Optimization of Discharge Parameters for a Flat-Type Radio-Frequency Glow Discharge Source Coupled to a Quadrupole Mass Spectrometer System

1996 ◽  
Vol 50 (4) ◽  
pp. 454-466 ◽  
Author(s):  
Charles R. Shick ◽  
R. Kenneth Marcus
Keyword(s):  
Glow Discharge ◽  
Radio Frequency ◽  
Mass Spectrometer ◽  
Ion Beam ◽  
Source Parameters ◽  
Ionization Source ◽  
Radio Frequency Glow Discharge ◽  
Mass Spectrometer System ◽  
Discharge Parameters ◽  
Spectrometer System

A radio-frequency (rf)-powered glow discharge (GD) atomization/ionization source for nominally flat sample types (>6 mm o.d.) has been designed and coupled to a commercial GD mass spectrometer system, the VG GloQuad. This source was evaluated and optimized for conducting as well as nonconducting samples. A parametric study has been conducted on this rf-GDMS system with respect to discharge power, Ar flow (cell pressure), limiting orifice plate (anode) diameter, and ion sampling distance. Analytical characteristics under the optimized source parameters—including stabilization times (5 min for conducting samples, 60 min for nonconducting samples); repeatability (overall internal <2% RSD, overall external <8% RSD employing ion beam ratios); quantification; and detection limits—were evaluated for both conducting and nonconducting samples.

Characterization of a Radio-Frequency Glow Discharge/Time-of-Flight Mass Spectrometer

1994 ◽  
Vol 48 (11) ◽  
pp. 1337-1346 ◽  
Author(s):  
D. P. Myers ◽  
M. J. Heintz ◽  
P. P. Mahoney ◽  
G. Li ◽  
G. M. Hieftje
Keyword(s):  
Kinetic Energy ◽  
Glow Discharge ◽  
Radio Frequency ◽  
Mass Spectrometer ◽  
Time Of Flight ◽  
Detection Limits ◽  
Operating Conditions ◽  
Discharge Time ◽  
Radio Frequency Glow Discharge ◽  
Flight Mass Spectrometer

A radio-frequency glow discharge/time-of-flight mass spectrometer (RFGD-TOFMS) has been developed by simple modification of the interface to an ICP-TOFMS. The work described here evaluates the interface and operating conditions of the RFGD-TOFMS. The ion optics which focus ions toward the entrance of the TOFMS are the same as those used in the original ICP-TOFMS instrument. By means of pin-shaped brass samples of varied lengths, the sample-skimmer distance in the RFGD-TOFMS has been optimized at 4 mm. The discharge pressure and power have been found to be optimal at 50–60 W and 0.3 Torr, respectively. The application of small negative potentials to the skimmer cone (extraction orifice) was found to improve signals marginally. However, higher negative potentials reduced both signal levels and resolving power. The skimmer potential also affects the final kinetic energy of the ions before their extraction into the TOFMS. At 0.3 Torr all ions extracted for mass analysis have approximately the same kinetic energy, which can be estimated in the orthogonal TOFMS. Detection limits for several standard samples are at the single-ppm level, which is not unexpected; with the same ion-optical system, the current ICP-TOFMS also produces detection limits that are 2–3 orders of magnitude worse than those of many commercial instruments.

The Influence of Doping on the Etching of Si(111)

1986 ◽  
Vol 75 ◽  
Author(s):  
Harold F. Winters ◽  
D. Haarer
Keyword(s):  
Mass Spectrometer ◽  
Doping Level ◽  
Etch Rate ◽  
Plasma Reactors ◽  
Doping Effects ◽  
Mass Spectrometer System ◽  
Spectrometer System

AbstractIt has been recognized for some time that the doping level in silicon influences etch rate in plasma environments[1–8]. We have now been able to reproduce and investigate these doping effects in a modulated-beam, mass spectrometer system described previously [9] using XeF2 as the etchant gas. The phenomena which have been observed in plasma reactors containing fluorine atoms are also observed in our experiments. The data has led to a model which explains the major trends.

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