CN115332052A - Substrate processing method capable of reducing deformation stress and substrate - Google Patents

Substrate processing method capable of reducing deformation stress and substrate Download PDF

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Publication number
CN115332052A
CN115332052A CN202210977056.7A CN202210977056A CN115332052A CN 115332052 A CN115332052 A CN 115332052A CN 202210977056 A CN202210977056 A CN 202210977056A CN 115332052 A CN115332052 A CN 115332052A
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Prior art keywords
wafer
grooves
substrate
groove
deformation stress
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李志宇
周志豪
王云云
黄建烽
李贤途
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Fujian Jingan Optoelectronics Co Ltd
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Fujian Jingan Optoelectronics Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02002—Preparing wafers
    • H01L21/02005—Preparing bulk and homogeneous wafers
    • H01L21/02008—Multistep processes
    • H01L21/0201—Specific process step
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02002—Preparing wafers
    • H01L21/02005—Preparing bulk and homogeneous wafers
    • H01L21/02008—Multistep processes
    • H01L21/0201—Specific process step
    • H01L21/02013—Grinding, lapping
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02002—Preparing wafers
    • H01L21/02005—Preparing bulk and homogeneous wafers
    • H01L21/02008—Multistep processes
    • H01L21/0201—Specific process step
    • H01L21/02024—Mirror polishing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/20—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a particular shape, e.g. curved or truncated substrate

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  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Mechanical Treatment Of Semiconductor (AREA)

Abstract

The invention provides a substrate processing method capable of reducing deformation stress and a substrate, comprising the following steps: cutting the crystal bar into wafers, and grinding the wafers to improve the flatness of the wafers; utilizing a slotting component to open a plurality of first grooves parallel to a first direction on the first surface of the wafer, wherein the first direction is parallel to the flat edge direction of the wafer, the plurality of first grooves are arranged at intervals in a first radial direction of the wafer, and the plurality of first grooves are fully distributed on the first surface of the wafer along the first radial direction; utilizing the grooving component to open a plurality of second grooves perpendicular to the first grooves on the first surface of the wafer, wherein the second grooves are arranged at intervals in a second radial direction of the wafer, and the second grooves are distributed on the first surface of the wafer along the second radial direction; carrying out high-temperature annealing on the wafer provided with the first groove and the second groove; and polishing the second surface of the wafer provided with the first groove and the second groove by using polishing equipment. The method reduces the warpage and deformation of the wafer.

Description

Substrate processing method capable of reducing deformation stress and substrate
Technical Field
The invention relates to the technical field of semiconductor manufacturing, in particular to a substrate processing method capable of reducing deformation stress and a substrate.
Background
With the advancement of science and technology in the semiconductor industry, the demand for chips at home and abroad is continuously rising; in a competitive context, quality improvement and consistent product uniformity are critical. In the LED industry, the used sapphire substrate is processed by crystal cutting, grinding, polishing and the like, and when the sapphire crystal is cut, the diamond wire simultaneously generates the phenomena of brittle failure, crystal stress extrusion, interaction between changed ions and the like on a workpiece crystal bar, so that the surface shape is uneven, and the generated surface stress is difficult to eliminate; the method for eliminating the surface damage and stress residue of wire-electrode cutting is generally grinding. Grinding is divided into single-sided grinding and double-sided grinding; double-sided grinding occupies the main market and has the following advantages: high double-side processing efficiency, small grinding resistance, no damage to wafer workpieces, easy control of thickness tolerance of processed products and the like.
The double-sided grinding powder uses B4C (boron carbide) or SiC (silicon carbide) to achieve a certain removal amount, so that line cutting mark traces are removed, the thickness consistency can be improved, and the warping degree after cutting can be reduced; but the surface damage layer after grinding still has residual stress. The existing process technology flow can remove the surface stress by introducing an annealing mode, so that the stress on two surfaces is eliminated. However, after the copper polishing and polishing process is performed on the wafer, a large stress difference is generated between the polished surface and the unpolished surface of the wafer, so that the substrate wafer is bent or deformed, and the quality of the substrate is affected. Therefore, how to reduce the warpage and deformation of the wafer is an urgent technical problem to be solved.
