Alignment photoetching eccentricity correction method, preparation method of product wafer and multilayer bonding wafer

Abstract

The invention relates to the field of micro electro mechanical systems, in particular to an alignment photoetching eccentricity correction method, a preparation method of a product wafer and a multi-layer bonding wafer. The eccentricity correction method comprises the step of providing a photoetching plate with a preset pattern and a correction plate with a preset pattern, wherein the position of the preset pattern on the correction plate is accurate. The photoetching plate is arranged on a mask table of an alignment photoetching machine, the correction plate is arranged on a workbench of the alignment photoetching machine, and the positions of the preset patterns on the photoetching plate and the correction plate correspond to each other through an automatic alignment system and a moving assembly of the alignment photoetching machine. And replacing the positions of the target wafers with the same size so as to correspond to the position of the photoetching plate. According to the method, the existing alignment photoetching machine is used for photoetching, so that the advantage of high alignment photoetching efficiency is kept, the eccentricity between the photoetching plate and the target wafer is reduced, and the method has relatively high universality and practicability.

Description

Technical Field

[0001] The invention relates to the field of micro-electromechanical systems, and in particular to a method for correcting eccentricity in an aligned photolithography process, a method for preparing a product wafer, and a multi-layer bonded wafer. Background Art

[0002] Aligner lithography is a process that uses precision optical equipment to accurately transfer the pattern on the mask to a silicon wafer or other substrate. It involves using a light source (usually ultraviolet light) to illuminate a substrate coated with a photosensitive material through a mask, causing the photosensitive material to undergo chemical changes in the illuminated area, thereby forming the desired pattern. The aligner lithography machine realizes the positioning of the wafer by identifying the edge of the wafer. However, this positioning has a large error, resulting in the position of the pattern on the wafer often being offset. Since the etching of the wafer often has multiple layers, and the alignment of the upper layer is achieved by identifying the alignment marks formed on the lower layer, a small offset in the position of the pattern in the bottom layer does not affect the overall structure. However, with the development and popularization of wafer bonding technology, etched wafers are often used for bonding with other wafers. After the wafers obtained by alignment lithography are bonded, the position of the pattern on the two layers of wafers is offset due to the error in the position of the pattern on the wafer, which has an adverse effect on the structural function of the wafer.

[0003] At present, for etching of wafers that need to be bonded later, a stepper lithography machine is usually used for lithography to prevent the position of the pattern from shifting. However, the production efficiency of etching wafers with a stepper lithography machine is low and it is difficult to meet the needs of mass production. Summary of the invention

[0004] The purpose of the present invention is to provide a method for correcting eccentricity of an alignment photolithography pattern, a method for preparing a product wafer and a multi-layer bonded wafer for preventing eccentricity of an alignment photolithography pattern.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A method for correcting eccentricity of an aligned photolithography process, comprising:

[0007] Providing a photolithography plate having a preset pattern formed thereon and a correction plate having the preset pattern formed thereon, wherein when the correction plate is arranged relative to the photolithography plate, the position of the preset pattern on the correction plate corresponds to the position of the preset pattern on the photolithography plate;

[0008] The photolithography plate is placed on the mask stage of an alignment photolithography machine, and the correction plate is placed on the working table of the alignment photolithography machine, and the positions of the preset patterns on the photolithography plate and the correction plate are made to correspond to each other through the automatic alignment system and the moving component of the alignment photolithography machine;

[0009] The positions of the mask stage and the workbench are kept unchanged, the correction plate is disassembled, and a target wafer having the same size as the correction plate is set on the workbench so that the position of the target wafer corresponds to that of the photolithography plate.

[0010] Optionally, the photoresist plate is arranged on a mask stage of an alignment photolithography machine, the correction plate is arranged on a working table of the alignment photolithography machine, and the positions of the preset patterns on the photoresist plate and the correction plate are made relative to each other through an automatic alignment system and a moving component of the alignment photolithography machine, comprising:

[0011] The photolithography plate is placed on the mask stage of the alignment photolithography machine, and the preset pattern on the photolithography plate is identified by the automatic alignment system and recorded as a first image;

[0012] The correction plate is placed on the workbench of the alignment photolithography machine, and the preset pattern on the correction plate is identified by the automatic alignment system and recorded as a second image;

[0013] The offset is calculated with reference to the first image and the second image, and the position of the workbench is adjusted by the moving component according to the offset.

[0014] Optionally, the polarity of the preset pattern on the correction plate is opposite to the polarity of the preset pattern on the photolithography plate.

[0015] Optionally, after movement and correction, the positional offset between the center of the photolithography plate and the center of the correction plate is smaller than the minimum moving distance of the workbench.

