Coaxial Line-type Microwave Plasma Research Articles

Effect of Ar+ Ion Bombardment During Hydrogenated Amorphous Silicon Film Growth in Plasma Chemical Vapor Deposition System

We have developed the double tubed coaxial line type microwave plasma chemical vapor deposition (MPCVD) system to fabricate hydrogenated amorphous silicon (a-Si:H) films. We have studied the influence of Ar+ ion bombardment during a-Si:H film growth and clarified that the ion bombardment causes film surface heating effect and ion implanting effect. It is not sufficient to discuss only whether films are of good quality or not, when the ion bombardment energy is increased. In this study, we show that the effect of ion bombardment can be separated into the film surface heating effect and the ion implanting effect and discuss the influence of each effect on the film properties. We also show that the film surface temperature can be expressed as a function of the sheath voltage. It is clarified that a film with low dangling bond density can be fabricated at low temperatures if there is no ion bombardment.

二重管式同軸線路形マイクロ波プラズマCVDにおけるN<sub>2</sub>/SiH<sub>4</sub>プラズマのパラメータの空間分布

We have confirmed the new method of probe measurement in N2/SiH4 plasma. Using this method, we have measured the spatial distribution of plasma parameters such as electron temperature Te, electron density ne, plasma space potential Vs, floating potential Vf and sheath voltage Vs-Vf with varying the gas flow rate of SiH4 in the chamber of the double tubed coaxial line type microwave plasma CVD (MPCVD) system. In this paper, we report the spatial distribution of these plasma parameters in the chamber of this MPCVD system. And it is cleared that the plasma is very uniform in the chamber.

Oxidation Properties of Silicon Nitride Thin Films Fabricated by Double Tubed Coaxial Line Type Microwave Plasma Chemical Vapor Deposition

Silicon nitride films have been fabricated under different deposition conditions using a double tubed coaxial line type microwave plasma chemical vapor deposition system. The oxidation and annealing properties of the films have been analyzed using infrared absorption spectroscopy. It is shown that oxidation proceeds via (Si-H2)n bonds in the voids. During the process, hydrogen atoms are released. The N-H bonds which form the remainder in the bulk are not affected by oxidation. Based on this finding, films which have a large concentration of N-H bonds and a lower concentration of Si-H bonds show greater resistance to oxidation. Under adequate conditions, the stoichiometric oxidation-resistant silicon nitride films can be fabricated outside the discharge plasma even at room temperature.

二重管式同軸線路形マイクロ波プラズマＣＶＤにおけるＳｉＨ４の解離度と膜堆積速度

二重管式同軸線路形マイクロ波プラズマＣＶＤにおけるＳｉＨ４の解離度と膜堆積速度

Fabrication of a–Si:H films by coaxial line type microwave hydrogen plasma CVD

AbstractA double tubed coaxial line type microwave plasma CVD system has been developed for a‐Si:H film deposition using hydrogen and argon gases with pure SiH4 gas as the material gas. The film quality was evaluated as a function of the plasma condition.Since the spreads of hydrogen and argon plasmas were in the range of 2‐3 cm and 8‐9 cm, respectively, the substrate was placed 10 cm from the end of the discharge tube to avoid bombardment of the substrate by high‐energy particles. The film fabricated under hydrogen plasma showed superior characteristics. The film deposited at the substrate temperature between 150 and 200°C were of high quality; predominantly SiH bond rather than SiH2 bond, a large value for the photo‐dark conductivity ratio (σp/σd − 105) and a small density of dangling bonds.A high‐quality film can be fabricated under hydrogen plasma because a large amount of hydrogen radicals covers the film surface, thereby causing a thermal structural relaxation of silane radicals. This relaxation results when the silane radicals increase their surface mobility after the soft landing on the film surface.

二重管式同軸線路マイクロ波プラズマＣＶＤ法によるａ‐Ｓｉ：Ｈ薄膜の基板温度特性

二重管式同軸線路マイクロ波プラズマＣＶＤ法によるａ‐Ｓｉ：Ｈ薄膜の基板温度特性