DE102008049281A1 - Diffusion device for solar cell production and process for the production of solar cells - Google Patents

Abstract

A diffusion device (1; 28) for solar cell production, comprising a first dopant source applicator (3) by means of which a dopant source can be arranged on a substrate (7), a first continuous furnace (hereinafter) arranged in the process direction (10) and traversable by the substrates (7) ( 12), by means of which dopant from the dopant source (5) in the substrate (7) diffused, in the process direction (10) after the first continuous furnace (12) arranged second continuous furnace (14; 44), which is adapted to a surface forming a passivating layer on the substrates (7) as they pass through the second continuous furnace (14; 44), and an etching device (16) disposed between the first (12) and second continuous furnaces (14; 44); during the passage of the first continuous furnace (12) at the Oberfgstens partially remove, and method for producing solar cells (60).

Description

The The invention relates to a diffusion device for solar cell production according to the preamble of claim 1 and a Process for the production of solar cells according to the The preamble of claim 14.

The Starting point for the industrial production of solar cells currently form usually solar cell substrates, which hereinafter referred to as substrates for short. As substrates For the most part, silicon wafers are used. Around Producing solar cells from substrates usually becomes a dopant diffused into the substrates. For this, the substrates are in heated to an oven, in the case of silicon, for example, to temperatures from a few hundred to over 1000 ° C. To this end The substrates are often batchwise in suitable Diffusion furnaces, for example tube diffusion furnaces, arranged and the diffusion using suitable process gases and temporal temperature sequences.

Around to achieve cost-efficient solar cell production largely automated production lines sought, which is often is referred to as inline production. In such a largely automated Line production can be described above, batchwise difficult to integrate operated diffusion furnaces. Recently, in the industrial production of solar cells therefore continuous ovens used. These can be very easy to integrate and enable in automated production lines the high throughput required in industrial production. Furthermore, the diffusion can be compared with those described above Tube furnaces are made in short diffusion times. The use However, this short diffusion times has the consequence that certain Doping profiles can not be practically produced. In particular, deeply driven emitters, the solar cells with high. Enabling efficiencies are the industrial manufacturing when using continuous ovens with short diffusion times inaccessible. The manufactured solar cells thus have a reduced efficiency compared to conventionally diffused Solar cells on.

Of the The invention is therefore based on the object, a diffusion device available when using continuous furnaces Efficiency improvement for the expense of low cost enabled by the solar cells.

These Task is solved by a diffusion device with the features of claim 1.

Farther the invention has the object, a method available by means of which using furnaces for The diffusion produced solar cells with increased efficiency can be.

These Task is solved by a method with the features of claim 14.

advantageous Further developments are each the subject of dependent claims.

The Diffusion device according to the invention for the solar cell fabrication has a first dopant source applicator on, by means of which a dopant source can be arranged on a substrate is, as well as a downstream arranged in the process of the substrates passable first continuous furnace, by means of which Dopant from the Dotierstoffquel le diffused into the substrate is. In the process direction is after the first continuous furnace, a second Continuous furnace arranged, which is adapted to a surface passivating layer to form on the substrates while these go through the second continuous furnace. Between the first and the Second continuous furnace is also an etching device arranged, which is adapted to layers, which during passing through the first continuous furnace at the surface the substrates have been formed to at least partially remove.

The at least partially removing these layers is required otherwise these are the formation of the surface passivating Can hinder layer in the second continuous furnace. The most common in industrial solar cell production used silicon substrates are, for example, during the diffusion in the first continuous furnace silicate glasses formed on the substrate surface, in particular phosphorus or borosilicate glasses which form a surface passivating Hinder layer on the substrates, they are not before entry removed in the second continuous furnace. The surface passivating Layer could in this case, for example, as a silicon oxide layer be executed.

By the passivation of the surfaces of the substrates becomes a near-surface recombination of generated charge carriers reduced. Will the diffusion device according to the invention used for emitter diffusion causes the passivation the surface of a so-called emitter passivation, which especially suitable for the reduction of recombination and thus proved to increase the efficiency of the manufactured solar cells Has.

