JPS62162467A - Polishing device for wafer - Google Patents

Abstract

PURPOSE:To improve working environment, to make the jog safety, to increase working efficiency, and to increase reliability of the product by arranging a chuck which fixes a wafer polishing roller, and a supply unit of polishing solution obtained by dispersing abrasive gain in an amine aqueous solution. CONSTITUTION:A wafer W whose surface was ground with a triaxial vertical grinding attachment is transferred onto a vacuum chuck 5 of a polishing unit 1 with a vacuum chuck and sucked thereon. The vacuum chuck 5 starts rotating, and a polishing roller 9 comes down with it rotated, and its circumference comes in contact with the polishing surface S of the wafer W, and a polishing solution drops from a nozzle 13 to polish the surface. After completing the polishing, the polishing roller comes up, and the vacuum chuck stops its rotation, and the polished wafer W is taken out from the vacuum chuck 5 with the vacuum chuck and fed to the next process. Thereby, a job is made safety, no harmful gas evolves, and unnecessary chemical change is not given. Therefore, the reliability of a semiconductor is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a wafer polishing apparatus for finishing the surface of a wafer such as silicon.

(b) Conventional technology In general, for example, a semiconductor silicon wafer is finished by slicing a silicon crystal and then grinding the surface to a predetermined thickness using a grinding device.
Following this grinding, a chemical treatment using a strong acid was performed to obtain a predetermined surface roughness (0.04'±0.02' (maximum height, unit of μm, same hereinafter)).

As an example of the above-mentioned grinding device, a three-axis vertical grinding device shown in FIG. 2 is known. This three-axis vertical grinding device includes three grindstones that are rotatably driven on a rotary table that can suction and support a wafer. Then, the rotary table was rotated at a low speed, and the wafer surface was first ground with a round-sized grindstone, followed by a medium-sized grindstone, and then a fine-sized grindstone.

(c) Problems to be solved by the invention In the conventional wafer surface finishing method described above, chemical treatment using strong acid was essential, which not only posed a danger to the wafer surface finishing work but also generated harmful gases during the work. This method has the disadvantage of requiring large-scale equipment, such as a hazardous gas treatment device to prevent air pollution, and the above treatment must be performed as a separate process, resulting in a significant decrease in work efficiency and yield. Ta.

Furthermore, since the chemical reaction caused by strong acids is powerful, there is a problem in that the wafers are subjected to more chemical changes than necessary, which deteriorates the reliability of semiconductor products manufactured from these wafers.

Therefore, efforts are being made to achieve the required surface roughness only by grinding, and various changes have been made to the grain size of the diamond abrasive grains that make up the grinding wheel, the hardness of the diamond bonding agent that binds the diamond abrasive grains, etc. However, the limit of surface roughness due to grinding with fixed abrasive grains of the whetstone was 0.4" ± 0.2'. With this surface roughness (0.4' ± 0.2'), In the bonding process, when bonding the chips of the scribed wafer to a lead frame or the like, there was an inconvenience that the fusion rate decreased.

The present invention has been made in view of the above-mentioned disadvantages, and an object of the present invention is to provide a wafer polishing apparatus that can obtain a surface roughness equivalent to that obtained by chemical processing using strong acids.

(d) Means for Solving the Problems As a means for solving the above-mentioned disadvantages, the wafer polishing apparatus of the present invention employs the following configuration.

(a chuck that attaches the Al wafer and is driven to rotate; (b) a polishing roller that rotates while contacting the processing surface of the wafer; (C) a polishing liquid supply means that supplies polishing liquid to the processing surface of the wafer.

(E) Function The wafer polishing device of the present invention supplies a polishing liquid in which abrasive grains made of silica powder or the like are dispersed to the processing surface of a rotating wafer, and also brings polygingerol made of cloth, leather, etc. into rotational contact. As a result of polishing the wafer processed surface, the wafer processed surface has a surface roughness of 0.04" ±0.
．． It is possible to process it to a mirror surface of 02".

In addition, methylamine (CH3NH,
), amine compounds (R-NH,, RR"-NH, RR'R"-N, R, R
', R' are hydrocarbon residues) If you use an aqueous solution with abrasive particles dispersed in it, the aqueous solution will dissolve silicon (St), gallium arsenide (GaAs), etc. wafers without contaminating them with metal ions. Due to the synergistic effect with the polishing effect of free abrasive grains in the polishing solution, the surface roughness is improved.At this time, the aqueous solution does not react with metals other than aluminum. It is not necessary to provide the wafer polishing apparatus with any special means (for example, coating) for preventing reaction with the aqueous solution.

(F) Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a partially cutaway perspective view of a wafer polishing apparatus (hereinafter simply referred to as polishing apparatus) 1 according to an embodiment of the present invention. The polychip device 1 has a motor (
A spindle 4 is attached to the upper end of a rotating shaft 3 that projects upward from a base 2 that has a built-in rotational drive means such as (not shown),
Furthermore, a vacuum chuck 5 connected to a vacuum source (not shown) is provided on the spindle 4.

A polishing roller 9 made of a viscoelastic material such as chamois leather or cloth is provided above the vacuum chuck 5 so as to be movable up and down. This polishing roller 9 is driven by a driving means 11 such as a motor.
It is connected to the shaft IO by a shaft IO and is rotationally driven. At this time, the rotation axis P of the polishing roller 9 is parallel to the top surface of the vacuum chuck 5, and the outer peripheral surface of the polishing roller 9 is
It comes into contact with the processing surface S of the wafer W which is suction-supported on the upper surface of the vacuum chuck 5.

