High contrast quartz wafer alignment mark and method of making same

Abstract

The application discloses a high-contrast quartz wafer alignment mark and a manufacturing method thereof. The alignment mark is a cross-shaped alignment mark, and the alignment mark comprises vertical marks and horizontal marks located on both sides of the vertical marks. The vertical marks and the horizontal marks both comprise photosensitive structures. The photosensitive structure of the vertical mark comprises a plurality of photosensitive triangles with consistent arrangement directions. The photosensitive structure of the horizontal mark comprises a plurality of photosensitive triangles, and the arrangement directions of the photosensitive triangles of the horizontal marks located on both sides of the vertical mark are opposite. The high-contrast quartz wafer alignment mark and the manufacturing method thereof provided by the application do not need to adjust and reform existing proximity photolithography equipment, and effectively improve the contrast of the edge morphology of the alignment mark.

Description

Technical Field

[0001] This invention relates to the field of piezoelectric quartz wafers, and more specifically to a high-contrast quartz wafer alignment mark and its fabrication method. Background Technology

[0002] Currently, in the quartz crystal industry, there are five main types of alignment marks used in proximity lithography machines: (1) L-shaped mark: It consists of two mutually perpendicular strips, one of which is the longer "main axis" and the other is the shorter "secondary axis". It is generally used for alignment of larger areas of photoresist.

[0003] (2) T-shaped mark: consisting of a long strip and a short strip, generally used for local alignment.

[0004] (3) Diagonal mark: A slanted line, suitable for very small local alignments.

[0005] (4) Square mark: It is generally composed of four lines of equal length and is suitable for positioning or full alignment of photoresist.

[0006] (5) Cross-shaped mark: It consists of two long strips of equal length that are perpendicular to each other. It is suitable for positioning or full alignment of photoresist.

[0007] For quartz wafers, the crystal structure and cutting orientation affect their response to wet etching in different directions. During wet etching, the surface of the quartz crystal is more easily dissolved in certain directions, resulting in anisotropy in the wet etching process (e.g., for AT-type quartz wafers). Under these conditions, the alignment marks used for photolithography will exhibit irregular morphology at symmetrical positions on the left and right edges or top and bottom edges after etching, leading to poor contrast of the alignment marks and reducing the alignment accuracy of the proximity lithography machine.

[0008] The applicant has discovered that the prior art has at least the following technical problems: In existing technologies, alignment marks exhibit irregular morphology at symmetrical positions on the left and right edges or top and bottom edges after etching, resulting in poor contrast of the alignment marks and reducing the alignment accuracy of proximity lithography machines. Summary of the Invention

[0009] The purpose of this invention is to provide a high-contrast alignment mark for quartz wafers and a method for manufacturing the same, thereby solving the technical problems in the prior art. The various technical effects of the preferred solutions among the many technical solutions provided by this invention are detailed below.

[0010] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a high-contrast alignment mark for a quartz wafer. The alignment mark is a cross-shaped mark, characterized in that it includes a vertical mark and horizontal marks located on either side of the vertical mark, both of which include photosensitive structures; wherein, The photosensitive structure of the vertical mark includes several photosensitive isosceles triangles arranged in the same direction; The photosensitive structure of the horizontal mark includes several photosensitive isosceles triangles, and the photosensitive isosceles triangles of the horizontal mark located on both sides of the vertical mark are arranged in opposite directions. The distance between the vertically marked photosensitive isosceles triangle and the horizontally marked photosensitive isosceles triangles on both sides is K0, where K0 ≥ 50 μm; The angle of the vertex of the photosensitive isosceles triangle of the vertical and horizontal markings is K1, where K1 is 10º-60º; The etching width of the photosensitive isosceles triangles of the vertical and horizontal markings is K2, where K2 ≥ 10 μm; The distance between adjacent photosensitive isosceles triangles of the vertical marking and the distance between adjacent photosensitive isosceles triangles of the horizontal marking are both K3, where K3 ≥ 5.5 μm.

