DE102008030679A1 - Device for the diffusion treatment of workpieces - Google Patents

Abstract

In a device for the diffusion treatment of workpieces, which comprises an outer chamber, wherein within the outer chamber at least one reaction region is arranged with means for evacuation, means for supplying gas and means for heating the first reaction region, it is proposed that the means for gas supply is formed flat and is arranged at a small distance and parallel to the substrate plane, so that the reaction region is limited in the operation of the device on one side by the means for gas supply and on the other side by a workpiece to be treated.

Description

following is a device for the diffusion treatment of workpieces, for example in the production of an absorber layer for photovoltaic energy converters, described.

The Implantation of foreign atoms of a so-called dopant in a Layer or in the base material of an electronic component or an integrated circuit is made to the properties this layer, mostly the conductivity or the crystal structure, to change specifically. There is this various methods, e.g. B. diffusion, resublimation from the gas phase, Co-evaporation, co-deposition or high-energy bombardment Particle guns (ion implantation). For example, atoms become atoms of the dopant in so-called diffusion furnaces at high temperatures introduced into the semiconductor material to selectively the electrical conductivity or to influence the mechanical properties of the material. Some Such processes take place at a pressure that is lower as the atmospheric pressure at normal conditions.

photovoltaic Energy converters, which are also referred to as solar cells, are electronic components that direct the energy of sunlight convert into electrical energy. After its construction differs thick-film and thin-film solar cells. Thin film solar cells point frequently a multilayer structure, wherein the energy conversion in the so-called absorber layer takes place, which usually consists of one so-called compound semiconductor is made. Compound semiconductor with high absorption capacity how the chalcopyrites, a group of I-III-VI compounds, become as absorber in thin-film photovoltaic modules with efficiencies over 10% already industrially produced. As a semiconductor for photovoltaics In addition to CuInS2, CuInSe2 and its derivatives Cu (In, Ga) S2 are predominantly CuInSe2 or Cu (In, Ga) Se2 used. As monovalent element is next Copper is also silver, as trivalent elements besides indium and gallium as well Aluminum and iron, and as hexavalent elements in addition to sulfur also used selenium and tellurium. By changing the composition, the Lattice constant and the band gap of the semiconductor in certain Limits are set.

to Production of a thin-film solar cell on a carrier substrate, For example, flat glass, the required layers sequentially deposited. The backsides Contact, for example, by a first electrode in the form of a molybdenum layer be formed from 500 to 1000 nm thickness, in a sputtering process directly on the carrier substrate was applied. The absorber layer can by simultaneous Sputtering of copper with gallium or / and indium and subsequent doping be prepared with selenium or / and sulfur, with selenium or / and High-temperature sulfur from the gas phase of H2Se or H2S is deposited. Subsequently becomes as a second electrode a transparent front contact layer produced. Between the individual layers mentioned here can be more Layers can be arranged on which no further at this point will be received.

at known diffusion furnaces The diffusion process takes place in a diffusion chamber, simultaneously several functions, namely the provision of a gas-tight separated from the atmosphere Reaction area, providing a process atmosphere in the Reaction zone, optionally below a lying below the atmospheric pressure Process pressure, the generation of the process temperature in the reaction area as well as the thermal insulation of the Reaction area opposite the atmosphere to maintain the process temperature prevailing in the reaction zone realized.

at a device for the diffusion treatment of workpieces, the an outer chamber includes, being inside the outer chamber at least one reaction zone with evacuation means, means for gas supply and means for heating the first reaction area is arranged, it is proposed that the means for gas supply formed flat is and arranged at a small distance and parallel to the substrate plane is so that the reaction area in the operation of the device on a Side by the means for gas supply and on the other side by a workpiece to be treated is limited.

The flat The means of gas supply provided ensure that in the area of the treated surface of the workpiece, at which the diffusion process is to be carried out, a process atmosphere with the required Concentration and composition is present. At the same time contamination of the reaction atmosphere prevailing in the process atmosphere thereby prevents the pressure conditions in the reaction area in relation to to the outside the reaction area prevailing pressure can be influenced. So long the pressure of the process atmosphere above the surface of the substrate is larger as the outside the reaction area prevailing pressure, the penetration of Impurities effectively prevented.

