JP2009289779A - Silicon wafer cleaning method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning method and a cleaning device that prevent the device from becoming huge excessively even in the case of a silicon wafer having an increased aperture, also reduce the amount of used chemical with respect to the aperture. <P>SOLUTION: By the cleaning method, a silicon wafer is moved and washed in a cleaning liquid of a cleaning tank. On a down slope where a stream of water or an air current is jetted out of one portion of the surface being provided in the cleaning tank, the silicon wafer is moved by free fall without being brought into contact with the slope. On an up slope following the down slope provided in the cleaning tank, the silicon wafer moved by free fall is pulled and moved without being brought into contact with an inclined surface for cleaning during the travel. The silicon wafer cleaning device includes the cleaning tank where the bottom section has a down slope from an inlet side and an up slope toward an outlet side. The down slope has a jet for jetting out a stream of water and/or bubbles, the up slope has a means for pulling and moving the silicon wafer along the inclined surface, and the silicon wafer is cleaned in the cleaning liquid while the silicon wafer is moved on the down and up slopes. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a silicon wafer cleaning method and a cleaning apparatus. The cleaning method and the cleaning apparatus of the present invention are particularly suitable for cleaning a large-diameter silicon wafer substrate.

  The size of a silicon wafer cut out from a silicon single crystal has become larger in a cycle of about 10 years. In device manufacturers, it is desired to increase device manufacturing efficiency by increasing the size of silicon wafers. Under such circumstances, it is planned to manufacture a silicon wafer of about 450 mm having a diameter of about 1.5 times the current diameter of 300 mm in the near future.

Conventionally used silicon wafer cleaning techniques include a carrier batch cleaning system, a carrierless batch cleaning system, and a rotating single wafer cleaning system (Non-Patent Documents 1 and 2).
“Ultra-precision wafer surface control technology”, Science Forum, Inc. (Chapter 9: Cleaning Technology, Published February 28, 2000) "Cleaning technology for the new silicon wafer surface", Realize Science and Technology Center Co., Ltd. (May 28, 2000, Chapter 6: Silicon wafer cleaning technology)

  However, if the conventional batch cleaning method is applied to a silicon wafer with a large diameter as it is, the apparatus becomes enormous and an increase in the amount of chemicals used due to the enlargement of the processing tank is essential, which inevitably causes cost problems. To do. Therefore, there is a need for a cleaning method and apparatus that take into account the excessive enlargement of the apparatus and the reduction in the amount of chemicals used.

  In addition, as the substrate size increases, the dimensions of various processing equipment must be increased, and from the viewpoint of effective use of the clean room, a technology that can simultaneously carry and clean wafers is necessary. Then, the present inventors considered.

  Accordingly, an object of the present invention is to provide a cleaning method and apparatus capable of reducing the amount of chemical solution to be used for the diameter of the apparatus without excessively enlarging the apparatus even for a silicon wafer having a large diameter of about 450 mm. It is to provide. In addition, an object of the present invention is to provide an apparatus capable of simultaneously carrying and cleaning a silicon wafer between various processing process apparatuses.

  In order to solve the above-mentioned problems and achieve the object of the present invention, the present inventors have variously studied, providing a down slope and an up slope in the cleaning tank, moving the wafer on these slopes, and during this movement The present invention was completed by finding that the wafer cleaning and the wafer transfer can be made compatible by cleaning the wafer.

A first aspect of the present invention is a method for cleaning a silicon wafer while moving it in a cleaning liquid in a cleaning tank,
Provided in the washing tank, the down slope where water flow or air current is ejected from at least a part of the surface is moved by free fall without bringing the silicon wafer into contact with the slope,
Next, the silicon wafer moved by the free fall is pulled to move without contacting the inclined surface, which is provided in the cleaning tank and may be continuous with the downward inclined surface,
The silicon wafer cleaning method is characterized in that cleaning is performed during the movement.

In the second aspect of the present invention, the bottom portion has a down slope from the inlet side and an up slope toward the outlet side, and has or does not have a flat surface between the down slope and the up slope. A silicon wafer cleaning apparatus comprising:
The descending slope has a water outlet and / or a blowout port for blowing out bubbles,
The ascending slope has means for pulling and moving the silicon wafer along the slope;
An apparatus for cleaning a silicon wafer with a cleaning liquid in a cleaning tank while moving the down slope and the up slope.

  According to the present invention, since wafer transfer is carried out in a water stream, it becomes possible to carry out wafer cleaning processing simultaneously with the transfer, and therefore there is no need for buffers or stockers for retaining workpieces before and after various processing processes. Cleaning treatment is possible. It is possible to provide a cleaning method and apparatus that do not require external driving means (rollers, belts, robots, etc.) for wafer conveyance during cleaning.

