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Vacuum heaters, heating elements, hot stages, single and multi wafer in vacuum heating, high vacuum and ultra high vacuum UHV wafer heating, UHV chamber baking, UHV wafer annealing, heater power supply unit.

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In vacuum substrate heating, vacuum heating elements, UHV heating, sample heating, hot stages, wafer annealing, UHV wafer heating, ceramic elements, graphite elements, pyrolytic graphite element, PG-PBN elements, pyrolytic boron nitride crucibles, carbon carbon composite elements, vacuum furnace insulation, high temperature materials, vacuum compatible materials, heater controller, heater power supply, substrate heater controller.

We can offer a range of solutions for in vacuum heating, substrate heating, wafer heating, baking and vacuum wafer annealing, using different types of vacuum heaters and in vacuum heating elements. The pictures above show some of our standard range of ceramic topped resistance heating elements and hot stages. These have an element temperature of up to 1000C with NiCr element or 1600C with graphite element in high vacuum, and offer a cost effective reliable method of in vacuum sample heating. Our hot stages can mount onto a standard CF40 flange and are available with sample rotation, Z-shift movement, DC bias and RF bias options. We can also offer other methods of in vacuum heating, including flat and tubular resistance elements made from graphite, pyrolytic graphite, PG, carbon carbon composite, ccc, pyrolytic boron nitride, pbn, refractory metal and also halogen lamp heaters.

The pictures below show our plain high density graphite and carbon carbon composite (CCC) heating elements for low vacuum applications and for high vacuum, ultra high vacuum (UHV) or corrosive environments our silicon carbide, pyrolytic boron nitride (PBN) or pyrolytic graphite (PG) coated high density graphite and carbon carbon composite elements, in addition we supply our ultra low mass solid state pyrolytic boron nitride / pyrolytic graphite (PG/PBN) composite ceramic elements. All of these elements are suitable for in vacuum substrate heating or wafer annealing.

In addition to our ceramic topped heater range and basic elements in graphite, carbon carbon composite, pyrolytic graphite  and ceramic PBN-PG, we also manufacture power supplies and heater controllers, as well as bespoke vacuum furnaces and wafer annealing systems. The photographs below show our power supply and temperature controller range, and our 2000°C vacuum furnace.

Please contact us directly to discuss your vacuum substrate heating requirement in more detail so that we can offer the best solution for your application. All of our substrate heaters can be manufactured / modified to suit individual requirements, and we specialise in producing one off bespoke substrate heaters. Below we detail the different types of our vacuum substrate heaters, their properties and characteristics. We also manufacture a power supply to power our halogen heaters and ceramic topped resistance elements. Details of this are also shown below:-

Ceramic Toped Resistance Element

Our most cost effective and versatile substrate heating element, is UHV compatible can be run in air up to 1000C and in any orientation and is not effected by deposition product. It is very uniform and ideal for single wafer heating or wafer annealing, either radiating onto a substrate or by placing the wafer directly onto the ceramic top plate. Can be supplied with central hole for stage shaft to pass through. Max element temperature is 1000 deg C using NiCr element or up to 1600C (500C if O2 present) with a graphite element. Size range is from Ø2" to Ø12" (ceramic top plate diameter). Standard element is supplied with M6 central mounting stud on back of element casing. Options include secondary heat shields and water cooled outer heat shield. Can be used as a direct replacement for halogen heaters running off the same power supply. Element resistance and power requirement can tailored to suit existing power supplies. This element can be powered by our Ceramisis sample heater controller detailed below. Our ceramic topped NiCr element forms the basis of our standard 1000C deposition system hot stages, which mount onto a standard CF40 flange. These stages have a bayonet quick release sample holder and the options of: sample rotation, Z-shift movement for wafer transfer, DC bias for film modification, RF bias for wafer plasma cleaning and water cooled heat shields.

High Density Graphite Heating Element (Uncoated)

High density graphite elements are brittle, inexpensive and machined conventionally from large blocks, therefore very large sized elements can be produced in a variety of shapes and sizes. Our high strength ultra fine grained graphite enables small very intricate elements to be manufactured also. Graphite has a low expansion coefficient and is not degraded by constant heating and cooling, and also gets stronger as its temperature increases. Its low resistivity means it requires high current power supplies and therefore large feedthroughs and cables which can be expensive. It can operate over 2000 °C in an inert atmosphere, 1800°C in vacuum and <500°C if oxygen is present. Deposition product can cause electrical shorts and thus problems with supporting weak sagging element designs. Graphite has the ability to take very high current density, and therefore very fast ramp up times can be achieved. Its relatively high specific heat capacity means that cool down times in vacuum can be quite long. Apart from reacting with oxygen from 500C, graphite is otherwise very inert and can therefore operate in very corrosive or aggressive atmospheres without degradation. Particle contamination and open porosity can be a problem with graphite, but this can be overcome with coatings, or impregnations detailed below. Graphite elements are suitable for UHV applications, but must undergo initial out-gassing process due to its open porosity.

