Detection method for shading band of phase shift mask plate

Abstract

The invention relates to the technical field of semiconductor integrated circuit manufacturing, in particular to a method for detecting a shading band of a phase shift mask plate. The method comprises the following steps: performing a first exposure operation on a to-be-detected phase shift mask plate to form a first exposure area; a detection structure in the detection light-transmitting part forms a B initial detection pattern through the first exposure operation; performing a second exposure operation on the to-be-detected phase shift mask plate to form a second exposure area, performing the second exposure operation on the detection structure in the detection light-transmitting area, and forming a final detection pattern B on the basis of the initial detection pattern B, the detection structure in the target shading part forms an A final detection pattern through the second exposure operation; and based on the difference between the critical dimension of the final detection pattern A and the critical dimension of the final detection pattern B, judging whether the shading film coverage area of the to-be-detected phase shift mask plate is abnormal or not.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor integrated circuit manufacturing, and in particular to a method for detecting a light-shielding band of a phase-shift mask. Background Art

[0002] In the semiconductor manufacturing process, photolithography transfers patterns to the wafer through a mask as a medium, so the quality of the pattern transfer process is closely related to the quality of the mask production.

[0003] The phase shift mask (PSM) includes a light-transmitting area and a light-shielding area, wherein the light-transmitting area includes multiple light-transmitting layers, and the light-shielding area also includes a light-shielding layer. Usually, when making a phase shift mask, the light-shielding layer completely covers the light-shielding area, so that the light-shielding area has a good light-blocking effect.

[0004] However, the reality is that when there is an abnormality in the manufacturing of the phase-shift mask shading band, the shading layer does not completely cover the shading area, that is, part of the shading area can pass light. At present, semiconductor wafer manufacturing plants cannot directly detect whether there is a problem in the phase-shift mask manufacturing process. Summary of the invention

[0005] The present application provides a method for detecting a light-shielding band of a phase-shift mask, which can solve the problem in the related art that it is difficult to detect whether there is an abnormality in the manufacturing of the light-shielding band of the phase-shift mask.

[0006] In order to solve the technical problem in the background technology, the present application provides a detection method of a phase-shift mask, wherein an exposure overlapping template portion of the phase-shift mask comprises a target light-shielding portion and a target light-transmitting portion, wherein a detection light-transmitting portion is provided in the target light-shielding portion; a plurality of identical detection structures are provided in the exposure overlapping template portion, and identical detection structures are respectively provided in the target light-transmitting portion, the target light-shielding portion and the detection light-transmitting portion;

[0007] The detection method of the phase-shift mask comprises the following steps:

[0008] The phase-shift mask to be tested is subjected to a first exposure operation to form a first exposure area; the detection structure in the detection light-transmitting portion is subjected to the first exposure operation to form a B initial detection pattern;

[0009] The phase-shift mask to be tested is subjected to a second exposure operation to form a second exposure area, the detection structure in the detection light-transmitting area is subjected to the second exposure operation to form a B final detection pattern on the basis of the B initial detection pattern, and the detection structure in the target light-shielding portion is subjected to the second exposure operation to form an A final detection pattern;

[0010] Based on the difference between the critical dimension of the A final inspection pattern and the critical dimension of the B final inspection pattern, it is determined whether the light shielding film coverage area of ​​the phase-shift mask to be inspected is abnormal.

[0011] Optionally, the step of performing a second exposure operation on the phase-shift mask to be tested to form a second exposure area includes:

[0012] Performing a second exposure operation on the phase-shift mask to be tested to form a second exposure area;

[0013] The first exposure area and the second exposure area overlap to form a first overlapping exposure area; in the first overlapping exposure area, the detection structure of the first exposure operation overlaps with the detection structure of the second exposure operation;

[0014] The detection structure in the detection light-transmitting area forms a B final detection pattern on the basis of the B initial detection pattern after the second exposure operation, and the detection structure in the target light-shielding portion forms an A final detection pattern after the second exposure operation.

[0015] Optionally, the first exposure area includes a first light-shielding area formed by a target light-shielding portion of the phase-shift mask and a first light-transmitting area formed by the target light-transmitting portion in the first exposure operation;

[0016] The second exposure area includes a second light-shielding area formed by the target light-shielding portion of the phase-shift mask and a second light-transmitting area formed by the target light-transmitting portion in the second exposure operation;

[0017] In the first overlapping exposure area, the second light-transmitting area in the second exposure operation overlaps with the first light-shielding area in the first exposure operation, and the first light-transmitting area in the first exposure operation overlaps with the second light-shielding area in the second exposure operation.

