Bulletin of the American Physical Society
2005 58th Gaseous Electronics Conference
Sunday–Thursday, October 16–20, 2005; San Jose, California
Session UH1: Etching Mechanisms |
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Chair: Eric Hudson, LAM Research Room: Doubletree Hotel Pine |
Thursday, October 20, 2005 8:00AM - 8:15AM |
UH1.00001: Profile simulation of high-aspect-ratio contact etching including charging effect Seokhyun Lim, Yongjin Kim, Yero Lee, Taikyung Kim, Gyung-Jin Min, Chang-Jin Kang, HanKu Cho, Joo-Tae Moon As the design rule of semiconductor devices shrinks, high- aspect-ratio contact (HARC) etching of dielectrics becomes one of the most critical processes. Etch loading, bowing and pattern deformation at the bottom are serious problems in the HARC etching process, while the mechanism of the phenomena has not been fully understood yet. HARC etching requires high ion energy flux, resulting in severe charge build-up on the surface, which is an important factor that should be considered to understand the mechanism. In the present work, we perform particle simulation of ion and electron under the electric field generated by the charges accumulated on the dielectric surface and investigate the effects of various parameters of ion energy, ion angle, electron energy and pattern geometry on the charge build- up and ion energy flux distribution along the dielectric surface in detail. The charging effect on the profile evolution and the mechanism of various phenomena during the HARC etching process is also investigated. [Preview Abstract] |
Thursday, October 20, 2005 8:15AM - 8:30AM |
UH1.00002: A self-consistent modeling of feature profile evolution under competition between etching and deposition Takashi Shimada, Takashi Yagisawa, Toshiaki Makabe Radical deposition is one of the important issues for SiO$_2$ etching as the radicals contribute to the protection of side wall as well as the acceleration of etching by the formation of a mixing layer on the bottom. We investigate the relationship among local wall charging, etching and deposition in a SiO$_2$ trench etching, by considering the transport of electrons, positive ions, and neutral radicals in the two-dimensional sheath structure in a two frequency-capacitively coupled plasma in CF$_4$/Ar. Emphasis is given on the influence of both charging and neutral radical accumulation inside the SiO$_2$ trench during plasma etching. Feature profiles of the SiO$_2$ trench are estimated by the Level Set method under conditions with/without charging and neutral deposition. In particular, the effect of the bias amplitude on the profile evolution is discussed under the competition between etching and deposition. [Preview Abstract] |
Thursday, October 20, 2005 8:30AM - 8:45AM |
UH1.00003: Development of Nano-Contact Etch Process Using New Gas Chemistry. Jong-Woo Sun, Chul-Ho Shin, Gyung-Jin Min, Chang-Jin Kang, HanKu Cho, Joo-Tae Moon As device feature size shrinks to sub-0.1$\mu$m, oxide contact etching has become difficult to satisfy the process requirements. Especially, the aspect ratio of device has become higher and the mask thickness thinner. These trends require the ability to etch with high selectivity against mask and better profile control. In this paper, development of oxide contact etch process using new gas chemistry(CxFyHz) is investigated. It has already been proposed that the reactive gas mixture contain polymer and etchant gases. However, with current gas species, we have some limitations to meet process specification for next generation device. Compared to other common polymer former gases, it is found that our new additive gas has significant effect to increase selectivity against mask and to control feature profile. From the experiments, the selectivity of oxide over mask is enhanced up to 30{\%} and it provides some potential possibility for profile control compared to other gases. These effects have also been analyzed by QMS (Quadrupole Mass Spectrometer). [Preview Abstract] |
Thursday, October 20, 2005 8:45AM - 9:00AM |
UH1.00004: Etching of high-$k$ and metal gate materials in high-density chlorine-containing plasmas Kouichi Ono, Keisuke Nakamura, Kazushi Osari, Tomohiko Kitagawa, Kazuo Takahashi Plasma etching of high dielectric constant ($k)$ films and metal electrodes is indispensable for the fabrication of high-$k$ gate stacks. This paper presents the etching characteristics of high-$k$ materials of HfO$_{2}$ and metals of Pt and TaN using high-density chlorine-containing plasmas, along with the plasma and surface diagnostics concerned. Attention was focused on etch chemistries and plasma conditions to achieve a high etch selectivity of $>>$1 for HfO$_{2}$ over the underlying Si and SiO$_{2}$; regarding Pt and TaN, the emphasis was placed