具有用于多値逻辑应用的多层鳍部之鳍式场效电晶体及其形成方法;FINFET WITH MULTILAYER FINS FOR MULTI-VALUE LOGIC (MVL) APPLICATIONS AND METHOD OF FORMING

摘要

本发明揭露一种形成具有小占用面积之多值逻辑电晶体及所得到之装置的方法。实施例包括于矽基板上形成复数个鳍片，各该鳍片以硬遮罩覆盖；以氧化物填充该鳍片与该硬遮罩之间的空间；移除该硬遮罩且使各该鳍片凹陷，在各鳍片上方的该氧化物中形成凹穴；在各该凹穴中形成复数层矽基底(Si-based)层，该些矽基底层具有从底层到顶层逐渐增加的锗(Ge)或碳(C)含量的比例或逐渐减少的掺杂物浓度；对该些鳍片之顶部进行化学机械研磨以达到平坦化；使该氧化物凹陷到稍微低于该鳍片顶部的深度，且该鳍片之厚度相等于各矽基底层之厚度；以及于该复数层矽基底层之上形成高k闸极介电及金属闸极电极。; fillmg spaces between the fins and hard masks with an oxide; removing the hardmasks and recessing each fin, forming a cavity in the oxide over each fin; forming plural Si-based layers in each cavity with an increasing percentage of Ge or C or with an decreasing concentration of dopant from a bottom layer to a top layer; pelforming CMP for planarization to a top of the fins; recessing the oxide to a depth slightly below a top portion of the fin having a thickness equal to a thickness of each Si”; and forming a high-k gate dielectric and a metal gate electrode over the plural Si-based layers.