[0016] Optionally, the correction plate is prepared by a stepper photolithography machine.

[0017] Optionally, the correction plate is arranged in a direction such that the side on which the preset pattern is formed faces a camera of the automatic alignment system.

[0018] In a second aspect, the present invention further provides a method for preparing a product wafer, characterized in that it comprises making the position of the target wafer correspond to the position of the photomask by the above method, and further comprises:

[0019] The product wafer is obtained by etching the surface of the target wafer with the photolithography plate located opposite to the target wafer.

[0020] Optionally, a pattern etched on the product wafer is used as a target pattern, and the target pattern includes the preset pattern.

[0021] In a third aspect, the present invention further provides a multi-layer bonded wafer, characterized in that it is obtained by aligning and bonding a plurality of stacked product wafers, and at least one of the product wafers is prepared by the above-mentioned preparation method.

[0022] According to the first aspect of the present invention, a correction plate with a precise preset pattern position is formed, and the projection of the preset pattern on the correction plate and the reticle is obtained by an automatic alignment system, and the offset is calculated and the workbench is moved according to the offset, so that the position of the correction plate corresponds to that of the reticle. The correction plate is removed and a target wafer of the same size is placed on the workbench, so that the position offset between the target wafer and the reticle is reduced to a negligible range, thereby achieving correction of the pattern position.

[0023] Furthermore, the preset graphic positions on the photolithography plate and the correction plate are recorded by the automatic alignment system of the alignment photolithography machine itself, and the position offset is obtained by comparing the records to perform alignment correction. There is no need to change the structure of the existing alignment photolithography machine, and the method has good universality and practicality.

[0024] Furthermore, since the polarities of the preset patterns on the correction plate and the photolithography plate are opposite, it is easy to distinguish the first image and the second image, and to perform subsequent movement correction according to the position offset between the two, thereby reducing the risk of confusing image data and transferring the wrong direction.

[0025] Furthermore, by preparing the correction plate using a stepper lithography machine, the accuracy of the preset pattern on the correction plate can be ensured, which helps to improve the correction accuracy.

[0026] According to the second aspect of the present invention, after correcting the position deviation between the photomask and the target wafer, the product wafer is obtained by alignment lithography, which helps to obtain a wafer with higher graphic position accuracy and has higher production efficiency, helping to reduce production costs.

[0027] Furthermore, at least part of the target pattern is used as a preset pattern for calibration, so that no pattern other than the target pattern is formed on the product wafer, which helps to ensure that the product wafer structure is the same as the preset. Taking only part of the target pattern as the preset pattern helps to reduce the production cost of the correction lens and improve efficiency.

[0028] According to the third aspect of the present invention, a multi-layer bonded wafer is obtained by bonding a product wafer with accurate graphic position, which helps to ensure that the structure of the multi-layer bonded wafer is accurate and the function is normal.

[0029] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a flow chart of the method for correcting eccentricity of in-place photolithography shown in the first embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of a method for setting up a photolithography plate and a correction plate shown in Embodiment 1 of the present invention.

[0032] Legend: 101-preset pattern, 1-photolithography plate, 2-mask stage, 3-correction plate, 31-pattern surface, 4-workbench, 5-camera. DETAILED DESCRIPTION

[0033] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0035] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0037] See also Figure 1 The method for correcting eccentricity of in-place photolithography claimed in the present invention comprises:

[0038] S110, providing a photolithography plate 1 formed with a preset pattern 101 and a correction plate 3 formed with the preset pattern 101, when the correction plate 3 is arranged relative to the photolithography plate 1, the position of the preset pattern 101 on the correction plate 3 corresponds to the position of the preset pattern 101 on the photolithography plate 1.

[0039] S120, set the photolithography plate 1 on the mask stage 2 of the alignment photolithography machine, set the correction plate 3 on the working table 4 of the alignment photolithography machine, and make the positions of the preset patterns 101 on the photolithography plate 1 and the correction plate 3 correspond to each other through the automatic alignment system and moving components of the alignment photolithography machine.

[0040] S130, keeping the positions of the mask stage 2 and the workbench 4 unchanged, dismantling the correction plate 3, and setting the target wafer with the same size as the correction plate 3 on the workbench 4, so that the position of the target wafer corresponds to that of the photolithography plate 1.

[0041] By forming a correction plate 3 with a precise position of the preset pattern 101, and obtaining the projection of the preset pattern 101 on the correction plate 3 and the photomask 1 through the automatic alignment system, the offset is calculated and the workbench 4 is moved according to the offset, so that the position of the correction plate 3 corresponds to that of the photomask 1. The correction plate 3 is removed and a target wafer of the same size is placed on the workbench 4, so that the position offset between the target wafer and the photomask 1 is reduced to a negligible range, thereby achieving correction of the pattern position.

