CN113394198A - Photoetching alignment mark and forming method thereof - Google Patents
Photoetching alignment mark and forming method thereof Download PDFInfo
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- CN113394198A CN113394198A CN202110617458.1A CN202110617458A CN113394198A CN 113394198 A CN113394198 A CN 113394198A CN 202110617458 A CN202110617458 A CN 202110617458A CN 113394198 A CN113394198 A CN 113394198A
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- alignment mark
- photoresist layer
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- groove
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/544—Marks applied to semiconductor devices or parts, e.g. registration marks, alignment structures, wafer maps
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
- G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
- G03F9/7073—Alignment marks and their environment
- G03F9/708—Mark formation
Abstract
The invention provides a photoetching alignment mark and a forming method thereof, wherein the forming method comprises the following steps: providing a substrate, and coating a first photoresist layer on the substrate; etching the first photoresist layer to form a groove on the substrate; removing the first photoresist layer remained on the substrate, and coating a second photoresist layer on the substrate to enable the second photoresist layer to cover the groove; and etching the second photoresist layer, and forming an alignment mark in the groove, wherein the alignment mark comprises four same strip-shaped patterns, so that the ratio of the sum of the depth of the groove and the thickness of the second photoresist layer at the periphery of the groove to the width of the strip-shaped patterns is smaller than a design value. By strictly controlling the aspect ratio of the alignment mark, the environment where the alignment mark is located is improved, and the problem that the alignment mark collapses due to the overlarge aspect ratio is avoided.
Description
Technical Field
The invention belongs to the technical field of semiconductor manufacturing, and particularly relates to a photoetching alignment mark and a forming method thereof.
Background
BSI (backside illuminated image sensor) is a technique that transfers a circuit portion originally located between a lens and a photosensitive semiconductor to the periphery or under the photosensitive semiconductor on the basis of a conventional image sensor technology, so that light can directly enter the photosensitive semiconductor, reflection is reduced, and lighting efficiency is greatly improved. In the BSI process, the photoetching alignment mark is placed at a special position, the photoetching alignment mark is usually placed in a groove, the groove is formed by etching photoresist, and the setting environment of the photoetching alignment mark is poor easily because the profile of the photoresist in the groove is uneven and is in a downhill shape. Moreover, if the pattern of the photolithography alignment mark is linear, the photolithography alignment mark is likely to collapse due to the influence of a large aspect ratio when the trench is deep.
Disclosure of Invention
The invention aims to provide a photoetching alignment mark and a forming method thereof, which can improve the environment of the alignment mark and avoid the problem of collapse of the alignment mark due to overlarge depth-to-width ratio.
In order to achieve the above object, the present invention provides a method for forming a photolithography alignment mark, comprising the steps of:
providing a substrate, and coating a first photoresist layer on the substrate;
etching the first photoresist layer to form a groove on the substrate;
removing the first photoresist layer remained on the substrate, and coating a second photoresist layer on the substrate to enable the second photoresist layer to cover the groove;
and etching the second photoresist layer, and forming an alignment mark in the groove, wherein the alignment mark comprises four same strip-shaped patterns, so that the ratio of the sum of the depth of the groove and the thickness of the second photoresist layer at the periphery of the groove to the width of the strip-shaped patterns is smaller than a design value.
Alternatively, the design value is 2.
Optionally, the alignment mark includes two first bar patterns arranged along an X direction and two second bar patterns arranged along a Y direction, the first bar patterns and the second bar patterns are completely the same, and the two first bar patterns and the two second bar patterns are both arranged symmetrically with respect to a center of the alignment mark.
Optionally, a first gap is provided between an outer boundary of the first stripe pattern and a boundary of the trench.
Optionally, the first gap is not less than 5 microns.
Optionally, a second gap is formed between an outer boundary of the second stripe pattern and a boundary of the trench.
Optionally, the second gap is not less than 30 microns.
Optionally, the alignment mark is located at the very center of the groove.
Optionally, the substrate is made of aluminum.
Based on the structure, the invention also provides a photoetching alignment mark which is formed by adopting the forming method of the photoetching alignment mark.
