Mask and mask-based detection method

Abstract

The present application relates to the technical field of integrated circuit manufacturing, and provides a mask and a detection method based on the mask, wherein the mask pattern on the mask comprises an exposure resolution detection pattern and a overlay accuracy detection pattern, and the overlay accuracy detection pattern comprises a first overlay sub-pattern and a second overlay sub-pattern. The mask can be rotated by a preset angle from a first placement state to a second placement state; the second overlay sub-pattern formed by exposure in the two placement states can be combined with the first overlay sub-pattern to form an overlay accuracy detection pattern suitable for detecting overlay accuracy; meanwhile, the exposure resolution detection pattern formed by exposure is suitable for detecting the exposure resolution of a wafer. The mask of the present application can form the overlay accuracy detection pattern and the exposure resolution detection pattern on the wafer by rotating a single mask, so as to detect the exposure resolution of the wafer and the overlay accuracy of twice exposure, and effectively simplify the detection process.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit manufacturing technology, and in particular to a photomask and a photomask-based inspection method. Background Technology

[0002] In the field of integrated circuit photolithography, overlay error and exposure resolution are crucial performance indicators during wafer processing. Related technologies require multiple photomasks to create various exposure patterns on two layers of the wafer. A portion of these patterns is used to determine the positional offset between the current and previous layers, thus obtaining the overlay error. The remaining portion of the patterns determines the exposure resolution. This process involves repeatedly changing photomasks and aligning the optical path and patterns, making it cumbersome and complex. Summary of the Invention

[0003] This invention aims to solve the technical problems existing in related technologies. To this end, this invention proposes a photomask to solve the problem that currently, when checking overlay accuracy and exposure resolution, multiple photomasks are required, and photomasks need to be repeatedly replaced to complete the alignment of the optical path and pattern, resulting in a cumbersome and complex process.

[0004] The present invention also proposes a detection method based on a mask.

[0005] According to the mask provided in the embodiment of the present invention, the mask pattern on the mask includes an exposure resolution detection pattern and an overlay accuracy detection pattern, the exposure resolution detection pattern and the overlay accuracy detection pattern are spatially separated on the mask, and the overlay accuracy detection pattern includes a first set of engraving patterns and a second set of engraving patterns; The mask can be rotated by a preset angle from a first position state to a second placement state; in the first placement state, a first exposure pattern is formed on the wafer based on the mask pattern; in the second placement state, a second exposure pattern is formed on the wafer based on the mask pattern; both the first exposure pattern and the second exposure pattern include a first set of etched patterns corresponding to the first set of etched patterns, a second set of etched patterns corresponding to the second set of etched patterns, and an exposure resolution detection pattern corresponding to the exposure resolution detection pattern; Wherein, the first set of engraving patterns in the first exposure pattern is paired with the second set of engraving patterns in the second exposure pattern, and / or the second set of engraving patterns in the first exposure pattern is paired with the first set of engraving patterns in the second exposure pattern to form an overlay accuracy detection pattern suitable for detecting overlay accuracy; the exposure resolution detection pattern in the first exposure pattern and / or the second exposure pattern is suitable for detecting the exposure resolution of the wafer; the overlay accuracy detection pattern and the exposure resolution detection pattern do not interfere with each other.

[0006] According to one embodiment of the present invention, one of the first set of engraved patterns and the second set of engraved patterns is a main scale pattern and the other is a vernier scale pattern; in the first exposure pattern and the second exposure pattern, the main scale pattern corresponding to the main scale pattern and the vernier scale pattern corresponding to the vernier scale pattern together constitute a vernier caliper pattern.

[0007] According to one embodiment of the present invention, the preset angle is an integer multiple of 90°; The main scale graphic includes a first main scale and a second main scale, wherein the extension direction of the first main scale and the extension direction of the second main scale are perpendicular to each other. The vernier scale graphic includes: a first vernier scale and a second vernier scale, wherein the extension direction of the first vernier scale and the extension direction of the second vernier scale are perpendicular to each other; The first vernier scale pattern in the second exposure pattern and the first main scale pattern in the first exposure pattern constitute the vernier caliper pattern; the second vernier scale pattern in the second exposure pattern and the second main scale pattern in the first exposure pattern constitute the vernier caliper pattern.

[0008] According to one embodiment of the present invention, there are multiple sets of the first set of engraving patterns, the second set of engraving patterns, and the exposure resolution detection patterns; The second set of engraving patterns in the second exposure pattern and the first set of engraving patterns in the first exposure pattern can be combined to form multiple engraving accuracy detection patterns; multiple exposure resolution detection patterns are formed in the first exposure pattern and the second exposure pattern; The plurality of overlay accuracy detection patterns are centrally symmetrically distributed with respect to the center of the wafer; and / or, the plurality of exposure resolution detection patterns are centrally symmetrically distributed with respect to the center of the wafer.

[0009] According to one embodiment of the present invention, the mask includes four distribution areas and a central area, the rotation center of the mask coincides with the geometric center of the central area; the four distribution areas surround the outside of the central area, and the four distribution areas are centrally symmetrically distributed with respect to the rotation center of the mask; The central area includes the first set of engraved patterns, the second set of engraved patterns, and the exposure resolution detection pattern. One of two adjacent distribution areas is provided with the first set of engraved patterns, and the other of two adjacent distribution areas is provided with the second set of engraved patterns; at least one of the two adjacent distribution areas is provided with the exposure resolution detection pattern.

[0010] According to one embodiment of the present invention, the mask pattern further includes: A first target pattern and a second target pattern, wherein the first target pattern and the second target pattern satisfy a preset offset relationship relative to the rotation center of the mask, and the first target pattern formed by the first target pattern in the second placement state is aligned with the second target pattern formed by the second target pattern in the first placement state.

[0011] According to one embodiment of the present invention, there are multiple first target patterns and multiple second target patterns, which are arranged alternately along the rotation direction of the mask. The angles formed by the lines connecting the geometric centers of adjacent first target patterns and second target patterns to the rotation center of the mask are equal to the preset angle.

[0012] According to one embodiment of the present invention, the exposure resolution detection pattern includes at least one of the following patterns: The first detection block includes multiple line graphics arranged parallel to each other along a first direction and extending along a second direction; The second detection block includes multiple line graphics arranged parallel to each other along a second direction and extending along a first direction; the first direction and the second direction are perpendicular. The third detection block consists of multiple square patterns arranged in an array.

[0013] The detection method based on the mask described in any one of the above claims, provided by embodiments of the present invention, includes: The photomask is placed in the photolithography machine in the first placement state, and the first exposure pattern is formed by exposing the first photolithography layer on the wafer. The photomask is rotated to the second placement state, and the second exposure pattern is formed by exposing the second photolithography layer of the wafer. Based on the first exposure pattern and the second exposure pattern, the overlay accuracy and exposure resolution are determined.