[0042] In some embodiments, step S120 includes:

[0043] S121, placing the photolithography plate 1 on the mask stage 2 of the alignment photolithography machine, identifying the preset pattern 101 on the photolithography plate 1 through the automatic alignment system, and recording it as the first image.

[0044] S122, setting the correction plate 3 on the workbench 4 of the alignment photolithography machine, identifying the preset pattern 101 on the correction plate 3 through the automatic alignment system, and recording it as the second image.

[0045] S123, referring to the first image and the second image, calculating the offset, and adjusting the position of the workbench 4 by moving the components according to the offset.

[0046] The automatic alignment system of the alignment lithography machine itself is used to record the position of the preset graphics 101 on the lithography plate 1 and the correction plate 3, and the position offset is obtained by comparing the records to perform alignment correction. There is no need to change the structure of the existing alignment lithography machine, and it has good universality and practicality.

[0047] In some embodiments, the offset between the center of the corrected photolithography plate 1 and the center of the correction plate 3 is less than the minimum moving distance of the workbench 4, and the workbench 4 is moved to make the first image and the second image as close to overlapping as possible.

[0048] Please refer to the following examples for details.

[0049] Embodiment 1:

[0050] See also Figure 1 The multi-layer bonded wafer shown in a preferred embodiment of the present application is obtained by aligning and bonding a layer of etched product wafer and another unetched silicon wafer, the diameter of the product wafer is equal to that of the silicon wafer, and the silicon wafer covers the cavity etched on the surface of the product wafer. The preparation method of the product wafer in this embodiment includes:

[0051] S1. Make the target wafer and the photomask 1 correspond to each other.

[0052] S2. Etching is performed on the surface of the target wafer through a photomask 1 which is located opposite to the target wafer to obtain a product wafer.

[0053] In step S1, a target pattern to be etched on a target wafer is formed on a photoresist plate 1. To ensure that the positions of the target wafer and the photoresist plate 1 correspond to each other, eccentricity correction is required. The method includes:

[0054] S110, providing a photolithography plate 1 formed with a preset pattern 101 and a correction plate 3 formed with the preset pattern 101, when the correction plate 3 is arranged relative to the photolithography plate 1, the position of the preset pattern 101 on the correction plate 3 corresponds to the position of the preset pattern 101 on the photolithography plate 1.

[0055] S120, set the photolithography plate 1 on the mask stage 2 of the alignment photolithography machine, set the correction plate 3 on the working table 4 of the alignment photolithography machine, and make the positions of the preset patterns 101 on the photolithography plate 1 and the correction plate 3 correspond to each other through the automatic alignment system and moving components of the alignment photolithography machine.

[0056] S130, keeping the positions of the mask stage 2 and the workbench 4 unchanged, dismantling the correction plate 3, and setting the target wafer with the same size as the correction plate 3 on the workbench 4, so that the position of the target wafer corresponds to that of the photolithography plate 1.

[0057] In step S110 , the correction plate 3 is prepared by a stepper lithography machine with a complete target pattern as the preset pattern 101 , and the polarity of the preset pattern 101 on the correction plate 3 is opposite to the polarity of the preset pattern 101 on the lithography plate 1 .

[0058] Step S120 includes:

[0059] S121, placing the photolithography plate 1 on the mask stage 2 of the alignment photolithography machine, identifying the preset pattern 101 on the photolithography plate 1 through the automatic alignment system, and recording it as the first image.

[0060] S122, setting the correction plate 3 on the workbench 4 of the alignment photolithography machine, identifying the preset pattern 101 on the correction plate 3 through the automatic alignment system, and recording it as the second image.

[0061] S123, referring to the first image and the second image, calculating the offset, and adjusting the position of the workbench 4 by moving the components according to the offset.

[0062] See also Figure 2 In step S122, the correction plate 3 is arranged in a direction such that the pattern surface 31 formed with the preset pattern 101 faces the camera 5 of the automatic alignment system, so that the camera 5 can directly capture the preset pattern 101 on the pattern surface 31 to form a second image. In this embodiment, the camera 5 is arranged below the workbench 4, and the mask stage 2 is arranged above the workbench 4.

[0063] In step 123, since the polarities of the patterns on the photolithography plate 1 and the correction plate 3 are different, the first image and the second image are easily distinguished. The image is processed by the automatic alignment system to obtain the offset of the second image relative to the first image. In this embodiment, the moving component of the alignment lithography machine drives the workbench 4 to move and fine-tune, and the minimum moving distance is 1 mm. By moving the workbench 4, the positions of the first image and the second image are nearly overlapped, and the offset between the two is less than 1 mm.