[0018] Optionally, the phase-shift mask to be measured comprises a first light-transmitting layer, a second light-transmitting layer and a light-shielding layer stacked in sequence from bottom to top;

[0019] The second light-transmitting layer at the position of the target light-transmitting portion is not covered with a light-shielding layer, and the second light-transmitting layer at the position of the target light-shielding portion is covered with a light-shielding layer.

[0020] Optionally, the first light-transmitting layer is made of quartz.

[0021] Optionally, the second light-transmitting layer is made of molybdenum silicide with a light transmittance of 6% to 7%.

[0022] Optionally, the step of judging whether the light shielding film coverage area of ​​the phase-shift mask to be tested is abnormal based on the difference between the critical size of the final test pattern A and the critical size of the final test pattern B comprises:

[0023] Measuring the critical dimensions of the final inspection pattern A and the critical dimensions of the final inspection pattern B;

[0024] When the critical dimension of the final detection pattern A is consistent with the critical dimension of the final detection pattern B, it is determined that the phase-shift mask to be tested is abnormal;

[0025] When the critical dimension of the final inspection pattern A is inconsistent with the critical dimension of the final inspection pattern B, it is determined that the phase-shift mask to be tested is normal.

[0026] Optionally, when the critical dimension of the final detection pattern A is inconsistent with the critical dimension of the final detection pattern B, the step of determining that the phase-shift mask to be tested is normal includes:

[0027] When the critical dimension of the A final detection pattern is greater than the critical dimension of the B final detection pattern, it is determined that the phase-shift mask to be tested is normal.

[0028] The technical solution of the present application includes at least the following advantages: the present application sets a plurality of identical detection structures in the exposure overlapping template portion of the phase-shift mask to be tested, that is, the target light-transmitting portion, the target light-shielding portion and the detection light-transmitting portion are all provided with detection structures, so that the above two exposure areas overlap after the first exposure area and the second exposure area are formed. Among them, the detection structure in the detection light-transmitting portion undergoes two exposures, the first exposure and the second exposure, and the exposure experienced by the detection structure in the target light-shielding portion is determined by whether the target light-shielding portion is normal. Therefore, it is possible to judge whether the light-shielding film coverage area of ​​the phase-shift mask to be tested is abnormal based on the difference in the key size of the final detection pattern A formed by the exposure of the detection structure of the target light-shielding portion and the key size of the final detection pattern B formed by the exposure of the detection structure of the detection light-transmitting portion, which is conducive to detecting abnormal phase-shift masks during the wafer manufacturing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] 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.

[0030] Figure 1 A schematic diagram of a top view structure of a phase-shift mask provided in an embodiment of the present application is shown;

[0031] Figure 2 Shows Figure 1 A schematic diagram of the enlarged structure of the target shading portion;

[0032] Figure 3 Shows Figure 1 A schematic cross-sectional view of the light shielding portion of the target;

[0033] Figure 4 A schematic diagram of a cross-sectional structure of an abnormal phase-shift mask is shown;

[0034] Figure 5 A schematic diagram of a process flow of a method for detecting a light-shielding band of a phase-shift mask provided in an embodiment of the present application is shown;

[0035] Figure 6 A schematic diagram of a first exposure area formed on the photoresist layer after step S1 is completed is shown;

[0036] Figure 7 A schematic diagram of a second exposure area formed on the photoresist layer after step S2 is completed is shown. DETAILED DESCRIPTION

[0037] 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.

[0038] 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 the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0039] 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.

[0040] 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.

[0041] Figure 1 A schematic diagram of a top view of a phase shift mask provided in an embodiment of the present application is shown. Figure 1 As can be seen in the figure, the phase-shift mask 100 includes a main template portion 101 located in the middle area and an exposure overlap template portion 102 located at the periphery of the main template portion 101, wherein the main template portion 101 is a light-transmitting area. The exposure overlap template portion 102 is provided with a plurality of identical detection structures 103, and the detection structures 103 are symmetrically distributed in the exposure overlap template portion 102.

[0042] The exposure overlap template portion 102 includes a target light shielding portion 120 and a target light transmitting portion 110, wherein the target light shielding portion 120 is provided with a detection light transmitting portion 130; Figure 1 It can be seen that the target light-transmitting portion 110 , the target light-shielding portion 120 and the detection light-transmitting portion 130 are all provided with the detection structure 103 .