[0011] Furthermore, the photosensitive structures of the horizontal and vertical marks are both photosensitive isosceles triangles of the same size.

[0012] Furthermore, the photosensitive structure of the vertical marking includes 1-3 columns of photosensitive isosceles triangles arranged in the same direction.

[0013] Furthermore, the photosensitive structure of the vertical mark includes two columns of photosensitive isosceles triangles arranged in the same direction; Furthermore, the photosensitive structures of the horizontal marks located on both sides of the vertical marks all include 1-3 columns of photosensitive isosceles triangles arranged in the same direction.

[0014] Furthermore, the photosensitive structures of the horizontal marks located on both sides of the vertical marks each consist of two rows of photosensitive isosceles triangles arranged in the same direction.

[0015] Furthermore, 50um≤K0≤70um; K1 is 20º-40º; 10um≤K2≤20um; 5.5um≤K3≤10um.

[0016] Furthermore, K0 = 60µm; K1 = 30µm; K2 = 15µm; K3 = 7.5µm.

[0017] The present invention provides a method for fabricating high-contrast quartz wafer alignment marks. A mask is fabricated according to the alignment marks designed in the above-mentioned high-contrast quartz wafer alignment marks. Then, a metal film is deposited on the quartz wafer, and photolithography, metal etching and wafer etching thinning processes are performed. The mark finally etched out is the quartz wafer alignment mark.

[0018] Based on the above technical solution, the embodiments of the present invention can produce at least the following technical effects: This invention provides a high-contrast quartz wafer alignment mark and its fabrication method. The alignment mark can be placed on the front or back of the wafer and, after photolithography, metal etching, and wafer thinning processes, is finally used in the next photolithography alignment process. The high-contrast quartz wafer alignment mark designed in this invention can be used to fabricate alignment marks for products with different etching depths by adjusting the lateral spacing, V-angle, etching width, and light-shielding spacing. In practical applications, using the quartz photolithography alignment mark provided by this invention eliminates the need for adjustments and modifications to existing proximity lithography equipment. After etching, the alignment mark exhibits no irregular morphology at its symmetrical positions on the left and right edges and top and bottom edges, effectively improving the contrast of the alignment mark's edge morphology and enhancing the alignment accuracy of the proximity lithography machine. Furthermore, the structure of the alignment mark in this invention is also applicable to alignment marks for other anisotropic etching processes, such as square and T-shaped marks. By adjusting the angle and distance of the triangles according to the material's etching characteristics, stable and high-contrast alignment marks can also be obtained. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 These are schematic diagrams of the alignment marks in Embodiments 1, 2, 4, and 7 of the present invention; Figure 2 These are schematic diagrams of the alignment marks in Embodiments 2 and 6 of the present invention; Figure 3 These are schematic diagrams of the alignment marks in Embodiments 5 and 8 of the present invention; Figure 4 This is an application effect diagram of the alignment mark after etching in Embodiment 1 of the present invention; Figure 5 This is an application effect diagram of the alignment mark after etching in Embodiment 2 of the present invention; Figure 6This is an application effect diagram of the alignment mark after etching in Embodiment 3 of the present invention; Figure 7 This is an application effect diagram of the alignment mark after etching in Embodiment 4 of the present invention; Figure 8 This is an application effect diagram of the alignment mark after etching in Embodiment 5 of the present invention; Figure 9 This is an application effect diagram of the alignment mark after etching in Embodiment 6 of the present invention; Figure 10 This is an application effect diagram of the alignment mark after etching in Embodiment 7 of the present invention; Figure 11 This is an application effect diagram of the alignment mark after etching in Embodiment 8 of the present invention; Figure 12 This is a schematic diagram of the alignment marks in Comparative Example 1; Figure 13 This is an application effect diagram of the alignment mark after erosion in Comparative Example 1.

