Photomask defect detection method and system and computer readable medium

Abstract

The invention provides a photomask defect detection method and system and a computer readable medium, and belongs to the field of photomasks. The photomask defect detection method comprises the steps that a photomask is provided, the photomask comprises a graphic area and a light-proof area, detection parameters of the graphic area and the light-proof area are set through a detection machine table, the sensitivity of penetrating light of the graphic area is set to be V1, the sensitivity of reflected light is set to be V2, and meanwhile the sensitivity of penetrating light of the light-proof area is set to be V3; the sensitivity of the reflected light is set to be 0, V1, V2 and V3 are all not equal to 0, and V3 is smaller than V1. And turning on a detection light source to scan and detect the photomask based on the set detection parameters of the graphic area and the light-proof area. According to the invention, the sensitivity of the reflected light of the light-proof area is set to be 0, and the graphic area and the light-proof area can be scanned and detected at the same time through the detection machine, so that the detection time is shortened, and the problem of missing grabbing defect of the detection machine is solved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a photomask defect detection method, system and computer-readable medium. Background Art

[0002] Phase Shift Mask (PSM) is a resolution enhancement technology that uses both the intensity and phase of light to form an image and obtain a higher resolution. Phase shift mask is a method of improving lithography resolution by changing the phase of the light beam. Its basic principle is to change the mask structure so that the light waves passing through adjacent light-transmitting areas produce a 180-degree phase difference. The two will cause destructive interference in a specific area on the image plane, reducing the light intensity of the dark field in the light field and increasing the light field in the bright area to improve contrast and resolution.

[0003] Phase-shift mask is also called photomask. Once a defect occurs in the photomask, the defect will be transmitted to each chip or wafer, directly affecting the yield of the etching process, and even causing the scrapping of the entire batch of products. Therefore, the elimination of photomask defects is of great significance to the improvement of product quality. To eliminate photomask defects, it is first necessary to inspect the defects of the photomask. Photomask defect inspection requires inspection of the graphic area and the pure black area (i.e., opaque area) around the graphic area to obtain the defects in the graphic area and the opaque area, so as to correct the graphic area and the opaque area, reduce the number of defects in the graphic area and the opaque area, and improve the yield of subsequent etching processes. Because the material of the graphic area is different from that of the pure black area. The material of the graphic area includes glass and molybdenum silicon deposited on the surface of the glass. The material of the pure black area includes glass and metal chromium (Cr) deposited on the surface of the glass. The prior art generally uses the following two methods to inspect the graphic area and the pure black area:

[0004] 1. The graphic area and the pure black area are inspected separately. In the specific operation, the graphic area is first scanned and inspected, and this step takes 2 hours or more. Then, the pure black area is scanned and inspected, and the operation time in this step is more than 1 hour. Therefore, this method has the defect of long inspection time.

[0005] 2. Inspect the graphic area and the pure black area together. The inspection machine needs to use the Tri-tone inspection mode, that is, select three materials to inspect the graphic area and the pure black area. However, this method needs to reduce the contrast of the graphic area when setting the inspection parameters. Therefore, there is a risk of missing defects when inspecting defects in the graphic area.

[0006] Therefore, the existing photomask inspection method has the defects of long inspection time and missed defects.

[0007] It should be noted that the information disclosed in the background technology section of the invention is only intended to deepen the understanding of the general background technology of the invention, and should not be regarded as an admission or suggestion in any form that the information constitutes prior art already known to those skilled in the art. Summary of the invention

[0008] The object of the present invention is to provide a method, system and computer-readable medium for detecting photomask defects, so as to solve the problems of long detection time and defect omission when detecting photomask defects.

