TWI834456B - Grinding wheels, grinding equipment and silicon wafers - Google Patents

Abstract

Embodiments of the present invention disclose a grinding wheel, grinding equipment and silicon wafers. The grinding wheel includes: a base with a central axis; distributed along a circumferential direction on a surface of the base perpendicular to the central axis and from the surface A plurality of protruding grinding teeth, the plurality of grinding teeth are arranged to be able to rotate together with the base around the central axis of the base to grind the surface of the silicon wafer in the target plane through the end of each grinding tooth ; Driving module, the driving module is configured to: when the central axis of the base is not perpendicular to the target plane, the driving module moves each grinding tooth along the central axis so that the end of each grinding tooth Always in this target plane.

Description

Grinding wheels, grinding equipment and silicon wafers

The present invention relates to the technical field of semiconductor manufacturing, and particularly belongs to grinding wheels, grinding equipment and silicon wafers.

The production technology of semiconductor silicon wafers usually includes processes such as crystal pulling, wire cutting, grinding, and polishing. Double-sided grinding is a grinding technology used to grind the two main surfaces of a silicon wafer simultaneously to make the silicon wafer have a highly flat surface. During the double-sided grinding process, a special device is required to hold the silicon wafer so that the grinding wheel can grind both main surfaces of the silicon wafer simultaneously. Usually, this holding device includes a pair of hydrostatic supports arranged oppositely, and the silicon chip is arranged between the two hydrostatic supports in the vertical direction. The hydrostatic support can be between itself and the silicon chip. A fluid barrier is formed between the main surfaces so that the silicon wafer can be held upright without contact with the two hydrostatic supports. At the same time, the two main surfaces of the silicon wafer can be polished using opposing grinding wheels. The surface is ground. Compared with physical clamping, the fluid clamping method of the hydrostatic support reduces damage to the silicon sheet and allows the silicon sheet to move (rotate) in the tangential direction relative to the surface of the hydrostatic support with less friction.

However, for the above-mentioned double-sided grinding technology, with the continuous operation of the equipment and the continuous supply of grinding water, the temperature of the grinding chamber will continue to change, resulting in a certain deformation of the bed body of the metal grinder. As the left and right grinding wheels pass through The support rod is fixed on the grinder. Once the grinder deforms, the contact position of the left and right grinding wheels relative to the silicon chip will change accordingly. That is to say, the grinding position changes. When the actual grinding position does not meet the expected requirements, Not only will it affect the grinding efficiency, but it may also reduce the flatness of the ground silicon wafers.

Therefore, during the double-sided grinding process, the position of the grinding teeth of the grinding wheel relative to the silicon wafer is adjusted immediately to ensure that the left and right grinding wheels continue to remain within the position range that can achieve better grinding effects, which is important for improving grinding efficiency and Very important for grinding effect.

In view of this, embodiments of the present invention are expected to provide a grinding wheel, a grinding equipment and a silicon wafer. By using the grinding wheel, the position of the grinding wheel, especially the grinding teeth of the grinding wheel, relative to the surface to be ground of the silicon wafer can be adjusted, so that even if the grinding The position of the wheel changes due to the deformation of the grinder, but the grinding teeth of the grinding wheel continue to remain within the position range that can achieve better grinding effects, thus ensuring grinding efficiency and grinding effect.

The technical solution of the present invention is implemented as follows: In a first aspect, an embodiment of the present invention provides a grinding wheel, which includes: a base with a central axis; A plurality of grinding teeth distributed in a circumferential direction on a surface of the base perpendicular to the central axis and protruding from the surface, the plurality of grinding teeth being arranged to be able to circle the center of the base together with the base The axis is rotated to grind the surface of the silicon wafer in the target plane through the end of each grinding tooth; The driving module is configured to: when the central axis of the base is not perpendicular to the target plane, the driving module moves each grinding tooth along the central axis so that the end of each grinding tooth always is in the target plane.

