利用CMOS-MEMS與化鎳浸金技術製作MEMS邏輯閘

Abstract

以往的機械式邏輯閘大多數是以MOS-like開關，藉由數個同樣結構串並聯來達到邏輯功能。但如此一來會增加佈局面積、降低良率。本篇文章提出兩種設計，以TSMC 0.35μm 2p4m CMOS-MEMS標準製程，製作出單一機械結構，且具有NAND跟NOR的邏輯功能：雙層式微機電邏輯閘、梳狀制動器微機電邏輯閘。 此外，金屬與金屬接觸問題是微機電開關與微機電邏輯閘的重要成敗因素之一，接觸金屬的壽命直接影響了元件的可靠度，本文亦提出了兩個技術來改善微機電中的金屬與金屬接觸問題：TSMC製程中的TiN、化鎳浸金(Electroless Nickel and Immersion Gold: EN/IG)。 TiN有著高熔點、高硬度、導電性、耐磨耗等等優點，很適合拿來做為接觸用金屬。TSMC製程中，金屬層上下個會有一層TiN，假如能夠使用TiN來當做接觸金屬，不僅能減少一道額外的製程，更能增加良率。 化鎳浸金技術在現在的工業上已經發展的相當成熟完善，普遍被用於金屬與合金的表面加工。化鎳浸金的特點之一便是不需要外加電極，減少許多不必要的麻煩。

This paper presents the design and fabrication of a MEMS logic gate that can perform either NAND gate or NOR gate functions using the same mechanical structure, but different electrical interconnects. Two designs which are two-layer MEMS logic gate and comb driver MEMS logic gate and both fabricate by TSMC 0.35μm 2P4M CMOS-MEMS process. The metal-to-metal contact of MEMS switch and MEMS logic gate is one important factor in the success or failure, directly affects the reliability of components.Two methods are then proposed to tackle this problem. One uses titanium nitride (TiN) as the contact material, the other one uses “electrode-less nickel and immersion gold (ENIG)” to deposit gold film on top of aluminum. Both methods are underway and partial success has been observed from experimental data.