Disclosure of Invention
Accordingly, the present invention is directed to a substrate processing method and a substrate capable of reducing deformation stress, so as to solve one or more of the problems of the prior art.
According to one aspect of the invention, the invention discloses a substrate processing method capable of reducing deformation stress, which comprises the following steps:
cutting a crystal bar into wafers, and grinding the wafers to improve the flatness of the wafers;
adsorbing a ground wafer on a vacuum seat on a carrier, and forming a plurality of first grooves parallel to a first direction on a first surface of the wafer by using a grooving component, wherein the first direction is parallel to the flat edge direction of the wafer, the plurality of first grooves are arranged at intervals in a first radial direction of the wafer, and the plurality of first grooves are fully distributed on the first surface of the wafer along the first radial direction;
utilizing the grooving component to open a plurality of second grooves perpendicular to the first grooves on the first surface of the wafer, wherein the second grooves are arranged at intervals in a second radial direction of the wafer, and the second grooves are distributed on the first surface of the wafer along the second radial direction;
carrying out high-temperature annealing on the wafer provided with the first groove and the second groove;
and polishing a second surface of the wafer provided with the first groove and the second groove by using polishing equipment, wherein the second surface is the surface of the wafer opposite to the first surface.
In some embodiments of the present invention, the grooved component is a grooved grinding wheel, the grooved grinding wheel includes a plurality of parallel and spaced abrasive rings, and each abrasive ring is sleeved on the outer circumferential surface of the grooved grinding wheel.
In some embodiments of the invention, the cross-sectional shape of the abrasive ring in a plane passing through the axis of the grooved wheel and the cross-sectional shapes of the first and second grooves are both trapezoidal.
In some embodiments of the present invention, the top width dimension of the trapezoid is in a range of 500 ± 20um, the bottom width dimension of the trapezoid is in a range of 1000um ± 20um, the height dimension of the trapezoid is in a range of 50 ± 20um, and the spacing between two adjacent abrasive rings of the grooved grinding wheel is in a range of 2300um ± 20um.
In some embodiments of the present invention, the,
utilizing a grooving component to open a plurality of first grooves parallel to a first direction on a first surface of the wafer, comprising:
rotating at a first rotating speed by using a slotting component and moving along a first direction so as to open a plurality of first grooves parallel to the first direction on the first surface of the wafer; and/or
Utilizing the grooving component to open a plurality of second grooves perpendicular to the first grooves on the first surface of the wafer, comprising:
the wafer is rotated by 90 degrees or 270 degrees, rotated at a first rotation speed by using a slotting component and moved along a first direction so as to open a plurality of second grooves which are vertical to the first grooves on the first surface of the wafer.
In some embodiments of the present invention, the first rotation speed range is 2000rpm to 2500rpm, and the grinding time per unit area ranges from 5 to 10 seconds.
In some embodiments of the present invention, the abrasive ring is nickel plated and a plurality of diamond particles are attached to a surface of the abrasive ring.
In some embodiments of the invention, grinding the wafer comprises:
and carrying out double-sided grinding on the wafer.
According to another aspect of the present invention, there is also provided a substrate capable of reducing deformation stress, wherein the substrate is processed by the substrate processing method capable of reducing deformation stress as claimed in any one of the above claims 1 to 8.
In some embodiments of the present invention, the number of the first trenches on the substrate is 33, and the number of the second trenches is 34.
