Formation of High Aspect-Ratio Ge-Fin Structures with {110} Facets by Anisotropic Wet Etching

Moriyama, Yoshihiko; Ikeda, Keiji; Kamimuta, Yuuichi; Tezuka, Tsutomu

doi:10.1149/1.3487572

Cited by 8 publications

(5 citation statements)

References 4 publications

(7 reference statements)

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“…Angle between straight sidewall and wafer surface was measured to be 54.7 degrees, as shown in Figure 1d and Figure S2, which corresponds well to the angle between Ge(100) and Ge(111). 32 As a result, at the early stage of Ge MacEtch, the top-down etching process is anisotropy, leading to the formation of sidewalls with (111) facets. However, with prolonged etching time, bottom part (Zone II) showed slightly different etching behaviour with top part since sidewall in Zone II was arc-shape.…”

Section: Macetch Formation Of Ge Inverted Pyramid Arraymentioning

confidence: 99%

A highly ordered and damage-free Ge inverted pyramid array structure for broadband antireflection in the mid-infrared

et al. 2021

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Section: Macetch Formation Of Ge Inverted Pyramid Arraymentioning

confidence: 99%

A highly ordered and damage-free Ge inverted pyramid array structure for broadband antireflection in the mid-infrared

et al. 2021

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“…[33,34] We believe when TiN was used as the catalyst, higher etching rate of (100) than (110) facet was realized. Etching rate dependence of exposed Ge sidewalls has been previously reported by Moriyama et al [35] using NH 4 OH/H 2 O 2 / H 2 O (APM) solution realized by tuning pH. Etch rate dependence of sidewall orientation has also been observed in InP i-MacEtch, [23] which was attributed to the mitigation of crystallographic etching when etch rate is high enough.…”

Section: Resultsmentioning

confidence: 60%

Producing Microscale Ge Textures via Titanium Nitride‐ and Nickel‐Assisted Chemical Etching with CMOS‐Compatibility

Liao

Shin

Jin

et al. 2021

Adv Materials Inter

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on Ge has been explored as a promising alternative to traditional etching techniques. For example, Kim et al. [9] employed a thin Au layer as catalyst to realize pyramidal and indentation antireflection textures on Ge which contributed to enhance responsivity of near infrared (NIR) photodetectors. Lee et al. [10] coated a thin Ag layer on Ge and realized the formation of random antireflection structures by MacEtching in H 2 O 2 /HF/AgNO 3 solution. Shin et al. [11] also fabricated Ge nano-cone array using a thin Ag catalyst layer, followed by MacEtching in HF/H 2 O 2 .It should be emphasized that metal catalyst layer such as widely-used Au and Ag plays a crucial role for the MacEtch process of Ge, since it catalyzes the reduction of oxidant in the solution (normally H 2 O 2 and KMnO 4 ) to generate holes for subsequent etching. Although MacEtch of Ge based on those noble metal catalysts has been well explored, the usage of those noble metals is still a major drawback for the integration of Ge MacEtch in the current industrial front and back end of the line in the complementary metal oxide semiconductor (CMOS) fabrication process because deep-level defects are generated by non-CMOS compatible metals. [12][13][14] Many researchers have delved into the uncharted territory in order to identify the suitable CMOS-compatible catalyst for Ge MacEtch. For example, Li et al. [15] investigated the formation of Ge nanostructures by wet etching assisted by graphene. Nakade et al. [16,17] employed reduced graphene oxide to boost Ge wet etching in water. However, graphene-and graphene oxide-assisted chemical etching of Ge suffer from low etch rate (20-30 nm h −1 even when heated up) and poor morphologies, which make it unsuitable for mass production of uniform nanostructures. Therefore, it is worthwhile to explore novel etching catalysts with high efficiency and CMOS-compatibility.Titanium nitride (TiN) is widely used in CMOS process as local interconnects and barrier layers because it is chemically stable, [18] highly conductive, and has a work function of 4.5 eV. [19] These properties make it also suitable as the catalyst which can boost various chemical reactions. [20,21] As the pioneering work employing TiN as catalyst in wet etching, Kim et al. [22] have proven its effectiveness in the fabrication of highly ordered Si nanopillars. However, etching characteristic of TiN-MacEtch is different when compared with typical Au-MacEtch. Mass transport underneath the TiN is significantly limited due to its strong adhesion, leading to etching in area not covered by TiN, similar As an emerging anisotropic wet etching technique, metal-assisted chemical etching (MacEtch) has been widely employed for fabricating nano-and micro-structures of germanium (Ge) for potential infrared (IR) photonics and optoelectronics. However, traditional noble metal catalysts such as Au and Ag limit its application in complementary metal oxide semiconductor (CMOS) processes, as Au is considered as a detrimental deep-level impurity in Ge. In this work, the fe...

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“…It is known that the H2O2 present in the chemical solution oxidizes the Si surface and that the oxidized Si is simultaneously etched by HF [4]. And H2O2 is known not to etch Si, but it etches the oxidized Ge [5]. Diluted ammonia (NH4OH, 0.02 M) at ECS Transactions, 92 (2) 13-19 (2019) room temperature was also evaluated.…”

Section: Etching Chemistry For Ge Residue Cleaning In Simentioning

confidence: 99%

Study of Si Nanowire Surface Cleaning

Iwahata¹,

Yoshida²,

Komori³

et al. 2019

ECS Trans.

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The Gate-All-Around (GAA) Field-Effect-Transistor (FET) is proposed as a promising candidate to replace Fin FET. In GAA architecture, Si Nanowires (NWs), which are fabricated by selective etching of SiGe from Si/SiGe multilayer fin structure, are used as channel. One of the concerns for fabricating GAA architecture is residual Ge, which is diffused SiGe from the Si/SiGe multilayer stack, in the Si NWs after their release. This Ge residue is a concern, since it could cause a degradation in device performance. The roughness of the Si NWs’ surface, which is a further factor in the degradation of device performance, was also examined. In this study, residual Ge removal and surface roughness with commodity chemistry was investigated. Finally, it was confirmed that residual Ge could be completely removed from Si without increasing Si surface roughness by dH2O2.

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Formation of High Aspect-Ratio Ge-Fin Structures with {110} Facets by Anisotropic Wet Etching

Cited by 8 publications

References 4 publications

A highly ordered and damage-free Ge inverted pyramid array structure for broadband antireflection in the mid-infrared

A highly ordered and damage-free Ge inverted pyramid array structure for broadband antireflection in the mid-infrared

Producing Microscale Ge Textures via Titanium Nitride‐ and Nickel‐Assisted Chemical Etching with CMOS‐Compatibility

Study of Si Nanowire Surface Cleaning

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