Roland Gesche - Academia.edu (original) (raw)
Papers by Roland Gesche
2022 International Conference on Electronics Packaging (ICEP)
Disclosed is a method and an arrangement for dielectric heating of plastic pipes or other tubular... more Disclosed is a method and an arrangement for dielectric heating of plastic pipes or other tubular structures of any cross section of dielectric material described. At least one internal electrode is provided which is located in the interior of the plastic tube and at least two external electrodes, which surround the plastic pipe. The inner electrode is extended in the axial direction of the tube so that at least a partial overlap exists with at least two external electrodes. At least two external electrodes, a high frequency AC voltage is applied. The system external electrode-pipe internal electrode outer electrode forms a series arrangement of two capacitors whose dielectric is formed in each case by the plastic of the pipe wall. There is a dielectric heating in the region of overlap between inner and outer electrodes. This can eg. For example, be used to heat the tube for a bending operation.
Inductively coupled plasma (ICP) reactors are usually meter sized and driven at RF frequencies, f... more Inductively coupled plasma (ICP) reactors are usually meter sized and driven at RF frequencies, for example at 13.56 MHz. We developed a miniature resonator allowing an inductive type of coupling of microwaves at 2.45 GHz to a plasma jet, flowing in ceramic tubes. Previous experiments and simulations [1] show an efficient energy transfer of microwaves to plasma of about 80 %. The new development of our ICP structure contains two ceramic tubes and a symmetrical arrangement of two resonators. The present paper concentrates on a study of this plasma source, considering the complex interaction of the electromagnetic field with the plasma and the gas flow, using the plasma module of Comsol. This module gives a realistic picture when the gas pressure is higher than 1000 Pa but fails for values of 1...10 Pa, which is just our range of operation.
In the frame of the Facility for Antiproton and Ion Research (FAIR) 9 bunch compressor RF station... more In the frame of the Facility for Antiproton and Ion Research (FAIR) 9 bunch compressor RF stations were ordered for the first stage of realization of the SIS100 synchrotron. For RF gymnastics referred to as bunch rotation, one RF station has to provide a sudden rise in gap voltage of up to 40 kVp within less than 30 μs. The system is designed for a maximum RF burst of 3 ms per second. The RF frequency will be pre-selectable between 310 kHz and 560 kHz at a harmonic number of h=2 with respect to the beam. Compressed bunches with a peak current > 150 A and a width < 50 ns are the goal. For this purpose, a 1.218 m long cavity was designed using iron-based magnetic alloy cores. Variable vacuum capacitors are attached for tuning. The cavity is driven by a cross-coupled push-pull tetrode amplifier. This scheme minimizes the influence of the tetrode's DC current at the working point to the cores. The energy for the pulsed system is stored in a relatively small capacitor bank whic...
A sputter deposition process working at atmospheric pressure is demonstrated. Argon is ionized at... more A sputter deposition process working at atmospheric pressure is demonstrated. Argon is ionized at atmospheric pressure by a microwave microplasma source. A metallic gold target is placed close to the discharge and biased by a dc power supply. The V/I characteristics of the target to ground impedance show a stable behavior up to some hundreds of volts and some mA before it changes to an instable arc regime. In this stable region, ion flow and ion energy are suitable for sputtering. Target material is sputtered and the gold can be detected on a glass substrate placed close to the target. This proves the principal possibility to realize sputter deposition processes under atmospheric pressure for the first time. A first application can be a localized small-area metallization of insulating materials. Further developments and opportunities are discussed.
Physical plasmas which contain a mixture of different radicals, charged species and UV-radiation,... more Physical plasmas which contain a mixture of different radicals, charged species and UV-radiation, have recently found entry in various medical applications. Though first clinical trials are underway nothing is known about the plasma components mediating the biological effects seen and safety concerns have been neglected. We here use for the first time a plasma device equipped with a bent quartz capillary to omit UV-radiation by directing the gas flux only, containing high concentrations of NO, onto cultured human skin cells. This enables us to compare the effects of plasma produced radical species alone - mainly NO - and in combination with the also emitted UV-radiation on cells. Evaluation of cell death after different treatment times with the capillary present shows no sign of apoptosis in primary human keratinocytes even after 15 min plasma exposure. In human skin endothelial cells however, toxicity is elevated after treatment for more than 10 min. In contrast, without the capill...
The ignition process in microplasmas is characterized by time resolved microwave reflection coeff... more The ignition process in microplasmas is characterized by time resolved microwave reflection coefficient measurements, using a specially equipped vector network analyzer. We measured the time between the switching on of the microwave power and the onset of the plasma state in air at atmospheric pressures. The delay time decreases from approx. 3 ms to 60 μ s by increasing the microwave power from values just above the ignition threshold to higher values. A simple model shows the role of the free electrons in air and of the electrodes in the ignition process (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures
ABSTRACT This paper describes the first results of the new Leybold Leybold circular electron cycl... more ABSTRACT This paper describes the first results of the new Leybold Leybold circular electron cyclotron resonance (CECR) technology which uses circular polarized microwave excitation for generating a plasma of very high density. At a pressure of 1 μbar, an ion current density of 6 mA/cm2 was measured in a pure chlorine plasma. That reveals in fact an increase of about 30% in ion density compared to the linear polarized electron cyclotron resonance (ECR) source. The appreciable improvement will be demonstrated by etching results of silicon trench with chlorine where an etch rate of 300 nm/min with a uniformity better than ±5% on 200 mm wafer size was obtained. The source has a compact design which enables multichamber processing in a cluster tool environment with the capability for processing wafers up to 200 mm diameter.
