Adhesive bonding and miscellaneous chemical manufacture – Surface bonding means and/or assembly means therefor – Automatic and/or material-triggered control
Reexamination Certificate
1998-01-29
2001-02-06
Gray, Linda L. (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Surface bonding means and/or assembly means therefor
Automatic and/or material-triggered control
C156S358000, C156S362000, C156S378000, C156S516000, C156S563000, C156S583200, C378S073000, C125S021000, C125S035000, C125S016010, C356S030000, C356S031000
Reexamination Certificate
active
06182729
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a system that slices silicon ingots used as the material for semiconductors, or the like. The present invention also relates to a method and apparatus for adhering ingots to support members, which are used to mount ingots on slicing machines, and an ingot slicing method.
2. Description of the Related Art
Semiconductor wafers are generally formed by slicing ingots, which are constituted by silicon monocrystals, into a predetermined thickness using a wire saw or the like. An example of one method to slice the ingots will now be described. As shown in
FIG. 3
, an ingot
13
is lifted out of a crucible (not shown) and machined cylindrically. An intermediate plate
20
, which is made of carbon or the like, is adhered to the cylindrical surface of the ingot
13
. A support plate
21
(
FIG. 6
) is adhered to the upper surface of the intermediate plate
20
with a glass insulating plate
21
a
arranged therebetween. As shown in
FIG. 13
, the ingot
13
is mounted on a wire saw
326
by way of the support plate
21
.
The wire saw
326
includes a plurality of rollers
327
, a wire
328
wound spirally around the rollers
327
with a predetermined pitch between each winding, and supply pipes
329
through which slurry containing abrasive grains is supplied to the wire
328
. As shown in
FIG. 8
, the wire
328
is drawn in either a single direction or two directions while the slurry, which includes abrasive grains, is supplied to the wire
328
.
In this state, the wire
328
is pressed against the ingot
13
.
This enables the wire saw
326
to slice the ingot
13
and produce a plurality of wafers
13
a
simultaneously.
The silicon monocrystals, in the form of ingots, have an accurate lattice structure. Such monocrystals have certain crystal planes and crystal orientations. The physical and chemical characteristics of the ingot are affected by the crystal orientation of the monocrystals. The crystal orientation refers to a direction perpendicular to the crystal plane. Prior to the slicing, the crystal orientation of the ingot with respect to the axis of the ingot differs from one ingot to another. Accordingly, slicing ingots having different crystal orientations in the same manner results in the wafers having differing characteristics since the relationship between the sliced surface and the crystal plane is not constant in each wafer.
To cope with this problem, an ingot angle setting device is arranged on the wire saw. The support plate holding the ingot is secured to the angle setting device by bolts. In this state, the displacement of the ingot's crystal orientation with respect to the ingot's axis in horizontal and vertical directions is measured by a goniometer. The angle setting device then appropriately aligns the ingot's crystal orientation with the wire traveling direction. More specifically, the angle setting device pivots the ingot along a horizontal plane and along a vertical plane so as to align the crystal orientation of the ingot with a vertical plane perpendicular to each winding of the wire. In other words, as shown in the flowchart of
FIG. 50
, in the slicing step of the prior art, the ingot, to which the support plate is adhered, is first mounted on the wire saw. The crystal orientation of the ingot is then measured. Afterwards, the ingot is sliced apart into wafers.
However, it is required that each wire saw be provided with an angle setting device. Thus, when using a plurality of wire saws, the cost of the entire system including the wire saws is increased. Furthermore, the attachment of the ingots to the angle setting device is performed manually. This is burdensome for the operator and takes a great deal of time. As a result, attaching the ingots decreases the operational time of the wire saws.
A typical wafer production system includes an adhering step in which the above plates are adhered to the ingot, a mounting step in which the ingots are mounted on the wire saws, an adjusting step in which the crystal orientation of the ingots is measured and adjusted, and a slicing step in which the ingots are sliced. The wafer production system may further include a separating step in which the sliced wafers are separated from one another, a washing step in which the wafers are washed, an inspecting step in which the wafers are inspected, and other steps. In prior art production systems, these steps are performed in an off-line manner. Thus, the mounting, removing, and transporting of the ingots and wafers with respect to the associated apparatus is often performed manually.
However, there is a recent trend in production systems in which the dimensions (diameter and length) of the ingots are becoming larger. This has resulted in the manual mounting, removing, and transporting of the ingots and wafers becoming more burdensome. In addition, since the management of each step is performed manually, it is difficult to increase the manufacturing efficiency of the wafers while upgrading the quality of the wafers.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to reduce the costs required for the entire wafer production system.
It is another object of the present invention to increase the operational time of an ingot slicing apparatus.
It is a further object of the present invention to automate the wafer production system to increase the manufacturing efficiency of the wafers and upgrade the quality of the wafers.
To achieve the above objects, a method for adhering support members to a cylindrical ingot is proposed. The ingot has a crystal orientation. A support plate is mounted on a machine for slicing the ingot. The method comprises rotating the ingot about a center axis thereof, the center axis being held to be parallel to a prescribed first plane so that the crystal orientation is placed in a plane parallel to the first plane, adjusting a position of one of the support plate and the ingot in the plane parallel to the first plane so that a mounting axis extending along a longitudinal direction of the support plate is aligned to the crystal orientation, and adhering the ingot to the support plate.
According to another aspect of the present invention, an apparatus for adhering support members to a cylindrical ingot is proposed. The ingot has a crystal orientation. A support plate is mounted on a machine for slicing the ingot. The apparatus has a measuring device for measuring the crystal orientation of the ingot based on a diffraction of X-rays. Based on the measured crystal orientation, a rotating device rotates the ingot about a center axis thereof which is kept parallel to a prescribed first plane so that the crystal orientation is placed in a plane parallel to the first plane. Based on the measured crystal orientation, an adjusting device adjusts a position of one of the support plate and the ingot in the plane parallel to the first plane so that a mounting axis extending along a longitudinal direction of the support plate is aligned to the crystal orientation. An adhering device adheres the ingot to the support plate.
According to a further aspect of the present invention, a method for slicing a cylindrical ingot by a wire of a wire saw is proposed. The ingot has a crystal orientation. The method comprises rotating the ingot about a center axis thereof, the center axis being held to be parallel to a prescribed first plane so that the crystal orientation is placed in a plane parallel to the first plane, adjusting a position of one of the support plate and the ingot in the plane parallel to the first plane so that an mounting axis extending along a longitudinal direction of a support plate to be mounted to the wire saw is aligned to the crystal orientation, adhering the ingot to the support plate after the adjusting step, transferring the ingot carrying the support plate to the wire saw, mounting the support plate carried by the ingot to the wire saw with the mounting axis being perpendicular to the wire, and slicing the ingot mounted to th
Banzawa Yoshiaki
Hayashi Nobuaki
Shimizu Kiyoakira
Gray Linda L.
Nippei Toyama Corporation
Stetina Brunda Garred & Brucker
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