[0014] According to an embodiment of the present invention, there are multiple sets of first engraving patterns, multiple sets of second engraving patterns, and multiple exposure resolution detection patterns; the second set of engraving patterns in the second exposure pattern and the first set of engraving patterns in the first exposure pattern can be combined to form multiple engraving accuracy detection patterns with different positions; multiple exposure resolution detection patterns with different positions are formed in the first exposure pattern and the second exposure pattern; The exposure uniformity of the wafer is determined based on multiple overlay accuracy detection patterns and multiple exposure analysis detection patterns.

[0015] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects: The photomask of this invention, when exposing a wafer on a lithography machine, can rotate to form a first exposure pattern and a second exposure pattern on the first and second lithography layers of the wafer, respectively. By setting non-interfering exposure resolution detection patterns and overlay accuracy detection patterns on the photomask, the overlay accuracy detection pattern includes a first set of etched patterns and a second set of etched patterns spaced apart along the rotation direction. This allows the first set of etched patterns corresponding to the first overlay pattern on the first exposure pattern and the second set of etched patterns corresponding to the second overlay pattern on the second exposure pattern to combine into an overlay accuracy detection pattern suitable for detecting overlay accuracy. The exposure resolution detection pattern can form an exposure resolution detection pattern that does not overlap or interfere with the overlay accuracy detection pattern, thus facilitating the detection of the wafer's exposure resolution and the overlay accuracy of the two exposures. The entire detection process only requires rotating a single photomask, eliminating the need to repeatedly change photomasks on the lithography machine, effectively simplifying the detection process.

[0016] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention and are not considered as limitations on this application. Moreover, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0018] Figure 1 This is a schematic structural diagram of the mask provided in the embodiment of the present invention in the first placement state.

[0019] Figure 2 This is a schematic structural diagram of the mask provided in the second placement state according to an embodiment of the present invention.

[0020] Figure 3 This is a schematic structural diagram of the main scale graphic provided in the embodiment of the present invention.

[0021] Figure 4 This is a schematic structural diagram of the vernier scale graphic provided in an embodiment of the present invention.

[0022] Figure 5 This is a schematic structural diagram showing the main scale pattern and the vernier scale pattern arranged side by side, provided in an embodiment of the present invention.

[0023] Figure 6 This is a schematic structural diagram of the first target pattern provided in an embodiment of the present invention.

[0024] Figure 7 This is one of the schematic structural diagrams of the second target pattern provided in the embodiments of the present invention.

[0025] Figure 8 This is a schematic structural diagram showing the alignment of the first target pattern and the second target pattern provided in an embodiment of the present invention.

[0026] Figure 9 This is a second schematic structural diagram of the second target pattern provided in the embodiments of the present invention.

[0027] Figure 10 This is a schematic structural diagram of the exposure resolution detection pattern provided in an embodiment of the present invention.

[0028] Figure 11 This is a schematic structural diagram of the first combined graphic provided in the embodiments of the present invention.

[0029] Figure 12 This is a schematic structural diagram of the second combined graphic provided in the embodiments of the present invention.

[0030] Figure 13 This is a schematic structural diagram of the central area provided in an embodiment of the present invention.

[0031] Figure 14 This is a schematic diagram of a pattern formed by superimposing a first exposure pattern and a second exposure pattern on a wafer, as provided in an embodiment of the present invention.

[0032] Figure 15 This is one of the schematic structural diagrams of the detection pattern group on the wafer provided in the embodiments of the present invention.

[0033] Figure 16 This is the second schematic structural diagram of the detection pattern group on the wafer provided in the embodiments of the present invention.

[0034] Figure 17 This is a flowchart of a mask-based detection method provided in an embodiment of the present invention.

[0035] Figure label: 1. Photomask; 11. Mask pattern; 111. Main scale pattern; 1111. Main scale design; 1112. First main scale; 11121. First main scale design; 1113. Second main scale; 11131. Second main scale design; 112. Vernier scale pattern; 1121. Vernier scale design; 1122. First vernier scale; 11221. First vernier scale design; 1123. Second vernier scale; 11231. Second vernier scale design; 113. First target graphic; 1131. First target pattern; 114. Second target graphic; 1141. Second target pattern; 115. Exposure resolution detection pattern; 1151. Exposure resolution detection design; 1152. First detection block; 1153. Second detection block; 1154. Third detection block; 12. Distribution area; 121. First combination of shapes; 122. Second combination of shapes; 13. Central area; 131. Third combination of shapes; 132. Fourth combination of shapes; 133. Fifth combination of shapes; 2. Detect pattern group. Detailed Implementation

[0036] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0037] The specific terms used in this specification are for illustrative purposes only and are not intended to limit the illustrated embodiments. For example, expressions such as "same" and "identical" not only indicate a strictly identical state, but also indicate a state with tolerances or differences in the degree of functionality. For example, expressions indicating relative or absolute arrangement such as "in a certain direction," "along a certain direction," "side by side," "perpendicular," "centered on," "concentric," or "coaxial" not only strictly indicate such an arrangement, but also indicate a state of relative displacement by tolerances or angles or distances with the same degree of functionality.

[0038] The terms “center,” “longitudinal,” “lateral,” “length,” “width,” “thickness,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0039] Furthermore, features specified as "first" or "second" may explicitly or implicitly include one or more of those features. In the description of this invention, unless otherwise stated, "multiple" means two or more. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly specified. In the description of the embodiments of this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, B1 and / or B2 can represent: B1 existing alone, B1 and B2 existing simultaneously, and B2 existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0040] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0041] The following is combined Figures 1 to 16 The mask of the present invention is described.

[0042] It should be noted that, for ease of distinction, in the description of this invention, features with the word "graphic" usually refer to the graphic structure on the mask 1, while features with the word "pattern" are the pattern features formed by the lithography machine exposing the wafer based on the mask 1.

[0043] like Figure 1 , Figure 3 , Figure 4 and Figure 5As shown, the mask pattern 11 on the mask 1 includes an exposure resolution detection pattern 115 and an overlay accuracy detection pattern. The exposure resolution detection pattern 115 and the overlay accuracy detection pattern are spatially separated on the mask 1. The overlay accuracy detection pattern includes a first set of overlay patterns and a second set of overlay patterns.

[0044] The photomask 1 has a first placement state and a second placement state, the second placement state being rotated by a preset angle relative to the first placement state; in the first placement state, the photomask 1 forms a first exposure pattern on the wafer based on the mask pattern 11, and in the second placement state, the photomask 1 forms a second exposure pattern on the wafer based on the mask pattern 11; both the first exposure pattern and the second exposure pattern include a first set of etched patterns corresponding to the first set of etched patterns, a second set of etched patterns corresponding to the second set of etched patterns, and an exposure resolution detection pattern 1151 corresponding to the exposure resolution detection pattern 115.

