Patent Application
20080061519
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention, however, may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.
While a wafer W will now be described below as an example of a substrate, the present invention is not limited thereto.
The spin head 1 includes a disk-shaped plate 10 and a plurality of chucking pins 100 disposed on the plate 10 along the edge of the plate 10. The plate 10 has the shape of a disk having the same size as the wafer W. A plurality of through-holes 12 are formed at the top surface of the plate 10 along the edge of the plate 10. A chucking pin 100 is installed on the through-hole 12.
The through-holes 12 are spaced at regular intervals and regular angles θ around the center of the plate 10 such that the chucking pins 100 apply an equivalent force to the wafer W. In this embodiment, six through-holes 12 are formed at the plate 10 and the angle θ between the through-holes 12 is 60 degrees. However, in the case the number of through-holes 12 provided is not six, the angle θ between the through-holes 12 is variable with the number of the through-holes 12 provided.
On the other hand, a rotation shaft 14 is connected to the bottom of the plate 10. The rotation shaft 14 is rotatable by means of a separate driving unit (not shown).
The chucking pin 120 supports a wafer W while being in contact with the edge of the wafer W. The chucking pin 120 is disposed to be eccentric from the rotation center A of a rotation shaft 160 which will be described later. Therefore, the chucking pin 120 may come in contact with the edge of the wafer W or may be spaced apart therefrom through its rotation.
As illustrated, the chucking pin 120 includes a first front-end portion 122 disposed at the front end and a first back-end portion 124 disposed at the back end. The first front-end portion 122 has a first tip 122a, which has the shape of a tip. The first back-end portion 124 has a streamline-shaped cross section, which has a round shape. The top surface of the chucking pin 120 is inclined downwardly toward the first back-end portion 124 from the first front-end portion 122. The first front-end portion 122 comes in contact with the edge of the wafer W or is spaced apart therefrom through its rotation, which will be described in detail later.
The body 140 is provided to support the chucking pin 120, and the rotation shaft 160 is connected to the bottom of the body 140. The rotation of the rotation shaft 160 allows the body 140 and the chucking pin 120 to rotate with each other.
As illustrated, the body 140 has a second front-end portion 142 disposed at the front end and a second back-end portion 144 disposed at the back end.
The second front-end portion 142 has a second tip 142a, which has the shape of a tip. The second back-end portion 144 has a streamline-shaped cross section, which has a round shape. The top surface of the body 140 is inclined downwardly toward the second back-end portion 144 from the second front-end portion 142. Since the rotation shaft 160 is connected to the bottom of the second back-end portion 124, the rotation of the rotation shaft 160 allows the second front-end portion 142 to approach a wafer W or to be spaced apart from the wafer W. This will be described in detail later.
The rotation shaft 160 rotates on its rotation center A by means of a separate driving unit (not shown). A wafer W is chucked or unchucked by the rotation of the rotation shaft 160. As described above, the rotation of the rotation shaft 160 allows the first and second front-end portions 122 and 142 to approach the wafer W or to be spaced apart from the wafer W.
As previously stated, if a chucking member 100 rotates on a rotation shaft A, a first front-end portion 122 of a chucking pin 120 comes in contact with the edge of a wafer W and the wafer W is supported by the first front-end portion 122.
If the supported wafer W rotates anticlockwise, an air current U is generated clockwise. As illustrated in
Relative to the air current U, first and second front-end portions 122 and 142 are disposed at the front end and first and second back-end portions 124 and 144 are disposed at the back end. Thus, the air current U over the wafer W is discharged outside the wafer W through the first back-end portion 124 along a first tip 122a of the first front-end portion 122. On the other hand, the air current under the wafer W is discharged outside the wafer W through the second back-end portion 144 along a second tip 142a of the second front-end portion 142. Since cross sections of the chucking pin 120 and the body 140 are streamline sections, a vortex is not generated at the back end of the first and second back-end portions 124 and 144.
The “streamline” means an object's shape for alleviating the resistance generated when the object moves in a fluid. For example, the body of a fish and the hull and wing of an airplane has the shape of “streamline”. A vortex generated at the back of an object is the major factor, which reduces a pressure at the back of the object to generate a drag. Accordingly, the streamline is an appearance for suppressing turbulence at the back of the object. From the type of air current, the principles for streamline are as follows: (1) a front portion of an object should be round enough; and (2) an object should has a curve tapered to the center from the back of the object. As previously described in this embodiment, a tip is formed at the front end and a front end portion is round. However, a tip may be formed at the back end and a front end portion may be round. Moreover, various types of streamline may be applied.
If a tangent line is drawn to a contact point of the wafer W that is in contact with the first front-end portion 122, an angle θ is defined between a straight line running from the rotation center A to the first tip 122a and the tangent line. The angle θ is very significant. That is, the flow of air current U is increasingly blocked with the increase of the angle θ. On the other hand, the flow of air current U becomes smooth with the decrease of the angle θ.
First and second tips 122a and 142a approach the wafer W through their rotation. Since they has the shape of a tip, it may be possible to prevent a treating solution dispersed to the outside of the wafer W from the top or bottom surface of the wafer W from reflowing in the wafer W after colliding against a chucking pin 120 or a body 140.
As illustrated in
Due to the rotation of a wafer W, a treating solution supplied to the top surface of the wafer W is drained outside the wafer W. However, the treating solution may reflow in the top surface of the wafer W by means of a chucking pin 120 configured to support the wafer W. As described above, the top surface of the chucking pin 120 is inclined to make only a portion of the chucking pin 120 higher than the top surface of the wafer W. Therefore, it may be possible to prevent the treating solution from reflowing in the wafer W.
According to the present invention, an air current generated by the rotation of a substrate is smoothly discharged outside the substrate along circumferential surfaces of a chucking pin and a body which has the shape of a streamline. Moreover, a treating solution drained outside the substrate is prevented from reflowing in a rear surface of the substrate due to a chucking member.
Although the present invention has been described in connection with the embodiment of the present invention illustrated in the accompanying drawings, it is not limited thereto. It will be apparent to those skilled in the art that various substitutions, modifications and changes may be made without departing from the scope and spirit of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2006-0087948 | Sep 2006 | KR | national |