[0009] In order to solve the above technical problems, the present invention provides a method for detecting photomask defects, comprising:

[0010] Providing a photomask, the photomask comprising a graphic area and an opaque area, wherein the opaque area is arranged around the graphic area;

[0011] Loading the photomask into a testing machine, selecting the type of material to be tested through the testing machine, and screening out the graphic area and the opaque area from the photomask through the testing machine;

[0012] The detection parameters of the graphic area and the opaque area are set by the detection machine, including setting the sensitivity of the penetrating light of the graphic area to V1, the sensitivity of the reflected light to V2, and setting the sensitivity of the penetrating light of the opaque area to V3, and the sensitivity of the reflected light to 0, wherein V1, V2 and V3 are not equal to 0, and V3 is less than V1;

[0013] Based on the set inspection parameters of the graphic area and the opaque area, the inspection light source is turned on to scan and inspect the photomask.

[0014] Preferably, the material of the graphic area includes glass and molybdenum silicon deposited on the glass surface, and the material of the opaque area includes glass, molybdenum silicon deposited on the glass surface, and metal chromium deposited on the surface of molybdenum silicon.

[0015] Preferably, the type of material to be tested selected by the testing machine includes:

[0016] Through the selection mode of the material to be tested set by the detection machine, molybdenum silicide and glass are selected as the materials to be tested.

[0017] Preferably, the step of screening out the graphic area and the opaque area from the photomask by using a detection machine comprises:

[0018] Obtain the original coordinate file generated by the photomask during the design stage;

[0019] Based on the original coordinate file, the coordinates of the diagonal lines of the graphic area are input into the detection machine to screen out multiple graphic areas, and the coordinates of the diagonal lines of the opaque area are input into the detection machine to screen out the opaque area.

[0020] Preferably, the setting range of the sensitivity V1 of the penetrating light in the graphic area is 90-100, the setting range of the sensitivity V2 of the reflected light in the graphic area is 80-90, the setting range of the sensitivity V3 of the penetrating light in the opaque area is 70-80, and V3 is smaller than V1.

[0021] Preferably, the sensitivity V3 of the light penetrating through the opaque area is set to 80.

[0022] Preferably, the defect in the opaque area detected by the detection machine is a pinhole defect.

[0023] Preferably, the length and width of defects in the opaque area captured by the detection machine are both greater than or equal to 500 nm, and the length and width of defects in the graphic area captured by the detection machine are both greater than or equal to 10 nm.

[0024] Based on the same inventive concept, the present invention also provides a computer-readable medium on which a program is stored, including:

[0025] When the program is executed, at least part of the steps in the photomask defect detection method according to any one of claims 1 to 8 are performed.

[0026] Based on the same inventive concept, the present invention also provides a photomask defect detection system, comprising:

[0027] An acquisition module is used to load the photomask into a testing machine, select the type of material to be tested through the testing machine, and screen out the graphic area and the opaque area from the photomask through the testing machine;

[0028] An editing module, used to set the detection parameters of the graphic area and the opaque area through the detection machine, including setting the sensitivity of the penetrating light of the graphic area to V1, the sensitivity of the reflected light to V2, and setting the sensitivity of the penetrating light of the opaque area to V3, and the sensitivity of the reflected light to 0, wherein V1, V2 and V3 are not equal to 0, and V3 is less than V1;

[0029] The detection module is used to turn on the detection light source to scan and detect the photomask based on the set detection parameters of the graphic area and the opaque area.

[0030] Compared with the prior art, the photomask defect detection method of the present invention has the following advantages:

[0031] The present invention provides a photomask, which includes a graphic area and an opaque area, and the opaque area is arranged around the graphic area. The photomask is loaded into a detection machine, the type of material to be tested is selected by the detection machine, and the graphic area and the opaque area are screened out from the photomask by the detection machine. The parameters of the graphic area and the opaque area are set by the detection machine, including setting the sensitivity of the penetrating light of the graphic area to V1, the sensitivity of the reflected light to V2, and setting the sensitivity of the penetrating light of the opaque area to V3, and the sensitivity of the reflected light to 0, wherein V1, V2 and V3 are not equal to 0, and V3 is less than V1. Based on the set parameters of the graphic area and the opaque area, the detection light source is turned on to scan and detect the photomask. Therefore, the photomask defect detection method provided by the present invention sets the sensitivity of the reflected light in the opaque area to 0, and sets the sensitivity of the transmitted light in the opaque area to be lower than the sensitivity of the transmitted light in the graphic area, thereby reducing the sensitivity of the graphic area. The function of using different sensitivities in different detection areas of the inspection machine can be utilized to achieve all-in-one inspection of multiple materials of high-end photomasks. The inspection machine can be used to scan and inspect the graphic area and the opaque area at the same time, which not only shortens the detection time, but also solves the problem of the inspection machine missing defects.

[0032] The computer-readable medium and photomask defect detection system provided by the present invention belong to the same inventive concept as the photomask defect detection method provided by the present invention. Therefore, the computer-readable medium and photomask defect detection system provided by the present invention have at least all the advantages of the photomask defect detection system provided by the present invention, and can scan and detect the graphic area and the opaque area at the same time, while shortening the detection time and avoiding missing defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a flow chart of a photomask defect detection method in one embodiment of the present invention;

[0034] Figure 2 is a schematic structural diagram of a photomask in one embodiment of the present invention;

[0035] In the figure,

[0036] 100-glass; 200-graphic area;

[0037] 300-non-translucent area. DETAILED DESCRIPTION

[0038] In order to make the purpose, advantages and features of the present invention clearer, the photomask defect detection method, system and computer-readable medium proposed in the present invention are further described in detail in combination with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not in exact proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. It should be understood that the drawings in the specification do not necessarily show the specific structure of the present invention in proportion, and the illustrative features used to illustrate certain principles of the present invention in the drawings in the specification will also be slightly simplified. The specific design features of the present invention disclosed herein include, for example, specific dimensions, directions, positions and shapes, which will be determined in part by the specific application and use environment. In addition, in the embodiments described below, the same figure mark is sometimes used in common between different drawings to represent the same part or a part with the same function, and its repeated description is omitted. In this specification, similar numbers and letters are used to represent similar items, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0039] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0040] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0041] The core idea of ​​the present invention is to provide a photomask defect detection method, which can shorten the photomask defect detection time and avoid the problem of missing defects.

[0042] In order to realize the above idea, the present invention provides a method for detecting photomask defects. Figure 1 and Figure 2A specific implementation of a photomask defect detection method disclosed herein includes the following steps S1 to S4.

[0043] Step S1 : providing a photomask, wherein the photomask comprises a graphic region 200 and an opaque region 300 , wherein the opaque region 300 is disposed around the graphic region 200 .

[0044] Specifically, refer to Figure 1 and Figure 2 As shown, the photomask includes a graphic area 200 and an opaque area 300 located around the graphic area 200. The opaque area 300 is arranged around the graphic area 200. It should be noted that the photomask not only includes the graphic area 200 and the opaque area 300, but also includes alignment marks, edge bands and other parts. Since the present invention is not related to these parts, the description is omitted here. The graphic area 200 includes glass 100 and molybdenum silicon deposited on the surface of the glass 100. Glass 100 is a transparent material with a light transmittance of 100%. The light transmittance of molybdenum silicon is generally 6%, which is a light-shielding material used for photomasks. Molybdenum silicon material has a specific refractive index and thickness, and these parameters can be adjusted to make the light passing through the graphic area 200 produce a 180-degree phase difference with respect to the light in the opaque area 300. This phase difference can effectively reduce the diffraction effect, enhance the contrast between adjacent features, and thus improve the resolution. The material of the opaque area 300 includes glass 100 and chromium deposited on the surface of the glass 100. Since the light transmittance of metal chromium is 0%, a light-proof area 300 is formed in this area, which can also be called a pure black area. The photomask uses glass 100 as a substrate. A graphic area 200 is formed in an area where molybdenum silicon is deposited on the surface of the glass 100. The material of the light-proof area 300 includes glass 100, molybdenum silicon deposited on the surface of the glass 100, and metal chromium deposited on the surface of the molybdenum silicon.