The invention discloses a substrate processing method capable of reducing deformation stress and a substrate, wherein a plurality of first grooves and a plurality of second grooves are formed in the back surface (the surface facing the back of a polished surface) of a wafer by utilizing a slotting component, the first grooves and the second grooves are vertically arranged, and the plurality of first grooves and the plurality of second grooves are respectively distributed on the back surface of the wafer along a first radial direction and a second radial direction, namely the back surface of the wafer is divided into a plurality of unit cells by the first grooves and the second grooves; through the process steps, the stress on the back of the wafer is reduced in the polishing process, so that the uniformity of the stress of the polished surface and the unpolished surface of the wafer is ensured, the warping and deformation degree of the wafer is relieved, and the flatness of a finished substrate product is ensured.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
It will be appreciated by those skilled in the art that the objects and advantages that can be achieved with the present invention are not limited to the specific details set forth above, and that these and other objects that can be achieved with the present invention will be more clearly understood from the detailed description that follows.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. For purposes of illustrating and describing some portions of the present invention, corresponding parts of the drawings may be exaggerated, i.e., may be larger, relative to other components in an exemplary apparatus actually manufactured according to the present invention. In the drawings:
fig. 1 is a flow chart illustrating a method for processing a substrate capable of reducing a deformation stress according to an embodiment of the invention.
FIG. 2 is a flow chart of a substrate processing method for reducing deformation stress according to another embodiment of the present invention.
Fig. 3 is a schematic structural diagram of a slotted component according to an embodiment of the present invention.
FIG. 4 is a schematic view of a substrate with reduced deformation stress according to an embodiment of the present invention.
Fig. 5 is a partial structural schematic view of the substrate shown in fig. 4.
Fig. 6 is a partial SEM scanning electron micrograph of the substrate shown in fig. 5.
Fig. 7 is a schematic view of a notching apparatus for notching a substrate, according to one embodiment of the present invention.
Fig. 8a to 8d are graphs comparing the degree of bending and deformation of a substrate of the prior art and a substrate of the present invention during respective processes, respectively.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the embodiments of the present invention are further described in detail below with reference to the accompanying drawings. The exemplary embodiments and descriptions of the present invention are provided to explain the present invention, but not to limit the present invention.
It should be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and/or processing steps closely related to the scheme according to the present invention are shown in the drawings, and other details not closely related to the present invention are omitted.
It should be emphasized that the term "comprises/comprising/comprises/comprising" when used herein, is taken to specify the presence of stated features, elements, steps or components, but does not preclude the presence or addition of one or more other features, elements, steps or components.
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same reference numerals denote the same or similar components, or the same or similar steps.
Fig. 1 is a flowchart illustrating a substrate processing method for reducing a deformation stress according to an embodiment of the invention, and as shown in fig. 1, the substrate processing method for reducing a deformation stress at least includes steps S10 to S50.
Step S10: the method comprises the steps of cutting a crystal bar into wafers, and grinding the wafers to improve the flatness of the wafers.
In this step, the cutting of the boule into wafers may be performed by a boule cutting device, and specifically, the boule may be cut into wafer wafers by using a ring-shaped wafer saw blade having an inner diameter edge embedded with diamond particles. The edge of the wafer cut by the cutting machine is sharp, so that the edge shape and the outer diameter size of the wafer can be further modified in order to avoid the influence of corner chipping on the strength of the wafer, damage to the surface smoothness of the wafer and pollution particles to subsequent processes. The purpose of grinding is to remove saw cuts and damages generated on the surface of the wafer during cutting so as to enable the surface of the wafer to reach the required smoothness; grinding of the wafer is illustratively done on a wafer grinder. In this step, the polishing of the wafer may be single-side polishing or double-side polishing.
Step S20: the ground wafer is adsorbed on a vacuum seat on a carrying platform, a plurality of first grooves parallel to a first direction are formed in the first surface of the wafer through a grooving component, the first direction is parallel to the flat edge direction of the wafer, the first grooves are arranged at intervals in the first radial direction of the wafer, and the first grooves are distributed on the first surface of the wafer along the first radial direction.
Fig. 7 is a schematic view of a slotting apparatus for slotting a substrate according to an embodiment of the present invention, as shown in fig. 7, the slotting apparatus at least includes a carrier 200, a vacuum base 300 and a slotting part 100, the carrier 200 and the vacuum base 300 can be conventional apparatuses commonly used in the wafer 001 production at present, the vacuum base 300 is used for absorbing the wafer 001, and the carrier 200 can rotate around the axis thereof to adjust the angle of the wafer 001; in addition, the stage can also move in the X2 direction. In fig. 7, the slotted member 100 is positioned above the wafer 001. Illustratively, the grooving member 100 is a grooving grinding wheel, and in this case, the grooving grinding wheel located above the wafer 001 may not only rotate about its own axis but also move in a horizontal direction when grooving the wafer 001. It should be understood that when grooving the wafer, the grooving component can be other grooving components such as a grooving cutter besides the grooving grinding wheel.