It can further be provided that the reaction area is enclosed by heat-insulating elements which are designed in such a way that the workpieces enter and leave the area enclosed by the heat-insulating elements can be transported. Such thermal insulation elements are preferably made of materials that can withstand very high temperatures and inert to process gases. It may be, for example, plates or moldings made of ceramic materials. It is not absolutely necessary that the thermal insulation elements are connected to each other so gas-tight that they form a reaction chamber. It is sufficient that the heat-insulating elements cooperate so that a large part of the heat generated by the means for heating remains in the reaction area.

The thermal insulation panels can continue to be designed so that a thermal insulation element at the same time Means for gas supply is. This can be achieved, for example be that a thermal insulation element has a centrally located gas outlet or a plurality of distributed gas outlets, if the requirements regarding a homogeneous feed of process gas are not very high. Alternatively, the relevant thermal insulation element as a plate with nozzle-shaped gas outlets or as areal connected arrangement of one (for example, meandering) or more tubes be designed with nozzle-shaped gas outlets, wherein the tubes are parallel to the transport direction of the substrates or can be arranged transversely to it. In a further embodiment, it is provided that the thermal insulation element from gas permeable made of ceramic material.

The Process gas flows from the through the workpiece surface and the areal trained means for supplying gas over the edges of the workpiece from. By suitable design of the geometric conditions, Dimensioning of the gas volume flow and the pressure is the flow velocity adjustable within wide limits. According to the respective requirements becomes the flow velocity adjusted so that the addition of contaminants against the Process gas flow is prevented.

By the segmentation of the means for gas supply in the transport direction, for example, in an embodiment as an arrangement of a plurality of tubes, results in the possibility the semiconductor layer in dependence from the location different process gas concentrations (ratio doping gas (Reactive gas) / carrier gas (Inert gas)). This results in the possibility of the semiconductor layer an optimized process gas atmosphere and temperature, which greatly extends the process optimization potential.

The warranty the process gas purity on the underside of the substrate is not mandatory required if by the measures described above the process gas purity on the substrate top with the sensitive Semiconductor layer ensured can be. Advantageously, the operation is designed at low Process pressures, because of that Operation at high process pressures comparatively low gas flows are sufficient to allow a sufficient flow rate. A viscous flow is beneficial to prevent the ingress of contaminants.

Thereby the purity of the process gas atmosphere at the process site is exclusively determined by determines the purity of the stored process gas.

Provided the influence of residual gases and contaminants contained in the process gas on achieving the desired Semiconductor properties negligible is operating even at lower pressures in the range of molecular flow in Question. The carrier gas flow rate can be reduced. The possibility, the operation without carrier gas to ensure, can not be excluded.

It results in the possibility outside the actual process gas atmosphere above the semiconductor layer also described above To use materials that are the release of unwanted Contaminants or reaction products are considered to be non-critical have to. The durability, in particular the high-temperature resistance of the materials outside the process zone opposite The process media used must be guaranteed.

The Means for heating the reaction region are useful in the from the thermal insulation elements arranged enclosed area. For example, the Means for heating the reaction area above the substrate plane be arranged. According to one Embodiment may be provided that a means for heating at the same time is a means for gas supply. This means that the Functions of means for heating and means for gas supply combined in one component. This makes it possible to do that preheat the process gas entering the reaction zone to this way an even more homogenous temperature distribution within of the reaction area. In a further embodiment can be provided that a means of heating on the means opposite to the gas supply Side of the substrate plane is arranged.

To heat the process zone radiators are used, which can withstand the process gas atmosphere. Advantageously, electrical resistance heaters can be used with quartz sheath. Conventional jacket tube heaters can be used, provided that they are aggressive pro Zessgasen can be protected, z. B. by flushing with inert gases. Radiation shield packages can be used for thermal insulation provided that the materials used resist the corrosive process gases. Furthermore, highly porous, heat-insulating ceramic materials can be used, which withstand the process gas atmosphere. Also come insulating packages, consisting of ceramic fiber materials in question.

It is technically limited possible, the thermal insulation to execute so densely that ensures a gas-tightness can be. A large number of openings in the insulating jacket for transport components, Heating throughs, Gas connections, suction, Pyrometer openings, etc. are imperfectly sealed by technical means.

By the additional Inert gas enters the room through the tank wall the outer chamber on the one hand and through the thermal insulation elements formed heating tunnel on the other hand, it is possible, a Inert gas flow over the constructive conditional gaps between feedthroughs and breakthrough openings to maintain in the interior of the insulating jacket. This will the passage of process gas through design-related columns from the heating tunnel room into the space between heating tunnel and tank wall effectively prevented. This will ensure that an impurity the components outside the heating tunnel is prevented. Elaborate cleaning work as well as the burden of the staff with reaction and decomposition products such as As particulate matter during maintenance work accounts or at least be considerably reduced.

