TWM615029U - Wafer with hierarchical edge - Google Patents

Abstract

The present invention is a wafer with a step-shaped crystal edge. The wafer includes a body and a protective layer. The main body is a round sheet body, and has an element surface and a back surface opposite to each other. The ring side surface surrounds between the back surface and the component surface, and one of the two opposite peripheral edges of the ring side surface connects the peripheral edge of the back surface. The level ring connects the periphery of the element surface and the other peripheral edge of the ring side. The level ring has a plurality of level surfaces. The distance between the level ring and the back surface gradually decreases from the periphery of the element surface to the second peripheral edge of the ring side. The protective layer is attached to the component surface and the class surface. Thereby, the contact area between the edge of the main body and the protective layer is relatively large, so that the protective layer is firmly attached to and supports the main body, which can improve the yield of the wafer during the subsequent thinning process of the backside of the wafer.

Description

Wafers with hierarchical edges

This creation relates to a wafer with a step-shaped ring groove and a step-shaped crystal edge formed by laser processing and cutting with a cutting tool before the crystal back thinning and polishing process.

With the evolution of world technology, the application of semiconductor technology has been completely integrated into human life. The wafers used in semiconductor technology include gallium arsenide wafers, silicon carbide wafers, silicon wafers, and so on. Since the semiconductor components on the front side of the wafer are composed of many different structures and materials, the thin film deposition process and the internal stress relief process in the junction of heterogeneous materials are important issues. Nowadays, semiconductor device epitaxy technology is used on heterogeneous wafers. Due to the material junction stress, large epitaxy manufacturers choose wafers with different wafer faces for the epitaxial device manufacturing process. The selection of different wafer surfaces makes the corner shapes of the wafers have various forms such as full bullnosed, arris edge, and reverse bevel.

In order to improve the performance of semiconductor devices, the wafer manufacturing process includes a backside thinning process. During the wafer back thinning process, adhesive tape or liquid adhesive material is applied to the front surface of the wafer to form a protective layer, and then the front surface of the wafer is supported by a polishing stage, and the back surface of the wafer is polished with a grinding wheel to reduce the size of the wafer. The thickness of the circle.

However, in the current wafer thinning process, the protective layer at the corners of the wafer (ie, the edge of the wafer) cannot firmly adhere to the surface of the wafer and support the wafer, resulting in uneven stress distribution when the grinding wheel is applied. The problem caused damage to the components on the front side of the wafer, and the thinning process of the backside of the wafer failed. When the edge shape of the crystal is edge or reverse slope, or when the semiconductor component material on the front side of the wafer is different from the silicon wafer, it is a heterogeneous junction and hard and brittle gallium nitride (GaN) material, the backside thinning process The failure rate is higher.

Therefore, the prior art wafer and its manufacturing method need to be improved.

In view of the aforementioned shortcomings and deficiencies of the prior art, the present invention provides a wafer with hierarchical crystal edges, which can improve the supporting effect of the protective layer at the crystal edges by using the hierarchical crystal edges to increase the process yield.

In order to achieve the above creative purposes, the technical means used in this creation is to design a wafer with a hierarchical crystal edge, which includes: A body, which is a round sheet body and has: Opposite an element surface and a back surface, the diameter of the element surface is smaller than the diameter of the back surface, and the peripheral edge of the element surface is a first side peripheral edge; A ring side surface, which surrounds between the back surface and the element surface; two opposite peripheral edges of the ring side surface are a second side peripheral edge and a third side peripheral edge respectively, and the third side peripheral edge is connected to the peripheral edge of the back surface; A step ring portion, which connects the first side periphery of the element surface and the second side periphery of the ring side; The first side peripheral edge of the element surface to the second side peripheral edge of the ring side surface are arranged in sequence; the distance between the step ring portion and the back surface is from the first side peripheral edge of the element surface toward the second side peripheral edge of the ring side surface The side periphery gradually shrinks in a class-like manner; A protective layer attached to the element surface of the main body and the step surface of the step ring.