Advantageously, there is also the possibility of dopant which has been diffused into the substrate in the first continuous furnace during the passage of the second continuous furnace to drive deeper into the substrate. From laboratory experiments it is known that such deeply driven emitters enable the production of solar cells with particularly high efficiencies. This is based on a more efficient collection of generated charge carriers. As a result, appropriately trained emitter profiles are often referred to as high power emitters. Especially when using such high-performance emitter, which already allow an increase in efficiency, the passivation of the surface of the substrates and the associated reduction of the charge carrier recombination has a particularly advantageous effect. The passivation of the substrate surfaces in the second continuous furnace in conjunction with a deeper driving of the dopant during the passage of the second continuous furnace thus allows a particularly large increase in efficiency and consequently an efficient utilization of the additional equipment.

As already mentioned, found in industrial solar cell production currently predominantly silicon substrates use. As dopants usually phosphorus or boron compounds are used. A preferred embodiment variant of the invention therefore provides that the etching device is arranged to be in the first Continuous furnace formed on the surface of the substrates At least partially remove phosphorus or borosilicate glass layers.

Around to form surface passivating layers on the substrates, It has proved to be advantageous in the interior of the second continuous furnace a Form process gas atmosphere. A further education of The invention therefore provides that in the second continuous furnace Such process gas atmosphere, preferably an oxygen atmosphere, can be formed is.

An advantageous embodiment of the diffusion device according to the invention provides a second dopant source applicator between the etching device and the second continuous furnace, by means of which at least one further dopant source can be arranged locally on the substrates. With such a second dopant source applicator further dopant sources can be applied to the substrates, which, for example, have a higher dopant content than the dopant source applied with the first dopant source applicator. The second continuous furnace is preferably designed in such a way that, during the passage through the second continuous furnace, dopant from the at least one further dopant source can diffuse into the substrate. As a result, during the passage of the second continuous furnace under the further dopant source, a particularly large amount of dopant is locally introduced into the substrate, so that there is a particularly strong local doping there. In this way, two-stage doping, in particular two-stage emitter or two-stage back surface fields, can be formed conveniently. Such two-stage doping have an advantageous effect on the efficiency of the manufactured solar cells and are described in more detail in the example German patent application with the file number 10 2008 017 467 ,

to Training a two-stage doping is not mandatory, that the heavy doping out of the further dopant source out he follows. In principle, it is also conceivable that the first dopant source has an increased content of dopant and this is applied only locally to the substrate. In return, the more dopant source to a lower dopant content and applied to the substrate at those locations which is not already provided a first dopant source. The result is again a two-stage doping, the heavily doped regions in this case being the first Go back dopant source. However, the preferred first dopant source have a lower dopant content and over the entire surface on one or more side surfaces the substrates are applied, as this is less demanding to the orientation of the substrates in the dopant source applicators provides.

In an advantageous embodiment variant of the invention, at least one continuous furnace to a transport system for the substrates, in which always remain substantially the same parts of the transport system inside the at least one continuous furnace. Such configured furnaces are known to be particularly energy efficient, since not continuously enter parts of the transport system with a relevant thermal mass in the heating zones of the continuous furnace, while leaving other hot parts of the transport system from the heating zone, as is the case for belt furnaces. Continuous furnaces with a transport system, in which substantially the same parts of the transport system remain inside the continuous furnace, therefore allow a more accurate and stable temperature control and a shortened design. The transport systems of the desired type also have the advantage that the risk of contamination entry is reduced in the continuous furnace, which can have a detrimental effect on the efficiency of the solar cell. As transport systems of the desired type are, for example, air cushion transport systems in question, which exemplifies in DE 198 57 142 A1 are described.