[0045] The first set of engraving patterns in the first exposure pattern is paired with the second set of engraving patterns in the second exposure pattern, and / or the second set of engraving patterns in the second exposure pattern is paired with the first set of engraving patterns in the first exposure pattern to form an overlay accuracy detection pattern suitable for detecting overlay accuracy; the exposure resolution detection pattern 1151 in the first exposure pattern and / or the second exposure pattern is suitable for detecting the exposure resolution of the wafer.

[0046] The exposure resolution detection pattern 115 and the overlay accuracy detection pattern are spatially separated on the mask 1; the overlay accuracy detection pattern and the exposure resolution detection pattern 1151 do not interfere with each other.

[0047] In this embodiment, the mask 1 includes a light-transmitting portion and a light-shielding portion. A specific mask pattern 11 is formed by designing the shapes of the light-transmitting portion and the light-shielding portion. For example, the mask 1 can be a bright field mask. Specifically, the portion of the mask 1 corresponding to the mask pattern 11 adopts a light-transmitting structure, and the remaining portion adopts a light-shielding structure, so that the light path can pass through the mask pattern 11 to illuminate the photoresist coating on the wafer surface and expose to form a specific pattern. Alternatively, the mask 1 can be a dark field mask. Specifically, the portion of the mask 1 corresponding to the mask pattern 11 adopts a light-shielding structure, and the remaining portion adopts a light-transmitting structure.

[0048] The first set of etching patterns and the second set of etching patterns on the mask 1 can be set at intervals along the rotation direction of the mask 1, so that the mask 1 can form different exposure patterns in the front and back photolithography layers on the wafer by switching between the first placement state and the second placement state, and detect overlay error based on the two exposure patterns.

[0049] In practical applications, the mask 1 of this embodiment can be rotatably disposed on the optical path of the lithography machine so as to switch between the first placement state and the second placement state by rotation.

[0050] When exposing the first photolithography layer on the wafer, mask 1 can be rotated to the first placement state (e.g., Figure 1 As shown), so as to expose on the first photolithography layer to form a first exposure pattern. It is understood that the first exposure pattern includes a first set of engraving patterns corresponding to the first set of engraving patterns and a second set of engraving patterns corresponding to the second set of engraving patterns.

[0051] When exposing the second photolithographic layer on the wafer, mask 1 can be rotated to the second placement state (e.g., Figure 2 As shown), so as to expose on the second photolithography layer to form a second exposure pattern. It can be understood that, similar to the first exposure pattern, the second exposure pattern includes a first set of engraved patterns corresponding to the first set of engraved patterns and a second set of engraved patterns corresponding to the second set of engraved patterns, only the positions of each pattern are different.

[0052] By reasonably setting the relative positions of the first set of engraving patterns and the second set of engraving patterns on the mask 1, the first set of engraving patterns in the second placement state and the second set of engraving patterns in the first placement state can be combined to form an overlay accuracy detection pattern suitable for detecting overlay accuracy.

[0053] Specifically, when the overprinting error is zero, the second set of engraved patterns in the second placement state and the first set of engraved patterns in the first placement state can form a standard overprinting accuracy detection pattern; however, when the overprinting error is not zero, the relative positions of the first set of engraved patterns and the second set of engraved patterns in the same overprinting accuracy detection pattern will be offset relative to the standard overprinting accuracy detection pattern, and the overprinting error can be determined by calculating this offset.

[0054] In addition, it is understood that in actual operation, the first exposure pattern also includes the second set of engraving patterns corresponding to the second set of engraving patterns in the first placement state, and the second exposure pattern also includes the first set of engraving patterns corresponding to the first set of engraving patterns in the second placement state; therefore, the second set of engraving patterns of the first exposure pattern can also be combined with the first set of engraving patterns of the second exposure pattern to form an overlay accuracy detection pattern suitable for detecting overlay accuracy.

[0055] In other words, as long as one of the first set of engraving patterns and the second set of engraving patterns can be combined to form an overprinting accuracy detection pattern, it can be used to determine the overprinting error.

[0056] Meanwhile, by setting an exposure resolution detection pattern 115 on the mask 1, the lithography machine can form an exposure resolution detection pattern 1151 in the lithography layer when exposing the lithography layer on the wafer through the mask 1. The exposure resolution detection pattern 1151 can be used to detect the exposure resolution of the wafer.

[0057] In addition, it is understandable that by reasonably setting the positions of the exposure resolution detection pattern 115 and the overlay accuracy detection pattern on the mask 1, the two are spatially separated. In the first and second placement states, the orthographic projections of the exposure resolution detection pattern 115 and the overlay accuracy detection pattern on the wafer surface will not overlap, so that the exposure resolution detection pattern 1151 and the overlay accuracy detection pattern formed by the two exposures will not interfere with each other, so that they can be used to detect the exposure resolution of the wafer and the overlay accuracy of the two exposures respectively.

[0058] As can be seen from the above, when the photomask 1 of the present invention exposes the wafer on the lithography machine, it can rotate to form a first exposure pattern and a second exposure pattern on the first lithography layer and the second lithography layer on the wafer, respectively. By setting an exposure resolution detection pattern 115 and an overlay accuracy detection pattern that do not interfere with each other on the photomask 1, the overlay accuracy detection pattern includes a first set of etched patterns and a second set of etched patterns that are spaced apart along the rotation direction, so that the first set of etched patterns corresponding to the first overlay pattern on the first exposure pattern and the second set of etched patterns corresponding to the second overlay pattern on the second exposure pattern can be combined to form an overlay accuracy detection pattern suitable for detecting overlay accuracy. The exposure resolution detection pattern 115 can form an exposure resolution detection pattern 1151 that does not overlap or interfere with the overlay accuracy detection pattern, so as to detect the exposure resolution of the wafer and the overlay accuracy of the two exposures. The entire detection process only requires rotating a single photomask 1, without having to repeatedly change the photomask on the lithography machine, which effectively simplifies the detection process.

[0059] like Figure 1 , Figure 3 , Figure 4 and Figure 5 As shown, in the first set of engraved patterns and the second set of engraved patterns, one is the main scale pattern 111 and the other is the vernier scale pattern 112; in the first exposure pattern and the second exposure pattern, the main scale pattern 1111 corresponding to the main scale pattern 111 and the vernier scale pattern 1121 corresponding to the vernier scale pattern 112 together constitute the vernier caliper pattern.

[0060] The main scale pattern 111 and the vernier scale pattern 112 on the mask 1 can be set at intervals along the rotation direction of the mask 1, so that the mask 1 can form different exposure patterns in the front and back photolithography layers on the wafer by switching between the first placement state and the second placement state, and detect overlay error based on the two exposure patterns.

[0061] Specifically, when exposing the first photolithography layer on the wafer, the mask 1 can be rotated to the first placement state (e.g., Figure 1 As shown), so as to expose on the first photolithography layer to form a first exposure pattern. It can be understood that the first exposure pattern includes a main scale pattern 1111 corresponding to the main scale pattern 111 and a vernier scale pattern 1121 corresponding to the vernier scale pattern 112.

