[0053] Furthermore, in this embodiment, since the second photolithography process corresponds to the secondary etching of the opaque layer 3, the second pattern size is the size corresponding to the pattern formed when the opaque layer 3 is etched twice.

[0054] In step S202, all the second graphic dimensions are sorted, and the second graphic dimension with the smallest value is selected and recorded as the second key graphic dimension.

[0055] In this embodiment, if the lithography machine can analyze and identify the smallest size corresponding to the second pattern size, then the size corresponding to the second pattern size that is larger than the second pattern size can also be analyzed and identified by the lithography machine. Therefore, in this embodiment, after selecting the second key pattern size corresponding to the second pattern size with the smallest value, the second lithography machine selected by the second key pattern size will necessarily meet the requirements for performing the second lithography process.

[0056] Furthermore, in this embodiment, the method for obtaining the second lithography machine includes: providing a second matching table, and searching the second matching table according to the second key pattern size to obtain the second lithography machine.

[0057] In this embodiment, based on long-term technical practice and research, technicians have developed a second matching table. This table includes multiple pattern sizes and the corresponding lithography machine model and its resolution and identification capabilities for each pattern size. Therefore, when acquiring the second lithography machine, the second lithography machine can be obtained by searching the second matching table using the second key pattern size. Furthermore, in this embodiment, the second matching table is different from the first matching table. In an optional embodiment, the first and second matching tables are the same; that is, searching the same matching table will retrieve both the first and second lithography machines. This saves manufacturing time for the phase-shifting mask.

[0058] Furthermore, in this embodiment, before acquiring the second lithography machine, the method further includes the following steps one and two.

[0059] In step one, a third lithography machine is provided, wherein the precision of the third lithography machine is less than that of the second lithography machine.

[0060] In step two, it is confirmed whether all the dimensions of the second pattern meet the resolution capability of the third lithography machine. If so, the third lithography machine is used to perform the second lithography process on the mask substrate after the first lithography process. If not, the second lithography machine is obtained.

[0061] That is, in this embodiment, if the third lithography machine with lower precision is sufficient to meet the resolution requirements for the second pattern size when performing the second lithography process according to the existing method for manufacturing phase-shifting masks, then the third lithography machine with lower precision is used to perform the second lithography process. This eliminates the need for the more precise and expensive second lithography machine, thereby reducing costs.

[0062] Furthermore, in this embodiment, before performing a second lithography process on the mask substrate after the first lithography process using the third lithography machine, the method further includes the following first step and second step.

[0063] In the first step, the second pattern size that does not meet the resolution capability of the third lithography machine is selected and recorded as the pattern size to be confirmed.

[0064] In the second step, it is determined whether the pattern to be confirmed can be modified. If so, the pattern to be confirmed is modified, and the second lithography process is performed on the mask substrate after the first lithography process using the third lithography machine. If not, the second lithography machine is obtained.

[0065] In this embodiment, the method for modifying the pattern to be confirmed includes: enlarging the size of the pattern to be confirmed or deleting the pattern to be confirmed. In this embodiment, the pattern to be confirmed that can be enlarged or deleted is typically an erroneous pattern resulting from design errors during the design of the mask layout, such as redundant or abnormal patterns; or the pattern to be confirmed may be an unimportant pattern that will not affect the final phase-shift mask structure. Thus, enlarging or deleting the pattern to be confirmed will not affect the final phase-shift mask. In this embodiment, by modifying the pattern to be confirmed so that the dimensions of all the second patterns can meet the resolution capability of the third lithography machine, the second lithography process is performed using the third lithography machine with lower precision. This eliminates the need for the more precise and expensive second lithography machine, thereby reducing costs.

[0066] Furthermore, in this embodiment, step S10 can be performed before steps S20 and S30. In an optional embodiment, steps S20 and S30 can also be performed before step S10. The order in which steps S10, S20, and S30 are performed is not specifically limited here, but depends on the actual situation.

[0067] In step S40, the reference Figure 3 As shown, the first lithography machine is used to perform the first lithography process on the mask substrate, wherein the first lithography process etches the opaque layer 3 and the phase shift layer 2 in sequence.

[0068] Combination Figure 2 and participate Figure 3 As shown, in this embodiment, a photoresist layer (not shown) is formed on the opaque layer 3. The mask substrate is placed in the first photolithography machine, and the opaque layer 3 and the phase shift layer 2 are etched sequentially using the photoresist layer as a mask, thereby forming patterned opaque layer 3 and phase shift layer 2. After performing the first photolithography process, the patterns formed in the opaque layer 3 and phase shift layer 2 are identical. After performing the first photolithography process, the photoresist layer (not shown) located on the opaque layer 3 is removed. In this embodiment, the process for removing the photoresist layer (not shown) is an ashing process.

