CN101444898A - Grinding wheel mounting mechanism - Google Patents

Abstract

The invention provides a grinding wheel installation mechanism, which can install two kinds of grinding tools at the same time or separately according to the needs. , the grinding wheel includes: a first grinding wheel, which is composed of an annular first wheel base with an inner diameter of a first size, and a plurality of first grinding tools installed on the first wheel base; and a second grinding wheel, which Consisting of a second wheel base whose outer diameter is a second size smaller than the first size, and a plurality of second grinding tools installed on the second wheel base, the wheel base has: a ring-shaped first mounting surface , which is used to install the first wheel base of the first grinding wheel; and the second mounting surface, which is arranged on the inner peripheral portion of the first mounting surface, and is used to install the second wheel base of the second grinding wheel, between the first and When the second grinding wheel is installed on the first and second mounting surfaces respectively, the end surface of the second grinding tool of the second grinding wheel protrudes a predetermined distance from the end surface of the first grinding tool of the first grinding wheel.

Description

Grinding Wheel Mounting Mechanism

technical field

The invention relates to a grinding wheel installation mechanism in a grinding device.

Background technique

In the semiconductor device manufacturing process, a plurality of regions are divided on the surface of a substantially disk-shaped semiconductor wafer by dividing lines called streets arranged in a grid pattern, and IC (Integrated ICs) are formed in these divided regions. Circuit: integrated circuit), LSI (Large Scale Integration: large scale integrated circuit) and other devices. Next, by cutting the semiconductor wafer along the lanes with a cutting device, the semiconductor wafer is divided into individual semiconductor chips.

The divided wafer is formed into a predetermined thickness by grinding or etching the back surface before cutting along the lanes. In recent years, in order to achieve weight reduction and miniaturization of electrical equipment, the thickness of the wafer is required to be thinner, for example, about 50 μm.

Grinding equipment that thins the backside of a wafer has adopted various methods in order to finish a thin wafer with high bending strength in order to meet this requirement. become a very difficult problem.

Therefore, in order to realize wafer thinning and ease of handling, for example, in Japanese Patent Application Laid-Open No. 2007-19461, a grinding method has been proposed: only the parts where devices such as ICs and LSIs are formed on the wafer are ground, and The protrusions are left in the remaining area of the outer periphery.

Patent Document 1: Japanese Patent Laid-Open No. 2007-19461

However, with regard to the grinding wheel used in the above-mentioned processing method, compared with the grinding wheel used for grinding the entire surface of the wafer, the outer diameter of the wheel and the array diameter of the grinding wheels arranged in a ring shape are greatly different ( It is smaller in comparison), so it cannot be used with the usual grinding wheel, and the grinding wheel must be replaced.

In addition, there is a grinding method having a reinforcing part forming process in which only the central part of the wafer where devices such as ICs and LSIs are formed is ground, leaving the remaining area of the outer peripheral part. Convex. In the above-mentioned grinding method, it is necessary to grind only the convex portions to flatten the wafer to some extent immediately before final separation into individual devices.

In the grinding that only grinds the peripheral convex portion so that the wafer is flattened to a certain extent, a grinding device is also used, and since it is necessary to use a grinding tool of coarse grinding grains and a grinding tool of fine grinding grains for grinding Grinding, so two kinds of grinding wheels with two kinds of grinding tools are needed, and one needs to replace the grinding wheels to complete the desired grinding.

Contents of the invention

The present invention has been made in view of these problems, and an object of the present invention is to provide a grinding wheel mounting mechanism for a grinding device that can simultaneously or individually mount two types of grinding stones as needed.

