一种精确测量MOSFET晶圆导通电阻的方法

A Skillful Technology for Low MOSFET R_(DS(on)) Testing

导通电阻的准确测量是低导通电阻MOSFET晶圆测试中的一个难点。要实现毫欧级导通电阻的测试,必须用开尔文测试法;但实际的MOSFET晶圆表面只有两个电极(G、S),另外一个电极(D)在圆片的背面,通常只能将开尔文的短接点接在承载圆片的吸盘边缘,无法做到真正的开尔文连接,由于吸盘接触电阻无法补偿而且变化没有规律,导致导通电阻无法精确测量。介绍了一种借用临近管芯实现真正开尔文测试的方法,可以实现MOSFET晶圆毫欧级导通电阻准确稳定的测量。

It is difficult to measure low RDS （on） of MOSFET exactly in wafer testing （CP） . It is necessary to use Kelven connections for testing resistor whose resistance is lower than several milliohms. Actually, for MOSFET wafer, there are only 2 pads （G and S） which can be connected in Kelvin connections on the wafer surface. The third pole （D） is on the bottom of wafer, can only connect to edge of the chuck which hold the wafer in the course of CP, can＇t achieve really Kelvin connections for MOSFET wafer testing in normal way. As the connect status for wafer and chuck is unstable, the testing result is unstable too. The paper presents a way to carry really Kelvin connections for MOSFET wafer testing by using a nearby DIE which is turned on. By this way, RDS （on） lOW than several milliohms can be measured exactly and stably.