JP2001326196A - Substrate grinding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate grinding and lapping device which gives substrates having surfaces on which no spiral streaks are left. SOLUTION: A substrate grinding and lapping apparatus is provided with an index table 8 partitionedly sorted into substrate housing cassettes 3 and 4, a substrate transfer robot 5, a temporary mounting stand 6, a cleaning mechanism 7, a loading/unloading zone S1, a first grinding zone S2, a second grinding zone S3 and a lapping zone S4, four substrate chucking mechanisms 9a, 9b, 9c and 9d, a first grinding means 11 which is positioned on the zone S2 and is provided with a cup-wheel type roughly grinding whetstone, a second grinding means 12 which is positioned on the zone S3 and is provided with a cup-wheel type medium-finishing grinding whetstone, a lapping means 13 which is positioned on the zone S4 and is provided with a flat whetstone for finishing borne by a veritable axis, a chuck cleaning mechanism 14, a dressing mechanism 15 and a second transfer means 16 which transfers substrates on the stand 6 on the mechanisms 9a, 9b, 9c and 9d which are positioned on the zone S1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding and lapping apparatus for providing a ground substrate having no spiral spiral marks left on the surface of the substrate.

[0002]

2. Description of the Related Art It has been practiced to grind a wafer sliced by a cup wheel type grindstone having a coarse grindstone to reduce its thickness (Japanese Patent Application Laid-Open No. H11-307489).
In order to reduce the throughput time of the substrate in the grinding process, an index table equipped with a plurality of substrate chucks, a cup wheel type first grinding wheel, and a grinding device provided with a cup wheel type second grinding wheel are proposed. (Japanese Patent Laid-Open Nos. 10-172932 and 11-30748).
No. 9). In this index table type grinding machine, # 300 to # 600 coarse grindstones are used for the first grinding wheel, and # 800 to 2000 fine grindstones are used for the second grinding wheel.

However, in the grinding method using a cup wheel-type grindstone, spiral streaks remain on the ground surface of the wafer, and the strength of the wafer is low. In order to eliminate the streaks, the ground surface is made to have a matte surface using an elastic flat whetstone, the ground surface is flattened by etching, or is polished with a polishing pad to be mirror-finished. These satin finishing, etching, and polishing are performed by a device different from the grinding device.

[0004]

If at least one of these processing means is incorporated in a grinding apparatus, a substrate free of these streaks can be obtained, and it is necessary to provide a separately installed grinding apparatus, etching apparatus and polishing apparatus. And the print footprint of the device is small.

According to the present invention, a cup wheel type grindstone is used for the first grinding and the second grinding, a disc-shaped grindstone (plate grindstone) is used as a grindstone for final grinding, and the substrate is lapped to form a strip on the back surface. An object of the present invention is to provide a grinding device that provides a substrate without leaving a trace.

[0006]

According to a first aspect of the present invention, there is provided a substrate storage cassette, a substrate transfer robot disposed in front of the storage cassette, a temporary table and a spin cleaning mechanism disposed on the left and right sides of the transfer robot. An index table arranged in front of the transfer robot, the temporary table, and the cleaning mechanism, and divided into a loading / unloading zone, a first grinding zone, a second grinding zone, and a lap zone. Table, four horizontally rotatable substrate chuck mechanisms provided on the same circumference and at equal intervals of 90 degrees with respect to the rotation axis of the index table, provided above the index table. And a first grinding means provided on a spindle shaft with a cup wheel type coarse grinding wheel provided opposite to a chuck mechanism located in the first grinding zone, and a chuck mechanism located in the second grinding zone. A cup wheel type medium finishing grinding wheel provided on the opposite side is provided with a second grinding means provided on a spindle shaft and a finish supported on a swingable shaft for lapping a substrate on a chuck mechanism located in a lap zone. Lap means having a flat grindstone for use, a chuck cleaning mechanism for cleaning a chuck mechanism located in a loading / unloading zone, a dressing mechanism for a flat grindstone for finishing the lap means,
And a second transport means for transporting the substrate on the temporary table onto a chuck mechanism located in a loading / unloading zone.

