DE102009012200A1 - Thermal conversion of metallic precursor layer into semiconductor layer in thin layer solar cell, involves introducing chalcogen vapor/carrier gas mixture on substrate having precursor layer, heating, converting and cooling - Google Patents

Abstract

An inlet and outlet side gas lock (4.1,4.2,4.3,4.4) for oxygen-tight closure of a furnace chamber (1) is formed. One or more substrates (6) prepared with at least one metallic precursor layer (7) are introduced into chamber. A chalcogen vapor/carrier gas mixture (10) is introduced on substrate. The substrate is heated in chalcogen vapor/carrier gas atmosphere to a final temperature and precursor layers are converted into semiconducting layers. The gas mixture not consumed in the reaction is removed, substrate is cooled and substrate is removed from chamber. An inlet and outlet side gas lock for oxygen-tight closure of a furnace chamber is formed. One or more substrates prepared with at least one metallic precursor layer are introduced into chamber. A chalcogen vapor/carrier gas mixture is introduced on substrate, and mixture is uniformly distributed along width of substrate. The substrate is heated in chalcogen vapor/carrier gas atmosphere to a final temperature and precursor layers are converted into semiconducting layers. The gas mixture not consumed in the reaction is removed, substrate is cooled and substrate is removed from chamber. An independent claim is included for device for thermal conversion of metallic precursor layer.

Description

at The present invention is a method and a device for the thermal conversion of metallic precursor layers on flat substrates in semiconducting layers.

For a cheap and environmentally friendly energy production By converting sunlight into electrical energy becomes one Production of highly efficient solar cells if possible low material and energy consumption needed. Promising here are thin-film solar cells, in particular solar cells based on compound semiconductors such as copper-indium-gallium-selenide (CIGS).

The Production of semiconducting layers takes place in a multi-stage Process. The metallic precursor layers can be copper (Cu), gallium (Ga) and indium (In), which are such as sputtering, onto the substrate, which is a glass substrate with a molybdenum layer (Mo) may be applied can. In a second step will be in a tempering process the metallic precursor layers in a chalcogen-containing atmosphere, preferably consisting of selenium and / or sulfur, in semiconducting Layers, preferably in a CuInGaSe (CIGS) layer, converted. The chalcogenes increase at room temperature, ie around 20 ° C, a solid state of aggregation.

such Substrates prepared with a semiconductive layer can then be further processed to solar modules. Essential for a good efficiency is the possible complete implementation of the metallic precursor layers into a semiconductive layer with the same layer thickness the area of the substrate.

To the prior art are methods for the thermal conversion of these prepared precursor layers in semiconducting layers become known, which take place in a vacuum. The problem with the vacuum processes is the long conversion time, also called process time. this leads to in industrial implementation problems, because long process times always accompanied by low productivity. A solution On the one hand, the use of many machines would be simultaneous, which would mean high investment costs, or on the other hand, the acceleration of the processes. Therefor However, the prior art provides no evidence.

Furthermore, the prior art has disclosed processes for the thermal conversion of these prepared precursor layers into semiconducting layers which proceed under atmospheric conditions and with the supply of hydrogen-containing gases, for example hydrogen selenide ( EP 0 318 315 A2 ). However, the use of toxic gases such as hydrogen selenide is problematic.

Out EP 0 662 247 B1 has disclosed a method for producing a chalcopyrite semiconductor on a substrate, wherein the substrate prepared with metals such as copper, indium or gallium in an inert process gas to a final temperature of at least 350 ° C at a heating rate of at least 10 ° C. / Second is heated up. The final temperature is maintained for a period of 10 seconds to 1 hour in which the substrate is exposed to sulfur or selenium as a component in excess of the components copper, indium or gallium. For this purpose, a cover at a distance of less than 5 mm in the sense of an encapsulation is located above the layer structure on the substrate. As described in the patent, the partial pressure of sulfur or selenium is above the partial pressure which would form over a stoichiometrically exact composition of the starting components copper, indium or gallium and selenium or sulfur in the ratio 1: 1: 2. However, no oven segmented into different temperature ranges suitable for a continuous process is described.

In the post-published international patent application PCT / EP 2008/007466 is an easy to implement, rapid flow method for the thermal conversion of metallic layers on any substrates in semiconducting layers, as well as an appropriate device for performing the method indicated.

Reached This is done with a process in which the at least one metallic Precursor layer prepared substrates in one in different Temperature ranges segmented oven at about atmospheric Ambient pressure in several steps, each to a predetermined Temperature up to the final temperature between 400 ° C and 600 ° C heated and while maintaining the final temperature in one Atmosphere of a mixture of a carrier gas and chalcogen vapor are converted into semiconducting layers.

On The way can be good semiconducting layers at heating rates be obtained well below 10 ° C / second.

To The prior art must be ensured that when reaching the final temperature enough chalcogenes available are, so as complete as possible conversion the metallic precursor layers take place in semiconducting layers can.

