JPH10156681A - Double surface grinding device for thin disk-shaped work piece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device capable of simultaneously and easily grinding both surfaces of a thin disk-shaped work piece and capable of being downsized. SOLUTION: A double surface grinding device is provided with a pair of grinding wheels 8, 9, and a work piece rotating device for supporting and rotating a work piece W so that the machining surfaces (b) of both surfaces of the work piece W may face the circular grinding surfaces of the grinding wheels 8, 9 and a part of the outer periphery of the work piece W and the center (c) may be positioned inside the outer peripheries of the grinding wheels. The work piece rotating device is, provided with a pair of position holding belts 21, 22 for pinching a part of the work piece W projecting from between the grinding wheels 8, 9 from both sides in the radial direction and for moving it in the circumferential direction of the work piece W, grooves 23 for supporting the work piece W in the axial and radial directions by fitting the outer periphery of the work piece W are provided on respective belts 21, 22, and at least one of the belts 21, 22 is a driving belt for rotating the work piece W by being rotated in the circumferential direction of the work piece W.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for grinding both sides of a thin disk-shaped work, and more particularly to an apparatus for simultaneously grinding both sides of a thin disk-shaped work such as a semiconductor wafer.

[0002]

2. Description of the Related Art As an apparatus for simultaneously grinding both surfaces of a work, a pair of rotating grinding wheels, which are arranged so that the grinding surfaces of the end surfaces face each other, are placed in a rotating disk-shaped carrier pocket. What passes through the work which has been used is conventionally known. In this case, the outer diameter (diameter) of the grinding surface of the grinding wheel
Must be larger than the outer diameter of the workpiece. Also,
In the carrier, a plurality of pockets are usually formed at equal intervals on a circumference close to the outer periphery, and a part of the carrier also enters between the pair of grinding wheels together with the wafer. The thickness must, of course, be smaller than the distance between a pair of grinding wheels during grinding, ie, the finished thickness of the work.

Incidentally, currently used semiconductor wafers have an outer diameter of about 200 mm (8 inches) and about 3 mm.
There is one with a thickness of 00 mm (12 inches), but the thickness (finished dimensions) is about 0.8 mm, and the thickness is extremely thin as compared with the outer diameter. When such a wafer is ground by the above-described apparatus, the outer diameter of the wafer is relatively large, so that the outer diameter of the grindstone increases, and the carrier that accommodates and rotates the wafer also increases. For this reason, the device becomes large. Further, since the thickness of the wafer is small, it is necessary to make the portion of the carrier between the grinding wheel and the wafer extremely thin. Grinding force acts on the part of the carrier, especially the pocket, that enters between the grinding wheels through the work contained in it, but when this part is made thinner, the strength decreases and the work can be moved smoothly. It becomes difficult. For this reason, it was conventionally difficult to grind both sides of the wafer.

[0004] A similar problem also occurs in the case of a thin disk-shaped work other than a wafer.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus which can simultaneously and easily grind both surfaces of a thin disk-shaped work and can reduce the size.

[0006]

SUMMARY OF THE INVENTION An apparatus according to the present invention comprises a pair of grinding wheels which are arranged and rotated so that circular grinding surfaces on end faces thereof are opposed to each other and relatively movable in an axial direction. Grinding stone and the processing surfaces on both surfaces of the thin disk-shaped work are respectively opposed to the grinding surfaces of the pair of grinding whetstones, and a part and the center of the outer periphery of the work are located inside the outer periphery of the grinding surface. Work rotation means for supporting the work between the grinding surfaces and rotating the work, wherein the work rotation means radially moves the portion of the work that is outside from between the grinding wheels. A pair of position holding belts sandwiched from both sides and arranged so as to be movable in the circumferential direction of the work are provided. The outer peripheral portion of the work is fitted to these belts, and the work is axially and radially mounted. Grooves for lifting is provided, at least one of said belt is characterized in that a drive belt for rotating the workpiece by being driven in the circumferential direction of the workpiece.