Around the process gas atmosphere is not to disturb at the processor by the measures mentioned, is it is necessary to inject the inert gas flow which penetrates into the heating tunnel constructive measures so divert or diffuse that the gas pulse is not is more sufficient to enter the process gas atmosphere between the semiconductor layer and gas shower (gas supply means). This results the opportunity all process gases, residual gases and contaminants resulting from the operation dissipate. Deposits of unwanted Reaction and decay products throughout the room within the container walls the outer chamber become largely due to the measures mentioned prevented or reduced.

to execution several different diffusion processes on the workpieces can be further provided that in the outer chamber at least a second Reaction area, for example a reaction chamber, with means for evacuation, means for gas supply and means for heating of the second reaction region is provided and that between two successive reaction areas a transfer area, for example a transfer chamber, with means for evacuation and means for Gas supply is arranged.

If the reaction areas are realized by reaction chambers, so can at the inlet and outlet openings the reaction chambers may be provided for closing the same, However, it may be in a suitable embodiment of the device for atmosphere separation also be sufficient in the area of the inlet and outlet openings the reaction chambers means for evacuation and / or gas showers and / or other appropriate means. If at the inputs and outlet openings the reaction chambers provided means for closing the reaction chambers are, so can these may be designed, for example, as flap valves.

By the arrangement of a transfer area between two consecutive Reaction areas it is possible the workpieces from one reaction zone to a subsequent reaction zone move without the workpieces in between exposure to the ambient atmosphere. In this way Contamination of the workpieces is avoided in the workpieces the heat energy stored in the preceding diffusion process is for the subsequent Diffusion process mostly get and carry out several Diffusion processes can be done in a continuous process and thus easier faster and cheaper as in known devices for diffusion treatment.

In Embodiments of the proposed device is provided that before the first reaction area and / or after the last reaction area a transfer area is arranged. The one before the first reaction area arranged transfer area allows it, workpieces to provide it in time so that it does not interfere with in the respective reaction region prevailing process atmosphere in the Reaction area can be introduced once the previously in it treated workpieces were removed from the reaction area. The arranged after the last reaction area Transfer area represents a buffer area for the workpieces, have passed through all the reaction areas before these from the Device are removed.

In a further development of the device described, it is proposed that an outer chamber enclosing all reaction chambers is provided with an inlet lock and an outlet lock and with means for evacuation, before, behind and between the reaction chambers de areas forming the transfer chambers. In other words, an outer chamber is to be provided, in the interior of which all reaction chambers are arranged, for example, next to one another or one behind the other, that the free spaces remaining between them act as evacuatable transfer chambers. With a corresponding design of the outer chamber in relation to the arrangement of the reaction chambers in its interior, this can lead to all the free spaces which are located in front of, between and behind the reaction chambers, acting as transfer chambers. In this case, for example, the means for evacuating the outer chamber can be arranged between two transfer chambers, so that these means for evacuation effect the simultaneous evacuation of the adjacent transfer chambers.

Further it can be provided that the outer chamber means for gas supply having. In one embodiment of the device, it is provided that the means for supplying gas into the outer chamber are formed that in the area of the inlet opening and / or outlet opening At least one reaction chamber gas outlets are provided. hereby Is it possible, the workpieces before the first or / and between two consecutive and / or to rinse with a purge gas after the last diffusion process. In a further embodiment of the Device are the gas outlets the means for supplying gas into the outer chamber separately controllable, so that purge gas is issued only at the places and at the times, where there are workpieces be transported past.

To the Transport of workpieces a transport device can be provided by the device be, for example, two or more independently controllable Sections may have. This allows multiple workpieces or several batches of workpieces, which are at the same time inside the device, independently of each other between two sections of the device, for example one Reaction chamber and a transfer chamber, moved back and forth or if necessary, be kept in such a section to them to suspend a diffusion treatment or before the first or after the last diffusion process or between two diffusion processes to store between.

To the Transport of workpieces Through the reaction areas (process zones) can be used for reasons of temperature and corrosion resistance over the Process media advantageous rolls or cylindrical rollers from a ceramic material are used.