[0045] Step S2: loading the photomask into a testing machine, selecting the type of material to be tested through the testing machine, and screening out the graphic area 200 and the opaque area 300 from the photomask through the testing machine.

[0046] Specifically, refer to Figure 1 and Figure 2As shown, the photomask is loaded into the inspection machine. When the inspection machine detects defects in the photomask, the first step in the inspection setting is to select the material to be tested of the photomask. There are three selection modes on the inspection machine, namely PSM, BIM and Tritone. In the PSM mode, two materials, molybdenum silicide and glass 100, are used as the materials to be tested. In the BIM mode, two materials, chromium and glass 100, are used as the materials to be tested. In the Tritone mode, three materials, molybdenum silicide, chromium, and glass 100, are used as the materials to be tested. In this embodiment, the first step in the inspection setting is to select the PSM mode, that is, to select two materials, molybdenum silicide and glass 100, as the materials to be tested.

[0047] Next, the pattern area 200 and the opaque area 300 are screened out from the photomask through a detection machine, including:

[0048] First, the original coordinate file generated by the photomask during the design phase is obtained. The inspection machine can obtain the coordinates of the graphic area 200 and the opaque area 300 from the original coordinate file of the photomask.

[0049] Then, the inspection machine selects multiple graphic areas 200 and opaque areas 300 based on the coordinates of the diagonal lines of the graphic area 200 and the coordinates of the diagonal lines of the opaque areas 300. The graphic area 200 is rectangular in shape. The opaque areas 300 are also rectangular and are arranged around the graphic area 200. The long side and short side of the graphic area 200 are equidistant from the long side and short side of the opaque areas 300. The coordinates of the diagonal lines of the graphic area 200, such as Figure 2 The coordinates of point A and point B are input into the detection machine, and the detection machine can filter out the graphic area 200. The detection machine is based on the coordinates of the diagonal line of the opaque area 300, for example Figure 2 The coordinates of point C and point D are input into the detection machine, and the detection machine will automatically remove the graphic area 200 at the corresponding coordinates, thereby screening out the opaque area 300.

[0050] Step S3: Setting the detection parameters of the graphic area 200 and the opaque area 300 through the detection machine, including setting the sensitivity of the transmitted light of the graphic area 200 to V1, and the sensitivity of the reflected light to V2, and setting the sensitivity of the transmitted light of the opaque area 300 to V3, and the sensitivity of the reflected light to 0, wherein V1, V2 and V3 are not equal to 0, and V3 is less than V1.

[0051] Specifically, refer to Figure 1 and Figure 2As shown, the scanning parameters of the graphic area 200 and the opaque area 300 are set by the detection machine, including setting the sensitivity of the penetrating light of the graphic area 200 to V1, and setting the sensitivity of the reflected light of the graphic area 200 to V2. Set the sensitivity of the penetrating light of the opaque area 300 to V3. Set the sensitivity of the reflected light of the opaque area 300 to 0. Among them, V1, V2 and V3 are not equal to 0, and V3 is less than V1. The setting range of the sensitivity V1 of the penetrating light of the graphic area 200 is 90-100. That is, the sensitivity of the penetrating light of the graphic area 200 can be set to 90, 95, 100, or any value in the range of 90-100. The setting range of the sensitivity V2 of the reflected light of the graphic area 200 is 80-90. That is, the sensitivity of the reflected light of the graphic area 200 can be set to 80, 85, 90, or any value in the range of 80-90. The setting range of the sensitivity V3 of the penetrating light of the opaque area 300 is 70-80. That is, the sensitivity of the penetrating light of the opaque area 300 can be set to 70, 75, 80, or any value in the range of 70-80. However, the sensitivity of the reflected light of the opaque area 300 is set to 0, and V3 is less than V1 when setting the parameters. Among them, sensitivity refers to the sensitivity of the detection machine to defect capture. It should be noted that the detection parameters of the graphic area 200 and the opaque area 300 set by the detection machine include not only the setting of sensitivity, but also the setting of other parameters, such as the setting of the penetrating light edge and the penetrating light angle of the graphic area 200. It also includes the setting of the penetrating light edge and the penetrating light angle of the opaque area 300. The setting of other parameters of the graphic area 200 and the opaque area 300 belongs to the prior art. For those skilled in the art, they are already familiar with the specific setting process and will not be elaborated here.

