JPH053184A - Cleaning method of wafer - Google Patents

Abstract

PURPOSE:To prevent stains attached to the rear of a wafer from becoming a contamination source by a method wherein the rear of the wafer is cleaned by a brush after the front of the wafer is cleansed with fluid. CONSTITUTION:Different or the same chemical liquid is sprayed on the mirror surface (front side) 1a of a semiconductor wafer 1 from nozzles 6a, 6b, and 6c at different times or at the same time by a chemical liquid processing device. Then, pure water 5b is sprayed on the mirror surface 1a and the rear 1b of the semiconductor wafer 1 from a nozzle 6 to rinse from a rinsing device 2b. Thereafter, the rear 1b of the semiconductor wafer 1 is cleaned with a brush 9 to remove stains from it as the semiconductor wafer 1 is rotated by a brush cleaning device 7. By this setup, the mirror surface of a semiconductor wafer itself or the mirror surfaces of other semiconductor wafers can be protected against contamination.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer cleaning method, and more particularly to a wafer cleaning method for cleaning a mirror surface of a semiconductor wafer.

[0002]

2. Description of the Related Art Generally, chemical cleaning of a mirror surface of a semiconductor wafer is performed by a dip type process. As shown in FIG. 8, the chemical cleaning by the dip processing is cleaning performed by dipping 25 to 50 semiconductor wafers c into the chemical liquid b in the processing tank a, for example. A carrier d carries a predetermined number of semiconductor wafers c.

However, in the dip processing, when the back surface of the semiconductor wafer c is contaminated with dust, metal, or organic substance, the chemical solution b is used as a medium for the mirror surface of the semiconductor wafer c itself and further for the other semiconductor wafer c. There is a drawback that the surface) is contaminated. In particular, when the processing history is accumulated, dust, metal, and organic substances are accumulated in the chemical liquid, and the cleanliness of the chemical liquid is lowered, and the mirror surface (surface) of the semiconductor wafer c is easily contaminated.

Therefore, as shown in FIG. 9, it has been attempted to adopt a spray type process in which the semiconductor wafer c is rotated with its mirror surface facing upward and the chemical solution b is spray-sprayed onto the mirror surface of the rotating semiconductor wafer c. .. I mean,
This is because there is no possibility that the back surface of the semiconductor wafer c will be contaminated by the spray process, which may contaminate the semiconductor wafer c or the mirror surface of another semiconductor wafer c. In FIG. 9, e is a vacuum chuck for supporting the semiconductor wafer c, which can be rotated by a rotating mechanism (not shown). f is a nozzle for ejecting the chemical liquid b.

[0005]

However, the conventional cleaning method by the spray-type treatment shown in FIG. 9 also has a problem. Although the mirror surface, which is the front surface of the semiconductor wafer c, is cleaned, the semiconductor wafer c is sent to the next process without cleaning the back surface at all, and in this process, the semiconductor wafer c is processed.
The problem is that dust, metal, organic matter, etc. on the back side become pollution sources.

The present invention has been made to solve such a problem, and an object of the present invention is to prevent dirt on the back surface of a wafer from becoming a contamination source in a wafer cleaning method.

[0007]

The wafer cleaning method of the present invention is characterized in that after cleaning the front surface of the wafer with a liquid, at least the back surface of the wafer is cleaned with a brush.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The wafer cleaning method of the present invention will be described in detail below with reference to the illustrated embodiments. 1 (A) to 1 (C) are schematic explanatory views showing the outline of the method for cleaning a wafer of the present invention. In the drawings, 1 is a semiconductor wafer, 1a is a semiconductor wafer 1.
Mirror surface (front surface) of the semiconductor wafer 1, 1b is a back surface of the semiconductor wafer 1, and 2a is a chemical treatment apparatus. Mirror surface (front surface) 1a of semiconductor wafer 1 of
One or a plurality of nozzles 6 for ejecting cleaning chemicals to the
It consists of a, 6b, and 6c.