It can further be provided that all reaction chambers in a the transport direction of the workpieces Having seen through the reaction chamber have rectangular cross-section. On the one hand, this means larger cross sections representable as the usual, formed from a quartz tube reaction chambers, so that the to be treated workpieces be much larger can than when using known diffusion furnaces. This will become that evacuating volume of the reaction chamber and the required volume to reactive gas, based on the treatable material surface per Batch, significantly reduced.

there can be further provided that the reaction chambers of even Quartz or ceramic plates are limited. In the event that the transfer chambers are arranged between the reaction chambers, the quartz plates must at their for the atmosphere facing outer surfaces by supporting structures, for example, the quartz plates enclosing steel plates, be wrapped so that the quartz plates the pressure difference between the atmosphere and the can withstand pressure prevailing in the reaction chamber, if this is much lower than the atmospheric pressure. If, however, one outer chamber is provided, which completely encloses the reaction chambers and the For its part, it can be evacuated, so it is not necessary, such support structures in this case, both inside and outside the reaction chamber of the same pressure prevails and thereby flat quartz plates of the influence of a possibly remaining Can withstand pressure difference.

In a further embodiment of the proposed device provided that all the reaction chambers through the means of evacuation the outer chamber are evacuated. The structural complexity of the device is reduced This is clear because no dedicated vacuum pumps for each one Reaction chamber needed become. However, if reaction chambers have their own vacuum pumps, so it can be provided that the means for evacuating each reaction chamber separately are controllable, making it possible is the vacuum conditions within each reaction chamber different, for example, to the in the to adapt to the respective reaction chamber diffusion process.

to Better adaptation of the process conditions to those in the respective Reaction chamber occurring diffusion process can continue be provided that the means for gas supply to each reaction chamber and / or the means for heating each reaction chamber separately are controllable. Furthermore For example, the device described may be designed such that the means for heating at least one reaction chamber on the outside the reaction chamber are arranged.

following the invention with reference to an embodiment and an accompanying drawing explained in more detail. there demonstrate

1 an exemplary embodiment of the device described in longitudinal section,

2 the embodiment of 1 in cross section,

3 a second embodiment in a plan view,

4 a third embodiment in a plan view,

5 a third embodiment in a plan view.

The Illustration of the different plant components is in the figures highly schematized and should not be understood in any way limiting. For example, it is readily apparent to those skilled in the art, such as designed and arranged the means for heating the reaction areas can be one as possible uniform temperature distribution to achieve. You can do this For example, the means for heating be formed flat. In analog Way it is a routine job for the professional, the form and Arrangement of other components, such as the means of evacuation, means to make the gas supply, transport device, etc. so that the desired Result is achieved.

In the embodiment of a device for the diffusion treatment of workpieces, as in 1 and 2 is shown in an outer chamber 1 with an entrance lock 13 and an exit lock 14 a reaction area 2 arranged to perform a diffusion process.

In front of and behind the reaction area 2 are transfer areas 16 educated. They will pass through the respective front and back of the reaction area 2 lying sections of the outer chamber 1 represented as the outer chamber 1 self evacuated.

For this purpose are in the areas of the outer chamber 1 that the transfer areas 16 form, means of evacuation 11 arranged. Furthermore, in the outer chamber 1 immediately before and after the reaction area 2 Means for gas supply 12 provided, which are formed so that in the region of the inlet opening and outlet opening of the reaction area 2 Gas outlets are provided. As a result, the workpieces are rinsed with a purge gas before and after the diffusion process. The means of evacuation 11 and the means for gas supply 12 the outer chamber 1 are separately and independently controllable. The pollution in the reaction area 2 formed process atmosphere is prevented by that in the reaction area 2 generated pressure is greater than that in the transfer areas 16 prevailing pressure.

The reaction area 2 is from an upper thermal insulation element 4 and a lower thermal insulation element 4 enclosed in such a way that the workpieces can be transported in and out of the area enclosed by them. The reaction area formed therein 2 has separately and independently controllable means of evacuation 21 and means for gas supply 22 on. Inside of the thermal insulation elements 4 enclosed area are still means of heating 23 of the reaction area 2 arranged.

The reaction area 2 forms between the surface of the workpiece to be treated 5 and the one or more arranged over it, surface-shaped means for gas supply 22 out. The workpiece to be treated 5 is moved through the device on a substrate plane. Below this substrate level are means for heating 23 arranged, which are executed in the embodiment as a surface radiator. Furthermore, also below the substrate level, means for evacuation 21 arranged that out of the reaction area 2 over the edges of the workpiece 5 The gas flowing out. The gas from the means for gas supply 22 and the surface of the workpiece 5 formed reaction area 2 as well as the means for heating 23 are a total of several plate-shaped, formed of a ceramic material thermal insulation elements 4 enclosed, thus forming a heating tunnel, which reduces the loss of heat generated by the means for heating. These thermal insulation elements 4 However, they are not arranged to each other so that thereby a gas-tight reaction chamber is formed.