Since the gas inflows which are necessarily present in air-cushion transport systems in the continuous furnace, the process gas atmospheres can interfere with a preferred embodiment variant of the diffusion device according to the invention before transport systems, which are designed according to the Hubbalkenprinzip. Due to its low thermal mass, a lifting cord system is particularly preferably used. Continuous ovens with such a Hubschnursystem are commonly referred to as Hubschnuröfen. A detailed description of the Hubbalkenprinzips as well as the Hubschnursystems or Hubschnuröfen found for example in DE 100 59 777 A1 ,

by virtue of the described advantages of such transport systems, d. H. reduced Pollution input and efficient energy utilization as well as better Temperature controllability and stability, transport systems come according to the walking beam principle and above all lifting cord ovens increasingly used. Especially in these furnaces acts The invention is particularly advantageous. Because of the Walking beam principle is the length of such continuous furnaces limited. This is for the indiffusion of Dotierstoff no fundamental problem, because of the especially in the Hubschnuröfen reduced thermal Mass of the diffusion process can be done very quickly. A Such very fast processing is common referred to as rapid thermal processing or RTP for short. Indeed intensifies with this particularly fast processing the problem is that deep during the short diffusion times driven emitter can not be practically produced. To achieve a suitable emitter profile are therefore given the limited length at least two consecutively arranged Hubschnuröfen needed. Across from such a production line is the overhead of the invention Diffusion device, however, only in a comparative low-cost Ätzvor direction. A second Continuous furnace, however, is in the form of the second Hubschnurofens anyway available. The device according to the invention therefore makes possible the disadvantage of the limited diffusion time of a Hubschnurofens to turn into a considerable advantage, since with a small amount additional equipment required solar cells with a passivated high-performance emitter can be made. The production can also be in one Line production, d. H. the invention Device is in a so-called inline process readily integrated.

at an advantageous embodiment variant of the invention Device are the substrates the diffusion source applicators, Diffusion ovens and the etching device automatically by means of transport devices, preferably conveyor belts fed. This allows a fully automatic Litigation. In addition, the diffusion device is special preferably carried out continuously operable.

Solar cell production facilities with a diffusion device according to the invention benefit from the advantages of the invention. Such a solar cell manufacturing facility is preferably as automated assembly line production designed.

The inventive method for the preparation of Solar cells provides that a dopant source on a substrate is arranged, dopant from the dopant source in one first continuous furnace is diffused into the substrate while the diffusion of the dopant from the dopant source at a At least surface of the substrate formed layers be partially removed and passivated on the substrates a surfaces Layer is formed. The surface passivating Layer is doing after the at least partial removal of the formed on the surface of the sub strate layers formed in a second continuous furnace.

On this way, the recombination of generated charge carriers reduced in the manufactured solar cells and thus the efficiency be increased, the process easily in one Line production can be integrated.

advantageously, becomes an emitter or a backside field with the method a solar cell formed.

As As discussed above, currently silicon substrates are predominantly used used for the manufacture of solar cells, with phosphorus or boron can be used as dopants. A design variant The invention therefore provides that one during the diffusion the dopant from the dopant source at the surface formed of the substrate phosphorus or borosilicate glass layer at least partially removed. Otherwise, the Surface passivating layer its passivating effect not or only to a lesser extent unfold.

A preferred embodiment of the invention Procedure provides that in the first continuous furnace in the Substrate diffused dopant deeper in the second continuous furnace is driven into the substrate. This way, in addition to passivate the surface of the substrate a high power emitter be formed, which in turn an increase in efficiency causes. In cooperation with the surface passivation can in this way cost effective a strong increase in efficiency be achieved.

A development of the method according to the invention provides that after the at least part To remove the formed on the upper surface of the substrate layers at least one further dopant source is applied locally to the substrate, from which dopant is diffused into the substrate in the second continuous furnace. In this way, as already explained in connection with the device according to the invention, a two-stage doping can be realized. A particularly preferred embodiment variant of the invention therefore provides that a two-stage emitter or a two-stage rear field is formed. As already discussed above, this allows a more efficient collection of generated charge carriers as well as a further reduction of charge carrier recombination. For further details concerning two-stage doping or two-stage emitter or two-stage back side fields is the statements in the German patent application with the file number DE 10 2008 017 647 directed.

at A preferred embodiment variant of the invention are the Substrates in at least one continuous furnace, preferably in both continuous furnaces, transported by means of a transport system in which always essentially the same parts of the transport system inside the at least one continuous furnace remain. This brings up the top discussed benefits of efficient energy use, and one reduced risk of contamination entry, which is negative on the efficiency of solar cells produced, with itself. As already stated, such a transport system could work according to the walking beam principle.