  The silicon wafer cleaning method of the present invention is a method of cleaning a silicon wafer while moving it in a cleaning solution in a cleaning tank. In this method, a down slope provided with water or airflow from at least a part of the surface provided in the cleaning tank is moved by free fall without bringing the silicon wafer into contact with the slope, and then in the cleaning tank. The ascending slope, which may be continuous with the descending slope, is moved by pulling the silicon wafer moved by the free fall without contacting the slope, and cleaned during the movement. And

  This silicon wafer cleaning method of the present invention can be implemented, for example, by the following silicon wafer cleaning apparatus of the present invention. The silicon wafer cleaning apparatus of the present invention has a bottom having a downward slope from the inlet side and an upward slope toward the outlet side, and a cleaning tank having or not having a flat surface between the downward slope and the upward slope. A silicon wafer cleaning apparatus, wherein the down slope has a blow-out port for blowing out water flow and / or bubbles, and the up slope has means for pulling and moving the silicon wafer along the slope. It is. This apparatus is an apparatus for cleaning a silicon wafer with a cleaning liquid in a cleaning tank while moving the down slope and the up slope.

  The silicon wafer cleaning apparatus of the present invention will be described with reference to the schematic sectional view of the cleaning apparatus of the present invention shown in FIG.

  The cleaning apparatus 1 has a cleaning tank 10 and a bottom 11 of the cleaning tank 10 having a descending slope 20 from the entrance side 12 and an ascending slope 21 toward the exit side 13, and between the descending slope 20 and the ascending slope 21. May or may not have a flat surface. The apparatus shown in FIG. 1 has a flat surface.

  The cleaning tank 10 is for holding an aqueous solution for cleaning a silicon wafer, such as high pure water, ultra high pure water, or a detergent-containing liquid. Examples of the material of the cleaning tank include quartz, Teflon, and Pyrex glass.

  The planar shape of the cleaning tank 10 is a belt shape. The width of the cleaning tank 10 having a strip shape in the plan view is at least larger than the diameter of the silicon wafer to be cleaned, preferably 1.1 of the diameter of the silicon wafer to be cleaned, when sequentially cleaning one silicon wafer to be cleaned. It can range from 2 to 2 times. Further, two silicon wafers to be cleaned can be sequentially cleaned in parallel. In this case, the width of the cleaning tank 10 is, for example, 1.5 to 2.5 times the diameter of the silicon wafer to be cleaned. Can range. When two silicon wafers to be cleaned are cleaned in parallel, the two silicon wafers to be cleaned can be simultaneously loaded into the cleaning tank 10. Alternatively, the two cleaning silicon wafers can be alternately carried into the cleaning tank 10 so that the transport lanes partially overlap each other. In this case, the width of the cleaning tank 10 may be less than twice the diameter of the silicon wafer to be cleaned, for example. Similarly, three or more silicon wafers to be cleaned can be simultaneously loaded into the cleaning tank 10. Or it can also be carried in to the washing tank 10 sequentially so that the conveyance lanes of three silicon wafers to be cleaned may partially overlap.

  The down slope 20 has a blowout port for blowing out water flow and / or bubbles. The silicon wafer moves on a downward slope from which a water flow or an air current is ejected by free fall without contacting the slope. The down slope 20 can be comprised with the perforated plate, and can blow off a water flow and / or a bubble through the hole of a perforated plate. The water flow and / or bubbles blown from the down slope give the silicon wafer that falls freely while receiving buoyancy in the cleaning solution to suppress contact with the slope, but the slope due to free fall. Allow movement above.

  The water flow and the bubbles may be present alone or together, and the amount of blowout can be appropriately determined from an amount that allows the movement of the silicon wafer on the slope due to free fall, while suppressing the contact of the silicon wafer with the slope.

  The angle of the down slope can be, for example, in the range of 10 to 45 °. If the angle of the descending slope is large, free fall is easy, but it is difficult to suppress contact with the slope, and if the angle of the descending slope is small, free fall is weak, but contact with the slope is easy. The angle is appropriately determined in consideration of the degree of free fall and ease of contact with the slope.

  If there is a flat surface, the silicon wafer moved on the down slope 20 by free fall moves further on the flat face. After moving the flat face, the silicon wafer reaches the up slope 21. If there is no flat face, the silicon wafer moves on the up slope 21. To do. There are no particular restrictions on the method and means for moving the flat surface. For example, the flat surface is also composed of a perforated plate in the same manner as the descending slope 20, and water flow and / or bubbles are blown out through the holes of the perforated plate. Thus, the silicon wafer can be suspended in the cleaning liquid, thereby suppressing contact with the flat surface of the silicon wafer, and towed and moved by the same pulling means as provided on the upslope 21.

  The ascending slope 21 has means for pulling and moving the silicon wafer along the slope. The means 30 for pulling and moving may be, for example, an arm having a projection or the like that is pulled at the rear part of the silicon wafer at the tip, and a robot arm having a drive unit outside the cleaning tank.