Reference numeral 2b denotes a rinsing device, which has a plurality of rotating frames 3 for holding the semiconductor wafer 1 at its peripheral edge.
A rotating plate 4 that gives it a rotating force, a rotating frame 3,
The nozzles 6 and 6 eject the rinsing liquid 5b to both front and back surfaces of the semiconductor wafer 1 which is rotated while being held by the nozzles 3.

Reference numeral 7 denotes a brush cleaning device, which comprises a wafer holder 8 which rotates while holding the semiconductor wafer 1, and a brush 9 which cleans the back surface 1b of the semiconductor wafer 1. In this embodiment, the brush 9 is also used on the (mirror surface) surface of the semiconductor wafer 1.
It is designed to be cleaned at the same time as the back side.

In this wafer cleaning method, first, as shown in FIG. 1A, a plurality of nozzles 6a, 6b, 6 are applied to a mirror surface (front surface) 1a of a semiconductor wafer 1 by a chemical treatment device 2a.
At different times or at the same time, different or the same chemical solution 5a is jetted from c to perform chemical solution cleaning.

Next, as shown in FIG.
The pure water 5b is jetted and rinsed by the nozzles 6 and 6 onto the mirror surface 1a and the back surface 1b of the semiconductor wafer 1 by b. Thereafter, as shown in (C), while rotating the semiconductor wafer 1 by the brush cleaning device 7, the back surface 1b of the semiconductor wafer 1 is cleaned by the brush 9 to remove dirt on the back surface 1b.

The cleaning of the semiconductor wafer 1 by the brush 9 may be performed only on the back surface 1b thereof, but FIG.
As shown in, it may be performed on both the mirror surface 1a and the back surface 1b. In this way, applying the brush on both sides, that is, applying the brush 9 to the mirror surface 1a is
If the brush 9 is applied only to the back surface 1b of the semiconductor wafer 1, the force received from the brush 9 may cause the semiconductor wafer 1 to warp or come off the wafer holder 8. Therefore, in order to avoid it, the force is substantially equal on both sides of the semiconductor wafer 1. Is to join the. Therefore, when there is no risk that the semiconductor wafer 1 will warp or come off from the wafer holder 8, the cleaning by the brush 9 is performed on the back surface 1 of the semiconductor wafer 1.
It should be done only for b.

According to such a method for cleaning a wafer,
Mirror surface cleaning is first performed by jetting the chemical liquid 5a onto the mirror surface (front surface) 1a of the semiconductor wafer 1, and then pure water 5
Since the back surface 1b of the semiconductor wafer 1 is cleaned with the brush 9 after rinsing with b, the dirt on the back surface 1b due to dust, metal, organic matter, etc. can be removed. Therefore, the semiconductor wafer 1 is sent to the next step with its back surface 1b being contaminated, and the mirror surface 1a of itself or another semiconductor wafer 1 is transferred.
It is possible to eliminate the risk of contaminating the mirror surface 1a.

2 (A) and 2 (B) show a loader and an unloader unit for cleaning the semiconductor wafer 1 or for accommodating or discharging the cleaned semiconductor wafer 1, FIG.
Is a loading or unloading elevator, and (B) is a wafer transfer device. Reference numeral 10 denotes an elevator for loading or unloading, which has a structure in which a carrier 11 for accommodating a plurality of semiconductor wafers 1 in a horizontal direction so as to be vertically vertically separated is supported by an elevating table 12. The elevating table is moved up and down by an elevating mechanism 13 including, for example, a rack and a pinion.

Next, the wafer transfer device 4 will be described with reference to FIG. FIG. 2 (B) is a plan view of the transfer device 14 at the top, a side view at the bottom, and a two-dot chain line in the upper right part is a plan view of the state where the arm 15 is retracted. is there. 16 is a claw portion at the tip of the arm 15;
Reference numeral 7 denotes a rotating piece rotatably connected to the base end of the arm 15 at one end, and rotatably connected to one end of another rotating piece 18 at the other end. The other end of the rotating piece 18 is rotatably supported by the moving table 19. Then, the arm 15 moves forward and backward by the expansion and contraction operation by the two rotating pieces 17 and 18.

