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Title: Morphology and chemical termination of HF-etched Si{sub 3}N{sub 4} surfaces

Abstract

Several reports on the chemical termination of silicon nitride films after HF etching, an important process in the microelectronics industry, are inconsistent claiming N-H{sub x}, Si-H, or fluorine termination. An investigation combining infrared and x-ray photoelectron spectroscopies with atomic force and scanning electron microscopy imaging reveals that under some processing conditions, salt microcrystals are formed and stabilized on the surface, resulting from products of Si{sub 3}N{sub 4} etching. Rinsing in deionized water immediately after HF etching for at least 30 s avoids such deposition and yields a smooth surface without evidence of Si-H termination. Instead, fluorine and oxygen are found to terminate a sizeable fraction of the surface in the form of Si-F and possibly Si-OH bonds. The relatively unique fluorine termination is remarkably stable in both air and water and could lead to further chemical functionalization pathways.

Authors:
; ; ; ; ; ;  [1]; ;  [2]
  1. Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas 75080 (United States)
  2. Components Research, Intel Corporation, Hillsboro, Oregon 97124 (United States)
Publication Date:
OSTI Identifier:
22395605
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 26; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; AIR; CRYSTALS; DEPOSITION; ETCHING; FILMS; FLUORINE; HYDROFLUORIC ACID; MICROELECTRONICS; MORPHOLOGY; OXYGEN; SCANNING ELECTRON MICROSCOPY; SILICON NITRIDES; SURFACES; WATER; X-RAY PHOTOELECTRON SPECTROSCOPY