This is ensured by an excess supply of chalcogens. Not consumed in the reaction, excess Chalcogen is combined with the carrier gas removed an exhaust duct of the furnace. According to the state of the art The chalcogens can and must be removed from the waste Chalcogen vapor / carrier gas mixture, also called exhaust gas, filtered out and disposed of as waste.

Furthermore, according to the prior art, the chalcogens for the thermal conversion of the metallic precursor layers are preferably provided via at least one layer of chalcogens on the metallic precursor layers, which then evaporate in the oven and are available to the process. A rapid and cost-effective coating process for chalcogens and a device suitable for carrying out the process has been described in the post-patent application PCT / EP 2008/062061 created.

at Only a part of the chalcogen condenses in this coating process on the substrates. The chalcogens that will not condense controlled discharged and disposed of as waste.

A Reprocessing for reuse is hardly possible. Therefore, the chalcogen vapor / carrier gas mixture should be as possible as needed fed to the process and losses during the Process should be avoided as much as possible.

Of the Invention is based on the object, a method and an apparatus for the thermal conversion of metallic precursor layers in semiconducting layers with the best possible quality and optimal use of the process gases, with the waste at Chalcogens of the entire process should be significantly reduced.

The The object underlying the invention is achieved by a method solved by forming an input and output side Gas lock for the oxygen-tight closure of a furnace chamber, introduction one or more with at least one metallic precursor layer prepared substrates into the furnace chamber, introducing a via the Width of the substrates as evenly as possible distributed chalcogen vapor / carrier gas mixture above the substrates at a pressure near atmospheric pressure, heating the substrates in the chalcogen vapor / carrier gas atmosphere to a final temperature with conversion of the metallic precursor layers in semiconducting layers, not dissipating in the reaction consumed chalcogen vapor / carrier gas mixture, cooling the substrates and running the substrates from the oven chamber.

By the invention reduces the amount of waste as the process gases be optimally exploited and there losses of process gases almost be avoided. This leads to a simplified production process and for the redaction of the costs, since also primarily less Chalkogene be used.

A further improvement of the method according to the invention is achieved when the substrates are in a protective gas atmosphere be heated to a temperature as possible no evaporation of chalcogens takes place.

Farther can be over the surface of the substrates between the gas locks a flow of the chalcogen vapor / carrier gas mixture be produced, whereby on the one hand the quality of the produced Semiconducting layers is improved. On the other hand, it can the amount of chalcogen vapor / carrier gas mixture to be supplied reduced compared to a static atmosphere become.

The Chalcogen vapor / carrier gas mixture is preferably by carrier gas, which flows past molten chalcogens and chalcogen vapor absorbs, generates.

Preferably becomes the chalcogen selenium and as a protective / carrier gas inert gas, such as nitrogen.

To the conversion of the metallic precursor layers into semiconducting Layers and before removing the not consumed in the reaction Chalcogen vapor may be the substrate in the chalcogen vapor / carrier gas atmosphere held at a predetermined temperature and then be cooled.

In In a further development of the invention, the substrates are in one furnace segmented into several temperature ranges in several steps heated to a respective predetermined temperature.

there For example, the substrates in the oven will be simultaneously and incrementally transported from segment to segment, whereby the given residence time is identical in the individual segments.

The Dwell time can be 60 seconds, for example.

The heating of the substrates can be carried out in stages from room temperature to, for example, about 150 ° C, 450 ° C and 550 ° C, with the end temperature not exceeding the 550 ° C mark must become.

The Substrate can then be in at least one Step to be cooled to room temperature.

For the provision of the necessary chalcogen vapor for conversion of the metallic precursor layers in semiconducting layers, the Substrates prior to introduction into the oven already with at least a Chalkogenschicht be provided. The chalcogens on the substrate then evaporate completely in the oven for thin layers stand in the oven in addition to the direct supply of the Chalcogen vapor / carrier gas mixture for the conversion process to disposal.

at Thick chalcogen layers can only be part of the chalcogens evaporate and the metallic precursor layers can partly directly with molten chalcogens in semiconducting Layers are converted.

The Chalcogen layers are preferred by vapor deposition of chalcogens applied to the metallic precursor layers. This can be done under atmospheric conditions in a continuous process.

The Invention may further be characterized in that the metallic Precursor layers by sequential sputtering of copper / gallium and indium.

To For this purpose, for example, consisting of glass substrates are first provided by sputtering with a molybdenum layer, on then a second layer of copper / gallium from a compound Copper / gallium target and finally a third layer be sputtered from indium from an indium target under high vacuum. typically, the coating with molybdenum takes place in a first sputtering plant, the coating with copper / gallium and indium in a second Sputter.

The Task is further solved by a device that from an oven with a segmented into several temperature ranges Furnace chamber having an opening for introducing the substrates and an opening for discharging the substrates with the smallest possible Dimensions, with a gas lock at the opening for introducing the substrates, with a gas lock at the opening to the Application of the substrates, with a transport for flat substrates for gradual and simultaneous transport all located in the furnace chamber substrates for each next segment and with an exhaust duct for removing one Chalcogen vapor / carrier gas mixture consists, characterized that in a wall of the furnace chamber between the gas locks means for Generation of a flow of a chalcogen vapor / carrier gas mixture are arranged along the substrates.