[0043] Figure 2 Shows Figure 1 The enlarged structural diagram of the target shading part in the Figure 2 It can be seen that the target light shielding portion 120 includes a light shielding belt body 121 and a detection light transmitting portion 130 , and both the light shielding belt body 121 and the detection light transmitting portion 130 in the target light shielding portion 120 are provided with the detection structure 103 .

[0044] Figure 3 Shows Figure 1 Schematic diagram of the cross-sectional structure of the target shading part, from Figure 3 As can be seen from the figure, the phase-shift mask 100 includes a first light-transmitting layer 210, a second light-transmitting layer 220 and a light-shielding layer 230 stacked in sequence from bottom to top.

[0045] For the target light shielding portion 120, it is covered with Figure 3 The light shielding layer 230 is shown, and a window is opened in the light shielding layer 230 in the target light shielding part 120, so that the second light-transmitting layer 220 under the light shielding layer 230 is exposed from the window position. The light shielding belt body 121 in the target light shielding part 120 and the detection light-transmitting part 130 are both provided with the detection structure 103.

[0046] When the target light shielding portion of the phase shift mask is normal, the window position is the detection light-transmitting portion 130 of the target light shielding portion 120, and the light shielding belt body 121 of the target light shielding portion 120 is completely covered with Figure 3As shown in the light shielding layer 230 , the detection structure 103 of the light-transmitting portion 130 is exposed, and the detection structure of the light shielding belt body 121 is covered by the light shielding layer 230 .

[0047] Figure 4 The schematic diagram of the cross-sectional structure of the abnormal phase-shift mask is shown. Figure 4 As can be seen from the figure, the phase-shift mask includes a first light-transmitting layer 210, a second light-transmitting layer 220 and a light-shielding layer 230 stacked in sequence from bottom to top.

[0048] For the abnormal phase-shift mask, in addition to the window formed in the light-shielding layer 230 at the detection light-transmitting portion 130 of the target light-shielding portion 120 so that the second light-transmitting layer 220 is exposed, the light-shielding belt body 121 also forms an abnormal window area 131, and the second light-transmitting layer 220 at the abnormal window area 131 is also exposed. Thus, the detection structure of the light-shielding belt body 121 and the detection structure of the detection light-transmitting portion 130 are both exposed.

[0049] Exemplarily, the first light-transmitting layer 510 may be made of quartz or other materials, and the second light-transmitting layer 520 may be molybdenum silicide (MoSi) with a light transmittance of 6%.

[0050] For the phase shift mask to be tested in the embodiment of the present application, Figure 3 The normal phase shift mask shown is still Figure 4 The abnormal phase-shift mask shown is unknown to be tested and needs to be judged through subsequent steps.

[0051] Figure 5 The schematic diagram of the detection method of the light shielding band of the phase shift mask provided by an embodiment of the present application is shown. Figure 5 It can be seen that the detection method of the phase-shift mask shading band includes the following steps:

[0052] Step S1: performing a first exposure operation on the phase-shift mask to be tested to form a first exposure area.

[0053] Figure 6 FIG. 3 is a schematic diagram showing a first exposure area formed on the photoresist layer after step S1 is completed. After step S1 is completed, the phase shift mask to be tested forms a first exposure area 310. Figure 3 or Figure 4 After the first exposure operation, the detection structure in the detection light-transmitting portion 130 will form an initial detection pattern B on the photoresist layer of the wafer after development. Figure 3 The normal target shading portion 120 shown in the figure has the shading tape body 121 completely covered by the shading layer 230, that is, the detection structure of the shading tape body 121 is covered by the shading layer 230, so that the first exposure operation will not expose the detection structure at the position of the shading tape body 121 to the photoresist layer.

[0054] Continue to refer to Figure 6 , after the first exposure, Figures 1 to 4 The main template portion 101 of the phase shift mask 100 is exposed to form a main exposure area 311 of the first exposure area 310, and the exposure overlap template portion 102 is exposed to form an exposure overlap area 312 of the first exposure area 310. The exposure overlap area 312 is located at the periphery of the main exposure area 311, and the exposure overlap area 312 overlaps with other exposure areas formed in the subsequent exposure process. The exposure overlap area 312 includes a first light shielding area 313 formed by the target light shielding portion 120, and a first light transmission area 314 formed by the target light transmission portion 110. The first light shielding area 313 includes a detection light transmission area 315 formed by the detection light transmission portion 130, and a light shielding belt body area 316 formed by the light shielding belt body 121.

