CN115440707A - Alignment mark structure and forming method thereof - Google Patents

Alignment mark structure and forming method thereof Download PDF

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Publication number
CN115440707A
CN115440707A CN202211147128.1A CN202211147128A CN115440707A CN 115440707 A CN115440707 A CN 115440707A CN 202211147128 A CN202211147128 A CN 202211147128A CN 115440707 A CN115440707 A CN 115440707A
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Prior art keywords
alignment
layer
etching
mark
chamfer
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罗先刚
张译尹
罗云飞
刘凯鹏
朱瑶瑶
赵泽宇
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Institute of Optics and Electronics of CAS
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Institute of Optics and Electronics of CAS
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Priority to CN202211147128.1A priority Critical patent/CN115440707A/en
Priority to PCT/CN2022/129510 priority patent/WO2024060361A1/en
Publication of CN115440707A publication Critical patent/CN115440707A/en
Pending legal-status Critical Current

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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
    • 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
    • G03F9/7076—Mark details, e.g. phase grating mark, temporary mark
    • 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

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)

Abstract

The present disclosure provides an alignment mark structure and a method of forming the same, the alignment mark structure including: a substrate (1); a marking region (2) comprising an alignment structure (2-2) and a chamfer structure layer (2-1); the alignment structure (2-2) is formed in the substrate (1) and is a concave structure; the chamfer structure layer (2-1) is formed on the surface of the substrate (1) and is of a convex structure, and the chamfer structure layer (2-1) forms a convex chamfer structure at the edge of the alignment structure (2-2); and the non-marking region (6) is arranged around the periphery of the marking region (2), and the upper surface of the non-marking region (6) is lower than the lower surface of the chamfer structure layer (2-1) in the marking region (2). The alignment mark structure can effectively improve the definition and contrast of alignment mark detection.

Description

Alignment mark structure and forming method thereof
Technical Field
The present disclosure relates to the field of lithography alignment technology, and more particularly, to an alignment mark structure and a method for forming the same.
Background
In actual IC manufacturing, several tens of processes are often performed from wafer to final test package, and the whole manufacturing process is completed in a stacking manner. Therefore, the alignment marks must be used to achieve alignment values of the current layer and the previous layer within an allowable error range. However, the alignment mark is affected by the previous process to reduce the photolithography alignment accuracy, because before a certain layer of photolithography, the surface of the alignment mark may be covered with a thin film such as silicon oxide, silicon nitride, a metal layer, a photoresist layer, etc., which affects the definition and contrast of the alignment mark. Particularly, as the IC process technology is gradually reduced, more film layers cover the surface of the wafer and are used for realizing the etching transfer of the pattern. These layers will interfere with the alignment signals to some extent, causing distortion of the alignment marks and affecting the detection of the alignment marks in the previous photolithography process.
Fig. 1 is a schematic cross-sectional view of a conventional alignment mark before a photolithography process, which includes an alignment mark on a substrate structure and a multi-layer film covering the surface of the alignment mark. The multilayer film has filled the bottom of the alignment mark and the surface of the multilayer film forms an obtuse angle at the edge of the alignment mark. Because the thickness of the multilayer film at the edge of the alignment mark is not uniform, the alignment light incident on the edge of the alignment mark cannot be vertically reflected along one direction, thereby causing unclear alignment signals. Since the bottom of the alignment mark is also substantially filled with the multilayer film, the contrast of the bottom of the alignment mark with respect to the substrate surface is greatly reduced.
Therefore, the low contrast of the alignment mark may make it difficult for the CCD camera to detect the alignment mark signal, and the unclear edge of the alignment mark may distort the alignment signal detected by the CCD camera, thereby causing a decrease in alignment accuracy and affecting the lithography quality.
Disclosure of Invention
Technical problem to be solved
In view of the above problems, the present disclosure provides an alignment mark structure and a method for forming the same, which are used to solve the technical problems of unclear alignment signal edge, low contrast, and the like in the conventional alignment mark structure during detection.
(II) technical scheme
One aspect of the present disclosure provides an alignment mark structure, including: a substrate; a mark region including an alignment structure and a chamfer structure layer; the alignment structure is formed in the substrate through etching and is a concave structure; the chamfer structure layer is formed on the surface of the substrate through deposition and is of a convex structure, and the chamfer structure layer forms a convex chamfer structure at the edge of the alignment structure; and the non-marking area is arranged around the periphery of the marking area, and the upper surface of the non-marking area is lower than the lower surface of the chamfer structure layer in the marking area.
Further, the bottom and the side wall of the alignment structure are provided with high-reflectivity thin film layers; the thickness of the high-reflectivity film layer is not more than 100nm, and the material of the high-reflectivity film layer comprises one of Au, al and Ag.
Furthermore, the planar size range of the alignment structure is 0.5-50 μm, and the recess depth of the alignment structure is 100-4000 nm.
Further, the alignment structure includes one of a cross-shaped alignment mark and a grid-type alignment mark.
Furthermore, the thickness of the chamfer angle structure layer is not more than 100nm, and the inclination angle of the chamfer angle structure is 35-55 degrees; the chamfer structure layer is made of a non-transparent medium which is easy to etch and control and comprises one of silicon nitride, aluminum nitride, silicon carbide and polycrystalline silicon.
Furthermore, the non-mark area is of a zigzag structure and is arranged in the range of 1-1000 mu m around the periphery of the alignment structure; the non-mark area is formed in the substrate by etching, and the etching depth of the non-mark area is not more than 1/2 of the depth of the concave structure.
Another aspect of the present disclosure provides a method for manufacturing an alignment mark structure, including: s1, forming a chamfer layer on a substrate; s2, coating a first photosensitive layer; etching the mark area after exposure and development, wherein the chamfering layer and the substrate are sequentially etched to obtain an alignment structure; s3, etching the chamfer layer at the edge of the alignment structure to obtain a raised chamfer structure, and removing the first photosensitive layer; s4, coating a second photosensitive layer; etching the periphery of the marking area after exposure and development, wherein the chamfering layer and the substrate are sequentially etched to obtain a non-marking area and a chamfering structure layer; and S5, removing the second photosensitive layer to obtain a target alignment mark structure.
Further, after S3, the method further includes: s31, depositing a high-reflectivity film layer, wherein the deposited thickness is not more than 100nm.
Further, S5 further includes: and removing the high-reflectivity thin film layer on the chamfer structure layer.