The Means for generating the flow consist of at least an opening in a wall of the oven chamber for feeding a chalcogen vapor / carrier gas mixture and at least an opening in the wall of the furnace chamber for suction of the chalcogen vapor / carrier gas mixture.

The Dimensions of the openings should be close to that of these substrates to be slush correspond, at least that the Height of the openings only insignificantly larger As the thickness of the substrates is, this can cause losses significantly reduced in process gases in connection with the gas locks become.

at such a device according to the invention in the furnace chamber, an internal pressure near atmospheric pressure a, due to the dimensions of the openings for passing through the substrates, as well as the associated gas curtains, the amount of gases supplied, the extraction of the gases or the chalcogen vapor / carrier gas mixture and the temperature. Of the Exact pressure can be over there ratio Adjust the supplied and extracted gases.

In an embodiment of the invention is the opening for supplying the chalcogen vapor / carrier gas mixture in the wall of the furnace chamber, that of the coated area a located in the furnace chamber substrate is opposite.

Preferably the chalcogen selenium is used.

The Temperatures in different segments can be, for example independent with the help of heating and cooling systems be adjusted from each other.

In A further development of the invention is each segment of the thermally isolated from other segments. This makes possible, that adjacent segments at significantly different temperatures can be brought.

Farther Each segment can be insulated thermally be to use the energy for heating the segment to reduce.

In an embodiment of the invention consist of the walls the furnace chamber made of graphite.

by virtue of the stepwise and simultaneous transport of the substrates of Segment by segment, is the residence time of the substrates in the individual Segments identical and can be, for example, about 60 seconds.

Several Segments at the beginning of the furnace chamber form a warm-up zone and a plurality of segments at the end of the furnace chamber form a cooling zone. The segments between warm-up zone and cooling zone is the zone where the thermal conversion takes place, the reaction zone.

The Warm-up zone is connected to the input-side gas lock on Entrance of the warming up provided. At the exit of the warm-up zone There may be an additional gas lock.

The Disconnect the gas locks at the beginning and at the end of the warm-up zone the atmosphere of the warming up zone from the atmosphere outside the oven chamber and from the atmosphere the reaction zone. This can be done in a protective gas atmosphere, especially with the exclusion of oxygen but also in the absence of chalcogen vapor, a warming of the substrates to one given temperature take place.

In An embodiment of the invention is the opening for supplying the chalcogen vapor / carrier gas mixture directly after the gas lock at the exit of the warm-up zone appropriate.

This has the advantage that the substrates in the warm-up zone in the absence of oxygen but also of chalcogen vapor to one Temperature, if possible, no condensation of chalcogen vapor can take place, be heated. Become the substrates then passed through the gas lock at the exit of the warming up is passed through the opening for supplying the chalcogen vapor / carrier gas mixture Chalcogen vapor for the entire surface of the substrates offered.

The Cooling zone is with the output side gas lock on End of the cooling zone provided. At the entrance of the cooling zone There may be an additional gas lock.

The Disconnect the gas locks at the beginning and at the end of the cooling zone the atmosphere of the cooling zone from the atmosphere outside the oven chamber and from the atmosphere the reaction zone. This can be done in a protective gas atmosphere, especially with the exclusion of oxygen, a cooling of the Substrates take place.

Farther prevent the additional gas locks at the end of the warm-up zone and at the beginning of the cooling zone both the exit of chalcogen from the reaction zone into the environment as well as the penetration of for example, oxygen and hydrogen in the reaction zone.

To the better exclusion of, for example, oxygen or hydrogen from the furnace chamber, the furnace chamber can be from a housing with an opening for introducing the substrates and an opening be surrounded to dispense the substrates.

The Housing can, for example, a stainless steel cladding be.

Farther the housing can be a separate housing exhaust own and it can be a purge with a protective gas provided be.

In An embodiment of the invention has the housing a separate cooling system. This allows the radiated Dissipate heat of the furnace chamber.

Finally, an oxygen sensor and / or an H ₂ Se sensor may be mounted in the housing.

Of the Oxygen sensor allows the penetration of oxygen in the space between housing and furnace chamber determine.

The H ₂ Se sensor is used as a safety measure to detect any possible formation of hydrogen selenide in time and to warn the operator accordingly.

In a development of the device, the gas flows on both sides of the gas locks independently be set.

The Gas locks of the furnace chamber can from each at least two gas curtains. There may also be additional Exhausts between the gas curtains be present. Thereby is safely prevented, the process gases the oven chamber uncontrolled being able to leave.

Prefers is used as protective / carrier gas an inert gas, such as Nitrogen, used.