In a second aspect, embodiments of the present invention provide a grinding equipment for double-sided grinding of silicon wafers. The grinding equipment includes: Two static pressure supports disposed oppositely on both sides of the silicon chip, the two static pressure supports being used to support the silicon chip in a non-contact manner by providing hydrostatic pressure; Two grinding wheels according to the first aspect are disposed facing each other on both sides of the silicon chip.

In a third aspect, an embodiment of the present invention provides a silicon wafer obtained by using the grinding device according to the second aspect.

Embodiments of the present invention provide a grinding wheel, a grinding equipment and a silicon wafer; the grinding wheel includes a driving module, and the driving module is configured such that when the central axis of the base of the grinding wheel is not perpendicular to the target plane, the driving module Each grinding tooth is moved along the central axis, so that if the position of the grinding wheel is shifted or deflected due to the influence of associated components or other factors in the working environment, resulting in the grinding wheel, especially the grinding teeth of the grinding wheel, not reaching By presetting the grinding position, the driving module can be used to move each grinding tooth along the central axis, that is, the driving module can be used to adjust the length of each grinding tooth extending from the base, so that the end of each grinding tooth is always in the target plane. , that is, on the surface of the silicon wafer to be ground, the surface to be ground of the silicon wafer is always ground at the same time, thereby ensuring the grinding efficiency and grinding effect, so that the surface of the ground silicon wafer has better flatness.

In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, but are not used to limit the present invention.

It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

It should be understood that the terms "length", "width", "top", "bottom", "front", "back", "left", "right", "vertical", "horizontal", "top", The orientations or positional relationships indicated by "bottom", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply the device referred to. Or elements must have a specific orientation, be constructed and operate in a specific orientation and therefore are not to be construed as limitations on the invention.

In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, features defined as "first" and "second" may explicitly or implicitly include one or more of these features. In the description of the present invention, "plurality" means two or more than two, unless otherwise explicitly and specifically limited.

In the present invention, unless otherwise clearly stated and limited, the terms "installation", "connection", "connection", "fixing" and other terms should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection. , or integrated; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be an internal connection between two elements or an interaction between two elements. For those with ordinary knowledge in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

Referring to Figure 1, a related double-sided grinding device 1 for grinding silicon wafers S is shown. The double-sided grinding device 1 includes a first static pressure support 11 and a second static pressure support 12 arranged oppositely. As well as the first grinding wheel 13 and the second grinding wheel 14 arranged oppositely, the first static pressure support member 11 and the second static pressure support member 12 are provided for two of the silicon wafer S placed between them. Fluid pressure is applied simultaneously on the side to support the silicon wafer S in a non-contact manner. The first grinding wheel 13 and the second grinding wheel 14 simultaneously grind the silicon wafer S according to a predetermined grinding trajectory when the silicon wafer S is supported by the static pressure support. The two sides of S are ground. The double-sided grinding device 1 also includes: a first horizontal support rod 15, a second horizontal support rod 16, a first vertical support rod 17, a second vertical support rod 18, and a base 19, wherein, The first static pressure support 11 and the first grinding wheel 13 and the second static pressure support 12 and the second grinding wheel 14 are respectively connected via the first horizontal support rod 15 and the first vertical support rod 17 and the second horizontal support rod 16 and The second vertical support rod 18 is supported on the base 19 .