[0021] In the diagram: 1. Vertical markings; 2. Horizontal markings. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0023] I. Example: like Figures 1-11 As shown: This invention provides a high-contrast alignment mark for a quartz wafer. The alignment mark is a cross-shaped mark, characterized in that it includes a vertical mark and horizontal marks located on either side of the vertical mark, both of which include photosensitive structures; wherein, The photosensitive structure of the vertical mark includes several photosensitive isosceles triangles arranged in the same direction; The photosensitive structure of the horizontal mark includes several photosensitive isosceles triangles, and the photosensitive isosceles triangles of the horizontal mark located on both sides of the vertical mark are arranged in opposite directions. The distance between the vertically marked photosensitive isosceles triangle and the horizontally marked photosensitive isosceles triangles on both sides is K0, where K0 ≥ 50 μm; The angle of the vertex of the photosensitive isosceles triangle of the vertical and horizontal markings is K1, where K1 is 10º-60º; The etching width of the photosensitive isosceles triangles of the vertical and horizontal markings is K2, where K2 ≥ 10 μm; The distance between adjacent photosensitive isosceles triangles of the vertical mark (i.e., the shading distance) and the distance between adjacent photosensitive isosceles triangles of the horizontal mark (i.e., the shading distance) are both K3, where K3 ≥ 5.5 μm.

[0024] This invention provides a high-contrast quartz wafer alignment mark and its fabrication method. The alignment mark can be placed on the front or back of the wafer and, after photolithography, metal etching, and wafer thinning processes, is finally used in the next photolithography alignment process. The high-contrast quartz wafer alignment mark designed in this invention can be used to fabricate alignment marks for products with different etching depths by adjusting the lateral spacing, V-angle, etching width, and light-shielding spacing. In practical applications, using the quartz photolithography alignment mark provided by this invention eliminates the need for adjustments and modifications to existing proximity lithography equipment. After etching, the alignment mark exhibits no irregular morphology at its symmetrical positions on the left and right edges and top and bottom edges, effectively improving the contrast of the alignment mark's edge morphology and enhancing the alignment accuracy of the proximity lithography machine. Furthermore, the structure of the alignment mark in this invention is also applicable to alignment marks for other anisotropic etching processes, such as square and T-shaped marks. By adjusting the angle and distance of the triangles according to the material's etching characteristics, stable and high-contrast alignment marks can also be obtained.

[0025] Furthermore, the photosensitive structures of the horizontal and vertical marks are both photosensitive isosceles triangles of the same size.

[0026] Furthermore, the photosensitive structure of the vertical marking includes 1-3 columns of photosensitive isosceles triangles arranged in the same direction.

[0027] Furthermore, the photosensitive structure of the vertical mark includes two columns of photosensitive isosceles triangles arranged in the same direction; Furthermore, the photosensitive structures of the horizontal marks located on both sides of the vertical marks all include 1-3 columns of photosensitive isosceles triangles arranged in the same direction.

[0028] Furthermore, the photosensitive structures of the horizontal marks located on both sides of the vertical marks each consist of two rows of photosensitive isosceles triangles arranged in the same direction.

[0029] Furthermore, 50um≤K0≤70um; K1 is 20º-40º; 10um≤K2≤20um; 5.5um≤K3≤10um.

[0030] Furthermore, K0 = 60µm; K1 = 30µm; K2 = 15µm; K3 = 7.5µm.

[0031] The parameters of the alignment marks in Examples 1-8 are shown in Table 1 below: Table 1 Alignment Mark Parameter Table for Examples and Comparative Examples II. Experimental Example: Using the alignment marks in the prior art as a comparative example 1, such as Figure 12 The diagram shown is a schematic diagram of the alignment mark in the prior art. The etching width of the alignment mark is 7 μm and the etching depth is 80 μm.