Further, the etching method in S3 is dry etching, the dry etching includes one of reactive ion etching and inductively coupled plasma etching, and the etching gas includes SF 6 、O 2 、N 2 、CHF 3 、Cl 2 Ar and C 4 F 8 One of (1); the inclination angle of the convex chamfer structure obtained by etching is 35-55 degrees.
(III) advantageous effects
According to the alignment mark structure and the forming method thereof, the chamfer structure layer with higher height is arranged on the mark area, and the non-mark area with lower height is arranged on the periphery of the mark area, so that the surface of the mark area is closer to the mask, the surface of the non-mark area is farther away from the mask, the contrast of the mark area relative to the non-mark area is higher during detection, and a detection signal of an alignment mark is easier to obtain; furthermore, a raised chamfer structure is formed in the chamfer structure layer, so that deposited multilayer films can be effectively prevented from being accumulated at the edge of the alignment structure, incident light rays at the edge of the alignment structure can be reflected along one direction, and the edge definition of the alignment structure is obviously improved.
Drawings
FIG. 1 is a schematic diagram showing a cross-sectional structure and light reflection of a conventional alignment mark before a photolithography process;
FIG. 2 schematically illustrates a cross-sectional structure and a light reflection diagram of an alignment mark before a photolithography process according to an embodiment of the present disclosure;
FIG. 3 schematically illustrates a top view of a positional relationship of a mark region and a non-mark region and a contrast relationship therebetween in accordance with an embodiment of the present disclosure;
FIG. 4 schematically illustrates a flow chart of a method of fabricating an alignment mark structure according to an embodiment of the present disclosure;
FIG. 5 is a schematic diagram illustrating the process flow steps of an alignment mark structure according to an embodiment of the present disclosure;
fig. 6 schematically illustrates an image of an alignment mark with a chamfered structure and a marked region under a CCD camera according to embodiment 1 of the present disclosure;
FIG. 7 schematically shows an image of an alignment mark without a chamfered structure and a mark-free region under a CCD camera according to comparative example 1 of the present disclosure;
FIG. 8 schematically shows an image of an alignment mark without a mark region under a CCD camera according to comparative example 2 of the present disclosure;
FIG. 9 schematically shows an image of an alignment mark without a chamfered structure under a CCD camera according to comparative example 3 of the present disclosure;
description of reference numerals:
1, a substrate; 2, a marking region; 3, multilayer film; 4, incident light; 5, reflecting light; 5-1, illuminating light reflected at the surface of the multilayer film; 5-2, illuminating light reflected directly on the substrate; 5-3, illuminating the sum of irregularly scattered light reflections at the edges of the marking area; 5-4, illuminating the light rays which are reflected back to the air after being reflected for multiple times in the multilayer film; 2-1, chamfering the structural layer; 2-2, aligning the structure; 6-a non-label region; 7, chamfering layers; 8-1, a first photosensitive layer; 8-2, a second photosensitive layer; 9-1, a first mask; 9-2, a second mask; 10, an exposure light source; 11, high-reflectivity film layer.
Detailed Description
For the purpose of promoting a better understanding of the objects, aspects and advantages of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The terms "comprises," "comprising," and the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.
It should be noted that, if directional indication is referred to in the embodiments of the present disclosure, the directional indication is only used to explain a relative positional relationship, a motion situation, and the like between components in a certain posture, and if the certain posture is changed, the directional indication is changed accordingly.
An embodiment of the present disclosure provides an alignment mark structure, please refer to fig. 2, including: a substrate 1; the marking region 2 comprises an alignment structure 2-2 and a chamfer structure layer 2-1; the alignment structure 2-2 is formed in the substrate 1 and is a concave structure; the chamfer structure layer 2-1 is formed on the surface of the substrate 1 and is of a convex structure, and the chamfer structure layer 2-1 forms a convex chamfer structure at the edge of the alignment structure 2-2; and a non-mark region 6 disposed around the periphery of the mark region 2, wherein an upper surface of the non-mark region 6 is lower than a lower surface of the chamfer structure layer 2-1 in the mark region 2.
The alignment mark structure of the present disclosure includes a mark region 2 formed on a substrate 1 and a non-mark region 6 disposed around the mark region 2. The marking region 2 comprises a preset alignment structure 2-2 and a chamfer structure layer 2-1 which is higher than the initial surface of the substrate 1; the non-mark region 6 is formed in the substrate 1 below the lower surface of the bevel structure layer 2-1 (i.e., the initial surface of the substrate 1), so that the height of the mark region 2 is higher and the height of the non-mark region 6 is lower, thereby enabling the surface of the mark region 2 to be closer to the mask in proximity contact lithography (e.g., super resolution lithography) and the non-mark region 6 to have a larger gap with respect to the mask. I.e. the distance of the non-marked area 6 relative to the mask is larger than the distance of the marked area 2 relative to the mask at the time of alignment mark detection, this arrangement allows the non-marked area 6 to be darker, the marked area 2 to be brighter and the contrast between the marked area 2 and the non-marked area 6 to be greater under the whole CCD camera, thus making the alignment arrangement 2-2 easier to find under the CCD camera, especially for proximity contact lithography, which is necessary for structural optimization. Therefore, the problem that the contrast of the alignment structure 2-2 in the mark area 2 is reduced due to too bright reflected light of the non-mark area 6 is solved.
Further, the deposited multilayer film 3 can be effectively prevented from being accumulated at the edge of the alignment structure 2-2 by forming the convex chamfering structure in the chamfering structure layer 2-1, as shown in fig. 2, the multilayer film 3 forms a smooth and uniform transition on the chamfering structure, so that incident light illuminating at the edge of the alignment structure 2-2 can be reflected along one direction, and the incident light comprises light 5-1 reflected by the surface of the multilayer film, light 5-2 directly reflected by the illumination on the substrate, and the sum of irregular scattered light reflection 5-3 illuminated at the edge of the mark area, thereby remarkably improving the edge definition of the alignment structure 2-2.
On the basis of the above embodiment, the bottom and the side wall of the alignment structure 2-2 are provided with the high-reflectivity film layer 11; the thickness of the high-reflectivity thin film layer 11 is not more than 100nm, and the material of the high-reflectivity thin film layer comprises one of Au, al and Ag.
The alignment mark structure can further arrange a high-reflectivity thin film layer 11 on the bottom and the side wall of the alignment structure 2-2, the high-reflectivity thin film layer 11 is made of high-reflectivity materials, and comprises metal thin films such as Au, al and Ag, and the metal thin films can enhance the intensity of reflected light of the alignment structure 2-2, so that the contrast of the alignment structure 2-2 is further improved.