2022 International Conference on Electronics Packaging (ICEP)
Disclosed is a method and an arrangement for dielectric heating of plastic pipes or other tubular... more Disclosed is a method and an arrangement for dielectric heating of plastic pipes or other tubular structures of any cross section of dielectric material described. At least one internal electrode is provided which is located in the interior of the plastic tube and at least two external electrodes, which surround the plastic pipe. The inner electrode is extended in the axial direction of the tube so that at least a partial overlap exists with at least two external electrodes. At least two external electrodes, a high frequency AC voltage is applied. The system external electrode-pipe internal electrode outer electrode forms a series arrangement of two capacitors whose dielectric is formed in each case by the plastic of the pipe wall. There is a dielectric heating in the region of overlap between inner and outer electrodes. This can eg. For example, be used to heat the tube for a bending operation.
Inductively coupled plasma (ICP) reactors are usually meter sized and driven at RF frequencies, f... more Inductively coupled plasma (ICP) reactors are usually meter sized and driven at RF frequencies, for example at 13.56 MHz. We developed a miniature resonator allowing an inductive type of coupling of microwaves at 2.45 GHz to a plasma jet, flowing in ceramic tubes. Previous experiments and simulations [1] show an efficient energy transfer of microwaves to plasma of about 80 %. The new development of our ICP structure contains two ceramic tubes and a symmetrical arrangement of two resonators. The present paper concentrates on a study of this plasma source, considering the complex interaction of the electromagnetic field with the plasma and the gas flow, using the plasma module of Comsol. This module gives a realistic picture when the gas pressure is higher than 1000 Pa but fails for values of 1...10 Pa, which is just our range of operation.
In the frame of the Facility for Antiproton and Ion Research (FAIR) 9 bunch compressor RF station... more In the frame of the Facility for Antiproton and Ion Research (FAIR) 9 bunch compressor RF stations were ordered for the first stage of realization of the SIS100 synchrotron. For RF gymnastics referred to as bunch rotation, one RF station has to provide a sudden rise in gap voltage of up to 40 kVp within less than 30 μs. The system is designed for a maximum RF burst of 3 ms per second. The RF frequency will be pre-selectable between 310 kHz and 560 kHz at a harmonic number of h=2 with respect to the beam. Compressed bunches with a peak current > 150 A and a width < 50 ns are the goal. For this purpose, a 1.218 m long cavity was designed using iron-based magnetic alloy cores. Variable vacuum capacitors are attached for tuning. The cavity is driven by a cross-coupled push-pull tetrode amplifier. This scheme minimizes the influence of the tetrode's DC current at the working point to the cores. The energy for the pulsed system is stored in a relatively small capacitor bank whic...
A sputter deposition process working at atmospheric pressure is demonstrated. Argon is ionized at... more A sputter deposition process working at atmospheric pressure is demonstrated. Argon is ionized at atmospheric pressure by a microwave microplasma source. A metallic gold target is placed close to the discharge and biased by a dc power supply. The V/I characteristics of the target to ground impedance show a stable behavior up to some hundreds of volts and some mA before it changes to an instable arc regime. In this stable region, ion flow and ion energy are suitable for sputtering. Target material is sputtered and the gold can be detected on a glass substrate placed close to the target. This proves the principal possibility to realize sputter deposition processes under atmospheric pressure for the first time. A first application can be a localized small-area metallization of insulating materials. Further developments and opportunities are discussed.
Physical plasmas which contain a mixture of different radicals, charged species and UV-radiation,... more Physical plasmas which contain a mixture of different radicals, charged species and UV-radiation, have recently found entry in various medical applications. Though first clinical trials are underway nothing is known about the plasma components mediating the biological effects seen and safety concerns have been neglected. We here use for the first time a plasma device equipped with a bent quartz capillary to omit UV-radiation by directing the gas flux only, containing high concentrations of NO, onto cultured human skin cells. This enables us to compare the effects of plasma produced radical species alone - mainly NO - and in combination with the also emitted UV-radiation on cells. Evaluation of cell death after different treatment times with the capillary present shows no sign of apoptosis in primary human keratinocytes even after 15 min plasma exposure. In human skin endothelial cells however, toxicity is elevated after treatment for more than 10 min. In contrast, without the capill...
The ignition process in microplasmas is characterized by time resolved microwave reflection coeff... more The ignition process in microplasmas is characterized by time resolved microwave reflection coefficient measurements, using a specially equipped vector network analyzer. We measured the time between the switching on of the microwave power and the onset of the plasma state in air at atmospheric pressures. The delay time decreases from approx. 3 ms to 60 μ s by increasing the microwave power from values just above the ignition threshold to higher values. A simple model shows the role of the free electrons in air and of the electrodes in the ignition process (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures
ABSTRACT This paper describes the first results of the new Leybold Leybold circular electron cycl... more ABSTRACT This paper describes the first results of the new Leybold Leybold circular electron cyclotron resonance (CECR) technology which uses circular polarized microwave excitation for generating a plasma of very high density. At a pressure of 1 μbar, an ion current density of 6 mA/cm2 was measured in a pure chlorine plasma. That reveals in fact an increase of about 30% in ion density compared to the linear polarized electron cyclotron resonance (ECR) source. The appreciable improvement will be demonstrated by etching results of silicon trench with chlorine where an etch rate of 300 nm/min with a uniformity better than ±5% on 200 mm wafer size was obtained. The source has a compact design which enables multichamber processing in a cluster tool environment with the capability for processing wafers up to 200 mm diameter.