According to the present invention, there is provided a grinding wheel mounting mechanism, which mounts the grinding wheel on a wheel base fixed to the main shaft of the grinding device in a detachable manner, and is characterized in that,

The grinding wheels mentioned above include:

a first grinding wheel consisting of an annular first wheel base and a plurality of first grinding tools mounted on the first wheel base, the inner diameter of the first wheel base being a first size; and

The second grinding wheel is composed of a second wheel base and a plurality of second grinding tools installed on the second wheel base. The outer diameter of the second wheel base is a second size smaller than the first size. size,

The above-mentioned wheel seat has: a ring-shaped first mounting surface, which is used to mount the first wheel base of the first grinding wheel; and a second mounting surface, which is arranged the second wheel base of said second grinding wheel,

When the above-mentioned first grinding wheel and the above-mentioned second grinding wheel are installed on the above-mentioned first mounting surface and the above-mentioned second mounting surface respectively, the end surface of the above-mentioned second grinding tool of the above-mentioned second grinding wheel The end face of the grinding tool protrudes a predetermined distance.

Preferably, the grinding wheel installation mechanism includes a grinding fluid nozzle, the grinding fluid nozzle is installed in the central part of the above-mentioned wheel seat, and is used to spray grinding fluid, and the protruding height of the grinding fluid nozzle is higher than that of the first grinding fluid. The protruding height of the grinding tool and the second grinding tool should be low.

Furthermore, it is preferable that either one of the first grinding wheel and the second grinding wheel can be attached and detached without interfering with the other in a state where the first grinding wheel and the second grinding wheel are attached to the wheel base.

According to the present invention, since the wheel seat has a first mounting surface and a second mounting surface, the first grinding wheel with a common outer diameter and the second grinding wheel with a smaller outer diameter can be installed on the wheel seat at the same time, or only one of them can be installed as required One grinding wheel, so it is possible to use one spindle to perform all the following grinding: grinding of the entire surface of the workpiece, grinding of the reinforcement part forming process that leaves convex parts in the remaining area of the outer peripheral part of the workpiece, and grinding of convex parts only.

In addition, the first grinding wheel and the second grinding wheel can be freely mounted on the wheel base, and if the grinding wheel of one of the grinding wheels is damaged or worn, only the grinding wheel can be replaced, which is very economical. In addition, compared with a grinding device having two or more spindles, it is advantageous in terms of economy and space to provide a grinding device with a small space at a greatly reduced price.

Description of drawings

FIG. 1 is a front perspective view of a semiconductor wafer.

Fig. 2 is a rear perspective view of the semiconductor wafer to which the protective tape is attached.

Fig. 3 is an external perspective view of a grinding device suitable for applying the grinding wheel installation mechanism of the present invention.

Fig. 4 is a perspective view of the chuck table unit and the chuck table feeding mechanism.

(A) of FIG. 5 is a perspective view showing a state in which a first grinding wheel is attached to a wheel base, and FIG. 5(B) is a perspective view showing a state in which a second grinding wheel is attached to a wheel base.

(A) of FIG. 6 is a cross-sectional view of a state in which a first grinding wheel is attached to a wheel base, and FIG. 6(B) is a cross-sectional view of a state in which a second grinding wheel is attached to a wheel base.

Fig. 7 is a perspective view showing a state in which first and second grinding wheels are mounted on the wheel base.

Fig. 8 is a cross-sectional view of a state where first and second grinding wheels are mounted on the wheel base.

(A) of FIG. 9 is an explanatory diagram showing the situation where the entire back surface of the wafer is ground by the first grinding wheel, and (B) of FIG. 9 is grinding only the back surface corresponding to the device region of the wafer by the second grinding wheel. , and an explanatory diagram of a grinding method that leaves a ring-shaped convex portion in the remaining area of the outer periphery.

(A) of FIG. 10 is an explanatory diagram of a grinding process in which only the back surface corresponding to the device region of the wafer is ground using the second grinding wheel, and a ring-shaped convex portion is left in the remaining area of the outer periphery, and (B) of FIG. 10 It is an explanatory diagram showing the process of roughly grinding the annular convex portion with the second grinding wheel, and (C) of FIG. 10 is an explanatory diagram showing the process of finishing grinding the annular convex portion with the first grinding wheel.

