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Low Temperature Plasma Anodization

IP.com Disclosure Number: IPCOM000079228D
Original Publication Date: 1973-May-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

O'Hanlon, JF: AUTHOR [+2]

Abstract

The efficiency of a plasma anodization process is improved by trapping low-energetic electrons. In the anodization chamber a ring electrode or grid of thin wires is arrange in the vicinity of the metal wafer. That electrode is biased positively with respect to the plasma. Thus "cold" electrons are absorbed and the higher energetic electrons are trapped in a potential well of considerable extent, so that the anodization process is speeded up.

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Low Temperature Plasma Anodization

The efficiency of a plasma anodization process is improved by trapping low- energetic electrons. In the anodization chamber a ring electrode or grid of thin wires is arrange in the vicinity of the metal wafer. That electrode is biased positively with respect to the plasma. Thus "cold" electrons are absorbed and the higher energetic electrons are trapped in a potential well of considerable extent, so that the anodization process is speeded up.

A metal anodization chamber is pumped down to high vacuum and some oxygen is admitted. An insulated sample holder is surrounded by a ring cathode being at a negative potential of about 600 to 900 volts. Metal block 1 carries substrate wafer 2 with the sample film on it. Electrostatic shield 3 covers the arrangement. Metal block 1 is biased to a certain positive potential, and it is maintained at a desired temperature by monitoring a heater element with the aid of a thermocouple. The thickness of the oxide grown is controlled by varying the block bias.

The higher energy electrons in the plasma ionize oxygen in the plasma or ionize the oxygen upon the surface of the metal sample. The greater the ratio of hot electrons to cold electrons in the plasma, the more numerous will be the number of oxygen ions to combine with the metal sample, and the faster the anodizing process will proceed.

Electrode 4 is either a grid of fine platinum wires or a single turn of such wire, about 0.001" in diameter....