Device for exposure of a peripheral area of a wafer

Details Device for exposure of a peripheral area of a wafer Device for exposure of a peripheral area of a wafer

2002-09-16

2004-04-13

Mathews, Alan (Department: 2851)

Photocopying

Projection printing and copying cameras

Step and repeat

C355S067000

Reexamination Certificate

active

06721037

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a device for exposing the outside peripheral area of a semiconductor wafer having a V-shaped notch in its periphery in order to remove a photoresist which has been applied to the surface of the semiconductor wafer.
2. Description of the Related Art
Conventionally, a device for exposure of a peripheral area of a wafer is as shown in FIG.
13
(
a
). During exposure, an area S irradiated with exposure light is moved such that it follows the edge E of the wafer W, and the peripheral area of the wafer W, to which a photoresist R has been applied, is exposed with a given exposure width A.
In the conventional device for exposing a peripheral area, the peripheral area of the wafer W is exposed such that the edge E of the wafer W is always captured. However, in the outside peripheral area a V-shaped notch N is formed. When the wafer W is exposed, the area S irradiated with the exposure light moves in a V-shape in the area of the notch N. As a result, a phenomenon was encountered in that an area UE which is located within the interior of the wafer W and which need not be exposed is also exposed, as shown in FIG.
13
(
b
). Therefore in the vicinity of the above described area UE there can not be an area in which a semiconductor component (a circuit pattern or the like) is formed; this is an impediment to an increase in productivity for semiconductor components. Therefore, the applicant has already proposed, in JP 2001-151037, a device for exposing the peripheral area in which the irradiated area is prevented from moving in a V-shape in the notch area of the wafer, i.e., the area located inside the V-shaped edge area of the wafer which need not be exposed is prevented from being exposed.
Exposure of the peripheral wafer area in the device described in JP 2001-151037 is illustrated in FIGS.
14
(
a
) to
14
(
d
).
In that device for exposing a peripheral area, the exposure light irradiation part which exposes the peripheral area of the wafer is located integrally with a means for wafer edge determination, which follows the edge E of the wafer W and moves in the direction which is essentially perpendicular to a tangent of the edge of the wafer W. The exposure light emitted from the exposure light irradiation part has an irradiation area S which moves in the same direction and by the same amount as the means for wafer edge determination. In this way the peripheral area of the wafer edge E is exposed.
Furthermore, there is a notch determination means, upstream of the wafer edge determination means, for determining the notch of the wafer. In the following, the term “upstream” is defined as the peripheral area of the wafer which moves toward the means for wafer edge determination when the wafer is turned, and the term “downstream” is defined as the peripheral wafer area which moves away from the means for wafer edge determination.
The notch determination means described above is arranged integrally with the means for wafer edge determination and the exposure light irradiation part, and is synchronized with the means for wafer edge determination and is moved in the direction essentially perpendicular to the tangent of the edge of the wafer W.
A condition is described below in which the peripheral area of a wafer has an outside peripheral area provided with a notch and to which a photoresist has been applied. The photoresist is exposed by the above described device to expose a peripheral area by determining the edge of this wafer. In FIGS.
14
(
a
) to
14
(
d
) the notch area of the wafer is shown enlarged.
The wafer W which has been placed on the treatment stage is turned clockwise, as shown in FIGS.
14
(
a
) to
14
(
d
). The means for wafer edge determination determines the edge E of the wafer W at the position. The area S irradiated with the exposure light from the exposure light irradiation part is located on the surface of the wafer W essentially at the same location as the above described position. The notch determination means upstream of the wafer W, i.e., at position
, determines the edge E of the wafer W.
The four situations encountered during exposure will now be described.
(1) When the edge area except for the notch of the wafer is determined by the notch determination means, as is shown in FIG.
14
(
a
):
The means for wafer edge determination follows the wafer edge and moves in the direction essentially perpendicular to the tangent of the edge of the wafer W. The exposure light irradiation part located integrally with it moves together with the wafer edge determination means. The area S irradiated with the exposure light from the exposure light irradiation part therefore follows the wafer edge E and moves. Thus, as shown in FIG.
14
(
a
), the peripheral wafer area is exposed.
(2) When the notch determination means has reached the start of the notch of the wafer, as shown in FIG.
14
(
b
):
When the wafer W turns clockwise and the start Ns of the notch N of the wafer W reaches the determination position
of the notch determination means, the notch determination means outputs an ON signal. In this way, a controller (not shown) computes the time T1 at which the area S irradiated with the exposure light reaches the start Ns of the notch N based on the rotational speed of the wafer W and the distance between the determination position
of the notch determination means and the position of the wafer edge determination means (in this example 5 mm).
(3) When the time T1 has lapsed after the notch determination means has reached the start Ns of the notch, as was shown in FIG.
14
(
c
):
When time T1 elapses after the notch determination means has reached the start Ns of the notch N, the area S irradiated with the exposure light reaches the start Ns of the notch N. In this way, the controller stops the operation in which the wafer edge determination means follows the edge E of the wafer W. Therefore, the wafer edge determination means and the area S irradiated with the exposure light do not follow the notch N, but move along the tangent of the edge E of the area directly in front of the notch N of the wafer W.
The above described controller computes the time T2 at which operation of the wafer edge determination means follows the edge E of the wafer W is restarted after stopping. For example, based on the gap dimensions, the notch N is determined and based on the rotational speed of the wafer W, the time T2 at which the area S travels from the start Ns of the notch N to the end Ne of the notch N is determined.
(4) When time T2 has elapsed, as shown in FIG.
14
(
d
):
When time T2 elapses after the area S has reached the start of the notch Ns, the area S reaches the end Ne of the notch N. The controller then restarts operation in which the wafer edge determination means follows the edge E of the wafer W. In this way the means for wafer edge determination moves such that it follows the wafer edge E. As was shown above using FIG.
14
(
a
), the area S irradiated with the exposure light which has been emitted from the exposure light irradiation part moves in such a way that it follows the wafer edge E. Thus, as shown in FIG.
14
(
d
), the peripheral wafer area is exposed.
By the above described process, the tracking operation of the means for wafer edge determination is stopped after a given time has lapsed, i.e., after it has received the signal which indicates the notch start Ns. The tracking operation of the wafer edge determination means is restarted, after a further given time T2 has elapsed, i.e. when the area S reaches the end Ne of the notch N. By this method the irradiation area in the notch area of the wafer is prevented from following the notch and from moving in a V-shape, and the area located inside the wafer, which need not be exposed, is prevented from being exposed.
In the above described device for exposure of a peripheral area the wafer, the edge determination means moves in the radial direction of the wafer when exposure of the peripheral area starts. When the wafer edge determination means d

Affiliated with

Also associated with

Rating

Device for exposure of a peripheral area of a wafer does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Device for exposure of a peripheral area of a wafer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device for exposure of a peripheral area of a wafer will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3192176