[0062] When exposing the second photolithographic layer on the wafer, mask 1 can be rotated to the second placement state (e.g., Figure 2 As shown), so as to expose on the second photolithography layer to form a second exposure pattern. It can be understood that, similar to the first exposure pattern, the second exposure pattern includes a main scale pattern 1111 corresponding to the main scale pattern 111 and a vernier scale pattern 1121 corresponding to the vernier scale pattern 112, only the positions of each pattern are different.

[0063] By reasonably setting the relative positions of the main scale pattern 111 and the vernier scale pattern 112 on the mask 1, the position of the vernier scale pattern 112 in the second placement state and the position of the main scale pattern 111 in the first placement state can be arranged side by side to form a vernier caliper pattern. This makes the vernier scale pattern 1121 in the second exposure pattern and the main scale pattern 1111 in the first exposure pattern side by side, so as to determine the overprinting error by the alignment of the scales of the vernier scale pattern 1121 and the main scale pattern 1111.

[0064] For example, such as Figure 5 As shown, when the overprinting error in a single direction is zero, the vernier scale pattern 1121 and the main scale pattern 1111 extending along that direction are arranged side by side, and their zero scale lines are aligned with each other.

[0065] When the overprinting error in a single direction is not zero, there is a left-right offset between the zero mark of the vernier scale pattern 1121 and the main scale pattern 1111 extending along that direction.

[0066] It is understood that the main scale graphic 111 and the corresponding main scale pattern 1111 both include multiple first scale lines arranged at equal intervals; the vernier scale graphic 112 and the corresponding vernier scale pattern 1121 both include multiple second scale lines arranged at equal intervals; the distance between adjacent first scale lines is greater than the distance between adjacent second scale lines.

[0067] When the overprinting error in a single direction is not zero, a relatively accurate offset can be read from the position of the zero mark of the vernier scale pattern 1121 and the position of the scale line of the vernier scale pattern 1121 and the main scale pattern 1111 that are aligned vertically.

[0068] In addition, it is understood that in actual operation, the first exposure pattern also includes a vernier pattern 1121 corresponding to the vernier pattern 112 in the first placement state, and the second exposure pattern also includes a main scale pattern 1111 corresponding to the main scale pattern 111 in the second placement state; therefore, the vernier pattern 1121 of the first exposure pattern can also be set side by side with the main scale pattern 1111 of the second exposure pattern to form a vernier caliper pattern, so as to read the overprinting error.

[0069] In other words, as long as one of the vernier scale pattern 1121 and the main scale pattern 1111 in the first exposure pattern and the second exposure pattern can be set side by side, it can be used to read the overprinting error.

[0070] Alternatively, in some embodiments, such as Figure 5 As shown, the zero mark of the main scale pattern 111 is located in the middle of the main scale pattern 111, and the zero mark of the vernier scale pattern 112 is located in the middle of the vernier scale pattern 112. This design allows the overprinting error to be read by the deviation of the scale lines when the layer pattern is offset relative to the previous layer pattern in the positive or negative scale direction along the extension direction of the main scale pattern 1111 and the vernier scale pattern 1121.

[0071] In one specific embodiment, such as Figure 3 , Figure 4 and Figure 5 As shown, the main scale graphic 111 has a total length of 1000μm and is divided into 100 equal divisions, with the zero mark located at the bisection point along the length of the main scale graphic 111; the vernier scale graphic 112 has a total length of 980μm and is divided into 100 equal divisions, with the zero mark located at the bisection point along the length of the vernier scale graphic 112.

[0072] When the overprinting error is zero, such as Figure 5 As shown, the zero marks of the corresponding main scale pattern 1111 and vernier scale pattern 1121 are aligned vertically. However, when the overprinting error is not zero, the zero mark of the vernier scale pattern 1121 will shift left or right relative to the zero mark of the main scale pattern 1111. The offset can be read based on the corresponding position of the zero mark of the vernier scale pattern 1121 on the main scale pattern 1111 and the alignment of the corresponding side zero mark.

[0073] For example, when the zero mark of the vernier scale pattern 1121 is offset to the left relative to the zero mark of the main scale pattern 1111, if the zero mark of the vernier scale pattern 1121 is located between the nth and (n+1)th scale marks to the left of the zero mark of the main scale pattern 1111, and the i-th scale mark to the left of the zero mark of the vernier scale pattern 1121 is aligned with the scale mark of the main scale pattern 1111, then the offset can be read as (10n+0.2i) μm. That is, the measurement accuracy of the overlay error in this embodiment is 0.2 μm (200 nm). Similarly, when the zero mark of the vernier scale pattern 1121 is offset to the right relative to the zero mark of the main scale pattern 1111, the reading method is similar and will not be repeated here.

[0074] Understandably, the length and number of scales of the main scale graphic 111 and the vernier scale graphic 112 can be designed according to actual accuracy requirements. For example, the measurement accuracy can be adjusted to 50nm, 100nm, 500nm or other accuracy levels.

[0075] In some embodiments, such as Figure 1 and Figure 2 As shown, the second placement state is rotated by an angle that is an integer multiple of 90° relative to the first placement state.

[0076] like Figure 11 , Figure 12 and Figure 15 As shown, the main scale graphic 111 includes a first main scale 1112 and a second main scale 1113, with the extension direction of the first main scale 1112 being perpendicular to the extension direction of the second main scale 1113.

[0077] The vernier scale graphic 112 includes a first vernier scale 1122 and a second vernier scale 1123, with the extension direction of the first vernier scale 1122 being perpendicular to the extension direction of the second vernier scale 1123.

[0078] The first vernier scale pattern 11221 in the second exposure pattern and the first main scale pattern 11121 in the first exposure pattern constitute a vernier caliper pattern; the second vernier scale pattern 11231 in the second exposure pattern and the second main scale pattern 11131 in the first exposure pattern constitute a vernier caliper pattern.

[0079] In this embodiment, by rotating the second placement state relative to the first placement state by an angle that is an integer multiple of 90°, it is convenient to arrange the main scale pattern 111 and the vernier scale pattern 112 of the mask 1. Taking the rotation angle of the second placement state relative to the first placement state as 90° as an example, the extension direction of the main scale pattern 111 and the extension direction of the vernier scale pattern 112 can be perpendicular to each other, so that the main scale pattern 1111 and the vernier scale pattern 1121 in the first exposure pattern and the second exposure pattern can be arranged side by side.

[0080] Specifically, the rotation angle of the second placement state relative to the first placement state can be 90°, 180°, 270°, etc.

[0081] Meanwhile, by setting a first main scale 1112 and a second main scale 1113 with mutually perpendicular extension directions on the photomask 1, a corresponding first main scale pattern 11121 and a second main scale pattern 11131 are exposed on the wafer; similarly, by setting a first vernier scale 1122 and a second vernier scale 1123 with mutually perpendicular extension directions, a corresponding first vernier scale pattern 11221 and a second vernier scale pattern 11231 are exposed on the wafer.

