WO2020082282A1

WO2020082282A1 - Vapor deposition apparatus and use thereof

Info

Publication number: WO2020082282A1
Application number: PCT/CN2018/111780
Authority: WO
Inventors: Shou PENG; Xinjian Yin; Ganhua FU; Michael HARR; Bastian SIEPCHEN
Original assignee: China Triumph International Engineering Co., Ltd.; Ctf Solar Gmbh
Priority date: 2018-10-25
Filing date: 2018-10-25
Publication date: 2020-04-30

Abstract

An apparatus (1) for vapor deposition of a sublimated source material (22) as a thin film on a substrate (2) and the use thereof are provided. The apparatus comprises a vacuum chamber (10) and at least one separate crucible chamber (20) containing a crucible (21) and being located outside and on one side next to the vacuum chamber (10). The crucible chamber (20) and the vacuum chamber (10) are connected via a vapor distributor (30) for distributing the sublimated source material (22) in the crucible (21) of the crucible chamber (20) into the vacuum chamber (10). The vapor distributor (30) comprises a distributor heater (31) for heating the vapor distributor (30) and openings (32) for injecting the sublimated source material (22) onto the substrate (2). The vacuum chamber (10) comprises a transportation system (11) for supporting the substrate (2) and a substrate heater (12) for heating the substrate (2).

Description

An apparatus for vapor deposition of a sublimated source material as a thin film on a substrate

The invention relates to an apparatus for vapor deposition of a sublimated source material as a thin film on a substrate, and to the use of the apparatus for heating and depositing a compound selected from the group comprisingCdTe, CdTe: As, CdS, CdS _xTe _1-x, CdSe, CdSe _xTe _1- _x, ZnTe, Cd _xZn _1-xTe, MgTe, Mg _xZn _1-xTeand CuTe onto said substrate.

State-of-the-art

Closed Space Sublimation (CSS) method is a suitable technique for the deposition of high efficiency solar cells at high substrate temperature (600 to 900 K) and this technique has been adopted, for example, for depositionof CdS/CdTe layers for CdTe solar cells. Closed Space Sublimation (CSS) is a kind of thermal evaporation by nature and belongs to the physical vapor deposition technique. In prior art, the source and substrate in case of CdTe are kept at a close distance, for example 2 mm, whereas top and bottom heaters can be chosen according to the temperature needed to evaporate either at atmospheric pressure, wherein the process chamber is filled with a certain gas like argon (Ar) or nitrogen (N ₂) , or at lower pressures in the range of 10 ^-4 to 10 ^-1 mbar, i.e. 0.01 Pa to 10 Pa. There is a need of good temperature control. The important process parameters are hence the temperatures of the source material, for example evaporated from a crucible, andof the substrate, the nature of the atmosphere, the pressure in the process chamber, and the compositionof the source material. These parameters are inter-related. For example, the partialpressures of Cd and Te ₂ in the process chamberareimportant in determining the rate of deposition, and these pressures, or the dissociation pressure of CdTe, depend exponentially on temperature. The CSS is usually performed as a bottom-up process, wherein the substrate is moved above and across a crucible serving as evaporation source. In this way, the evaporated material is deposited on the underside of the substrate.

There are several disadvantages of such a CSS method:

a) It is difficult to decouple the crucible temperature from thesubstrate temperature. Since the crucible is very close to the substrate, the crucible temperature has great influence on the substrate temperature, which makes the control of substrate temperature more complicated since the filling level of crucible is changing during the production.

b) Since the crucible and the substrate are arranged in the same processing chamber, it is often necessary to open the whole apparatus for CSS when the crucible is empty or needs to be refilled. Thus, ambient pressure has to restored and afterwards the whole processing chamber has to be evacuated again. This is time-consuming.

c) In the bottom-up process, it is difficult tosupport the substrate to which the deposition takes place, because only edge sides can be supported to transport the substrate. If the substrate is supported in the middle, the effective active area will be decreased.

d) Further, in case a glass substrate is used, it is also difficult to heat the glass substrate to very high temperature. Since the glass substrate is hold only in side regions, it is very hard to heat the glass above 550℃. Such high temperatures near the transformation temperature of the glass cause big bending and sagging of the glass substrate. On the other hand, it is well known that the higher the glass temperature is, the better the CdTe modules perform.