By using an index table type grinding device, the throughput time of the substrate is reduced. Further, by using a swing type lapping grindstone for the mirror finish of the back surface of the substrate, the streaks disappear, and a processed substrate having a back surface of the matte surface can be obtained.

According to a second aspect of the present invention, in the apparatus for grinding a substrate, the disk-shaped flat whetstone of the lapping means has a whetstone particle size of #.
No. 600-2000, characterized in that it is a flat grindstone provided with a groove having a width of 0.3 to 2 mm on the surface side on which the substrate is wrapped so as to communicate with the outer periphery of the flat grindstone.

Debris ground and lapped by the grooves provided on the surface of the flat whetstone is easily discharged from the substrate surface together with the grinding fluid.

According to a third aspect of the present invention, in the above-described substrate grinding apparatus, the cup wheel type coarse grinding wheel of the first grinding means has a grinding wheel having a grain size of # 300 to 800, and the second grinding means has a grain size of # 300 to 800. The grain size of the cup wheel type medium finishing grinding wheel is larger than the grain size of the cup wheel type coarse grinding wheel of the first grinding means, and is characterized by # 600 to # 2400.

In order to shorten the throughput time of the substrate,
In the first grinding zone, a coarse cup wheel-type grindstone is used to increase the substrate grinding speed (the speed at which the substrate is reduced in the thickness direction by grinding) to shorten the throughput time of the entire processing time. In the second grinding zone, the depth of the scratches can be reduced by using a fine cup wheel type grindstone, and the lap processing time in the next step can be shortened.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 is a plan view of the grinding / lapping device of the present invention, FIG. 2 is a front view as viewed from the line II in FIG. 1, and FIG. 3 is a plan view of a flat grindstone.

In FIG. 1, 1 is a substrate grinding / lapping apparatus, 2 is a base, 3 and 4 are substrate storage cassettes, and 5 is a substrate transport robot, which is arranged in front of the storage cassettes 3 and 4. Reference numeral 6 denotes a temporary mounting table, 7 denotes a cleaning mechanism, both of which are arranged on a line on the left and right sides of the transfer robot. 8 is an index table
A loading / unloading zone S1, a first grinding zone S2, a second grinding zone S3, and a wrap zone S4. Is divided into sections.

The index table 8 is provided on the same circumference as the rotation axis 8a of the index table and at 9
Four substrate chuck mechanisms 9a, 9b, 9c, 9d are provided at equal intervals of 0 degrees and rotatable in the horizontal direction. Above the index table 8, three processing means 11, 12, and 13 are provided. One is a first grinding means 11 provided with a cup wheel type rough grinding wheel 11a provided on a spindle shaft 11b opposed to a chuck mechanism located in a first grinding zone S2, and a second grinding zone S.
3 and a cup wheel-type medium finishing grinding wheel 12a provided opposite to the chuck mechanism
And a lapping means 13 comprising a finishing flat grindstone 13a supported on a swingable shaft 13b for lapping a substrate on a chuck mechanism located in a lap zone S4.

A chuck cleaning mechanism 14 cleans the chuck mechanism located in the loading / unloading zone S1. A dressing mechanism 15 dresses the surface of the finishing flat grindstone of the lapping means 13. Reference numeral 16 denotes a second transfer means for transferring the substrate on the temporary table 6 onto a chuck mechanism located in the loading / unloading zone S1.

