公开(公告)号：US3590372A

公开(公告)日：1971-06-29

申请号：US3590372D

申请日：1968-12-26

Applicant: IBM

Inventor： DESANTIS DOMINIC P ,  DESSAUER RALPH G ,  GOREY EDWARD F ,  POPONIAK MICHAEL R ,  SCHNEIDER CHRISTIAN P ,  SCHUMANN PAUL A JR

IPC: G01R27/00 ,  G01N27/04 ,  G01R1/067 ,  G01R31/28 ,  H01L21/66 ,  G01R27/14

CPC classification number: G01R31/2831 ,  G01N27/041 ,  G01R1/06705

Abstract: A three-point probe is employed to determine the spreading resistance of a material with the spreading resistance probe, which is common to both the current source and a voltage measuring means, being moved into engagement with the material after the other two probes are in engagement with the material. The velocity with which each of the probes engages the material is controlled and is variable. To ascertain that a good contact has been made by the spreading resistance probe and the magnitude of the current flowing through the material from the current source, the voltage measuring means is connected across resistance means in the wire from the current source to the spreading resistance probe and current is directed through the resistance means in opposite directions by flowing through the material between the spreading resistance probe and one of the other two probes. After the magnitude of the current has been determined, the voltage measuring means is connected to the spreading resistance probe adjacent its contact to the material and to the other of the two probes, which is not connected to the current source, to determine the voltage drop through the material due to current from the current source flowing in opposite directions through the material. The amount of difference between the two voltage readings on the specimen indicates if good contact is achieved.