Objective of the invention

It is therefore an object of the present invention to provide an apparatusfor the closed space sublimation method which reduces or prevents the above-mentioned disadvantages and which allows to easily control the temperatures of a crucible and of a substrate to be coated separately from each other.

Summary of the invention

The invention will be solved by an apparatus for vapor deposition of a sublimated source material as a thin film on a substrate according to the independent claim 1. Preferred embodiments are given in the dependent claims.

According to the invention, the apparatus comprises a vacuum chamber and at least one separate crucible chamber containing a crucible and being located outside and on one side next to the vacuum chamber, wherein said crucible chamber and said vacuum chamber are connected via a vapor distributor for distributing the sublimated source material of thecrucible of the crucible chamber into the vacuum chamber. Said vapor distributor comprises a distributor heater for heating the vapor distributor and openingsfor injecting the sublimated source material onto asubstrate. Said vacuum chamber comprises a transportation system for supporting said substrate and a substrate heater for heating said substrate. Due to this composition of the apparatus, atemperature of said crucible and a temperature of said substrate and a temperature of said vapor distributor are decoupled from each other. The transportation system is also suited for moving the substrate through the vacuum chamber.

According to the invention, the vacuum chamber is understood in particular to mean a chamber which has a rigid enclosure from which air and other gases are removed by a vacuum pump. This results in a low-pressure environment within the chamber, commonly referred to as a vacuum.

According to the invention, the crucible chamber is understood in particular to mean a chamber which contains a crucible. The crucible contains the source material which will be sublimated during the CSS process. The crucible chamber is located outside the vacuum chamber. This means that the crucible is situated not inside the vacuum chamber and next to the substrate but is completely separated from the substrate and hence the vacuum chamber. The crucible chamber is located on one side next to the vacuum chamber, which means that the crucible chamber with the crucible is located on the right or left side of the vacuum chamber but not above or below the vacuum chamber with the substrate to be coated.

As the vacuum chamber and the crucible chamber are separated from each other, but the vapor of the sublimated source material needs to be transported to the substrate to be covered, both chambers are connected via the vapor distributor for distributing the sublimated source material of the crucible from the crucible chamber into the vacuum chamber. The vapor distributor reaches into the vacuum chamber and extends over the whole width of the substrate. The width of the substrate is measured perpendicular to the transportation direction into which the substrate is moved through the vacuum chamber and parallel to the side of the substrate supported by the transportation system.

As the temperature regime of the CSS system is very critical, the vapor distributor as well as the vacuum chamber each comprise an own heater for heating the vapor distributor and the substrate within the vacuum chamber, respectively, to a suitable temperature. The vapor distributor has openingsfor injecting the sublimated source material into the vacuum chamber into the direction of the substrate. The openings are arranged in that part of the vapor distributor which extends over the substrateand may have different forms and sizes. For instance, the openings are slits with an opening width of 5 mm. The substrate heater is located near the substrate for heating the substrate in a laminar manner.

For solving the transportation problem of huge substrates, such as glass substrates, a transportation system comprising rollers or at least one beltis used. The substrate lays on the rollers or the at least one belt and passes the vapor distributor with the openings.

By separating the crucible chamber and the vacuum chamber with the substrate to be coated, the temperature of said crucible and the temperature of said substrate and the temperature of said vapor distributor are decoupled from each other, because each have its own heater, which is controlled by a temperature controller. In the result, the homogeneity of the deposited film may be improved. The inventive apparatus may be used in bottom-up CSS processes, where the sublimated material moves from the bottom to an underside of the substrate positioned above the vapor distributor, or in top-down CSS processes, where the sublimated material moves from the top to an upper side of the substrate positioned below the vapor distributor. The words “above” and “below” as well as “bottom” and “top” are used as commonly used.

