Backside cannelure to provide for wafer shift detection

Details Backside cannelure to provide for wafer shift detection Backside cannelure to provide for wafer shift detection

2002-03-19

2003-06-10

Whitehead, Jr., Carl (Department: 2813)

Semiconductor device manufacturing: process

With measuring or testing

C356S614000, C438S005000, C438S800000, C118S690000

Reexamination Certificate

active

06576483

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to electrodes on which semiconductor wafers are clamped and that have cannelures against the backsides of the wafers, and more particularly to using such cannelures to provide for detection of wafer shift of the wafers when the wafers are clamped to the electrodes.
BACKGROUND OF THE INVENTION
Electrodes area used in a variety of different semiconductor fabrication processes. Typically, a semiconductor wafer is clamped to an electrode, and the backside is exposed to a gas, such as helium, through a cannelure, or groove, in the electrode. The gas ensures that there is a uniform thermal media throughout the semiconductor fabrication process being performed. In some semiconductor fabrication processes, the frontside of the clamped semiconductor wafer is exposed to plasma, as is the case in various dry etching semiconductor fabrication processes.
FIG. 1
shows a side cross-sectional view of a typical system
100
in which a semiconductor wafer
112
is clamped to an electrode
106
, via a clamp
104
. The electrode is situated within a ring
102
. The clamp
104
and the ring
102
may have various holes for mounting and other purposes that are not shown in FIG.
1
. The cannelure
110
, or groove, within the electrode
106
, faces the backside of the semiconductor wafer
112
. Holes
108
connected to the cannelure
110
allow for a gas to be piped in, and to which the backside of the semiconductor wafer
112
is exposed. On the frontside of the wafer
112
, the wafer
112
may be exposed to plasma in certain semiconductor fabrication processes.
A problem that can occur within the system
100
of
FIG. 1
is that the semiconductor wafer
112
shifts even though it is clamped by the clamp
104
. For instance, the wafer
112
may rotate, change orientation, or tilt, among other different kinds of shifting. Such shifting can likely expose the electrode
106
to the plasma or other material to which the frontside of the wafer
112
is being exposed. This is shown in
FIG. 2
, which is a top view of the system
100
, in which some components of the system
100
have been omitted for illustrative clarity.
In
FIG. 2
, the semiconductor wafer
112
has rotated to the right within and relative to the clamp
104
, as indicated by the arrow
202
. Thus, the flat
204
of the semiconductor wafer
112
, which should be aligned to the bottom of the clamp
104
, over the flat
206
of the electrode
106
, has instead rotated to the right. As shown in
FIG. 2
, this exposes the electrode
106
. In the case where the frontside of the wafer
112
has been exposed to plasma, this means that this part of the electrode
106
has also now been exposed to plasma.
Such plasma exposure of the electrode
106
, however, can have disadvantageous consequences. Arcing may result, potentially damaging the electrode
106
. Furthermore, the arcing may cause undesired particles to be formed on the semiconductor wafer
112
, which can decrease semiconductor device yield, and also cause wafer scrap. Wafer scrap and reduced device yield are costly to the semiconductor foundry fabricating the devices, especially when it cannot pass these costs along to the customer.
Therefore, there is a need for semiconductor wafer shift detection when the wafer has been clamped to an electrode having a cannelure that exposes the backside of the wafer to gas. Such detection should be sensitive and fast enough to detect wafer shift before the electrode has a chance to arc, in the case where the frontside of the semiconductor wafer is exposed to plasma. For these and other reasons, there is a need for the present invention.
SUMMARY OF THE INVENTION
The invention relates to a backside cannelure of an electrode to provide for detecting semiconductor wafer shift after the wafer has been positioned over the cannelure of the electrode. The wafer has a backside and a proper position over the cannelure. The cannelure exposes the backside of the wafer to a gas piped in through one or more holes of the electrode. The cannelure has a size such that deviation of the wafer from its proper position by more than a threshold partially exposes the cannelure, such that the gas leaks from the cannelure as now partially exposed. A gas flow detector may detect the gas leaking from the cannelure, and provide corresponding detection of the wafer deviating from its proper position.
Embodiments of the invention provide for advantages over the prior art. Sizing the cannelure so that the cannelure is exposed when the semiconductor wafer deviates from its proper position causes gas to leak through the cannelure. A backside gas flow detector detects this increased flow of gas, such that it can be concluded that the semiconductor wafer has shifted. Power to the electrode can then be disconnected before arcing occurs, preventing damage to the electrode or the semiconductor wafer. That is, the gas detection is fast and sensitive enough to prevent such electrode and/or wafer damage. Still other advantages, aspects, and embodiments of the invention will become apparent by reading the detailed description that follows, and by referring to the accompanying drawings.


REFERENCES:
patent: 3711676 (1973-01-01), Witzel
patent: 5133284 (1992-07-01), Thomas et al.
patent: 5695568 (1997-12-01), Sinha et al.

Affiliated with

Also associated with

Rating

Backside cannelure to provide for wafer shift detection does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Backside cannelure to provide for wafer shift detection, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Backside cannelure to provide for wafer shift detection will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3143918