On the basis of the above embodiment, the planar size of the alignment structure 2-2 ranges from 0.5 to 50 μm, and the recess depth of the alignment structure 2-2 ranges from 100 to 4000nm.
The alignment structure 2-2 forms an alignment mark pattern on a plane, and its plane size range is generally set within the above range in order to find the position of the alignment mark pattern. The etching depth of the alignment structure 2-2 should not be too small, otherwise the definition of the alignment structure 2-2 is affected and it is difficult to identify accurately.
On the basis of the above embodiment, the alignment structure 2-2 includes one of a cross-shaped alignment mark and a grid-type alignment mark.
The cross-shaped alignment mark is usually used for a coarse alignment scene, and has the advantage of quickly finding the relative position relationship between the mask and the wafer; grid-type alignment marks are typically used for fine alignment of the scene, with the advantage of fine adjustment of the relative position of each exposure field to the reticle.
On the basis of the embodiment, the thickness of the chamfer structure layer 2-1 is not more than 100nm, and the inclination angle of the chamfer structure is 35-55 degrees; the material of the chamfer structure layer 2-1 is a medium which is easy to etch and control and is non-transparent, and comprises one of silicon nitride, aluminum nitride, silicon carbide and polysilicon.
Although the chamfer structure layer 2-1 is used to bring the surface of the mark region 2 closer to the mask, it is not preferred that its thickness exceed 100nm, which would otherwise affect the duty cycle observed by the alignment structure 2-2 under the CCD. The inclination angle of the chamfer structure is in the range, and the technical effect of enabling the multilayer film 3 to be uniformly covered is achieved. The chamfer structure layer 2-1 is made of non-transparent medium to improve the reflectivity of the surface of the mark area 2.
On the basis of the above embodiment, the non-mark region 6 is a zigzag structure and is arranged in the range of 1-1000 μm around the periphery of the alignment structure 2-2; the non-mark region 6 is formed in the substrate 1 by etching to a depth not more than 1/2 of the depth of the recess structure.
The zigzag structure is a full-surrounding structure, and the non-mark region 6 surrounds the entire mark region 2, as shown in fig. 3, the mark region 2 and the non-mark region 6 form a complete alignment mark structure. The etching depth of the non-mark region 6 is not more than 1/2 of the depth of the recessed structure, and too deep etching depth also affects the contrast of the bottom of the alignment structure 2-2 with respect to the bottom of the non-mark region 6.
An embodiment of the present disclosure further provides a method for manufacturing an alignment mark structure, as shown in fig. 4 to 5, including: s1, forming a chamfer layer 7 on a substrate 1; s2, coating a first photosensitive layer 8-1; etching the mark region 2 after exposure and development, wherein the chamfering layer 7 and the substrate 1 are etched in sequence to obtain an alignment structure 2-2; s3, etching the chamfer layer 7 at the edge of the alignment structure 2-2 to obtain a convex chamfer structure, and removing the first photosensitive layer 8-1; s4, coating a second photosensitive layer 8-2; etching the periphery of the marking region 2 after exposure and development, wherein the chamfering layer 7 and the substrate 1 are sequentially etched to obtain a non-marking region 6 and a chamfering structure layer 2-1; and S5, removing the second photosensitive layer 8-2 to obtain a target alignment mark structure.
The preparation method of the alignment mark structure comprises the following steps: after the chamfer layer 7 is prepared, firstly etching to obtain an alignment structure 2-2, then etching to obtain a convex chamfer structure, and finally etching to obtain a non-marking area 6 and a chamfer structure layer 2-1, so that a target alignment mark structure can be obtained. The etching steps are conventional photoetching processes, and the preparation method is simple and easy to operate.
On the basis of the above embodiment, S3 is followed by: s31, depositing the high-reflectivity thin film layer 11, wherein the deposited thickness is not more than 100nm.
After the step of etching to obtain the raised chamfer structure and before the step of etching to obtain the non-mark area 6, a high-reflectivity film layer 11 can be sputtered and deposited in the alignment structure 2-2, so that the contrast of the alignment structure 2-2 is further improved.
On the basis of the above embodiment, S5 further includes: and removing the high-reflectivity thin film layer 11 on the chamfer structure layer 2-1.
After the high-reflectivity thin film layer 11 is deposited and the second photosensitive layer 8-2 is removed in the step S31, the residual high-reflectivity thin films on the upper surface of the chamfer structure layer 2-1 and the upper surface of the non-mark area 6 can be simultaneously removed, and the high-reflectivity thin films are only formed on the bottom and the side wall of the alignment structure 2-2.
On the basis of the above embodiment, the etching method in S3 is dry etching, the dry etching includes one of reactive ion etching and inductively coupled plasma etching, and the etching gas includes SF 6 、O 2 、N 2 、CHF 3 、Cl 2 Ar and C 4 F 8 One of (1); the inclination angle of the convex chamfer structure obtained by etching is 35-55 degrees.
The chamfer structure is selected to be dry etched, so that the 2-2 steepness of the alignment structure can be protected, and the inclination angle of the chamfer structure can be regulated and controlled in the modes of etching gas flow, etching time, power, cavity pressure and the like.
According to the alignment mark structure and the forming method thereof, on one hand, the chamfer structure layer with higher height is arranged on the mark area, and the non-mark area with lower height is arranged on the periphery of the mark area, so that the surface of the mark area is closer to the mask, and the surface of the non-mark area is farther away from the mask, and the contrast of the alignment structure is improved; the high-reflectivity film layers are arranged at the bottom and the side wall of the alignment structure, so that the reflected light intensity of the alignment structure is enhanced, and the contrast of the alignment structure is further improved; on the other hand, the raised chamfer structure is formed in the chamfer structure layer, so that the multilayer film can be favorably and uniformly covered on the chamfer structure of the mark area, incident light rays at the edge of the alignment structure can be reflected along one direction, and the edge definition of the alignment structure is obviously improved. In combination with the above two aspects, the present disclosure reduces distortion of the alignment structure, thereby reducing alignment errors in IC fabrication.
The present disclosure is further illustrated by the following detailed description. The alignment mark structure and the forming method thereof are specifically described in the following embodiments. However, the following examples are merely illustrative of the present disclosure, and the scope of the present disclosure is not limited thereto.
