Investigation on Morphology and Thermal Stability of NiGe Utilizing Ammonium Fluoride Pretreatment for Germanium-Based Technology

Abstract

In this letter, a novel ammonium fluoride pretreatment (AFP) method has been proposed to improve the morphology and thermal stability of NiGe on bulk germanium devices. The root mean square roughness of NiGe film has been obviously decreased using the AFP method, indicating more smooth and flat NiGe surfaces formed compared with samples by hydrochloric acid and hydrofluoric acid pretreatments. Also, the thermal stability of NiGe film has been enhanced, since uniform NiGe film can be formed at temperature as high as 600 • C. In addition, NiGe/n-Ge Schottky diodes have been fabricated to illustrate the benefits of AFP method in Ge-based devices. Better rectifying performance has been achieved using the AFP method from the benefit of suppressing reverse current about one order of magnitude, compared with the hydrochloric acid treated sample. Thus, both the material properties and electrical characteristics of NiGe film have been effectively improved by the simple AFP technique, revealing its potential for Ge-based process technology.

Low Electron Schottky Barrier Height of NiGe/Ge Achieved by Ion Implantation After Germanidation Technique

“…The diode areas were defined by the conventional lithography and etching. Then, the wafers were pretreated with ammonium fluoride pretreatment (AFP) method [15], and 20-nm Ni was sputtered on it, followed by a rapid thermal annealing at 400 • C in nitrogen ambient to form the NiGe film. The unreacted Ni was removed by HCl/H 2 O solution.…”

Ultrathin NiGe Films Prepared via Catalytic Solid–Vapor Reaction of Ni with GeH4

“…Previously, NiGe films were targeted, as contact materials, for Ge-based technology, and therefore, the synthetic strategy included solid state thermal reaction of PVD Ni films with different Ge substrates (amorphous, epitaxial, or polycrystalline). ,− A majority of the studies were focused on the synthesis of thicker NiGe films (50–100 nm) on small sample substrates. ,,− Though the NiGe system is less studied, it displays a complexity similar to that of silicide systems. It is well know that controlling the stoichiometry, composition, and crystallographic phase of metal–silicides and −germanides is rather difficult due to the complex phase formation behavior .…”

Non-Silicon microelectronics: Germanium and Germanium-Tin field-effect transistors

“…结工程 [63,69] 、应变工程及全耗尽沟道技术等提高器件 的工作电流. 表 2 Γ和L点材料能带计算相关参数 [64][65][66][67] 进行这方面的研究, 在Ge与GeSn材料生长 [70] 、表面钝 化 [71][72][73][74] 、源漏工程 [75,76] 、应变GeSn pMOSFET [39,[74][75][76] ,…”

“…提出了氟化铵表面预处理NiGe方法 [75] , 有效提高了器 件的热稳定性和电学性能, 研究了锑和磷的共注入, 可提高n型掺杂浓度 [76] . 中国科学院半导体研究所在 国内率先开展了IV族材料外延生长的研究工作, 研制 出了具有国内领先、国际先进水平的Ge和GeSn材料, 包括Si衬底上Ge和GeSn、Ge衬底上应变GeSn、SOI 上压应变Ge及GeOI, 这些材料方面的研究为FET器件 的研制奠定了夯实的基础.…”