[0052] Step S4: Based on the set inspection parameters of the graphic area 200 and the opaque area 300 , turn on the inspection light source to scan and inspect the photomask.

[0053] Specifically, refer to Figure 1 and Figure 2 As shown, based on the parameters of the set graphic area 200 and the opaque area 300, the detection light source is turned on to scan and detect the photomask. The detection light source of the detection machine can be a laser beam with a wavelength of 157nm, 193nm, 248nm or 257nm projected onto the photomask. In this embodiment, a laser light source with a wavelength of 193nm is preferred.

[0054] The detection machine only captures pinhole-type defects in the opaque area 300. Pinhole-type defects are generally irregular patterns. When detecting, the detection machine controls the length and width of this type of defect. That is, the detection machine captures defects with a length and width greater than or equal to 500nm. When there is a pinhole-type defect in the opaque area 300, at the defect, the material of the opaque area 300 is glass and molybdenum silicon deposited on the surface of the glass, or the material of the opaque area 300 is only glass. When the detection machine detects defects in the graphic area 200, it not only captures pinhole-type defects, but also defects such as particle defects that fall on the graphic area 200 and traces formed in the graphic area 200. During detection, defects in the graphic area 200 with a length and width greater than or equal to 10nm are also captured.

[0055] In this embodiment, the chromium material of the opaque area 300 is treated as molybdenum silicon material to reduce the sensitivity of the penetrating light of the opaque area 300, and the sensitivity of the reflected light of the opaque area 300 is set to 0. The inspection machine simultaneously scans and inspects the graphic area 200 and the opaque area 300. The inspection machine can use different sensitivities for different inspection areas to achieve unified inspection of multiple materials of the photomask. While shortening the inspection time, it can also solve the risk of missing defects.

[0056] To realize the above idea, the embodiment further discloses a computer-readable medium on which a program is stored, including:

[0057] When the program is executed, at least part of the steps in the above-mentioned photomask defect detection method are performed.

[0058] To realize the above idea, the embodiment also discloses a photomask defect detection system, including:

[0059] An acquisition module is used to load the photomask into a testing machine, select the type of material to be tested through the testing machine, and screen out the graphic area 200 and the opaque area 300 from the photomask through the testing machine;

[0060] An editing module, used to set the detection parameters of the graphic area 200 and the opaque area 300 through the detection machine, including setting the sensitivity of the transmitted light of the graphic area 200 to V1 and the sensitivity of the reflected light to V2, and setting the sensitivity of the transmitted light of the opaque area 300 to V3 and the sensitivity of the reflected light to 0, wherein V1, V2 and V3 are not equal to 0, and V3 is less than V1;

[0061] The detection module is used to turn on the detection light source to scan and detect the photomask based on the set detection parameters of the graphic area 200 and the opaque area 300.

[0062] The computer-readable medium and photomask defect detection system provided in this embodiment belong to the same inventive concept as the photomask defect detection method provided in this embodiment. Therefore, the computer-readable medium and photomask defect detection system provided in this embodiment have at least all the advantages of the photomask defect detection system provided in this embodiment, and can scan and detect the graphic area 200 and the opaque area 300 at the same time, shortening the detection time and avoiding missing defects.