The alignment mark structure of the embodiment comprises a mark region 2 formed on a substrate 1 and a non-mark region 6 arranged around the mark region, wherein the mark region 2 comprises a preset alignment structure 2-2 and a chamfer angle structure layer 2-1, the plane size range of the alignment structure 2-2 is 0.5-50 μm, the alignment structure is a concave structure, and the etching depth of the alignment structure is 100-4000 nm; the chamfer structure layer 2-1 is a convex structure, the thickness of the chamfer structure layer 2-1 is not more than 100nm, and the inclination angle of the chamfer structure is 35-55 degrees. The non-mark region 6 may be a zigzag region within a range of 1 to 1000 μm from the edge of the mark region 2. The etching depth of the non-mark region 6 is not more than 1/2 of the etching depth of the alignment structure 2-2, and the etching depth of the non-mark region 6 is 100-2000 nm.
The method for manufacturing the alignment mark structure of the present embodiment includes the following steps, as shown in fig. 5:
step (1): preparing a substrate 1;
step (2): preparing a chamfer layer 7 on the surface of the substrate 1, wherein the thickness d1 of the chamfer layer 7 is 10-100 nm; corresponding to the step S1;
and (3): preparing a first photosensitive layer 8-1 on the chamfer layer 7, the thickness d of the first photosensitive layer 8-1 2 100-1000 nm;
and (4): performing exposure development on the basis of the step (3), wherein a first mask plate 9-1 is an alignment mark mask plate, and an exposure light source 10 is arranged above the first mask plate 9-1;
and (5): etching the pattern obtained by the development in the step (4), firstly, taking the first photosensitive layer 8-1 as a mask to etch the chamfer layer 7, and etching to penetrate through the chamfer layer 7;
and (6): on the basis of the step (5), the first photosensitive layer 8-1 and the chamfer layer 7 are used as masking etching linersBottom 1, obtaining an alignment structure 2-2, and etching depth d of the alignment structure 2-2 5 100-4000 nm; corresponding to the step S2;
and (7): etching a chamfer structure, wherein the inclination angle of the chamfer structure is 35-55 degrees; corresponding to the step S3;
and (8): removing the etching residual photoresist on the surface of the chamfer layer 7;
and (9): selectively preparing a high-reflectivity thin film layer 11, wherein the thickness d6 of the high-reflectivity thin film layer 11 is 10-100 nm;
step (10): preparing a second photosensitive layer 8-2 on the chamfer layer 7, the thickness d of the second photosensitive layer 8-2 7 100-1000 nm;
step (11): exposing and developing again on the basis of the step (10) to form a non-mark region 6;
step (12): etching is carried out on the basis of the step (11), the chamfer layer 7 and the substrate 1 are sequentially etched, the high-reflectivity thin film layer 11 can be selectively etched, and the depth d of the substrate 1 can be selectively etched 8 Forming a chamfer structure layer 2-1 and a non-marking area 6 at 10-2000 nm; corresponding to the step S4;
step (13): removing the residual photoresist on the surface of the substrate 1, and optionally simultaneously removing the residual high-reflectivity film layers on the upper surfaces of the chamfer structure layer 2-1 and the non-marking area 6; corresponds to the step S5.
In the step (1), the substrate 1 may be a silicon-based substrate, a sapphire substrate, a silicon carbide substrate, or the like.
The material of the chamfer layer 7 in the step (2) should be selected from a dielectric which is easy to etch and control and is non-transparent, and may be one of silicon nitride, aluminum nitride, silicon carbide and polysilicon.
The first photosensitive layer 8-1 in the step (3) and the second photosensitive layer 8-2 in the step (10) are prepared by the same spin coating method.
The alignment mark on the alignment mark mask in the step (4) may include a cross-shaped alignment mark, a grid-shaped alignment mark, and the like.
The exposure process of the above steps (4) and (11) may be proximity contact exposure, laser direct writing processing, projection lithography, or the like.
The etching of the chamfer layer 7 in the step (5) is dry etching, including ion beam etching, reactive ion beam etching or inductively coupled plasma etching, and the optional gas is SF 6 、O 2 、N 2 、CHF 3 、Cl 2 Ar and C 4 F 8 And the like.
The etching of the substrate 1 in the step (6) is dry etching or wet etching, which may include ion beam etching, reactive ion beam etching or inductively coupled plasma etching, and the optional gas is SF 6 、CHF 3 Or Ar; the wet etching solution may be mixed solution of KOH and IPA, and concentrated H 2 SO 4 And H 3 PO 4 Mixed solution of the proportions, and the like.
The inclination angle of the chamfer structure in the step (7) is 35-55 degrees. The etching method of the chamfer structure is dry etching, including reactive ion etching and inductively coupled plasma etching, and the selectable gas is SF 6 、O 2 、N 2 、CHF 3 、Cl 2 Ar and C 4 F 8 And so on.
The photoresist on the surface etching residue in the steps (8) and (13) can be removed by a dry method or a wet method. The dry removal can be performed by reactive ion beam etching or inductively coupled plasma etching, and the etching gas can be O 2 (ii) a The solution for wet removal may be ethanol, acetone, concentrated sulfuric acid, etc.
The high reflection film is deposited on the bottom and the side wall of the alignment structure 2-2 in the step (9).
The etching of the non-mark region 6 in the step (11) may be dry etching or wet etching. The dry etching may be ion beam etching, reactive ion beam etching or inductively coupled plasma etching, and the optional gas is SF 6 、CHF 3 Or Ar; the wet etching solution may be a mixed solution of KOH and IPA, H 2 SO 4 And H 3 PO 4 The mixed solution of (2), and the like.
In accordance with the above protocol, 4 specific examples and 3 comparative examples are provided below.