[0082] In practical applications, by reasonably setting the relative positions of the first main scale 1112 and the first vernier scale 1122, the second main scale 1113 and the second vernier scale 1123, the first vernier scale pattern 11221 in the second exposure pattern and the first main scale pattern 11121 in the first exposure pattern can be arranged side by side to form a vernier caliper pattern. The vernier caliper pattern can be used to detect the overprinting error along the extension direction of the first main scale pattern 11121. Similarly, the second vernier scale pattern 11231 in the second exposure pattern and the second main scale pattern 11131 in the first exposure pattern can be arranged side by side to form a vernier caliper pattern. The vernier caliper pattern can be used to detect the overprinting error along the extension direction of the second main scale pattern 11131.

[0083] In other words, by cooperating with the two sets of main scale pattern 1111 and vernier scale pattern 1121, the two vernier caliper patterns formed can be used to detect overlay errors along two vertical directions. This detection method can better reflect the offset and offset direction of the current layer pattern and the previous layer pattern on the horizontal plane, so as to serve as the basis for lithography machine acceptance or process debugging, or as a daily monitoring indicator for wafer production line.

[0084] Meanwhile, since the first main scale 1112 and the second main scale 1113 are perpendicular to each other, the first vernier scale 1122 and the second vernier scale 1123 are perpendicular to each other, and the second placement state is rotated by an angle that is an integer multiple of 90° relative to the first placement state, this design allows the extension directions of the main scale graphic 111 and the vernier scale graphic 112 to have a certain consistency in the first placement state and the second placement state, making it easier to measure the overprinting error.

[0085] Taking the main scale pattern 111 as an example, in the first placement state, the first main scale 1112 and the second main scale 1113 extend along the X and Y directions of the wafer, respectively. After rotating by an integer multiple of 90°, the first main scale 1112 and the second main scale 1113 still have one extending along the X direction and the other extending along the Y direction.

[0086] Similarly, after rotating by an integer multiple of 90°, the first vernier scale 1122 and the second vernier scale 1123 can maintain the same alignment, with one extending along the X direction and the other along the Y direction. This allows the two sets of main scale patterns 1111 and vernier scale patterns 1121 to cooperate with each other and be used to read the overprinting errors in the X and Y directions, respectively.

[0087] In addition, it is understandable that in actual operation, the first exposure pattern also includes the first vernier scale pattern 11221 and the second vernier scale pattern 11231, and the second exposure pattern also includes the first main scale pattern 11121 and the second main scale pattern 11131; therefore, the vernier scale pattern 1121 of the first exposure pattern can also be arranged side by side with the main scale pattern 1111 of the second exposure pattern to form a vernier caliper pattern so as to read the overprinting error in two directions.

[0088] In some embodiments, such as Figure 1 , Figure 2 and Figure 14 As shown, there are multiple main scale pattern 111, multiple vernier scale pattern 112, and multiple exposure resolution detection pattern 115; the multiple main scale pattern 1111 and multiple vernier scale pattern 1121 in the first exposure pattern and the second exposure pattern can be combined to form multiple overlay accuracy detection patterns; multiple exposure resolution detection patterns 1151 are formed in the first exposure pattern and the second exposure pattern.

[0089] Multiple overlay accuracy detection patterns are centrally symmetrically distributed with respect to the center of the wafer; and / or, multiple exposure resolution detection patterns 1151 are centrally symmetrically distributed with respect to the center of the wafer.

[0090] In this embodiment, by providing multiple main scale patterns 111, multiple vernier scale patterns 112, and multiple exposure resolution detection patterns 115 on the mask 1, the first exposure pattern and the second exposure pattern both include multiple main scale patterns 1111, multiple vernier scale patterns 1121, and multiple exposure resolution detection patterns 1151.

[0091] The multiple main scale patterns 1111 and multiple vernier scale patterns 1121 can be combined to form multiple overlay accuracy detection patterns for detecting overlay errors. These multiple overlay accuracy detection patterns can be located at different positions on the wafer to facilitate the detection of overlay errors at each position. Optionally, by reasonably setting the positions of the main scale pattern 111 and the vernier scale pattern 112, the multiple overlay accuracy detection patterns can be paired in pairs, and each pair of overlay accuracy detection patterns is centrally symmetrical about the center of the wafer, which facilitates the detection of overlay errors at different positions on the wafer. Similarly, multiple exposure resolution detection patterns 1151 are located at different positions on the wafer to facilitate the detection of exposure resolution at each point, thereby serving as the basis for calculating the exposure uniformity of the wafer.

[0092] In some embodiments, such as Figure 1 and Figure 2 As shown, the mask 1 includes four distribution areas 12 and a central area 13. The rotation center of the mask 1 and the geometric center of the central area 13 coincide. The four distribution areas 12 surround the outside of the central area 13 and are centrally symmetrical with respect to the rotation center of the mask 1. The central area 13 is provided with a main scale pattern 111, a vernier scale pattern 112 and an exposure resolution detection pattern 115.

[0093] One of the two adjacent distribution areas 12 is provided with a main scale graphic 111, and the other of the two adjacent distribution areas 12 is provided with a vernier scale graphic 112; at least one of the two adjacent distribution areas 12 is provided with an exposure resolution detection graphic 115.

[0094] In this embodiment, by dividing the mask 1 into a central region 13 located at and near the rotation center and four distribution regions 12 surrounding the central region 13, for two adjacent distribution regions 12, before and after the mask 1 rotates 90°, the two distribution regions 12 can be exposed on different photolithographic layers in the same area of ​​the wafer to form two exposure patterns. The two exposure patterns are superimposed to detect overlay errors. For a single distribution region 12, before and after the mask 1 rotates 90°, the same distribution region 12 can be exposed on two adjacent areas of the wafer to form exposure patterns, so as to detect exposure resolution and uniformity.

[0095] Specifically, a main scale pattern 111 and a vernier scale pattern 112 are respectively provided in two adjacent distribution areas 12. That is to say, before and after the mask 1 is rotated, the main scale pattern 1111 and the vernier scale pattern 1121 formed by the two distribution areas 12 in the same area of ​​the wafer can be combined with each other to facilitate the detection of overlay error in the area.

[0096] Meanwhile, at least one of the two adjacent distribution areas 12 is provided with an exposure resolution detection pattern 115. Before and after the mask 1 is rotated 90°, the exposure resolution detection pattern 115 of a single distribution area 12 can form an exposure resolution detection pattern 1151 on two adjacent areas of the wafer respectively, so as to detect the exposure resolution at the corresponding position.

