WO2019120387A1

WO2019120387A1 - Method for operating a depositing system

Info

Publication number: WO2019120387A1
Application number: PCT/DE2018/101037
Authority: WO
Inventors: Sebastian Hubertus SCHULZ; Lars GUGGOLZ; Josef Haase; Reiner Müller
Original assignee: centrotherm international AG
Priority date: 2017-12-21
Filing date: 2018-12-20
Publication date: 2019-06-27
Also published as: WO2019120358A1; WO2019120386A1

Abstract

The invention relates to a method for operating a depositing system in which a process layer is deposited (22) onto an object to be coated. Prior to depositing the process layer on the object to be coated, a reactant (42) of an undesired reaction, said reactant being accumulated on a wall (40) of a process chamber or on a wall (40) of a depositing system exhaust gas section connected to the process chamber, is chemically converted (16) into at least one product (46, 48) using a binding substance (44), and the at least one product (46, 48) is discharged from the depositing system (18).

Description

Method for operating a separation plant

The invention relates to a method according to the preamble of claim 1.

Separation plants are used in different variants to deposit layers on objects to be coated. For example, in the manufacture of semiconductor devices, such as solar cells, layers are deposited on substrates.

For the deposition of layers different technologies are used. The desired layers can be deposited in particular by means of chemical vapor deposition, which is commonly referred to as chemical vapor deposition in the English-speaking world and is abbreviated to CVD for short. A variant of the CVD technology is the plasma-assisted chemical deposition from the

Vapor phase, which in the English-speaking world is called Plasma Enhanced Chemical Vapor Deposition and hereafter PECVD. Another separation technology is the atomic layer deposition, which is known in the English-speaking world as Atomic Layer Deposition and is often called ALD for short. In addition, layers can be deposited by sputtering.

All these deposition technologies have in common that the associated separation plants have process chambers in which the deposition takes place. Furthermore, they have a Gaszufüh tion and an exhaust system. By means of the gas supply who provides the process gases required for the deposition processes, while the exhaust system sucks gases from the process chamber and in the process chamber a desired pressure ready- provides, in particular, regulates this. The aforementioned Abscheidean can be operated in batch mode or as continuous systems be.

Used exhaust systems usually have a Abgasstre bridge on which gases are removed from the process chamber by means of a vacuum pump from the process chamber. As a result, it is also in the exhaust gas line and the vacuum pump, which is part of the exhaust gas line, to Abscheidun conditions. These are generally not desirable because they can lead to cases out of the vacuum pumps used. In addition, in the described unwanted deposits ent standing and transported in an exhaust gas flow particles can lead to damage to the vacuum pump. Particles of this type can inter alia reach the exhaust gas stream as flakes from the undesirable deposits described. In many deposition processes therefore periodic maintenance of the vacuum pump are required, which significantly increase the cost of the divorce of the desired layers.

In order to reduce the cost of maintenance of the vacuum pumps, it is previously known to arrange in front of the pump sections of the exhaust system filters or traps to tiff or precipitate for the decisions in the exhaust gas relevant or the exhaust pump harmful exhaust components from the exhaust stream.

Corresponding traps can be supported chemically or thermally, as is the case for example with a cold trap. However, the use of such traps and filters is still associated with a considerable effort for maintenance and cleaning tion work, which are to be made to the filters and traps used. Depending on the subfilters to be filtered out The use of a filter can be easily implemented, complex and time-consuming or impossible.

In the present case, the term "parasitic deposition" refers to such deposits which, as a result of the deposition process, are not deposited on objects to be coated deposited in the deposition plant, but on other surfaces such as walls of process chambers, walls of the exhaust gas line or walls of the vacuum pump.

Against the background outlined, the present invention is the object of the invention to provide a method for operating a separation plant available, with which stand times of a vacuum pump of the deposition system can be extended. The term of the service life of the vacuum pump is understood to mean a period of time during which the vacuum pump can be reliably operated without having to carry out any maintenance work on the vacuum pump or the vacuum pump has to be exchanged.

This object is achieved by a method with the Merkma len of claim 1.

Advantageous developments are the subject of dependent dependent claims.

The inventive method for operating a Abscheidean situation provides that on a wall of a process chamber or on a wall connected to the process chamber exhaust line of Abscheideanlage annealed educt of an un desired reaction by means of a binding substance is chemically to set in at least one product. This at least one product is removed from the separation plant. These process steps are carried out before a process layer on a is deposited to be coated object. This is followed by the deposition of the process layer on the object to be coated.

The at least one product is removed in the present sense from the separation plant when it is removed from the process chamber and / or the exhaust line so that it can not get into a vacuum pump of the exhaust line in ge ordinary operation of the separation plant. In particular, the at least one product from the deposition system can be abge leads by it by means of the vacuum pump in a gas flow from the process chamber and an upstream of the Va kuumpumpe located section of the exhaust line is led out.

As a result of the chemical reaction of the attached starting material and its removal from the separation plant this is no longer available as starting material for the undesirable reaction. Parasi tary deposits in the vacuum pump or the formation of the vacuum pump damaging particles can be avoided in this way ver or at least reduced. Thus, extended service life of the vacuum pumps can be realized.

In the described method, for example, angela alloyed oxides can be chemically reacted by means of reducing gases who the. The same applies to the use of oxidizing gases.

In particular, a substrate, for example a silicon substrate, can be provided as the object to be coated.

Preferably, an attached gas is chemically reacted as an attached starting material. In this embodiment variant, the described method has proven particularly useful. Especially before given to the annealed gas is desorbed in the course of the chemical reaction and transferred to a gas phase. Advantageously, a gas is used as the binding substance. This can be passed in a comfortable manner in the deposition system.

