• Title/Summary/Keyword: crystallization of a-Si film

Search Result 192, Processing Time 0.029 seconds

Fabrication of Polycrystalline Si Films by Silicide-Enhanced Rapid Thermal Annealing and Their Application to Thin Film Transistors (Silicide-Enhanced Rapid Thermal Annealing을 이용한 다결정 Si 박막의 제조 및 다결정 Si 박막 트랜지스터에의 응용)

  • Kim, Jone Soo;Moon, Sun Hong;Yang, Yong Ho;Kang, Sung Mo;Ahn, Byung Tae
    • Korean Journal of Materials Research
    • /
    • v.24 no.9
    • /
    • pp.443-450
    • /
    • 2014
  • Amorphous (a-Si) films were epitaxially crystallized on a very thin large-grained poly-Si seed layer by a silicide-enhanced rapid thermal annealing (SERTA) process. The poly-Si seed layer contained a small amount of nickel silicide which can enhance crystallization of the upper layer of the a-Si film at lower temperature. A 5-nm thick poly-Si seed layer was then prepared by the crystallization of an a-Si film using the vapor-induced crystallization process in a $NiCl_2$ environment. After removing surface oxide on the seed layer, a 45-nm thick a-Si film was deposited on the poly-Si seed layer by hot-wire chemical vapor deposition at $200^{\circ}C$. The epitaxial crystallization of the top a-Si layer was performed by the rapid thermal annealing (RTA) process at $730^{\circ}C$ for 5 min in Ar as an ambient atmosphere. Considering the needle-like grains as well as the crystallization temperature of the top layer as produced by the SERTA process, it was thought that the top a-Si layer was epitaxially crystallized with the help of $NiSi_2$ precipitates that originated from the poly-Si seed layer. The crystallinity of the SERTA processed poly-Si thin films was better than the other crystallization process, due to the high-temperature RTA process. The Ni concentration in the poly-Si film fabricated by the SERTA process was reduced to $1{\times}10^{18}cm^{-3}$. The maximum field-effect mobility and substrate swing of the p-channel poly-Si thin-film transistors (TFTs) using the poly-Si film prepared by the SERTA process were $85cm^2/V{\cdot}s$ and 1.23 V/decade at $V_{ds}=-3V$, respectively. The off current was little increased under reverse bias from $1.0{\times}10^{-11}$ A. Our results showed that the SERTA process is a promising technology for high quality poly-Si film, which enables the fabrication of high mobility TFTs. In addition, it is expected that poly-Si TFTs with low leakage current can be fabricated with more precise experiments.

Fabrication of polycrystalline Si films by rapid thermal annealing of amorphous Si film using a poly-Si seed layer grown by vapor-induced crystallization

  • Yang, Yong-Ho;An, Gyeong-Min;Gang, Seung-Mo;An, Byeong-Tae
    • Proceedings of the Materials Research Society of Korea Conference
    • /
    • 2010.05a
    • /
    • pp.58.1-58.1
    • /
    • 2010
  • We have developed a novel crystallization process, where the crystallization temperature is lowered compared to the conventional RTA process and the metal contamination is lowered compared to the conventional VIC process. A very-thin a-Si film was deposited and crystallized at $550^{\circ}C$ for 3 h by the VIC process and then a thick a-Si film was deposited and crystallized by the RTA process at $680^{\circ}C$ for 5 min using the VIC poly-Si layer as a crystallization seed layer. The RTA crystallized temperature could be lowered up to $50^{\circ}C$, compared to RTA process alone. The poly-Si film appeared a needle-like growth front and relatively well-arranged (111) orientation. In addition, the Ni concentration in the poly-Si film was lowered to $3{\times}10^{17}\;cm^{-3}$ and that at the poly-Si/$SiO_2$ interface was lowered to $5{\times}10^{19}\;cm^{-3}$. The reduction in metal contamination could be greatly helpful to achieve a low leakage current in poly-Si TFT, which is the critical parameter for commercialization of AMOLED.

  • PDF

Effective Annealing and Crystallization of Si film for Advanced TFT System

  • Noguchi, Takashi
    • 한국정보디스플레이학회:학술대회논문집
    • /
    • 2009.10a
    • /
    • pp.254-257
    • /
    • 2009
  • The crystallization and activated annealing effect of Si films using an excimer laser and a new CW blue laser are described comparing with furnace annealing (SPC) for the application of advanced TFTs and future applications. Currently, pulsed ELA is used extensively as a LTPS process on glass substrates as the efficiency is high in UV region for thin Si film of 40- 60 nm thickness. ELA enables extremely low resistivity for both n- and p-typed Si films. On the other hand, CW BLDA enables the smooth Si surface having arbitral grains from micro-grains to anisotropic huge grain structure only controlling its power density.

