Large-Area Electron Cyclotron Resonance Plasma Source with Permanent Magnets

Abstract

A large-area electron cyclotron resonance (ECR) plasma is generated by using permanent magnets and applying the whistler-mode launching of microwaves. A uniform plasma is produced with the uniformity of ±3.5% over 20 cm and ±1.8% over 16 cm in diameter; the plasma space potential is about 17 V with the uniformity of ±1% over 20 cm. The maximum ion current density is about 11.5 mA·cm-2. The purity of the produced plasma is high. No damage was found after the operation for 100 h with the microwave power of 600 W.

Influence on selective SiO2/Si etching of carbon atoms produced by CH4 addition to a C4F8 permanent magnet electron cyclotron resonance etching plasma

“…From Langmuir probe diagnostics of pure Ar gas in this region, T e and the plasma density (n e ) were approximately 3 eV and 1.0 ϫ 10 11 cm Ϫ3 , respectively. 4 The gradient and curvature of the permanent magnet magnetic field provide particle drift and diffusion in the downstream region that produces a uniform and a low temperature plasma. It has been shown in a previous report that such low T e values produce low energy controlled dissociation kinetics compared to conventional electromagnet ECR plasma sources.…”

“…In achieving such a low pressure etch process, a wide variety of high density plasma sources are being employed. [1][2][3][4] Etch selectivity is determined by the plasma chemistry and plasma-material interaction processes, hence understanding the plasma chemistry and the kinetics involved is vital for achieving the required selectivity. For the selective etching of silicon dioxide ͑SiO 2 ) over silicon ͑Si͒, a wide range of complex chemistries using various feed gases such as CHF 3 , CF 4 , C 2 F 6 , and C 4 F 8 have been employed 3,5-11 both with and without additions of Ar, H 2 and O 2 .…”

“…In this article, to understand in more detail the effect of carbon and carbon products on the etch process of SiO 2 over Si, diagnostics of the fluorocarbon radical species along with carbon and fluorine atom densities in a large-area permanent magnet ECR etching plasma employing C 4 F 8 gas with the addition of CH 4 are described. CH 4 was chosen because CH 4 is a source of carbon and hydrocarbon radicals similar to those species produced form the photoresist during etching. The addition of CH 4 to C 4 F 8 ECR plasma has enabled us to measure for the first time, to the best of our knowledge, the carbonatom density in an etching plasma.…”

“…Influence on selective SiO 2 /Si etching of carbon atoms produced by CH 4 addition to a C 4 F 8 permanent magnet electron cyclotron resonance etching plasma Shoji Changes in the densities of fluorocarbon radicals and fluorine atoms in a size-scalable large-area compact permanent magnet electron cyclotron resonance etching plasma source employing C 4 F 8 gas with CH 4 addition have been investigated. Measurements using infrared laser absorption spectroscopy and actinometric optical emission spectroscopy show that, for a pure C 4 F 8 plasma, the dominant species is CF 2 radicals with a density of the order of 10 13 cm Ϫ3 , followed by fluorine atoms, CF 3 and CF 2 radicals which have a density an order of magnitude lower at 10 12 cm Ϫ3 .…”

Production of Large-Diameter Uniform Plasma in mTorr Range Using Microwave Discharge

“…In discharges in the microwave frequency range, the use of cyclotron resonance of electrons with radiated fields from a slotted planar antenna has produced uniform plasmas of densities ranging from 10 10 to 10 11 cm −3 at pressures in the mTorr range. [1][2][3] The magnetic field necessary for resonant interaction is produced by an array of permanent magnets in this type of plasma source.…”