Method of profiling compensator concentration in semiconductors
US5103183A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 26, 1990 |
| Grant date | Apr 7, 1992 |
| Priority date | — |
| Expiry date | Jan 26, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R31/2603
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method is provided for making cryogenic capacitance-voltage (C-V) measurements of semiconductor epitaxial layers without the need for measuring fully processed devices. The method utilizes impurity hopping conduction to obtain a compensator concentration profile. In a preferred embodiment, a metal electrode is evaporated onto the bottom of the substrate of a semiconductor wafer having a heavily doped substrate, a heavily doped epitaxial layer, and an undoped epitaxial layer. A mask is used to form metal electrode capacitor dots on the top of the undoped layer. The cryogenic C-V measurement system comprises a Helitran dewar with a wafer holder and electrical connections, a temperature controller, measurement electronics, and a microcomputer. A programmable dc source is stepped and combined with an ac voltage supplied by a lock-in amplifier. A preamplifier converts the current from a capacitor electrode on the wafer to a voltage measured by a lock-in amplifier. The wafer output is processed by phase sensitive detection in the lock-in amplifier. The C-V measurements are controlled by the microcomputer during automatic progression through the voltage steps. Compensator concentration …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.