In the lithography alignment mark and the forming method thereof provided by the invention, the forming method comprises the following steps: providing a substrate, and coating a first photoresist layer on the substrate; etching the first photoresist layer to form a groove on the substrate; removing the first photoresist layer remained on the substrate, and coating a second photoresist layer on the substrate to enable the second photoresist layer to cover the groove; and etching the second photoresist layer, and forming an alignment mark in the groove, wherein the alignment mark comprises four same strip-shaped patterns, so that the ratio of the sum of the depth of the groove and the thickness of the second photoresist layer at the periphery of the groove to the width of the strip-shaped patterns is smaller than a design value. The depth-to-width ratio of the alignment mark is strictly controlled by enabling the ratio of the sum of the depth of the groove and the thickness of the second photoresist layer at the periphery of the groove to the width of the strip-shaped pattern to be smaller than a design value, so that the environment where the alignment mark is located is improved, and the problem that the alignment mark collapses due to the fact that the depth-to-width ratio is too large is avoided.
Drawings
It will be appreciated by those skilled in the art that the drawings are provided for a better understanding of the invention and do not constitute any limitation to the scope of the invention. Wherein:
FIG. 1 is a flowchart illustrating a method for forming a photolithography alignment mark according to the present embodiment;
FIG. 2 is a schematic diagram of a photolithography alignment mark and a trench provided in the present embodiment;
FIG. 3 is a diagram illustrating a pre-layer alignment mark and a current layer alignment mark provided in the present embodiment;
wherein the reference numerals are:
10-front layer alignment mark; 20-current layer alignment mark; 30-a trench;
110-a first striped pattern; 120-a second bar pattern;
d-the width of the bar pattern; h 1-first gap; h2 — second gap.
Detailed Description
As described in the background, the lithographic alignment marks placed in the trenches are placed in a poor environment. Moreover, if the pattern of the photolithography alignment mark is linear, when the trench is deep, the photolithography alignment mark is likely to collapse due to the influence of a large aspect ratio.
Therefore, the invention provides a photoetching alignment mark and a forming method thereof, which can improve the environment of the alignment mark and avoid the problem of collapse of the alignment mark due to overlarge depth-to-width ratio.
To further clarify the objects, advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is to be noted that the drawings are in greatly simplified form and are not to scale, but are merely intended to facilitate and clarify the explanation of the embodiments of the present invention. Further, the structures illustrated in the drawings are often part of actual structures. In particular, the drawings may have different emphasis points and may sometimes be scaled differently. It should be further understood that the terms "first," "second," "third," and the like in the description are used for distinguishing between various components, elements, steps, and the like, and are not intended to imply a logical or sequential relationship between various components, elements, steps, or the like, unless otherwise indicated or indicated.
Referring to fig. 1, fig. 1 is a flowchart illustrating a method for forming a photolithography alignment mark according to the present embodiment. The embodiment provides a method for forming a photoetching alignment mark, which comprises the following steps:
s1, providing a substrate, and coating a first photoresist layer on the substrate;
s2, etching the first photoresist layer to form a groove on the substrate;
s3, removing the first photoresist layer remained on the substrate, and coating a second photoresist layer on the substrate to enable the second photoresist layer to cover the groove;
and S4, etching the second photoresist layer, and forming an alignment mark in the groove, wherein the alignment mark comprises four same strip-shaped patterns, and the ratio of the sum of the depth of the groove and the thickness of the second photoresist layer at the periphery of the groove to the width of the strip-shaped patterns is smaller than a design value.
The depth-to-width ratio of the alignment mark is strictly controlled by enabling the ratio of the sum of the depth of the groove and the thickness of the second photoresist layer at the periphery of the groove to the width of the strip-shaped pattern to be smaller than a design value, so that the environment where the alignment mark is located is improved, and the problem that the alignment mark collapses due to the fact that the depth-to-width ratio is too large is avoided.
Specifically, step S1 is performed to provide a substrate, and a first photoresist layer is coated on the substrate. In this embodiment, the substrate is mainly used for forming a back-illuminated image sensor, and the substrate is, for example, an aluminum substrate. However, in other embodiments, the substrate may also be a Germanium substrate, a Silicon Germanium substrate, an SOI (Silicon On Insulator) or GOI (Germanium On Insulator) or the like.
And then fixing the substrate on a slide holder of a photoetching machine table, and coating a first photoresist layer on the substrate. In this embodiment, a spin coating method may be used to form a uniform photoresist coating on the substrate.
