Lithography method for reducing distortion of three-dimensional pattern lithography

Abstract

The present invention provides a photolithography method for reducing distortion in stereolithography, comprising: 1) providing a substrate having a concave terrace structure on its surface; 2) forming a photoresist layer on the substrate surface, the sidewalls, and the bottom of the concave terrace structure; 3) providing a photomask comprising a light-transmitting substrate and a mask pattern layer, and forming an anti-reflection layer on the mask pattern layer; 4) exposing the photoresist layer using the photomask, wherein the mask pattern layer at least shields the photoresist layer at the bottom of the concave terrace structure and at least exposes the photoresist layer at the sidewalls of the concave terrace structure; and 5) developing the photoresist layer. The present invention effectively solves the problem of light reflection at the photomask interface during contact exposure of stereolithography, thereby preserving the fidelity of the photolithography pattern.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor manufacturing and relates to the field of photolithography technology, and in particular to a photolithography method for reducing photolithography distortion of three-dimensional patterns. Background Art

[0002] Spray coating is widely used in semiconductor integrated circuits. When wafers with highly undulating topography require a uniform coating of photoresist, spray coating is essential. Compared to traditional spin coating techniques, spray coating offers significant advantages for wafers with high step heights. Contact exposure is widely used in semiconductor integrated circuit manufacturing, generally for layers with larger line widths. Reflection exists at any interface and can occur at these interfaces.

[0003] This reflection phenomenon easily causes the non-exposed areas to be exposed to the exposure light, thereby affecting the exposure accuracy and ultimately causing distortion of the photolithography pattern.

[0004] It should be noted that the above introduction to the technical background is merely intended to provide a clear and complete description of the technical solutions of this application and facilitate understanding by those skilled in the art. Simply because these solutions are described in the background technology section of this application, it should not be assumed that the above technical solutions are well known to those skilled in the art. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a lithography method for reducing distortion of stereographic patterns, so as to solve the problem of distortion of lithographic patterns caused by reflected light in the prior art stereographic pattern lithography process.

[0006] To achieve the above-mentioned object and other related objects, the present invention provides a photolithography method for reducing the distortion of three-dimensional pattern lithography, the photolithography method comprising: 1) providing a substrate, the surface of the substrate having a concave terrace structure; 2) forming a photoresist layer on the surface of the substrate, the sidewalls and the bottom of the concave terrace structure; 3) providing a photomask, the photomask comprising a light-transmitting substrate and a mask pattern layer, and forming an anti-reflection layer on the mask pattern layer; 4) exposing the photoresist layer based on the photomask, the mask pattern layer at least shielding a portion of the photoresist layer at the bottom of the concave terrace structure and at least exposing a portion of the photoresist layer on the sidewalls of the concave terrace structure; and 5) developing the photoresist layer.

[0007] Optionally, an angle between a side wall of the concave platform structure and a bottom of the concave platform structure is an obtuse angle, and the obtuse angle is 95 to 150 degrees.

[0008] Optionally, the anti-reflection layer faces the bottom of the concave platform structure. During the exposure process, when vertically incident exposure light irradiates the photoresist layer on the side wall of the concave platform structure and is reflected to form reflected light, the reflected light reaches the photomask and is absorbed by the anti-reflection layer.

[0009] Optionally, in step 3), the inorganic anti-reflection layer is formed on the mask pattern layer by a chemical vapor deposition process.

[0010] Optionally, the anti-reflection layer is an inorganic anti-reflection layer, and a material of the inorganic anti-reflection layer includes one of silicon nitride, silicon oxide, silicon oxynitride, amorphous carbon and titanium nitride.

[0011] Optionally, the anti-reflection layer has a thickness of 30 nm to 50 nm.

[0012] Optionally, in step 4), the photoresist layer is exposed using a contact exposure process.

[0013] Optionally, in step 2), a spray coating process is used to form the photoresist layer on the surface of the substrate, the sidewalls and the bottom of the concave platform structure.

[0014] Optionally, the photoresist layer is a negative photoresist.