Illustratively, the step of forming a plurality of first trenches parallel to a first direction in the first surface of the wafer using a grooving member includes: the grooving component rotates at a first rotating speed and moves along a first direction so as to open a plurality of first grooves parallel to the first direction on the first surface of the wafer. In this case, the first direction is a direction parallel to the first trench and the flat side of the wafer, and the first direction may be a horizontal direction.
Specifically, when the first groove is formed, the wafer is placed on the wafer bearing table, the flat edge direction of the wafer is adjusted to be parallel to the axis of the grooving grinding wheel, the grooving grinding wheel rotates around the axis of the grooving grinding wheel at the rotating speed of R1 (first rotating speed) to grind the wafer, and the grooving grinding wheel moves along the horizontal direction in the rotating process, so that the formation of the first groove is completed. Since the width of the grooved grinding wheel is generally smaller than the diameter of the wafer, the grooved grinding wheel undergoes a plurality of reciprocations to cause the plurality of first grooves to be distributed over the first surface of the wafer in the first radial direction of the wafer. In this step, the first radial direction may be understood as a direction perpendicular to the flat side of the wafer. And the plurality of first grooves are distributed on the first surface of the wafer, the distance between the outermost first grooves and the outer edge of the wafer is small enough, so that the distance is not enough to open one first groove.
Furthermore, the grooved grinding wheel comprises a plurality of grinding rings which are parallel to each other and are arranged at intervals, and the grinding rings are sleeved on the peripheral surface of the grooved grinding wheel. In this case, the grooved wheel with a plurality of abrasive rings can open a plurality of parallel first grooves on the first surface of the wafer in one reciprocating motion.
Step S30: and utilizing the grooving component to open a plurality of second grooves perpendicular to the first grooves on the first surface of the wafer, wherein the second grooves are arranged at intervals in a second radial direction of the wafer, and the second grooves are distributed on the first surface of the wafer along the second radial direction.
In this step, a plurality of second trenches are further formed on the first surface of the wafer, on which the first trenches are formed, and the direction of the second trenches is perpendicular to the direction of the first trenches, and then the direction of the second trenches is also perpendicular to the direction of the flat edge of the wafer. The second groove is similar to the first groove and is also opened through a grooving grinding wheel, preferably, the first groove and the second groove are opened by adopting the same grooving part, and the shape and the size of the first groove and the second groove are the same.
Specifically, when the second grooves are formed, the wafer is rotated by 90 degrees or 270 degrees through the carrying platform below the vacuum seat, at the moment, the flat edge on the wafer is perpendicular to the axis of the grooving grinding wheel, further, the grooving component is rotated at a first rotation speed, and the grooving grinding wheel moves along a first direction while rotating, so that a plurality of second grooves perpendicular to the first grooves are formed in the first surface of the wafer. Similarly, the grooving grinding wheel can make a plurality of second grooves fully distributed on the first surface of the wafer along the second radial direction of the wafer after reciprocating for a plurality of times; and the plurality of second grooves are distributed on the first surface of the wafer, so that the distance between the outermost second grooves and the corresponding outer edge of the wafer is small enough.
Step S40: and carrying out high-temperature annealing on the wafer provided with the first groove and the second groove.
In order to further reduce the residual stress of the wafer, after the first trench and the second trench are opened on the back surface of the wafer, the wafer is further annealed at a high temperature, and the annealing temperature used in this step may be 650 ℃.
In another embodiment, as shown in fig. 2, the wafer may be further edge chamfered before the high temperature annealing of the wafer having the first and second trenches. When the edge chamfering is carried out, the edge of the wafer can be specifically polished by a diamond grinding wheel, so that the edge of the wafer is blunt and smooth and is not easy to break.
Step S50: and polishing a second surface of the wafer provided with the first groove and the second groove by using polishing equipment, wherein the second surface is the surface of the wafer opposite to the first surface.