The work is supported and rotated by the work rotating means so that a part of the outer periphery and the center of the work are located inside the outer periphery of the grinding surface, and the work is rotated by a pair of grinding wheels. The workpiece is rotated while being in contact with each processing surface. By rotating the grinding wheel,
The work surface of the workpiece that is in contact with the ground surface is ground, and the workpiece rotates by itself while a part of the outer periphery and the center are positioned inside the outer periphery of the ground surface.
During rotation, the entire work surface of the workpiece passes between the grinding surfaces and comes into contact with the grinding surface. For this reason, it is possible to simultaneously grind the entire surface of both surfaces by simply rotating the work on the spot using a grinding wheel whose outer diameter is slightly larger than the radius of the work. It is only necessary to rotate the work on the spot, and it is not necessary to move it using a carrier as in the past.Thus, even a thin disk-shaped work can be easily and reliably ground, and the size of the device is small. Is possible. In addition, the entire processing surface of the work can be ground using a grinding wheel whose outer diameter of the grinding surface is slightly larger than the radius of the work, and it is necessary to use a large grinding wheel whose outer diameter of the grinding surface is larger than the outer diameter of the work. Because there is no, from this point,
The size of the device can be reduced.

Moreover, the work can be reliably supported in the axial direction and the radial direction and rotated by only a pair of position holding belts provided with grooves, so that the structure of the apparatus is simple and further downsizing is possible. It is. There are semiconductor wafers in which one portion of the outer periphery is cut out in an arc shape to form a flattening portion for positioning, and those in which this is not formed. The outer peripheral portion of the wafer is supported only by a belt. So
Not only a wafer without a positioning flat portion but also a wafer on which the flat portion is formed, the outer peripheral portion thereof can be reliably supported and rotated.

Therefore, according to the apparatus of the present invention, both sides of a thin disk-shaped workpiece can be simultaneously and easily ground with reliability, and the apparatus can be downsized.

For example, the pair of position holding belts
The work is attached to a pair of openable and closable members, and the outer peripheral portions on both sides in the radial direction of the work are fitted into the groove of the belt when the openable member is closed.

With this configuration, the work can be easily held by the belt by closing the open / close member after the belt is positioned on both sides in the radial direction of the work with the open / close member opened.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to double-side grinding of a semiconductor wafer will be described below with reference to the drawings.

FIG. 1 shows the overall structure of a double-side grinding apparatus. This double-sided grinding apparatus is intended for both a work on which a positioning flat portion is not formed and a work on which the flat portion is formed. The double-sided grinding machine is a work rotating device as a work rotating means on the horizontal shaft double-sided surface grinding machine (1).
(2) is added, and details of the rotation device (2) are shown in FIGS. In the description of this embodiment, the front side of the sheet of FIG. 1 is the front, the back side is the rear, and the left and right when viewed from the front to the rear, that is, the left and right of FIG.

The grinding machine (1) comprises a horizontal bed (3) and left and right grinding heads (4) mounted on the upper surface of the bed (3).
(5) is provided. The respective grindstone heads (4) and (5) can be moved in the left-right direction independently of each other by appropriate driving means (not shown). Horizontal grinding wheel shafts (6) and (7) are rotatably supported in the respective grinding wheel heads (4) and (5). The axis of the left and right whetstone shafts (6) and (7) extends in the left-right direction.
Are on two common horizontal lines. A cup-shaped left grinding wheel (8) is fixed to the tip of the grinding wheel shaft (6) projecting to the right from the left grinding wheel head (4), and the grinding wheel shaft (7) projecting to the left from the right grinding wheel head (5). The right side grinding wheel (9) of the same shape and the same size is fixed to the tip of (). The annular vertical right end surface of the left grinding wheel (8) is a left circular grinding surface (8a), and the annular vertical left end surface of the right grinding wheel (9) is a right circular grinding surface (9a). ) (9a) are opposed to each other in a parallel state. In the case of this embodiment, the outer circumferences of the grinding wheels (8) and (9) and the outer circumferences of the ground surfaces (8a) and (9a) coincide. Left and right whetstone head
When at least one of (4) and (5) moves in the left-right direction, the left and right grinding wheels (8) and (9) relatively move in the left-right direction, that is, in the axial direction. The right and left grinding wheel shafts (6) and (7) are rotated at the same speed in opposite directions by appropriate driving means (not shown). As a result, the left and right grinding wheels (8) and (9) are rotated at the same speed in opposite directions. Rotated with. The other parts of the grinding machine (1) can be configured in the same manner as a known horizontal-axis double-ended surface grinding machine.