[0015] Optionally, the light-transmitting substrate includes a quartz substrate, and the mask pattern layer includes metallic chromium or a metallic chromium compound.

[0016] As described above, the lithography method of the present invention for reducing lithography distortion of three-dimensional patterns has the following beneficial effects:

[0017] The present invention is directed to a three-dimensional pattern substrate having a concave terrace structure on its surface. By forming an anti-reflection layer on the mask pattern layer, when vertically incident exposure light irradiates the photoresist layer on the side wall of the concave terrace structure and is reflected to form reflected light, the reflected light can be absorbed by the anti-reflection layer after reaching the photomask without generating secondary reflected light, thereby solving the problem of light reflected from the photomask interface during contact exposure of the three-dimensional pattern, thereby preserving the fidelity of the photolithographic pattern. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are included to provide a further understanding of the embodiments of the present application, and constitute a part of the specification, and are used to illustrate the implementation of the present application and, together with the text description, to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application.

[0019] Figures 1 and 2 A schematic diagram showing a photolithography process in which light reflection causes non-exposed areas to be exposed to light, resulting in photoresist residue.

[0020] Figures 3 to 7 Shown is a structural schematic diagram of various steps of a photolithography method for reducing photolithography distortion of a three-dimensional pattern according to an embodiment of the present invention.

[0021] Component number description

[0022] 101 Wafer

[0023] 102 Photoresist

[0024] 103 Photomask

[0025] 104 Reflected Light

[0026] 105 Photoresist residue

[0027] 201 base

[0028] 202 concave platform structure

[0029] 203 Sidewall of concave platform structure

[0030] 204 Bottom of concave platform structure

[0031] 205 photoresist layer

[0032] 206 Transparent Substrate

[0033] 207 mask pattern layer

[0034] 208 anti-reflective layer

[0035] 209 Lithography Window DETAILED DESCRIPTION

[0036] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0037] It should be emphasized that the term "include / comprising" when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps or components.

[0038] Features described and / or illustrated with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

[0039] For example, when describing the embodiments of the present invention, cross-sectional views of device structures may be partially enlarged to scale for ease of explanation. Furthermore, these schematic views are merely illustrative and should not limit the scope of the present invention. Furthermore, in actual manufacturing, three-dimensional dimensions, including length, width, and depth, should be included.

[0040] For convenience, spatially relative terms such as "under," "below," "below," "below," "above," and "on" may be used herein to describe the relationship of one element or feature to other elements or features shown in the drawings. It will be understood that these spatially relative terms are intended to encompass orientations of the device in use or operation in addition to the orientation depicted in the drawings. Additionally, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.

[0041] In the context of the present application, a structure described as a first feature being "above" a second feature may include embodiments where the first and second features are formed in direct contact, and may also include embodiments where an additional feature is formed between the first and second features, such that the first and second features may not be in direct contact.

[0042] It should be noted that the illustrations provided in this embodiment are only used to schematically illustrate the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0043] like Figure 1 As shown, in the spray coating photolithography process, it is often encountered that after the wafer 101 undergoes KOH (potassium hydroxide) corrosion, physical vapor deposition (PVD) metal and other processes, a concave platform structure will be formed on the surface of the wafer, and then the spray coating photolithography process is performed. After the photoresist 102 is coated on the spray coating machine, it is exposed through the photomask 103 in the exposure machine. During exposure, due to the light reflection of the slope mirror surface of the product structure, part of the light is reflected to the back interface of the mask and then forms reflected light 104 onto the wafer. This phenomenon causes the photoresist in the non-exposed area to be exposed due to contact with the reflected light, resulting in distortion of the photolithography pattern, and the bottom photoresist is irradiated by ultraviolet light, resulting in photoresist residue 105, as shown Figure 2 shown.

[0044] In order to solve the above problems, Figures 3 to 7 As shown, this embodiment provides a lithography method for reducing lithography distortion of three-dimensional patterns, the lithography method comprising:

[0045] like Figure 3As shown, step 1) is first performed to provide a substrate 201 , wherein the surface of the substrate 201 has a concave platform structure 202 .

