Mask patterning and metrology method
By designing the mask pattern as a square outer and inner layer pattern, with the outer layer pattern having outward-extending straight line segments, the problem of defects introduced by mask markings was solved. This enabled simultaneous measurement of key dimensions and overlay errors, reducing defect risks and costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHONGQING XINLIAN MICROELECTRONICS CO LTD
- Filing Date
- 2026-05-14
- Publication Date
- 2026-07-10
Smart Images
Figure CN122362736A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of integrated circuit technology, and in particular to a photomask pattern and measurement method. Background Technology
[0002] Figure 1 This is a schematic diagram of a photomask pattern in the prior art. Figure 2 This is a schematic diagram of overlay marking patterns in existing technology. Figure 3 This is a schematic diagram of key dimension marking graphics in existing technology. For example... Figures 1 to 3 As shown, in the chip manufacturing process, the overlay accuracy (OVL) and critical dimension (CD) of the photolithography layer require separate OVL mark and CDB mark designs for measurement. Specifically, the overlay mark 11 in mask pattern 10 is used to measure overlay accuracy; the critical dimension mark 12 in mask pattern 10 is used to measure critical dimensions. For non-key layers, a single shot (exposure field) typically requires four overlay mark patterns 11 for 10 Pa (ten-parameter model) OVL compensation, and one critical dimension mark 12 is needed for critical dimension measurement. The ten-parameter model (10 Pa terms) can decompose and compensate for errors at both the wafer-level and exposure field-level dimensions. The wafer-level dimension includes overall offset, rotation, orthogonality, etc.; the exposure field-level dimension includes scaling and rotation of individual exposure fields, etc.
[0003] Because the number of markings on the photomask is large, it is easy to introduce defects in subsequent processes, such as residues and particles. In the subsequent improvement process, not only will it take time, effort and cost to improve, but it will also cause some product yield loss. Summary of the Invention
[0004] The purpose of this invention is to provide a mask pattern and measurement method to solve the problem that a large number of mask markings can easily introduce defects in subsequent processes, resulting in a loss of yield for some products.
[0005] To solve the above-mentioned technical problems, the present invention provides a photomask pattern, comprising:
[0006] Multiple front-layer graphics, including an outer front-layer graphic and an inner front-layer graphic surrounded by the outer front-layer graphic, wherein the inner front-layer graphic is square in shape, and the outer front-layer graphic includes a central square region and a first straight line segment extending outward from the four sides of the square region.
[0007] Multiple layer graphics, the multiple layer graphics including an outer layer graphic and an inner layer graphic surrounded by the outer layer graphic, the inner layer graphic being square in shape, and the outer layer graphic including a central square region and a second straight line segment extending outward from the four sides of the square region;
[0008] The current layer pattern is used to obtain key dimensions, and the current layer pattern and the previous layer pattern are used to obtain overlay error.
[0009] Optionally, the key dimensions include the key dimensions of dense line areas and the key dimensions of isolated line areas.
[0010] Optionally, the second straight line segment of the layered graphic is used to obtain the key dimensions of isolated line regions.
[0011] Optionally, multiple in-layer graphics may include at least three in-layer graphics.
[0012] Optionally, the middle layer of the graphic is used to obtain the key dimensions of isolated line areas.
[0013] Optionally, the overprinting error includes overprinting error in a first direction and overprinting error in a second direction, wherein the first direction and the second direction are located in the plane of the mask and are perpendicular to each other.
[0014] Based on the same inventive concept, the present invention also provides a measurement method, comprising:
[0015] A substrate is provided on which a plurality of front layer patterns and a plurality of current layer patterns are sequentially formed. The plurality of front layer patterns include an outer front layer pattern and an inner front layer pattern surrounded by the outer front layer pattern. The inner front layer pattern is square in shape. The outer front layer pattern includes a central square region and a first straight line segment extending outward from the four sides of the square region. The plurality of current layer patterns include an outer current layer pattern and an inner current layer pattern surrounded by the outer current layer pattern. The inner current layer pattern is square in shape. The outer current layer pattern includes a central square region and a second straight line segment extending outward from the four sides of the square region.
[0016] Measure the key dimensions of the current layer pattern, and simultaneously measure the overprinting error between the current layer pattern and the previous layer pattern.
[0017] Optionally, measuring the key dimensions of the current layer graphic includes measuring the key dimensions of dense line regions and measuring the key dimensions of isolated line regions.
[0018] Optionally, the overprinting error includes overprinting error in a first direction and overprinting error in a second direction, wherein the first direction and the second direction are located in the plane of the mask and are perpendicular to each other.