Carbon Carbon Composite (CCC) Heating Element (Uncoated)

Carbon Carbon Composite (CCC) has all of the properties of the high density graphite elements but it is much stronger and more robust. It still needs to be supported in larger diameters to avoid the element from sagging, and particle contamination and out gassing are still a problem. Very thin <1mm carbon carbon composite elements can be manufactured, giving the heater the benefit of low thermal mass and a higher resistance. CCC has very low thermal conductivity, which is beneficial in avoiding heat loss through power connection points. The raw material is manufactured in square plates with a limited maximum thickness of <30mm, therefore putting constraints on element designs.

Silicon Carbide, Pyrolytic Graphite, Vitreous Carbon and PBN Coatings, Plus Vitreous Carbon Impregnation On Graphite

To stop the problems of out gassing, particle contamination and oxidation that occurs with high density graphite and carbon carbon composite elements, there are various coatings that can be applied as follows: Pyrolytic Graphite Coating ( PG ): This can be applied by a CVD method to high density graphite and carbon carbon composite elements (see picture top left). It is still electrically conductive, but it totally seals the surface porosity and therefore traps any particles. Pyrolytic graphite coating is chemically the same as high density graphite and ccc and so will still react chemically in the same way and with oxygen at 500°C. PG coating is preferred by some for UHV applications, because it seals the open porosity of the graphite. However should the coating have a pin hole then the underlying graphite will take forever to outgas and thus act as a virtual leak. We therefore recommend uncoated graphite for UHV, as without the coating the graphite can initially outgas freely. PG coating would only be recommended for UHV if particle contamination was an issue. Vitreous Carbon Coating / Impregnation: Vitreous carbon surface treatment is a cheap alternative to pyrolytic graphite coating, and is produced by vitrifying a resin applied to the surface of the high density graphite component. It seals in the particles but does not totally seal the porosity, although it can be drastically reduced. Vitreous carbon coating is better at sealing the porosity than the impregnation and gives a nice black glassy appearance to the component. It is chemically the same as high density graphite and so will still react chemically in the same way and with oxygen at 500°C. Silicon Carbide Coating ( SiC ): Is a dark grey coating applied by a CVD method to specific grades of high density graphite. This silicon carbide ( SiC ) coating is an electrical insulator and therefore can not be applied to the electrical contact points on the element (see picture middle left). We can supply a SiC paint that can be applied to connection points after connection has been made. This paint is then thermally cured. The silicon carbide coating can operate in oxygen environments up to 1400°C and can resist some chemically corrosive environments better than graphite. Pyrolytic Boron Nitride Coating ( PBN ): This white Pyrolytic Boron Nitride coating can be applied to very specific grades of high density graphite (see picture bottom left) to seal the porosity and improve the oxidation and chemical resistance of the element. It will oxidise at 900°C if oxygen is present, but can withstand 2000°C in an inert atmosphere or vacuum (with N2 present).

Ceramic Pyrolytic Boron Nitride / Pyrolytic Graphite (PG/PBN) Composite Element

A very low mass (<1mm thick) fast response element with excellent chemical resistance and very high uniformity due to its layered pyrolytic structure. Its operating temperature is <900°C in Oxygen, >1500°C in vacuum or inert atmosphere (with N2 present). It is ideal for UHV environments and perfect for heating small samples < Ø1" which can be placed directly onto the element. Flat elements can be made up to Ø4" and cylindrical elements can also be manufactured. Element cost is high compared to ceramic topped resistance element. It is not greatly effected by deposition product. PG/PBN elements can be very unreliable and prone to delamination and therefore potentially have a short life span.

Halogen Heater

500w, 110v  ac single halogen bulb with stainless steel reflector. Is ideal for chamber baking or substrate heating. Supplied with L shaped mounting bracket on back of reflector housing. Is suitable for UHV applications and a single lamp is capable of heating a substrate to 400°C. Can provide very rapid heating with a very low thermal mass, therefore allowing heating to be stopped instantly, but performance can be greatly effected by deposition build up on halogen bulb.

Heater Controllers and Heater Power Supply

Our range of heater controllers and power supplies offer the complete solution to powering and controlling every possible kind of heating element. All our controllers are fitted with a Eurotherm 2216e PID temperature controller which enables the heater to be held at exactly the set temperature. A tuning facility enables the controller to accurately tune to the heaters requirements and therefore avoid overshooting during temperature ramping. The control enables ramping and cooling between two set points at a specified ramp rate. The heater controller can also be controlled remotely and integrated in system computer control programs via modbus RS232, RS485 and other protocols. All our heater controllers have power on / off switch to the whole unit, and an output enable switch to isolate the output from the controller. A 24v interlock circuit is also included to enable the power supply to be integrated with interlocks into other systems, or safety interlocks to be attached directly to the unit; which will switch off the output from the unit if the circuit is broken. This enables safety interlocks via make / break switches for things such as chamber lids closed, vacuum interlocks, cooling water flow, over temperature sensors etc. Our standard units are 50v or 115v burst-fire output (240v x 13 amp 50hz input). The 1kw unit is available in 3U x full 19" wide rack mount, or 3U half rack mount both with integrated transformer. Our 1.5kw unit is available in 3U half rack mount only. Above 1.5kw a separate transformer box is required. These units can be supplied with burst-fire thyristor or phase angle control thyristor which is more suitable for graphite elements.

 

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