[0046] In one embodiment, the substrate 201 may be a silicon substrate, a germanium substrate, a germanium silicon substrate, a III-V compound substrate, an insulating substrate (such as silicon dioxide, sapphire, etc.), or a stack of two or more of the above substrates.

[0047] The angle α between the sidewall 203 of the concave terrace structure 202 and the bottom 204 of the concave terrace structure 202 is an obtuse angle, and the angle of the obtuse angle is between 95 and 150 degrees. For example, the obtuse angle can be 95 degrees, 100 degrees, 120 degrees, 135 degrees, 150 degrees, etc., and can be adjusted based on actual structural requirements and the type of etching process, and is not limited to the examples listed above. The surface of the concave terrace structure 202 can expose the substrate 201, or it can be formed with other material layers, such as a metal layer, an insulating layer, a semiconductor layer, etc.

[0048] like Figure 4 As shown, step 2) is then performed to form a photoresist layer 205 on the surface of the substrate 201 , the sidewalls 203 and the bottom 204 of the concave platform structure 202 .

[0049] In one embodiment, step 2) uses a spray coating process to form the photoresist layer 205 on the surface of the substrate 201 and the sidewalls 203 and bottom 204 of the concave terrace structure 202. The spray coating process can effectively form a photoresist layer 205 with a uniform thickness within the concave terrace structure 202, and can effectively control the thickness of the photoresist layer 205.

[0050] In one embodiment, the photoresist layer 205 is a negative photoresist.

[0051] like Figure 5 As shown, step 3) is then performed to provide a photomask, which includes a transparent substrate 201 and a mask pattern layer 207 , and an anti-reflection layer 208 is formed on the mask pattern layer 207 .

[0052] In one embodiment, the transparent substrate 206 includes a quartz substrate with a light transmittance greater than 80%, and the mask pattern layer 207 includes metal chromium or a metal chromium compound.

[0053] In one embodiment, step 3) forms the inorganic anti-reflection layer on the mask pattern layer 207 by a chemical vapor deposition process.

[0054] In one embodiment, the anti-reflective layer 208 is an inorganic anti-reflective layer, and the material of the inorganic anti-reflective layer includes one of silicon nitride, silicon oxide, silicon oxynitride, amorphous carbon, and titanium nitride. The anti-reflective layer 208 of the present invention is an inorganic anti-reflective layer, which has high density and pressure resistance, thereby preventing debris from being generated when in contact with the photomask. During the exposure process, reflected light is absorbed by the anti-reflective layer 208 on the photomask, ensuring that the photolithographic pattern is intact. During the exposure process, reflected light is absorbed by the anti-reflective layer 208 on the photomask, ensuring that the photolithographic pattern is intact.

[0055] In one embodiment, the thickness of the anti-reflection layer 208 is 30 nanometers to 50 nanometers. For example, the thickness of the anti-reflection layer 208 may be 40 nanometers.

[0056] like Figure 6 As shown, step 4 is then performed, wherein the photoresist layer 205 is exposed based on the photomask, wherein the mask pattern layer 207 at least blocks a portion of the photoresist layer 205 at the bottom 204 of the concave platform structure 202 and at least exposes a portion of the photoresist layer 205 at the sidewall 203 of the concave platform structure 202;

[0057] In one embodiment, the mask pattern layer 207 blocks a portion of the photoresist layer 205 in the middle region of the bottom 204 of the concave mesa structure 202 and exposes the entire photoresist layer 205 on the sidewalls 203 of the concave mesa structure 202 .

[0058] In one embodiment, step 4) uses a contact exposure process to expose the photoresist layer 205 .

[0059] In one embodiment, the anti-reflection layer 208 faces the bottom 204 of the concave platform structure 202. During the exposure process, when vertically incident exposure light irradiates the photoresist layer 205 on the sidewall 203 of the concave platform structure 202 and is reflected to form reflected light, the reflected light reaches the photomask and is absorbed by the anti-reflection layer 208.

[0060] like Figure 7 As shown, step 5) is finally performed to develop the photoresist layer 205.