In an embodiment of the inventive apparatus, the substrate is positioned underneath said vapor distributorand the substrate heater is positioned underneath said transportation system. According to the invention, something is underneath something else means that in case of the substrate heater, the substrate heater is located under the substrate in order to heat said substrate from its bottom side (underside) . In case of the substrate is underneath the vapor distributor, means that the substrate is positioned and transported in horizontal direction between the vapor distributor and the substrate heater, so that the substrate will be coated at its surface side (upper side) opposite to its bottom side (underside) . This arrangement results in a top-down deposition of the sublimated material and is advantageous since the substrate is supported on that surface side where the material is not deposited as a film. Furthermore, substrate materials which soften at high temperatures can be better supported and therefore higher substrate temperatures can be used during the deposition process resulting in better characteristics of the deposition process and of the deposited film.

In an embodiment of the inventive apparatus, the apparatus comprises two separate crucible chambers, both located outside said vacuum chamber. In a special embodiment, both crucible chambers are connected to one vapor distributor. However, it is also possible that each crucible chamber has its own vapor distributor. In a further special embodiment, a first crucible chamber is located on a left side of said vacuum chamber and a second crucible chamber is located one a right side of said vacuum chamber. According to the invention, the apparatus will be considered in a horizontal arrangement. Hence, the position of a first crucible chamber on a left side of said vacuum chamber is understood as the location illustrated exemplarily in Fig. 1 and a second crucible chamber is located one a right side of said vacuum chamber, hence on the opposite side of the vacuum chamber according to the first crucible chamber in the horizontal direction. However, in other embodiments, both crucible chambers may be arranged on the same side of the vacuum chamber.

One advantage of using two separate crucible chambers, each with a crucible inside the crucible chamber, is that different materials can be vaporized and hence different material compositions can be deposited on the substrate to be coated. For instance, it is easier to control the composition of the deposited layer by controlling separately the temperature of different crucibles. Another advantage of using crucibles pairwise is that a better layer homogeneity can be achieved, for instance by using two crucibles chambers vaporizing the same material. The last effect is particularly achieved when the two crucible chambers are located on both sides of the vacuum chamber as described above. Furthermore, the deposition rate may be increased. Hence, it is advantageous to arrangethe crucibles always in pairs. According to a specific embodiment, in one pair, one crucible is located on the left side of vacuum chamber and the other one is located on the right side of vacuum chamber.

Although in the last passages always two crucible chambers are mentioned, the inventive apparatus may comprise more than two. And even more than two crucible chambers may be connected to one and the same vapor distributor. Thus, films made of a material composition comprising more than two elements or compounds, each of them sublimated in an individual crucible chamber, may be formedon the substrate to be coated. The inventive apparatus provides the advantage that each element or compound may be heated in its individual crucible chamber to its own individual sublimation temperature. As explained above, it is possible to heat and control the crucibles separately from each other.

In case of more than two crucible chambers, in particular in case of different source materials sublimated in the individual crucible chambers, vapors of said different sublimated source materials are fed into the vapor distributor and are mixed before the vapors are injected via said openings of the vapor distributor onto the substrate, according to a specific embodiment. The mixing may take place before the vapors reach a portion of the vapor distributor located in the vacuum chamber or within the portion of the vapor distributor located in the vacuum chamber.

However, the sublimated materials may also mix after leaving the vapor distributor. In this case, the vapor distributor may have two or more separate distributor channels inside, wherein only the sublimated source material of one crucible chamber flows within an individual one of the distributor channels. The vapor distributor then has a plurality of openings, wherein each opening is connected to an individual one of the distributor channels. Advantageously, openings connected to distributor channels containing different sublimated source materials are arranged in an interdigitated manner such that a good mixing of the sublimated source materials is achieved before the sublimated source materials reach the substrate surface to be coated.

After reaching a certain temperature (the sublimation temperature of the source material) , the vapor of the sublimated source material is guided or transferred from the crucible chamber to the vacuum chamber via the vapor distributor. The vapor distributor is heated by the distributor heater to keep the sublimated source material at the certain temperature and prevents deposition of the sublimated source material within the vapor distributor. The vapor distributor may be directly heated. That means, the vapor distributor is made of a material, for instance metal or graphite, which can be heated by a current flowing through the material. In this case, the distributor heater is a device for providing a current to the vapor distributor. However, the vapor distributor may be heated also indirectly by heat transfer via conduction, convection or radiation. In this case, the distributor heater may be a heating element integrated in the wall of the vapor distributor or arranged on the outside of the wall of the vapor distributor or a heating lamp arrangement or any other kind of heater.