[0032] The alignment marks designed in Examples 1-8 and Comparative Example 1 are used to fabricate a photomask. A metal film is then deposited on a quartz wafer, followed by photolithography, metal etching, and wafer thinning processes. The resulting etched marks are the alignment marks for the quartz wafer. The etching effect is shown in the figure below. Figures 4-11 as well as Figure 13 As shown.

[0033] like Figures 4-11 As shown, the etching effect diagrams of the alignment marks in Embodiments 1-8 of the present invention are shown. It can be seen that in the embodiments of the present invention, the alignment marks do not have irregular morphologies at the symmetrical positions of the left and right edges and the top and bottom edges after etching, which effectively improves the contrast of the edge morphology of the alignment marks and improves the alignment accuracy of the proximity lithography machine. Figure 13 As shown, this is an image of the etching effect of the alignment mark in Comparative Example 1. After etching, the alignment mark in Comparative Example 1 has irregular morphology at the symmetrical positions of the left and right edges and the top and bottom edges, which reduces the contrast of the edge morphology of the alignment mark.

[0034] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-contrast alignment mark for a quartz wafer, wherein the alignment mark is a cross-shaped alignment mark, characterized in that, The alignment marks include vertical marks and horizontal marks located on both sides of the vertical marks, and both the vertical and horizontal marks include photosensitive structures; wherein, The photosensitive structure of the vertical mark includes several photosensitive isosceles triangles arranged in the same direction; The photosensitive structure of the horizontal mark includes several photosensitive isosceles triangles, and the photosensitive isosceles triangles of the horizontal mark located on both sides of the vertical mark are arranged in opposite directions. The distance between the vertically marked photosensitive isosceles triangle and the horizontally marked photosensitive isosceles triangles on both sides is K0, where K0 ≥ 50 μm; The angle of the vertex of the photosensitive isosceles triangle of the vertical and horizontal markings is K1, where K1 is 10º-60º; The etching width of the photosensitive isosceles triangles of the vertical and horizontal markings is K2, where K2 ≥ 10 μm; The distance between adjacent photosensitive isosceles triangles of the vertical marking and the distance between adjacent photosensitive isosceles triangles of the horizontal marking are both K3, where K3 ≥ 5.5 μm.

2. The high-contrast quartz wafer alignment mark according to claim 1, characterized in that, The photosensitive structures of both the horizontal and vertical markings are photosensitive isosceles triangles of the same size.

3. The high-contrast quartz wafer alignment mark according to claim 1, characterized in that, The photosensitive structure of the vertical marker consists of 1-3 columns of photosensitive isosceles triangles arranged in the same direction.

4. The high-contrast quartz wafer alignment mark according to claim 3, characterized in that, The photosensitive structure of the vertical marker consists of two rows of photosensitive isosceles triangles arranged in the same direction.

5. The high-contrast quartz wafer alignment mark according to claim 1, characterized in that, The photosensitive structures of the horizontal marks located on both sides of the vertical mark all consist of 1-3 rows of photosensitive isosceles triangles arranged in the same direction.

6. The high-contrast quartz wafer alignment mark according to claim 5, characterized in that, The photosensitive structures of the horizontal marks located on both sides of the vertical mark each consist of two rows of photosensitive isosceles triangles arranged in the same direction.

7. The high-contrast quartz wafer alignment mark according to any one of claims 1-6, characterized in that, 50um≤K0≤70um; K1 is 20º-40º; 10um≤K2≤20um; 5.5um≤K3≤10um.

8. The high-contrast quartz wafer alignment mark according to any one of claims 1-6, characterized in that, K0 = 60um; K1 is 30º; K2 = 15um; K3 = 7.5um.

9. A method for fabricating high-contrast alignment marks on a quartz wafer, characterized in that, A photomask is made by designing alignment marks according to any one of claims 1-8 for high-contrast quartz wafer alignment marks. Then, a metal film is deposited on the quartz wafer, and photolithography, metal etching and wafer etching thinning processes are performed. The finally etched mark is the quartz wafer alignment mark.

Images