The advantage of this creation is that the edge of the body has a step ring, which makes the edge of the body appear stepped. Compared with the bevel or arcuate corner shape of the existing wafer, the step ring can increase the contact area between the edge of the main body and the protective layer, so that the protective layer can be firmly attached and support the main body. In this way, when the wafer is undergoing the subsequent thinning process of the backside of the wafer, the force of the grinding wheel can be evenly distributed on the wafer, which can avoid damage to the components on the front side of the wafer and improve the yield of the backside thinning process.

Furthermore, for the wafer with step-shaped crystal edges, wherein: the width of the step ring portion is defined as the radial separation distance between the side surface of the ring and the first side peripheral edge of the element surface; The height is defined as the distance between the element surface and the second peripheral edge of the ring side surface in the thickness direction of the body; the width of the step ring portion is greater than or equal to the height of the step ring portion.

Furthermore, in the wafer with step-like crystal edges, the width of the step ring is between 50 and 200 microns; the height of the step ring is between 20 and 100 microns.

Furthermore, in the wafer with step-like crystal edges, the body includes: a silicon-based layer, wherein the side surface of the ring, the step ring portion and the back surface are located on the silicon-based layer; a gallium nitride layer, which Covering a side surface of the silicon-based layer opposite to the back surface; wherein the device surface is a side surface of the gallium nitride layer opposite to the silicon-based layer.

Please refer to FIG. 7, the method for manufacturing a wafer with step-shaped crystal edges of the present invention includes the following steps: preparing a wafer S1, forming a step ring portion S2, forming a step-shaped crystal edge S3, and attaching a protective layer S4. The wafer of the present invention is a wafer prepared for the backside thinning process.

Prepare wafer: Please refer to FIG. 1. First, prepare a wafer, which has a round sheet-shaped body 10 with a front side 101 and a back side 102 opposite to each other. Specifically, the body 10 is a heterogeneous material, and includes a silicon-based layer 11 and a gallium nitride layer 12. The thickness of the silicon-based layer 11 is preferably 600 to 750 microns. The gallium nitride layer 12 is a hard and brittle material covering the surface of the silicon base layer 11, and its thickness is preferably 2 to 4 microns. The drawing is only for illustration and not drawn according to actual scale. The front side 101 and the back side 102 are sides of the gallium nitride layer 12 and the silicon-based layer 11 away from each other, respectively.

Forming a step ring: Please refer to FIG. 2 to cut a laser device A on the front surface 101 of the main body 10 to form a step ring 13. The step ring portion 13 is a ring groove and surrounds the center of the main body 10. At this time, the main body 10 is a wafer with a step ring groove. The class ring 13 has a plurality of class planes 131, and the class planes 131 and the front 101 face the same direction, and surround the center of the main body 10 in sequence. The so-called level surface 131 sequentially surrounds the center of the body 10, that is, the diameter of each level surface 131 is different, and the level surface 131 with a larger diameter surrounds the level surface 131 with a smaller diameter and is combined into a shape similar to an annual ring. The distance between the level ring portion 13 and the back surface 102 is gradually reduced toward the periphery of the front surface 101, that is, the distance between the level surface 131 and the back surface 102, which is farther from the center of the main body 10, is closer. The distance D1 between the step ring 13 and the side 14 of the main body 10 is preferably between 0.5 and 1.5 mm. In addition, in this embodiment, the laser device A penetrates the gallium nitride layer 12 on the surface of the main body 10 and forms a step ring 13 on the silicon base layer 11.

In this embodiment, the specific forming sequence of the step ring portion 13 is as follows: First, fix the radial distance between the laser device A and the periphery of the front surface 101 (that is, fix the distance between the laser device A and the center of the front surface 101), and use the laser The device A is cut to form the step surface 131 of the step ring 13 closest to the center of the front 101. When cutting, the body 10 can be fixed and the fixed laser device A can be moved around the center of the front 101, or the laser device A can be fixed and the body 10 can be rotated. Either way. Then, the laser device A is moved toward the periphery of the front surface 101 to reduce the radial distance between the laser device A and the periphery of the front surface 101 and form another level surface 131.

Please refer to FIG. 5, when the width of the step surface is narrow, the specific cutting steps of the laser device A are as follows: first align the laser device A with the first alignment line L1 to cut the first step surface 1311A, and then Move the laser device A toward the periphery of the front surface 101 to align the laser device A with the second alignment line L2 to cut a second level surface 1312A.

