skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Correlation of film density and wet etch rate in hydrofluoric acid of plasma enhanced atomic layer deposited silicon nitride

Abstract

The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposition (ALD) of silicon nitride (SiN{sub x}), particularly for use a low k dielectric spacer. One of the key material properties needed for SiN{sub x} films is a low wet etch rate (WER) in hydrofluoric (HF) acid. In this work, we report on the evaluation of multiple precursors for plasma enhanced atomic layer deposition (PEALD) of SiN{sub x} and evaluate the film’s WER in 100:1 dilutions of HF in H{sub 2}O. The remote plasma capability available in PEALD, enabled controlling the density of the SiN{sub x} film. Namely, prolonged plasma exposure made films denser which corresponded to lower WER in a systematic fashion. We determined that there is a strong correlation between WER and the density of the film that extends across multiple precursors, PEALD reactors, and a variety of process conditions. Limiting all steps in the deposition to a maximum temperature of 350 °C, it was shown to be possible to achieve a WER in PEALD SiN{sub x} of 6.1 Å/min, which is similar to WER of SiN{sub x} from LPCVD reactions at 850 °C.

Authors:
; ; ; ;  [1];  [2];  [1];  [3]
  1. Department of Mechanical Engineering, Stanford University, Stanford, California 94305 (United States)
  2. Manufacturing Technology Center, Samsung Electronics, Suwon, Gyeonggi-Do (Korea, Republic of)
  3. (United States)
Publication Date:
OSTI Identifier:
22611521
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Advances; Journal Volume: 6; Journal Issue: 6; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CHEMICAL VAPOR DEPOSITION; CORRELATIONS; DENSITY; DIELECTRIC MATERIALS; DILUTION; EVALUATION; FILMS; HYDROFLUORIC ACID; LAYERS; PLASMA; SILICON NITRIDES; SPACERS; TRANSISTORS

