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

Abstract

We have developed high-speed rotating-disk chemical vapor deposition (CVD) equipment for polycrystalline silicon (poly-Si) films. This CVD equipment has an enhanced ability to reduce the boundary layer thickness at a given temperature above a wafer surface, and to suppress vapor-phase reactions. We investigated in-situ arsenic-doped poly-Si film deposition using silane (SiH4), arsine (AsH3) and nitrogen (N2) in a high-speed rotating-disk CVD as functions of AsH3 flow rate and deposition temperature. Both the deposition rate and resistivity decreased with increasing AsH3 flow rate. A deposition rate of 120 nm/min, a resistivity of 16 mΩ·cm, a film thickness nonuniformity of ±5%, and a number of particles of less than 20 (over 200 nm in diameter) were achieved at a deposition temperature of 680°C for in-situ arsenic-doped poly-Si deposition on a 200-mm-diameter silicon (Si) wafer. Moreover, it was confirmed that the concentration of As in the poly-Si film was low at the initial stage of deposition, and that this process has a high gap filling capability in a hole of 0.18 µm width and 7 µm depth. It was also confirmed that there were conditions for a high step coverage of more than 1. These properties are inferred to be due to the adsorbed AsH3 preventing the adsorption of SiH4.

Improvement of m‐plane ZnO films formed on buffer layers on sapphire substrates by mist chemical vapor deposition

“…b, two peaks spaced by 180° were observed for both ZnO and sapphire, since the crystal lattices of m‐plane ZnO and m‐plane sapphire are both rectangular with two‐fold symmetry. The c ‐axes of ZnO and that of sapphire perpendicularly crossed each other on the sapphire substrate, namely ZnO [0001] || sapphire and ZnO || sapphire [0001]. In this φ scan measurement, the ZnO (10–11) and sapphire (11–20) planes were used as the monitoring planes, where Bragg conditions were set to be satisfied.…”

“…and , it was shown that the thickness and crystallographic properties were homogeneous across the substrate, and that the ZnO film was epitaxially grown on the sapphire substrate . In the direction lateral to the sapphire substrate, four small rectangular ZnO lattices are formed on one large sapphire rectangular lattice in the sapphire [0001] direction, indicating domain‐matching epitaxy , where the lattice mismatch in the ZnO [0001] direction is 9.7%, and that in the ZnO direction is 0.1%.…”

“…The boundary‐layer theory in fluid dynamics suggests that when a disk rotates at a high speed keeping laminar flow, uniform temperature and concentration of the gas are expected on the rotating disk surface . Already, this high‐speed rotation‐type systems have been used in CVD or MOCVD for Ge, Si, group III–V material such as AlGaInP . Recently, a couple of companies have applied this method to MOCVD systems for mass production of GaN‐based devices and realized high uniformity.…”

“…In addition, uniform ZnO single-crystal film was successfully formed over 2-inch wafers as described below. Figure 3a [11][12][13][14][15][16][17][18][19][20] and ZnO [11][12][13][14][15][16][17][18][19][20] || sapphire [0001]. In this w scan measurement, the ZnO (10-11) and sapphire (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) planes were used as the monitoring planes, where Bragg conditions were set to be satisfied.…”