The cup wheel type grindstone is disclosed in, for example,
As disclosed in 1-188644, JP-A-2000-94342, and Japanese Patent No. 2867380, grindstone pieces of a specific order are arranged on a ring-shaped pedestal with a gap (slit) provided. Grinding fluid is supplied to the groove provided inside, is supplied to the substrate from the hole provided diagonally at the bottom of the groove, flows on the substrate surface under centrifugal force due to the rotation of the substrate, and is supplied from the slit to the outer periphery of the substrate Is done. The grindstone pieces are formed by hardening abrasive grains with a resin, and the grindstones having a coarse grain size of # 300 to # 800 in the first grinding are used to increase the grinding speed. In the second grinding, # 600 to # 2400 finer than that used in the first grinding is used to reduce the depth of scratches and reduce the thickness to be ground in the lapping process.

As the flat whetstone, for example, whetstone particle size # 600
A # 2000 resin bond grindstone is used. The thickness is generally 3 to 35 mm, and it is preferable that a groove 13 c having a width of 0.3 to 2 mm is provided on the surface side on which the substrate is wrapped so as to communicate with the outer periphery of the flat grindstone (see FIG. 3). Lapping debris is driven from the substrate surface to the outer periphery through the groove. In order to form the groove and the flow path of the grinding fluid, the flat whetstone may be formed by combining the divided whetstone pieces.

The spindle shafts of the first grinding means and the second grinding means can be moved up and down. The flat whetstone of the lapping means is swingable. Although FIG. 1 shows an example of swinging in an arc shape, the lapping means is reciprocated linearly using a ball screw, a moving body screwed to the ball screw and supporting the lapping means, and a motor. It may be designed to do so. The spiral streak of the ground substrate disappears by the lapping process.

Substrate chuck mechanisms 9a, 9b, 9c, 9
d is a hollow shaft rotatable independently of the rotation of the index table 8 and a porous ceramic plate supported on the hollow shaft. As is well known, the hollow shaft is depressurized, pressurized air, or flush water. Can be supplied. The substrate can be adsorbed to the chuck mechanism by reducing the pressure in the hollow shaft. Supply of pressurized air and cleaning water facilitates peeling of the ground or lapped substrate from the chuck mechanism.

As described above, the index table 8 includes a loading / unloading zone and a first grinding zone.
, A second grinding zone and a lap zone, and are rotated by 90 degrees. The rotating shafts 9e, 9e for supporting the porous ceramic plates of each chuck mechanism are fixed to the outside of the rotating shaft 8a of the index table by the support frame. Also move 90 degrees.

Loading / unloading zone S
In 1, cleaning of the chuck mechanism 9 by the chuck cleaning mechanism 14 and loading of the substrate from the temporary mounting table 6 are performed. In loading the substrates, the substrates stored in the storage cassette 3 are carried out by the arm of the transfer robot 5 and temporarily placed on the temporary mounting table 6 for cleaning the chuck mechanism and rotating the index table by 90 degrees. For a while, and then the second transport unit 1
The substrate on the temporary mounting table 6 is transferred to the chuck mechanism 9 of the loading / unloading zone S1 by the suction pad 6 and sucked by the porous ceramics plate of the chuck mechanism 9.

The chuck cleaning mechanism 14 is capable of reciprocating in the front-rear direction (Y-axis direction). When the chuck cleaning mechanism 14 reaches the chuck mechanism 9, the shaft 14a descends to bring the ceramic grindstone 14b into contact with the chuck mechanism. The shaft 14a is rotated while the cleaning water is supplied onto the surface 9, and the shaft 9e of the chuck mechanism is also rotated to clean the surface of the chuck mechanism. When the cleaning of the chuck mechanism is completed, the shaft 14a moves up,
The chuck cleaning mechanism is retracted.

In the first grinding zone S2, the substrate is roughly ground. The number of rotations of the chuck mechanism is 100-1000 rpm
m, the rotation speed of the cup wheel type grinding wheel 11a is 600 to 6
000 rpm. In the second grinding zone S3, the substrate is semi-finished. The number of rotations of the chuck mechanism is 100 to 6
00 rpm, the number of rotation of the cup wheel type grinding wheel 12a is 2
It is 00 to 2000 rpm. In the lapping zone S4, the spiral streaks of the substrate are eliminated, and the surface of the substrate is finished to a satin finish. The rotation speed of the chuck mechanism is 20-100r
pm and the rotation speed of the flat grindstone 13a is 40 to 200 rpm.