[0019] Optionally, a first measuring device is used to measure the key dimensions of the current graphic, and a second measuring device is used to measure the overprinting error between the current graphic and the previous graphic.
[0020] In a mask pattern provided by this invention, multiple front-layer patterns and multiple current-layer patterns are set. The multiple front-layer patterns include an outer front-layer pattern and an inner front-layer pattern surrounded by the outer front-layer pattern. The inner front-layer pattern is square in shape, and the outer front-layer pattern includes a central square area and a first straight line segment extending outward from the four sides of the square area. The multiple current-layer patterns include an outer current-layer pattern and an inner current-layer pattern surrounded by the outer current-layer pattern. The inner current-layer pattern is square in shape, and the outer current-layer pattern includes a central square area and a second straight line segment extending outward from the four sides of the square area. The current-layer pattern is used to obtain critical dimensions, and the current-layer pattern and the front-layer pattern are used to obtain overlay errors. The mask pattern provided by this invention can simultaneously measure critical dimensions and overlay errors, reducing the number of marking patterns on the mask and thus reducing defect sources. Furthermore, the mask pattern design provided by this invention is relatively simple and cost-effective. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of a photomask pattern in the prior art.
[0022] Figure 2 This is a schematic diagram of overlay marking patterns in existing technology.
[0023] Figure 3 This is a schematic diagram of the key dimension marking graphics in the prior art.
[0024] Figure 4 This is a schematic diagram of the mask pattern according to an embodiment of the present invention.
[0025] Figure 5 This is a partial enlarged view of the mask pattern according to an embodiment of the present invention.
[0026] Figure 6 This is a flowchart of the measurement method according to an embodiment of the present invention.
[0027] Figures 1 to 3 In the middle: 10-mask pattern; 11-overlay mark pattern; 12-key dimension mark pattern.
[0028] Figures 4 to 5In the diagram: 20 - Mask pattern; 21 - Marker pattern; 211 - Front layer pattern; 2111 - Outer front layer pattern; 2111a - Square region; 2111b - First straight line segment; 2112 - Inner front layer pattern; 212 - Current layer pattern; 2121 - Outer current layer pattern; 2121a - Square region; 2121b - First straight line segment; 2122 - First inner current layer pattern; 2123 - Second inner current layer pattern. Detailed Implementation
[0029] Hereinafter, embodiments of the present application will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the present application. Repeated reference numerals may be used in the various embodiments; these repeated reference numerals are for simplicity and clarity only and do not indicate a relationship between the various embodiments.
[0030] Furthermore, in this application, spatial relationship terms such as "below," "under," "above," and "over" can be used to describe the relationship between one element and another in the accompanying drawings. In addition to the orientations shown in the drawings, these spatial relationship terms may also include different orientations of the device / structure during use (e.g., rotation of 90 degrees). The interpretation of the aforementioned spatial relationship terms should be adjusted accordingly for these different orientations.
[0031] In the description of this application, the term "connection" or similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. For example, in this application, the formation of a first feature over a second feature can include direct or indirect contact between the first and second features.
[0032] In the embodiments described in this application, the term "about" or a term with an equivalent meaning can refer to a given number of values that vary within, for example, 10% of the value. It is understood that for numerical values not defined by terms such as "about" in this application, the numerical value may also have a certain range of fluctuation, provided that the desired technical effect of the embodiments of this application can be achieved, and the numerical values described in the embodiments are merely exemplary.
[0033] Figure 4 This is a schematic diagram of the mask pattern according to an embodiment of the present invention. Figure 5 This is a partially enlarged view of the mask pattern according to an embodiment of the present invention. For example... Figure 4 and Figure 5 As shown, this embodiment provides a mask pattern 20, and a marking pattern 21 is formed in the cutting area of the mask pattern 20. The marking pattern 21 includes:
[0034] Multiple front-layer graphics 211, the multiple front-layer graphics 211 including an outer front-layer graphics 2111 and an inner front-layer graphics 2112 surrounded by the outer front-layer graphics 2111, the inner front-layer graphics 2112 being square in shape, the outer front-layer graphics 2111 including a central square region 2111a and a first straight line segment 2111b extending outward from the four sides of the square region 2111a;
[0035] Multiple layer graphics 212, the multiple layer graphics 212 include an outer layer graphic 2121 and an inner layer graphic surrounded by the outer layer graphic 2121, the inner layer graphic is square in shape, the outer layer graphic 2121 includes a central square region 2121a and a second straight line segment 2121b extending outward from the four sides of the square region 2121a;
[0036] The current layer pattern 212 is used to obtain the key dimensions of the photolithography pattern, and the current layer pattern 212 and the previous layer pattern 211 are used to obtain the overlay error.