The opening for introducing the substrates, the opening for spreading the substrates and the gas locks allow the device in a continuous process, at a pressure near the atmospheric pressure and under defined residual gas conditions, in particular with exclusion of oxygen and hydrogen, to operate. Also this can prevent the uncontrolled loss of process gases.

The means of transport, the opening for introducing the substrates and the opening for Ausbrin conditions of the substrates allow introduction of the substrates into the furnace chamber, transporting the substrates through the furnace chamber and applying the substrates after the metallic precursor layers have been converted into semiconductive layers out of the furnace chamber.

The Device is arranged so that the chalcogen vapor / carrier gas mixture mainly over an area of in the furnace chamber located substrates flows.

to Feeding the chalcogen vapor / carrier gas mixture over the opening for supplying the chalcogen vapor / carrier gas mixture is this opening over one or more Lines connected to a vaporization chamber.

In a continuation of the invention is the opening for supplying the chalcogen vapor / carrier gas mixture a slot-shaped opening perpendicular to the Transport direction is aligned and extending over the entire substrate located in the furnace chamber extends. this has the advantage of a more even distribution of Chalcogen vapor in the oven chamber.

The Lines from the evaporation chamber to the slot-shaped opening can along the slot-shaped opening for supplying the chalcogen vapor / carrier gas mixture distributed end to an even distribution of the chalcogen vapor / carrier gas mixture over the to receive the entire opening.

In a further development of the invention, the lines which lead to a slot-shaped opening in the lower part of the lines the shape of the slot-shaped opening accept. This allows a nearly uniform Distribution of the chalcogen vapor / carrier gas mixture via the entire slot-shaped opening away.

Farther The pipes in the lower part can be followed with constrictions be provided by relaxation zones.

This causes the chalcogen vapor / carrier gas mixture which flows through these constrictions dammed up and thus compressed and then expanded again. This process is repeated. Thereby the chalcogen vapor / carrier gas mixture is distributed the desired length and allows a homogeneous distribution of the chacogenous vapor.

The Evaporation chamber is a chamber with at least one outlet to remove the chalcogen vapor / carrier gas mixture to which the cables connect. The evaporation chamber can have at least one additional input to the supply with solid chalcogen and an access for the feeder have a carrier gas.

The solid chalcogen melts in the heatable evaporation chamber and forms a Chalkogensee. For dossing the chalcogens, the evaporation chamber be equipped with a level sensor.

The Carrier gas, which enters the evaporation chamber and preferably previously heated, takes in the evaporation chamber chalcogen vapor and the chalcogen vapor / carrier gas mixture is over one or more lines of the opening for feeding fed to the chalcogen vapor / carrier gas mixture.

Around the flow rate with the carrier gas to control the evaporation chamber flows through it monitors a flow meter and over Fine regulating valve can be adjusted. It is understood that the Control can run automatically.

Around a return flow from the opening to the feeder of the chalcogen vapor / carrier gas mixture to the vaporization chamber can prevent an additional carrier gas feed in each line between the evaporation chamber and opening for delivery be provided. The so-called process additive gas, which by these additional feeds is introduced generated doing a suction, the chalcogen vapor / carrier gas mixture the evaporation chamber sucks.

Around the flow rate at which the process additive gas in a line between the evaporation chamber and the opening for supplying the chalcogen vapor / carrier gas mixture flows, can control each line with a flow meter and adjusted via a fine regulating valve.

A increased flow rate of the process additive gas leads to a larger chalcogen vapor / carrier gas flow in the associated line between the evaporation chamber and slit-shaped opening for feeding of the chalcogen vapor / carrier gas mixture.

With the independent regulation of process additive gas flows can the homogeneity of the chalcogen vapor / carrier gas mixture be further improved perpendicular to the transport direction.

Since, as already described, not the entire chalcogen vapor is used up in the reaction, this chalcogen vapor / carrier gas mixture has to be removed as exhaust gas via the exhaust gas channel be led. To limit the loss of chalcogen, this offgas can be split by a flow divider. One part is then further discharged as exhaust gas, called residual exhaust gas, the other part can be made available to the process again, for example via the additional carrier gas feeds or via the carrier gas feed of the evaporation chamber. The temperature of the recirculated chalcogen vapor / carrier gas mixture should never fall below the condensation temperature of the chalcogen to avoid condensation of the chalcogen in the recirculation.

The Residual exhaust gas can be filtered and then removed. Of the Waste of chalcogens must be disposed of or reprocessed be supplied.

In a continuation of this exhaust gas recirculation Chalkogen is withdrawn from the residual exhaust gas and again the coating recycled gas enriched with chalcogen.

to Feeding the solid chalcogen into the evaporation chamber can at least one feeding device in the device to be built in. A feeding device may consist of a Container which can be funnel-shaped and which provides a supply of chalcogen, a metering device that it allows a given amount over at least one Piping into an evaporation chamber, and a valve exist for each pipeline. The valves are during open and stay open to the feed of the chalcogen otherwise closed, so that as far as possible an escape of chalcogen vapor from the evaporation chamber into the feed device is prevented in it.

at large facilities can have multiple entrances to supply with solid chalcogen a uniform Distribution can be ensured in an evaporation chamber. In this case, a feed device fixed Chalkogen evenly on the different inputs distribute the vaporization chamber, or it may also be for Each input may be provided with a separate supply device.