Polishing is an important process for processing a semiconductor wafer having a mirror surface by removing a mechanically damaged layer on the surface of the wafer by mechanical polishing, chemical polishing or chemical mechanical polishing. Chemical polishing is the purpose of surface polishing by chemical non-selective etching, and the wafer surface has few residual mechanical damage layers, but the surface state and the geometric dimension precision are poor. The mechanical polishing is to achieve the purpose of surface polishing by mechanical friction, the wafer surface which is as bright as a mirror can be easily obtained, the geometric dimension precision of the wafer is higher, but the depth of the residual mechanical damage layer is influenced by the polishing type and the granularity. Chemical mechanical polishing is the process of chemically reacting the wafer surface with the polishing material to produce water soluble compounds and then wiping off the chemical reactants by controlled mechanical friction to achieve the purpose of polishing. In this embodiment, the manner of polishing the wafer may be selected according to the actual application scenario.
In addition, when the surface of the wafer provided with the first groove and the second groove is the back surface of the wafer, the second surface is the front surface of the wafer, and in the step, the polished surface and the grooved surface of the wafer are oppositely arranged, so that the tensile stress generated by grooving the back surface of the wafer can reduce the deformation stress of the wafer, and the warping and bending caused by the stress difference between the polished surface and the unpolished surface of the wafer are inhibited.
According to the substrate processing method capable of reducing the deformation stress, after a wafer is ground, a first groove and a second groove which are transverse and longitudinal are formed in the first surface of the wafer through a grooving grinding wheel, so that the back of the wafer is divided into a plurality of areas through the first groove and the second groove. The method aims to reduce the stress difference between the polished surface of the wafer and the unpolished line more uniformly and better when the single-side polishing processing is carried out on the wafer, so that the surface tensile stress is reduced, the warping deterioration of the wafer in the back-end processing is avoided, and the flatness of a substrate finished product can be improved. On the other hand, since the tensile stress is released, the bending degree during the high-temperature operation of epitaxial epitaxy is lower than that of the substrate without groove (ordinary substrate), so that the groove is formed on the back surface of the wafer to make the wavelength uniformity of epitaxial epitaxy better.
In an embodiment of the present invention, the cross-sectional shapes of the first trench and the second trench are both trapezoidal, and at this time, the shape of each region on the first surface of the wafer, which is divided by the first trench and the second trench, is a frustum of a prism; and further, if the sizes of the first grooves and the second grooves are the same, and the distance between two adjacent first grooves is equal to the distance between two adjacent second grooves, the frustum-shaped area formed by the first grooves and the second grooves in a dividing mode is in a regular frustum shape. Correspondingly, the cross section shape of the grinding ring on the plane passing through the axis of the grooved grinding wheel and the cross section shapes of the first groove and the second groove are both trapezoidal. Referring to fig. 3, the grooved grinding wheel of fig. 3 has a plurality of abrasive rings 110 on the outer surface, and the adjacent abrasive rings 110 are equally spaced.
Further, the cross sectional shape of the abrasive ring on the grooved grinding wheel is isosceles trapezoid, the height of the abrasive ring protruding at the moment is 50 +/-20 um, the top width size range of the isosceles trapezoid of the cross sectional shape of the abrasive ring is 500 +/-20 um, the bottom width size range is 1000um +/-20 um, and the interval range between two adjacent abrasive rings is 2300um +/-20 um. It is easy to understand that, the size of the first groove and the second groove formed on the back surface of the wafer based on the grooving grinding wheel is consistent with the shape and size of the grinding ring on the grooving grinding wheel, that is, the cross-sectional shapes of the first groove and/or the second groove are both trapezoidal, the width size range of the top of the trapezoid is 500 +/-20 um, the width size range of the bottom of the trapezoid is 1000um +/-20 um, the height range of the trapezoid is 50 +/-20 um, and the distance between any two first grooves or any two second grooves is 2300um +/-20 um. Illustratively, the protruding height of abrasive ring is 50um, and the top width dimension of abrasive ring cross-section is 500um, and the bottom width dimension is 1000um, and the interval between the slot is 2300um. It should be understood that the number of abrasive rings on a grooved grinding wheel is not particularly limited, but that a greater number of rings will result in a corresponding higher grooving efficiency; and the size and the interval size of the abrasive rings on the grooved grinding wheel can be specifically limited according to application scenes.
