Ion-assisted Si/XeF2 etching: Temperature dependence in the range 100–1000 K

Abstract

The Ar+-ion enhanced Si(100)/XeF2 reaction is studied in a multiple beam setup for silicon temperatures from 100 K up to 1000 K. The XeF2 flux is 2.7 monolayers/s and the Ar+ flux 0.033 monolayers/s at an energy of 1000 eV. Both the XeF2 consumption and the SiFx production are measured by mass spectrometry. The enhancement of the etch rate peaks around 250 K as is observed in both the XeF2 and SiFx signals. The gradual decline above 250 K is attributed to a diminished surface fluorination and XeF2 precursor concentration. The dropoff below 250 K is presumably caused by sputtering of the XeF2 precursor, as is concluded from the temperature dependence of the XeF+/XeF2+ signal ratio. Around 175 K this decrease is so strong that the ions seem to no longer enhance, but rather reduce, the etch rate. Below 150 K the ions are driving the etch process. In this range the spontaneous process is blocked by XeF2 condensation, but the ion-assisted process continues due to sputtering or dissociation of the condensate.

Guidelines for etching silicon MEMS structures using fluorine high-density plasmas at cryogenic temperatures

“…The inhibitor layer is created by oxygen radicals from the plasma via the formation of a SiO F deposit [9]. Cooling the wafer to cryogenic temperatures enhances passivation by reducing the chemical reactivity, which can be explained by a reduction in the volatility of reaction product SiF [11], [12]. However, SF decomposition also produces ions like SF that enhance etching of the SiO F layer locally as they strike the surface with relatively low kinetic energies.…”

Microfabrication of Si-Based High-Index-Contrast-Grating Structure by Thermal Nanoimprint Lithography and Cl2/Xe-Inductively Coupled Plasma Etching

“…On the other hand, low-temperature etching is also widely used in Si dry etching. [19][20][21][22] However, the dry etching process for a III-V compound semiconductor such as GaAs and InP used in the VCSEL structure is performed at a relatively high temperature. [23][24][25][26][27] It would be convenient if the same system could be available for the dry etching process of both the III-V compound semiconductor and Si.…”

Inductively Coupled Plasma Etching of Silicon Using Solid Iodine as an Etching Gas Source

“…In the fabrication of micro-electro-mechanical systems (MEMS), the switched process, known as the Bosch process, using SF 6 /C 4 F 8 or a low-temperature etching process using Cl 2 or SF 6 is generally used. [1][2][3][4] However, in the switched process using SF 6 /C 4 F 8 , undesirable products, such as a polymeric layer, are deposited on the etched surface and sidewall. Therefore, in the etching process without carbon, carbon fluoride is required to obtain a clean surface.…”