Geometrical instruments – Gauge – Collocating
Reexamination Certificate
2002-05-08
2004-03-16
Bennett, G. Bradley (Department: 2859)
Geometrical instruments
Gauge
Collocating
C033S502000
Reexamination Certificate
active
06705020
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of and apparatus for use in orienting an object at a predetermined reference angle with respect to a given plane(s). More particularly, the present invention relates to a process of aligning a chuck relative to equipment by which a substrate supported by the chuck will be processed.
2. Description of the Related Art
Currently, semiconductor memory devices are being developed at a rapid pace due to the widespread use of computers for processing various types of information. To this end, the current art is focused on developing and realizing memory devices having a high degree of integration, response speed, and reliability. Accordingly, highly precise process techniques are required for fabricating today's semiconductor memory devices.
Semiconductor devices are fabricated by such processes as an ion implantation process, a thin film forming process and a patterning process. Needless to say, all of the conditions under which these fabrication processes are performed must be controlled. If the process conditions are not completely controlled, process errors may be generated. Moreover, a semiconductor substrate is supported by a chuck during semiconductor device fabrication processing, such as during the thin film forming process, pattern forming process, and ion implantation process. Therefore, one of the process conditions usually requiring control is the positioning or aligning of the chuck on which the semiconductor substrate is placed.
The position of the chuck is controlled as follows, using the ion implantation process as an example.
Referring to
FIG. 1
, a substrate
10
should be tilted relative to an ion beam during the implantation process to prevent a channeling effect from occurring. The channeling effect refers to a situation in which ions injected into the substrate pass through voids in the substrate, i.e., spaces where atoms are not present. Japanese Patent Laid-Open Publication No. 2000-68226 and U.S. Pat. No. 5,406,088 (issued to Brune, et al.) each disclose a method of preventing the channeling effect from occurring during the ion implantation process. More specifically, Japanese Patent Laid-Open Publication No. 2000-68226 discloses a method in which the scanning angle of an ion beam is controlled to prevent the channeling effect. On the other hand, U.S. Pat. No. 5,406,088 discloses a method in which the chuck is manipulated to prevent the channeling effect.
In the latter case, the chuck on which the substrate
10
is placed is preferably tilted at the angle of 7 degrees with reference to the vertical before the ion implantation process begins. The process of tilting the chuck to position the substrate
10
relative to the ion beam will hereinafter be referred to as the process of aligning the chuck.
The process of aligning the chuck includes the steps of first orienting the chuck vertically and then tilting the chuck 7 degrees with respect to the vertical. The step of orienting the chuck vertically is performed by a reference angle providing apparatus shown in FIG.
2
.
Referring to
FIG. 2
, the reference angle providing apparatus
20
is disposed on the bottom surface
17
of the process chamber. The reference angle providing apparatus
20
includes a surface contact portion
200
that makes surface contact with the chuck
15
, and a supporting portion
210
for supporting the surface contact portion
200
. The supporting portion
210
includes a supporting bar
210
a
for supporting the surface contact portion
200
and a bottom portion
210
b
for supporting the supporting bar
210
a
. The bottom portion
210
b
is mounted to the bottom surface
17
of the process chamber. The chuck
15
is also mounted to the bottom surface
17
of the chamber.
The surface contact portion
200
of the reference angle providing apparatus
20
is brought into contact with the chuck
15
before the ion implantation process begins. An alignment error is judged to occur at that time if the entire surface of the contact portion
200
does not contact the chuck
15
. In that case, X and Y coordinates of the chuck are adjusted such that the chuck
15
contacts the entire surface of the contact portion
200
. Preferably, the chuck
15
is oriented at an angle of 0 degrees relative to the X-Y plane (the vertical) and at an angle of 90 degrees relative to the Y-Z plane (the horizontal). Once the chuck
15
and the surface contact portion
200
are in complete surface contact with each other, the chuck
15
is tilted at an angle of 7 relative to the X axis.
However, the reference angle supplying apparatus
20
is subject to the following problems. First, the apparatus
20
itself is moved manually to place the surface contact portion
200
in contact with the chuck
15
. Therefore, the apparatus is shaken during this operation, which shaking can cause an alignment error to occur. Also, alignment errors are produced because the bottom portion
210
b
of the reference angle supplying apparatus
20
is often does not lie precisely flat on the bottom surface
17
of the chamber. Still further, the state of contact between the chuck
15
and the surface contact portion
200
is judged by an operator, whereby the alignment process is prone to human error. Furthermore, the precision or calibration of the reference angle supplying apparatus
20
degrades over time. However, the apparatus
20
has no means by which its own misalignment can be detected. Therefore, the apparatus
20
may be operated continuously while being out of self-alignment. As a result, the chuck
15
is oriented improperly by the apparatus
20
.
For the reasons described above, process errors frequently occur when the chuck is aligned using the conventional reference angle providing apparatus. Accordingly, these errors translate so much into the process of fabricating the semiconductor device that the productivity of the fabricating process suffers.
SUMMARY OF THE INVENTION
An object of the present invention is to obviate the above-described problems of the prior art. Accordingly, an object of the present invention is to provide a method and apparatus by which an object to be aligned may first be oriented precisely at a desired reference angle.
To achieve this object, the present invention provides an apparatus for providing an object with a reference angle, which apparatus comprises a main body and a pin gauge for making point contact with the surface of the object.
The pin gauge has at least two projections which project in the direction of a Z axis away from an end surface of the body. Two or more of the projections are located on X and Y axes, respectively, orthogonal to one another and to the Z axis and spaced from the origin of the coordinate system defined by the X, Y and Z axes.
In addition, a mechanical drive member(s) is/are used to bring the pin gauge into initial contact with the object to be aligned. In particular, a horizontal support having a horizontal guide engaged with the main body, and a horizontal drive member are used to move the body horizontally in the direction of the Z axis (longitudinal direction of the projections of the pin gauge) to bring the pin gauge into initial point contact with the object. A vertical support having a vertical guide, and a vertical drive may also be provided to bring the pin gauge up or down to the level of the object to be aligned.
The vertical support may include a bottom member on which the horizontal support is disposed, and a vertical member on which the vertical guide is disposed. The vertical guide is engaged with at least the horizontal support.
Each mechanical drive member preferably comprises a fixed nut and a drive screw connected to the main body and threaded with the fixed nut. Thus, the drive screw and the body of the apparatus connected thereto will be moved linearly when the drive screw is rotated relative to the fixed nut. An actuating member, such as a knob, allows the drive screw to be rotated.
Preferably, the projections comprise proximity sensors f
An Gum-Chan
Choi Ki-Cheol
Hong Hyung-Sik
Jung Byoung-Sik
Keum Gyeong-Su
Bennett G. Bradley
Samsung Electronics Co Ltd.
Volentine & Francos, PLLC
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