Chemistry: electrical and wave energy – Processes and products – Electrostatic field or electrical discharge
Patent
1992-10-21
1994-04-05
Valentine, Donald R.
Chemistry: electrical and wave energy
Processes and products
Electrostatic field or electrical discharge
2041293, 20412975, 2041297, C25F 312, C25F 330
Patent
active
053002008
ABSTRACT:
The accuracy of electrochemical profiling measurements that provide depth dependent characteristics for a semiconductor is enhanced by stabilizing the semiconductor's effective dissolution valence. According to the present invention, the semiconductor dissolution valence is stabilized by anodically dissolving the semiconductor surface using a potential associated with the electropolishing region of the semiconductor. This potential, typically 1V to 5V relative to the profiler saturated calomel reference electrode, favors quadrivalent dissolution over divalent dissolution. Dissolution valence is further stabilized by using an electrolyte having a relatively low fluoride content, a characteristic associated with a low dissolution rate (relative to a rate of electrochemical oxidation) of the oxide at the semiconductor surface. Preferably the electrolyte has a fluoride content in the approximate range 0.01 mol-dm.sup.-3 to about 1.0 mol-dm.sup.-3, and is buffered with a pH ranging from about 3 to 5. According to the present invention, the effective dissolution valence of silicon is stabilized to about 3.70, and craters etched in a silicon specimen will have a deviation from a mean profile depth within about .+-.1%.
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Semiconductor Physics Laboratory RT
Valentine Donald R.
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