JPH10284448A - Polishing system for semiconductor wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate dirts between a chuck table and a wafer for preventing, at polishing, crack or dimple of the wafer, by polishing the surface of wafer placed on the upper surface of chuck table after washing the wafer surface contacting to a washed upper surface of the chuck table. SOLUTION: A chuck table 14 which held a wafer W is contaminated at its upper surface with chip, etc., so the upper surface is washed by a washing means 12 at polishing. The wafer W is sucked by a transportation means 8, and is rotated while a washing member 19b on a rotating disk 10a contacts to the wafer W, and the lower surface of the wafer W is washed under water jet from a nozzle. After that, the wafer W is transported onto the chuck table 14, and is sucked and held by the chuck table 14. Then, a turn table 13 is so rotated that the chuck table 14 is positioned directly under a polisher 15, and a polishing grindstone 15b of the polisher 15 is rotated so that the upper surface of wafer W is polished while a polishing liquid is supplied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer polishing system.

[0002]

2. Description of the Related Art Semiconductor wafers formed of Si or the like are:
When both surfaces are polished in wafer making, or when a circuit such as an IC is formed on the front surface, only the back surface is polished. A polishing apparatus provided with a provided polishing grindstone is generally used.

[0003]

However, in a wafer polishing system using such a conventional polishing apparatus, if there is dust between the chuck table and the wafer, the wafer may break during polishing. There is a problem that a depression called a dimple occurs. Therefore,
SUMMARY OF THE INVENTION It is an object of the present invention to provide a semiconductor wafer polishing system capable of preventing breakage and dimples of a wafer during polishing by preventing dust from intervening between a chuck table and a wafer.

[0004]

As a specific means for achieving this object, the present invention provides a method for polishing a semiconductor wafer by placing a wafer on a chuck table of a polishing apparatus and polishing the surface of the wafer with a polishing grindstone. A chuck table cleaning step of cleaning an upper surface of the chuck table, a wafer cleaning step of cleaning a surface of the wafer in contact with the upper surface of the chuck table, and the chuck table cleaning step and the wafer cleaning step are completed. A polishing system for a semiconductor wafer including at least a polishing step of placing a wafer on an upper surface of a chuck table and polishing the surface of the wafer is described. or,
In this polishing system, after polishing the front surface of the semiconductor wafer, the semiconductor wafer is turned over and the back surface is polished.

[0005]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows a polishing apparatus 1 used in a polishing system according to the present invention, in which a wafer mounting area A, a standby area B, a cleaning area C, and a polishing area D are provided.

In the wafer mounting area A, a polygonal (hexagonal) recess 2a is formed at the front center of the bed 2, and the first cassette 3 and the second cassette 2 are formed on both sides of the recess 2a. The cassettes 4 are respectively detachably mounted, and a loading / unloading means 5 is provided in the recess 2a.

The first cassette 3 contains a plurality of wafers W to be polished, and is placed with its opening facing the recess 2a. The second cassette 4 contains the polished wafers. It is placed with its opening facing the recess 2a side as much as possible. In other words, the first and second cassettes 3 and 4 are arranged on opposite sides of the recess 2a with the recess 2a interposed therebetween. However, the present invention is not limited to this. It may be arranged on the adjacent side.

The carrying-in / out means 5 has a support shaft 5a which moves up and down and rotates axially, and a gripping arm 5b attached to the upper end thereof. Have been. The loading / unloading means 5 has a function of loading / unloading wafers into / from the first and second cassettes 3 and 4 and exchanging wafers with the standby area B.

In the waiting area B, a first waiting table 6 and a second waiting table 7 are arranged on both sides, and positioning pins 6a for centering a wafer placed thereon are provided. , 7a are arranged in the circumferential direction.

A first transport means 8 and a second transport means 9 are arranged in a vertically movable and pivotable manner in association with the first and second standby tables 6 and 7. The transfer means has a function of exchanging wafers between the standby area B and the cleaning area C and between the cleaning area C and the polishing area D.

In the cleaning area C, a first cleaning means 10 and a second cleaning means 11 are arranged on both sides, and these cleaning means are provided on the upper surfaces of the rotating disks 10a, 11a with cleaning members 10b such as brushes, etc. 11b. In this case, the first cleaning means 10 is located on the turning arc of the first transport means 8, and the second cleaning means 11 is located on the second transport means 9.
Is located on the swirl arc.

Further, a third cleaning means 11 is provided near the third cleaning means 11.
Of the third cleaning means 12 is provided.
The rotating disk 12b is attached to the tip of an arm 12a that moves up and down and turns, and a cleaning member 12c such as a brush is provided on the lower surface of the rotating disk 12b. The cleaning member S in each cleaning means is not provided on the entire surface of the rotating disk T, for example, as shown in FIG. 3, but is provided in a radial shape at a predetermined angle, and each radiation is curved in an arc shape. Or any other suitable form.

The polishing area D has a turntable 13
A plurality of (four in the figure) chuck tables 14 are disposed along the circumferential direction on the turntable 13, and a first polishing for rough polishing is performed in association with these chuck tables 14. A polishing machine 15 and a second polishing machine 16 for finish polishing are provided side by side.

The first and second polishing machines 15 and 16 have rotating disks 15a and 16a attached to their lower ends, respectively, and have polishing grindstones 15b and 16b mounted on their lower surfaces, respectively. Can be polished at the same time.

Reference numeral 17 denotes a mounting portion for the first and second polishing machines 15 and 16, and a guide rail 17 extending vertically on the front side.
A pair of a and 17b are disposed on the left and right, respectively, and mounting plates 17c and 17d holding the first and second polishing machines 15 and 16 move up and down along these guide rails. Reference numeral 18 denotes a driving motor mounted on the rear side of the mounting portion 17.