  • PDF

Crystallization of a-Si Induced by Ni-Si oxide source

  • Meng, Z.;Liu, Z.;Zhao, S.;Wu, C.;Wong, M.;Kwok, H.;Xiong, S.
    • 한국정보디스플레이학회:학술대회논문집
    • /
    • 2008.10a
    • /
    • pp.985-988
    • /
    • 2008
  • Metal induced crystallization of a-Si with a source of Ni/Si oxide was studied. Its mechanism to induce crystallization was discussed. It was found that new source behaves an effect of self-released nickel and reducing nickel residua, so can provide a wider process tolerance; improve the uniformity and stability of TFTs.

  • PDF

A Strategy on the Growth of Large Area Polycrystalline Si Virtual Substrate Using Al-Induced Crystallization (알루미늄 유도 결정화를 이용한 대면적 다결정 Si 가상 기판 성장 전략)

  • Dohyun Kim;Kwangwook Park
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.37 no.1
    • /
    • pp.26-35
    • /
    • 2024
  • Aluminum-induced crystallization (AIC) as a route to reduce the fabrication cost and to obtain polycrystalline Si (p-Si) thin-film of large grain size is a promising alternative of single-crystalline (s-Si) substrate or p-Si thin-film obtained by conventional methods such as solid phase crystallization (SPC) and laser-induced crystallization (LIC). As the AIC process occurs at the interface between a-Si and Al thin-films, there are various process and interface parameters. Also, it directly means that there is a certain parametric window to obtain p-Si of large grain size having uniform crystal orientation. In this article, we investigate the effect of the various process and interface parameters to obtain p-Si of large grain size and uniform crystal orientation from the literature review. We also suggest the potential use of the p-Si as a virtual substrate for the growth of various compound semiconductors in a form of low-dimension as well as thin-film as a way for their monolithic integration on Si.

Fabrication and Characteristics of poly-Si thin film transistors by double-metal induced lteral crystallization at 40$0^{\circ}C$ (이중 금속 측면 결정화를 이용한 40$0^{\circ}C$ 다결정 실리콘 박막 트랜지서터 제작 및 그 특성에 관한 연구)

  • 이병일;정원철;김광호;안평수;신진욱;조승기
    • Journal of the Korean Institute of Telematics and Electronics D
    • /
    • v.34D no.4
    • /
    • pp.33-39
    • /
    • 1997
  • The crystallization temperature of an amorphous silicon (a-Si) can be lowered down to 400.deg. C by a new method : Double-metal induced lateral crystallization (DMILC). The a-Si film was laterally crystallized from Ni and Pd deposited area, and its lateral crystallization rate reaches up to 0.2.mu.m/hour at that temperature and depends on the overlap length of Ni and Pd films; the shorter the overlap length, the faster the rate. Poly-Silicon thin film transistors (poly-Si TFT's) fabricated by DMILC at 400.deg. C show a field effect mobility of 38.5cm$^{3}$/Vs, a minimum leakage current of 1pA/.mu.m, and a slope of 1.4V/dec. The overlap length does not affect the characteristics of the poly-Si TFT's, but determines the lateral crystallization rate.

  • PDF

Evaluation of Solar Cell Properties of Poly-Si Thin Film Fabricated with Novel Process Conditions for Solid Phase Crystallization (고상 결정화법을 위한 새로운 공정조건으로 제작된 다결정 Si 박막의 태양전지 특성 평가)

  • Kweon, Soon-Yong;Jeong, Ji-Hyun;Tao, Yuguo;Varlamov, Sergey
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.24 no.9
    • /
    • pp.766-772
    • /
    • 2011
  • Amorphous Si (a-Si) thin films of $p^+/p^-/n^+$ were deposited on $Si_3N_4$/glass substrate by using a plasma enhanced chemical vapor deposition (PECVD) method. These films were annealed at various temperatures and for various times by using a rapid thermal process (RTP) equipment. This step was added before the main thermal treatment to make the nuclei in the a-Si thin film for reducing the process time of the crystallization. The main heat treatment for the crystallization was performed at the same condition of $600^{\circ}C$/18 h in conventional furnace. The open-circuit voltages ($V_{oc}$) were remained about 450 mV up to the nucleation condition of 16min in the nucleation RTP temperature of $680^{\circ}C$. It meat that the process time for the crystallization step could be reduced by adding the nucleation step without decreasing the electrical property of the thin film Si for the solar cell application.