The source material vapor is injected onto the substrate via the openings of the vapor distributor. The vapor density and/or the vapor composition inside the vapor distributor may be analyzed by an analyzing unit, for instance a flow meter or a spectrometer, wherein the analyzing unit is at least partially arranged within the vapor distributor at any position between the crucible chamber and the openings of the vapor distributor. There may be also a plurality of analyzing units analyzing the change of vapor density and/or vapor composition along the length of the vapor distributor.

In a further embodiment of the inventive apparatus, crucible heaters are located around said crucible for heating said crucible inside the crucible chamber. The crucible heaters heat the crucible to a temperature which is needed for sublimating the source material in the crucible, so that the sublimated source material can be transported by the vapor distributor through the openings onto the substrate to be coated. Each crucible has its own crucible heaters that can be controlled separately. The crucible heaters may be arranged within the crucible chamber or in the wall of the crucible chamber or even outside the crucible chamber. Furthermore, although a plurality of crucible heaters is named, also only one crucible heater may be arranged for heating the crucible.

In a preferred embodiment of the inventive apparatus, the crucible chamber has a cover for refilling the crucible with sublimated source material. When the crucible is empty, the vacuum chamber maybe vented. Afterwards, the cover of the crucible is opened and the source is refilled. After refilling, the vacuum chamber may be pumped down for further processing. According to these proceedings, the whole vacuum chamber has to be vented resulting in a full stop of all deposition processes performed within this vacuum chamber. If, however, more than one crucible chamber containing the same source material is provided within the vacuum chamber at a specific range of position and the crucible in the other crucible chamber contains still enough source material, only the empty crucible chamber may be separated from the vacuum chamber and the other crucible chamber can cover the necessary deposition process. For this purpose and according to a special embodiment, a valve, a shutter or some other means for separating the crucible chamber from the vacuum chamber is arranged within the vapor distributor dividing the inside of the vapor distributor into two parts hermetically separated from each other. Thus, the deposition process has not to be interrupted in order to refill the empty crucible in this case. A specific range of position means that the crucible chambers correspond to the same layer to be deposited on the substrate. If, for instance, an apparatus comprises six crucible chambers, wherein each two of them are one pair providing the same sublimated source material, the first pair of crucible chambers deposits a first film of material A onto the substrate, the second pair of crucible chambers deposits a film of material B onto the first film of material A, and the third pair of crucible chambers deposits a second film of material A onto the film of material B. In this case, the first pair of crucible chambers and the second pair of crucible chambers do not lie in the same specific range of position, since they do not form the same film in the layer stack on the substrate. Therefore, a crucible chamber of the third pair may not cover for an empty crucible chamber of the first pair.

In an embodiment of the inventive apparatus, said vacuum chamber and said crucible chamber are connected to a vacuum system for generating a vacuum, especially a vacuum with a vacuum level of 10 ^-4 to 10 ^-1 mbar, i.e. 0.01 Pa to 10 Pa. Closed space sublimation (CSS) is one of the simplest methods in physical vapor deposition. Materials, especially semiconductors, that evaporate below 800℃ can be coated on substratesin both vacuum and atmospheric pressure. Researchers observed that the deposition rate of special materials increasesas the source temperature increases for a deposition under vacuum.

In a further embodiment of the inventive apparatus, a carrier gas source is provided which is suited for introducing a carrier gas into the crucible chamber. The carrier gas is used for carrying vapor of the sublimated source material via said vapor distributor to the substrate. A carrier gas is usually an inert gas such as helium or argon or an unreactive gas such as nitrogen. However, the carrier gas may also be a reactive gas like oxygen (O ₂) , selenium (Se ₂) or may contain such reactive species or other precursors of the material to be coated, and/or may contain dopants like arsenic. Using a carrier gas has the effect of improving the layer homogeneity.