The semiconductor wafer 1 accommodated in the elevator 10 is removed from the elevator 10 by the forward / backward movement of the arm 15 of the wafer transfer device 14, transferred to the rinsing device 2 etc. by the movement of the moving table 19, and further arm 15 is moved.
It is provided for cleaning by the forward movement of. Then, the cleaned semiconductor wafer 1 is unloaded into the unloading elevator by the wafer transfer device.

FIG. 3 is a perspective view showing the chemical liquid processing apparatus 1a, which is a support base 2 for supporting the semiconductor wafer 1 by vacuum suction.
2, a rotating mechanism (not shown) for rotating the same, and a chemical solution 5a
As described above, the nozzles 6a, 6b and 6c for ejecting

FIG. 4 is a perspective view showing the rinse device in more detail. Reference numeral 20 denotes an ultrasonic wave generator, which sends pure water supplied from a pure water supply pipe 21 to the nozzles 6, 6 and sprays both surfaces of the semiconductor wafer 1 in a spray form from the nozzles 6, 6 for cleaning. The rotating frames 3, 3, 3, ...
Are designed to be movable in the centripetal direction and the centrifugal direction when the wafer is taken in and out so that the semiconductor wafer 1 can be taken in and out.

FIGS. 5A and 5B show the brush cleaning device 7, FIG. 5A being a perspective view and FIG. 5B being a side view.
In the drawing, reference numeral 8 denotes a thin donut-shaped wafer holder for holding the semiconductor wafer 1 in the central portion, which is rotatably held by a holding means (not shown), has outer teeth on its outer peripheral surface, and has pinions on the outer teeth. Twenty-five have been dented. Then, the pinion 25 is rotated by a rotation mechanism (not shown), and the rotational force is transmitted to the wafer holder 8.
Therefore, the semiconductor wafer 1 rotates.

Reference numerals 23 and 23 denote arms that support the brushes 9 and 9 at their tips. The base ends of the arms are rotatably supported by a support piece 25, and the two pairs of arms 23, 23, 23, 23 have tips between them. Holds the two brushes 9, 9. Each arm 23,
The base ends of 23, 23, 23 are supported by the support portion 24. Then, by rotating the arms 23, 23, 23, 23, the brushes 9, 9 come into contact with both front and back surfaces of the semiconductor wafer 1, and the semiconductor wafer 1 is separated from the semiconductor wafer 1 and put in and out of the wafer holder 8. It becomes possible. Then, the brush is cleaned by rotating the wafer 1 with the tip of the brush 9 in contact with the surface of the semiconductor wafer 1.

FIG. 6 is a perspective view showing another example 7a of the brush cleaning device 7. In this example, only the back surface of the semiconductor wafer 1 is brush-cleaned. Reference numeral 22 denotes a wafer support, which supports the semiconductor wafer 1 by vacuum suction and is rotated by a rotation mechanism (not shown). A holding mechanism 23 holds the brush 9, and holds the brush 9 between the tips of the pair of arms 23, 23. The base ends of the arms 23, 23 are rotatably supported by support pieces 24, 24.

When the arms 23, 23 rotate, the brush 9 comes into contact with the mirror surface 1a of the semiconductor wafer 1 on the wafer support 1, or separates from the semiconductor wafer 1 to clean the semiconductor wafer 1 with a brush. It will be in a state where it can be taken in and out. The brush cleaning may be performed while spraying pure water 5b as shown in FIG.

FIGS. 7A to 7K are explanatory views of the cleaning method showing the cleaning method of the wafer shown in FIG. 1 in more detail. First, as shown in (A), the wafer 1 accommodated in the loading elevator 10 is transferred by the wafer transfer device 14 as shown in (B), and the chemical solution processing device 2a is transferred.
Send to. Then, as shown in FIG. 7C, the mirror surface 1a of the semiconductor wafer 1 is chemically cleaned by the chemical processing device 2a.