When the lapping of the substrate is completed, the substrate is transferred to the substrate cleaning mechanism 7 by the transfer robot 5. The substrate placed on the spinner table is rotated by rotating the spinner, and the surface is scrub-cleaned using a brush and cleaning water, followed by rinsing and spin-drying. Ultrasonic waves may be applied during scrub cleaning. On the other hand, after the lap-processed substrate is carried out, the lap processing means 13 is rotated to move onto the dressing mechanism 15 and the flat grindstone 13 is moved.
dressing mechanism 15 rotating while rotating a
And dressing is performed.

In the substrate chuck mechanism 9, 90 is a pure water supply pipe, 91 is a pump, 92 is a support plate of a porous ceramic plate, and a cylindrical concave portion 93 is formed at the center thereof. A fluid passage 94 is provided in the vertical direction. The fluid passage 94 is connected to a pipe 90 via a sleeve 95 having an electromagnetic chuck function, and is connected to a switching valve 96. One pipe 97 is connected to a vacuum pump and the other pipe 98 is connected to pure water. Connected to the supply tank. 99 is a housing, 100 is a clutch mechanism, and 101 is a motor. Air motor 101
The porous ceramic plate can be rotated in the horizontal direction by lifting with the cylinder 102, connecting the chucks 14 and 14a, and driving the motor 101.

When the lapping of the substrate by the disk-shaped flat grindstone is completed, the valve 96 is switched, pure water is supplied to the fluid passage 94, and the substrate w is lifted from the porous ceramic plate. Facilitates peeling.

FIG. 1 shows an example in which the flat grindstone swings about a shaft. However, the flat grindstone may reciprocate in the front-rear direction. More specifically, a flat grindstone centered on a spindle shaft using a ball screw, a mechanism for moving the disc-shaped grindstone in the front-rear direction by rotating the ball screw, and a mechanism for raising and lowering the flat grindstone are provided. Things. The swing of the flat grindstone is performed so that a spiral streak does not remain on the surface of the substrate wrapped by the flat grindstone, and is performed such that the outer periphery of the flat grindstone passes through the center point of the substrate. The feed rate of the flat whetstone in the left-right direction is preferably 0.1 to 1 m / min.

The wrapped substrate is transferred to the cleaning mechanism 7 by the transfer robot 5. For the transfer, it is preferable to use a third transfer robot or a transfer pad instead of the transfer robot 5. Alternatively, a two-arm robot is used as the transfer robot 5, and one arm is used only for loading from the storage cassette 3 to the temporary mounting table 6 and for transferring clean wafers from the cleaning mechanism 7 to the storage cassette 4. ,
The other arm is used only for transferring the dirty substrate from the lapping zone S4 to the cleaning mechanism 7. The cleaned substrate is
The sheet is conveyed into the storage cassette 4 and is unloaded.

[0029]

EXAMPLE 1 Using a grinding and lapping apparatus shown in FIG. 1, a sliced silicon wafer having a thickness of 220 μm and a diameter of 200 mm was ground and lapped through the following steps to a thickness of about 194 μm.
Thus, a wafer having a satin-finished surface was obtained. First step: The cup wheel type coarse grinding wheel of the first grinding means has a grinding wheel having a grain size of # 325, and the cup wheel type medium finishing grinding wheel of the second grinding means has a grinding wheel having a grain size of # 325. The disk-shaped flat whetstone of the lapping means was # 1500 and had a whetstone particle size of # 1500 and had a width of 1.2 on the surface side.
A combination flat grindstone provided so that a groove of mm was formed on the outer periphery of the flat grindstone was used.