In one embodiment, the substrate of the grooved grinding wheel is stainless steel, and each grinding ring of the grooved grinding wheel is plated with nickel layer, and a plurality of diamond particles are attached to the surface of the grinding ring. Referring to fig. 7, when the surface of the wafer is grooved, the abrasive ring of the grooving wheel is perpendicular to the wafer to ensure that the surface cutting angle and depth are as expected. For example, the diamond grains of the grooved grinding wheel can be 500 to 600, and 500 is selected optionally; the grooved grinding wheel rotates at a first rotating speed, the first rotating speed range is 2000 rpm-2500 rpm, and the optimal surface grinding rotating speed is 2200rpm; the grinding time per unit area is in the range of 5 to 10 seconds, and the optimum grinding time is 8 seconds. In the embodiment, the size of the diamond particles on the grooving grinding wheel is 500 # so as to better perform grooving; because when the diamond particles are small, it is difficult to achieve the desired grinding effect, and when the diamond particles are large, the diamond particles on the grooved wheel are easily detached. In addition, when the first rotating speed of the grooving grinding wheel is too high, an air inflation effect is generated, so that the cutting fluid cannot flow to a grinding surface well; when the first rotation speed of the grooving grinding wheel is too low, the surface of the grinding surface is more brittle, and the grooving efficiency is low, so that when the grooving grinding wheel is used for grooving the back surface of a wafer, the rotation speed of the grooving grinding wheel is 2000rpm to 2500rpm, the condition can be effectively avoided, and preferably, the rotation speed of the grooving grinding wheel is 2200rpm.
Fig. 7 is a schematic diagram of a grooving apparatus for grooving a substrate according to an embodiment of the present invention, and as shown in fig. 7, the grooving apparatus mainly includes a stage and a vacuum base, and a grooving wheel of the grooving apparatus rotates at a speed of R1, and the grooving wheel is perpendicular to and in contact with a wafer surface. During the rotation process of the grooved grinding wheel, the carrying platform is kept still; when the direction or position of the wafer needs to be changed, the carrier can rotate at the speed of R2 and can move along the X2 and Y directions. In addition, the grooved grinding wheel can also move along the horizontal direction X1 and the height direction Z, and the grooved grinding wheel moves along the height direction Z so as to enable the abrasive ring of the grooved grinding wheel to be in contact with the surface of the wafer. The vacuum pedestal is the pedestal for sucking the wafer, and the vacuum pressure is in the range of about minus 60-80 kpa, preferably minus 70kpa.
Correspondingly, the invention also discloses a substrate capable of reducing the deformation stress, and the substrate is processed by adopting the substrate processing method capable of reducing the deformation stress in any embodiment. Fig. 4 is a schematic structural diagram of a substrate capable of reducing a deformation stress according to an embodiment of the present invention, as shown in fig. 4, a plurality of first trenches and a plurality of second trenches on a first surface of the substrate have the same size and shape, and a distance between any two first trenches on the substrate is equal to a distance between any two second trenches on the substrate, at this time, each region on a back surface of the wafer of fig. 4 has a regular frustum shape; as can be seen from fig. 4, the grooved finished wafer surface has regular grooves, and a plurality of grooves are completely distributed on the wafer surface, so that the tensile stress on the wafer surface is released, and the residual stress and the substrate deformation of the wafer are limited to the minimum during the subsequent copper polishing and polishing process. In this embodiment, the number of the first grooves on the first surface is 33, and the number of the second grooves is 34; it will be understood that the number of first grooves and the number of second grooves are related to the size of the grinding ring and the size of the wafer, so that the number and size and shape of the grooves on the wafer can be changed according to actual needs when the substrate is specifically processed.
