JPH0745576A - Wafer cleaning device and cleaning of wafer - Google Patents

Abstract

PURPOSE:To make it possible to remove fully contamination of the surface of a wafer by a method wherein a wafer cleaning device is provided with a wafer rotating machine for rotating the wafer in a state that the wafer is held in a cleaning tank for cleaning the wafer and is provided with cleaning liquid feed pipes for feeding a cleaning liquid in the cleaning tank. CONSTITUTION:A wafer cleaning device 30 is constituted of a cleaning tank 40, in which a cleaning liquid is stored, and a wafer rotating machine 60 for rotating a wafer. The tank 40 is provided with cleaning liquid feed pipes 42 for feeding the cleaning liquid. Moreover, the tank 40 is constituted into such a structure that a plurality of cleaning liquid discharge pipes 44 and 46 are provided at both of the bottom and upper part of the tank 40, dusts having a small specific gravity are discharged through the pipes 46 provided at the upper part and dusts having a large specific gravity are discharged through the pipes 44 provided at the bottom. As the wafer is cleaned while being rotated in the cleaning liquid, the dusts, such as the silicon dusts, removed once from the wafer surface can be prevented from springing back and adhering on the wafer surface. Moreover, in the case where the cleaning liquid jets in the direction to oppose to the rotation of the wafer the cleaning effect of the wafer is more improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer cleaning apparatus and a wafer cleaning method, and more particularly to a wafer cleaning apparatus and a wafer cleaning method suitable for cleaning a wafer immediately after dicing.

[0002]

2. Description of the Related Art A large number of chips are arranged side by side vertically and horizontally in a wafer, and a gap called a scribe line is formed between adjacent chips. In dicing to separate the wafer into individual chips, the wafer is attached to a vinyl sheet with an adhesive, and it is cut along the scribe line with a blade that rotates at high speed while applying a cooling liquid of about 25 ° C Are separated from each other. Since the vinyl sheet is not cut, it is possible to obtain a large number of chips separated from each other while being stuck to the vinyl sheet. During dicing, dust such as silicon chips is generated and the wafer is contaminated. However, the cleaning liquid applied to the wafer during the cutting of the wafer cannot remove the contamination of the wafer. For this reason,
The diced wafer is washed immediately after dicing.

As a method for cleaning the wafer immediately after the dicing, the wafer which has been diced is sucked by a Bernoulli chuck and automatically transferred to a cleaning device, and the cleaning device rotates the wafer at a high speed and sprays cleaning water on the surface. A method of doing so is known (see Japanese Patent Publication No. 62-6344). In this conventional cleaning method, the wafer is transferred to the cleaning device by automatic transfer without holding the wafer with tweezers or the like, so that chipping or the like of the wafer can be prevented, and dirt such as silicon debris attached to the wafer can be prevented. It can be reduced by spraying wash water.

[0004]

However, when cleaning water is sprayed on a wafer that is rotating at a high speed, a large amount of atomized steam is generated in the vicinity of the wafer, so that a large-capacity exhaust duct and scattering of steam are prevented. A shatterproof wall is required around the cleaning device. Further, since the wafer is rotating at a high speed, there is a possibility that silicon debris or the like spattered by the cleaning water sprayed on the wafer surface hits the scattering prevention wall and bounces back and adheres to the wafer surface again. Therefore, there is a problem in that it may not be possible to sufficiently remove silicon debris and the like on the wafer surface.

In view of the above circumstances, it is an object of the present invention to provide a wafer cleaning apparatus and a wafer cleaning method capable of sufficiently removing dirt on the wafer surface.

[0006]

A wafer cleaning apparatus for achieving the above object comprises a cleaning tank in which a cleaning liquid for cleaning a wafer is stored, and a wafer held in the cleaning tank for cleaning the wafer. A wafer rotating machine for rotating the wafer is provided. Here, it is preferable that a cleaning liquid supply pipe for supplying the cleaning liquid to the cleaning tank is provided, and further a cleaning liquid discharge pipe is provided at both a bottom portion and an upper portion of the cleaning tank. Further, it is preferable that the cleaning liquid supply pipe is configured to eject the cleaning liquid in a direction opposite to the rotation of the wafer. Further, it is preferable that the wafer rotating machine includes a rotation shaft that rotates the wafer and revolves around a predetermined rotation shaft that is separated from the rotation region of the wafer. Furthermore, it is preferable to provide a specific resistance measuring device for measuring the specific resistance of the cleaning liquid in the cleaning tank in the cleaning tank.

Further, in a wafer cleaning method for achieving the above object, the wafer is cleaned by rotating the wafer in a cleaning solution stored in a cleaning tank and ejecting the cleaning solution in a direction opposite to the rotation of the wafer. It is characterized by that. Here, it is preferable to provide a CO ₂ bubble generator below the cleaning tank and supply the CO ₂ bubble to the cleaning liquid from the bottom of the cleaning tank. Further, it is preferable to rotate the wafer in a tilted state. Furthermore, it is preferable that the temperature of the cleaning liquid is 30 ° C. or higher for cleaning.

