Two speed air cylinder for slit valve motion control

• US 6,173,938 B1
• Filed: 09/22/1998
• Issued: 01/16/2001
• Est. Priority Date: 09/22/1998
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: McAndrew, Robert
• Primary Examiner(s): Recla, Henry J.
• Assistant Examiner(s): MAUST, TIMOTHY LEWIS
• Application Number:
  US09/158,597
• Time in Patent Office: 847 Days
• Field of Search: 251/31, 251/35, 251/48, 914/08, 137/1
• US Class Current: 251/31
• CPC Class Codes: F15B 15/223 having a piston with a piston extension or piston recess which completely seals the main fluid outlet as the piston approaches its end position
• CPC Class Codes: F16K 31/122 the fluid acting on a piston F16K31/143, F16K31/163, F16K31/363, F16K31/383 take precedence
• CPC Class Codes: F16K 51/02 specially adapted for high-vacuum installations

Abstract

A multi-speed slit valve apparatus and method of actuating a slit valve apparatus at least at two distinct speeds is provided. The slit valve apparatus includes a pneumatic cylinder 210 having a primary channel 254, 266 and auxiliary channel 258, 270 at each end, wherein the auxiliary channels 258, 270 have a cross sectional area smaller than that of the primary channels 254, 266. A piston 226 defining a front volume 240 and a back volume 242 is disposed in the cylinder 210 and is reciprocally actuated by a compressed fluid such as air. At a predetermined stage during the cylinder'"'"'s out-stroke and in-stroke the primary channels 254, 266 become sealed from the front and back volumes 240, 242, respectively, such that during the remainder of the stroke the fluid is biased to exhaust through the auxiliary channels 258, 270.

Claims

1. A semiconductor processing system comprising:

a) a transfer chamber having an aperture formed therein to provide access to a semiconductor processing chamber disposed adjacent the transfer chamber;

b) a door adapted to substantially cover the aperture; and

c) a staged variable speed pneumatic cylinder coupled to the door, wherein the pneumatic cylinder comprises;

i) a front primary channel at a front end of the pneumatic cylinder and a back primary channel at a back end of the pneumatic cylinder;

ii) a front auxiliary channel at the front end having a smaller cross sectional area than that of the front primary channel and a back auxiliary channel at the back end of the pneumatic cylinder having a cross sectional area smaller than that of the back primary channel;

iii) a front bridging conduit connecting the front primary channel to the front auxiliary channel and a back bridging conduit connecting the back primary channel to the back auxiliary channel;

iv) a front recess fluidly connected to the front primary channel and a back recess fluidly connected to the back primary channel; and

v) a front sealing element attached on a front piston face and adapted to be received by the front recess and a back sealing element attached on a back piston face and adapted to be received by the back recess.

2. The system of claim 1 further comprising a bumper disposed on the back piston face and positioned to engage a back end cap in the pneumatic cylinder'"'"'s retracted position whereby the back piston face and the back end cap are prevented from contacting.

3. The system of claim 1 further comprising a pressure relief valve disposed in one or both of the auxiliary channels.

4. The system of claim 1 further comprising a compressed fluid source coupled to the front primary channel and the back primary channel.

5. The system of claim 4 wherein the compressed fluid is air.

6. A slit valve door apparatus for a processing system, comprising:

a) at least one slit valve surface having an aperture adapted to provide access to the processing system;

b) a retractable door adapted to substantially cover the aperture; and

c) a staged variable speed pneumatic cylinder coupled to the door, the pneumatic cylinder comprising;

i) a cylinder body defining a cylinder bore enclosed at each end by a front end cap and a back end cap;

ii) a longitudinally reciprocating piston disposed in the cylinder bore defining a front volume and a back volume, the piston having a front piston face and back piston face;

iii) a piston rod secured to the piston at a back end and secured to the door at a front end;

iv) a front sealing element secured to the front piston face;

v) a back sealing element secured to the back piston face;

vi) a front primary channel and a front auxiliary channel connected by a front bridging conduit;

vii) a back primary channel and a back auxiliary channel connected by a back bridging conduit;

viii) a front recess fluidly connecting the front primary channel to the front volume, the front recess having a shape conformed to sealingly receive the front sealing element during the end of an out-stroke of the pneumatic cylinder, whereby the front primary channel becomes substantially sealed from the front volume and fluid is biased to escape from the front volume through the front auxiliary channel during the pneumatic cylinder'"'"'s continuing stroke; and

vii) a back recess fluidly connecting the back primary channel to the back volume, the back recess having a shape conformed to sealingly receive the back sealing element at the end of an in-stroke of the pneumatic cylinder, whereby the back primary channel becomes substantially sealed from the back volume and fluid is biased to escape from the back volume through the back auxiliary channel during the pneumatic cylinder'"'"'s continuing stroke.

7. The apparatus of claim 6 further comprising a compressed fluid source coupled to the front primary channel and the back primary channel.

8. The apparatus of claim 6 further comprising a bumper disposed in the back piston face and positioned to engage the back end cap in the pneumatic cylinder'"'"'s retracted position whereby the back piston face and the back end cap are prevented from contacting.

9. The apparatus of claim 6 further comprising a pressure relief valve disposed in at least one of the auxiliary channels.

10. A semiconductor processing system comprising:

a) a first vacuum chamber having an aperture formed therein to provide access to a second vacuum chamber disposed adjacent the first vacuum chamber;

b) a door adapted to substantially cover the aperture; and

c) a staged variable speed pneumatic cylinder coupled to the door and adapted to reduce a speed of the door during a terminal portion of travel prior to covering the aperture, wherein the pneumatic cylinder comprises;

i) a front primary channel at a front end of the pneumatic cylinder and a back primary channel at a back end of the pneumatic cylinder;

ii) a front auxiliary channel at the front end having a smaller cross sectional area than that of the front primary channel and a back auxiliary channel at the back end of the pneumatic cylinder having a cross sectional area smaller than that of the back primary channel;

iii) a front bridging conduit connecting the front primary channel to the front auxiliary channel and a back bridging conduit connecting the back primary channel to the back auxiliary channel;

iv) a front recess fluidly connected to the front primary channel and a back recess fluidly connected to the back primary channel; and

v) a front sealing element attached on a front piston face and adapted to be received by the front recess and a back sealing element attached on a back piston face and adapted to be received by the back recess.

11. The system of claim 10 further comprising a bumper disposed on the back piston face and positioned to engage a back end cap in the pneumatic cylinder'"'"'s retracted position whereby the back piston face and the back end cap are prevented from contacting.

12. The system of claim 10 further comprising a pressure relief valve disposed in one or both of the auxiliary channels.

13. The system of claim 10 further comprising a compressed fluid source coupled to the front primary channel and the back primary channel.

14. The system of claim 13 wherein the compressed fluid is air.