Fig. 11 is an explanatory diagram of a concave portion grinding step performed by a second grinding machine.

12 is an enlarged cross-sectional view of a semiconductor wafer subjected to a recess grinding step.

Label description

2: grinding device; 11: semiconductor wafer; 16: grinding member (grinding unit); 24: spindle; 28: wheel base; 28a: first mounting surface; 28b: second mounting surface; 30: first grinding wheel ; 34: first grinding tool; 38: second grinding wheel; 42: second grinding tool; 92: grinding fluid nozzle.

Detailed ways

Hereinafter, a grinding wheel mounting mechanism according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of a semiconductor wafer before processing to a predetermined thickness. The semiconductor wafer 11 shown in FIG. 1 is made of, for example, a silicon wafer with a thickness of 700 μm. On the surface 11 a, a plurality of spaced roads 13 are formed in a grid pattern. Devices 15 such as ICs and LSIs are formed in the region.

The semiconductor wafer 11 thus constituted has a device region 17 in which the device 15 is formed, and a peripheral remaining region 19 surrounding the device region 17 . Further, on the outer periphery of the semiconductor wafer 11, a notch 21 is formed as a mark indicating the crystal orientation of the silicon wafer.

On the surface 11a of the semiconductor wafer 11, the protective tape 23 is pasted by the protective tape pasting process. Accordingly, the front surface 11a of the semiconductor wafer 11 is protected by the protective tape 23, and the rear surface 11b is exposed as shown in FIG. 2 .

Next, a grinding apparatus 2 for grinding the back surface 11b of the semiconductor wafer 11 thus configured to a predetermined thickness will be described with reference to FIG. 3 . The housing 4 of the grinding device 2 is composed of a horizontal housing part 6 and a vertical housing part 8 .

A pair of guide rails 12 , 14 extending in the vertical direction are fixed to the vertical housing portion 8 . A grinding member (grinding unit) 16 is attached so as to be movable in the up and down direction along the pair of guide rails 12 , 14 . The grinding unit 16 is mounted via a support portion 20 on a moving base 18 that moves in the vertical direction along a pair of guide rails 12 , 14 .

The grinding unit 16 includes: a spindle housing 22 mounted on the support portion 20 ; a spindle 24 rotatably accommodated in the spindle housing 22 ; and a servo motor 26 that drives the spindle 24 to rotate. The grinding liquid is supplied to the grinding member (grinding unit) 16 through the pipe 36 . Preferably, pure water is used as the grinding fluid.

The grinding device 2 has a grinding unit feed mechanism 44 that moves the grinding unit 16 in the vertical direction along the pair of guide rails 12 , 14 . The grinding unit feed mechanism 44 is composed of a ball screw 46 and a pulse motor 48 fixed to one end of the ball screw 46 . When the pulse motor 48 is pulse-driven, the ball screw 46 rotates, and the moving base 18 moves in the vertical direction via the nut of the ball screw 46 fixed inside the moving base 18 .

In the recess 10 of the horizontal housing part 6 a chuck table unit 50 is arranged. As shown in FIG. 4 , the chuck table unit 50 includes: a support base 52 ; and a chuck table 54 rotatably disposed on the support base 52 . The chuck table unit 50 further includes a cover body 56 having a hole through which the chuck table 54 is inserted.

The chuck table unit 50 is moved in the front-back direction of the grinding apparatus 2 by the chuck table moving mechanism 58 . The chuck table moving mechanism 58 is composed of a ball screw 60 and a pulse motor 64 connected to one end of a screw shaft 62 of the ball screw 60 .

When the pulse motor 64 is pulse-driven, the screw shaft 62 of the ball screw 60 rotates, and the support base 52 having a nut screwed with the screw shaft 62 moves in the front-rear direction of the grinding device 2 . Thereby, the chuck table 54 also moves in the front-rear direction corresponding to the rotation direction of the pulse motor 64 .