[0008]

Since the wafer cleaning apparatus of the present invention comprises the cleaning tank for storing the cleaning liquid and the wafer rotating machine for rotating the wafer in the cleaning tank, the wafer is cleaned while being rotated in the cleaning liquid. It Therefore, it is possible to prevent dust such as silicon dust once removed from the wafer surface from bouncing back and adhering again to the wafer surface, and dust can be sufficiently removed.

If a cleaning liquid supply pipe for supplying the cleaning liquid to the cleaning tank is provided and further a cleaning liquid discharge pipe is provided at both the bottom and the upper portion of the cleaning tank, dust with a small specific gravity is discharged from the upper cleaning liquid discharge pipe. While the dust having a large specific gravity is discharged from the bottom cleaning liquid discharge pipe, a new cleaning liquid can be supplied from the cleaning liquid supply pipe, so that the cleaning effect is improved and the dust can be removed more sufficiently.

Further, when the cleaning liquid supply pipe is constructed so as to eject the cleaning liquid in the direction opposite to the rotation of the wafer, the contact resistance between the wafer surface and the cleaning liquid increases and dust is easily separated, so that the cleaning effect is further improved. To do. Furthermore, when the wafer rotating machine is equipped with a rotating shaft that rotates the wafer on its own axis and revolves around a predetermined rotating axis away from the rotation area of the wafer, the cleaning liquid is applied to the wafer surface from various directions to further enhance the cleaning effect. improves.

Furthermore, when a specific resistance measuring device for measuring the specific resistance of the cleaning liquid in the cleaning tank is provided in the cleaning tank, the contamination of the cleaning liquid can be measured by measuring the specific resistance of the cleaning liquid, and the specific resistance is small. It can be judged that the wafer has been sufficiently cleaned. According to the wafer cleaning method of the present invention, since the wafer is cleaned in the cleaning liquid jetted in the direction opposite to the rotation of the wafer, dust can be sufficiently removed.

When CO ₂ bubbles are supplied to the cleaning liquid from the bottom of the cleaning tank, the effect of preventing electrostatic breakdown can be sufficiently exerted. Further, when the wafer is rotated in a tilted state, the contact resistance between the wafer surface and the cleaning liquid increases, and the dust easily separates, so that the cleaning effect is further improved. Furthermore, when the temperature of the cleaning liquid is set to 30 ° C. or higher and a large number of chips separated from each other are attached to the vinyl sheet, the vinyl sheet expands to widen the gap between the chips, so Dirt can be removed well and the cleaning area can be expanded.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the wafer cleaning apparatus and wafer cleaning method of the present invention will be described below. Here, an example in which the present invention is applied to cleaning a wafer immediately after dicing is shown, FIG. 1 is a plan view showing a state in which a dicing device and a wafer cleaning device are arranged, and FIG. 2 shows a wafer fixed to a vinyl sheet. (A) is a plan view and (b) is a sectional view taken along line AA of (a).

First, an outline of wafer dicing and cleaning will be described. The wafer 10 is a vinyl sheet 1 attached to a stainless frame 12 having a thickness of 2 to 3 mm.
4 is fixed to the central portion of the loader 4 with an adhesive material, and in this fixed state, the loader 1 is loaded into a wafer cassette (not shown).
Set to 6. The wafer 10 set in the wafer cassette is automatically transferred to the first stage 18 where dicing is performed. At this first stage 18, while the cooling liquid of about 25 ° C. is supplied to the wafer 10, the wafer 10 is diced by the high-speed rotating blade. Is done. The diced wafer 10 is sucked by a Bernoulli chuck and automatically conveyed to the second stage 20.
At 0, the wafer cleaning device 30 cleans and dries the wafer. Wafers that have been cleaned and dried are unloader 2
Moved to 2.

Next, referring to FIG. 3, a wafer cleaning device 30
The structure of is explained. FIG. 3 is an explanatory diagram showing a schematic configuration of the wafer cleaning apparatus. The wafer cleaning device 30 includes a cleaning tank 40 that stores a cleaning liquid, and a wafer rotator 60 that rotates the wafer while holding the wafer. Cleaning liquid supply pipe 4 for supplying the cleaning liquid to the cleaning tank 40
2 is provided, and the cleaning liquid is ejected from the cleaning liquid supply pipe 42 in a direction opposite to the rotation of the wafer. Further, a plurality of cleaning liquid discharge pipes 44 and 46 are provided at both the bottom and the upper part of the cleaning tank 40, and dust having a small specific gravity is discharged from the cleaning liquid discharge pipe 46 at the upper part, and dust having a large specific gravity is discharged to the cleaning liquid discharge pipe at the bottom. It is configured to be discharged from 44. A damper 48 is provided below the cleaning liquid discharge pipe 44, and the discharge amount of the cleaning liquid is adjusted by adjusting the damper 48. A CO ₂ gas supply device (not shown) is provided below the cleaning tank 40, and the gas supply pipe 5
The cleaning liquid is supplied from the bottom of the cleaning tank 40 via 0. Further, the cleaning tank 40 is provided with a specific resistance measuring device 52 for measuring the specific resistance of the cleaning liquid, and is configured so that the dirt of the cleaning liquid can be measured by measuring the specific resistance of the cleaning liquid.