[0097] In addition, the central area 13 is also provided with a main scale pattern 111, a vernier scale pattern 112, and an exposure resolution detection pattern 115. Before and after the mask 1 is rotated 90°, the central area 13 exposes and forms a matching main scale pattern 1111 and vernier scale pattern 1121 on the area of ​​the wafer near the center, which is used to detect the overlay error in the center area of ​​the wafer. The exposure resolution detection pattern 1151 formed by the exposure of the central area 13 in the center area detects the exposure resolution of the center area, as well as the exposure resolution of the surrounding area, to detect the exposure uniformity of the entire wafer.

[0098] In some embodiments, such as Figure 1 , Figure 6 , Figure 7 , Figure 8 and Figure 9 As shown, the mask pattern 11 also includes a first target pattern 113 and a second target pattern 114. The first target pattern 113 and the second target pattern 114 are related by a preset offset relative to the rotation center of the mask 1. The first target pattern 1131 formed by the first target pattern 113 in the second placement state is aligned with the second target pattern 1141 formed by the second target pattern 114 in the first placement state.

[0099] In this embodiment, by setting a first target pattern 113 and a second target pattern 114 on the mask 1 respectively, the first target pattern 113 and the second target pattern 114 on the mask 1 can be set at intervals along the rotation direction of the mask 1, so that the mask 1 can form different exposure patterns (i.e., the first target pattern 1131 and the second target pattern 1141) in the front and back photolithography layers on the wafer by switching between the first placement state and the second placement state. The alignment degree of the two exposure patterns is used to confirm whether the mask 1 in the second placement state is aligned with the wafer.

[0100] In addition, it is understood that in actual operation, the first exposure pattern also includes the second target pattern 1141, and the second exposure pattern also includes the first target pattern 1131; therefore, the second target pattern 1141 of the first exposure pattern can also be aligned with the first target pattern 1131 of the second exposure pattern in order to confirm whether the mask 1 in the second placement state is aligned with the wafer.

[0101] Specifically, in some embodiments, such as Figure 6 , Figure 7 and Figure 8As shown, the first target pattern 113 can be a cross shape, and the second target pattern 114 is a ring shape that matches the cross shape. The ring shape has notches at the four quarter points. When the first target pattern 1131 corresponding to the first target pattern 113 and the second target pattern 1141 corresponding to the second target pattern 114 are aligned, the center of the cross shape coincides with the center of the ring shape, and the four sides of the cross shape are inserted into the four notches of the ring shape.

[0102] Optionally, such as Figure 9 As shown, the second target pattern 114 can also be a square pattern with a cross-shaped space in the middle. When the first target pattern 1131 corresponding to the first target pattern 113 and the second target pattern 1141 corresponding to the second target pattern 114 are aligned, the cross-shaped pattern is located in the cross-shaped space of the square pattern.

[0103] In some embodiments, such as Figure 1 As shown, there are multiple first target patterns 113 and multiple second target patterns 114. The multiple first target patterns 113 and multiple second target patterns 114 are arranged alternately along the rotation direction of the mask 1. The angles formed by the lines connecting the geometric centers of adjacent first target patterns 113 and second target patterns 114 to the rotation center of the mask 1 are equal to the preset angles.

[0104] In this embodiment, by arranging multiple first target patterns 113 and second target patterns 114 alternately along the rotation direction on the mask 1, before and after the mask 1 rotates, the first target pattern 1131 formed by the first target pattern 113 can be aligned with the second target pattern 1141 formed by the second target pattern 114 on the adjacent sides along the rotation direction, thereby forming multiple patterns along the rotation direction of the mask 1 that can be used to confirm whether the mask 1 in the second placement state is aligned with the wafer.

[0105] Specifically, such as Figure 10 and Figure 15 As shown, in some embodiments, the exposure resolution detection pattern 115 includes at least one of a first detection block 1152, a second detection block 1153, and a third detection block 1154; wherein, the first detection block 1152 includes a plurality of line patterns arranged parallel to each other along a first direction and extending along a second direction; the second detection block 1153 includes a plurality of line patterns arranged parallel to each other along the second direction and extending along the first direction; the first direction and the second direction are perpendicular; the third detection block 1154 includes a plurality of square patterns arranged in an array.

[0106] In this embodiment, the line patterns of the first detection block 1152 and the second detection block 1153 are arranged orthogonally, and the exposure patterns formed on the wafer can be used to test the exposure resolution in two directions respectively. The two-dimensional pattern (square pattern) of the third detection block 1154 can be used to verify the imaging fidelity of the wafer corners and edges.

[0107] Optionally, the third detection block 1154 can also be replaced by any one or more of the following: rectangular array, comb pattern, aperture array pattern, and step pattern.

[0108] In one specific embodiment, such as Figure 10 As shown, the exposure resolution detection pattern 115 includes three first detection blocks 1152, three second detection blocks 1153, and three third detection blocks 1154. The above nine detection blocks are arranged in a 3x3 square array. The three detection blocks in the first row from top to bottom are all first detection blocks 1152. From left to right, the line width and line spacing of the first first detection block 1152 are both 1μm, the line width and line spacing of the second first detection block 1152 are both 2μm, and the line width and line spacing of the third first detection block 1152 are both 3μm.

[0109] The three detection blocks in the second row from top to bottom are all second detection blocks 1153. From left to right, the line width and line spacing of the first second detection block 1153 are both 1μm, the line width and line spacing of the second second detection block 1153 are both 2μm, and the line width and line spacing of the third second detection block 1153 are both 3μm.

[0110] The three detection blocks in the third row from top to bottom are all third detection blocks 1154. From left to right, the side length and spacing of the square shapes in the first third detection block 1154 are 1μm, the side length and spacing of the square shapes in the second third detection block 1154 are 2μm, and the side length and spacing of the square shapes in the third third detection block 1154 are 3μm.

[0111] In one specific embodiment, such as Figure 1 and Figure 2 As shown, the four distribution areas 12 are quadrants A, B, C and D arranged in a clockwise direction.

[0112] Quadrant A and Quadrant C are centrally symmetrically distributed with respect to the rotation center of mask 1. Quadrant A and Quadrant C each include six first combined patterns 121. The six first combined patterns 121 are divided into two groups, each group including three first combined patterns 121. The three first combined patterns 121 in each group are arranged at equal intervals along the circumference of mask 1, and the two groups of first combined patterns 121 are arranged at radial intervals along mask 1.

[0113] like Figure 11 As shown, the first combined pattern 121 includes an exposure resolution detection pattern 115, a first main scale 1112 and a second main scale 1113 extending perpendicularly to each other, and a first target pattern 113.

[0114] Quadrant B and Quadrant D are centrally symmetrical about the rotation center of mask 1. Both quadrant B and quadrant D include six second combination patterns 122. The six second combination patterns 122 are divided into two groups, each group including three second combination patterns 122. The three second combination patterns 122 in each group are equally spaced along the circumference (i.e., rotation direction) of mask 1, and the two groups of second combination patterns 122 are arranged at radial intervals along mask 1.