Furthermore, a transport device 15 provided for the transport of the workpieces by the device, which comprises an arrangement of successive transport rollers made of a ceramic material whose uppermost generatrix lines define the substrate plane. The transport device 15 extends through the entire outer chamber 1 and through the reaction area 2 , where in the reaction area 2 lying transport rollers of the transport device 15 penetrate the space enclosed by the heat-insulating elements, so that on them the workpieces to be treated through the reaction area 2 can be transported.

In the plan view of the embodiments of the device in the 3 to 5 has been omitted for clarity, the presentation of some components of the device to the basic structure of the reaction areas 2 inside the outer chamber 1 to clarify.

In 4 shows an embodiment of the apparatus for the diffusion treatment of workpieces, in which, similar to the device of the 1 and 2 , two reaction areas 2 are arranged linearly one behind the other. However, this device is modular. Each reaction area 2 is in its own outer chamber 1 arranged. Every outer chamber 1 has in front of the respective reaction area 2 over an area that is in operation of the device as a transfer area 16 acts. The outer chambers 1 are connected to each other so that they together form a vacuum container, in addition to the one to the second outer chamber 1 subsequent, separate transfer area 3 belongs. The entrance lock 13 the device is at the front end of the first outer chamber 1 attached while the exit lock 14 at the end of the separate transfer area 3 is appropriate.

The modular design allows a flexible configuration of the device, of course devices with only one or more than two reaction areas 2 possible are. In the same way, the arrangement of the transfer areas 3 . 16 be varied or individual transfer areas 3 . 16 enlarged or omitted. The transfer areas 16 can also be used exclusively as separate transfer chambers 3 be executed, so that each outer chamber 1 only slightly larger than the reaction area arranged therein 2 ,

In the embodiment in 3 again it is the arrangement of two reaction areas 2 within a common outer chamber 1 but where the reaction areas 2 are arranged next to each other, so that between the reaction areas 2 a change of the transport direction of the substrates takes place. This is the entrance lock 13 and the exit lock 14 the device side by side on the same side of the outer chamber 1 arranged.

Similarly, in the embodiment in FIG 5 three reaction areas 2 within a common outer chamber 1 juxtaposed so that between the first and second reaction area 2 and between the second and third reaction areas 2 a change of the transport direction of the substrates takes place. As a result, in this embodiment, the entrance lock 13 and the exit lock 14 the device on opposite sides of the outer chamber 1 arranged.

1

outer chamber

11

medium for evacuation

12

medium for gas supply

13

entry lock

14

exit lock

15

transport means

16

Transfer Section / transfer chamber

2

Reaction zone / reaction chamber

21

medium for evacuation

22

medium for gas supply

23

medium for heating

3

separate transfer chamber

4

thermal insulation element

5

workpiece

Claims (29)