Next, step S2 is performed to etch the first photoresist layer and form a trench on the substrate. In this embodiment, the trench may be formed by etching using a wet chemical etching/dry etching method with the patterned photoresist layer as a mask. In this embodiment, the trench is located in an alignment region of the substrate.
Then, step S3 is performed to remove the first photoresist layer remaining on the substrate, and coat a second photoresist layer on the substrate, so that the second photoresist layer covers the trench. After the etching is completed, the first photoresist layer loses its effect and needs to be removed first. In this embodiment, the first photoresist layer may be stripped by wet cleaning or plasma cleaning, which is not limited in this application.
In this embodiment, the surface of the second photoresist layer is flat, that is, the second photoresist layer is higher than the trench after filling the trench.
And finally, step S4 is executed, the second photoresist layer is etched, an alignment mark is formed in the trench, the alignment mark includes four identical bar-shaped patterns, and the ratio of the sum of the depth of the trench and the thickness of the second photoresist layer around the trench to the width of the bar-shaped patterns is smaller than the design value.
Referring to fig. 2, fig. 2 is a schematic view of a photolithography alignment mark and a trench provided in the present embodiment. The alignment mark includes two first bar patterns 110 arranged along an X direction and two second bar patterns 120 arranged along a Y direction, the first bar patterns 110 are identical to the second bar patterns 120, and the two first bar patterns 110 and the two second bar patterns 120 are arranged symmetrically with respect to a center of the alignment mark.
In this example, the design value is 2. That is, for example, when the ratio of the sum of the depth of the trench and the thickness of the second photoresist layer at the periphery of the trench to the width d of the stripe pattern is less than 2, the problem of collapse of the alignment mark is less likely to occur. For example, for a conventional alignment mark, the sum of the depth of the trench and the thickness of the second photoresist layer at the periphery of the trench is 6 microns, and the width d of the bar pattern is 2 microns, when the aspect ratio of the bar pattern is 6 divided by 2 to equal 3. In the present embodiment, by increasing the width d of the bar pattern, for example, to 3 μm, the aspect ratio of the bar pattern is 6 divided by 3 and is equal to 2, and thus, it can be seen that by increasing the width d of the bar pattern, the aspect ratio can be reduced. Similarly, the aspect ratio may also be reduced by reducing the thickness of the second photoresist layer or the depth of the trench, which is not limited in this application.
In the present embodiment, the width d of the bar pattern may be understood as a length of the first bar pattern 110 in the Y direction and a length of the second bar pattern 120 in the X direction.
In addition, please refer to fig. 3 during the alignment, and fig. 3 is a schematic diagram of the front layer alignment mark and the current layer alignment mark provided in the present embodiment. Since the area of the front layer alignment mark 10 is larger than the area of the current layer alignment mark 20, the upper boundary or the lower boundary of the front layer alignment mark 10 is usually closer to the upper boundary or the lower boundary of the trench 30, so that the measurement accuracy is often affected by the thin films on the upper boundary and the lower boundary of the trench, which leads to abnormal measurement.
Therefore, the present embodiment further defines the outer boundaries of the first bar pattern 110 and the second pattern and the boundary of the trench 30.
Specifically, with continued reference to fig. 2, a first gap h1 is formed between the outer boundary of the first stripe pattern 110 and the boundary of the trench 30. The first gap h1 is not less than 5 microns.
A second gap h2 is provided between the outer boundary of the second bar pattern 120 and the boundary of the groove 30. The second gap h2 is not less than 30 microns. That is, the distance between the trench 30 and the boundaries of the first and second bar patterns 110 and 120 may be ensured by changing the length or width of the trench 30, thereby avoiding the influence on the measurement.
In this embodiment, the alignment mark is located at the very center of the trench 30. Of course, the alignment mark may be placed in other positions of the trench 30, which is not limited in this application.
In this embodiment, the first photoresist layer and the second photoresist layer may be a positive photoresist or a negative photoresist, which is not limited in this application.
Based on this, with reference to fig. 2, the present application further provides a lithographic alignment mark formed by the method for forming a lithographic alignment mark. The alignment mark includes two first bar patterns 110 arranged along an X direction and two second bar patterns 120 arranged along a Y direction, the first bar patterns 110 are identical to the second bar patterns 120, and the two first bar patterns 110 and the two second bar patterns 120 are arranged symmetrically with respect to a center of the alignment mark.