[0115] like Figure 12 As shown, the second combined graphic 122 includes two sets of mutually perpendicularly extending first vernier scales 1122 and second vernier scales 1123, as well as a second target graphic 114.

[0116] Before and after the mask 1 is rotated 90°, the first combined pattern 121 on quadrant A and quadrant C is exposed on the wafer to form the first combined pattern, and the second combined pattern 122 on quadrant B and quadrant D is exposed on the wafer to form the second combined pattern. The first combined pattern and the second combined pattern can be combined to form a complete detection pattern group 2.

[0117] like Figure 15 As shown, the detection pattern group 2 includes at least an exposure resolution detection pattern 1151, a first main scale pattern 11121 and a first vernier scale pattern 11221 arranged side by side, a second main scale pattern 11131 and a second vernier scale pattern 11231 arranged side by side, and a first target pattern 1131 and a second target pattern 1141 aligned with each other.

[0118] like Figure 13 As shown, the central area 13 is provided with a third combined pattern 131, a fourth combined pattern 132 and a fifth combined pattern 133 arranged sequentially along the circumference of the mask 1; The third combined graphic 131 and the fifth combined graphic 133 each include a first vernier scale 1122 and a second vernier scale 1123 that extend perpendicularly to each other, as well as a second target graphic 114; the fourth combined graphic 132 is the same as the second combined graphic 122.

[0119] Before and after the mask 1 is rotated 90°, the third combined pattern 131, the fourth combined pattern 132, and the fifth combined pattern 133 of the central region 13 are exposed on the wafer to form the third combined pattern, the fourth combined pattern, and the fifth combined pattern, respectively. The fourth combined pattern, together with the third combined pattern and the fifth combined pattern, forms two complete detection pattern groups 2 (e.g., ...). Figure 16(As shown).

[0120] In summary, before and after the mask 1 rotates 90°, quadrants A, B, C, and D, along with the central region 13, can be exposed on the wafer to form twenty-six detection pattern groups 2. Twelve detection pattern groups 2 are evenly arranged along the outer edge of the wafer, and twelve are evenly arranged along the inner edge. Two detection pattern groups 2 are located near the center of the wafer to facilitate the detection of overlay errors and exposure resolution at various positions on the wafer based on each detection pattern group 2, and to calculate the wafer's exposure uniformity based on the detection results at each position. During actual inspection, since the two detection pattern groups 2 in the central region are relatively close, one can be selected for inspection, meaning inspection is performed based on the twenty-five detection pattern groups 2 on the wafer.

[0121] It is understandable that the distribution of the mask pattern 11 is adjusted according to actual needs (such as the size and specifications of the wafer) so that the arrangement of the exposure patterns on the wafer can meet the inspection requirements. For example, for larger wafers, thirty-seven or forty-nine inspection pattern groups 2 can be formed on the wafer for inspection.

[0122] Optionally, in some embodiments, a first target pattern 113 may be provided at the left and right ends of the mask 1, and a second target pattern 114 may be provided at the top and bottom ends of the mask 1.

[0123] On the other hand, the present invention also provides a detection method based on the mask 1 provided in any of the above embodiments. It is understood that by using the mask 1 of the above embodiments, the detection method of the present invention also has the advantages of the mask 1, which will not be repeated here.

[0124] like Figure 17 As shown, the detection method of the present invention includes the following steps: Step S101: Place the photomask in the photolithography machine in the first placement state, and form the first exposure pattern on the first photolithography layer of the wafer by exposure.

[0125] Step S102: Rotate the mask to the second placement state and form a second exposure pattern by exposing the second photolithography layer on the wafer.

[0126] Step S103: Determine the overlay accuracy and exposure resolution based on the first exposure pattern and the second exposure pattern.

[0127] Before inspection, the mask 1 can be placed in the optical path of the lithography machine in a first placement state so that the first lithography layer of the wafer can be exposed based on the mask 1, thereby forming a first exposure pattern in the first lithography layer. The first exposure pattern includes at least the first set of etched patterns formed based on the first set of etched patterns and the exposure resolution detection pattern 1151 formed based on the exposure resolution detection pattern 115.

[0128] After the first photolithography layer is exposed, the wafer can be kept stationary while the mask 1 is rotated to the second placement state. The position of the mask pattern 11 on the mask 1 in the second placement state changes so as to form a second exposure pattern in the second photolithography layer of the wafer. The second exposure pattern includes at least a second set of etched patterns formed based on the exposure of the second set of etched patterns and an exposure resolution detection pattern 1151 formed based on the exposure resolution detection pattern 115.

[0129] The first exposure pattern and the second exposure pattern are superimposed on each other, and the first set of engraving patterns and the second set of engraving patterns are combined to form an overprinting accuracy detection pattern suitable for detecting overprinting accuracy, so as to determine the overprinting error through the overprinting accuracy detection pattern. At the same time, the exposure resolution detection pattern 1151 in the first exposure pattern and the second exposure pattern can be used to detect the exposure resolution.

[0130] In addition, it is understood that in actual operation, the first exposure pattern also includes the second set of engraving patterns corresponding to the second set of engraving patterns in the first placement state, and the second exposure pattern also includes the first set of engraving patterns corresponding to the first set of engraving patterns in the second placement state; therefore, the second set of engraving patterns of the first exposure pattern can also be paired and combined with the first set of engraving patterns of the second exposure pattern to form an overlay accuracy detection pattern suitable for detecting overlay accuracy.

[0131] Optionally, in some embodiments, there are multiple sets of first engraving patterns, multiple sets of second engraving patterns, and multiple exposure resolution detection patterns 115; the second set of engraving patterns in the second exposure pattern and the first set of engraving patterns in the first exposure pattern can be combined to form multiple engraving accuracy detection patterns with different positions; multiple exposure resolution detection patterns 1151 with different positions are formed in the first exposure pattern and the second exposure pattern.

[0132] Accordingly, the detection method also includes the following steps: The exposure uniformity of the wafer is determined based on multiple overlay accuracy detection patterns and multiple exposure resolution detection patterns.

[0133] In this embodiment, by providing multiple first sets of engraved patterns, multiple second sets of engraved patterns, and multiple exposure resolution detection patterns 115 on the mask 1, the first exposure pattern and the second exposure pattern both include multiple first sets of engraved patterns, multiple second sets of engraved patterns, and multiple exposure resolution detection patterns 1151.

[0134] Among them, multiple first sets of engraving patterns and multiple second sets of engraving patterns can be combined to form multiple engraving accuracy detection patterns for detecting engraving errors. Multiple engraving accuracy detection patterns can be located at different positions on the wafer to facilitate the detection of engraving errors at each position. Similarly, multiple exposure resolution detection patterns 1151 are located at different positions on the wafer to facilitate the detection of exposure resolution at each point and serve as the basis for calculating the exposure uniformity of the wafer.

