Electrochemically controlled shaping of semiconductors
Abstract
Abstract A METHOD FOR SELECTIVELY ETCHING A SEMICONDUCTOR PARTICULARLY APPLICABLE TO PRECISION THINNING OF SILICON INTEGRATED CIRCUIT WAFERS. THE SEMICONDUCTOR AND A CATHODE ARE INSERTED IN AN ELECTROLYTE WHICH ETCHES THE SEMICONDUCTOR IN THE ABSENCE OF APPLIED VOLTAGE TO THE CATHODE, AND ALL OF THE SEMICONDUCTOR PORTIONS, WHICH ARE AT A POTENTIAL LESS THAN SOME PASSIVATION POTENTIAL, ARE ETCHED AWAY. THOSE SEMICONDUCTOR PORTIONS WHICH ARE AT A POTENTIAL GREATER THAN THE PASSIVATION POTENTIAL ARE NOT ETCHED. IN PRACTICE, A SUITABLE VOLTAGE DIFFERENTIAL (ABOVE AND BELOW THE PASSIVATION POTENTIAL) CAN EXIST ACROSS A PN JUNCTION, SO THAT THE ETCHING STOPS AUTOMATICALLY AT A JUNCTION THE LOCATION OF WHICH CAN BE ACCURATELY PREDETERMINED. ALTERNATIVELY, SERIES RESISTANCE CAN BE USED TO PROVIDED A SUITABLE VOLTAGE DIFFERENTIAL ACROSS PRESELECTED PORTIONS OF A SEMICONDUCTOR BODY. FOR SILICON, THE PASSIVATION POTENTIAL IS ABOUT 0.5 VOLT WHERE THE ELECTROLYTE IS POTASSIUM HYDROXIDE IN EQUILIBRIUM WITH AIR AND THE CATHODE IS PLATINUM.
Inventors
- 👤 Herbert A Waggener
Bibliographic Details
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