The silicon wafer stored in the storage cassette was carried out by the arm of the first transfer robot, the arm was turned over, and once put on the temporary table to stand by. After the chuck mechanism of the loading / unloading zone S1 is cleaned by the chuck cleaning mechanism, and the chuck cleaning mechanism is retracted, the wafer on the temporary table is sucked by the second transport pad, and the second transport pad is rotated. Then, the wafer was moved onto the chucking mechanism of the loading / unloading zone S1 and placed thereon, and then the porous ceramics plate of the chucking mechanism was suctioned by depressurizing to load the wafer.

Second step: After rotating the index table 90 degrees clockwise to move the wafer to the first grinding zone, the chuck mechanism for sucking the wafer is moved to the sixth position.
The cup wheel-type coarse grinding wheel is rotated at 3000 rpm while rotating at 00 rpm, and the cup wheel-type coarse grinding wheel rotating at 3000 rpm is lowered to perform a rough grinding for 2 minutes to grind a thickness of about 20 μm. Was raised. Meanwhile, as described above, a new silicon wafer from the cassette is placed on the temporary table by the transfer robot, and
The chuck mechanism of the loading / unloading zone S1 is cleaned by the chuck cleaning mechanism, and after the chuck cleaning mechanism is retracted, the wafer on the temporary table is sucked by the transfer pad, and the transfer pad is rotated to load. / Unro
After being moved onto the chucking mechanism of the loading zone S1 and placed, the porous ceramics plate of the chucking mechanism was adsorbed by depressurizing to load the wafer.

Third step: The first ground wafer is moved to the second grinding zone by rotating the index table 90 degrees clockwise, and the loading / unloading zone S1 is rotated. The wafer on the chuck mechanism was moved to the first grinding zone. In the second grinding zone, the chuck mechanism holding the wafer is rotated at 400 rpm, and the cup wheel type semi-finished grinding wheel rotating at 2000 rpm is lowered on the surface of the wafer.
Rough grinding was performed for 5 minutes, a thickness of about 5 μm was ground, and the cup wheel type semi-finished grinding wheel was raised. In the first grinding zone, the chuck mechanism is rotated at 600 rpm, the cup wheel type rough grinding wheel rotating at 3000 rpm is lowered on the surface of the wafer, and rough grinding is performed for 2 minutes to obtain a thickness of about 20 μm. And grind the cup
The coarse grinding wheel was raised.

Meanwhile, as described above, a silicon wafer newer than the cassette is placed on the temporary mounting table by the transfer robot, and the chuck mechanism of the loading / unloading zone S1 is cleaned by the chuck cleaning mechanism. Then, the wafer on the temporary table is sucked by the transfer pad, and the transfer pad is rotated to load / unload the wafer.
After the wafer was moved onto the chuck mechanism of the unloading zone S1 and placed, the porous ceramics plate of the chuck mechanism was adsorbed by depressurizing to load the wafer.

Fourth step: The index table is rotated clockwise by 90 degrees to move the second ground wafer to the lap zone, and the first ground wafer to the second grinding zone. Then, the wafer on the chuck mechanism of the loading / unloading zone S1 was moved to the first grinding zone. In the lap zone, the surface of the semi-finished device wafer rotating at 60 rpm is rotated for 100 r.
Lapping with a flat whetstone rotating at pm for 2 minutes and thickness of about 1
μm (wrapping step). Then, after raising the flat grindstone, the lap-processed wafer was sucked by the third transfer pad, and was rotated and placed on the spinner table of the cleaning mechanism. The wafer was subjected to brush scrub cleaning on the cleaning mechanism, followed by rinsing cleaning and spin drying (cleaning step).

Next, the ground and lapped wafer dried by the first transfer robot was loaded into a cassette (unloading step). On the other hand, in the second grinding zone, the chuck mechanism for sucking the wafer is rotated at 400 rpm, and the cup wheel type semi-finished grinding wheel rotating at 2000 rpm is lowered on the surface of the wafer. Rough grinding was performed for 5 minutes to grind a thickness of about 5 μm, and the cup wheel type semi-finishing grinding wheel was raised (second grinding step).