Citation Formats

Provine, J., E-mail: jprovine@stanford.edu, Schindler, Peter, Kim, Yongmin, Walch, Steve P., Kim, Hyo Jin, Kim, Ki-Hyun, Prinz, Fritz B., and Department of Materials Science and Engineering, Stanford University, Stanford, California 94305. Correlation of film density and wet etch rate in hydrofluoric acid of plasma enhanced atomic layer deposited silicon nitride. United States: N. p., 2016. Web. doi:10.1063/1.4954238.
Provine, J., E-mail: jprovine@stanford.edu, Schindler, Peter, Kim, Yongmin, Walch, Steve P., Kim, Hyo Jin, Kim, Ki-Hyun, Prinz, Fritz B., & Department of Materials Science and Engineering, Stanford University, Stanford, California 94305. Correlation of film density and wet etch rate in hydrofluoric acid of plasma enhanced atomic layer deposited silicon nitride. United States. doi:10.1063/1.4954238.
Provine, J., E-mail: jprovine@stanford.edu, Schindler, Peter, Kim, Yongmin, Walch, Steve P., Kim, Hyo Jin, Kim, Ki-Hyun, Prinz, Fritz B., and Department of Materials Science and Engineering, Stanford University, Stanford, California 94305. 2016. "Correlation of film density and wet etch rate in hydrofluoric acid of plasma enhanced atomic layer deposited silicon nitride". United States. doi:10.1063/1.4954238.
@article{osti_22611521,
title = {Correlation of film density and wet etch rate in hydrofluoric acid of plasma enhanced atomic layer deposited silicon nitride},
author = {Provine, J., E-mail: jprovine@stanford.edu and Schindler, Peter and Kim, Yongmin and Walch, Steve P. and Kim, Hyo Jin and Kim, Ki-Hyun and Prinz, Fritz B. and Department of Materials Science and Engineering, Stanford University, Stanford, California 94305},
abstractNote = {The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposition (ALD) of silicon nitride (SiN{sub x}), particularly for use a low k dielectric spacer. One of the key material properties needed for SiN{sub x} films is a low wet etch rate (WER) in hydrofluoric (HF) acid. In this work, we report on the evaluation of multiple precursors for plasma enhanced atomic layer deposition (PEALD) of SiN{sub x} and evaluate the film’s WER in 100:1 dilutions of HF in H{sub 2}O. The remote plasma capability available in PEALD, enabled controlling the density of the SiN{sub x} film. Namely, prolonged plasma exposure made films denser which corresponded to lower WER in a systematic fashion. We determined that there is a strong correlation between WER and the density of the film that extends across multiple precursors, PEALD reactors, and a variety of process conditions. Limiting all steps in the deposition to a maximum temperature of 350 °C, it was shown to be possible to achieve a WER in PEALD SiN{sub x} of 6.1 Å/min, which is similar to WER of SiN{sub x} from LPCVD reactions at 850 °C.},
doi = {10.1063/1.4954238},
journal = {AIP Advances},
number = 6,
volume = 6,
place = {United States},
year = 2016,
month = 6
}
  • The plasma etch characteristics of aluminum nitride (AlN) deposited by low-temperature, 200 deg. C, plasma enhanced atomic layer deposition (PEALD) was investigated for reactive ion etch (RIE) and inductively coupled plasma-reactive ion etch (ICP-RIE) systems using various mixtures of SF{sub 6} and O{sub 2} under different etch conditions. During RIE, the film exhibits good mask properties with etch rates below 10r nm/min. For ICP-RIE processes, the film exhibits exceptionally low etch rates in the subnanometer region with lower platen power. The AlN film's removal occurred through physical mechanisms; consequently, rf power and chamber pressure were the most significant parameters inmore » PEALD AlN film removal because the film was inert to the SF{sub x}{sup +} and O{sup +} chemistries. The etch experiments showed the film to be a resilient masking material. This makes it an attractive candidate for use as an etch mask in demanding SF{sub 6} based plasma etch applications, such as through-wafer etching, or when oxide films are not suitable.« less
  • This work investigates the deposition of hydrogenated amorphous silicon nitride films using various low-temperature plasmas. Utilizing radio-frequency (RF, 13.56 MHz) and ultra-high frequency (UHF, 320 MHz) powers, different plasma enhanced chemical vapor deposition processes are conducted in the mixture of reactive N{sub 2}/NH{sub 3}/SiH{sub 4} gases. The processes are extensively characterized using different plasma diagnostic tools to study their plasma and radical generation capabilities. A typical transition of the electron energy distribution function from single- to bi-Maxwellian type is achieved by combining RF and ultra-high powers. Data analysis revealed that the RF/UHF dual frequency power enhances the plasma surface heating andmore » produces hot electron population with relatively low electron temperature and high plasma density. Using various film analysis methods, we have investigated the role of plasma parameters on the compositional, structural, and optical properties of the deposited films to optimize the process conditions. The presented results show that the dual frequency power is effective for enhancing dissociation and ionization of neutrals, which in turn helps in enabling high deposition rate and improving film properties.« less
  • Tantalum nitride thin films were deposited at 400 deg. C by plasma enhanced atomic layer deposition using an amido-based metal organic tantalum precursor. An Ar/N{sub 2}/H{sub 2} mixture was flowed upstream of a remote plasma system to produce the reactive species used for the nitridation process. The as-deposited film was amorphous and contained 15 at. % oxygen in the bulk of the film. High resolution photoelectron spectroscopy studies of the Ta 4f feature were consistent with the presence of the semiconducting Ta{sub 3}N{sub 5} phase in the as-deposited films. Electron diffraction studies were carried out by annealing the Ta{sub 3}N{submore » 5} film in situ in a transmission electron microscope. The high resistivity Ta{sub 3}N{sub 5} phase crystallized into the cubic TaN phase at 850 deg. C. This transformation appeared to coincide with outdiffusion of excess nitrogen from the Ta{sub 3}N{sub 5} film during the anneal. The resistivity of the crystallized film was estimated to be 600 {mu}{omega} cm from four point probe measurements.« less
  • Al{sub 2}O{sub 3} films, HfO{sub 2} films, and HfO{sub 2}/Al{sub 2}O{sub 3} stacked structures were deposited on n-type, Ga-face, GaN wafers using plasma-enhanced atomic layer deposition (PEALD). The wafers were first treated with a wet-chemical clean to remove organics and an in-situ combined H{sub 2}/N{sub 2} plasma at 650 Degree-Sign C to remove residual carbon contamination, resulting in a clean, oxygen-terminated surface. This cleaning process produced slightly upward band bending of 0.1 eV. Additional 650 Degree-Sign C annealing after plasma cleaning increased the upward band bending by 0.2 eV. After the initial clean, high-k oxide films were deposited using oxygenmore » PEALD at 140 Degree-Sign C. The valence band and conduction band offsets (VBOs and CBOs) of the Al{sub 2}O{sub 3}/GaN and HfO{sub 2}/GaN structures were deduced from in-situ x-ray and ultraviolet photoemission spectroscopy (XPS and UPS). The valence band offsets were determined to be 1.8 and 1.4 eV, while the deduced conduction band offsets were 1.3 and 1.0 eV, respectively. These values are compared with the theoretical calculations based on the electron affinity model and charge neutrality level model. Moreover, subsequent annealing had little effect on these offsets; however, the GaN band bending did change depending on the annealing and processing. An Al{sub 2}O{sub 3} layer was investigated as an interfacial passivation layer (IPL), which, as results suggest, may lead to improved stability, performance, and reliability of HfO{sub 2}/IPL/GaN structures. The VBOs were {approx}0.1 and 1.3 eV, while the deduced CBOs were 0.6 and 1.1 eV for HfO{sub 2} with respect to Al{sub 2}O{sub 3} and GaN, respectively.« less