In the polishing apparatus 1 configured as described above, first, an unpolished wafer W is unloaded from the first cassette 3 by the loading / unloading means 5 and is transported onto the first standby table 6 and positioned. 6a, and is placed at the center by the pin 6a.

The wafer W is transferred to the first transfer means 8
As shown in FIG. 2, the first cleaning means 10
Cleaning member 1 positioned on the rotating disk 10a
Ob is brought into contact with the wafer W and rotated, and the lower surface of the wafer W is cleaned while spraying water (or a cleaning liquid) from the nozzle 10c. This is to remove dust and the like adhering to the back surface of the wafer W to clean it.

After the cleaning, the first transfer means 8 is turned to transfer the wafer W onto the chuck table 14, and the wafer W is sucked and held by the chuck table 14 (It is important that the upper surface of the chuck table 14 is already cleaned). See below). At this time, the chuck table 14 is on standby in advance at the turning position of the first transfer means 8, that is, on the circumference around the support shaft.

Next, the turntable 13 is rotated to position the chuck table 14 immediately below the first polishing machine 15, and the polishing grindstone 15b of the first polishing machine 15 is rotated to supply the polishing liquid to the wafer. The upper surface of W is roughly polished. At this time, no dust or the like is interposed between the chuck table 14 and the lower surface (clean surface) of the wafer W, so that the wafer W does not crack or dimple (dent) during polishing.

During this polishing operation, the second wafer carried out next is cleaned by the first cleaning means 10 and then held on the subsequent chuck table, and after the polishing is completed, the turntable 13 is rotated. And the first wafer is the second
The second wafer is placed in the first polishing machine 15
Are positioned respectively.

Thereafter, rough polishing and finish polishing are simultaneously performed by the first and second polishing machines 15 and 16, respectively. After the polishing is completed, the turntable 13 is rotated again. The third wafer held on the subsequent chuck table during the polishing operation while being positioned on the polishing machine 16 is positioned on the first polishing machine 15.

After the final polishing, the first wafer is positioned at the turning position of the third cleaning means 12 (in this case, it is preferable to clean the upper surface of the wafer by the third cleaning means 12). It also coincides with the turning position of the second transfer means 9, is sucked by the second transfer means 9 during the next polishing operation, and is positioned just above the second cleaning means 11. The lower surface of the dirty wafer is cleaned, and after the cleaning, the second standby table 7 is cleaned.
It is conveyed upward and is further housed in the second cassette 4 by the carrying-in / out means 5. These series of operations are performed while taking timing with other operations according to the operation steps.

On the other hand, since the upper surface of the chuck table holding the first wafer is contaminated by polishing debris or the like during the polishing process, the third cleaning means 12 is turned to position it directly above the polishing table. The upper surface is thoroughly cleaned by the third cleaning means 12.

This chuck table cleaning step is performed during the above-mentioned polishing operation.
When the rotating table 3 is rotated, the cleaned chuck table is positioned at the standby position for receiving the unpolished wafer.
The unpolished wafer whose lower surface (the surface that contacts the chuck table) has been cleaned as described above is placed on the chuck table. Accordingly, there is no room for dust or the like to intervene between the chuck table and the wafer, and it is possible to prevent cracking of the wafer and occurrence of dimples during polishing as described above.

In this manner, the wafer polishing operation can be performed continuously and efficiently while taking the timing between the steps. When polishing both sides of the wafer, after the single-side polishing is completed as described above, the polished wafer is once returned to the first cassette 3, and after the single-side polishing is completed for all the wafers, the loading / unloading means 5, the wafer is unloaded again, and then the gripping arm 5b is turned over to be transported with the unpolished surface facing upward onto the first standby table 6, polished through the above-described steps, and finally unloaded. The work is completed after being housed in the second cassette 4 by the insertion means 5. Incidentally, the same cleaning means as the third cleaning means 12 may be arranged at the position indicated by the reference numeral 22 in FIG. 1 to clean the upper surface of the chuck table 14 before mounting the wafer.

[0026]

As described above, according to the present invention,
In the semiconductor wafer polishing system, since the dust is configured not to be interposed between the chuck table and the wafer mounted thereon, the wafer is not broken or dimples are generated at the time of polishing, It is possible to provide a high quality wafer and to achieve excellent effects such as significantly improving the yield in the polishing process.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a polishing apparatus used in a polishing system according to the present invention.

FIG. 2 is a schematic sectional view showing an example of a wafer cleaning unit.

FIG. 3 is an explanatory view showing another embodiment of the cleaning member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Polishing device 2 ... Bed 3 ... First cassette 4 ... Second cassette 5 ... Carry-in / out means 6 ... 1st standby table 7 ... 2nd standby table 8 ... 1st conveyance means 9 ... 2nd Transporting means 10 First cleaning means 11 Second cleaning means 12 Third cleaning means 13 Turntable 14 Chuck table 15 First polishing machine 16 Second polishing machine 17 Attachment part 18 ... Drive motor

Claims (2)

[Claims] 1. A semiconductor wafer polishing system for mounting a wafer on a chuck table of a polishing apparatus and polishing a surface of the wafer with a polishing grindstone, wherein: a chuck table cleaning step of cleaning an upper surface of the chuck table; After the wafer cleaning step of cleaning the surface of the wafer that comes into contact with the upper surface of the table, and the chuck table cleaning step and the wafer cleaning step, a wafer is placed on the upper surface of the chuck table and polishing is performed to polish the surface of the wafer. And a polishing system for a semiconductor wafer. 2. The semiconductor wafer polishing system according to claim 1, wherein after polishing the front surface of the semiconductor wafer, the semiconductor wafer is inverted and the back surface is polished.