Apparatus and method for reactive ion etching

The invention relates to an apparatus for reactive ion etching of a substrate, comprising: a plasma etch zone including an etch gas supply and arranged with a plasma generating structure for igniting a plasma and comprising an electrode structure arranged to accelerate the etch plasma toward a substrate portion to have ions impinge on the surface of the substrate; a passivation zone including a cavity provided with a passivation gas supply; said supply arranged for providing a passivation gas flow from the supply to the cavity; the cavity in use being bounded by the injector head and the substrate surface; and a gas purge structure comprising a gas exhaust arranged between said etch zone and passivation zone; the gas purge structure thus forming a spatial division of the etch and passivation zones

Long, lifetime, triggered, spark-gap switch for repetitive pulsed power applications

In this article a critical component for pulsed power applications is described: the heavy-duty switch. The design of a coaxial, high repetition rate, large average power, and long lifetime spark-gap switch is discussed. The switch is used with a fail-free LCR trigger circuit. Critical issues for switch design are presented together with experimental results. It is observed that the switch has a good stability, and its lifetime is estimated to be in the order of 1010 shots (~106 C) at 10 J/pulse, 60 kV and 100 ns pulses. Measurements were performed with 20 and 34 kV average switching voltage (100 ns pulses, energy per pulse 0.4 and 0.75 J, respectively). For up to 450 pulses/s (pps), pre-firing can be prevented by increasing the gap pressure (up to 2.5 and 7 bars, respectively), no gas flush is required. Above 450 pps, up to 820 pps, a forced gas flow of maximal 35 Nm3/h, is required for stable operation. Measurements on the time delay and jitter of the switch demonstrate that these values are influenced by pressure, flow, and pulse repetition rate. For 34 kV average switching voltage the time delay and time jitter vary between 35 and 250 and 10 and 80 µs, respectively. For 20 kV average switching voltage these values are: 30–160 and 4–50 µs. During a test run of 2.5 h (at 100 Hz, 0.75 J/pulse) the feasibility of the switch was proved, and the switching voltage jitter was less than 0.7%. ©2005 American Institute of Physic

Matching a pulsed power modulator to a corona plasma reactor

In this paper, the matching between the a pulsed power modulator and a corona plasma reactor is discussed. The matching is expressed as the energy transfer efficiency between the modulator and the reactor. The criterion for optimal matching between a source and a load is that the output impedance of the source is equal to the load impedance. When trying to match a pulsed power modulator to a plasma reactor this criterion is difficult to obey since the load impedance changes rapidly before, during and after plasma generation. To simulate the response of the load as function of the voltage pulse, an equivalent circuit is used. Measurements will be presented to verify the derived model. Guidelines to optimize the matching between the modulator and reactor are derived

Influence of pulse parameter on plasma generation and chemical efficiency of pulsed corona plasma technique

No abstrac

Investigation on a novel multiple-switch pulsed power technology

This paper discusses a novel multiple-switch pulsed power technology. By using transmission lines, multiple switches can be synchronized like in a MARX generator. To gain insight into this technology, an equivalent circuit model was developed, a two-switch experimental setup and a prototype pulsed power source with four gas spark- gap switches have been constructed. The four-switch setup includes 16 coaxial cables, four in parallel in each stage. This setup has been operated at a repetition rate of 50 pps with over 1.4 kA switching current. The principle, experimental setup and experiment results will be given in this paper

Exploring streamer variability in experiments

Abstract only

An efficient, repetitive nanosecond pulsed power generator with ten synchronized spark gap switches

This paper describes an efficient, repetitive nanosecond pulsed power generator using a Transmission-Line-Transformer (TLT) based multiple-switch technology. Within this setup, a 10-stage TLT and ten high-pressure spark-gap switches are adopted. At the input side, ten spark-gap switches are interconnected in series via the TLT, so that all the spark-gap switches can be synchronized automatically. At the output side, all the stages of the TLT are connected in parallel, thus a low output impedance (5 ¿) is obtained, and a large output current is realized by adding the currents through all the switches. Experimental results show that 10 spark-gap switches can be synchronized within about 10 ns. The system has been successfully demonstrated at repetition rates up to 300 pps (Pulses Per Second). Pulses with a rise-time of about 11 ns, a pulse width of about 55 ns, an energy of 9-24 J per pulse, a peak power of 300-810 MW, a peak voltage of 40-77 kV, and a peak current of 6-11 kA have been achieved with an energy conversion efficiency of 93-98

A high-temperature pulsed corona plasma system for fuel gas cleaning

Tars in fuel gases create serious obstacles for gasification. This paper describes a pulsed corona plasma system for tar removal from the fuel gas. Experiments were performed under gaseous temperatures of up to 500°C. Effects of the gaseous temperature on the electrical matching and tar removal are reported