The rotation device (2) is a work (wafer) (W)
The processing surfaces (a) and (b) on both sides face the left and right grinding surfaces (8a) and (9a), and a part and center of the outer periphery of the work (W).
As (c) is located inside the outer circumference of the grinding surface (8a) (9a),
The workpiece (W) is vertically supported between the left and right grinding surfaces (8a) and (9a) and is rotated.A horizontal plate-like shape extending back and forth at a position slightly higher than the grindstone heads (4) and (5). Mounted on base (10).

The base (10) is fixed to the bed (3) via a suitable support (11) or the like which does not hinder the movement of the grinding heads (4) and (5). Is installed. The moving member (12) is moved in the front-rear direction along the upper surface of the base (10) by a suitable driving means (not shown). The moving member (12) extends vertically upward at the right end, and a vertical plate-like elevating member (13) extending vertically is attached to the right side surface thereof. The elevating member (13) is moved up and down along the right side surface of the moving member (12) by a suitable driving means (not shown).

The lifting member (13) is provided on the right side surface of the lifting member (13).
A pair of front and rear opening / closing members (14) in parallel with a plate and an air cylinder (15) for opening / closing the opening / closing members are mounted. Pins (16) extending horizontally to the right are fixed to the front and rear two places at the lower end of the elevating member (13). Each is rotatably mounted. The cylinder (15) is attached downward at the center in the front-rear direction of the upper part of the elevating member (13), and the tip (lower end) of the cylinder rod (15a) is opened and closed via a link (17). The upper end of the member (14) is connected to a portion closer to the inside in the front-rear direction. Lifting member just below the cylinder (15)
A stopper (18) for regulating the rod (15a) is fixed to the lower end of (13) so that the vertical position can be adjusted. Rod (1
When 5a) extends and moves to the lower end position where it hits the stopper (18), the pair of opening / closing members (14) pivots to a closed position where the lower part is closed and the whole is substantially vertical as shown in FIG. When the rod (15a) contracts and moves to the upper end position which is separated from the stopper (18) by a predetermined distance, the pair of opening / closing members (14)
As shown in FIG. 6, the lower part opens back and forth and rotates to an open position where the whole becomes an eight-letter shape.

