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

• US 6,254,328 B1
• Filed: 06/15/1999
• Issued: 07/03/2001
• Est. Priority Date: 10/02/1996
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Wytman, Joe
• Primary Examiner(s): Bratlie, Steven A.
• Application Number:
  US09/333,358
• Time in Patent Office: 749 Days
• Field of Search: 414/217, 414/805, 414/939
• 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 an ambient atmospheric pressure environment and a high vacuum environment, the apparatus comprising:

an article chamber having an interior demarked into axially aligned loading and transfer chambers by a ledge projecting into the interior;

a pedestal projecting into and axially transposable within the transfer chamber to selectively position an article-bearing stage in sealing engagement with the ledge to create fluid isolation between the loading and transfer chambers to allow ambient atmospheric pressure and high vacuum to coexist in the loading and transfer chambers respectively, and such that articles positioned on the stage are projected into the loading chamber and in fluid isolation from the transfer chamber; and

an open-ended, pressure adjustable, sub-chamber within the loading chamber, the sub-chamber being axially transposable toward the transfer chamber to create, in cooperation with the ledge and article-bearing stage, a sealable enclosure about articles positioned on the stage, the enclosure having a selectively evacuable volume in fluid isolation from the loading chamber and the transfer chamber to allow ambient atmospheric pressure and high vacuum pressure to coexist in the loading chamber and the selectively evacuable volume, respectively.

2. The apparatus of claim 1, further comprising a high vacuum processing system access chamber in communication with the transfer chamber.

3. The apparatus of claim 1 in which the article chamber is modularly devised such that the loading chamber is removably interconnected with the transfer chamber and the loading chamber is adapted to interconnect with a third chamber to expand the loading chamber volume.

4. The apparatus of claim 1 in which the ledge and article-bearing stage cooperate with an O-ring to create the fluid isolation between the loading and transfer chambers.