Please refer to FIG. 6, when the width of the step surface is relatively wide, the laser device A can also be moved toward the periphery of the front surface 101 multiple times to form a single step surface. Specifically, first align the laser device A with the first alignment line L1A to cut out the inner ring of the first step surface 1311B, and then move the laser device A toward the periphery of the front surface 101 to align the laser device A with the first alignment line L1A. Align the line L2A to cut the outer ring of the first level surface 1311B, and then continue to move the laser device A to form other level surfaces.

Form the step-like crystal edge: please refer to 2 and Figure 3, use a cutter (not shown in the figure) to cut off the main body 10 outside the step ring 13 so that the step ring 13' is located at the edge of the main body 10'. The body 10' after cutting is still a round sheet body, and has an element surface 101' and a back surface 102' opposite to each other. The element surface 101' is the part remaining after the front surface 101 is cut off, and specifically is a side surface of the gallium nitride layer 12' opposite to the silicon base layer 11', and the diameter of the element surface 101' is smaller than the diameter of the back surface 102'; The periphery of 101' is a first side periphery 121'. A ring side surface 103' of the main body 10' surrounds between the back surface 102' and the element surface 101'. The two opposite peripheral edges of the ring side surface 103' are respectively a second side peripheral edge 1032' and a third side peripheral edge 1031', and the third side peripheral edge 1031' is connected to the peripheral edge of the back surface 102'.

The shape of the step ring portion 13' after cutting is substantially the same as that before cutting. The only difference is that the outer groove wall surface of the step ring portion 13 is cut off by the cutter during the cutting process. The step ring portion 13' connects the first side peripheral edge 121' of the element surface 101' and the second side peripheral edge 1032' of the ring side surface 103'; each step surface 131 of the step ring portion 13' is from the first side peripheral edge of the element surface 101' 121' to the second side peripheral edge 1032' of the ring side 103' are arranged in sequence; the distance between the step ring portion 13' and the back side 102' is gradually tapered from the first side peripheral edge 121' to the second side peripheral edge 1032'.

Attach a protective layer: please refer to Figure 4, attach a protective layer 20 on the component surface 101' and the level ring portion 13' of the main body 10', and the protective layer 20 covers the component surface 101' and the level ring portion 13 'The class aspect 131. The protective layer 20 is preferably an adhesive tape and has a thickness of about 165 microns.

Please refer to Figure 3 for cooperation. In addition, in order to further enhance the attachment condition of the protective layer 20 and the corner knife cutting strength of the body 10, the preferred shape of the aforementioned step ring portion 13' is as follows: the width of the step ring portion 13' W1 is defined as the radial separation distance between the ring side surface 103' and the first side peripheral edge 121' of the element surface 101'; the height H1 of the step ring portion 13' is defined as the second side peripheral edge 1032 of the element surface 101' and the ring side surface 103' 'In the thickness direction of the main body 10'; in this embodiment, the width W1 of the step ring portion 13' is greater than or equal to the height H1 of the step ring portion 13', and the width W1 of the step ring portion 13' is between 50 to Between 200 micrometers, the height H1 of the step ring 13' is between 20 to 100 micrometers. In addition, the width W2 of each level surface 131 is preferably between 10 and 50 microns, and the height difference H2 of adjacent two level surfaces 131 is preferably between 10 and 50 microns. The drawings of all the class rings in this creation are only for reference, and are not drawn according to the actual scale.

The wafer with step-shaped crystal edges of the present invention is the wafer produced by the aforementioned method, and its structure has been described in the aforementioned production steps, so it will not be repeated here.

In summary, in the present invention, a stepped ring 13' is designed on the edge of the body 10' to make the edge of the body appear stepped, thereby increasing the contact area between the edge of the body and the protective layer 20, so that the protective layer 20 is firmly attached The edge of the main body 10' supports the main body 10' to improve the yield of the wafer during the subsequent thinning process of the backside of the wafer.