Each of the opening and closing members (14) has a three-groove roller (19) on a right side surface of a portion protruding below the elevating member (13), each of which rotates about an axis extending horizontally to the right. (2
0) is attached, and three rollers (19) (2) of each opening / closing member (14) are attached.
Endless position holding belts (21) and (22) are wound around 0). The belts (21) and (22) support the outer periphery of the work (W) protruding from between the grindstones (8) and (9) in the axial direction and the radial direction by sandwiching the outer periphery from both sides in the radial direction (front-back direction). At the same time, the work (W) is rotated, and is made of a suitable flexible material such as rubber. Grooves (23) are formed on the outer peripheral surface of each of the belts (21) and (22) to fit the outer peripheral portion of the work (W) and support it in the axial and radial directions. Groove
The cross section of (23) has a trapezoidal shape with a wider bottom, and the width of the opening in the left-right direction is slightly smaller than the thickness of the work (W). Rollers (19) and (20) are provided at two locations, inside the front and rear direction above and below the downwardly projecting portion of the opening / closing member (14), and at one location outside the front and rear direction at the middle of the same height. Have been. The three rollers (20) of the rear opening / closing member (14) and the two rollers (19) on the rear side of the front opening / closing member (14) are connected to the opening / closing member (1).
The driven belt is a driven guide roller that rotates freely around a pin (24) fixed to 4), and the rear belt (22) is a driven belt that moves in the length direction as the work (W) rotates. One roller (19) on the front side of the front opening / closing member (14) is a driving roller driven by an electric motor (25), and the front belt (21) applied to the roller is driven in the length direction. This is a drive belt that rotates the work (W). Front opening / closing member (1
An elongated hole (26) extending in the front-rear direction at the closed position is formed in the downwardly protruding portion of (4), and the elongated hole (26) is a portion of the distal end (right end side) of the motor (25) disposed horizontally and rightward. But the long hole (2
6) It is mounted so that it can move in the length direction (front-back direction) but does not move in the axial direction (left-right direction). A drive roller (19) is fixed to a distal end of a motor shaft (not shown) projecting rightward from the opening / closing member (14). The motor (2) is attached to the left side surface of the lower part of the front opening / closing member (14).
A spring built-in plunger (27) for biasing 5) forward is provided, whereby the drive roller (19) is biased forward,
A predetermined tension is applied to the drive belt (21).

In the case of this embodiment, the outer diameter of the grindstones (8) and (9) is about 70% of the outer diameter of the work (W). It is located slightly inside (below) the outer circumference of the grinding surfaces (8a) (9a).

Although not shown, a work carrying-in device and a work carrying-out device are provided at appropriate places behind the grinding machine (1), and the base (10) of the rotation device (2) is provided with these carrying-in devices and It extends to above the unloading device.

In the above-mentioned grinding apparatus, the work of grinding the work (W) is performed, for example, as follows.

During the grinding operation, the left and right grinding wheels (8) and (9) are constantly rotating. At the start of the work, the left and right whetstones (8) and (9) move to the standby position separated to the left and right, and the elevating member (13)
The lowermost part of 4) is raised to the standby position located above the grindstones (8) and (9), and the front and rear opening and closing members (14) are open to the open position. First, in such a state, the moving member (12) moves to a position above the work loading device. In the work loading device,
The work (W) is supplied to a predetermined carry-in position in a vertical state with the processing surfaces (a) and (b) facing left and right one by one. Moving member (12)
Stops when the belts (21) and (22) of the opening / closing member (14) in the open position come directly above the work (W) in the carry-in position, and then the elevating member (13) moves the predetermined work Descend to the position. As a result, the work (W) enters the space between the front and rear belts (21) and (22). At this time, as shown in FIG. 6, the facing portions of the front and rear belts (21) and (22) are separated from the front and rear outer peripheral portions of the work (W) and are linear. Next, the lifting member (13)
Is lowered to the work loading position, and the cylinder rod (15a) extends and abuts the stopper (18).
Closes to the closed position. When the opening / closing member (14) is closed to the closed position, the front and rear widths of the opposed portions of the front and rear belts (21) and (22) are
(W) is smaller than the diameter of the work (W).
1) The groove (23) fits into the groove (23), and the opposing portions of the belts (21) and (22) made of a flexible material are bent outward in the front-rear direction along the outer periphery of the work (W). In the case of this embodiment, when the opening / closing member (14) is closed to the closed position, each belt (21) (22)
About one-fourth of the circumference of the work (W) is fitted into the groove (23), and the work (W) is held by the belts (21) and (22). When the opening / closing member (14) is closed to the closed position, the elevating member
(13) goes up to the standby position. This allows the work (W)
Is held by the belts (21) and (22) and lifted from the work loading device.