In the first grinding zone, the chuck mechanism is set to 60
While rotating at 0 rpm, 3
The cup wheel-type rough grinding wheel rotating at 000 rpm was lowered, rough grinding was performed for 2 minutes, a thickness of about 20 μm was ground, and the cup wheel-type rough grinding wheel was raised (first grinding step).

In the meantime, as described above, a new silicon wafer from the cassette is placed on the temporary mounting table by the transfer robot, and the chuck mechanism of the loading / unloading zone S1 is cleaned by the chuck cleaning mechanism. Then, the wafer on the temporary table is sucked by the transfer pad, and the transfer pad is rotated to load / unload the wafer.
After the wafer was moved onto the chuck mechanism of the unloading zone S1 and placed, the porous ceramics plate of the chuck mechanism was adsorbed by depressurizing to load the wafer (loading step).

Hereinafter, the same operation as in the fourth step is performed in the same manner.
That is, the 90-degree rotation of the index table, the unloading step, the loading step, the first grinding step, the second grinding step, the lapping step, and the cleaning step are repeated. A grinding liquid was supplied to the wafer surface during the grinding and lapping, thereby preventing the temperature of the wafer and the grindstone from rising.

[0039]

According to the present invention, since the lapping means is incorporated in the grinding device, the installation area of the device is small and compact.

[Brief description of the drawings]

FIG. 1 is a plan view of a grinding / lapping device of the present invention.

FIG. 2 is a front view as seen from a line II in FIG. 1;

FIG. 3 is a plan view of a flat whetstone.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Grinding / lapping device w Substrate 2 Base 3,4 Cassette 5 Transfer robot 6 Temporary table 7 Cleaning mechanism 8 Index table 9 Chuck mechanism 11 First grinding means 12 Second grinding means 13 Lapping means 14 Chuck cleaning mechanism 15 Dressing mechanism 16 Second transport means

Claims (3)

[Claims] 1. A substrate storage cassette, a substrate transfer robot disposed in front of the storage cassette, a temporary mounting table and a cleaning mechanism disposed on the left and right sides of the transfer robot, and a temporary storage table and a cleaning mechanism disposed in front of the transfer robot, the temporary storage table and the spin cleaning mechanism. Placed, loading /
An index table divided and divided into an unloading zone, a first grinding zone, a second grinding zone, and a lap zone, on the same circumference as the rotation axis of the index table and at 90 degrees. Four horizontally rotatable substrate chuck mechanisms provided at equal intervals, provided above the index table and opposed to the chuck mechanism located in the first grinding zone. A first grinding means provided with a cup wheel type rough grinding wheel on a spindle shaft, and a cup wheel type medium finishing grinding wheel provided on a spindle shaft provided opposite to a chuck mechanism located in a second grinding zone. Lapping means comprising a flat grinding wheel supported on a swingable shaft for lapping a substrate on a chuck mechanism located in a lap zone, wherein
Chuck cleaning mechanism for cleaning the chuck mechanism located in the unloading zone, dressing mechanism for the finishing flat grindstone of the lap means, and chuck mechanism for positioning the substrate on the temporary mounting table in the loading / unloading zone An apparatus for grinding a substrate, comprising: a second transfer means for transferring the substrate upward. 2. The disk-shaped flat whetstone of the lapping means has a whetstone grain size of # 600 to # 2000, and a groove having a width of 0.3 to 2 mm is formed on the outer surface of the flat whetstone on the surface side on which the substrate is wrapped. The substrate grinding apparatus according to claim 1, wherein the apparatus is a flat grindstone provided so as to communicate therewith. 3. The grain size of the cup wheel type coarse grinding wheel of the first grinding means is # 300 to 800, and the grain size of the cup wheel type medium finishing grinding wheel of the second grinding means is the first. 3. The substrate grinding apparatus according to claim 2, wherein the value is larger than the grain size of the cup wheel type coarse grinding wheel of the grinding means, and the value is # 600 to # 2400.