In order to stably support each component of the double-sided grinding device so that the double-sided grinding operation can be performed stably, the base 19 is usually made of metal, and during grinding, grinding water needs to be provided to the grinding wheel and the silicon wafer to reduce friction. Unnecessary damage to silicon wafers. However, with the continuous processing of the equipment and the continuous supply of grinding water, the temperature of the grinding chamber will continue to change, causing a certain deformation of the metal base 19. Since the grinding wheel and the static pressure support are supported on the base through the support rod, Deformation of the abutment will cause the grinding position of the grinding wheel to change, ultimately leading to a deterioration in the accuracy of processing silicon wafers. For example, referring to Figure 2, when the base 19 is affected by temperature and causes its upper surface to expand upward, the first horizontal support rod 15, the second horizontal support rod 16, and the first vertical support rod 17 provided on the base 19 , the second vertical support rods 18 are deflected relative to their respective initial vertical positions. The deflection of the support rods causes the first static pressure support member 11 and the first grinding wheel 13 and the second static pressure support member 12 and the second grinding wheel. 14 are also deflected relative to their respective initial positions, and are no longer even parallel to the side of the silicon wafer S to be ground. Similarly, see Figure 3, when the base 19 is affected by temperature, its upper surface moves downward. When shrinking, the support rod, the static pressure support, and the grinding wheel are deflected relative to their respective initial positions. The deflection of the grinding wheel will cause the actual grinding plane and the silicon wafer surface to be unable to coincide, but to form a certain angle relative to each other. Angle, when the angle exceeds a certain range, it will result in that at any moment, only a part of the grinding wheel can perform the grinding operation. As schematically shown in Figure 4, only a part of the grinding teeth of the grinding wheel can be in contact with the silicon wafer. Moreover, the grinding depth of this part of the grinding teeth relative to the silicon wafer is usually higher than the preset value. In this case, not only the grinding efficiency is significantly reduced, but the flatness of the ground silicon wafer will not meet the expected requirements.

In order to solve the above problems, referring to Figure 5, an embodiment of the present invention proposes a grinding wheel 100. The grinding wheel 100 includes: a base 101 with a central axis X; a plurality of grinding teeth 102, which are arranged along the circumferential direction. The direction is distributed on a surface of the base 101 that is perpendicular to the central axis On and protruding from the surface 103 of the base 101, where the surface 103 is perpendicular to the central axis X, the plurality of grinding teeth 102 are arranged to be able to rotate together with the base 101 around the central axis The surface S1 to be polished in the target plane A-A of the silicon wafer S is ground through the end of each grinding tooth; the driving module 104 is configured to: when the central axis X of the base 101 is not in line with the When the target plane A-A is vertical, the driving module 104 moves each grinding tooth 102 along the central axis X so that the end of each grinding tooth is always in the target plane A-A.

As shown in FIG. 5 , the grinding wheel 100 is deflected, for example, due to the influence of related components, so that the central axis The grinding efficiency and grinding effect are still ensured even if the grinding wheel 100 is deflected. Different from related grinding wheels including fixed grinding teeth, the grinding teeth 102 of the grinding wheel 100 provided by the embodiment of the present invention are retractably arranged on the grinding wheel 100. In the base 101, specifically, the grinding teeth 102 of the grinding wheel 100 are configured to move along the central axis In the state of the grinding wheel 100 shown in 5, the protruding length of the grinding teeth 102A to 102G relative to the surface 103 gradually increases, so that the ends of the grinding teeth 102A to 102G are in the target plane A-A. In practical applications, the target plane A-A may be, for example, a vertical plane to coincide with the surface to be polished S1 of the silicon wafer S that is kept vertical, so that the grinding teeth 102A to 102G can simultaneously grind the surface to be polished S1 of the silicon wafer S through their respective ends. Since the grinding wheel 100 will rotate around the central axis X during the grinding operation, the position of each grinding tooth 102 of the grinding wheel 100 relative to the central axis Each grinding tooth 102 moves along the central axis During the process, the driving module 104 continues to move the grinding teeth 102A to 102G along the central axis The angle is gradually reduced, so that the ends of the grinding teeth 102A to 102G are always in the target plane A-A, so that the surface S1 to be polished of the silicon wafer S is always ground simultaneously.

