Mercury Probe Cv Tester Measurement Of Silicon Heavily Doped Substrate Epitaxial Layer Resistivity Of Accuracy And Stability

The paper study the problem that, when the company were to use mercury-probe CV495 Measurement testing heavily doped silicon epitaxial layer resistivity, we found the results have an unstable situation, leading to a large number of products discarded. First, we analysis various factors of affect the stability and repeatability of test results; through testing, found that:1. Mercury metal replacement, will make the results of resistivity volatility within about 1 day and then gradually stabilized.2. After surface treatment the resistivity of calibration wafer will be experienced from low to high in a process of change within about 1 day, then to be followed stabilized.3. About the time of treatment by CrO3, we found if time is too short below 10 minutes, it will make a poor quality oxide layer wafer leakage, and affect the level of the test curve and resistivity value correctness.Combination of the above 3 points, we can build a more complete way to monitor the mercury probe CV testing heavily-doped wafer, based on the original CV:1. To establish a series calibration wafer of known resistivity, for the calibration of effective mercury contact area. And periodic testing of the calibration wafer resistivity to monitor the stability of CV tester. When the calibration wafer resistivity beyond the prescribed range, and no other factors have an impact on their circumstances, should amend the effective mercury contact area.2. Periodic replacement of mercury metal (now set for a change per a month), the calibration of mercury contact area must begin after the replacement more than half a day.3. Regularly surface treatment (set for a time per a month), the calibration wafer resistivity will take more than half a day after restored to the original nominal value. the effective area of the calibration is advisable within this half-day of resistivity recovery.4. The relationship between epitaxial resistivity and doping dose in process, can help us to find the changes in doping dose caused by possible offsets of CV meter. If there is CV test offset doubts, you can check the CV test systems, test calibration wafer, cleaning them, even the replacement of mercury metal.This study has been verified through the actual production and is used in production, has achieved good efficiency.