FIG. 5 is a schematic view of a portion of the structure of the substrate shown in FIG. 4, and FIG. 6 is a partial SEM image of the substrate shown in FIG. 5; as can be seen in fig. 6, the surface grooves were intact after the surface of the wafer was grooved without chipping or other damage to the wafer.
For better illustration of the present invention, the technical effects of the present invention will be illustrated below by comparing the degree of bending and deformation of the substrate of the prior art and the substrate of the present invention during the respective processes. Exemplarily, take the cross-sectional shape of the trench as a trapezoid, the width of the top of the trapezoid is 500um, the width of the bottom of the trapezoid is 1000um, the height of the trapezoid is 50um, and the distance between two adjacent trenches is 2300um. FIGS. 8a to 8d are graphs comparing the degree of bending and deformation of the prior art substrate (control) not grooved on its surface and the substrate of the present invention grooved on its back surface (experimental) during the respective processes; FIG. 8a is a simulation of the bending and deformation of the control group after annealing, and it can be seen from FIG. 8a that the Warp and Bow of the control group after annealing are 10.36um and-3.80 um, respectively; FIG. 8b is a simulation diagram of the degree of warpage and deformation of the control group after polishing, and it can be seen from FIG. 8b that the wafer type variation is large due to the uneven stress on both sides after copper polishing, the Warp is 88.90um, and the bow is 73.84um; FIG. 8c is a simulation diagram of the bending and deformation degrees of the experimental group after annealing, and it can be seen from FIG. 8c that Warp and Bow of the experimental group after annealing are 10.55um and-3.01 um, respectively; FIG. 8d is a simulation of the bending and deformation after polishing in the experimental group, and it can be seen from FIG. 8d that the Warp of the experimental group after surface copper polishing is 83.28um and the bow of the experimental group is 67.84um. As can be seen from fig. 8a to 8d, the grooved test group substrate of the present invention can effectively reduce the tensile stress caused by the uneven stress on both surfaces when the surface is diamond-ground, and further reduce the degree of wafer warpage.
In another embodiment, on the basis of the material sheet source with the same quality as the previous embodiment, the width of the bottom of each trapezoidal groove is 700 +/-20 um, the width of the top of each trapezoidal groove is 1000um +/-20 um, the distance between every two adjacent grooves is 2300 +/-20 um, and the depth of each groove is 70 +/-20 um; in this case, the wafer of this example has a Warp and a Bow of 10.47um and-3.39 um, respectively, after annealing, and a Warp of 84.28um and a Bow of 72.81um after surface copper polishing; the substrate of this embodiment has a defect that stress release is incomplete, the supporting surface of the top end of the wafer is reduced, and the probability of breakage is increased, compared with the substrate of the above embodiment. Thus, preferably, the cross-sectional dimension of the abrasive ring of the grooved grinding wheel selected can be defined as the protruding height of the abrasive ring being 50 ± 20um, and the cross-sectional shape of the abrasive ring has a top width dimension ranging from 500 ± 20um, a bottom width dimension ranging from 1000um ± 20um, and a spacing between two adjacent abrasive rings ranging from 2300um ± 20um.
Through the embodiment, the grooving grinding wheel performs transverse and longitudinal grooving on the back surface of the wafer, so that a plurality of uniform grids are formed in the effective use area of the back surface of the wafer, the grids are trapezoidal blocks, and the length, the width, the height, the side length and the like of each trapezoidal block are approximately equivalent; the grooving mode enables the surface roughness generated after the grinding process of the wafer to be divided by regional uniform division, so that the stress can be released as uniformly as possible during the later processing.
After the sapphire wafer is subjected to a grinding process, the thickness uniformity and flatness of the wafer are better than those of a cutting piece, so that the grooving depth and shape can be ensured to be consistent by using a trapezoidal grinding wheel; after the surface of the wafer is grooved, the internal residual stress of the substrate is further released through annealing, and the deformation quantity generated by the stress of the substrate is more uniform and flatter due to the factor of consistent grooving shape when the stress is released; therefore, the influence on the subsequent process is small, the warping deformation is lower, and the quality of the finished product of the wafer is improved. The wafer with the groove on the back surface can reduce the deformation stress of the wafer and inhibit the warping degree and bending degree formed by the stress difference between the polished surface and the unpolished surface of the wafer because the groove generates tensile stress.