The above description is only the preferred embodiment of the creation, and does not limit the creation in any form. Although the creation has been disclosed in the preferred embodiment as above, it is not intended to limit the creation. Any technical field has Generally knowledgeable persons, without departing from the scope of this creative technical solution, can use the technical content disclosed above to make slight changes or modifications to equivalent embodiments with equivalent changes. However, any content that does not deviate from this creative technical solution is based on this Any simple modifications, equivalent changes and modifications made to the above embodiments by the technical essence of the creation still fall within the scope of the technical solution for creation.

10: body 101: front 102: back 11: Silicon base layer 12: Gallium nitride layer 13: Class Ring Department 131: Class side 1311: first class aspect 1312: second class aspect 14: side 20: protective layer L1: first alignment L2: second alignment 1311A: First class aspect 1312A: First class aspect 1311B: First class aspect L1A: first alignment L2A: second alignment 10’: body 101’: component side 102’: Back 103’: Ring side 1031’: Third side perimeter 1032’: Second side perimeter 11’: Silicon base layer 12’: Gallium nitride layer 121’: First side perimeter 13’: Class Circle Department H1: height W1: width H2: height difference W2: width A: Laser device

FIG. 1 is a schematic diagram of the wafer preparation steps of the method for manufacturing a wafer with a step-shaped crystal edge created by the invention. FIG. 2 is a schematic diagram of the steps of forming a step ring in the method for manufacturing a wafer with a step-shaped crystal edge created. FIG. 3 is a schematic diagram of the step of forming the step-shaped crystal edge in the method for manufacturing the created step-shaped crystal edge wafer. FIG. 4 is a schematic diagram of the steps of attaching a protective layer in the method for manufacturing a wafer with a step-shaped crystal edge created. FIG. 5 is a schematic diagram of a second embodiment of the step of forming a step ring in the method for manufacturing a wafer with a step-shaped crystal edge created. FIG. 6 is a schematic diagram of a third embodiment of the step of forming a step ring in the method for manufacturing a wafer with step-shaped crystal edges created. Fig. 7 is a flowchart of a method for manufacturing a wafer with a step-shaped crystal edge created.

10’: body

101’: component side

102’: Back

103’: Ring side

1031’: Third side perimeter

1032’: Second side perimeter

11’: Silicon base layer

12’: Gallium nitride layer

121’: First side perimeter

13’: Class Circle Department

131: Class side

H1: height

W1: width

H2: height difference

W2: width

Claims (4)

A wafer with hierarchical crystal edges, including: A body, which is a round sheet body and has: Opposite an element surface and a back surface, the diameter of the element surface is smaller than the diameter of the back surface, and the peripheral edge of the element surface is a first side peripheral edge; A ring side surface, which surrounds between the back surface and the element surface; two opposite peripheral edges of the ring side surface are a second side peripheral edge and a third side peripheral edge respectively, and the third side peripheral edge is connected to the peripheral edge of the back surface; A step ring portion, which connects the first side periphery of the element surface and the second side periphery of the ring side; The first side peripheral edge of the element surface to the second side peripheral edge of the ring side surface are arranged in sequence; the distance between the step ring portion and the back surface is from the first side peripheral edge of the element surface toward the second side peripheral edge of the ring side surface The side periphery gradually shrinks in a class-like manner; A protective layer attached to the element surface of the main body and the step surface of the step ring. The wafer with hierarchical crystal edges as described in claim 1, in which: The width of the step ring portion is defined as the radial separation distance between the ring side surface and the first side peripheral edge of the element surface; The height of the step ring portion is defined as the distance between the element surface and the second side periphery of the ring side surface in the thickness direction of the body; The width of the step ring is greater than or equal to the height of the step ring. A wafer with hierarchical crystal edges as described in claim 2, in which: The width of the step ring is between 50 and 200 microns; The height of the step ring is between 20 and 100 microns. The wafer with hierarchical crystal edges as described in any one of claims 1 to 3, wherein: The ontology contains: A silicon-based layer, wherein the side surface of the ring, the level ring portion and the back surface are located on the silicon-based layer; A gallium nitride layer covers a side surface of the silicon-based layer opposite to the back surface; wherein the device surface is a side surface of the gallium nitride layer opposite to the silicon-based layer.

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