When the elevating member (13) rises to the standby position, the moving member (12) moves to a position above a line connecting the left and right grinding wheels (8) and (9) and stops. When the moving member (12) stops, the elevating member (13) moves down to a predetermined grinding operation position, and the drive roller (19) rotates. As the drive roller (19) rotates, the drive belt (21) is driven in the length direction, and the opposing portion moves in the circumferential direction of the work (W). And
The outer periphery of the work (W) stuck in the groove (23) of the belt (21) is moved in the circumferential direction by frictional force between the work (W) and the belt (21), thereby rotating the work (W). Can be
Due to the rotation of the work (W), the outer peripheral portion of the work (W) stuck in the groove (23) of the driven belt (22) also moves in the circumferential direction, and the opposing portion of the driven belt (22) and the work (W) move. The workpiece (W) is moved in the circumferential direction by the frictional force between the belt (22)
Is moved in the length direction. Thus, the work (W) rotates about its center (c). Also,
When the lifting member (13) is lowered to the grinding work position,
(W) enters the space between the left and right grinding wheels (8) and (9), and as shown in FIG. 3, the center (c) of the work (W) is at the top of the outer circumference of the grinding surface (8a) (9a). Located slightly below (inside).

When the elevating member (13) is lowered to the grinding operation position, the grinding wheels (8) and (9) are moved in a direction approaching each other, and the grinding surfaces (8a) and (9a) are moved to the corresponding processing surfaces (a ) (b). As a result, the lower part of the work (W)
(8) sandwiched between (9) and part of the lower outer periphery of the work (W) and the center
(c) are located inside the outer circumference of the grinding surfaces (8a) and (9a). Since the front-rear distance between the front and rear opening and closing members (14) in the closed position is larger than the outer diameter of the grindstones (8) and (9), the grinding stones (8) and (9) do not interfere with the opening and closing member (14). The grindstones (8) and (9) are moved to a predetermined position determined by the finished dimension of the work (W), and stopped at the position for a predetermined time. In the meantime, as the grindstones (8) and (9) rotate, the processing surfaces (a) and (b) of the work (W) in contact with the ground surfaces (8a) and (9a) are ground, and the work ( W)
The workpiece rotates by rotating with the part of the outer circumference and the center (1) positioned inside the outer circumference of the grinding surfaces (8a) and (9a).
While (W) makes one rotation, the entire surface of the work (W) passes between the grinding surfaces (8a) and (9a) on the machining surfaces (a) and (b), and As a result, while the work (W) rotates several times, the entire surfaces of the processing surfaces (a) and (b) on both surfaces are simultaneously ground. During the grinding, if necessary, the lifting member (13) is reciprocated in the vertical direction, whereby the work (W) is moved in the vertical direction, that is, parallel to the grinding surfaces (8a) and (9a). Center of work (W)
Reciprocate in the direction connecting (c) and the axes of the grinding wheels (8) and (9).
This reciprocating movement is part of the lower circumference of the work (W) and the center.
(c) is always performed within a range located inside the outer periphery of the grinding surfaces (8a) and (9a). For example, the stroke of the reciprocating movement is about 5 mm. By reciprocating the work (W) in this manner, the flatness and surface roughness of the center of the work (W) can be particularly improved.

When the grinding of the work (W) is completed, the grinding wheel (8)
(9) moves away from the work (W) and further moves to the left and right standby positions. When the grindstones (8) and (9) separate from the work (W), the drive roller (19) stops rotating, and the elevating member (13) moves up to the standby position. When the drive roller (19) stops, the belts (21) and (22) and the work (W) also stop. Lifting member (1
When 3) moves up to the standby position, the moving member (12) moves to a position above the work unloading device, and positions the work (W) just above a predetermined unloading position. When the moving member (12) stops,
The elevating member (13) descends to a predetermined carry-out position, the cylinder rod (15a) contracts, and the opening / closing member (14) opens to the open position. As a result, the work (W) separates from the belts (21) and (22),
It is moved to the unloading position and unloaded by the unloading device. When the opening / closing member (14) is opened and the work (W) is released, the lifting member (1
3) is raised to the standby position, and thereafter, the above operation is repeated to perform grinding one after another.