One An example of this is the Hubschnursystem, which used in Hubschnuröfen and with which the substrates be transported particularly preferred. In conjunction with the Device according to the invention has already been stated that Such Hubschnursysteme have a low thermal mass and therefore are particularly suitable for RTP processes. The resulting very short diffusion times and the consequent that two Hubschnuröfen to form a suitable Emitter profiles are required to cause the inventive method particularly advantageous can be used in conjunction with lifting cord ovens, because in this case solar cells with increased efficiency can be produced with very little extra effort. In a particularly preferred embodiment variant of the invention Process, the substrates are therefore in at least one continuous furnace transported by means of a Hubschnursystems.

The Device according to the invention is to carry out the method according to the invention suitable. The inventive method as well as the invention Device become advantageous for the formation of an emitter or a back panel of a solar cell used. Especially Advantageously, the inventive Device as well as the inventive method for Production of solar cells with a two-stage emitter or a two-stage back panel can be used.

in the Below, the invention will be explained in more detail with reference to figures. As far as appropriate, are the same acting in it Elements provided with the same reference numerals. Show it:

1 A first embodiment of a device according to the invention in a schematic representation.

2 Schematic representation of a second embodiment of the invention, which is suitable for the formation of two-stage dopants.

3 Solar cell with a two-stage emitter and a two-stage back panel according to the prior art in a schematic representation.

4 Schematic representation of an embodiment of a method according to the invention.

1 shows a schematic representation of a first embodiment of a diffusion device according to the invention 1 for solar cell production. Herein is a first dopant source applicator 3 provided by means of which a dopant source 5 on a substrate 7 is sprayable. However, the first as well as all other Dotierstoffquellenapplikatoren can basically work on other mission principles, for example, the dopant source 5 rolled up or printed in a manner known per se.

In the process direction 10 Below is a first Hubschnurofen 12 provided in which the substrates by means of lifting cords 13a . 13b be transported. To each of the illustrated lifting cords 13a . 13b is usually provided another Hubschnur which is moved simultaneously to the associated Hubschnur. As a result, each results in a pair of Hubschnüren which is able to transport the substrates tipping stable. For better clarity, in the presentation of the 1 but only two lifting cords 13a . 13b reproduced, which are offset from each other to move.

As in the schematic representation of the first Hubschnurofens 12 is recognizable, always remain essentially the same parts of the lifting cords 13a . 13b formed transport system inside the continuous furnace 12 , Be true by the movement of the lifting cords short sections of the lifting cords 13a . 13b , which are temporarily inside the continuous furnace 12 are led out of this, or guided in the reversing movement in the continuous furnace. However, these sections are compared to the total length of the lift cords 13a . 13b short and affect the thermal conditions inside the continuous furnace only very slightly. In addition, they cause an impurity entry at best in the edge zones of Hubschnurofens 12 which continues to be low due to the shortness of the sections of the lift cords moving out of and / or into the lift cord furnace 13a . 13b ,

The substrates 7 be in the embodiment of 1 by means of a conveyor belt 24a automatically from the first dopant source applicator 3 the first lifting cord furnace 12 fed. At the exit they are from the lifting cords 13a . 13b to another conveyor belt 24b Pass them on to an etching device 16 supplies.

This etching device 16 is in 1 schematically represented by a container 17 with etching medium arranged therein 18 , For example, an etching solution. In the case shown, the substrates are in the etching medium 18 by means of an etching-medium-resistant conveyor belt 24c transported. From there you get to another conveyor belt 24d containing the etched substrates 7 the Hubschnurofen 14 supplies. The etching medium 18 is chosen such that the layers formed in the first Hubschnurofen on the substrate surface 11 be at least partially etched. These layers may be an exemplary use of silicon substrates 7 assuming phosphor or borosilicate glass layers 11 act during the diffusion process in the first Hubschnurofen 12 be formed. Simplified in the first Hubschnurofen 12 Therefore, some of the layers formed on the substrate surface are partially as glass layers 11 designated.

About the conveyor belt 24d the substrates reach lifting cords 15a . 15b , which in turn is representative of all lifting cords of the second continuous furnace 14 are shown. The sum of the lifting cords of the second continuous furnace 14 forms its transport system.

