Structure and crystal growth of atmospheric and low-pressure chemical-vapor-deposited silicon films

Abstract

Structure and crystal growth of undoped, as-deposited, and annealed silicon films prepared by chemical vapor deposition (CVD) and low-pressure chemical vapor deposition (LPCVD) of silane have been studied with use of x-ray diffraction, Raman spectroscopy, and scanning electron microscopy (SEM). The grain size and a complete texture analysis are performed on CVD films grown at atmospheric pressure and temperature range 600≤Td≤805 °C, LPCVD films grown in the pressure range 0.1≤Pd≤2 Torr and temperature range 500≤Td≤650 °C and annealed amorphous CVD and LPCVD films near Ta=600 °C. We obtain systematically amorphous, strong 〈220〉 polycrystalline, and inhomogeneous partially crystallized films 〈111〉 or 〈311〉 oriented depending on the deposition conditions. The presence of a given texture is explained by a model which takes into account the specific free surface energies of the starting equilibrium forms and the extinction of some crystalline planes by {111} slow growing facets. The appearance of the 〈220〉 texture is explained by a gas phase nucleation of crystal occurring during deposition, whereas the observed 〈311〉 texture of LPCVD films is supposed to be due to a gas-phase nucleation mechanism occurring during the first stages of deposition followed by a solid-phase crystallization mechanism.

Characterization of structure and role of different textures in polycrystalline Si films

“…Therefore, the change in q with increasing [SiF 4 ] may be controlled by the occurrence of h1 1 0i textured grains, though the mechanisms for this are unknown. Changes in strain in a crystalline Si film may also be considered for the control of dominant textures [25,26]. Bisaro et al [26] proposed that h3 1 1i planes are favorably formed as the films were strained.…”

“…Changes in strain in a crystalline Si film may also be considered for the control of dominant textures [25,26]. Bisaro et al [26] proposed that h3 1 1i planes are favorably formed as the films were strained. In the presented work, we observed almost the same tensile stress for the films prepared with [SiF 4 ] = 0 sccm.…”

Optimization of poly-silicon deposition process for switch

“…The polysilicon films deposited below 580℃ are amorphous whereas those deposited above 600℃ are crystalline in nature. Kamins has observed a similar transition at 600℃ and has suggested that the deposition at this temperature should be avoided in order to obtain reproducible structure [5][6][7][8].For obtaining uniform poly-silicon grains, experiments were made on poly-silicon deposition, doping, annealing. Considering that ion implantation and annealing tend to make poly-silicon grain growing rapidly and it is not easy to control the grain size of the poly-silicon, liquid source was adopted for diffusion doping, which could obtain high concentration and also avoid subsequent annealing process.…”

Influences of deposition and crystallization kinetics on the properties of silicon films deposited by low-pressure chemical vapour deposition from silane and disilane

“…Starting from amorphous silicon (a-Si) films obtained in the [2][3][4][5] Vd/Vc range (see below), the Vd/Vc decrease leads to the deposition of randomly semi-crystallized silicon (s-Si) due to the polysilicon grains growth during the silicon deposition process. As already shown in figure 8, this volume random crystallization is responsible for tensile stress and therefore for a residual stress increase.…”

“…The investigations have mainly concerned the silane SiH4 gaseous source [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. They evidenced that the deposition temperature T, the SiH4 partial pressure P and/or the deposition rate Vd were the main parameters for understanding the silicon films properties: cristallinity, microstructure, roughness, residual stress,… In parallel, the disilane Si2H6 gaseous source was also studied [18][19][20][21].…”