In another further embodiment of the inventive apparatus, said substrate is of glass. Acommonly used substrate material for thin-film solar cells is a transparent substrate. However, any other kind of substrate can also be used in the inventive apparatus.

In an embodiment of the inventive apparatus, a distance between said vapor distributor and said substrate is in the range of 1 mm to 50 mm, preferably in the range of 1 mm to 20 mm. This distance is suitable, because too large distance will cause a low utilization of source materials.

In another embodiment of the inventive apparatus, the temperature of the substrate is in the range of room temperature to 800℃, preferably in the range of 400℃ to 700℃, and more preferably in the range of 500℃ to 620℃. In particular when using a glass substrate, the temperature of the substrate should not exceed 620℃.

In another further embodiment of the inventive apparatus, the temperature of the crucible is in the range of 200℃ to 1000℃, preferably in the range of 300℃ to800℃, and more preferably in the range of 600℃ to 700℃.

In an embodiment of the inventive apparatus, a temperature of the vapor distributor is in the range of 200℃ to 1000℃, preferably in the range of 300℃ to800℃, and more preferably in the range of 600℃ to 700℃.

Another aspect of the invention relates to the use of the apparatus according to the invention as a system for heating compounds selected from the group comprisingCdTe, CdTe: As, CdS, CdS _xTe _1-x, CdSe, CdSe _xTe _1-x, ZnTe, Cd _xZn _1-xTe, MgTe, Mg _xZn _1- _xTeand CuTe and depositing said compounds onto said substrate.

Embodiments

The invention will be explained in more detail with reference to exemplary embodiments and associated figures. The exemplary embodiments are intended to describe the invention without restricting it. The elements of the drawings are not necessarily to scale relative to each other. Like reference numbers designate corresponding similar parts.

The drawings show

Fig. 1 a first embodiment of the inventive apparatus for vapor deposition of a sublimated source material as a thin film on a substrate in a cross-section,

Fig. 2 a second embodiment of the inventive apparatus with pairs of crucible chambers in a plan view,

Fig. 3A to 3C different examples of the arrangement of more than one crucible chamber in the inventive apparatus in plan viewsand

Fig. 4 a third embodiment of the inventive apparatus with a shutter and a separate vacuum pump at the crucible chamber in a cross-section.

FIG. 1 shows the schematic structure of a firstembodiment 1 of the apparatus for vapordeposition of a sublimated source material as a thin film on a substrate according to the invention, summarized as a new closed space sublimation (CSS) concept, in a cross-sectional view.

The apparatus 1 comprises a vacuum chamber 10 and a crucible chamber 20 located outside of the vacuum chamber 10. Acrucible 21 inside the crucible chamber 20 contains an evaporation source material 22 andis heated by crucible heaters 23. After reaching a certain temperature, the evaporation source material22 evaporates and the sublimated source material vapor is transferred from the crucible chamber 20 to the vacuum chamber 10 via avapor distributor 30. The vapor distributor 30 is heated by distributor heater 31 to keep the sublimated source material vapor at a certain temperature preventing deposition of the sublimated source material within the vapor distributor 30. The sublimated source material vapor is injected onto a substrate 2to be coated underneath the vapor distributor 30 via openings32 of the vapor distributor 30. The substrate 2 is supported by atransportation system 11, wherein the transportation system 11 comprises rollers on which the flat substrate2, for example glass, is supported. The substrate 2 is heated by asubstrate heater 12, which is located underneath said substrate2. The vacuum chamber 10 and the crucible chamber20may bepumped down by a vacuum system or may be filled with a gas provided by a gas supply. The vacuum system and the gas supply may be connected to the vacuum chamber 10 using a flange 13.

The distributor heater 31 may be arranged on the outside of the vapor distributor 30 as shown in Fig. 1 or may be integrated in a wall of the vapor distributor 30.

