Supports – Stand – Tilting support surface
Reexamination Certificate
1999-08-02
2001-10-23
Braun, Leslie A. (Department: 3632)
Supports
Stand
Tilting support surface
C248S288510, C324S758010
Reexamination Certificate
active
06305657
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a mechanism for tilting a microscope used for an appearance inspection device capable of inspecting wafers in a process such as during the production of semiconductor devices, after the formation of thin films, after etching or after washing.
2. Description of the Related Art
Objects of which the appearance is to be inspected in the IC process chiefly include photomasks, wafers and reticules. In inspecting pattern defects on the wafers, a microscope is generally and widely used for inspecting irregular line widths, scars, missing portions on the patterns that cannot be discovered by the inspection of electric properties, and for sampling inspection during the production steps.
A wafer is usually inspected by using a microscope in a manner as shown in FIG.
12
. That is, a wafer
3
to be inspected is secured, by vacuum gripping or a similar method, onto a wafer chuck
2
provided on a moving stage
1
that is allowed to move in the x-direction, Y-direction and Z-direction and to rotate in &thgr;-direction. Over the wafer, a microscope
7
is placed via a tilting sub-base, a tilting base
5
and a plate
6
. The microscope is provided with plural kinds of objectives
8
, and a predetermined objective is brought to an inspection position on the wafer that is to be inspected by revolving an electrically-driven revolver
9
.
To vividly and correctly catch the image on the wafer, the optical axis of the objective must be at right angles with the surface of the wafer. Therefore, a tilting mechanism is provided for adjustment. There has heretofore been employed a tilting mechanism shown in
FIGS. 13 and 14
. In order to support the tilting base
5
and the tilting sub-base
4
while maintaining a gap, the tilting mechanism is provided with gap-adjusting means comprising a pair of a fastening bolt
10
and a set screw
11
at four corners. The tilting base
5
has through holes larger than the outer diameter of the bolt for passing the fastening bolt
10
therethrough but smaller than the head of the fastening bolt, and further has threaded holes for the set screws
11
neighboring the through holes. The tilting sub-base
4
has threaded holes for receiving the fastening bolts
10
, and the set screws
11
are set onto the tilting sub-base
4
.
To expand the gap between the tilting base
5
and the tilting sub-base
4
in this tilting mechanism, the fastening bolt
10
is turned and is lifted up to create a gap between the lower surface of the head of the fastening bolt and the upper surface of the tilting base. In this state, the set screw
11
is turned to raise the tilting base
5
so that it comes in contact with the lower surface of the head of the fastening bolt. To narrow the gap, the set screw
11
is turned in the reverse direction to lower the tilting base
5
and, then, the fastening bolt is also turned reverse so as to be screwed therein.
Relying on the operations of both the fastening bolt
10
and the set screw
11
as described above, the gap is adjusted at one corner between the tilting base
5
and the tilting sub-base
4
. Since the supports exist at four points, this operation for adjustment must be executed at all of four points at four corners, which is very cumbersome. This difficulty in the adjustment makes it impossible to accomplish fine adjustment. Also, a change takes place with the passage of time since there remains a large residual stress after the fastening by using the fastening bolts and set screws.
SUMMARY OF THE INVENTION
The present invention was accomplished in view of the problems inherent in the conventional mechanism for tilting a microscope, and its object is to easily carry out the adjustment operation for accomplishing a right-angled relationship between the surface of an object to be inspected and the optical axis of an objective, and for accomplishing a fine and correct adjustment, eliminating a change with the passage of time after the adjustment.
In a mechanism for tilting a microscope according to an embodiment of the present invention, a tilting base and a tilting sub-base are supported at three points, and the tilting base is urged toward the tilting sub-base at all times by springs interposed between support bolts and the tilting base, to easily accomplish fine and correct tilting adjustment.
In a mechanism for tilting a microscope according to the present invention, many initially coned disc springs are used to produce resilient urging force for a heavy load.
In a mechanism for tilting a microscope according to the present invention, one point among the three points serves as a center of the side edge and is used as a reference point for fastening.
In a mechanism for tilting a microscope according to the present invention, the three support points are constituted by a conical receptacle and a steel ball to support the load, by line contact, while providing endurance against a heavy load.
In a mechanism for tilting a microscope according to the present invention, a facing on the tilted sub-base corresponding to a third adjusting bolt is formed like an elongated groove along a line connecting a first adjusting bolt to the third adjusting bolt to cancel the deviating force between the tilting base and the tilting sub-base that stems from the rotational force of the third adjusting bolt at the time of adjusting the tilt.
In a mechanism for tilting a microscope according to the present invention, cylindrical members are fitted to the tilting base so that the second and third adjusting belts can be screwed therein, eliminating the need of forming a screw thread in the tilting base and the need of replacing the tilting base, which is an important component, despite the screw thread being flattened after repetitions of the tilting adjustment, but only requiring the replacement of the cylindrical members to offer an advantage in maintenance and cost.
In a mechanism for tilting a microscope according to the present invention, a facing corresponding to a second adjusting bolt is formed in a ball receptacle which is allowed to slide on the tilting sub-base, to comply with the motion produced by the turn of the third adjusting bolt and to comply with the attitude of the second adjusting bolt.
In a mechanism for tilting a microscope according to the present invention, a leaf spring is provided between the side edges of the tilting base and the tilting subbase to prevent the deviation between the two.
The present invention may be more fully understood from the description of the preferred embodiments of the invention set forth below together with the accompanying drawings.
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Hiranuma Kazunori
Manpuku Yasuhiro
Takashina Mamoru
Braun Leslie A.
Christie Parker & Hale LLP
Le Tan
Tokyo Seimitsu Co. Ltd.
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