Growth of Polycrystalline Silicon Films at Low Temperature by Remote Plasma CVD
- PDF / 290,944 Bytes
- 6 Pages / 420.48 x 639 pts Page_size
- 62 Downloads / 293 Views
GROWTH OF POLYCRYSTALLINE SILICON FILMS AT LOW TEMPERATURE BY REMOTE PLASMA CVD
SUNG CHUL KIM, KYU CHANG PARK, SUNG KI KIM, JUNG MOK JUN AND JIN JANG Department of Physics, Kyung Hee University, Dongdaemoon-ku, Seoul 130-701, Korea
ABSTRACT We studied the growth of polycrystalline silicon by using remote plasma chemical vapour deposition technique. The effects of RF power and the substrate temperature on the structural properties have been investigated. With increasing the RF power, the crystalline volume fraction and the grain size increase up to 100W, but decrease for the further increase in power level. We obtained the poly-Si with the crystalline volume fraction of about 74 at. % at the substrate temperature of 3301C. INTRODUCTION The ideal device for the active matrix liquid crystal display(AM-LCD) is a single crystalline silicon thin film transistor(TFT) on glass substrate(for example, Corning 7059). This ideal device can be used as a switching element as well as a basic device for the driver circuits. But the present stage of technology is not so advanced. The hydrogenated amorphous silicon(a-Si:H) thin film transistor is the most suitable switching element for the direct view AM-LCDs, but the electron mobility is not high enough to make high aperture ratio TFT-LCD, which is particularly useful in LCD projector. The polycrystalline silicon(Poly-Si) TFT is better than a-Si:H for use as switching element as well as driver circuits because of the higher mobility. We can classify the poly-Si into three catagories depending on their process temperatures; high temperature, low temperature, and extremely low temperature Poly-Si. The high temperature process uses the thermal SiO2 as a gate insulator, and the low temperature poly-Si means the process temperature is around 6001C. The extremely low temperature indicates the process temperature is less than 4001C, which is called as-deposited low temperature Poly-Si. Recently, Oki[l-3] group reported poly-Si made at low temperature below 4001C by using a plasma chemical vapour deposition of the mixtures of silane, silicon tetrafluoride and hydrogen. In the present work, we have studied the growth of poly-Si by a remote plasma CVD technique using a mixture of silane and He. EXPERIMENTAL METHODS We used a remote plasma CVD system to make poly-Si. The He gas is introduced from the upstream side into the quartz tube, on which the rf coil is wrapped. Some of the He atoms are excited into metastable states by the rf power. The silane diluted in He is introduced from the circular ring in the reactor which is attached below the discharging tube[4-51. The deposition conditions are described in Table I. X-ray diffraction peaks are measured using Rikaku D/Max-3C X-ray diffractometer using CuKa line(A = 1.542k). Hitachi U-3410 UV/VIS spectrophotometer was used for UV reflectance measurement. It was measured in a wavelength region between 200 and 400 nm. Infra-Red(IR) transmittance was measured by Nicolet 730 Fourier Transform IR spectrophotometer to obtain Si-Hn(n= 1-3) bonding c
Data Loading...
