Browse Prior Art Database

New Design of Cryogenic-Temperature Cathode for Plasma Reactors

IP.com Disclosure Number: IPCOM000120198D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 55K

Publishing Venue

IBM

Related People

Lee, YH: AUTHOR [+2]

Abstract

The present invention discloses new design of the substrate which operates at low temperatures down to the liquid nitrogen cryogenic temperature (77~K).

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New Design of Cryogenic-Temperature Cathode for Plasma Reactors

      The present invention discloses new design of the substrate
which operates at low temperatures down to the liquid nitrogen
cryogenic temperature (77~K).

      The electrode consists of two parts, the top portion of a
cathode cooled by liquid nitrogen and the bottom portion maintained
at room temperature by water circulation.  A self-pumping vacuum
jacket ensures thermal isolation between these two parts of extremely
different temperatures.  Wafers sit on the top part of the electrode
during reactive ion etching, in order to maintain a wafer temperature
at 77~K. Also, pre-cooled helium gas, replacing liquid nitrogen, may
achieve various temperatures above 77~K, if one desires. The vacuum
jacket is connected to the reactor chamber through an electrically
controlled valve which opens whenever the main chamber is at a high
vacuum below 10-6 Torr and closes only when a plasma process starts
at high pressures.  This self-pumping vacuum jacket is an integral
part of the cryogenic electrode and liquid nitrogen transport lines.
Although a separate pumping unit can be directly connected to the
vacuum jacket, the self-pumping feature is superior in the sense that
the human error can be avoided particularly in the manufacturing
environment.  A use of ceramic-sealed tubing for liquid-nitrogen
transport lines electrically isolates the valve from the RF powered
electrode.

      Thermal conduction from...