One further preventing leakage of chalcogen vapor from the Evaporation chamber in a feeder can by a Carrier gas feed into the pipeline between valve and evaporation chamber can be realized. The flow velocity This carrier gas feed can, for example, over detected a flow meter and adjusted via a fine regulating become.

In An embodiment of the invention are components that with the Chalcogen vapor or the chalcogen vapor / carrier gas mixture can be contacted preferably from a relative to this Mixture resistant material, such as graphite.

Farther Components that come in contact with chalcogen vapor should be heated so that condensation of the chalcogen on these components is prevented. This prevents a complicated cleaning and maintenance.

A Possibility to realize this, parts of the device in a block, for example made of graphite, accommodate and this with an integrated heater to the desired temperature too heat.

In A further development of the invention is the openings for supplying the chalcogen vapor / carrier gas mixture in a vapor deposition head, which is in a recess in the transport opposite wall is used, housed.

Of the Evaporation head is preferably made of a material which is resistant against the chalcogen vapor is, in particular, for example Graphite.

Of the Evaporator head can, for example, via an integrated heating, be brought to a desired temperature.

Farther can be a thermal decoupling of the evaporation head of the furnace chamber be provided. This allows the Aufdampfkopf in another Temperature as the temperature of the corresponding segment of the furnace chamber to keep.

In a further development of the invention, the vapor deposition head under a sealed hood with integrated cooling system provided become. The interior of the hood can be in a special design with a protective gas are flooded and sucked off.

In a continuation of the invention are further components come into contact with chalcogen vapor, for example, the evaporation chambers and the lines between the evaporation chamber and the opening for feeding the chalcogen vapor / carrier gas mixture, As well as nitrogen gas feeds housed in the Aufdampfkopf. The Accommodating the nitrogen gas feeds in the evaporation head has the advantage that already nitrogen gas in the evaporation head heated.

One Embodiment of the invention will be described with reference to the attached Drawings explained. It shows:

1 a schematic drawing of a furnace chamber for the thermal conversion of metallic precursor layers into semiconducting layers,

2 an evaporation head and

3 a schematic drawing of a selenium feed device.

1 shows a furnace chamber 1 with walls of graphite, which is surrounded by a, not shown, coolable stainless steel cladding. The space between the oven chamber and the stainless steel casing can be sucked off by suction and purged with nitrogen. The furnace chamber is divided into segments S1 ... S7.

In each segment S1 ... S7, a selected temperature can be controlled by a heating 2 or cooling system 3 be specified. The segments S1 ... S5 each have a heating system 2 and the segments S6, S7, each with a cooling system 3 fitted.

The warming-up zone S1 and the cooling-down zone S7 are provided with input and output gas locks 4.1 . 4.2 ; 4.3 . 4.4 fitted. Nitrogen is used as the protective or carrier gas. The gas locks 4.1 . 4.2 ; 4.3 . 4.4 are of the shape that the gas flows on both sides of the gas locks 4.1 . 4.2 ; 4.3 . 4.4 are independently adjustable.

The gas locks 4.1 . 4.2 ; 4.3 . 4.4 each consist of two gas curtains. Continue to have the gas locks 4.1 . 4.2 ; 4.3 . 4.4 one suction each between the two gas curtains.

Through the gas locks 4.1 . 4.2 ; 4.3 . 4.4 is possible, substrates 6 by means of a means of transport 5 through the individual segments S1 ... S7 of the furnace chamber 1 in the continuous process, at atmospheric pressure and under defined residual gas conditions, in particular with the exclusion of oxygen and hydrogen to transport.

The means of transport 5 , which is not specified in the drawing, consists of rotatably mounted graphite rolls on which the substrates 6 step by step from segment to segment along the furnace chamber 1 be pushed. These sliding and rotatable and provided with transport lugs push rods are provided.

To transport all substrates 6 to carry out simultaneously, the transport lugs before each Transporthub with the substrates 6 engaged by turning the push rod upwards and all substrates 6 simultaneously accelerated. At the end of each transport stroke, the braking of the substrates takes place 6 , Whose leading edge with the transport lug of the respective preceding substrate 6 engages. After the transport stroke the transport lugs are swung away again, whereupon the transport rod is moved back to the starting position.

The residence time of the substrates 6 in the individual segments S1 ... S7 is identical in each case and amounts to 60 seconds, although other times can also be set.

In the method, a layer stack of molybdenum on a glass substrate 6 , a copper / gallium and indium layer 7 and a thin selenium layer 8th introduced into the segment S1. The molybdenum, copper / gallium and indium layers are deposited by sputtering in a vacuum chamber, whereas the selenium layer is evaporated at atmospheric pressure.