In the second lifting cord furnace 14 that is already in the first continuous furnace 12 from the dopant source 5 out in the substrate diffused dopant deeper into the substrate 7 driven. In addition, a surface passivating layer 21 on the substrate 7 educated. For this purpose, a process gas supply 20 provided, via which a process gas, such as oxygen, the second Hubschnurofen can be supplied, so that in the interior of a process gas atmosphere 22 can be trained. For example, when using silicon substrates and a process gas supply of oxygen, a silicon dioxide layer is formed as a passivating layer. In combination with the deeply driven dopant and the surface passivation, a passivated high-performance emitter can thus be formed. After leaving the second Hubschnurofens 14 becomes the substrate 7 the further manufacturing process by means of the conveyor belt 24e fed.

Apart from the Hubschnuröfen 12 . 14 are in the embodiment of 1 always conveyor belts provided as transport systems to realize an automated line production or an automatic production line. Instead of the conveyor belts obviously other transport systems known per se can be used.

2 illustrates a second embodiment of a diffusion device according to the invention in a schematic representation. The reproduced diffusion device 28 differs from the diffusion device 1 out 1 in that between the etching device 16 and a second lifting cord furnace 44 a second dopant source applicator 30 is provided, which the substrates of the etching device 16 out by means of the conveyor belt 24f be supplied.

By means of the second dopant source applicator 30 becomes another dopant source 35 sprayed onto the substrate. As in the case of the first dopant source applicator 3 explained, the further dopant source 35 alternatively be applied to the substrate in a manner known per se, for example by means of web-fed printing or other printing methods. The further dopant source 35 is preferably only locally on the substrate 7 applied and preferably has a higher dopant concentration than the dopant source 5 ,

In addition, the local with the other dopant source 35 provided substrates 7 over the conveyor belt 24f the second Hubschnurofen 44 performed, which in turn has lifting cords as a transport system, which schematically by the lifting cords 45a . 45b are shown, in turn, more lifting cords may be provided. In the second lifting cord furnace 44 is, as in the embodiment of the 1 , the dopant from the dopant source 5 deeper into the substrate 7 driven. Similar to the embodiment of 1 also becomes a surface passivating layer 21 educated. For this purpose, no separate process gas is supplied in the present case, but ver instead the atmospheric oxygen applies. Obviously, however, an additional process gas supply analogous to the process gas supply 20 from the embodiment of 1 and the resulting process gas atmosphere 22 be provided. In addition, in the second Hubschnurofen now dopant from the locally applied further Dotierstoffquelle 35 in the substrate 7 diffused and formed in this way a two-stage doping.

3 illustrates examples of two-stage doping based on a schematic representation of a solar cell 60 according to the prior art. This has a weakly doped emitter region 62 as well as a heavily doped emitter region 63 which together form a two-stage emitter. This two-stage emitter, which is also referred to as a selective emitter, could, for example, with the device 2 will be realized. These would be the other dopant sources 35 over the heavily doped emitter regions 63 to arrange, so by diffusion of the dopant during the passage of the second Hubschnurofens 44 the heavily doped emitter regions 63 be formed.

3 further illustrates a two-stage backside field formed from the lightly doped region 67 the back panel and the heavily doped areas 69 of the back side field. This two-stage rear side panel could be realized with a device according to the invention according to the embodiment of 2 , As 3 Illustrated, usually the metal contacts 65 the front or the metal contacts 71 the back over the respective heavily doped areas 63 . 69 arranged.

4 shows a schematic diagram of an embodiment of the method according to the invention. As can be seen, a dopant source is first arranged on a substrate 80 , Subsequently, dopant from the dopant source is diffused into the substrate in a first continuous furnace 82 ,

As already explained, during the diffusion in the first continuous furnace, layers are formed on the substrate surface, for example silicate glass layers, which hinder the formation of an active surface passivating layer. For this reason, these layers formed on the surface during the passage of the first continuous furnace are subsequently removed 84 ,

In the illustrated exemplary embodiment, further dopant sources are additionally arranged locally on the substrate to form a two-stage doping, for example a two-stage emitter 86 ,

Subsequently, in a second continuous furnace, as it were, simultaneously the dopant from the dopant source is driven deeper into the substrate 88 , Dopant from the other dopant sources diffused into the substrate 88 and also formed a surface passivating layer 88 ,

through such a method may for example be a solar cell produced with a selective and passivated high-performance emitter low cost become. Especially when using Hubschnuröfen as Continuous furnaces can be such a selective and passivated High-performance emitter are produced inexpensively. This can also be due to the short processing times possible at a high throughput and in a line production, which preferably as automatic assembly line production is executed.

