MEMS Active Probe for Wafer-level Switching Contacter

本研究的目的是提出一种新的IC探针卡，它由执行器集成的MEMS探针组成，可以直接切换触点。此外，我们已经尝试开发基本的制造工艺来实现它。具体来说，我们研究了摩擦接触过程，这是一种电击穿，是使用MEMS探头与Al衬垫进行低力接触所不可缺少的。重要的结果如下1。利用新开发的测量系统对摩擦接触特性进行表征我们实现了力分辨率为10 μN的摩擦接触特性测量系统，并测量了几种探针与Al和Cu衬垫冶金膜之间的接触特性。(1)接触电阻随最大熔滴电流的增大而减小，最大熔滴电流由熔滴电压和电路电阻决定。(2) Ni探针在传统探针中具有最低的接触电阻。当极限电流大于100ma时，即使接触力在10μN.2左右，电阻也可以小于1 Ω。电镀镍微悬臂探头的发展利用电镀镍双层内应力的差异，提出了一种微机械镍卷曲悬臂探头，并开发了其制造工艺。下部低应力层采用salfamic酸浴，上部高应力层采用Watts浴，成功地获得了约400mpa的内应力差。通过测量制备的Ni微悬臂探针的弹簧常数为计算值的70%，证明了Ni微悬臂探针可以应用于衬垫间距小于20 μm的集成电路测试，并且其摩擦特性与传统针探针相当。

The purpose of this stude is to propose the new IC probe card which consists of actuator-integrated MEMS probes and enables the direct switching of contacts. Also, we have attempted to develop basic fabrication processes to realize it. Specifically, we have studied the fritting contact process which is a kind of electrical breakdown and is indispensable to make contact to Al pads with low forces using the MEMS probe. The important results are described below.1. Characterization of fritting contact using newly developed measurement systemsWe have realized the systems which can measure the fritting-contact characteristics with the force resolution of 10 μN and measured the characteristics of the contacts between several kinds of probes and pad metallurgy films of Al and Cu.(1) Contact resistance decreases with increasing the maximum fritting current determined by the fritting voltage and circuit resistance.(2) Ni probe can have lowest contact resistance among the conventional probes. When the limit current is larger than 100 mA, the resistance can be smaller than 1 Ω, even if the contact force is around 10μN.2. Development of electroplated Ni microcantilever probesWe have proposed the micromachined Ni curl-up cantilever utilizing the difference of internal stress in electroplated Ni double layers and developed its fabrication process. The internal stress difference of about 400 MPa has successfully been obtained utilizing a salfamic acid bath for the lower low-stress layer and a Watts bath for the upper high-stress layer.We have demonstrated that the Ni microcantilever probes can be applied to the test of IC with the pad pitch of less than 20 μm, by measuring the spring constant of the fabricated microprobes as 70 % of calculated value and showing their fritting characteristics are comparable to those of the conventional needle probes.