The first embodiment is as follows:
as shown in fig. 2, the alignment mark structure of the present embodiment is formed as follows:
the substrate 1 is a silicon-based material; the material of the chamfer layer 7 is Si 3 N 4 The thickness is 20nm, and the preparation method is magnetron sputtering coating;
preparing a first photosensitive layer 8-1 by adopting a spin coating mode, wherein the material model of the first photosensitive layer 8-1 is AR-P3170, and the thickness is 100nm;
the light blocking layer on the first mask 9-1 is made of metal Cr, the thickness of the metal Cr is 100nm, and the substrate is quartz; the mark pattern on the first mask 9-1 is a grating structure with a period of 20 μm, the length of the grating is 40 μm, and the area of the mark pattern is 200 μm by 40 μm; the first mask 9-1 is also provided with a coarse alignment mark, the mark is in a cross shape, and the width is 10 mu m; exposing a mark pattern on the first mask 9-1 to the first photosensitive layer 8-1 by adopting contact photoetching;
si of post-development etched chamfer layer 7 3 N 4 Etching with SF as etching gas by reactive ion beam 6 And O 2 The gas flow ratio is 5: 1, the cavity pressure is 1Pa, the power is 40w, the etching time is 20s, and the etching depth is 20nm; etching the alignment structure 2-2 by using reactive ion beam etching (RIE) with etching gas SF 6 、CHF 3 The cavity pressure is 1Pa, the power is 100w, the etching time is 10min, and the etching depth is 1500nm; etching Si of chamfer layer structure 2-1 3 N 4 Etching with reactive ion beam (SF) as etching gas 6 、O 2 And N 2 Wherein SF 6 And O 2 The gas flow ratio of the chamber is 3: 1, the chamber pressure is 1Pa, the power is 40w, the etching time is 10s, and the inclination angle of the chamfer is about 35 degrees;
removing the residual first photosensitive layer 8-1, soaking the substrate in acetone until the first photosensitive layer 8-1 falls off, washing with deionized water, and drying the substrate 1;
preparing a second photosensitive layer 8-2, and spin-coating a photoresist AR-1500 with the thickness of 500nm; the non-marking area 6 on the second mask 9-2 is in a shape of Chinese character 'hui', the area of the inner circle is 201μm 41μm, and the area of the outer circle is 400μm 240 μm; the second mask 9-2 also comprises a cross-shaped alignment mark matched with the first mask 9-1; the light blocking material on the second mask 9-2 is metal Cr with the thickness of 100nm, and the substrate is quartz;
exposing the non-mark area 6 on the second mask 9-2 to the second photosensitive layer 8-2 by adopting a contact exposure process; etching the unmarked area 6 by adopting an ion beam after development, wherein the etching time is 5min, the rotation angle of the substrate is 15 degrees, the chamfer layer 7 and the etched part of the substrate 1 are etched through at one time to form a chamfer structure layer 2-1 and the unmarked area 6, and the etching depth of the unmarked area 6 (part of the substrate 1) is 500nm; and removing the residual second photosensitive layer 8-2, soaking the substrate 1 by using acetone until the second photosensitive layer 8-2 falls off, washing by using deionized water, and drying the substrate 1.
The chamfered structure 2-1 overlying the alignment structure 2-2 in this embodiment has a tilt angle of about 35 deg., si 3 N 4 The thickness of the chamfer structure layer is 20nm, and the multilayer film 3 covers the chamfer structure and has a gentle transition, so that the reflected light rays are emitted from the same angle, and the definition of the alignment structure can be improved.
The distance between the non-mark area 6 and the upper surface of the chamfer structure layer 2-1 is increased to 520nm, and the structure increases the gap between the non-mark area 6 and the mask as shown in FIG. 3 to a certain extent, so that the reflectivity of the non-mark area 6 is reduced, and the contrast of the mark area 2 relative to the non-mark area 6 is increased. Fig. 6 shows the alignment mark structure obtained by the method of this embodiment, which has a clear image under the CCD camera, and thus the method of the present disclosure is proved to be effective.
Example two:
as shown in fig. 2, the alignment mark structure of the present embodiment is formed as follows:
the substrate 1 is a silicon-based material; the material of the chamfer layer 7 is AlN, the thickness is 100nm, and the preparation method is atomic layer deposition;
preparing a first photosensitive layer 8-1 by adopting a spin coating mode, wherein the material model of the first photosensitive layer 8-1 is AR-P3170, and the thickness is 100nm; the light blocking layer on the first mask 9-1 is made of metal Cr, the thickness of the metal Cr is 100nm, and the substrate is quartz; the mark pattern on the first mask 9-1 is a square chessboard grid with the period of 10 μm, and the area of the mark pattern is 400 μm by 200 μm; the first mask 9-1 is also provided with a coarse alignment mark, the mark is cross-shaped and has a width of 10 mu m; exposing a mark pattern on the first mask 9-1 to the first photosensitive layer 8-1 by adopting contact photoetching;
AlN of the chamfer layer 7 is etched after development, and the etching gas for reactive ion beam etching is Cl 2 And Ar, the gas flow ratio is 5: 1, the cavity pressure is 0.5Pa, the power is 20w, the etching time is 100s, and the etching depth is 100nm; etching the alignment structure 2-2 by using reactive ion beam etching (RIE) with etching gas SF 6 、CHF 3 The cavity pressure is 1Pa, the power is 100w, the etching time is 25min, and the etching depth is 4000nm; etching AlN of the chamfer layer structure 2-1 by reactive ion beam etching with Cl as etching gas 2 And Ar, wherein the gas flow ratio is 3: 1, the cavity pressure is 1Pa, the power is 40w, the etching time is 10s, and the inclination angle of the chamfer is about 40 degrees;
removing the residual first photosensitive layer 8-1, soaking the substrate in acetone until the first photosensitive layer 8-1 falls off, washing with deionized water and drying the substrate 1;
preparing a second photosensitive layer 8-2, and spin-coating a photoresist AR-3100 with the thickness of 1000nm; the pattern of the non-mark area 6 on the second mask 9-2 is in a shape of a Chinese character 'hui', the area of the inner circle is 401μm x 201 μm, and the area of the outer circle is 600 μm x 400 μm; the second mask 9-2 also comprises a cross-shaped alignment mark matched with the first mask 9-1; the light blocking material on the second mask 9-2 is metal Cr with the thickness of 100nm, and the substrate is quartz; exposing the non-mark area 6 on the second mask 9-2 to the second photosensitive layer 8-2 by adopting a contact exposure process; after development, ion beam etching is adopted, the chamfer layer 7 and part of the substrate 1 are etched and penetrated by one-time etching, the etching time is 10min, the rotation angle of the substrate is 15 degrees, a chamfer structure layer 2-1 and a non-marking area 6 are formed, and the etching depth of the non-marking area 6 (part of the substrate 1) is 1000nm; and removing the residual second photosensitive layer 8-2, soaking the substrate 1 in acetone until the second photosensitive layer 8-2 falls off, washing with deionized water, and drying the substrate 1.