The vacuum chamber 10 and the crucible chamber 20 may be arranged such that there is a distance between the walls of the chambers, as shown in Fig. 1. In this case, a heat isolator 40 may surround the vapor distributor 30 in the gap between the vacuum chamber 10 and the crucible chamber 20 to prevent cooling down of the sublimated source material vapor within the vapor distributor 30. However, the vacuum chamber 10 and the crucible chamber 20 may also be arranged adjacent to each other such that there is no gap between them.

It is possibleto vent the vacuum chamber 10 and the crucible chamber 20 if the crucible 21 inside the crucible chamber 20 is empty, i.e. all or most of the evaporation source material 22 is evaporated. Afterwards, acover 24of the crucible can be opened and the evaporation source material 22can be refilled. After refilling, the vacuum chamber 10and the crucible chamber 20 are pumped down again.

Fig. 2 shows a second embodiment 1’of the inventive apparatus in a plan view. In this case, the apparatus 1’comprises a plurality of crucible pairs 201 to 204, in the example of Fig. 2 four crucible pairs, in order to achieve better layer homogeneity of the deposited material. Each crucible pair 201 to 204 comprises a left-side crucible chamber 20a and a right-side crucible chamber 20b, wherein left-side and right-side refer to a transportation direction in which the substrate 2 is transported through the vacuum chamber 10. To this extend, the vacuum chamber 10 comprises an inlet load lock 14 through which the substrate 2 enters the vacuum chamber 10 and an outlet load lock 15 through which the substrate 2 leaves the vacuum chamber 10. The substrate 2 is moved into the transportation direction (indicated by the arrow in Fig. 2) within the vacuum chamber 10 by the transportation system 11 comprising a plurality of rollers or shafts. In one crucible pair 201 to 204, the left-sidecrucible chamber 20a is located on the left of the vacuum chamber 10and the right-side crucible chamber 20b is located on the right of the vacuum chamber 10.

If necessary, the left-sidecrucible chamber 20a and the right-side crucible chamber 20b may feed different sublimated source material vapors into the vapor distributor30 to mix before the vapors exit the openings 32 of the vapor distributor 30. The openings 32 are formed on the underside of the vapor distributor 30 and can in principle not be seen in a plan view, but are shown by dashed lines to illustrate them in Fig. 2. In order to improve homogeneity of the layer composition of the materialdeposited on the substrate 2, the arrangement of the different materials may change in each crucible pair 201 to 204. That is, in the first crucible pair 201, a first evaporation source material is provided within the left-side crucible chamber 20a and a second evaporation source material is provided within the right-side crucible chamber 20b, wherein the second evaporation source material is different from the first evaporation source material. In the second crucible pair 202, the evaporation source materials are provided vice versa, i.e. the second evaporation source material in the left-side crucible chamber 20a and the first evaporation source material in the right-side crucible chamber 20b. The third crucible pair 203 may be formed in the same way as the first crucible pair 201, whereas the fourth crucible pair 204 may be formed in the same way as the second crucible pair 204.

In the exemplary embodiment of Fig. 2, only one vapor distributor 30 is used for boththe left-side crucible chamber 20a and the right-side crucible chamber 20b, wherein the sublimated source materials from the left-side crucible chamber 20a and from the right-side crucible chamber 20b mix with each other within the vapor distributor 30. Other examples for arrangement of the crucible chambers and for delivering the sublimated source materials of individual crucible chambers to the substrate are explained with respect to Figures 3A to 3C, which are plan views onto the respective embodiments. These arrangements may be used for different source materials in the different crucible chambers or for the same source material in the different crucible chambers. Furthermore, the arrangements may be extended to more than two different crucible chambers, for instance three or four crucible chambers.

Fig. 3A shows two

individual crucible chambers

20a and 20b arranged on different sides of the vacuum chamber 10. Each

crucible chamber

20a and 20b has its

own vapor distributor

30a or 30b, respectively, which is connected only to its respective crucible chamber. That is, the sublimated source material from crucible chamber 20a is applied to the substrate via openings 32a in the vapor distributor 30a, whereas the sublimated source material from crucible chamber 20b is applied to the substrate via openings 32b in the vapor distributor 30b. The

vapor distributors

30a and 30b may be arranged very close to each other along the transportation direction of the substrate and the

openings

32a and 32b may be arranged in an interdigitated or staggered manner.