An embodiment of the present invention provides a grinding wheel 100; the grinding wheel 100 includes a driving module 104, and the driving module 104 is configured so that when the central axis The driving module 104 moves each grinding tooth 102 along the central axis In particular, if the grinding teeth of the grinding wheel have not reached the preset grinding position, for example, only the ends of some of the grinding teeth can contact the silicon wafer, the driving module 104 can be used to move each grinding tooth 102 along the central axis The group 104 adjusts the length of each grinding tooth 102 extending from the base 101 so that the end of each grinding tooth 102 is always in the target plane A-A, that is, on the surface S1 of the silicon wafer to be polished, so as to always simultaneously grind the silicon wafer. The grinding surface S1 is used for grinding to ensure grinding efficiency and effect, so that the surface of the ground silicon wafer has better flatness.

In order to more accurately drive the movement of the grinding gear 102 along the central axis When the silicon wafer S is being ground, the distance between the position of each grinding tooth 102 on the surface 103 of the base 101 relative to the target plane is detected in real time, and the driving module 104 is configured to drive each grinding tooth 102 according to the distance. The teeth 102 move along the central axis X so that the end of each grinding tooth 102 is always in the target plane A-A.

Specifically, referring to FIG. 7 , the grinding wheel 100 includes a plurality of distance detection units 105 . For simplicity, only the distance detection units 105A and 105B are shown in FIG. 7 . However, those skilled in the art should understand that Yes, the distance detection unit 105 may have a corresponding number to the grinding teeth 102 and may be disposed adjacent to each grinding tooth 102 on the surface 103 of the base 101 of the grinding wheel 100, for example, the distance detection unit 105A is adjacent to the grinding tooth 102A. is disposed on the surface 103 to instantly measure the distance D1 between the position of the grinding teeth 102A on the surface 103 of the base 101 and the target plane A-A. Similarly, the distance detection unit 105B is disposed on the surface 103 adjacent to the grinding teeth 102B to Instantly measure the distance D2 between the position of the grinding teeth 102B on the surface 103 of the base 101 and the target plane A-A. The driving module 104 can compare the distance measured in real time by each distance detection unit 105 with the initial distance, and then use, for example, a motor, The linkage mechanism etc. moves each grinding tooth along the central axis Those with ordinary knowledge in the art can understand that the driving module 104 can also drive the grinding teeth to move along the central axis X through other related technical means, which will not be described again here.

In order to achieve precise driving of each grinding tooth 102, referring to Figure 8, according to another preferred embodiment of the present invention, the driving module 104 includes a plurality of fluid pressure driving units 106, and the plurality of fluid pressure driving units 106 are configured to When the grinding wheel 100 is grinding the silicon wafer S, a force is applied to each grinding tooth 102 along the central axis, so that each grinding tooth 102 is always on the silicon wafer S to be ground in the target plane A-A. Surface S1 exerts a constant force.

In the embodiment shown in FIG. 8 , one hydraulic fluid drive unit is provided for each grinding tooth. For the sake of clarity, only the fluid pressure drive units 106A, 106B, 106C and 106D are shown. When the chip S performs a grinding operation, each fluid pressure driving unit provides a force along the central axis If X is not perpendicular to the target plane A-A or only some of the ends of the grinding teeth can contact the silicon wafer, each fluid pressure drive unit can separately adjust the force applied to its associated grinding teeth so that each grinding tooth 102 is along the central axis. X always applies a constant force to the surface S1 to be polished of the silicon wafer S, so that each grinding tooth can simultaneously grind the surface S1 to be polished of the silicon wafer S during the entire grinding operation and the applied grinding force is always consistent. , so that the polished silicon wafer has better flatness.

Regarding the specific implementation of the fluid pressure drive unit, preferably, referring to FIG. 8 , each fluid pressure drive unit 106 includes: a fluid pressure cylinder 107 for containing fluid, and a piston 108 capable of reciprocating movement within the fluid pressure cylinder 107 , a pressure sensor 109 and a controller 110, wherein the piston 108 is fixedly connected to the grinding teeth 102, the pressure sensor 109 is configured to sense the reaction force of the silicon chip S to the grinding teeth 102, and the controller 110 is configured to be able to control the piston 108 to reciprocate in the fluid pressure cylinder 107 according to the sensing result of the pressure sensor 109, so that each grinding tooth always exerts force on the surface of the silicon chip in the target plane. constant force.