In the embodiment, the chamfer structure layer 2-1 covered above the alignment structure 2-2 has an inclination angle of about 40 degrees, and the AlN chamfer structure layer has a thickness of 100nm, so that the multilayer film 3 has a smooth transition when covering above the chamfer structure, thereby emitting the reflected light from the same angle and further improving the definition of the alignment structure. The distance between the non-mark area 6 and the upper surface of the chamfer structure layer 2-1 is increased to 1100nm, and the concave structure increases the gap between the non-mark area 6 and the mask plate to a certain extent, so that the reflectivity of the non-mark area 6 is reduced, and the contrast of the mark area 2 relative to the non-mark area 6 is increased.
Example three:
as shown in fig. 2, the alignment mark structure of the present embodiment is formed as follows:
the substrate 1 is a sapphire material; the chamfer layer 7 is made of SiC with the thickness of 100nm and is prepared by plasma enhanced atomic layer deposition;
preparing a first photosensitive layer 8-1 by adopting a spin coating mode, wherein the material model of the first photosensitive layer 8-1 is AR-P3170, and the thickness is 500nm; the light blocking layer on the first mask 9-1 is made of metal Cr, the thickness of the metal Cr is 100nm, and the substrate is quartz; the mark pattern on the first mask 9-1 is a grating structure with the period of 20 μm, the length of the grating is 40 μm, and the area of the mark pattern is 200 μm by 40 μm; a mark for coarse alignment is also arranged on the first mask plate 9-1, the shape of the mark is cross, and the width of the mark is 10 mu m; exposing a mark pattern on the first mask 9-1 to the first photosensitive layer 8-1 by adopting contact photoetching;
etching SiC of the chamfer layer 7 after development by adopting an inductively coupled plasma etching process with etching gas of SF 6 、C 4 F 8 The total gas flow is 80sccm, the power of an upper electrode is 500w, the power of a lower electrode is 200w, the etching time is 2min, and the etching depth is 100nm; etching the alignment structure 2-2 by wet etching with an etching solution volume ratio of V (98% H) 2 SO 4 )∶V(85％H 3 PO 4 ) Etching time is 30min and etching depth is 4000nm, wherein the etching ratio is 3: 1; etching SiC of the chamfer layer structure 2-1 by adopting an inductively coupled plasma etching process with SF as etching gas 6 And C 4 F 8 The total gas flow is 80sccm, the upper electrode power is 1000w, the lower electrode power is 600w, the etching time is 30s, and the chamfer angle is made to be about 45 °；
Removing the residual first photosensitive layer 8-1, soaking the substrate in acetone until the first photosensitive layer 8-1 falls off, washing with deionized water, and drying the substrate;
preparing a second photosensitive layer 8-2, and spin-coating a photoresist AR-3100 with the thickness of 1000nm; the pattern of the non-mark area 6 on the second mask 9-2 is in a shape of a Chinese character 'hui', the area of the inner circle is 201μm 41μm, and the area of the outer circle is 400μm 240μm; the second mask 9-2 also comprises a cross-shaped alignment mark matched with the first mask 9-1; the light blocking material on the second mask 9-2 is metal Cr with the thickness of 100nm, and the substrate is quartz; exposing the non-mark area 6 on the second mask 9-2 to the second photosensitive layer 8-2 by adopting a contact exposure process; after development, ion beam etching is adopted, the chamfer layer 7 and part of the substrate 1 are etched and penetrated by one-time etching, the etching time is 10min, the rotation angle of the substrate is 15 degrees, a chamfer structure layer 2-1 and a non-marking area 6 are formed, and the etching depth of the non-marking area 6 (part of the substrate 1) is 1000nm; and removing the residual second photosensitive layer 8-2, soaking the substrate 1 in acetone until the second photosensitive layer 8-2 falls off, washing with deionized water, and drying the substrate 1.
In the embodiment, the chamfer angle structure layer 2-1 covered above the alignment structure 2-2 has an inclination angle of about 45 degrees, and the thickness of the SiC chamfer angle structure layer is 100nm, so that the multilayer film 3 has a gentle transition when covering the chamfer angle structure, reflected light rays are emitted from the same angle, and the definition of the alignment structure is further improved. The distance between the non-mark area 6 and the upper surface of the chamfer structure layer 2-1 is increased to 1100nm, and the concave structure increases the gap between the non-mark area 6 and the mask plate to a certain extent, so that the reflectivity of the non-mark area 6 is reduced, and the contrast of the mark area 2 relative to the non-mark area 6 is increased.
Example four:
as shown in fig. 2, the alignment mark structure of the present embodiment is formed as follows:
the substrate 1 is a silicon-based material; the material of the chamfer layer 7 is Si 3 N 4 The thickness is 20nm, and the preparation method is magnetron sputtering coating;
preparing a first photosensitive layer 8-1 by adopting a spin coating mode, wherein the material model of the first photosensitive layer 8-1 is AR-P3170, and the thickness is 100nm; the light blocking layer on the first mask 9-1 is made of metal Cr, the thickness of the metal Cr is 100nm, and the substrate is quartz; the mark pattern on the first mask 9-1 is a grating with the period of 20 μm, the length of the grating is 40 μm, and the area of the mark pattern is 200 μm by 40 μm; a mark for coarse alignment is also arranged on the first mask 9-1, the shape of the mark is a cross-shaped alignment mark, and the width of the mark is 10 mu m; exposing a mark pattern on the first mask 9-1 to the first photosensitive layer 8-1 by adopting contact photoetching;
si of post-development etched chamfer layer 7 3 N 4 Etching with reactive ion beam (SF) as etching gas 6 And O 2 The gas flow ratio is 5: 1, the cavity pressure is 1Pa, the power is 40w, the etching time is 20s, and the etching depth is 20nm; etching the alignment structure 2-2 by reactive ion beam etching with SF as etching gas 6 And CHF 3 The cavity pressure is 1Pa, the power is 100w, the etching time is 10min, and the etching depth is 1500nm; si for etching the chamfer layer 7 3 N 4 Etching with reactive ion beam (SF) as etching gas 6 、O 2 And N 2 Wherein SF 6 And O 2 The gas flow ratio of the chamfer angle structure layer 2-1 is 3: 1, the cavity pressure is 1Pa, the power is 20w, the etching time is 15s, and the inclination angle of the chamfer angle structure layer 2-1 is about 55 degrees;
removing the residual first photosensitive layer 8-1, soaking the substrate 1 in acetone until the first photosensitive layer 8-1 falls off, washing with deionized water and drying the substrate 1;
preparing a high-reflectivity film layer 11, and plating a layer of Ag on the surface layer of the substrate 1 by magnetron sputtering, wherein the thickness of the Ag layer is 10nm;
preparing a second photosensitive layer 8-2, and spin-coating a photoresist AR-1500 with the thickness of 500nm; the non-mark area 6 on the second mask 9-2 is a zigzag structure, the area of the inner circle is 201 μm x 41 μm, and the area of the outer circle is 400 μm x 240 μm; the second mask 9-2 also comprises a cross-shaped alignment mark matched with the first mask 9-1; the light blocking material on the second mask 9-2 is metal Cr with the thickness of 100nm, and the substrate is quartz; exposing the non-mark area 6 on the second mask 9-2 to the second photosensitive layer 8-2 by adopting a contact exposure process; etching the unmarked area 6 after development, and adopting ion beam etching, wherein the etching time is 5min, and the rotation angle of the substrate is 15 degrees; the chamfering layer 7 and the high-reflectivity thin film layer 11 on the non-marking area 6 are etched cleanly at one time by adopting the method, then the non-marking area 6 on the substrate 1 is etched, and the etching depth of the non-marking area 6 (part of the substrate 1) is 500nm; and removing the residual second photosensitive layer 8-2, soaking the substrate in acetone until the second photosensitive layer 8-2 falls off, removing the residual high-reflectivity film layer 11 on the alignment structure 2-2, washing with deionized water and drying the substrate.