As shown in FIG. 3 , the pair of guide rails 66 , 68 and the chuck table moving mechanism 58 shown in FIG. 4 are covered by bellows 70 , 72 . That is, the front end of the bellows 70 is fixed to the front wall defining the recess 10 , and the rear end of the bellows 70 is fixed to the front end of the cover 56 . Furthermore, the rear end of the bellows 72 is fixed to the vertical housing portion 8 and the front end thereof is fixed to the rear end surface of the cover body 56 .

On the horizontal casing portion 6 of the casing 4, a first wafer cassette 74, a second wafer cassette 76, a wafer transfer member 78, a wafer temporary placement member 80, a wafer transfer-in member 82, a wafer transfer-out member 84 and cleaning Member 86. In addition, an operation member 88 for an operator to input grinding conditions and the like is provided in front of the housing 4 .

In addition, a cleaning liquid spray nozzle 90 for cleaning the chuck table 54 is provided substantially in the center of the horizontal housing portion 6 . The cleaning liquid spray nozzle 90 sprays the cleaning liquid onto the ground wafer held on the chuck table 54 with the chuck table 54 positioned in the wafer loading/unloading area.

By pulse-driving the pulse motor 64 of the chuck table moving mechanism 58, the chuck table unit 50 moves between the grinding area on the back side of the apparatus shown in FIG. 3 and the wafer loading and unloading area on the near side, In the above wafer loading and unloading area, wafers are received from the wafer loading and unloading means 82 and transferred to the wafer loading and unloading means 84 .

Next, the grinding wheel mounting mechanism according to the embodiment of the present invention will be described in detail with reference to FIGS. 5 to 8 . As shown in (A) of FIG. 5 and (A) of FIG. 6 , the wheel base 28 is screwed to the front end of the main shaft 24 by a plurality of screws 25 .

An annular first mounting surface 28 a is formed on the outermost peripheral portion of the wheel base 28 , and a second mounting surface 28 b recessed from the first mounting surface 28 a is formed on the inner peripheral portion of the wheel base 28 . A plurality of holes 27 are formed in the first mounting surface 28a, and a plurality of screw holes 29 are formed in the second mounting surface 28b.

30 is a first grinding wheel having a first inner diameter, which is formed by fastening a plurality of grinding tools 34 on the lower surface of an annular wheel base 32, and these grinding tools 34 are made of vitrified bond or the like. It is formed by fixing diamond abrasive grains.

As shown in (A) of FIG. 6 , the first grinding wheel 30 is mounted on the first mounting surface 28 a of the wheel base 28 by screwing a plurality of screws 33 into the threaded holes of the first grinding wheel 30 through the holes 27 .

The second grinding wheel 38 shown in (B) of FIG. 5 has an outer diameter of a second size smaller than the first size. Moreover, these grinding tools 42 are formed by fixing diamond abrasive grains with a vitrified bond or the like.

The wheel base 40 of the second grinding wheel 38 has a central hole 41 and a plurality of holes 31 for insertion of fixing screws. As shown in (B) of FIG. 5 and (B) of FIG. 6 , the second grinding wheel 38 is mounted to the second mounting position of the wheel base 28 by screwing the screw 35 through the hole 31 into the threaded hole 29 of the wheel base 28 . Surface 28b.

The grinding fluid nozzle 92 is fixed on the second mounting surface 28 b of the wheel seat 28 by a plurality of screws 37 . The outer diameter of the grinding fluid nozzle 92 is set to be smaller than the diameter of the central hole 41 of the second grinding wheel 38, and when the grinding fluid nozzle 92 is installed on the wheel base 28, the second grinding wheel 38 can be positioned relative to the wheel base 28. loading and unloading.

As shown in FIGS. 7 and 8 , with the first grinding wheel 30 mounted on the first mounting surface 28 a of the wheel base 28 , the second grinding wheel 38 can be mounted on the second mounting surface 28 b of the wheel base 28 .