1

Diffusion fuel facility

3

first Dotierstoffquellenapplikator

5

dopant

7

substratum

10

process direction

11

glass layer

12

first Hubschnurofen

13a

lift cord

13b

lift cord

14

second Hubschnurofen

15a

lift cord

15b

lift cord

16

etching

17

container

18

etching medium

20

Process gas supply

21

surfaces passivating layer

22

Process gas atmosphere

24a

conveyor belt

24b

conveyor belt

24c

conveyor belt

24d

conveyor belt

24e

conveyor belt

24f

conveyor belt

28

diffuser

30

second Dotierstoffquellenapplikator

35

Further dopant

44

second Hubschnurofen

45a

lift cord

45b

lift cord

60

solar cell

62

weak doped emitter region

63

strongly doped emitter region

65

metal contacts front

67

weak doped area of the back panel

69

strongly doped area of the back panel

71

metal contacts back

80

arrangement Dopant source on substrate

82

diffusing dopant

84

distance at the surface of formed layers

86

arrangement further dopant sources on substrate

88

dopant drive deeper / diffuse / form surfaces passivating layer

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

• - DE 102008017467 [0015]
• - DE 19857142 A1 [0017]
• - DE 10059777 A1 [0018]
• - DE 102008017647 [0027]

Claims (20)