The gas locks 4.1 . 4.2 ; 4.3 . 4.4 and the heater 2 ensure in S1 a first warm-up of the substrate 6 to about 150 ° C in the absence of, for example, oxygen and hydrogen.

To 60 Seconds becomes the substrate 6 through the second gas lock 4.2 transported through in the second segment S2, in which the substrate 6 warmed to about 450 ° C.

According to the invention, selenium vapor in S2 is via a source of selenium immediately after the gas lock 4.1 . 4.2 fed to the process. For this purpose, a recess in the wall of the furnace chamber opposite the transport means is provided in S2. In this recess is a Aufdampfkopf 9 who in 2 is shown in detail, used. About the vaporization head and the opening therein 10.1 becomes a selenium vapor / nitrogen gas mixture 10 in the oven chamber 1 brought in.

Furthermore, the selenium begins on the substrates 6 in S2 to melt and then evaporates completely. The now vaporous selenium mixes with the Selendampf- / nitrogen gas mixture 10 the source and the nitrogen gas of the gas locks 4.1 . 4.2 ; 4.3 . 4.4 in the open chamber 1 to a Selendampf- / nitrogen gas mixture 10 , This gas mixture is controlled by controlling the gas flows through the furnace chamber 1 through the substrates therein to an exhaust passage 11 in the means of transport 5 opposite wall 1.1 the oven chamber 1 transported.

The gas flow is controlled so that upon reaching the final temperature in the third segment S3 at which the reaction takes place, while maintaining the temperature in S4 and a cooling in S5 genü There is only seldom steam and at least in sections S3. and S4 over the entire surface of the substrates 6 flows. Selenium not consumed in the reaction is via the exhaust channel 11 the oven chamber 1 transported between S5 and S6.

In the subsequent segments S6 and S7, the substrate becomes 6 cooled to about 250 ° C and 50 ° C and then from the oven chamber 1 discharged again.

The control of the gas flow is made possible by the gas flows on both sides of the gas lock 4.1 . 4.2 ; 4.3 . 4.4 and in the exhaust duct 11 are independently adjustable. The speed of the gas flow in the furnace chamber 1 from segment S2 to the exhaust duct 11 must be aware of the transport speed of the substrates 6 be coordinated.

The conversion of the precursor layers into semiconducting CIGS layers ( 12 ), already takes place in S3 at a temperature of about 550 ° C. Thereafter, the temperature of the substrate 6 held in S4 at about 500 ° C and cooled in S5 to about 350 ° C. As the exhaust duct 11 is between the segments S5 and S6, this cooling takes place in an atmosphere containing selenium instead. By the vapor pressure of the selenium in Selendampf- / carrier gas mixture 10 Re-evaporation of selenium is prevented during this cooling. This enables production of semiconductive layers of good quality. In particular, solar modules with good efficiencies can be produced from this.

For further protection, so that no selenium can escape into the environment, is the Aufdampfkopf 9 under a tight hood 13 provided with an integrated cooling system. The space between hood 13 and the evaporation head 9 can be flooded with nitrogen, or rinsed and sucked off.

In 2 is the vapor deposition head 9 shown in detail. The selenium vapor / nitrogen gas mixture 10 gets over a slit-shaped opening 14 in the evaporation head 9 perpendicular to the transport direction of the substrates 6 is aligned, in the oven chamber 1 brought in.

In order to obtain a uniform supply of selenium perpendicular to the transport direction, the selenium vapor must over the entire width of the substrates 6 evenly into the oven chamber 1 be introduced.

This has a line 15 via the selenium vapor / carrier gas mixture 10 in the lower part the shape of a slit-shaped opening 14 , This will be over the slot 15 for supplying the Selendampf- / carrier gas mixture 110 with several constrictions in the evaporation head 9 realized. The slot 15 for feeding runs parallel to the slot-shaped opening 14 and ends at this opening. The mixture accumulates and can then expand again in a relaxation zone. This process is repeated several times. As a result, the selenium vapor / carrier gas mixture is distributed 10 on the entire slot-shaped opening away.

3 shows a schematic drawing of a selenium feed device.

Selenium is commercially available spherically in solid state. The balls have a typical diameter of 3-5 mm. The selenkugeln are placed in a funnel-shaped container 16 poured. The funnel has at its lower end an opening through which the selenkalls can fall vertically downwards. In addition, the funnel is equipped with a level gauge.

The balls fall into a metering device 17 , The dosing device 17 consists of a cylindrical housing and a centrally rotatably mounted, also cylindrical rotary member, hereinafter referred to as drum. The housing has two holes, one on the top and one on the bottom on the same pitch diameter and offset in their position by 180 °. The inner rotary part has four holes, which lie on the same pitch circle diameter. In their length, the two parts are designed so that no selenium ball fits between them.

