Arsenic Doping of Chemical Vapor Deposited Polycrystalline Silicon Using SiH4 ‐  H 2 ‐ AsH3 Gas System

Abstract

The arsenic concentration (CAs) in polycrystalline silicon (poly-Si) deposited under various deposition conditions in the deposition temperature range 670~176 using SiH4-H2-AsH3 gas system has been determined by neutron activation analysis. From the experimental results, it was found that CAs increases with decreasing deposition temperature and with increasing partial pressure of AsH3 in the gas introduced into the reactor (PAsH3Ci)), and that for lower PAsH3 (i) region, CAs decreases with decreasing gas velocity and with increasing deposition rate, and for higher PAsH3(i) region, CAs is independent of gas velocity and deposition rate. From the analyses of the experimental data, it was suggested that (i) for lower PAsHS(i) region, CAs is limited by the diffusion of As-containing species, such as As molecule, As2 molecule, and A~4 molecule, in the stagnant layer formed by gas stream, and for higher PAsH.~ (i~ region, gAs is controlled by the surface reaction; (ii) monatomic As existing at wafer surface is incorporated in poly-Si in accordance with Henry's law;(iii) the transfer coefficient of As atoms in gas phase increases slightly with increasing deposition temperature and gas velocity; (iv) the segregation coefficient of monatomic As between gas phase and poly-Si (m) is approximated by m = 1.5 • l0 s exp (--71.5 kcal/mole/RT); (v) the energy of As-Si bond is 44.5 kcal/mole. Arsenic-doped polycrystalline silicon (As-doped poly-Si) is an important material as a diffusion source for the emitters of microwave transistors (1, 2) and as a gate electrode of MOSLSI's (3). In the fabrication process of fine pattern silicon devices, the deposition temperature of As-doped poly-Si has been selected in the range between 650 ~ and 800~ taking account of grain size (4-6). The deposition rate, structure, and resistivity of As-doped poly-Si have been investigated by many workers (5-7), however, little has been known about As doping mechanism of chemical vapor deposited poly-Si at deposition temperature between 650 ~ and 800~ which is a basic knowledge for using As-doped poly-Si.In the present work, the As concentration (CAs) in poly-Si deposited under various deposition conditions in the deposition temperature range 670~176 using the SiH4-H2-AsH~ gas system was obtained by neutron activation analysis. From the experimental results, it was suggested that, for lower PAsH3 (i) region, CAs is limited by the diffusion of As-containing species in the stagnant layer (8) formed by gas stream, and for higher PAsHa(i) region, CAs is controlled by the surface reaction, and that monatomic As existed at wafer surKey words: CVD, doping, semiconductor, bonding.face is incorporated in poly-Si in accordance with Henry's law. The temperature dependences of the transfer coefficient of As atoms in H2 and the segregation coefficient of monatomic As between gas phase and poly-Si were also obtained, and the energy of As-Si bond was determined using Weiser's model (9). ExperimentalThe As-doped poly-Si was deposited in an rf heated reactor usi...

Si Doping of Vapor–Liquid–Solid GaAs Nanowires: n-Type or p-Type?

“…The main contribution to A is the difference of internal energies between, on one hand, a pure GaAs cell, and on the other hand the same GaAs cell but with a Si impurity replacing either As (system I) or Ga (system II) atom. These energies have been reported for surface segregation, 32,33 which is very unlike the conditions of our VLS system. Therefore, they were evaluated for this work by first-principles DFT.…”

High-Speed Rotating-Disk Chemical Vapor Deposition Process for In-Situ Arsenic-Doped Polycrystalline Silicon Films

“…The deposition rate logarithmically increased in the temperature range from 680 to 720 C. The activation energy E a of deposition rate was about 3.6 eV for the Asdoped poly-Si film, and is higher than that for the undoped poly-Si film. These results are almost the same as the data reported by Murota et al 17) Figure 3 shows the distributions of the deposition rate and wafer temperature along the wafer radius for the AsH 3 flow rates of 0 and 30 sccm. The film thickness was approximately 350 nm.…”

Diffusion of As, P, and B from Doped Polysilicon through Thin SiO2 Films into Si Substrates

“…Dsio2/Dsi = [d(dox/~/t)/d(%/~/t) ] 2 [13] To derive Ds,o2 from Eq. [13], the Dsi values for the low impurity concentration, denoted by superscript ,,o,,, were set as follows, by assuming them to be independent of the concentration (6)(7)(8) D~i_As (cm 2 s-') = 0.32 exp (-3.56 eV/kT) [14] D~i_ p (cm 2 s -1) = 3.85 exp (-3.66 eV/kT) [15] D~_ B (cm 2 s -1) = 484 exp (-4.3 eV/kT) [16] Ds,o2 can also be evaluated by fitting the C~ vs. do~/~/t dependence to an erfc curve in Eq. [12], and m can be derived from the absolute values of C~ using Eq.…”