  The ascending slope 21 is preferably made of a perforated plate, like the descending slope 20, and the point that water flow or air flow is ejected from at least a part of the surface suppresses contact with the slope of the silicon wafer. Is preferable. The angle of the up slope can be in the range of 10-45 °. If the angle of the ascending slope is large, the traction movement distance is shortened and the contact with the slope is easily suppressed. On the other hand, if the angle of the ascending slope is small, the traction movement distance becomes long (the flat area of the device also becomes large), and it becomes relatively difficult to suppress contact with the slope. The angle is appropriately determined in consideration of the pulling movement distance and ease of contact with the slope.

  The angle of the descending slope 20 and the angle 21 of the ascending slope may be the same or different.

  FIG. 1 shows an embodiment in which three washing tanks are connected. In this manner, a plurality of cleaning tanks can be sequentially provided to continuously clean the silicon wafer SW. The silicon wafer SW can be carried into the cleaning tank 10 by using existing means such as a robot arm as described above. A plurality of cleaning tanks 10 are provided adjacent to each other, and a roller is provided at the boundary between adjacent cleaning tanks 10 so that the wafer moved to the upper part of the tank by the traction means 30 is thrown into the next tank in accordance with the boundary part rollers. Thereafter, continuous wet processing of the wafer can be performed by the same processing. Although three cleaning tanks are shown in FIG. 1, four or more cleaning tanks may be provided in succession and cleaned sequentially with a cleaning liquid (cleaning liquid).

  The silicon wafer SW to be cleaned may be made of a semiconductor other than a silicon wafer, and the size can be applied to a wafer of any diameter such as φ200 mm, φ300 mm, and φ450 mm. However, the method and apparatus of the present invention are particularly suitable for cleaning large silicon wafers having a diameter in the range of 400 to 650 mm.

  Hereinafter, the present invention will be described based on examples.

  Using a silicon wafer cleaning apparatus in which a plurality of oblique jet nozzles are provided in parallel at the lower part of the cleaning tank shown in FIG. 1, a φ450 mm silicon wafer placed on the water stream formed by spraying a positively pressurized water stream with a pump or the like Washed while transporting.

  The size of each cleaning tank is 500 mm wide × 1000 mm long × maximum depth of the chemical solution reservoir 300 mm.

  The angle of the descending slope provided in the cleaning tank is 30 °, and the angle of the ascending slope is 30 °. The perforated plate that constitutes the down slope is made of PTFE perforated plate with a pore diameter of 1 mm, and a water flow is injected from this perforated plate at a flow rate of 1 L / min, so that the down slope and the silicon wafer are in contact with each other. Was suppressed.

  Useful in the field of silicon wafer production.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional explanatory view of a silicon wafer cleaning apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Washing tank 20 Downhill slope 21 Uphill slope 30 Tow moving means

Claims (10)

A method of cleaning while moving a silicon wafer in a cleaning solution in a cleaning tank,
Provided in the washing tank, the down slope where water flow or air current is ejected from at least a part of the surface is moved by free fall without bringing the silicon wafer into contact with the slope,
Next, the silicon wafer moved by the free fall is pulled to move without contacting the inclined surface, which is provided in the cleaning tank and may be continuous with the downward inclined surface,
A silicon wafer cleaning method, wherein cleaning is performed during the movement. The angle of the descending slope is in the range of 10 to 45 °, the angle of the ascending slope is in the range of 10 to 45 °, and the angle of the descending slope and the angle of the ascending slope may be the same or different. Cleaning method. The cleaning method according to claim 1, wherein a water flow or an air flow is ejected from at least a part of the surface of the ascending slope. The method according to any one of claims 1 to 3, wherein the water stream or the air stream ejected from the slope is blown out from the surface of the porous plate constituting the slope. The method according to claim 1, wherein the cleaning tank has a flat surface between a descending slope and an ascending slope, and a water flow or an air current is ejected from at least a part of the surface of the flat surface. The method according to any one of claims 1 to 5, wherein the diameter of the silicon wafer to be cleaned is in the range of 400 to 650 mm. A silicon wafer cleaning apparatus, comprising a cleaning tank having a bottom slope from the entrance side and an ascending slope toward the exit side, and having or not having a flat surface between the descending slope and the ascending slope. And
The descending slope has a water outlet and / or a blowout port for blowing out bubbles,
The ascending slope has means for pulling and moving the silicon wafer along the slope;
An apparatus for cleaning a silicon wafer with a cleaning liquid in a cleaning tank while moving the down slope and the up slope. The cleaning apparatus according to claim 7, wherein the ascending slope and / or the flat surface has a blowout port for blowing out water flow and / or bubbles. The cleaning apparatus according to claim 7 or 8, wherein the down slope, the up slope and / or the flat surface is formed of a perforated plate. The angle of the descending slope is in the range of 10 to 45 °, the angle of the ascending slope is in the range of 10 to 45 °, and the angle of the descending slope and the angle of the ascending slope may be the same or different. The cleaning apparatus according to any one of the above.