Lie the holes of the parts aligned over each other, can the selenium balls fall into the drum. If the drum is rotated by 90 ° the selenium balls can move the drum and the casing, vertically falling down, left.

about the amount of time that passes between the 90 ° turns and the number of selenium balls entering the bore of the drum you can adjust the number of selenium balls and thus dose the amount of selenium provided.

Then the selenium balls fall through a vertical pipeline 18 in a heated chamber 19 , also called evaporation chamber. In the vertical pipeline 18 is a, designed as a ball valve with full opening, valve 20 installed, which is opened only during the period of dosing. As a result, virtually no vapor can escape from the heated chamber, in which selenium vapor is present, into the supply device.

Further preventing the escape of selenium vapor from the vaporization chamber 19 in the feeder is by a stick material gas feed into the pipeline 21 between valve 20 and evaporation chamber 19 realized. This flow of nitrogen creates a flow into the vaporization chamber 19 into it and prevents a flow in the opposite direction.

As described, the selenium balls fall from above into a chamber 19 , The chamber 19 is a simple horizontal hole in a block of graphite, the vapor deposition head 9 in 2 , and is closed at both ends. In this chamber 19 , which in addition to Selenzuführung an input 22 and an exit 23 possesses, selenium collects. The mentioned accesses are located on the upper side of the bore.

The block is heated together with the selenium via a heater. By heating, the selenium is first melted and then evaporates at a further temperature rise. In the lower half of the chamber is then a liquid Selensee 24 , in the upper half Selendampf 25 ,

To the level in the chamber 19 To regulate, an unillustrated level sensor is provided. The level sensor gives a signal to the described metering device if there are too few selenium in the chamber 19 is. Thereupon, the process described begins with selenium in the chamber 19 falls. If a sufficient level is reached, the level sensor stops the dosing process via a signal.

The Selendampf, which is in the chamber 19 has formed, must now contact the substrates 6 continue to be conducted. It must be ensured that the selenium vapor can not cool down and condense. The transport of the vapor takes place via a carrier gas. Nitrogen is used as the carrier gas. This must first be at the same temperature as in the chamber 19 prevails, be heated. The nitrogen passes through the entrance 22 in the chamber 19 in which the selenium vapor is located. There it picks up the selenium and carries it through the exit 23 the chamber towards the substrate 6 , The administration 23 between the chamber 19 and slit-shaped opening 14 / 15 The feed must also be heated to prevent condensation of selenium, which would require extensive maintenance.

To this preheating the nitrogen gas, heating the evaporation chamber 19 and to make the transport routes easier, everything is in the evaporator head 9 housed in graphite. The whole steam head 9 is heated. The nitrogen gas is passed through a meander, not shown, in the vapor deposition head 9 carried out. The gas heats up to the temperature of the vapor deposition head 9 ,

In addition, the flow of the selenium vapor mixed nitrogen gas over another, in the line between the evaporation chamber 19 and slot-like opening to the feeder 21 located nitrogen gas feed 26 controlled. The inflow of this gas, called process additive gas, a slight suction is developed, which pulls the gas mixture from the chamber. The flow through the nitrogen gas feed for the process additive gas can be measured via a flow meter and adjusted via a fine adjustment valve.

To the flow rate of the nitrogen feed for the process additive gas 26 , the nitrogen feed into the pipeline 21 and the nitrogen feed into the vaporization chamber 22 These are each equipped with a flow meter and a fine regulating valve. This allows the corresponding rivers to be measured and then adjusted.

1

furnace chamber

1.1

wall

1.2

wall

1.3

Opening / input

1.4

Opening / output

2

heating system

3

cooling system

4.1

gas lock

4.2

gas lock

4.3

gas lock

4.4

gas lock

5

Mode of Transport

6

molybdenum on glass substrate

7

Metallic precursor layers

8th

Se layer

9

Aufdampfkopf

10

Selendampf- / nitrogen gas mixture

10.1

opening

11

exhaust duct

12

CIGS layer

13

Hood

14

Slot-shaped opening to the feeder

15

slot to the feeder

16

container

17

metering

18

pipeline

19

chamber

20

Valve

21

Nitrogen gas feed into the pipeline

22

entrance

23

output

24

Selensee

25

selenium vapor

26

Nitrogen gas feed for the process additive gas

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 0318315 A2 [0006]
• EP 0662247 B1 [0007]
• - EP 2008/007466 [0008]
• - EP 2008/062061 [0013]

Claims (20)