Further, a nozzle 13 extending from the side is opened above the vacuum chuck 5, and drops a polycinder liquid onto the processing surface S of the wafer W suction-supported by the vacuum chuck 5.

The base end of the nozzle 13 is connected to a pump (not shown), etc.
A polishing agent liquid is supplied at a flow rate that matches the polishing conditions.

As a polishing liquid, fine powder such as silica (SiO□) is mixed and dispersed in pure water (10 to 30% with respect to pure water), or methylamine (CH3NHz), ethylamine (CH: + CH2NH2), ethanolamine CN
An aqueous solution such as H2CZ H20H) in which fine powder such as silica is mixed and dispersed is used.

A cover 6 is provided around the vacuum chuck 5 to prevent the polishing liquid from scattering around it. This cover 6 has a shaft 1 of the polishing roller 9.
A notch 8 for inserting the cover 6 and a drain 7 for collecting the polishing liquid accumulated in the cover 6 are provided.

FIG. 2 is a perspective view of a grinding and polishing system 30 in which the polishing device 1 described above is attached to a conventional three-axis vertical grinding device 21. As shown in FIG. To briefly explain the three-axis vertical grinding device 21, the upper surface of a table 23 rotatably placed on a base 22 has a suction device that vacuum-adsorbs wafers W, . . . , W. Sections 24, . . . , 24 are provided around the periphery. On the other hand, above the table 23, there are three spindles 25 that are vertically movable and rotationally driven.
25 is provided, and this spindle 25,...
Grinding is performed by the grindstones 26a, 26b, and 26c attached to the lower ends of the wafers W1, . . . , W coming into contact with each other.

The whetstone 26a is round, the whetstone 26b is medium, and the whetstone 26c is fine, and the wafers W1..., W are ground by the whetstones 26a, 26b, 26c in this order.
It is processed to a predetermined thickness and surface roughness.

Note that pure water is supplied as a grinding fluid to the grinding surfaces of the grindstones 26a, 26b, and 26c by appropriate means.

Next, the operation of this polishing apparatus 1 and grinding polishing system 30 will be explained below.

First, the wafer W to be processed is attracted to the suction section 24 of the three-axis vertical grinding device 21 located at the position A in FIG.

The table 23 is rotating counterclockwise, and the wafer W
are sequentially ground by grindstones 26a, 26b, and 26C. The grinding force by the grindstone 26c is
When it reaches position B in the figure, it is transported from the suction part 24 of the three-axis vertical grinding device 21 to the vacuum chuck 5 of the polishing device 1 by a vacuum chuck or the like (not shown).

When the wafer W is attracted to the vacuum chuck 5, the chuck 5
starts rotating, the wafer W also rotates together with the chuck 5, and the polishing roller 9, which is rotationally driven from above, descends, and its outer periphery comes into contact with the processing surface S of the rotating wafer W, and the opening of the nozzle 13 Polycynda liquid is dripped from the part.

When polishing is completed, the polishing roller 9 moves upward, the vacuum chuck 5 stops rotating, and the vacuum chuck 5 of the polishing device 1 is removed by another vacuum chuck (not shown) or the like.
The processed wafer W is removed and transported to the next process.

In addition, in the above embodiment, an example is shown in which the polishing device l is attached to the three-axis vertical grinding device 21, but
The polishing device of the present invention has a wide range of applications and can be used alone or in combination with other types of grinding devices.

- Furthermore, the shape and arrangement of each component of the polishing apparatus of the present invention, such as the polishing roller, are not limited to those of the above embodiments, and can be modified as appropriate.

(g) Effects of the Invention The wafer polishing apparatus of the present invention includes a chuck that is driven to rotate while attaching the wafer, and a polishing roller that is attached to the chuck and is driven to rotate while being in contact with the processing surface of the wafer. Since the present invention is equipped with a polishing liquid supply means for supplying polishing liquid to the processed surface of the wafer, the surface smoothness of the processed surface of the wafer can be improved to 0.043±0.02'. As a result, it has the following advantages.

First, the conventional chemical treatment using strong acids is no longer necessary, making wafer surface finishing work safer and greatly improving the working environment. Pollution prevention equipment such as treatment equipment becomes unnecessary.

Second, as a result of eliminating the need for chemical treatment with strong acids, the wafers are not subjected to more chemical changes than necessary, and the reliability of semiconductor products manufactured from these wafers can be improved.

Thirdly, there is no need to perform the final finishing of the wafer surface as a separate process, and as shown in the embodiment, the polishing device of the present invention can be attached to a conventional grinding device.
Work efficiency is greatly improved.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view of a wafer polishing device according to an embodiment of the present invention, and FIG. 2 shows a wafer polishing device attached to a three-axis vertical grinding device. FIG. 1 is a perspective view of a grinding and polishing system. 5: Vacuum chuck, 9: Polishing roller, 13: Nozzle, W: Wafer, S: Processing surface. Patent applicant ROHM Co., Ltd. agent
Patent Attorney Shigeru Nakamura %1 Figure

Claims (3)

[Claims] (1) A chuck that attaches a wafer and is driven to rotate, a polishing roller that is rotated while contacting the processing surface of the wafer attached to the chuck, and supplies a polishing liquid to the processing surface of the wafer. A wafer polishing apparatus comprising a polishing liquid supply means. (2) The polishing apparatus according to claim 1, wherein the polishing liquid supplied by the polishing liquid supply means is an amine aqueous solution in which abrasive grains are dispersed. (3) The polishing apparatus according to claim 1, wherein the polishing liquid supplied by the polishing liquid supply means is water in which abrasive grains are dispersed.