Device for the diffusion treatment of workpieces, comprising an outer chamber ( 1 ), whereby within the outer chamber ( 1 ) at least one reaction area ( 2 ) with means for evacuation ( 21 ), Means for gas supply ( 22 ) and means for heating ( 23 ) of the reaction area ( 2 ), characterized in that the means for supplying gas ( 22 ) is formed flat and is arranged at a small distance and parallel to the substrate plane, so that the reaction region ( 2 ) in the operation of the device on one side by the means for gas supply ( 22 ) and limited on the other side by a workpiece to be treated. Apparatus according to claim 1, characterized in that the reaction area 2 of thermal insulation elements ( 4 ) is enclosed so that the workpieces in the of the thermal insulation elements ( 4 ) enclosed area in and out of it can be transported out. Device according to one of claims 1 to 2, characterized in that a thermal insulation element 4 at the same time a means of gas supply ( 22 ). Device according to one of claims 1 to 3, characterized in that the thermal insulation elements 4 are designed so that a gas passage in the room, by the thermal insulation elements 4 and the outer chamber 1 is formed, is possible or in the opposite direction. Device according to one of claims 1 to 4, characterized in that the thermal insulation element 4 made of gas permeable ceramic material. Device according to one of claims 1 to 5, characterized in that the means for heating ( 23 ) of the reaction area ( 2 ) in which of the thermal insulation elements ( 4 ) enclosed area are arranged. Apparatus according to claim 6, characterized in that a means for heating ( 23 ) at the same time a means for gas supply ( 22 ). Device according to one of claims 6 to 7, characterized in that a means for heating ( 23 ) on the gas supply means ( 22 ) opposite side of the substrate plane is arranged. Device according to one of the preceding claims, characterized in that at least one further reaction region ( 2 ) with means for evacuation ( 21 ), Means for gas supply ( 22 ) and means for heating ( 23 ) of the second reaction chamber ( 2 ) and that between two consecutive reaction areas ( 2 ) a transfer area ( 3 . 16 ) with means for evacuation ( 11 ) and means for gas supply ( 12 ) is arranged. Device according to one of the preceding claims, characterized in that before the first reaction region ( 2 ) a transfer area ( 3 . 16 ) is arranged. Device according to one of the preceding claims, characterized in that after the last reaction region ( 2 ) a transfer area ( 3 . 16 ) is arranged. Device according to one of the preceding claims, characterized in that an all reaction areas ( 2 ) enclosing outer chamber ( 1 ) with an entry lock ( 13 ) and an outlet lock ( 14 ) and with means for evacuation ( 11 ), before, behind and between the reaction areas ( 2 ) lying areas the transfer areas ( 16 ) form. Device according to one of the preceding claims, characterized in that the outer chamber ( 1 ) further means for gas supply ( 12 ) having. Device according to one of the preceding claims, characterized in that the means for supplying gas ( 12 ) in the outer chamber ( 1 ) are formed so that in the region of the inlet opening and / or outlet opening of at least one reaction region ( 2 ) Gas outlets are provided. Device according to one of the preceding claims, characterized in that the gas outlets of the gas supply means ( 12 ) in the outer chamber ( 1 ) are separately controllable. Device according to one of the preceding claims, characterized in that a transport device ( 15 ) is provided for the transport of the workpieces by the device. Apparatus according to claim 16, characterized in that the transport device ( 15 ) has at least two independently controllable sections. Device according to one of the preceding claims, characterized in that all reaction areas ( 2 ) have a rectangular cross-section. Device according to one of the preceding claims, characterized in that all reaction areas ( 2 ) are limited by flat quartz or ceramic plates. Device according to one of the preceding claims, characterized in that all reaction areas ( 2 ) by means of evacuation ( 11 ) of the outer chamber ( 1 ) are evacuated. Device according to one of the preceding claims, characterized in that the means for evacuating ( 21 ) of each reaction zone ( 2 ) are separately controllable. Device according to one of the preceding claims, characterized in that the means for supplying gas ( 22 ) of each reaction zone ( 2 ) are separately controllable. Device according to one of the preceding claims, characterized in that the means for heating ( 23 ) of each reaction zone ( 2 ) are separately controllable. Device according to one of the preceding claims, characterized in that the means for heating ( 23 ) at least one reaction area ( 2 ) on the outside of the reaction zone ( 2 ) are arranged. Device for the diffusion treatment of workpieces, comprising an outer chamber ( 1 ), whereby within the outer chamber ( 1 ) at least one reaction area ( 2 ) with means for evacuation ( 21 ), Means for gas supply ( 22 ) and means for heating ( 23 ) of the reaction area ( 2 ), characterized in that the reaction region ( 2 ) of thermal insulation elements ( 4 ) is limited, that on the inner surface facing the workpiece a temperature required for the diffusion treatment can be adjusted and that on the outer to the outer chamber ( 1 ), a temperature is produced which is below the temperature at which thermal reactions of the process gas take place. Device according to claim 25, characterized in that the reaction region ( 2 ) of thermal insulation elements ( 4 ) is enclosed so that the workpieces in the of the thermal insulation elements ( 4 ) enclosed area in and out of it can be transported out. Device according to one of claims 25 to 26, characterized in that a thermal insulation element ( 4 ) at the same time a means for gas supply ( 22 ). Device according to one of claims 25 to 27, characterized in that the thermal insulation element ( 4 ) is made of gas-permeable ceramic material. Device according to one of claims 25 to 27, characterized in that the heat-insulating elements ( 4 ) are designed so that a gas passage in the space of the heat-insulating elements ( 4 ) and the outer chamber ( 1 ) is possible, or in the opposite direction.