PT7160 Plasma Barrel Reactor

An explanation of the plasma etching and plasma ashing process

The PT7160 plasma barrel reactor is designed to meet the requirements of research, development and small-scale production for a wide and varied range of plasma etching, plasma ashing and plasma cleaning applications. Built to withstand heavy use (24 hours a day for some ashing schedules) the PT7160 has semi-automatic operation and offers durability and simplicity of operation. Barrel systems plasma etch or plasma ash isotropically (in all directions) and are suitable for the majority of applications.

Key Features

150W power supply
Quartz chamber and window as standard
Auto tuning
Variable power level
Forward and reflected power meters
Twin gas flow meters
High throughput
EMC and LV compliant

Applications

Applications for this technique are extremely varied and this summary gives an indication of the type of problems it can help solve, for further information see the Applications page:

Asbestos and man made mineral fibre detection plasma ashing preparation techniques
UK Health & Safety Executive method for detecting man-made mineral fibre (including asbestos) (pdf file)
Removal of photoresist and epi-layers by plasma etching
Low temperature micro-incineration of organic materials (e.g. epoxies, filters, foodstuff, etc.)
Surface treatment of plastics for hydrophobic to hydrophilic conversion
Improving painting and inking characteristics of plastics
Plasma etching of organic samples for SEM and TEM examination.
Surface cleaning of samples
Plasma cleaning SEM, TEM and SPM parts

Features

Semi-automatic. Ease of operation and reproducibility from run-to-run. Ideal for small-scale plasma etching, plasma ashing and plasma cleaning production and research applications.
Auto tuning of RF power maintains conditions during plasma process, giving reproducibility from run-to-run. Processing times are faster because optimal operating conditions are maintained at all times. Auto-tuning also means easy operation – unlike cruder manual systems the user does not need to check power settings and re-tune during process runs.
Novel gas inlet system ensures even processing by spread of gas throughout the plasma etcher work chamber.
Monitoring of power and vacuum. The user has full control over operating parameters.
Capacitance Manometer (option). This replaces the normal Pirani gauge for vacuum measurement. If corrosive processing gases, such as CF₄, are to be used, the life of the Pirani gauge is considerably reduced. The optional capacitance manometer is not affected by corrosive gases.
Robust construction. Durable, long working life.

Single cabinet bench top construction

Three-range timer. Flexibility and precision.
Quartz chamber and door as standard. Suitable for corrosive plasma etching gases.
RF power supply "Trip" switch. Protects power supply from accidental misuse.
Fully interlocked. For safe operation.

Chamber and door At the heart of the PT7160 RF Plasma Barrel Reactor is a 10cm diameter x 15 cm long chamber horizontally mounted with a hinged door and RF shielded window. Both chamber and window are made of quartz, which is resistant to attack by corrosive gases, such as carbon tetrafluoride. The use of quartz prevents boron contamination of samples associated with "normal" borosilicate glass.	PT7160 plasma etcher chamber. Solenoid backed graduated gas flow meters allows precise mixing of two process gases.
The RF power in dissipated into the work chamber by four external copper electrodes	Inside the PT7160 work chamber. The optional PT7162 Temperature Monitor (centre of image) can be used to monitor the temperature of the substrate during plasma processing. To achieve a more representative reading the flexible sensor should be in contact with the substrate.
As with the chamber the door window is made of quartz glass. This prevents possible boron contamination, a potential problem with borosilicate glass.	The free floating door means that sealing is fast and efficient.
PT7160 plasma etcher Front Panel

Pumping and process control

Evacuation of the chamber is achieved by an optional 90 l/m mechanical rotary vacuum pump. Ingress of the reactive gas is controlled by two built in flow-meters backed by solenoid valves. The distribution of the gas is evenly spread throughout the work chamber by a novel inlet system surrounding the front of the chamber.
RF power of up to 150 watts at 13.56 MHz is available and can be infinitely controlled and pre-set to required values. Automatic tuning ("auto-tuning") of forward and reflected power is standard. The is particularly useful for longer plasma etching and plasma ashing processes.

Forward power is indicated by a digital display, reflected power by a bar graph. A Pirani gauge monitors vacuum levels. Once system parameters have been set, subsequent operation is semi-automatic; one button initiates a sequence of pump down to a base pressure, followed by ingress of the chosen process gas (or gasses) at a pre-set rate. RF plasma excitation (for a period pre-set by the timer) is initiated. The process will terminate with the chamber being continuously pumped. Venting to atmospheric pressure ready for the next cycle is manual.

With operator safety in mind, the PT7160 pumps out the chamber before venting. This ensures that residual gas in the chamber is removed before the front entry door is opened.
During the plasma process the 'autotune' facility ensures that RF power is automatically impedance matched to any variation in system or loading. Processing conditions in the chamber are therefore maintained at their optimum; this is important as it results in faster reaction times, reproducibility of results and also protects the power supply during the RF cycle.

The PT7160 plasma etcher is presented in a single EMC & LV compliant bench mounted case. A complete a working system requires only the addition of a specified rotary pump. For safety reasons a fomblinised rotary pump (E5OOSGZ) is strongly recommended when applications involve the use of oxygen as a process gas. Fomblin oil (E5OO5Z) must be ordered with the pump.
Reactive process gases, such as CF₄, significantly reduce the life of the Pirani gauge, in such cases the optional PT7161 capacitance manometer for vacuum measurement is essential. The optional PT7162 temperature monitor is available for monitoring thermally sensitive samples.

Options

PT7160-90 Spares kit for PT7160
PT7161 Capacitance manometer required for use with halogenated gasses
PT7162 0-200^oC temperature monitor

Requirements

E5005G RV5. 90l/min 115-230V 50-60Hz rotary vacuum pump with oil mist filter
E5005GZ RV5. 90 l/min 115-230V 50-60Hz fomblinised rotary vacuum pump with oil mist filter
E5004 Oil mist filter (additional)
E5005Z 1 kilo Fomblin oil