Study of oxidation mechanisms in Ge and SiGe

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H02331
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Electronic materials/Electric materials
• Research Institution: The University of Tokyo
• Principal Investigator: Toriumi Akira 東京大学, 大学院工学系研究科(工学部), 教授 (50323530)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 酸化機構 / ゲルマニウム / シリコン・ゲルマニウム / Deal-Grove モデル / 同位体酸素 / 界面

Outline of Final Research Achievements

We have demonstrated new experimental results concerning the oxidation mechanism of SiGe and Ge through this Kiban-kenkyu. It has been experimentally elucidated that the oxidation of Ge is significantly different from that of Si in terms of oxidant species. O2 diffusion is the main contribution in case of Si, as described by the Deal-Grove model but is atomic O in case of Ge. Furthermore, the oxygen diffusion inside GeO2 film is significantly suppressed under high-pressure O2. It is also clarified that the oxidation of SiGe is different from Si or Ge, and the reaction scheme changes with oxidation. The result is related with a difference of thermodynamic stability between SiO2 and GeO2. Once SiO2 is formed on SiGe, Ge in SiGe is not actually oxidized anymore. This should be considered in SiGe oxidation.
Precise process control based on these fundamental considerations is required in order to achieve high performance Ge and SiGe gate stacks.

Free Research Field

半導体材料工学

Academic Significance and Societal Importance of the Research Achievements

SiGeおよびGe はSiにかわる次世代半導体材料として世界的に期待されている．しかしこれらの材料の界面制御がきわめて難しいことが広く認識されている．界面特性の制御は半導体デバイスにおいてもっとも重要な要素技術であり，我々はそれぞれの酸化機構を明らかにするという観点から本研究を推進した．結果として両材料ともSiとは酸化機構がきわめて異なることが実験的に明らかになり，このことを理解して界面を形成することによって両材料ともに極めて良好なMOS界面特性を示すことが実証された．これらの成果は材料科学的に大きな意義があることは言うまでもなく，次世代半導体デバイス開発にむけて世界的に意義が大きい．