[0069] In step S50, as Figure 4 and Figure 5 As shown, the second lithography machine is used to perform a first lithography process on the mask substrate after the first lithography process, wherein the second lithography process etches the opaque layer 3 a second time.

[0070] In this embodiment, before performing the second photolithography process, a mask layer 4 is formed on the opaque layer 3. Then, using the mask layer 4 as a mask, the second photolithography process is performed to etch the opaque layer 3 a second time, thereby re-patterning the opaque layer 3. Furthermore, in this embodiment, the material forming the mask layer 4 is photoresist, and after performing the second photolithography process, an ashing process is performed to remove the mask layer 4 to form the phase-shifting mask.

[0071] Furthermore, after performing the second photolithography process, the method further includes: detecting whether the phase-shifting mask is qualified. The detection items for determining whether the phase-shifting mask is qualified include: defect detection, phase shift detection, and transmittance detection.

[0072] Furthermore, this embodiment also provides a phase-shifting mask, which is prepared according to the manufacturing method of the phase-shifting mask described in any one of the above embodiments.

[0073] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to mutually. In addition, different parts between embodiments can also be combined with each other, and this invention does not limit this.

[0074] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A method for manufacturing a phase-shifting mask, characterized in that, include: A mask substrate is provided, the mask substrate comprising a substrate and a phase shift layer and an opaque layer sequentially formed on the substrate; Obtain the first key pattern size corresponding to the first photolithography process, and obtain the first photolithography machine based on the first key pattern size; Obtain the second key pattern size corresponding to the second photolithography process, and obtain the second photolithography machine based on the second key pattern size; wherein, the method for obtaining the second key pattern size includes: obtaining and processing the mask pattern to obtain all the second pattern sizes corresponding to the second photolithography process; sorting all the second pattern sizes, and selecting the second pattern size with the smallest value and recording it as the second key pattern size; The first lithography process is performed on the mask substrate using the first lithography machine, wherein the first lithography process sequentially etches the opaque layer and the phase shift layer; The second lithography machine is used to perform a second lithography process on the mask substrate after the first lithography process, wherein the second lithography process etches the opaque layer a second time. Before acquiring the second lithography machine, the method further includes: Provide a third lithography machine, wherein the precision of the third lithography machine is less than that of the second lithography machine; Confirm whether all the second pattern dimensions meet the resolution capability of the third lithography machine. If yes, use the third lithography machine to perform the second lithography process on the mask substrate after the first lithography process. If not, obtain the second lithography machine.

2. The method for manufacturing a phase-shifting mask as described in claim 1, characterized in that, The method for obtaining the size of the first key graphic includes: Acquire and process the mask pattern to obtain all the first pattern sizes corresponding to the first photolithography process; Sort all the first graphic dimensions and select the first graphic dimension with the smallest value and record it as the first key graphic dimension.

3. The method for manufacturing a phase-shifting mask as described in claim 1, characterized in that, Before performing a second lithography process on the mask substrate after the first lithography process using the third lithography machine, the method further includes: The second pattern size that does not meet the resolution capability of the third lithography machine is selected and recorded as the pattern size to be confirmed; Determine whether the pattern to be confirmed can be modified. If yes, modify the pattern to be confirmed and use the third lithography machine to perform the second lithography process on the mask substrate after the first lithography process. If no, obtain the second lithography machine.

4. The method for manufacturing a phase-shifting mask as described in claim 1, characterized in that, The method for obtaining the first lithography machine includes: Provide a first matching table, and search the first matching table based on the first key graphic size to obtain... The first lithography machine.

5. The method for manufacturing a phase-shifting mask as described in claim 1, characterized in that, The method for obtaining the second lithography machine includes: A second matching table is provided, and the second matching table is used to find the desired value based on the second key graphic dimension. The second lithography machine.

6. The method for manufacturing a phase-shifting mask as described in claim 1, characterized in that, After performing the second photolithography process, the method further includes: detecting whether the phase-shift mask is qualified.

7. The method for manufacturing a phase-shifting mask as described in claim 1, characterized in that, The testing items for determining whether the phase-shift mask is qualified include: defect detection, phase shift detection, and transmittance detection.

8. A phase-shifting mask, characterized in that, It is prepared according to the manufacturing method of the phase shift mask as described in any one of claims 1 to 7 above.

Images