The wafer rotating machine 60 includes a wafer holder 62 for holding a wafer by utilizing vacuum, and the wafer holder 6
It is configured to include a rotating shaft 64 that supports and rotates the device 2. A large number of holes (not shown) are formed on the wafer holding surface of the wafer holding portion 62, and these holes are connected to a vacuum device (not shown) via a vacuum pipe 66. The rotary shaft 64 is configured to be expandable / contractible by a rotary shaft expander / retractor 68, and when the wafer transferred from the first stage 18 (see FIG. 1) is received, the rotary shaft 64 extends beyond the cleaning liquid surface to a position indicated by a broken line. The wafer holder 62 is raised, and during cleaning, the wafer holder 62 is lowered into the cleaning liquid. The rotation shaft 64 is driven by a motor 70 to rotate the wafer held by the wafer holding portion 62 and revolve around a predetermined rotation shaft separated from the rotation region of the wafer to rotate the wafer in a tilted state. It is also configured to be able to.

Next, a process of cleaning the wafer diced by the first stage 18 (see FIG. 1) by the wafer cleaning device 30 will be described. The wafer 10 that has been diced by the first stage 18 (see FIG. 1) is transferred to the wafer holding section 62 at a position higher than the cleaning liquid surface and held by the wafer holding section 62 in the state shown in FIG. . Wafer 1
The wafer holding unit 62 holding 0 moves down into the cleaning liquid as the rotating shaft 64 moves down, whereby the wafer 10 is immersed in the cleaning liquid. The wafer holder 62 rotates in the cleaning liquid and revolves around a predetermined axis, while the cleaning liquid supply pipe 4
The cleaning liquid is ejected from 2 in a direction opposite to the rotation of the wafer, thereby increasing the contact resistance between the wafer surface and the cleaning liquid and contacting the wafer surface from various directions, so that the wafer is sufficiently cleaned. Moreover, the temperature of the cleaning liquid is about 30 ° C. Therefore, the vinyl sheet 14
(See FIG. 2) expands to widen the gap between the chips adjacent to each other, so that stains around the chips can be removed well and the cleaning region can be expanded. Furthermore, by supplying CO ₂ gas to the cleaning liquid from the bottom of the cleaning tank 40 via the CO ₂ gas supply pipe 50 during cleaning of the wafer, electrostatic damage of the wafer can be prevented. Whether or not the cleaning of the wafer is completed can be judged by measuring the specific resistance of the cleaning liquid with the specific resistance measuring device 52. For example, the specific resistance is 1 MΩ.
When it reaches cm, the cleaning is finished. As a result, the plurality of wafers can be cleaned so as to have a uniform cleanliness. After the cleaning of the wafer is completed, the cleaning liquid is discharged and the wafer holding unit 62 is rotated at a high speed to dry the wafer.

In the above-mentioned example, when the wafer is transferred to the second stage, the wafer holding part is raised above the cleaning liquid surface, but it may be transferred to the second stage without the cleaning liquid and then the cleaning liquid may be supplied. .

[0019]

As described above, according to the wafer cleaning apparatus and the wafer cleaning method of the present invention, since the wafer is rotated and cleaned in the cleaning liquid stored in the cleaning tank, the dust can be sufficiently removed. The cleaning effect is improved.

[Brief description of drawings]

FIG. 1 is a plan view showing a state in which a dicing device and a wafer cleaning device are arranged.

FIG. 2 shows a wafer secured to a vinyl sheet,
(A) is a plan view and (b) is a sectional view taken along line AA of (a).

FIG. 3 is an explanatory diagram showing a schematic configuration of an embodiment of a wafer cleaning apparatus of the present invention.

[Explanation of symbols]

30 Wafer Cleaning Device 40 Cleaning Tank 42 Cleaning Liquid Supply Pipes 44, 46 Cleaning Liquid Discharge Pipe 50 CO ₂ Gas Supply Pipe 52 Resistivity Measuring Device 60 Wafer Rotating Machine 62 Wafer Holding Unit 64 Rotating Shaft

Claims (5)

[Claims] 1. A wafer cleaning device, comprising: a cleaning tank for storing a cleaning liquid for cleaning a wafer; and a wafer rotator for rotating the wafer while holding the wafer in the cleaning tank. apparatus. 2. The cleaning tank is provided with a cleaning solution supply pipe for supplying a cleaning solution to the cleaning tank and a cleaning solution discharge pipe provided at both a bottom portion and an upper portion of the cleaning tank. The wafer cleaning apparatus described. 3. The wafer cleaning apparatus according to claim 2, wherein the cleaning liquid supply pipe ejects the cleaning liquid in a direction opposed to the rotation of the wafer. 4. The wafer cleaning apparatus according to claim 1, wherein the wafer rotating machine includes a rotation shaft that rotates the wafer and revolves around a predetermined rotation shaft separated from a rotation region of the wafer. apparatus. 5. A wafer cleaning method comprising rotating a wafer in a cleaning liquid stored in a cleaning tank and ejecting the cleaning liquid in a direction opposite to the rotation of the wafer to clean the wafer.