[0055] Step S2: performing a second exposure operation on the phase-shift mask to be tested to form a second exposure area, the detection structure in the detection light-transmitting area undergoes the second exposure operation to form a B final detection pattern on the basis of the B initial detection pattern, and the detection structure in the target light-shielding portion undergoes the second exposure operation to form an A final detection pattern.

[0056] Figure 7 FIG. 2 shows a schematic diagram of a second exposure area formed on the photoresist layer after step S2 is completed. For example, the phase-shift mask to be tested can be shifted rightward from the position of the first exposure area 310 according to a specific step length, so that after step S2 is completed, the phase-shift mask to be tested forms a second exposure area 320. For example, the first exposure area 310 and the second exposure area 320 partially overlap to form a first overlapping exposure area 330, and the first overlapping exposure area 330 is Figure 6 The right portion of the exposure overlap region 312 is shown in FIG.

[0057] from Figure 7 It can be seen that after the second exposure, Figures 1 to 4 The main template portion 101 of the phase shift mask 100 is exposed to form a main exposure area 321 of the second exposure area 320, and the exposure overlap template portion 102 is exposed to form an exposure overlap area of ​​the second exposure area 320, the exposure overlap area is located at the periphery of the main exposure area 321, and the second exposure area 320 partially overlaps with the first exposure area 310 to form a first overlap exposure area 330. The first overlap exposure area 330 includes a second light shielding area 323 formed by a target light shielding portion and a second light transparent area 322 formed by a target light transparent portion. In the first overlap exposure area 330, the second light transparent area 322 in the second exposure operation overlaps with the first light shielding area 313 in the first exposure operation, and the first light transparent area 314 in the first exposure operation overlaps with the second light shielding area 323 in the second exposure operation.

[0058] After the phase-shift mask to be tested is shifted, for the second exposure operation, Figure 2 and Figure 3 The detection structure 103 in the detection light-transmitting portion 130 of the phase-shift mask to be tested is subjected to the second exposure operation to form a B final detection pattern on the basis of the B initial detection pattern, and the detection structure 103 in the target light-shielding portion 120 is subjected to the second exposure operation to form an A final detection pattern, that is, the detection structure 103 in the target light-shielding portion 120 has only undergone one exposure, and the detection structure 103 in the detection light-transmitting portion 130 has undergone two exposures.

[0059] for Figure 4 In the phase-shift mask to be tested shown, the detection structure 103 in the target shading portion 120 is not blocked by the shading tape body 121 due to the existence of the abnormal window area 131, so that the detection structure 103 in the target shading portion 120 and the detection structure 103 in the detection light-transmitting portion 130 are both exposed twice.

[0060] Step S3: Based on the difference between the critical dimension of the final inspection pattern A and the critical dimension of the final inspection pattern B, it is determined whether the light shielding film coverage area of ​​the phase-shift mask to be inspected is abnormal.

[0061] Exemplarily, step S3 includes the following steps:

[0062] Step S31: measuring the critical dimensions of the final inspection pattern A and the critical dimensions of the final inspection pattern B.

[0063] Step S32: When the critical dimension of the final detection pattern A is consistent with the critical dimension of the final detection pattern B, it is determined that the phase-shift mask to be tested is abnormal.

[0064] Step S33: When the critical dimension of the final inspection pattern A is inconsistent with the critical dimension of the final inspection pattern B, it is determined that the phase-shift mask to be tested is normal.

[0065] Exemplarily, when the critical dimension of the final detection pattern A is greater than the critical dimension of the final detection pattern B, it is determined that the phase-shift mask to be tested is normal. Since when the phase-shift mask to be tested is normal, the detection structure 103 in the target light-transmitting portion 130 undergoes two exposures, while the detection structure 103 in the target light-shielding portion 120 undergoes only one exposure, the critical dimension of the final detection pattern A obtained by the detection structure 103 in the target light-shielding portion 120 after one exposure is greater than the critical dimension of the final detection pattern B obtained by the detection structure 103 in the target light-transmitting portion 130 after two exposures.

[0066] The present application sets a plurality of identical detection structures in the exposure overlapping template portion of the phase-shift mask to be tested, that is, the target light-transmitting portion, the target light-shielding portion and the detection light-transmitting portion are all provided with detection structures, so that the above two exposure areas overlap after forming the first exposure area and the second exposure area. Among them, the detection structure in the detection light-transmitting portion undergoes two exposures, the first exposure and the second exposure, and the exposure experienced by the detection structure in the target light-shielding portion is determined by whether the target light-shielding portion is normal. Therefore, according to the difference in the key size of the final detection pattern A formed by the exposure of the detection structure of the target light-shielding portion and the key size of the final detection pattern B formed by the exposure of the detection structure of the detection light-transmitting portion, it can be judged whether the light-shielding film coverage area of ​​the phase-shift mask to be tested is abnormal, which is conducive to detecting abnormal phase-shift masks during the wafer manufacturing process.