Conversely, in a state where the second grinding wheel 38 is mounted on the second mounting surface 28b of the wheel base 28 , the first grinding wheel 30 can be mounted on the first mounting surface 28a of the wheel base 28 . That is, both the first grinding wheel 30 and the second grinding wheel 38 can be attached to and detached from the wheel base 28 without interference from the other.

As best shown in FIG. 8 , the grinding fluid nozzle 92 is fixed at the center of the wheel base 28 so as to protrude shorter than the grinding tool 34 of the first grinding wheel 30 and the grinding tool 42 of the second grinding wheel 38 . The grinding fluid nozzle 92 jets the grinding fluid from at least four directions toward the grinding tools 34 and 42 located in the outer peripheral direction.

Hereinafter, the grinding operation of the grinding apparatus 2 configured in this way will be described. The wafer stored in the first wafer cassette 74 is a semiconductor wafer with a protective tape attached to the front side (the surface on which the circuit is formed). Therefore, the wafer is stored in the first wafer cassette 74 with the back side on the upper side. The first wafer cassette 74 storing a plurality of semiconductor wafers in this way is placed on a predetermined cassette loading area of the casing 4 .

Then, when all the semiconductor wafers before grinding are loaded in the first wafer cassette 74 placed in the cassette loading area, the wafer cassette 74 that has become empty is manually moved out of the wafer cassette 74 containing a plurality of semiconductor wafers. A new first wafer cassette 74 is placed in the cassette loading area.

On the other hand, after a predetermined number of ground semiconductor wafers are loaded into the second wafer cassette 76 placed on a predetermined cassette unloading area of the housing 4, the second wafer cassette 76 is manually For unloading, a new empty second wafer cassette 76 is placed in the cassette unloading area.

The semiconductor wafers accommodated in the first wafer cassette 74 are transported by the vertical movement and forward and backward movement of the wafer transport member 78 and placed on the temporary wafer placement member 80 . After the wafer placed on the temporary wafer loading member 80 is centered here, the wafer carrying-in member 82 is rotated to perform the chucking operation of the chuck table unit 50 located in the wafer loading and unloading area. on the stage 54, and is sucked and held by the chuck table 54.

After the wafer is sucked and held by the chuck table 54 in this way, the chuck table moving mechanism 58 is operated to move and position the chuck table unit 50 in the grinding area at the rear of the apparatus.

When the chuck table unit 50 is positioned in the grinding area, the center of the wafer held on the chuck table 54 is positioned slightly beyond the outer circumference of the grinding wheel 30 as shown in FIG. 9(A).

Then, the chuck table 54 is rotated at a speed of, for example, about 100 to 300 rpm (revolutions per minute), the servo motor 26 is driven to rotate the grinding wheel 30 at a speed of 4000 to 7000 rpm, and the grinding unit is driven forward to perform The pulse motor 48 of the mechanism 44 lowers the grinding unit 16 .

Then, the grinding stone 34 of the grinding wheel 30 is pressed against the back surface (surface to be ground) of the wafer 11 on the chuck table 54 with a predetermined load, whereby the back surface of the wafer 11 is ground. By performing grinding for a predetermined time in this way, the wafer 11 is ground to a predetermined thickness.

After the grinding is completed, the chuck table moving mechanism 58 is driven to position the chuck table 54 in the wafer loading and unloading area on the front side of the apparatus. After the chuck table 54 is positioned in the wafer loading and unloading area, cleaning liquid is sprayed from the cleaning liquid spray nozzle 90 to clean the ground surface (back surface) of the wafer 11 held on the chuck table 54 after grinding. .

Next, in the case of a grinding method in which only the back surface of the device region 17 of the wafer 11 is ground and the convex portion is left in the remaining peripheral region 19, as shown in (B) of FIG. 9 , the second grinding wheel 38 Mounted on the wheel base 28 and then the grinding of the wafer 11 is carried out.