[0061] In one embodiment, the photoresist layer 205 is developed by a wet process, and the exposed photoresist layer 205 is placed in a developer to remove the photoresist layer 205 that has not been exposed to the exposure light, thereby forming a photolithography window 209. The present invention absorbs the reflected light through the anti-reflection layer 208, so that the area blocked by the mask pattern layer 207 will not be affected by the reflected light, so that no photoresist layer 205 remains in the photolithography window 209 after development, thereby improving the accuracy of the photolithography process and preserving the fidelity of the formed photolithography pattern.

[0062] As described above, the lithography method of the present invention for reducing lithography distortion of three-dimensional patterns has the following beneficial effects:

[0063] The present invention is directed to a three-dimensional pattern substrate 201 having a concave terrace structure 202 on its surface. By forming an anti-reflection layer 208 on the mask pattern layer 207, when vertically incident exposure light irradiates the photoresist layer 205 on the sidewall 203 of the concave terrace structure 202 and is reflected to form reflected light, the reflected light can be absorbed by the anti-reflection layer 208 after reaching the photomask without generating secondary reflected light, thereby solving the problem of light reflected from the photomask interface during contact exposure of the three-dimensional pattern, thereby preserving the fidelity of the photolithographic pattern.

[0064] Therefore, the present invention effectively overcomes various shortcomings of the prior art and has high industrial utilization value.

[0065] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A lithography method for reducing lithography distortion of a three-dimensional pattern, characterized in that: The photolithography method comprises: 1) Providing a substrate, wherein a surface of the substrate has a concave platform structure, wherein the angle between the sidewall of the concave platform structure and the bottom of the concave platform structure is an obtuse angle, and the angle of the obtuse angle is 95 to 150 degrees; 2) forming a photoresist layer on the surface of the substrate, the sidewalls and the bottom of the concave mesa structure; 3) providing a photomask, the photomask comprising a light-transmitting substrate and a mask pattern layer, and forming an anti-reflection layer on the mask pattern layer; 4) performing an exposure process on the photoresist layer based on the photomask, wherein the mask pattern layer at least shields a portion of the photoresist layer at the bottom of the concave mesa structure and at least exposes a portion of the photoresist layer on the sidewall of the concave mesa structure; 5) Performing a development process on the photoresist layer.

2. The photolithography method for reducing lithography distortion of three-dimensional patterns according to claim 1, characterized in that: The anti-reflection layer faces the bottom of the concave platform structure. During the exposure process, when vertically incident exposure light irradiates the photoresist layer on the side wall of the concave platform structure and is reflected to form reflected light, the reflected light reaches the photomask and is absorbed by the anti-reflection layer.

3. The photolithography method for reducing distortion in 3D patterning according to claim 1, wherein: Step 3) forming the anti-reflection layer on the mask pattern layer by a chemical vapor deposition process.

4. The photolithography method for reducing lithography distortion of three-dimensional patterns according to claim 1, wherein: The anti-reflection layer is an inorganic anti-reflection layer, and a material of the inorganic anti-reflection layer includes one of silicon nitride, silicon oxide, silicon oxynitride, amorphous carbon and titanium nitride.

5. The photolithography method for reducing lithography distortion of three-dimensional patterns according to claim 1, wherein: The thickness of the anti-reflection layer is 30 nanometers to 50 nanometers.

6. The photolithography method for reducing lithography distortion of three-dimensional patterns according to claim 1, wherein: Step 4) exposing the photoresist layer using a contact exposure process.

7. The photolithography method for reducing lithography distortion of three-dimensional patterns according to claim 1, wherein: Step 2) forming the photoresist layer on the surface of the substrate, the sidewalls and the bottom of the concave platform structure by a spray coating process.

8. The photolithography method for reducing lithography distortion of three-dimensional patterns according to claim 1, wherein: The photoresist layer is a negative photoresist.

9. The photolithography method for reducing lithography distortion of three-dimensional patterns according to claim 1, characterized in that: The light-transmitting substrate includes a quartz substrate, and the mask pattern layer includes metal chromium or a metal chromium compound.

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