High vacuum dual stage load lock and method for loading and unloading wafers using a high vacuum dual stage load lock

• US 6,048,154 A
• Filed: 10/02/1996
• Issued: 04/11/2000
• Est. Priority Date: 10/02/1996
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Wytman, Joe
• Primary Examiner(s): Bucci, David A.
• Application Number:
  US08/725,275
• Time in Patent Office: 1,287 Days
• Field of Search: 414/217, 414/416, 414/331, 414/937, 414/939, 414/940, 414/786, 414/411, 414/805, 414/811, 414/331.14, 414/331.18, 204/298.25, 204/298.35, 118/719, 156/345
• US Class Current: 414/217
• CPC Class Codes: H01L 21/67748 horizontal transfer of a single workpiece
• CPC Class Codes: H01L 21/67757 vertical transfer of a batch of workpieces
• CPC Class Codes: Y10S 414/137 including means for charging or discharging wafer cassette
• CPC Class Codes: Y10S 414/139 including wafer charging or discharging means for vacuum chamber
• CPC Class Codes: Y10S 414/14 Wafer cassette transporting

Abstract

A dual stage load lock is provided for transfer of semiconductor wafers between an environment at atmospheric pressure and a high vacuum environment, such as a wafer processing system. The dual stage load lock includes a first load lock chamber and a second load lock chamber separated by a dividing ledge which extends a distance inwardly from the inner wall of the load lock assembly. The lower load lock chamber selectively communicates with a transfer chamber of the processing system, and is maintained at high vacuum. The upper load lock chamber selectively communicates with the external environment at atmospheric pressure. Therefore, the environment of the upper load lock chamber may vary between atmospheric pressure, when wafers are transferred between the load lock and the outside environment, and high vacuum, when the wafers are transferred between the first and second chambers of the load lock. The load lock may include modular chamber segments that can be arranged in a variety of configurations. A method for transferring wafers through the load lock is also provided.

Claims

1. A load lock apparatus for transferring an article between a first environment at substantial atmospheric pressure and a high vacuum processing system comprising:

a first chamber having an environment adjustable between substantially atmospheric pressure and vacuum and in selective communication with said first environment;

a second chamber maintained in high vacuum and in selective communication with said first chamber;

one of said first chamber and said second chamber in selective communication with said processing system;

a cover for selectively separating said first chamber environment from said second chamber environment;

a valve for providing selective communication between said first chamber and said vacuum processing system;

an aperture between said first chamber and said second chamber, and an aperture cover selectively sealingly blocking communication of said first chamber and said second chamber via said aperture;

wherein said aperture cover is a plate located within said second chamber;

said first chamber further including a moveable stage upon which the article is positionable; and

wherein said plate is connected to, and positioned within said second chamber by positioning of said stage.

2. A method for transferring an article between an ambient atmospheric pressure environment and a processing vacuum environment, through a load lock chamber having loading and transfer chambers that are separated by a ledge having an opening for passing the article there between, the ledge having a first side that faces the loading chamber and a second side that faces the transfer chamber, comprising:

moving an article-bearing stage contained within the transfer chamber toward the second side to operably abut the ledge to create fluid isolation between the loading and transfer chambers to allow ambient atmospheric and vacuum pressures to coexist in the loading and transfer chambers respectively;

loading the article from the first ambient atmospheric pressure environment into the loading chamber onto the article-bearing stage while the loading chamber is at ambient atmospheric pressure and in fluid isolation from the transfer chamber with the transfer chamber being at a vacuum pressure;

moving a moveable subchamber contained within the loading chamber toward the article-bearing stage to cooperate with the ledge and article bearing stage to create a sealing surroundment of the article;

evacuating the moveable subchamber to a pressure substantially equal to the vacuum of the transfer chamber;

lowering the article-bearing stage away from the second side of the ledge, whereby the article is moved from the loading chamber into the transfer chamber;

transferring the article from the transfer chamber to the processing vacuum environment.

3. The method of claim 2, further comprising conditioning the article after the step of moving the moveable subchamber to cooperate with the ledge and article bearing stage to create a sealing surroundment of the article, but prior to the step of moving the article from the loading chamber to the transfer chamber.

4. A method for transferring an article between a first ambient atmospheric pressure environment and a processing vacuum environment, through a load lock chamber having selectively separable first and second chambers, comprising:

maintaining the second chamber at a vacuum;

transferring the article from the processing environment onto a controllably moveable pedestal in the second chamber while an interior region of the first chamber exterior to a moveable subchamber within the first chamber is in fluid isolation from the second chamber;

moving the pedestal upward to position the article into the moveable subchamber and to cause the pedestal to cooperate with a ledge projecting inward from the load lock chamber to create fluid isolation between the subchamber and second chamber to allow ambient atmospheric pressure and high vacuum to coexist in the subchamber and second chamber respectively;

adjusting the moveable subchamber to ambient atmospheric pressure;

raising the moveable subchamber; and

transferring the article from the first chamber to the first ambient atmospheric pressure environment.

5. The method of claim 4, further comprising conditioning the article after the step of fluid isolation between the first and second chambers, but before the step of raising the moveable subchamber.