Fig. 3B shows an exemplary arrangement of two

crucible chambers

20a and 20b which looks very similar to that of Fig. 2. However,

eachcrucible chamber

20a and 20b is connected to its own vapor channel within the vapor distributor 30 and each vapor channel has its

own openings

32a or 32b, respectively. That is, the sublimated source material from crucible chamber 20a is applied to the substrate via openings 32a in the vapor distributor 30, whereas the sublimated source material from crucible chamber 20b is applied to the substrate via openings 32b in the vapor distributor 30. The vapor channels are formed, for instance, as tubes separated from each other, wherein the tubes may cross each other or may be arranged in any other way corresponding to the arrangement of the

openings

32a and 32b. In the example of Fig. 3B, the

openings

32a and 32b are arranged in columns each containing one opening 32a and one opening 32b and extending along the transportation direction of the substrate. In adjacent columns, the order of the

openings

32a and 32b along the transportation direction changes. The shown arrangement is only an example and may be extended, for instance with respect to the number of

openings

32a and 32b in one column, or the

openings

32a and 32b may be arranged in anyother manner.

According to the examples of Figs. 3A and 3B, the sublimated source materials of the

crucible chambers

20a and 20b mix with each other only after leaving the vapor distributor 30 or the

vapor distributors

30a and 30b through the

openings

32a and 32b.

Fig. 3C shown an exemplary arrangement, wherein the sublimated source materials of the

crucible chambers

20a and 20b mix with each other before leaving the vapor distributor through its openings. In this case, both

crucible chambers

20a and 20b are arranged on the same side of the vacuum chamber 10. Each

crucible chamber

20a and 20b has an own part of the vapor distributor, i.e. the

individual parts

301a and 301 b connecting the inside of the

respective crucible chamber

20a or 20b with a mixing part 302 of the vapor distributor. In the mixing part 302, the sublimated source materials of the

crucible chambers

20a and 20b at least partially mix with each other before entering an outlet part 303 of the vapor distributor. The outlet part 303 is arranged within the vacuum chamber 10 and comprises the openings 32 through which the mixed source materials are injected to the substrate. Again, the shape, number and arrangement of the openings may be any kind suitable for achieving good homogeneity of the film formed on the substrate.

Although the openings 32 in the vapor distributor or vapor distributors shown in Figures 2 and 3A to 3C are shown as being circular holes, the openings may have also other shapes and may be provided in other numbers and be arranged in different manners over the vapor distributor.

Fig. 4 shows a third embodiment 1” of the inventive apparatus in a cross-sectional view. Most components of this embodiment are similar to that of the first embodiment 1 and are therefore not explained again. However, the third embodiment 1” comprises a shutter 50 arranged between the vacuum chamber 10 and the crucible chamber 20 and suitable for opening or closing the vapor distributor 30. That is, the shutter 50 may be moved up and down (indicated by the arrow) , for instance, wherein the inside of the vacuum chamber 10 is vacuum-tide separated from the inside of the crucible chamber 20 if the shutter 50 is in the closing state shown in Fig. 4. Therefore, the crucible chamber 20 may be vented and opened without affecting the atmosphere within the vacuum chamber 10. That is, the vacuum chamber 10 may keep the processing atmosphere and it is even possible to proceed with the processing of substrates if sublimated source material from other crucible chambers can be provided. Thus, even if the crucible chamber 20 is empty, i.e. does not contain sufficient source material anymore, the vacuum chamber 10 has not to be vented and afterwards evacuated and the processing has not to be interrupted in order to refill the crucible 21 within the crucible chamber 20.In order to vent and evacuate the crucible chamber 20 separately from the vacuum chamber 10, the crucible chamber 20 comprises a flange 25 for a vacuum pump and/or a gas supply.