In this embodiment, the high-reflectivity film 11 is added in addition to the chamfer structure layer 2-1 and the non-mark region 6, and the high-reflectivity film 11 is added at the bottom and the side wall of the alignment structure 2-2, so that the contrast of the alignment structure 2-2 can be further improved.
Comparative example one:
the substrate 1 of the alignment mark structure of the present comparative example is a silicon-based material; preparing a first photosensitive layer 8-1 by adopting a spin coating mode, wherein the material model of the first photosensitive layer 8-1 is AR-P3170, and the thickness is 100nm; the light blocking layer on the first mask 9-1 is made of metal Cr, the thickness of the metal Cr is 100nm, and the substrate is quartz; the mark pattern on the first mask 9-1 is a grating with a period of 20 μm, the grating length is 40 μm, and the area of the mark pattern is 200 μm by 40 μm; exposing a mark pattern on the first mask 9-1 to the first photosensitive layer 8-1 by adopting contact photoetching; etching the alignment structure 2-2 after development by using a reactive ion beam etching (SF) as an etching gas 6 And CHF 3 The cavity pressure is 1Pa, the power is 100w, the etching time is 10min, and the etching depth is 1500nm; and removing the residual first photosensitive layer 8-1, soaking the substrate in acetone until residual glue of the first photosensitive layer 8-1 falls off, washing with deionized water and drying the substrate.
The alignment mark structure shown in fig. 1 is prepared in this comparative example, after the multilayer film 3 is prepared on the substrate with the alignment mark, since the multilayer film has uneven thickness at the edge of the alignment structure 2-2, the light 5-1 reflected by illuminating the surface of the multilayer film, the light 5-2 directly reflected by illuminating the substrate, the sum of irregularly scattered light reflections 5-3 at the edge of the mark area by illuminating, and the light 5-4 reflected by illuminating the inside of the multilayer film multiple times and reflected back to the air, which are alignment lights incident on the edge of the alignment mark, cannot be reflected perpendicularly in one direction, thereby causing the alignment signal to be unclear.
As shown in fig. 7, it was found that the contrast of the marking region without the non-marking region as the depression structure in this comparative example was low under the CCD camera, and the alignment mark could not be seen clearly; meanwhile, due to the fact that no chamfer structure layer exists, the definition of the grating mark edge is low, the grating mark edge cannot be identified, and further subsequent alignment work cannot be carried out.
Comparative example two:
the alignment mark structure of this comparative example was formed as follows:
the substrate 1 is a silicon-based material; the material of the chamfer layer 7 is Si 3 N 4 The thickness is 20nm, and the preparation method is magnetron sputtering coating;
preparing a first photosensitive layer 8-1 by adopting a spin coating mode, wherein the material model of the first photosensitive layer 8-1 is AR-P3170, and the thickness is 100nm; the material of the light-blocking layer on the first mask 9-1 is metal Cr, the thickness is 100nm, and the substrate is quartz; the mark pattern on the first mask 9-1 is a grating with a period of 20 μm, the length of the grating is 40 μm, and the area of the mark pattern is 200 μm by 40 μm; exposing a mark pattern on the first mask 9-1 to the first photosensitive layer 8-1 by adopting contact photoetching;
si of post-development etched chamfer layer 7 3 N4, etching by adopting reactive ion beams, wherein etching gas is SF 6 And O 2 The gas flow ratio is 5: 1, the cavity pressure is 1Pa, the power is 40w, the etching time is 20s, and the etching depth is 20nm; (ii) a Etching the alignment structure 2-2 by reactive ion beam etching with SF as etching gas 6 And CHF 3 The cavity pressure is 1Pa, the power is 100w, the etching time is 10min, and the etching depth is 1500nm; etching the chamfer layer 7 by reactive ion beam etching with SF as etching gas 6 、O 2 And N 2 Wherein SF 6 And O 2 The gas flow ratio of the chamfer angle structure layer 2-1 is 3: 1, the cavity pressure is 1Pa, the power is 20w, the etching time is 15s, and the inclination angle of the chamfer angle structure layer 2-1 is about 55 degrees; removing residual first photosensitive layer 8-1, soaking substrate 1 in acetone until first photosensitive layer 8-1 falls off, washing with deionized waterAnd the substrate 1 is dried.
The alignment mark structure prepared in this comparative example contains a chamfer structure layer but no non-mark region. As shown in fig. 8, it can be found that the contrast of the mark region without the non-mark region as the recess structure is low under the CCD camera, and the alignment mark cannot be seen clearly, thereby affecting the subsequent alignment work.