It should also be noted that the exemplary embodiments noted in this patent describe some methods or systems based on a series of steps or devices. However, the present invention is not limited to the order of the above steps, that is, the steps may be performed in the order mentioned in the embodiments, may be performed in an order different from the order in the embodiments, or may be performed at the same time.
Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments in the present invention.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes may be made to the embodiment of the present invention by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A method of processing a substrate to reduce a deformation stress, the method comprising:
cutting a crystal bar into wafers, and grinding the wafers to improve the flatness of the wafers;
adsorbing a ground wafer on a vacuum seat on a carrying platform, forming a plurality of first grooves parallel to a first direction on a first surface of the wafer by using a grooving component, wherein the first direction is parallel to the flat edge direction of the wafer, the plurality of first grooves are arranged at intervals in a first radial direction of the wafer, and the plurality of first grooves are fully distributed on the first surface of the wafer along the first radial direction;
utilizing the grooving component to open a plurality of second grooves perpendicular to the first grooves on the first surface of the wafer, wherein the second grooves are arranged at intervals in a second radial direction of the wafer, and the second grooves are distributed on the first surface of the wafer along the second radial direction;
carrying out high-temperature annealing on the wafer provided with the first groove and the second groove;
and polishing a second surface of the wafer provided with the first groove and the second groove by using polishing equipment, wherein the second surface is the surface of the wafer opposite to the first surface.
2. The method for processing a substrate capable of reducing deformation stress according to claim 1, wherein the grooved component is a grooved grinding wheel, the grooved grinding wheel comprises a plurality of parallel and spaced abrasive rings, and each abrasive ring is sleeved on the outer peripheral surface of the grooved grinding wheel.
3. The method for processing a substrate capable of reducing deformation stress according to claim 2, wherein the cross-sectional shape of the abrasive ring in a plane passing through the axis of the grooved grinding wheel and the cross-sectional shapes of the first groove and the second groove are both trapezoidal.
4. A method as claimed in claim 3, wherein the top width of the trapezoid is in the range of 500 ± 20um, the bottom width of the trapezoid is in the range of 1000um ± 20um, the height of the trapezoid is in the range of 50 ± 20um, and the distance between two adjacent grinding rings of the grooved grinding wheel is in the range of 2300um ± 20um.
5. A method for processing a substrate capable of reducing a deformation stress according to claim 1,
utilizing a grooving component to open a plurality of first grooves parallel to a first direction on a first surface of the wafer, comprising:
rotating at a first rotating speed by using a slotting component and moving along a first direction so as to open a plurality of first grooves parallel to the first direction on the first surface of the wafer; and/or
Opening a plurality of second grooves perpendicular to the first grooves on the first surface of the wafer by using the grooving member, including:
and rotating the wafer by 90 degrees or 270 degrees, rotating the wafer at a first rotation speed by using a slotting component, and moving the wafer along a first direction to open a plurality of second grooves which are vertical to the first grooves on the first surface of the wafer.
6. A method for processing a substrate capable of reducing a deformation stress according to claim 5, wherein said first rotation speed is in a range of 2000rpm to 2500rpm, and the grinding time per unit area is in a range of 5 to 10 seconds.
7. The method for processing a substrate capable of reducing deformation stress according to any one of claims 2 to 6, wherein the abrasive ring is plated with nickel, and a plurality of diamond particles are attached to the surface of the abrasive ring.
8. The method for processing a substrate capable of reducing deformation stress according to claim 7, wherein the grinding of the wafer comprises:
and carrying out double-sided grinding on the wafer.
9. A substrate capable of reducing deformation stress, wherein the substrate is processed by the substrate processing method capable of reducing deformation stress according to any one of claims 1 to 8.
10. A substrate capable of reducing deformation stress according to claim 9, wherein the number of the first trenches on the substrate is 33, and the number of the second trenches on the substrate is 34.
CN202210977056.7A 2022-08-15 2022-08-15 Substrate processing method capable of reducing deformation stress and substrate Pending CN115332052A (en)

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