[0067] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection created by this application.

Claims

1. A method for detecting a phase shift mask, characterized in that: The exposure overlapping template portion of the phase shift mask comprises a target light shielding portion and a target light transmitting portion, wherein the target light shielding portion is provided with a detection light transmitting portion; the exposure overlapping template portion is provided with a plurality of identical detection structures, wherein the target light transmitting portion, the target light shielding portion and the detection light transmitting portion are respectively provided with identical detection structures; The detection method of the phase-shift mask comprises the following steps: The phase-shift mask to be tested is subjected to a first exposure operation to form a first exposure area; the detection structure in the detection light-transmitting portion is subjected to the first exposure operation to form a B initial detection pattern; The phase-shift mask to be tested is subjected to a second exposure operation to form a second exposure area, the detection structure in the detection light-transmitting area is subjected to the second exposure operation to form a B final detection pattern on the basis of the B initial detection pattern, and the detection structure in the target light-shielding portion is subjected to the second exposure operation to form an A final detection pattern; Based on the difference between the critical dimension of the A final inspection pattern and the critical dimension of the B final inspection pattern, it is determined whether the light shielding film coverage area of ​​the phase-shift mask to be inspected is abnormal.

2. The method for detecting a phase-shift mask according to claim 1, wherein: The step of performing a second exposure operation on the phase-shift mask to be tested to form a second exposure area comprises: Performing a second exposure operation on the phase-shift mask to be tested to form a second exposure area; The first exposure area and the second exposure area overlap to form a first overlapping exposure area; in the first overlapping exposure area, the detection structure of the first exposure operation overlaps with the detection structure of the second exposure operation; The detection structure in the detection light-transmitting area forms a B final detection pattern on the basis of the B initial detection pattern after the second exposure operation, and the detection structure in the target light-shielding portion forms an A final detection pattern after the second exposure operation.

3. The method for detecting a phase-shift mask according to claim 2, wherein: The first exposure area includes a first light-shielding area formed by a target light-shielding portion of the phase-shift mask and a first light-transmitting area formed by the target light-transmitting portion in the first exposure operation; The second exposure area includes a second light-shielding area formed by the target light-shielding portion of the phase-shift mask and a second light-transmitting area formed by the target light-transmitting portion in the second exposure operation; In the first overlapping exposure area, the second light-transmitting area in the second exposure operation overlaps with the first light-shielding area in the first exposure operation, and the first light-transmitting area in the first exposure operation overlaps with the second light-shielding area in the second exposure operation.

4. The method for detecting a phase-shift mask according to claim 1, wherein: The phase-shift mask to be tested comprises a first light-transmitting layer, a second light-transmitting layer and a light-shielding layer stacked in sequence from bottom to top; The second light-transmitting layer at the position of the target light-transmitting portion is not covered with a light-shielding layer, and the second light-transmitting layer at the position of the target light-shielding portion is covered with a light-shielding layer.

5. The method for detecting a phase-shift mask according to claim 4, characterized in that: The first light-transmitting layer is made of quartz.

6. The method for detecting a phase-shift mask according to claim 4, wherein: The second light-transmitting layer is made of molybdenum silicide with a light transmittance of 6% to 7%.

7. The method for detecting a phase-shift mask according to claim 4, wherein: The step of judging whether the light shielding film coverage area of ​​the phase shift mask to be tested is abnormal based on the difference between the critical size of the final detection pattern A and the critical size of the final detection pattern B comprises: Measuring the critical dimensions of the final inspection pattern A and the critical dimensions of the final inspection pattern B; When the critical dimension of the final detection pattern A is consistent with the critical dimension of the final detection pattern B, it is determined that the phase-shift mask to be tested is abnormal; When the critical dimension of the final inspection pattern A is inconsistent with the critical dimension of the final inspection pattern B, it is determined that the phase-shift mask to be tested is normal.

8. The method for detecting the light-shielding band of the phase-shift mask according to claim 7, characterized in that: When the critical dimension of the final detection pattern A is inconsistent with the critical dimension of the final detection pattern B, the step of determining that the phase-shift mask to be tested is normal includes: When the critical dimension of the A final detection pattern is greater than the critical dimension of the B final detection pattern, it is determined that the phase-shift mask to be tested is normal.

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