[0135] In other words, based on the above-mentioned detection method of mask 1, multiple indicators such as overlay accuracy, exposure resolution and exposure uniformity can be detected by rotating a single mask 1, which greatly simplifies the detection process.

[0136] In some embodiments, the mask pattern 11 further includes a plurality of first target patterns 113 and a plurality of second target patterns 114. When performing inspection, the inspector can determine whether the mask 1 has been rotated into place by checking whether the first target pattern 1131 formed by the first target pattern 113 and the second target pattern 1141 formed by the corresponding second target pattern 1141 are aligned before and after the mask 1 is rotated. After confirming that the corresponding first target pattern 1131 and second target pattern 1141 are aligned with each other, the overlay accuracy and exposure resolution are determined based on the first exposure pattern and the second exposure pattern.

[0137] Finally, it should be noted that the above embodiments are only for illustrating the present invention and not for limiting the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications, or equivalent substitutions of the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention and should be covered within the scope of the claims of the present invention.

Claims

1. A photomask, characterized in that, The mask pattern (11) on the mask plate (1) includes an exposure resolution detection pattern (115) and an overlay accuracy detection pattern. The exposure resolution detection pattern (115) and the overlay accuracy detection pattern are spatially separated on the mask plate (1). The overlay accuracy detection pattern includes a first overlay pattern and a second overlay pattern. The mask (1) can be rotated by a preset angle from a first position state to a second placement state; in the first placement state, a first exposure pattern is formed on the wafer based on the mask pattern; in the second placement state, a second exposure pattern is formed on the wafer based on the mask pattern; both the first exposure pattern and the second exposure pattern include a first set of etched patterns corresponding to the first set of etched patterns, a second set of etched patterns corresponding to the second set of etched patterns, and an exposure resolution detection pattern (1151) corresponding to the exposure resolution detection pattern (115). Wherein, the first set of engraving patterns in the first exposure pattern is paired with the second set of engraving patterns in the second exposure pattern, and / or, the second set of engraving patterns in the first exposure pattern is paired with the first set of engraving patterns in the second exposure pattern to form an overlay accuracy detection pattern suitable for detecting overlay accuracy; the exposure resolution detection pattern (1151) in the first exposure pattern and / or the second exposure pattern is suitable for detecting the exposure resolution of the wafer; the overlay accuracy detection pattern and the exposure resolution detection pattern (1151) do not interfere with each other.

2. The photomask according to claim 1, characterized in that, In the first set of engraved patterns and the second set of engraved patterns, one is the main scale pattern (111) and the other is the vernier scale pattern (112); in the first exposure pattern and the second exposure pattern, the main scale pattern (1111) corresponding to the main scale pattern (1111) and the vernier scale pattern (1121) corresponding to the vernier scale pattern (112) together constitute the vernier caliper pattern.

3. The photomask according to claim 2, characterized in that, The preset angle is an integer multiple of 90°; The main scale graphic (111) includes a first main scale (1112) and a second main scale (1113), wherein the extension direction of the first main scale (1112) and the extension direction of the second main scale (1113) are perpendicular to each other. The vernier scale graphic (112) includes: a first vernier scale (1122) and a second vernier scale (1123), wherein the extension direction of the first vernier scale (1122) is perpendicular to the extension direction of the second vernier scale (1123); The first vernier scale pattern (11221) in the second exposure pattern and the first main scale pattern (11121) in the first exposure pattern constitute the vernier caliper pattern; the second vernier scale pattern (11231) in the second exposure pattern and the second main scale pattern (11131) in the first exposure pattern constitute the vernier caliper pattern.

4. The photomask according to claim 1, characterized in that, There are multiple sets of the first set of engraving patterns, the second set of engraving patterns, and the exposure resolution detection pattern (115); The second set of engraving patterns in the second exposure pattern and the first set of engraving patterns in the first exposure pattern can be combined to form multiple engraving accuracy detection patterns; multiple exposure resolution detection patterns (1151) are formed in the first exposure pattern and the second exposure pattern. The plurality of overlay accuracy detection patterns are centrally symmetrically distributed with respect to the center of the wafer; and / or, the plurality of exposure resolution detection patterns (1151) are centrally symmetrically distributed with respect to the center of the wafer.

5. The photomask according to claim 4, characterized in that, The mask includes four distribution areas (12) and a central area (13), the rotation center of the mask and the geometric center of the central area (13) coincide; the four distribution areas (12) surround the outside of the central area (13), and the four distribution areas (12) are centrally symmetrically distributed with respect to the rotation center of the mask; The central area (13) is provided with the first set of engraved patterns, the second set of engraved patterns and the exposure resolution detection pattern (115). One of the two adjacent distribution areas (12) is provided with the first set of engraved patterns, and the other of the two adjacent distribution areas (12) is provided with the second set of engraved patterns; at least one of the two adjacent distribution areas (12) is provided with the exposure resolution detection pattern (115).

6. The photomask according to claim 1, characterized in that, The mask pattern (11) also includes: The first target pattern (113) and the second target pattern (114) are provided with a preset offset relationship relative to the rotation center of the mask. The first target pattern (1131) formed by the first target pattern (113) in the second placement state is aligned with the second target pattern (1141) formed by the second target pattern (114) in the first placement state.

7. The photomask according to claim 6, characterized in that, There are multiple first target patterns (113) and multiple second target patterns (114). The multiple first target patterns (113) and multiple second target patterns (114) are arranged alternately along the rotation direction of the mask. The angle formed by the lines connecting the geometric centers of adjacent first target patterns (113) and second target patterns (114) to the rotation center of the mask is equal to the preset angle.

8. The photomask according to claim 1, characterized in that, The exposure resolution detection pattern includes at least one of the following patterns: The first detection block (1152) includes multiple line graphics arranged in parallel along the first direction and extending along the second direction; The second detection block (1153) includes multiple line graphics arranged parallel to the second direction and extending along the first direction; the first direction and the second direction are perpendicular. The third detection block (1154) includes multiple square patterns arranged in an array.

9. A detection method based on the mask according to any one of claims 1 to 8, characterized in that, include: The photomask is placed in the photolithography machine in the first placement state, and the first exposure pattern is formed by exposing the first photolithography layer on the wafer. The photomask is rotated to the second placement state, and the second exposure pattern is formed by exposing the second photolithography layer of the wafer. Based on the first exposure pattern and the second exposure pattern, the overlay accuracy and exposure resolution are determined.

10. The detection method according to claim 9, characterized in that, There are multiple sets of the first set of engraving patterns, the second set of engraving patterns, and the exposure resolution detection pattern (115); the second set of engraving patterns in the second exposure pattern and the first set of engraving patterns in the first exposure pattern can be combined to form multiple engraving accuracy detection patterns with different positions; multiple exposure resolution detection patterns (1151) with different positions are formed in the first exposure pattern and the second exposure pattern. The exposure uniformity of the wafer is determined based on multiple overlay accuracy detection patterns and multiple exposure analysis detection patterns.

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