A Novel MEMS Probe for LSI Testing

The rapid microminiaturization of LSI chips has encouraged the need for similarly microminiaturizing the probes of probe cards, the parts used to inspect IC chips. In response to this need, a method of producing 3-dimensional microprobes is devised by lithography and electroforming method. By examining and optimizing each part of the process, we produced a 3-dimensional microprobe with the desired shape. The pitch of this micro probes are 24 mum (straight type) and 20 mum (staggered type). The straight type micro probe dimensions are 15 mum in width, 40 mum in thickness, 1000 mum in length, 15 mum in tip thickness, and 10 mum in tip diameter. The staggered type micro probe dimensions are 30 mum in width, 40 mum in thickness, 1000 mum in length, 15 mum in tip thickness, and 15 mum in tip diameter, respectively. And the micro probe height is 155 mum. The mechanical and electrical properties of the microprobe were estimated by measuring the contact force and contact resistance. The measurement showed satisfactory results: the contact force allowed a displacement magnitude as large as 40 mum, accompanied by a satisfactory contact force of 7 mN. In addition, the contact resistance exhibited low and stable values when contact was formed on an object made of Au exhibiting a contact force of 1 mN or more, demonstrating the high potential of the prototyped microprobes.