As shown in Figure 8, the piston 108 is disposed in the fluid pressure cylinder 107 along the direction of the central axis The teeth 102 move in the direction of the central axis X. During the grinding operation, if the grinding wheel 100 is deflected and/or offset relative to the silicon wafer S such that the central axis , then the force of the silicon chip S acting on each grinding tooth 102 will change. This change in force can be transmitted from the grinding tooth 102 through the piston 108 to the fluid in the fluid pressure cylinder 107, and therefore can be sensed by the pressure sensor 109. , the pressure sensor 109 can send the sensing result to the controller 110, and the controller 110 can adjust the pressure in the fluid pressure cylinder 107 by injecting fluid into the fluid pressure cylinder 107 or discharging fluid from the fluid pressure cylinder 107 according to the sensing result. Fluid pressure, and changes in the fluid pressure in the fluid pressure cylinder 107 can cause the piston 108 to move in the fluid pressure cylinder 107, thereby driving the grinding teeth 102 to move along the central axis A constant force is exerted on the surface S1 of the sheet S to be ground, which is in the target plane A-A. During the entire grinding process, the pressure sensor 109 can instantly detect changes in the fluid pressure in the fluid pressure cylinder 107, and the controller 110 can also instantly control the movement of the grinding teeth 102 along the central axis The force exerted by each grinding tooth 102 on the surface S1 to be grinded of the silicon chip S can still be kept constant even under 100° rotation.

As an illustrative and non-limiting example of the present invention, the fluid pressure driving unit 106 may include a hydraulic driving unit or a pneumatic driving unit.

According to another preferred embodiment of the present invention, the fluid pressure driving unit 106 may include a fluid pressure source (not shown in the figure) connected to the fluid pressure driving unit for providing fluid pressure to the fluid pressure driving unit 106 .

As for the material of the grinding teeth 102, preferably, the grinding teeth are made of diamond and bonding agent. Further preferably, the bond is a ceramic bond or a resin bond. Grinding teeth using ceramic bond have the advantages of good thermal stability, good grip of abrasive grains, and long service life; grinding teeth using resin bond The teeth have the advantages of good self-sharpening, low grinding heat generation and a certain degree of elasticity, which is beneficial to improving the surface roughness of the silicon wafer.

An embodiment of the present invention also provides a grinding equipment 10, which is used for double-sided grinding of silicon wafers. The grinding equipment 10 includes: Two static pressure support members (ie, the first static pressure support member 11 and the second static pressure support member 12) are disposed oppositely on both sides of the silicon chip. The two static pressure support members are used to provide fluid static pressure to Support the silicon wafer S in a non-contact manner; Two grinding wheels 100 according to the present invention are disposed on both sides of the silicon chip S facing each other.

An embodiment of the present invention also provides a silicon wafer, which is obtained by using the grinding device 10 of the present invention.

It should be noted that the technical solutions recorded in the embodiments of the present invention can be combined arbitrarily as long as there is no conflict.

It will be apparent to those of ordinary skill in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. In this way, if these modifications and variations of the present invention fall within the scope of the patent application of the present invention and the scope of equivalent technologies, the present invention is also intended to include these modifications and variations.

1:Double-sided grinding device 10:Grinding equipment 100:Grinder wheel 101:Pedestal 102:Grinding gear 102A-102G: Grinding gear 103:Surface 104:Driver module 105:Detection unit 105A-105B: Detection unit 106: Fluid pressure drive unit 106A-106D: Fluid pressure drive unit 107:Fluid pressure cylinder 108:Piston 109: Pressure sensor 11: First static pressure support 110:Controller 12:Second static pressure support 13: First grinding wheel 14:Second grinding wheel 15:First horizontal support rod 16:Second horizontal support rod 17:First vertical support rod 18:Second vertical support rod 19:Abutment S: Silicon chip S1: Surface to be ground X: central axis D1, D2: distance