Citation Formats

Liu, Li-Hong, Debenedetti, William J. I., Peixoto, Tatiana, Gokalp, Sumeyra, Shafiq, Natis, Veyan, Jean-François, Chabal, Yves J., E-mail: chabal@utdallas.edu, Michalak, David J., and Hourani, Rami. Morphology and chemical termination of HF-etched Si{sub 3}N{sub 4} surfaces. United States: N. p., 2014. Web. doi:10.1063/1.4905282.
Liu, Li-Hong, Debenedetti, William J. I., Peixoto, Tatiana, Gokalp, Sumeyra, Shafiq, Natis, Veyan, Jean-François, Chabal, Yves J., E-mail: chabal@utdallas.edu, Michalak, David J., & Hourani, Rami. Morphology and chemical termination of HF-etched Si{sub 3}N{sub 4} surfaces. United States. doi:10.1063/1.4905282.
Liu, Li-Hong, Debenedetti, William J. I., Peixoto, Tatiana, Gokalp, Sumeyra, Shafiq, Natis, Veyan, Jean-François, Chabal, Yves J., E-mail: chabal@utdallas.edu, Michalak, David J., and Hourani, Rami. Mon . "Morphology and chemical termination of HF-etched Si{sub 3}N{sub 4} surfaces". United States. doi:10.1063/1.4905282.
@article{osti_22395605,
title = {Morphology and chemical termination of HF-etched Si{sub 3}N{sub 4} surfaces},
author = {Liu, Li-Hong and Debenedetti, William J. I. and Peixoto, Tatiana and Gokalp, Sumeyra and Shafiq, Natis and Veyan, Jean-François and Chabal, Yves J., E-mail: chabal@utdallas.edu and Michalak, David J. and Hourani, Rami},
abstractNote = {Several reports on the chemical termination of silicon nitride films after HF etching, an important process in the microelectronics industry, are inconsistent claiming N-H{sub x}, Si-H, or fluorine termination. An investigation combining infrared and x-ray photoelectron spectroscopies with atomic force and scanning electron microscopy imaging reveals that under some processing conditions, salt microcrystals are formed and stabilized on the surface, resulting from products of Si{sub 3}N{sub 4} etching. Rinsing in deionized water immediately after HF etching for at least 30 s avoids such deposition and yields a smooth surface without evidence of Si-H termination. Instead, fluorine and oxygen are found to terminate a sizeable fraction of the surface in the form of Si-F and possibly Si-OH bonds. The relatively unique fluorine termination is remarkably stable in both air and water and could lead to further chemical functionalization pathways.},
doi = {10.1063/1.4905282},
journal = {Applied Physics Letters},
number = 26,
volume = 105,
place = {United States},
year = {Mon Dec 29 00:00:00 EST 2014},
month = {Mon Dec 29 00:00:00 EST 2014}
}
  • We present a comparative scanning tunneling microscopy (STM) study on the porous layer formation in two different fluoride containing solution, HF/ethanol and concentrated NH{sub 4}F solution. After etching in dilute HF solution the samples display a high density of micropores with typical diameters ranging from 5 to 25 nm, while NH{sub 4}F treated surfaces display shallow macropores of several hundred nm in diameter. These structural differences are discussed by comparing the different activity of both solutions for chemical etching of Si in the adsence of an external potential, which provides an additional reaction channel also under anodic conditions. 21 refs.,more » 3 figs.« less
  • Highlights: • CVD method was successfully applied to obtain Si{sub 3}N{sub 4} microcoils in high yield without the presence of catalyst. • The process was systematically investigated through a series of control experiments. • The effects of synthesis parameters on the yield and morphology of Si{sub 3}N{sub 4} microcoils were found. • The growth mechanism of the Si{sub 3}N{sub 4} microcoils could be explained by the different growth rates between the amorphous layer and the crystalline layer. - Abstract: In this study, we provided a reliable chemical vapor deposition (CVD) method to synthesize high-purity Si{sub 3}N{sub 4} microcoils in highmore » yield without the presence of catalyst. The achieved products were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscope. The results indicated that the yield and morphology of Si{sub 3}N{sub 4} products were influenced by the synthesis parameters such as reaction temperature, reaction time and gas flow rate. The particular conditions favorable to high yield synthesis of Si{sub 3}N{sub 4} microcoils were obtained through a series of control experiments. Furthermore, the growth of Si{sub 3}N{sub 4} microcoils was supposed to be in accord with vapor-solid (VS) growth process and the different growth rates between the amorphous layer and the crystalline layer were used to explain the formation of the coil geometry.« less
  • Local cation order approaching ideal bulk termination was found for cleaned (001) surfaces of YBa{sub 2}Cu{sub 3}O{sub 7} crystals by ion-channeling surface-peak analysis. Surfaces etched in dilute CH{sub 3}OH:Br{sub 2} and ultrasonically agitated in CH{sub 3}OH to dislodge the Br{sub 2} appear terminated preferentially by the Cu-O double-plane'' sequence, containing less than 1/2-cation monolayer of surface disorder. Planar polishing with ion beams incident at a glancing angle on a rotating crystal leaves residual disorder as low as {similar to}8 A, damage which is readily removed by a light chemical etch.
  • Local cation order approaching ideal bulk termination was found for cleaned (001) surfaces of YBa{sub 2}Cu{sub 3}O{sub 7} crystals by ion-channeling surface-peak analysis. Surfaces etched in dilute CH{sub 3}OH:Br{sub 2} and ultrasonically agitated in CH{sub 3}OH to dislodge the Br{sub 2} appear terminated preferentially by the Cu-O double-plane'' sequence, containing less than 1/2-cation monolayer of surface disorder. Planar polishing with ion beams incident at a glancing angle on a rotating crystal leaves residual disorder as low as {similar to}8 A, damage which is readily removed by a light chemical etch.
  • The bulk chemical reactions between Si{sub 3}N{sub 4} and Ni have been investigated from a thermodynamics perspective by Klomp et al. and Heikinheimo et al., and from experiments by Suganuma et al., Schuster et al., Brito et al., Ishikawa et al., and Heikinheimo et al. The chemical interaction between Si{sub 3}N{sub 4} and Ni-based alloy was investigated by Benett et al., Mehan et al., and Peteves et al. In this work, instead of the Ni-Cr, or model Ni-based superalloy (Ni-Cr-Al alloy), the industrial superalloy, IN-738, was used. For comparing the different chemical behaviors between the pure Ni and Ni-based superalloymore » with Si{sub 3}N{sub 4}, solid state diffusion bonding of Ni/Si{sub 3}N{sub 4} and IN-738/Si{sub 3}N{sub 4} were bonded in the same bonding conditions, except Ni/Si{sub 3}N{sub 4} specimens whose bonding time were longer than that of IN-738/Si{sub 3}N{sub 4} specimen.« less