Characteristics of poly-Si TFTs using Excimer Laser Annealing Crystallization and high-k Gate Dielectrics (Excimer Laser Annealing 결정화 방법 및 고유전 게이트 절연막을 사용한 poly-Si TFT의 특성)

  • Lee, Woo-Hyun;Cho, Won-Ju
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.21 no.1
    • /
    • pp.1-4
    • /
    • 2008
  • The electrical characteristics of polycrystalline silicon (poly-Si) thin film transistor (TFT) crystallized by excimer laser annealing (ELA) method were evaluated, The polycrystalline silicon thin-film transistor (poly-Si TFT) has higher electric field-effect-mobility and larger drivability than the amorphous silicon TFT. However, to poly-Si TFT's using conventional processes, the temperature must be very high. For this reason, an amorphous silicon film on a buried oxide was crystallized by annealing with a KrF excimer laser (248 nm)to fabricate a poly-Si film at low temperature. Then, High permittivity $HfO_2$ of 20 nm as the gate-insulator was deposited by atomic layer deposition (ALD) to low temperature process. In addition, the solid phase crystallization (SPC) was compared to the ELA method as a crystallization technique of amorphous-silicon film. As a result, the crystallinity and surface roughness of poly-Si crystallized by ELA method was superior to the SPC method. Also, we obtained excellent device characteristics from the Poly-Si TFT fabricated by the ELA crystallization method.

Crystallization of Amorphous Silicon Films by Field-Aided Lateral Crystallization (FALC) technique at $350^{\circ}C$

  • Park, Kyoung-Wan;Cho, Ki-Taek;Choi, Duck-Kyun
    • 한국정보디스플레이학회:학술대회논문집
    • /
    • 2002.08a
    • /
    • pp.548-551
    • /
    • 2002
  • The crystallization of amorphous silicon (a-Si) was achieved using a field aided lateral crystallization (FALC) process at 350 $^{\circ}C$. Under the influence of an electric field, Cu is found to drastically enhance the lateral crystallization velocity of a-Si. When an electric field was applied to the selectively Cu-deposited a-Si film during the heat treatment at temperature as low as 350 $^{\circ}C$, dendrite-shaped crystallization of a-Si progressed toward Cu-free region and the crystallization from negative electrode side toward positive electrode side was accelerated. We identified that 1000${\AA}$ thick a-Si film was completely crystallized by Cu-FALC process at 350 $^{\circ}C$ by TEM analysis.

  • PDF

A New process for the Solid phase Crystallization of a-Si by the thin film heaters (박막히터를 사용한 비정질 실리콘의 고상결정화)

  • 김병동;정인영;송남규;주승기
    • Journal of the Korean Vacuum Society
    • /
    • v.12 no.3
    • /
    • pp.168-173
    • /
    • 2003
  • Recently, according to the rapid progress in Flat-panel-display industry, there has been a growing interest in the poly-Si process. Compared with a-Si, poly-Si offers significantly high carrier mobility, so it has many advantages to high response rate in Thin Film Transistors (TFT's). We have investigated a new process for the high temperature Solid Phase Crystallization (SPC) of a-Si films without any damages on glass substrates using thin film heater. because the thin film heater annealing method is a very rapid thermal process, it has very low thermal budget compared to the conventional furnace annealing. therefore it has some characteristics such as selective area crystallization, high temperature annealing using glass substrates. A 500 $\AA$-thick a-Si film was crystallized by the heat transferred from the resistively heated thin film heaters through $SiO_2$ intermediate layer. a 1000 $\AA$-thick $TiSi_2$ thin film confined to have 15 $\textrm{mm}^{-1}$ length and various line width from 200 to 400 $\mu\textrm{m}$ was used as the thin film heater. By this method, we successfully crystallized 500 $\AA$-thick a-Si thin films at a high temperature estimated above $850^{\circ}C$ in a few seconds without any thermal deformation of g1ass substrates. These surprising results were due to the very small thermal budget of the thin film heaters and rapid thermal behavior such as fast heating and cooling. Moreover, we investigated the time dependency of the SPC of a-Si films by observing the crystallization phenomena at every 20 seconds during annealing process. We suggests the individual managements of nucleation and grain growth steps of poly-Si in SPC of a-Si with the precise control of annealing temperature. In conclusion, we show the SPC of a-Si by the thin film heaters and many advantages of the thin film heater annealing over other processes