Figure 1 is a schematic diagram of related double-sided grinding equipment; Figure 2 is another schematic diagram of the related double-sided grinding equipment, which shows the state in which the double-sided grinding equipment is deformed due to the influence of temperature; Figure 3 is another schematic diagram of the related double-sided grinding equipment, which shows another state in which the double-sided grinding equipment is deformed due to the influence of temperature; Figure 4 is a schematic diagram of a related grinding wheel performing a grinding operation on a silicon wafer; Figure 5 is a schematic diagram of a grinding wheel provided by an embodiment of the present invention; Figure 6 is another schematic diagram of a grinding wheel provided by an embodiment of the present invention; Figure 7 is a schematic diagram of a grinding wheel provided by another embodiment of the present invention; Figure 8 is a schematic diagram of a grinding wheel provided by another embodiment of the present invention; Figure 9 is a schematic diagram of the grinding equipment provided by the embodiment of the present invention.

100:Grinder wheel

101:Pedestal

102:Grinding gear

102A-102G: Grinding gear

103:Surface

104:Driver module

S: Silicon chip

S1: Surface to be ground

X: central axis

Claims (8)

A grinding wheel, the grinding wheel includes: a base with a central axis; a plurality of grinding teeth distributed along a circumferential direction on a surface of the base perpendicular to the central axis and protruding from the surface, the plurality of grinding teeth The grinding teeth are configured to rotate together with the base around the central axis of the base to grind the surface of the silicon wafer in the target plane through the end of each grinding teeth; the driving module is configured to : When the central axis of the base is not perpendicular to the target plane, the driving module moves each grinding tooth along the central axis so that the end of each grinding tooth is always in the target plane; where, the The driving module includes a plurality of fluid pressure driving units configured to apply a force along the central axis to each grinding tooth when the grinding wheel grinds the silicon wafer, so that each grinding tooth A constant force is always applied to the surface of the silicon chip in the target plane; each fluid pressure drive unit includes: a fluid pressure cylinder for containing fluid, a piston capable of reciprocating movement in the fluid pressure cylinder, a pressure sensor A sensor and a controller, wherein the piston is fixedly connected to the grinding teeth, the pressure sensor is configured to sense the reaction force of the silicon chip on the grinding teeth, and the controller is configured to be able to adjust the pressure sensor according to the reaction force of the silicon chip on the grinding teeth. The sensing result controls the piston to reciprocate in the fluid pressure cylinder, so that each grinding tooth always exerts a constant force on the surface of the silicon chip in the target plane. The grinding wheel according to claim 1, wherein the grinding wheel further includes a plurality of distance detection units unit, the plurality of distance detection units are used to detect the distance between the position of each grinding tooth on the surface of the base relative to the target plane in real time when the grinding wheel is grinding the silicon wafer, and the driving module It is arranged to be able to drive each grinding tooth to move along the central axis according to the distance, so that the end of each grinding tooth is always in the target plane. The grinding wheel according to claim 1, wherein the fluid pressure driving unit further includes a fluid pressure source connected to the fluid pressure driving unit for providing fluid pressure to the fluid pressure driving unit. The grinding wheel according to any one of claims 1 or 3, wherein the fluid pressure driving unit includes a hydraulic driving unit or a pneumatic driving unit. The grinding wheel according to claim 1 or 2, wherein the grinding teeth are made of diamond and bonding agent. The grinding wheel according to claim 5, wherein the bond is a ceramic bond or a resin bond. A grinding equipment used for double-sided grinding of silicon wafers. The grinding equipment includes: two static pressure supports disposed oppositely on both sides of the silicon wafer. The two static pressure supports are used to provide The hydrostatic pressure supports the silicon chip in a non-contact manner; two grinding wheels as described in any one of claims 1 to 6 are arranged facing each other on both sides of the silicon chip. A silicon flake obtained by using the grinding equipment as described in claim 7.

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