A method and system for controlling electron densities in a plasma processing system. By applying a dither voltage and a correction voltage to a voltage-controlled oscillator, electron (plasma) density of a plasma processing system (acting as an open resonator) may be measured and controlled as part of a plasma-based process.

Stabilized oscillator circuit for plasma density measurement

A system for measuring plasma electron densities (e.g., in the range of 10?10 to 1012 cm-3?) and for controlling a plasma generator (240). Measurement of the plasma density is essential if plasma-assisted processes, such depositions or etches, are to be adequately controlled using a feedback control. Both the plasma measurement method and system generate a control voltage that in turn controls the plasma generator (240) to maintain the plasma electron density at a pre-selected value. The system utilizes a frequency stabilization system to lock the frequency of a local oscillator (100) to the resonant frequency of an open microwave resonator (245) when the resonant frequency changes due to the introduction of a plasma within the open resonator. The amplified output voltage of a second microwave discriminator may be used to control a plasma generator (240).

Electron density measurement and plasma process control system using a microwave oscillator locked to an open resonator containing the plasma

A method and system for measuring at least one of a plasma density and an electron density (e.g., in a range of 10?10 to 1012 cm-3?). Measurement of at least one of the plasma density and the electron density enables plasma-assisted processes, such as depositions or etches, to be controlled using a feedback control. Both the measurement method and system generate a control voltage that in turn controls a plasma generator (205) to maintain at least one of the plasma density and the electron density at a pre-selected value.

Electron density measurement and control system using plasma-induced changes in the frequency of a microwave oscillator

A system for measuring plasma electron densities (e.g., in the range of 1 010 to 1 01' cm-') and for controlling a plasma generator (320). Measurement of the plasma electron density is used as part of a feedback control in plasma-assisted processes, such as depositions or etches. Both the plasma measurement method and system generate a control voltage that in turn controls the plasma generator. A programmable frequency source (201) sequentially excites a number of the resonant modes of an open resonator placed within the plasma processing apparatus. The resonant frequencies of the resonant modes depend on the plasma electron density in the space between the reflectors of the open resonator. The apparatus automatically determines the increase in the resonant frequency of an arbitrarily chosen resonant mode of the open resonator due to the introduction of a plasma and compares that measured frequency to data previously entered. The comparison is by any one of (1) dedicated circuitry, (2) a digital signal processor, and (3) a specially programmed general purpose computer (100). The comparator calculates a control signal which is used to modify the power output of the plasma generator (320) as necessary to achieve the desired plasma electron density.

Electron density measurement and plasma process control system using changes in the resonant frequency of an open resonator containing the plasma

The configuration and performance of a Q-band injection-locked Gunn oscillator are presented whose outport is connected with a phase-locked reference source by a circulator. The output power of the oscillator is more than 60mW at 46.1GHz. The single-sideband phase noise (SSB) is less than-71.7dBc/Hz offset 10KHz from the carrier, and the spectrum of clutter signal is less than -40dB.

Q-band injection-locked gunn diode oscillator

The set up and the performance of a 94 GHz second harmonic Gunn oscillator that is cavity stabilized at its fundamental frequency is described. The cavity has a quality factor of about 7000 and reduces the phase noise by nearly 40 dB. The oscillator generates an output power of 40 mW, sufficient to drive low noise balanced mixers, to synchronize Impatt oscillators or to operate as a reference source in coherent radar systems.

H. Barth

Papers

A High Q Cavity Stabilized Gunn Oscillator at 94 GHz