The advantages of the new CSS concept can be summarized as follows: Firstly, the temperature of the sublimated source material vapor inside the vapor distributor 30 is mainly controlled by the temperature of the vapor distributor 30, which can be adjusted more easily by adjusting the heating power of the distributor heater 32. Secondly, the requirement on the heating homogeneity of the crucible 21 inside the crucible chamber 20 is less compared to the prior art, since the vapor temperature is mainly controlled by the temperature of the vapordistributor 30, and it is not so critical to have the crucible temperature uniform. It is also easier to control the uniformity of material deposition over the whole width of the substrate 2 using the vapor distributor 30. Thirdly, the vacuum chamber 10 and the crucible chamber 20 are separated from each other and the crucible within the crucible chamber 20 may be refilled without stopping the processing in the vacuum chamber 10. Last but not least, the substrate 2to be coated can be much more easily supported by a belt or rollersand may be heated to temperatures above 550℃, in particular also glass substrates. The last advantage may be achieved when the substrate is arranged underneath the vapor distributor.

List of Reference Signs

1, 1 ‘, 1 “ apparatus für vapor deposition

2 substrate

10 vacuum chamber

11 transportation system

12 substrate heater

13 flange for vacuum pump and/or gas supply

14 inlet load lock

15 outlet load lock

20 crucible chamber

20a left-side crucible chamber

20b right-side crucible chamber

21 crucible

22 evaporation source material

23 crucible heater

24 cover of crucible chamber

25 flange for vacuum pump and/or gas supply

30, 30a, 30b vapor distributor

31 distributor heater

32, 32a, 32b openings of distributor

40 heat isolation

50 shutter

201-204 crucible pair

301a, 301 b individual part

302 mixing part

302 outlet part

Claims

An apparatus for vapor deposition of a sublimated source material as a thin film on a substrate, the apparatus comprising:

a vacuum chamber and at least one separate crucible chamber containing a crucible and being located outside and on one side next to the vacuum chamber, whereinsaid crucible chamber and said vacuum chamber are connected via a vapor distributor for distributing the sublimated source material of the crucible of the crucible chamber into the vacuum chamber; wherein,

-said vapor distributor comprises a distributor heater for heating the vapor distributor and openings for injecting the sublimated source material onto the substrate, and

-said vacuum chamber comprises a transportationsystem for supportingsaid substrate and a substrate heater for heating said substrate.
The apparatus according to claim 1, wherein, within the vacuum chamber, the substrate is arranged underneath the vapor distributor and the substrate heater is arranged underneath the transportation system.
The apparatus according to claim 1 or 2, wherein the apparatus comprises two separate crucible chambers, both located outside said vacuum chamber.
The apparatus according to claim 3, wherein both crucible chambers are connected to one vapor distributor.
The apparatus according to claim 3 or 4, wherein a first crucible chamber is located on a left side of said vacuum chamber and a second crucible chamber is located one a right side of said vacuum chamber.
The apparatus according to anyone of claims 3 to 5, wherein the crucibles each contain different sublimated source materials.
The apparatus according to claims 4 and 6, wherein vapors of said different sublimated source materials are fed into the one vapor distributor and are mixed before the vapors are injected via said openings of the vapor distributor onto the substrate.
The apparatus according to anyone of the preceding claims, wherein the crucible chamber has a cover for refilling the crucible with evaporation source material.
The apparatus according to one of the preceding claims, further comprising a carrier gas source suitable for providing a carrier gas to the crucible chamber for carrying vapor of the sublimated source material via said vapor distributor to the substrate.
The apparatus according to one of the preceding claims, wherein said substrate is of glass.
The apparatus according to anyone of the preceding claims, wherein the temperature of the substrate is in the range of room temperature to 800℃.
The apparatus according to anyone of the preceding claims, wherein the temperature of the crucible is in the range of 200℃ to 1000℃.
The apparatus according to anyone of the preceding claims, wherein the temperature of the vapor distributor is in the range of 200℃ to 1000℃.
Use of the apparatus according to claims 1 to 16 for heating a compoundselected from the group comprisingCdTe, CdTe: As, CdS, CdS _xTe _1-x, CdSe, CdSe _xTe _1-x, ZnTe, Cd _xZn _1-xTe, MgTe, Mg _xZn _1-xTe and CuTeand depositing said compounds onto said substrate.