Process for the thermal conversion of metallic precursor layers on flat substrates into semiconductive layers in a furnace chamber, characterized by - forming an inlet and outlet gas lock ( 4.1 . 4.2 . 4.3 . 4.4 ) for the oxygen-tight closure of the furnace chamber ( 1 ), - introducing one or more substrates prepared with at least one metallic precursor layer ( 6 ) in the oven chamber ( 1 ), - introducing an across the width of the substrates ( 6 ) as evenly distributed chalcogen vapor / carrier gas mixture ( 10 ) above the substrates, - heating of the substrates ( 6 ) in the chalcogen vapor / carrier gas atmosphere ( 10 ) to a final temperature and conversion of the metallic precursor layers into semiconductive layers, - removal of the non-consumed in the reaction chalcogen vapor / carrier gas mixture ( 10 ), - cooling the substrates ( 6 ), and - removal of the substrates ( 6 ) from the furnace chamber ( 10 ). Method according to claim 1, characterized in that the substrates ( 6 ) are heated in a protective gas atmosphere to a temperature at which, if possible, no evaporation of chalcogens takes place. Method according to claims 1 and 2, characterized in that above the surface of the substrates ( 6 ) between the gas locks ( 4.1 . 4.2 . 4.3 . 4.4 ) a flow of the chalcogen vapor / carrier gas mixture ( 10 ) is produced. Process according to Claims 1 and 3, characterized in that the chalcogen vapor / carrier gas mixture ( 10 ) is generated by overflow of molten chalcogens with carrier gas. Method according to one of claims 1 to 4, characterized in that the substrates ( 6 ), after the conversion of the metallic precursor layers into semiconductive layers and before the removal of the chalcogen vapor not consumed in the reaction, in the chalcogen vapor / carrier gas atmosphere ( 10 ) are kept at a predetermined temperature and then cooled. Method according to one of the preceding claims, characterized in that the substrates ( 6 ) in a furnace chamber segmented into a plurality of temperature regions ( 1 ) are heated in several steps to a respective predetermined temperature. A method according to claim 6, characterized in that in the furnace chamber ( 1 ) ( 6 ) are transported simultaneously and step by step from segment to segment. Method according to one of the preceding claims, characterized in that the substrates ( 6 ) In the inert gas atmosphere to a temperature of about 150 ° C and then in the chalcogen vapor / carrier gas atmosphere to first about 450 ° C and then to the final temperature of about 550 ° C are heated. Method according to one of the preceding claims, characterized in that the substrates ( 6 ) before introduction into the oven chamber ( 1 ) are provided with at least one chalcogen layer. Method according to one of the preceding claims, characterized in that the metallic precursor layers on the substrate ( 6 ) are prepared by sequentially sputtering copper / gallium and indium onto a molybdenum coated flat glass substrate. Apparatus comprising a furnace having a furnace chamber segmented into a plurality of temperature regions, having openings for introducing and removing the substrates, with gas locks at the openings for introducing and removing the substrates, with a transport means for flat substrates for the stepwise and simultaneous transport of all in the furnace chamber located substrates to each next segment and with an exhaust passage for removing a chalcogen vapor / carrier gas mixture, characterized in that the openings ( 1.3 . 1.4 ) for loading and unloading the substrates ( 6 ) have the smallest possible dimensions that in a wall ( 1.1 ) of the furnace chamber ( 1 ) between the gas locks ( 4 ) Means for generating a flow of a chalcogen vapor / carrier gas mixture ( 10 ) longitudinally over the substrates ( 6 ) are arranged. Apparatus according to claim 11, characterized in that the means for generating a flow along the substrates ( 6 ) in or against the transport direction of openings ( 10.1 ) in a wall of the furnace chamber ( 1.1 ) for supplying or removing a chalcogen vapor / carrier gas mixture ( 10 ) or a carrier gas. Apparatus according to claim 12, characterized in that the opening ( 10.1 ) for supplying a chalcogen vapor / carrier gas mixture ( 10 ) Component of a vapor deposition head ( 9 ). Device according to claim 11 and 12, characterized in that the openings ( 10.1 . 11 ) to supply or lead the chalcogen vapor / carrier gas mixture, or the carrier gas, in the wall ( 1.1 ) of the furnace chamber ( 1 ), the be layered surface of one in the furnace chamber ( 1 ) substrate ( 6 ) is opposite. Device according to one of claims 11 to 14, characterized in that a warm-up zone at its output with a gas lock ( 4.2 ) is provided. Device according to claims 11 to 15, characterized in that the at least one opening ( 10.1 ) for feeding the chalcogen vapor / carrier gas mixture ( 10 ) directly after the gas lock ( 4.2 ) is attached. Apparatus according to claim 16, characterized in that the at least one opening ( 10.1 ) for feeding the chalcogen vapor / carrier gas mixture ( 10 ) is a slot-shaped opening which is aligned perpendicular to the transport direction and over the entire width of the in the furnace chamber ( 1 ) ( 6 ). Device according to one of claims 11 to 17, characterized in that the at least one opening ( 10.1 ) for feeding the chalcogen vapor / carrier gas mixture ( 10 ) via at least one line with an evaporation chamber ( 19 ) connected is. Device according to claim 18, characterized in that that leads to the slot-shaped opening lead, in the lower part of the shape of the slot-shaped opening and provided with constrictions followed by relaxation zones. Device according to one of claims 18 and 19, characterized in that the evaporation chamber ( 19 ) with at least one supply device for supplying the chalcogen vapor / carrier gas mixture, consisting of a container and a metering device, is connected via pipes with valves.