When the work (W) is reciprocated during the grinding, the direction of the reciprocation is determined by the center of the work (W) as described above.
A direction connecting (c) to the axis of the grindstones (8) and (9) or a direction close to this is desirable, but it may be reciprocated in another direction parallel to the grinding surfaces (8a) and (9a).

The wafer has a perfect circular shape without a positioning flat portion as shown by a solid line in FIG. 3 and a positioning flat portion (f ) Are formed. However, in the above-described grinding apparatus, the outer peripheral portion of the wafer is fitted into the grooves (23) of the belts (21) and (22) made of a flexible material, and the belts (21) and (22) conform to the outer peripheral shape of the wafer. Therefore, not only a wafer having no positioning flat portion but also a wafer on which the positioning flat portion is formed, the outer peripheral portion can be reliably supported and rotated.

Normally, the left and right grinding wheels (8) and (9) are rotated at the same speed as in the above embodiment, but for example, it is desired to change the grinding allowance distribution on the left and right processing surfaces (a) and (b). In some cases,
In some cases, the grinding speed can be changed by changing the rotation speed of the left and right grinding wheels (8) and (9). It is also possible to grind the left and right grinding wheels (8) and (9) by rotating them in the same direction.

A drive roller (19) for driving a drive belt (21)
May be plural. Also, a pair of belts (21) (2
Both of 2) may be used as drive belts.

In the above embodiment, the pair of opening / closing members (14) are opened and closed by rotation, but may be opened and closed by, for example, parallel movement. In addition, belt (2
1) The support means of (22) is optional, and does not necessarily need to be attached to the opening / closing member.

In the above embodiment, the abscissa double-sided grinding apparatus in which the axis of the grinding wheel is horizontal is shown. However, the vertical axis in which the axis of the grinding wheel is vertical has the same configuration as described above. You can also.

The present invention can also be applied to the grinding of a thin disk-shaped work other than a semiconductor wafer.

[Brief description of the drawings]

FIG. 1 is a schematic front view of a double-side grinding device showing an embodiment of the present invention.

FIG. 2 is an enlarged front view showing a main part of the workpiece rotation device of FIG. 1;

FIG. 3 is a sectional view taken along line III-III of FIG. 2;

FIG. 4 is a sectional view taken along line IV-IV in FIG. 3;

FIG. 5 is a sectional view showing a part of FIG. 4 in a further enlarged manner.

FIG. 6 is a drawing corresponding to FIG. 3, showing a state in which an opening / closing member is opened.

[Explanation of symbols]

 (2) Work rotation device (means) (8) (9) Grinding wheel (8a) (9a) Grinding surface (14) Opening / closing member (21) (22) Position holding belt (23) Groove (W) Work (semiconductor wafer ) (A) (b) Machined surface (c) Center

Claims (2)

[Claims] 1. A pair of grinding wheels, which are arranged so that the circular grinding surfaces of the end surfaces face each other and are relatively movable in the axial direction and are rotated, and the processing surfaces of both surfaces of a thin disk-shaped work are provided. The work is supported and rotated between the grinding surfaces so that the grinding surfaces of the pair of grinding wheels are respectively opposed to each other and a part and the center of the outer periphery of the work are located inside the outer periphery of the grinding surface. Work rotation means for the work, the work rotation means sandwiches the portion of the work that is outside from between the grinding wheels from both sides in the radial direction and can move in the circumferential direction of the work. And a pair of position holding belts arranged at
Grooves are provided for supporting the work in the axial direction and the radial direction by fitting the outer peripheral portion of the work, and at least one of the belts rotates the work by being driven in the circumferential direction of the work. A double-side grinding apparatus for a thin disk-shaped work, which is a drive belt. 2. A pair of position holding belts are attached to a pair of openable and closable members, respectively. When the openable and closable members are closed, outer circumferential portions on both sides in the radial direction of the work are in the groove of the belt. The double-sided grinding apparatus for a thin disk-shaped workpiece according to claim 1, wherein the grinding apparatus is adapted to be fitted.