Diffusion device ( 1 ; 28 ) for the production of solar cells, - a first dopant source applicator ( 3 ), by means of which a dopant source ( 5 ) on a substrate ( 7 ) can be arranged, - one in the process direction ( 10 ) arranged downstream of the substrates ( 7 ) passable first continuous furnace ( 12 ), by means of which dopant from the dopant source ( 5 ) in the substrate ( 7 ) is diffusible, characterized by - one in the process direction ( 10 ) after the first continuous furnace ( 12 ) arranged second continuous furnace ( 14 ; 44 ), which is adapted to a surface passivating layer ( 21 ) on the substrates ( 7 ) while forming the second continuous furnace ( 14 ; 44 ), and - one between the first ( 12 ) and the second continuous furnace ( 14 ; 44 ) arranged etching device ( 16 ), which is set up during the passage of the first continuous furnace ( 12 ) on the surface of the substrates ( 7 ) trained layers ( 11 ) at least partially remove. Diffusion device ( 1 ; 28 ) according to claim 1, characterized in that the etching device ( 16 ), is arranged in the first continuous furnace ( 12 ) on the surface of the substrates ( 7 ) formed phosphorus or borosilicate glass layers ( 11 ) at least partially remove. Diffusion device ( 1 ; 28 ) according to one of the preceding claims, characterized in that in the first continuous furnace ( 12 ) in the substrate ( 7 ) diffused dopant in the second continuous furnace ( 14 ; 44 ) deeper into the substrate ( 7 ) is recoverable. Diffusion device ( 1 ) according to one of the preceding claims, characterized by an inside of the second continuous furnace ( 14 ) formable process gas atmosphere ( 22 ), preferably an oxygen atmosphere. Diffusion device ( 28 ) according to one of the preceding claims, characterized in that between the etching device ( 16 ) and the second continuous furnace ( 44 ) a second dopant source applicator ( 30 ) is provided, by means of which at least one further dopant source ( 35 ) locally on the substrates ( 7 ) can be arranged. Diffusion device ( 1 ; 28 ) according to one of the preceding claims, characterized in that at least one continuous furnace ( 12 . 14 ; 44 ), preferably both continuous furnaces ( 12 . 14 ; 44 ), a transport system ( 13a . 13b . 15a . 15b ), in which always substantially the same parts of the transport system ( 13a . 13b . 15a . 15b ) in the interior of the at least one continuous furnace ( 12 . 14 ; 44 ) remain. Diffusion device ( 28 ) according to claim 7, characterized in that the transport system ( 13a . 13b . 15a . 15b ) is designed according to the Hubbalkenprinzip and preferably as Hubschnursystem ( 13a . 13b . 15a . 15b ) is executed. Diffusion device ( 1 ; 28 ) according to one of the preceding claims, characterized in that the substrates ( 7 ) the diffusion source applicators ( 3 ; 30 ), Diffusion furnaces ( 12 . 14 ; 44 ) and the etching device ( 16 ) automatically by means of transport devices ( 24a . 24b . 24c . 24d . 24e ; 24f ), preferably conveyor belts ( 24a . 24b . 24c . 24d . 24e ; 24f ), can be fed. Diffusion device ( 1 ; 28 ) according to one of the preceding claims, characterized in that it is continuously operable. Solar cell manufacturing device comprising a diffusion device ( 1 ; 28 ) according to any one of the preceding claims. Solar cell manufacturing device according to claim 11, characterized in that this as an automated assembly line production is designed. Use of a diffusion device ( 1 ; 28 ) according to one of claims 1 to 10 for the formation of an emitter ( 62 ) or a back panel ( 67 ) of a solar cell ( 60 ). Use of a diffusion device according to ( 28 ) according to one of claims 13 to 14, characterized in that by using a diffusion device ( 28 ) with the features of claim 6 or 7, a two-stage emitter ( 62 . 63 ) or a two-stage back field ( 67 . 69 ) is formed. Process for the production of solar cells ( 60 ), in which - a dopant source ( 5 ) on a substrate ( 7 ) is arranged ( 80 ); Dopant from the dopant source ( 5 ) in a first continuous furnace ( 12 ) in the substrate ( 7 ) is diffused ( 82 ); During the diffusion of the dopant from the dopant source ( 5 ) on a surface of the substrate ( 7 ) trained layers ( 11 ) are at least partially removed ( 84 ); - on the substrates ( 7 ) a surface passivating layer ( 21 ) is formed ( 88 ); characterized in that the surface passivating layer ( 21 ) after the at least partial removal of the the surface of the substrate ( 7 ) trained layers ( 11 ) in a second continuous furnace ( 14 ; 44 ) is formed ( 88 ). Method according to claim 14, characterized in that one during the diffusion ( 82 ) of the dopant from the dopant source ( 5 ) on the surface of the substrate ( 7 ) formed phosphorus or borosilicate glass layer ( 11 ) is at least partially removed ( 84 ). Method according to one of claims 14 to 15, characterized in that in the first continuous furnace ( 12 ) in the substrate ( 7 ) diffused dopant ( 82 ) in the second continuous furnace ( 14 ; 44 ) deeper into the substrate ( 7 ) ( 88 ). Method according to one of claims 14 to 16, characterized in that after the at least partial removal ( 84 ) at the surface of the substrate ( 7 ) trained layers ( 11 ) at least one further dopant source ( 35 ) locally on the substrate ( 7 ) is applied ( 86 ), from which in the second continuous furnace ( 14 ; 44 ) Dopant in the substrate ( 7 ) is diffused ( 88 ). Method according to claim 17, characterized in that a two-stage emitter ( 62 . 63 ) or a two-stage back field ( 67 . 69 ) is formed ( 86 . 88 ). Method according to one of claims 14 to 18, characterized in that in at least one continuous furnace ( 12 . 14 ; 44 ), preferably in both continuous furnaces ( 12 . 14 ; 44 ), the substrates ( 7 ) by means of a transport system ( 13a . 13b . 15a . 15b ), in which essentially the same parts of the transport system ( 13a . 13b . 15a . 15b ) in the interior of the at least one continuous furnace ( 12 . 14 ; 44 ) remain. Method according to claim 19, characterized in that the substrates ( 7 ) in the at least one pass ( 12 . 14 ; 44 ) are transported according to the Hubbalkenprinzip, preferably by means of a Hubschnursystems ( 13a . 13b . 15a . 15b ).