[0037] Please continue to refer to this. Figure 1 The key dimensions include a key dimension d2 for dense line regions and a key dimension d1 for isolated line regions. The second straight line segment 2121b of the layer graphic is used to obtain the key dimension d1 of the isolated line regions. Multiple layer graphics 212 include at least three layer graphics. The middle layer graphic is used to obtain the key dimension d2 of the dense line regions. In this embodiment, the number of layer graphics 212 is, for example, three, including an outer layer graphic 2121, a first inner layer graphic 2122, and a second inner layer graphic 2123. The first inner layer graphic 2122 is located between the outer layer graphic 2121 and the second inner layer graphic 2123; therefore, the first inner layer graphic 2122 is used to obtain the key dimension d2 of the dense line regions.
[0038] Please continue to refer to this. Figure 1 The current layer pattern 212 and the previous layer pattern 211 are used to obtain the overlay error. The overlay error includes an overlay error dx in a first direction and an overlay error dy in a second direction, wherein the first direction and the second direction are located in the mask plane and are perpendicular to each other. The first direction is, for example, the X direction, and the second direction is, for example, the Y direction. The overlay error dx in the first direction and the overlay error dy in the second direction can be obtained by measuring the shift distance of the center position of the border of the current layer pattern 212 and the previous layer pattern 211.
[0039] In this embodiment, the number of marker patterns 21 in the dicing area of the mask pattern 20 is four. These four marker patterns 21 can be compensated for with 10 Pa (ten-parameter model) OVL (overlay error). The ten-parameter model (10 Pa terms) can decompose and compensate for errors at both the wafer-level and exposure field-level dimensions. The wafer-level dimension includes overall offset, rotation, orthogonality, etc.; the exposure field-level dimension includes scaling, rotation, etc. of individual exposure fields.
[0040] The mask pattern in this embodiment can simultaneously measure critical dimensions and overlay errors. The mask pattern in this embodiment can be applied to non-critical lithography layers, lithography layers with critical dimensions greater than or equal to 0.5µm, such as ion implantation process layers, lightly doped drain layers (LDD), or back-end pad layers.
[0041] Figure 6 This is a flowchart of the measurement method according to an embodiment of the present invention. Figure 6 As shown, this embodiment also provides a measurement method, including:
[0042] Step S10: Provide a substrate on which a plurality of front layer patterns and a plurality of current layer patterns are sequentially formed. The plurality of front layer patterns include an outer front layer pattern and an inner front layer pattern surrounded by the outer front layer pattern. The inner front layer pattern is square in shape. The outer front layer pattern includes a central square region and a first straight line segment extending outward from the four sides of the square region. The plurality of current layer patterns include an outer current layer pattern and an inner current layer pattern surrounded by the outer current layer pattern. The inner current layer pattern is square in shape. The outer current layer pattern includes a central square region and a second straight line segment extending outward from the four sides of the square region.
[0043] Step S20: Measure the key dimensions of the current layer graphic, and simultaneously measure the overprinting error between the current layer graphic and the previous layer graphic.
[0044] In step S20, measuring the key dimensions of the current layer pattern 212 includes measuring the key dimensions of the dense line region and the key dimensions of the isolated line region. The second straight line segment 2121b of the current layer pattern corresponds to the isolated line region (ISO position), and the key dimension d1 of the isolated line region is obtained by measuring the second straight line segment 2121b of the current layer pattern. Multiple current layer patterns 212 include at least three current layer patterns. The current layer pattern located in the middle corresponds to the dense line region, and the key dimension d2 of the dense line region is obtained by measuring the current layer pattern located in the middle. In this embodiment, the number of current layer patterns 212 is, for example, three, including an outer current layer pattern 2121, a first inner current layer pattern 2122, and a second inner current layer pattern 2123. The first inner current layer pattern 2122 is located between the outer current layer pattern 2121 and the second inner current layer pattern 2123; therefore, the key dimension of the first inner current layer pattern 2122 is measured to obtain the key dimension d2 of the dense line region. The key dimensions of the current graphic 212 are measured using a first measuring device, such as an imaging optical measuring device, for example, an Archer 800.