[0064] In step S130, by keeping the position of the photomask 1 unchanged and replacing the position of the correction plate 3 with the target wafer, the positional offset between the photomask 1 and the target wafer is made less than 1 mm. At this time, the offset is small and can be ignored, that is, the positions of the photomask 1 and the target wafer correspond. The target wafer is a single-throw silicon wafer.

[0065] In step S2, photolithography is completed through an exposure operation, so that a preset pattern 101 is formed on the surface of the target wafer to form a product wafer.

[0066] Since the multi-layer bonded wafer in this embodiment is an industrial mass-produced structure, the product wafer needs to be produced in large quantities. After the preparation of a product wafer is completed, there is no need to re-correct it. Only a new target wafer needs to be taken to replace the prepared product wafer for re-etching, which has high production efficiency.

[0067] Embodiment 2:

[0068] The only difference between this embodiment and the first embodiment is that in this embodiment, only a part of the target graphics is taken as the preset graphics 101.

[0069] Embodiment three:

[0070] The only difference between this embodiment and the first embodiment is that the multi-layer bonded wafer in this embodiment includes multi-layer product wafers, and the target patterns of the product wafers are different, and eccentricity correction and preparation need to be performed separately.

[0071] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0072] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for correcting eccentricity in alignment photolithography, characterized in that: include: A photolithography plate (1) formed with a preset pattern (101) and a correction plate (3) formed with the preset pattern (101) are provided, wherein when the correction plate (3) and the photolithography plate (1) are arranged relative to each other, the position of the preset pattern (101) on the correction plate (3) corresponds to the position of the preset pattern (101) on the photolithography plate (1); The photolithography plate (1) is arranged on a mask stage (2) of an alignment photolithography machine, the correction plate (3) is arranged on a working stage (4) of the alignment photolithography machine, and the positions of the preset patterns (101) on the photolithography plate (1) and the correction plate (3) are made to correspond to each other through an automatic alignment system and a moving component of the alignment photolithography machine; The positions of the mask stage (2) and the workbench (4) are kept unchanged, the correction plate (3) is disassembled, and a target wafer having the same size as the correction plate (3) is set on the workbench (4) so ​​that the position of the target wafer corresponds to that of the photolithography plate (1).

2. The method according to claim 1, characterized in that The photolithography plate (1) is arranged on a mask stage (2) of an alignment photolithography machine, the correction plate (3) is arranged on a working stage (4) of the alignment photolithography machine, and the positions of the preset patterns (101) on the photolithography plate (1) and the correction plate (3) are made relative to each other through an automatic alignment system and a moving component of the alignment photolithography machine, comprising: The photolithography plate (1) is placed on a mask stage (2) of an alignment photolithography machine, and the preset pattern (101) on the photolithography plate (1) is identified by the automatic alignment system and recorded as a first image; The correction plate (3) is placed on a workbench (4) of an alignment photolithography machine, and the preset pattern (101) on the correction plate (3) is identified by the automatic alignment system and recorded as a second image; The offset is calculated by referring to the first image and the second image, and the position of the workbench (4) is adjusted by the moving component according to the offset.

3. The method according to claim 2, characterized in that The polarity of the preset pattern (101) on the correction plate (3) is opposite to the polarity of the preset pattern (101) on the photolithography plate (1).

4. The method according to claim 2, characterized in that After the movement and correction, the positional offset between the center of the photolithography plate (1) and the center of the correction plate (3) is less than the minimum moving distance of the workbench (4).

5. The method according to claim 1, characterized in that The correction plate (3) is prepared by a stepper photolithography machine.

6. The method according to claim 1, characterized in that The correction plate (3) is arranged in a direction such that the side surface on which the preset pattern (101) is formed faces the camera (5) of the automatic alignment system.

7. A method for preparing a product wafer, characterized in that: The method comprises making the target wafer correspond to the position of the photomask (1) by the method according to any one of claims 1 to 6, and further comprising: The product wafer is obtained by etching the surface of the target wafer with the photolithography plate (1) located opposite to the target wafer.

8. The preparation method according to claim 7, characterized in that: The pattern obtained by etching on the product wafer is used as a target pattern, and the target pattern includes the preset pattern (101).

9. A multi-layer bonded wafer, characterized in that: The product is obtained by aligning and bonding a plurality of stacked product wafers, and at least one of the product wafers is prepared by the preparation method as claimed in claim 7 or 8.

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