Comparative example three:
the alignment mark structure of this comparative example was formed as follows:
the substrate 1 is a silicon-based material; preparing a first photosensitive layer 8-1 by adopting a spin coating mode, wherein the material model of the first photosensitive layer 8-1 is AR-P3170, and the thickness is 100nm;
the light blocking layer on the first mask 9-1 is made of metal Cr, the thickness of the metal Cr is 100nm, and the substrate is quartz; the mark pattern on the first mask 9-1 is a grating with the period of 20 μm, the length of the grating is 40 μm, and the area of the mark pattern is 200 μm by 40 μm; a mark for coarse alignment is also arranged on the first mask 9-1, the shape of the mark is cross-shaped, and the width of the mark is 10 mu m; exposing a mark pattern on the first mask 9-1 to the first photosensitive layer 8-1 by adopting contact photoetching; etching the alignment structure 2-2 by using a reactive ion beam etching (SF) as an etching gas 6 And CHF 3 The cavity pressure is 1Pa, the power is 100w, the etching time is 10min, and the etching depth is 1500nm;
removing the residual first photosensitive layer 8-1, soaking the substrate 1 in acetone until the first photosensitive layer 8-1 falls off, washing with deionized water, and drying the substrate 1; preparing a second photosensitive layer 8-2, and spin-coating a photoresist AR-P3170 with the thickness of 100nm; the non-marking area 6 on the second mask 9-2 is a zigzag structure, the area of the inner circle is 201μm 41 μm, and the area of the outer circle is 400 μm 240 μm; the second mask 9-2 also comprises a cross-shaped alignment mark matched with the first mask 9-1 for coarse alignment, the light blocking material on the second mask 9-2 is metal Cr, the thickness is 100nm, and the substrate is quartz;
exposing the non-mark area 6 on the second mask 9-2 to the second photosensitive layer 8-2 by adopting a contact exposure process; etching the unmarked region 6 after development by reactive ion beam etching with SF as etching gas 6 And CHF 3 The cavity pressure is1Pa, 50w of power, 3min of etching time and 500nm of etching depth; and removing the residual second photosensitive layer 8-2, soaking the substrate 1 by using acetone until the second photosensitive layer 8-2 falls off, washing by using deionized water, and drying the substrate 1.
The alignment mark structure prepared by the comparative example does not include the chamfer structure layer, but only includes the non-mark region. After the multilayer film 3 is prepared on the substrate of the alignment mark structure, light rays which are illuminated inside the multilayer film and reflected back to the air for multiple times cannot be reflected vertically along one direction, so that an alignment signal is unclear. As shown in fig. 9, it can be found that the grating mark edge of the alignment mark structure without the chamfer structure layer has low definition, and the grating mark edge cannot be identified, so that the subsequent alignment work cannot be performed.
The alignment mark has clear edge and contrast under an alignment detection system by optimizing the structure and the layout of the alignment mark, so that the detection capability of an alignment signal is improved, the distortion of the alignment signal is reduced, and the aim of reducing the alignment error in IC manufacturing is fulfilled.
The above-mentioned embodiments are intended to illustrate the objects, aspects and advantages of the present disclosure in further detail, and it should be understood that the above-mentioned embodiments are only illustrative of the present disclosure and are not intended to limit the present disclosure, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present disclosure should be included in the protection of the present disclosure.

Claims (10)

1. An alignment mark structure, comprising:
a substrate (1);
a marking region (2) comprising an alignment structure (2-2) and a chamfer structure layer (2-1); the alignment structure (2-2) is formed in the substrate (1) and is a concave structure; the chamfer structure layer (2-1) is formed on the surface of the substrate (1) and is of a convex structure, and the chamfer structure layer (2-1) forms a convex chamfer structure at the edge of the alignment structure (2-2);
and the non-marking region (6) is arranged around the periphery of the marking region (2), and the upper surface of the non-marking region (6) is lower than the lower surface of the chamfer structure layer (2-1) in the marking region (2).
2. The alignment mark structure of claim 1, wherein the bottom and the sidewalls of the alignment structure (2-2) are provided with a high reflectivity thin film layer (11);
the thickness of the high-reflectivity thin film layer (11) is not more than 100nm, and the high-reflectivity thin film layer is made of one of Au, al and Ag.
3. The alignment mark structure of claim 1, wherein the planar dimension of the alignment structure (2-2) is in the range of 0.5-50 μm, and the recess depth of the alignment structure (2-2) is in the range of 100-4000 nm.
4. The alignment mark structure of claim 3, wherein said alignment structure (2-2) comprises one of a cross-shaped alignment mark, a grid-type alignment mark.
5. The alignment mark structure of claim 1, wherein the thickness of the chamfer structure layer (2-1) is not more than 100nm, and the inclination angle of the chamfer structure is 35-55 °;
the chamfer structure layer (2-1) is made of a non-transparent medium which is easy to etch and control and comprises one of silicon nitride, aluminum nitride, silicon carbide and polycrystalline silicon.
6. The alignment mark structure of claim 3, wherein the non-mark region (6) is a zigzag structure and is disposed around the alignment structure (2-2) within a range of 1-1000 μm;
the non-mark area (6) is formed in the substrate (1) through etching, and the etching depth of the non-mark area does not exceed 1/2 of the depth of the concave structure.
7. A method for preparing an alignment mark structure according to any one of claims 1 to 6, comprising:
s1, forming a chamfer layer (7) on a substrate (1);
s2, coating a first photosensitive layer (8-1); etching the mark region (2) after exposure and development, wherein the chamfering layer (7) and the substrate (1) are etched in sequence to obtain an alignment structure (2-2);
s3, etching the chamfer layer (7) at the edge of the alignment structure (2-2) to obtain a convex chamfer structure, and removing the first photosensitive layer (8-1);
s4, coating a second photosensitive layer (8-2); etching the periphery of the mark region (2) after exposure and development, wherein the chamfering layer (7) and the substrate (1) are etched in sequence to obtain a non-mark region (6) and a chamfering structure layer (2-1);
and S5, removing the second photosensitive layer (8-2) to obtain a target alignment mark structure.
8. The method for preparing an alignment mark structure according to claim 7, further comprising after the step S3:
s31, depositing a high-reflectivity film layer (11), wherein the deposited thickness is not more than 100nm.
9. The method for preparing an alignment mark structure according to claim 8, wherein the step S5 further comprises:
and removing the high-reflectivity thin film layer (11) on the chamfer structure layer (2-1).
10. The method for preparing an alignment mark structure of claim 7, wherein the etching method in S3 is dry etching, the dry etching includes one of reactive ion etching and inductively coupled plasma etching, and the etching gas includes SF 6 、O 2 、N 2 、CHF 3 、Cl 2 Ar and C 4 F 8 One of (1);
the inclination angle of the convex chamfer structure obtained by etching is 35-55 degrees.
CN202211147128.1A 2022-09-20 2022-09-20 Alignment mark structure and forming method thereof Pending CN115440707A (en)

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