半导体器件测试设备中的微弱电流测量模块设计

Design on weak current measuring module in semiconductor test equipment

在半导体测试中,需要测量μA～pA级的微弱电流,而且测量时检流计有多种可能的接入方式。为适应电流测量范围并实现接入方式的灵活性,设计了一种微弱电流检测模块,它基于低偏置电流的互阻放大器,由单片机实现A/D转换和自动量程选择,采用信号与电源分别隔离的方式实现可变的接入方式,并采取了多项措施提高精度、保护模块。该模块实现了10 pA的分辨能力和0.1%的量程内积分非线性,已经达到半导体测试设备中电流检测范围和精度的要求,并有望运用于光电测量、核电子测量等其他微弱电流检测领域。

Weak current with the magnitude of μA -- pA is usually measured in semiconductor testing, and measuring methods may include several possible current meter connecting ways. A kind of weak current measuring module is developed for adapting the current measurement range and the flexibilities of connections. The module is designed based on a low bias current transimpedance amplifier. A microcontroller in the module is used for A/D converting and auto range selection. Signal and power supply isolation is designed for variable connections. Several special steps are taken for improving the precision and protecting the module. 10pA resolution and 0.1% INL have been finally realized for the requirement of the target semiconductor testing device. The weak current measuring module could also be used in other fields such as photoelectric measurement and nuclear electronics measurement.