Wafer release mechanism
View Patent ↗The present disclosure describes a method that prevents pre-mature dc-chucking in processing modules. The method includes placing a wafer onto a chuck equipped with lift pins. One or more of the lift pins include a pressure sensor configured to measure a pressure exerted by the wafer. The method further includes measuring a first pressure applied to the one or more lift pins by the wafer, lowering the lift pins to place the wafer on the chuck, and processing the wafer. The method also includes removing the wafer from the chuck by pressing the one or more lift pins against the wafer to measure a second pressure exerted by the wafer. If the measured second pressure is equal to the first pressure, the method raises the wafer using the lift pins above the chuck.
1 . A processing module, comprising:
a chuck;
a wafer lift mechanism comprising one or more lift pins configured to raise a wafer from the chuck or lower the wafer onto the chuck, wherein the one or more of the lift pins comprises a pressure sensor configured to measure a pressure exerted on the one or more lift pins by the wafer, and wherein the pressure comprises a weight of the wafer and a differential pressure due to a vacuum created on a backside of the wafer by the chuck; and
a gas source configured to flow a gas over the wafer in response to the measured pressure being greater than a pressure corresponding to a weight of the wafer.
2 . The processing module of claim 1 , wherein the pressure sensor has a cross-sectional area that is substantially equal to or smaller than a cross-sectional area of the one or more lift pins.
3 . The processing module of claim 1 , wherein the gas comprises an inert gas.
4 . The processing module of claim 1 , wherein the gas comprises helium, argon, xenon, or neon.
5 . The processing module of claim 1 , wherein the pressure sensor is configured to be pressed against a backside surface of the wafer to measure the pressure exerted on the one or more lift pins by the wafer.
6 . The processing module of claim 1 , wherein the pressure sensor is disposed on a top surface of the one or more lift pins and has a diameter that ranges from about 1 mm to about 5 mm.
7 . The processing module of claim 1 , wherein the wafer lift mechanism comprises three or more lift pins with pressure sensors thereon.
8 . The processing module of claim 1 , wherein each of the one or more lift pins is configured to maintain a respective pressure sensor at a temperature below about 110° C.
9 . The processing module of claim 1 , wherein the pressure sensor is further configured to transmit a pressure reading that corresponds to the measured pressure via one or more of a wired connection, a wireless connection, and combinations thereof.
10 . The processing module of claim 1 , wherein the chuck is one of a vacuum chuck.
11 . A processing module, comprising:
a chuck with lift pins configured to raise and lower a wafer;
a pressure sensor integrated into one or more of the lift pins, the pressure sensor configured to:
measure a pressure exerted by the wafer on the lift pins; and
measure a differential pressure at a backside of the wafer relative to that at a front side of the wafer, wherein the differential pressure is due to a vacuum provided by the chuck; and
a gas line configured to flow an inert gas over the wafer.
12 . The processing module of claim 11 , wherein the chuck is a vacuum chuck configured to apply the differential pressure to the wafer to secure the wafer onto the chuck.
13 . The processing module of claim 12 , wherein the gas line is configured to equalize the differential pressure by flowing the inert gas to release the wafer from the chuck.
14 . The processing module of claim 11 , wherein the inert gas increases a pressure on the backside of the wafer.
15 . The processing module of claim 11 , wherein each of the lift pins is hollow.
16 . The processing module of claim 11 , wherein water is circulated through a hollow portion of each of the lift pins.
17 . The processing module of claim 11 , wherein the chuck is configured to release an inert gas through a plurality of holes to increase a pressure on the backside of the wafer.
18 . A chuck, comprising:
a plurality of lift pins configured to:
lower a wafer; and
raise the wafer after a wafer process is completed; and
a pressure sensor incorporated as a cylindrical cap on a top surface of each one of the plurality of lift pins, wherein the pressure sensor is configured to measure a pressure exerted on the one or more lift pins by the wafer, and wherein the pressure comprises a weight of the wafer and a differential pressure due to a vacuum created on a backside of the wafer by the chuck.
19 . The chuck of claim 18 , wherein the pressure sensor is one or more of an electromagnetic pressure sensor, a capacitive pressure sensor, a piezoresistive pressure sensor, and an optical pressure sensor.
20 . The chuck of claim 18 , wherein the pressure sensor comprises a wireless transmitter.