[0063] In summary, the above embodiments provide detailed descriptions of different configurations of the photomask defect detection method, system, and computer-readable medium. Of course, the above description is only a description of the preferred embodiments of the present invention, and is not any limitation to the scope of the present invention. The present invention includes but is not limited to the configurations listed in the above implementations. Those skilled in the art can draw inferences based on the contents of the above embodiments. Any changes and modifications made by those of ordinary skill in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A method for detecting photomask defects, characterized in that: include: Providing a photomask, the photomask comprising a graphic area and an opaque area, wherein the opaque area is arranged around the graphic area; Loading the photomask into a testing machine, selecting the type of material to be tested through the testing machine, and screening out the graphic area and the opaque area from the photomask through the testing machine; The detection parameters of the graphic area and the opaque area are set by the detection machine, including setting the sensitivity of the penetrating light of the graphic area to V1, the sensitivity of the reflected light to V2, and setting the sensitivity of the penetrating light of the opaque area to V3, and the sensitivity of the reflected light to 0, wherein V1, V2 and V3 are not equal to 0, and V3 is less than V1; Based on the set inspection parameters of the graphic area and the opaque area, the inspection light source is turned on to scan and inspect the photomask.

2. The photomask defect detection method according to claim 1, characterized in that: The material of the graphic area includes glass and molybdenum silicon deposited on the glass surface, and the material of the opaque area includes glass, molybdenum silicon deposited on the glass surface, and metal chromium deposited on the surface of molybdenum silicon.

3. The photomask defect detection method according to claim 2, characterized in that: The types of materials to be tested by the testing machine include: Through the selection mode of the material to be tested set by the detection machine, molybdenum silicide and glass are selected as the materials to be tested.

4. The photomask defect detection method according to claim 1, characterized in that: The method of screening out the graphic area and the opaque area from the photomask by using the detection machine comprises: Obtain the original coordinate file generated by the photomask during the design stage; Based on the original coordinate file, the coordinates of the diagonal lines of the graphic area are input into the detection machine to screen out multiple graphic areas, and the coordinates of the diagonal lines of the opaque area are input into the detection machine to screen out the opaque area.

5. The photomask defect detection method according to claim 1, characterized in that: The setting range of the sensitivity V1 of the penetrating light in the graphic area is 90-100, the setting range of the sensitivity V2 of the reflected light in the graphic area is 80-90, the setting range of the sensitivity V3 of the penetrating light in the opaque area is 70-80, and V3 is smaller than V1.

6. The photomask defect detection method according to claim 1, characterized in that: The sensitivity V3 of the light transmitted through the opaque area is set to 80.

7. The photomask defect detection method according to claim 1, characterized in that: The defect in the opaque area detected by the detection machine is a pinhole defect.

8. The photomask defect detection method according to claim 1, characterized in that: The length and width of defects in the opaque area captured by the detection machine are both greater than or equal to 500nm, and the length and width of defects in the graphic area captured by the detection machine are both greater than or equal to 10nm.

9. A computer-readable medium having a program stored thereon, characterized in that: include: When the program is executed, at least part of the steps in the photomask defect detection method according to any one of claims 1 to 8 are performed.

10. A photomask defect detection system, characterized in that: include: An acquisition module is used to load the photomask into a testing machine, select the type of material to be tested through the testing machine, and screen out the graphic area and the opaque area from the photomask through the testing machine; An editing module, used to set the detection parameters of the graphic area and the opaque area through the detection machine, including setting the sensitivity of the penetrating light of the graphic area to V1, the sensitivity of the reflected light to V2, and setting the sensitivity of the penetrating light of the opaque area to V3, and the sensitivity of the reflected light to 0, wherein V1, V2 and V3 are not equal to 0, and V3 is less than V1; The detection module is used to turn on the detection light source to scan and detect the photomask based on the set detection parameters of the graphic area and the opaque area.

Images