Contact resistance study of noble metals and alloy films using a scanning probe microscope test station
Contact resistance study of noble metals and alloy films using a scanning probe microscope test station
复制标题
DOI：
10.1063/1.2785951
复制
发表时间：
2007-10-01
影响因子：
3.2
通讯作者：
Adams, G. G.
中科院分区：
文献类型：
--
作者：
Chen, L.;Lee, H.;Adams, G. G.
电接触材料的选择是设计金属接触微机电系统（MEMS）开关的关键步骤之一。理想情况下，触头应具有非常低的接触电阻和高耐磨性。不幸的是，这种组合不能用目前在宏开关中使用的接触材料容易地实现，因为在微动开关中可用的接触力通常不足以（小于1 mN）穿透非导电表面层。作为材料选择过程中的一个步骤，将三种贵金属铂（Pt）、铑（Rh）、钌（Ru）及其与金（Au）的合金作为薄膜沉积在硅（Si）衬底上。使用专门开发的扫描探针显微镜测试站测量这些材料的接触电阻及其随循环的演变。然后将这些结果与材料硬度和电阻率的测量结果进行比较。与Au合金化的贵金属的初始接触电阻大致与它们的电阻率成比例。在室内空气环境中，在200-250 μ N的接触力下，测量不同金属膜在循环期间的接触电阻。有人发现，接触电阻随着循环与低浓度的金，由于在接触上的污染物的积累的合金膜增加。然而，对于具有高金含量的合金膜，由于污染而导致的接触电阻增加直到10（8）次循环是不显著的。这些观察结果表明，Rh，Ru和Pt及其低金含量的金合金作为MEMS开关中的接触材料容易发生污染故障。(C)2007年，美国物理学会。
The proper selection of electrical contact materials is one of the critical steps in designing a metal contact microelectromechanical system (MEMS) switch. Ideally, the contact should have both very low contact resistance and high wear resistance. Unfortunately this combination cannot be easily achieved with the contact materials currently used in macroswitches because the available contact force in microswitches is generally insufficient (less than 1 mN) to break through nonconductive surface layers. As a step in the materials selection process, three noble metals, platinum (Pt), rhodium (Rh), ruthenium (Ru), and their alloys with gold (Au) were deposited as thin films on silicon (Si) substrates. The contact resistances of these materials and their evolution with cycling were measured using a specially developed scanning probe microscope test station. These results were then compared to measurements of material hardness and resistivity. The initial contact resistances of the noble metals alloyed with Au are roughly proportional to their resistivities. Measurements of contact resistance during cycling of different metal films were made under a contact force of 200-250 mu N in a room air environment. It was found that the contact resistance increases with cycling for alloy films with a low concentration of gold due to the buildup of contamination on the contact. However, for alloy films with a high gold content, the contact resistance increase due to contamination is insignificant up to 10(8) cycles. These observations suggest that Rh, Ru, and Pt and their gold alloys of low gold content are prone to contamination failure as contact materials in MEMS switches. (C) 2007 American Institute of Physics.