[0045] In step S20, the overlay error between the current layer pattern 212 and the previous layer pattern 211 is measured. The overlay error includes an overlay error dx in a first direction and an overlay error dy in a second direction, the first and second directions being located in the mask plane and perpendicular to each other. The first direction is, for example, the X direction, and the second direction is, for example, the Y direction. The overlay error dx in the first direction and the overlay error dy in the second direction can be obtained by measuring the shift distance between the center positions of the borders of the current layer pattern 212 and the previous layer pattern 211. A second measuring device is used to measure the overlay error between the current pattern and the previous layer pattern. The second measuring device is, for example, a CDSEM (Critical Dimension Scanning Electron Microscope).
[0046] In summary, the mask pattern provided in this embodiment of the invention comprises multiple front-layer patterns and multiple current-layer patterns. The multiple front-layer patterns include an outer front-layer pattern and an inner front-layer pattern surrounded by the outer front-layer pattern. The inner front-layer pattern is square in shape, and the outer front-layer pattern includes a central square region and a first straight line segment extending outward from the four sides of the square region. Similarly, the multiple current-layer patterns include an outer current-layer pattern and an inner current-layer pattern surrounded by the outer current-layer pattern. The inner current-layer pattern is square in shape, and the outer current-layer pattern includes a central square region and a second straight line segment extending outward from the four sides of the square region. The current-layer pattern is used to obtain critical dimensions, and the current-layer pattern and the front-layer patterns are used to obtain overlay errors. The mask pattern provided by this invention can simultaneously measure critical dimensions and overlay errors, reducing the number of marking patterns on the mask and thus reducing defect sources. Furthermore, the mask pattern design provided by this invention is relatively simple and cost-effective.
[0047] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to mutually. In addition, different parts between embodiments can also be combined with each other, and this invention does not limit this.
[0048] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.
Claims
1. A photomask pattern, characterized in that, include: Multiple front-layer graphics, including an outer front-layer graphic and an inner front-layer graphic surrounded by the outer front-layer graphic, wherein the inner front-layer graphic is square in shape, and the outer front-layer graphic includes a central square region and a first straight line segment extending outward from the four sides of the square region. Multiple layer graphics, the multiple layer graphics including an outer layer graphic and an inner layer graphic surrounded by the outer layer graphic, the inner layer graphic being square in shape, and the outer layer graphic including a central square region and a second straight line segment extending outward from the four sides of the square region; The current layer pattern is used to obtain key dimensions, and the current layer pattern and the previous layer pattern are used to obtain overlay error.
2. The mask pattern as described in claim 1, characterized in that, The key dimensions include the key dimensions of densely packed line areas and the key dimensions of isolated line areas.
3. The mask pattern as described in claim 2, characterized in that, The second straight line segment of the current layer graphic is used to obtain the key dimensions of isolated line areas.
4. The mask pattern as described in claim 2, characterized in that, Multiple in-layer graphics include at least three in-layer graphics.
5. The mask pattern as described in claim 4, characterized in that, The layer graphic located in the middle is used to obtain the key dimensions of isolated line areas.
6. The mask pattern as described in claim 1, characterized in that, The overprinting error includes overprinting error in a first direction and overprinting error in a second direction, wherein the first direction and the second direction are located in the plane of the mask and are perpendicular to each other.
7. A measurement method, characterized in that, include: A substrate is provided on which a plurality of front layer patterns and a plurality of current layer patterns are sequentially formed. The plurality of front layer patterns include an outer front layer pattern and an inner front layer pattern surrounded by the outer front layer pattern. The inner front layer pattern is square in shape. The outer front layer pattern includes a central square region and a first straight line segment extending outward from the four sides of the square region. The plurality of current layer patterns include an outer current layer pattern and an inner current layer pattern surrounded by the outer current layer pattern. The inner current layer pattern is square in shape. The outer current layer pattern includes a central square region and a second straight line segment extending outward from the four sides of the square region. Measure the key dimensions of the current layer pattern, and simultaneously measure the overprinting error between the current layer pattern and the previous layer pattern.
8. The measurement method according to claim 7, characterized in that, Measuring the key dimensions of the current layer graphic includes measuring the key dimensions of dense line areas and measuring the key dimensions of isolated line areas.
9. The measurement method according to claim 7, characterized in that, The overprinting error includes overprinting error in a first direction and overprinting error in a second direction, wherein the first direction and the second direction are located in the plane of the mask and are perpendicular to each other.
10. The measurement method according to claim 7, characterized in that, The key dimensions of the current graphic are measured using a first measuring device, and the overprinting error between the current graphic and the previous graphic is measured using a second measuring device.