on the etch anisotropy and selectivity of metal electrodes over the underlying HfO$_{2}$ and overlying SiO$_{2} $. The etching of HfO$_{2}$ was performed in BCl$_{3}$ without rf biasing, giving an etch rate of about 5 nm/min with a high selectivity of $>$10 over Si and SiO$_{2}$. At lower pressures, the deposition of BCl$_{x}$ was found to occur on all the surfaces of interest; however, on HfO$_{2}$ surfaces, the deposition followed the etching during a few tens of seconds. The etching of Pt and TaN was performed with high and low rf biasing, respectively, giving a Pt etch rate of about several tens nm/min and a TaN etch rate of about 200 nm/min, with a high selectivity of $>$8 over HfO$_{2}$ and SiO$_ {2}$ in Ar/O$_{2}$ for Pt and in Ar/Cl$_{2}$ for TaN. The etched profiles were outwardly tapered for Pt, while the TaN profiles were found to be almost anisotropic. [Preview Abstract] |
Thursday, October 20, 2005 9:00AM - 9:15AM |
UH1.00005: SiO$_{2}$ and Si$_{3}$N$_{4}$ Etch Mechanisms in NF$_{3}$/C$_{2}$H$_{4}$ Plasma Puthajat Machima, Noah Hershkowitz Low-pressure inductive plasma was used to study SiO$_{2}$ and Si$_{3}$N$_{4}$ etching with the NF$_{3}$/C$_{2}$H$_{4}$ chemistry. NF$_{3}$ and C$_{2}$H$_{4}$ were used so that fluorine and carbon could be supplied from feed gases other than global warming fluorocarbons. Etch rates of SiO$_{2}$ over a wide range of conditions are less than 0.8 times the Si$_{3}$N$_{4}$ etch rates. Ex-situ XPS was used to determine the characteristics of a very thin steady-state film, to establish etch mechanisms. XPS results show that CH$_{x}$F, CF$_{2}$, and CF$_ {3}$ were produced but in small concentrations compared to CH$_{x}$ and CN. Mass spectrometry and optical emission gave consistent results. C1s spectra from etched oxide samples show a large percentage of H$_{x}$C-CH$_{x} $ structures. Si$_{3}$N$_{4}$ appears to react easily with H$_{x} $C-CH$_{x}$ structures, yielding CN-bearing products and SiC. Etch rate and selectivity results of NF$_{3}$-based discharges fed with C$_{2}$H$_{2}$, C$_{4}$H$_{10}$, and CH$_{3}$F are similar to the NF$_{3}$/C$_ {2}$H$_{4}$ plasma. Comparisons of normalized F1s spectra of nitride and oxide etched under the same conditions show that relative concentrations of CF$_{2}$ and CF$_{3}$ on SiO$_{2}$ are much lower than the concentrations on Si$_{3}$N$_{4}$. It appears that SiO$_{2}$ preferentially reacts with only CF$_{2}$ and CF$_{3}$ but not with H$_{x}$C-CH$_{x}$ or CH$_{x} $F. Differences in the abilities of SiO$_{2}$ and Si$_{3}$N$_{4}$ to react with H$_{x}$C-CH$_{x}$ contributed to higher etch rates of Si$_{3} $N$_{4}$. Effects of bias frequency are presented. [Preview Abstract] |
Thursday, October 20, 2005 9:15AM - 9:30AM |
UH1.00006: Performance Tunable High-Frequency Inductively Coupled Plasma Technology in Application to Polysilicon Etcher and High Density Plasma CVD Jong W. Shon, GiChung Kwon, Hong Y. Chang High frequency ICP plasma technology is uniquely suited for 45nm technology node and below for its ability to produce plasma with low electron temperature and controllable ion energy. In this presentation we will discuss principles of this technology and its application to Poly etcher and HDP CVD. The low impedance resonance antenna can accomplish impedance matching in 13.56 MHz or 27.12 MHz source frequency. High density plasma is generated by the high current coils. Also, plasma uniformity can be controlled by the current in each antenna turns. The low capacitive voltage applied to antenna can minimize capacitive damage and reduce particles from ceramic plate. High frequency ICP source can generate plasma with low electron temperature compared to lower frequency ICP sources using 400 KHz or 2 MHz), which can minimize plasma damage on the wafer. The plasma density from this source is 1 $\times $10$^{11} \quad \sim $ 1 $\times $10$^{12}$ cm$^{-3 }$and the electron temperature is less than 2.5 eV in 27.12 MHz and 4 eV in 13.56 MHz. We obtained the plasma uniformity less than 5{\%}. For the applications, patterned WSi gate, poly-Si gate, and W-Bit line wafers were etched using a parallel resonance antenna. STI (Shallow Trench Isolation), ILD (Inter Layer Dielectric), and IMD (Inter Metal Dielectric) wafers were processed in a dome-typed antenna source for HDP CVD. The process characteristics of HDP CVD has proven in 0.13 micrometer technology with AR (aspect ratio) 5:1 and expected to provide next generation gap fill solution. The process characteristics of dry etcher have obtained minimal micro-loading effect less than +-5{\%}, high selectivity W to Hard Mask (SiN) more than 1.5:1, wide range CD bias control within 20 nm, and vertical profile more than 89 degree. [Preview Abstract] |
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