In summary, the present invention provides a photolithography alignment mark and a forming method thereof, wherein the forming method comprises the following steps: providing a substrate, and coating a first photoresist layer on the substrate; etching the first photoresist layer to form a groove on the substrate; removing the first photoresist layer remained on the substrate, and coating a second photoresist layer on the substrate to enable the second photoresist layer to cover the groove; and etching the second photoresist layer, forming an alignment mark in the groove, wherein the alignment mark comprises four same strip-shaped patterns, and the ratio of the sum of the depth of the groove and the thickness of the second photoresist layer at the periphery of the groove to the width of the strip-shaped patterns is smaller than a design value. And strictly controlling the depth-to-width ratio of the alignment mark by enabling the ratio of the sum of the depth of the groove and the thickness of the second photoresist layer at the periphery of the groove to the width of the strip pattern to be smaller than a design value, improving the environment where the alignment mark is located and avoiding the problem that the alignment mark collapses due to overlarge depth-to-width ratio.
It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. It will be apparent to those skilled in the art from this disclosure that many changes and modifications can be made, or equivalents modified, in the embodiments of the invention without departing from the scope of the invention. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention are still within the protection scope of the technical solution of the present invention, unless the content of the technical solution of the present invention is departed from.
Claims (10)
1. A method for forming a lithography alignment mark comprises the following steps:
providing a substrate, and coating a first photoresist layer on the substrate;
etching the first photoresist layer to form a groove on the substrate;
removing the first photoresist layer remained on the substrate, and coating a second photoresist layer on the substrate to enable the second photoresist layer to cover the groove;
and etching the second photoresist layer, and forming an alignment mark in the groove, wherein the alignment mark comprises four same strip-shaped patterns, so that the ratio of the sum of the depth of the groove and the thickness of the second photoresist layer at the periphery of the groove to the width of the strip-shaped patterns is smaller than a design value.
2. The method of forming a lithographic alignment mark according to claim 1, wherein said design value is 2.
3. The method of forming a lithographic alignment mark according to claim 1, wherein the alignment mark comprises two first bar patterns arranged along an X direction and two second bar patterns arranged along a Y direction, the first bar patterns and the second bar patterns are identical, and both the first bar patterns and the second bar patterns are symmetrically arranged about a center of the alignment mark.
4. The method of forming a lithographic alignment mark according to claim 3, wherein a first gap is provided between an outer boundary of the first bar pattern and a boundary of the trench.
5. The method of forming a lithographic alignment mark according to claim 4, wherein said first gap is not less than 5 μm.
6. The method of forming a lithographic alignment mark according to claim 3, wherein a second gap is provided between an outer boundary of the second stripe pattern and a boundary of the trench.
7. The method of forming a lithographic alignment mark of claim 6, wherein said second gap is not less than 30 microns.
8. The method of forming a lithographic alignment mark according to claim 1, wherein said alignment mark is located at the very center of said trench.
9. The method of claim 1, wherein the substrate is aluminum.
10. A lithographic alignment mark formed by the method of forming a lithographic alignment mark according to any one of claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202110617458.1A CN113394198A (en) | 2021-05-28 | 2021-05-28 | Photoetching alignment mark and forming method thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110617458.1A CN113394198A (en) | 2021-05-28 | 2021-05-28 | Photoetching alignment mark and forming method thereof |
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| CN113394198A true CN113394198A (en) | 2021-09-14 |
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| CN202110617458.1A Pending CN113394198A (en) | 2021-05-28 | 2021-05-28 | Photoetching alignment mark and forming method thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114236983A (en) * | 2021-12-30 | 2022-03-25 | 北海惠科半导体科技有限公司 | Method for manufacturing alignment mark of photoetching machine and wafer |
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| KR950012591A (en) * | 1993-10-15 | 1995-05-16 | 김주용 | Manufacturing Method of Semiconductor Device |
| KR20030059377A (en) * | 2001-12-29 | 2003-07-10 | 동부전자 주식회사 | Method for forming overlay measurement pattern capable of using with a alignment mark |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114236983A (en) * | 2021-12-30 | 2022-03-25 | 北海惠科半导体科技有限公司 | Method for manufacturing alignment mark of photoetching machine and wafer |
| CN114236983B (en) * | 2021-12-30 | 2024-03-22 | 北海惠科半导体科技有限公司 | Manufacturing method of alignment mark of photoetching machine and wafer |
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