That is, in the case of this grinding method, as shown in FIG. 11 , the rotation center P1 of the chuck table 54 and the rotation center P2 of the grinding wheel 42 are eccentric, and the outer diameter of the grinding wheel 42 is set to Such size: less than the diameter of the boundary line 94 between the device region 17 and the peripheral remaining area 19 of the wafer 11, and greater than the radius of the boundary line 94, so that the annular grinding tool 42 passes through the center of rotation P1 of the chuck table 54 .

While the chuck table 54 is rotated at a speed of 300 rpm in the direction shown by the arrow 55, the grinding tool 42 is rotated at a speed of 6000 rpm in the direction shown by the arrow 96, and the servo motor 26 is operated to make the second The grinding stone 42 of the grinding wheel 38 is in contact with the back surface of the wafer 11 . Then, the second grinding wheel 38 is ground downward by a predetermined amount at a predetermined grinding feed speed.

As a result, as shown in FIG. 12 , on the back surface of the semiconductor wafer 11 , the region corresponding to the device region 17 is removed by grinding to form a circular concave portion 98 with a predetermined thickness (for example, 50 μm), and is connected to the remaining region 19 of the outer periphery. The corresponding area is left to form the annular protrusion (annular reinforcement) 100 .

Next, with reference to (A) to (C) of FIG. 10 , the following grinding method is described: the first and second grinding wheels 30, 38 are installed on the wheel holder 28, and only the wafer 11 and the device region 17 The corresponding backside is ground, leaving a ring-shaped protrusion in the peripheral residual region 19, and then only this ring-shaped protrusion is ground, so that the wafer is somewhat flattened.

In this case, for example, the grinding wheel 42 for rough grinding is attached to the second grinding wheel 38 , and the grinding wheel 34 for finishing grinding is attached to the first grinding wheel 30 . First, as shown in (A) of FIG. However, a peripheral residual region 19 of the wafer 11 remains.

Next, as shown in (B) of FIG. 10 , a rough grinding process of the annular reinforcement portion 39 is implemented using the second grinding wheel 38 , and then as shown in (C) of FIG. 10 , the annular convex portion is implemented using the first grinding wheel 30 . 39 fine grinding process.

In this way, according to the grinding wheel mounting mechanism of this embodiment, the first and second grinding wheels 30, 38 can be mounted on one spindle 24 to implement a cutting method in which an annular protrusion is formed in the remaining area 19 of the outer periphery of the wafer 11, and then Grinding the annular protrusion flattens the entire wafer 11 to some extent.

Claims (3)

1. A grinding wheel installation mechanism, which installs the grinding wheel on a wheel seat fixed to the main shaft of the grinding device in a freely removable manner, characterized in that, The grinding wheels mentioned above include: a first grinding wheel consisting of an annular first wheel base and a plurality of first grinding tools mounted on the first wheel base, the inner diameter of the first wheel base being a first size; and The second grinding wheel is composed of a second wheel base and a plurality of second grinding tools installed on the second wheel base. The outer diameter of the second wheel base is a second size smaller than the first size. size, The above-mentioned wheel seat has: a ring-shaped first mounting surface, which is used to mount the first wheel base of the first grinding wheel; and a second mounting surface, which is arranged the second wheel base of said second grinding wheel, When the above-mentioned first grinding wheel and the above-mentioned second grinding wheel are installed on the above-mentioned first mounting surface and the above-mentioned second mounting surface respectively, the end surface of the above-mentioned second grinding tool of the above-mentioned second grinding wheel The end face of the grinding tool protrudes a predetermined distance. 2. The grinding wheel mounting mechanism according to claim 1, wherein: The above-mentioned grinding wheel installation mechanism includes a grinding fluid nozzle, which is installed in the central part of the above-mentioned wheel base for spraying grinding fluid, The protruding height of the grinding fluid nozzle is lower than the protruding heights of the first grinding tool and the second grinding tool. 3. The grinding wheel installation mechanism as claimed in claim 1 or 2, characterized in that, In the state where the first grinding wheel and the second grinding wheel are attached to the wheel base, either one of the first grinding wheel and the second grinding wheel can be attached and detached.

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