The semiconductor wafer 1 after the chemical cleaning is shown in FIG.
As shown in (D), the wafer transfer device 14 transfers the wafer to the rinsing device 2b. Then, as shown in FIG. 7 (E), both main surfaces 1 of the semiconductor wafer 1 are deionized with pure water in the rinsing device 2b.
Rinse a and 1b. Semiconductor wafer 1 after rinsing
Is transferred to the brush cleaning device 7 by the wafer transfer device 14 as shown in FIG. Then, as shown in FIG. 7G, the brush cleaning device 7 brush-cleans the mirror surface and the back surface of the semiconductor wafer 1. By this brush cleaning, the dirt on the back surface of the semiconductor wafer 1 can be removed.

Next, the semiconductor wafer 1 after brush cleaning is completed.
Is transferred to the rinsing device 2b by the wafer transfer device 14 as shown in FIG. 7 (H). Then, as shown in FIG. 7 (I), the rinse device 2b again rinses with pure water, and the semiconductor wafer 1 after the re-rinsing is transferred by the wafer transfer device 17 as shown in FIG. It is stored in the unloading elevator 10 as shown in (K).

A chemical treatment device having the same structure as the rinse device 1b shown in FIG. 4 is used to hold the semiconductor wafer 1 with its back surface 1b facing upward, and to hold the semiconductor wafer 1 on the downward mirror surface 1a. On the other hand, the chemical solution 5a may be jetted from the lower side by the nozzle 6 to perform the chemical solution treatment.

In this case, the semiconductor wafer 1 is conveyed with the back surface 1b facing upward. Therefore, the brush cleaning may be performed by a method of cleaning only the upper surface 1b of the semiconductor wafer 1 with the brush 9 using a brush cleaning device as shown in FIG. Further, the present invention can be implemented in various modes, such that the chemical solution treatment and the rinse may be performed in the same chamber.

[0029]

The wafer cleaning method of the present invention is characterized in that after cleaning the front surface of the wafer with a liquid, at least the rear surface of the wafer is cleaned with a brush. Therefore,
According to the wafer cleaning method of the present invention, after cleaning the front surface of the wafer with the liquid, at least the back surface of the wafer is cleaned with a brush, so that dirt on the back surface due to dust, metal, organic matter, etc. can be removed. Therefore, it is possible to eliminate the risk that the semiconductor wafer will be sent to the next step with its back surface contaminated and will contaminate itself or other semiconductor wafers.

[Brief description of drawings]

1A to 1C are schematic explanatory views sequentially showing the outline of one embodiment of a wafer cleaning method of the present invention.

2A and 2B are configuration diagrams of an example of a loader and an unloader unit used for carrying out the wafer cleaning method of the present invention. FIG. 2A shows an elevator, and FIG. 2B shows a wafer transfer device. ..

FIG. 3 is a perspective view showing an example of a chemical liquid processing apparatus used for carrying out the wafer cleaning method of the present invention.

FIG. 4 is a perspective view showing an example of a rinse device used for carrying out the wafer cleaning method of the present invention.

5A and 5B show a brush cleaning apparatus used for carrying out the wafer cleaning method of the present invention. FIG. 5A is a perspective view and FIG. 5B is a side view.

FIG. 6 is a perspective view showing another example of the brush cleaning apparatus used for carrying out the wafer cleaning method of the present invention.

7 (A) to 7 (K) are explanatory views for specifically explaining the cleaning method of the wafer shown in FIG. 1 in order.

FIG. 8 is a diagram showing one conventional example of a wafer cleaning method.

FIG. 9 is a diagram showing another conventional example of a wafer cleaning method.

[Explanation of symbols]

 1 wafer 1a front surface (mirror surface) 1b back surface 5a, 5b liquid 9 brush

Claims (1)

Claim: What is claimed is: 1. A method of cleaning a wafer, which comprises cleaning at least a back surface of a wafer with a brush after cleaning the front surface of the wafer with a liquid.