A variant of the method provides that, on the wall of the process chamber and on the wall of the exhaust gas line connected to the process chamber, quantities of the educt of the undesired reaction are chemically converted into the at least one product by means of the binding substance. This allows a substantial chemical reaction of the educt and consequently a long extension of the life of the vacuum pump.

Preferably, the binding substance is provided by being introduced into the process chamber or the exhaust line connected to the process chamber. This allows, in particular in conjunction with a gaseous binding substance, a com fortable provision of the binding substance and a kontrol profiled chemical reaction of the reactant.

In a variant of the method is attached to the wall of the process chamber or attached to the wall of the exhaust line What water chemically reacted by means of the binding substance. The water is preferably attached in gaseous state of aggregation to the wall of the process chamber or the exhaust gas line. In this variant, the inventive method has proved to be advantageous. In particular, when used in the subsequent deposition of the process layer trimethylaluminum as the process gas, this process variant has FITS proven special, since in the presence of water, the Trimethylalu minium reacts with this to form alumina. Aluminum oxides, and in particular Al ₂ O ₃ , have a high degree of hardness and can therefore cause considerable damage and / or wear in the vacuum pump, which causes them Shorten the service life. This can be avoided or at least considerably reduced by means of the process variable described.

Preferably, at least one substance selected from the group consisting of methane, silane, ammonia and trimethylaluminum is used as the binding substance. Trimethylaluminium is partly called TMA for short. These substances have proven themselves in practice. Preferably silane is used.

In a particularly preferred variant silane is used as Bin desubstanz and by means of this silane annealed water, which represents the annealed educt, chemically to set. In this chemical reaction Si (OH) 4 and / or S1O2 is formed according to the fol lowing reactions:

SiH ₄ + 4 H ₂ O -> Si (OH) 4 + 4 H ₂

2 H ₂ O + SiH ₄ -> S1O 2 + 4 H ₂

Since silane is used in many deposition processes in the manufacture of semiconductor devices, by means of this variant, water, which is often the starting material of undesirable reactions, can be chemically converted relatively inexpensively and efficiently. The products formed Si (OH) 4 and / or S1O2 affect the vacuum pump significantly lower and reduce their life significantly less than, for example, the above-described, from TMA in the presence of water-forming th aluminum oxides.

Advantageously, after the described chemical reaction of the starting material, the process chamber is evacuated to a pressure in the range from 0.001 mbar to 10 mbar. Subsequently, the process chamber is purged with an inert gas. Nitrogen is preferably used as the inert gas. Under the concept of In the present case, lens is understood to mean that inert gas is introduced simultaneously and pumped out of the process chamber over a period of more than 2 minutes. Subsequently, the process chamber is again evacuated to a pressure in the range of 0.001 mbar to 10 mbar, wherein the range limits are always part of the respective pressure range in all of the pressure ranges indicated in the present application. In this way, remaining amounts of the at least one product or of the attached educt can be further removed from the process chamber and the exhaust gas line before the process layer is deposited. This allows a further extension of the service life of the vacuum pump.

A further development provides, before the chemical reaction of the educt, the process chamber to a pressure in the range of

0.001 mbar to 10 mbar to evacuate. Subsequently, the process chamber with an inert gas, preferably nitrogen, ge flushes. This again takes place before the chemical reaction of the educt. Thereafter, the process chamber is evacuated again to a pressure in the range of 0.001 mbar to 10 mbar, which in turn takes place before the chemical reaction of the educt. The term of chemical reaction of the educt always refers to the described chemical reaction of the starting material by means of the binding substance. This development represents a preparatory flushing of the process chamber, and thus also the exhaust gas line. In conjunction with the chemical reaction of the starting material and the described removal of the at least one product allows complete, or at least further removal of the starting material and thus a further extension the service life of the vacuum pump.

As an alternative or in addition to the further development described above, it can be provided that, before the chemical reaction of the starting material, the process chamber is adapted to a pressure in the process. rich from 0.001 mbar to 10 mbar is evacuated and subsequently the process chamber is filled with an inert gas to a pressure of more than 100 mbar, preferably up to a pressure of more than 500 mbar and more preferably up to ambient atmospheric pressure. This filling of the process chamber with the inert gas takes place before the chemical reaction of Edu kts. Thereafter, the process chamber is evacuated to a pressure in the range of 0.001 mbar to 10 mbar, which in turn takes place before the chemical reaction of the educt. In this approach, as in the above-described Weiterbil tion, an amount of the existing in the process chamber and / or exhaust gas reactant already be removed in advance of the chemical reaction of the starting material from the deposition plant. In conjunction with the chemical reaction of the educt and the discharge of the at least one product from the separation plant, the starting material can be completely, or at least further, removed from the reaction chamber and / or the exhaust gas line. As a result, the life of the vacuum pump can be extended ver.

Preferably, the educt is completely removed from the process chamber and the exhaust gas line. In this way, a maxi times extension of the life of the vacuum pump achieved who the.

In an advantageous embodiment variant, TMA is introduced into the process chamber for the purpose of depositing the process layer. In this way, an aluminum-containing layer, in particular an aluminum oxide layer, are deposited as a process layer on the object to be coated. In this context, the method has been particularly appreciated. The process layer is preferably deposited chemically from a vapor phase. This takes place particularly preferably plasmaunter supported, ie by means of PECVD.

Furthermore, the invention will be explained in more detail with reference to figures. As far as appropriate, elements having the same effect here are provided with the same reference numbers. The invention is not limited to the Ausführungsbeispie le shown in the figures - not even in terms of functional features. The previous description as well as the following description of the figures contain numerous features, which are partly summarized in the dependent subclaims. However, those features, as well as all other features disclosed in the following description of the figures, will also be considered individually by the person skilled in the art and put together to meaningful further combinations. In particular, all the features mentioned in each case individually and in any geeigne ter combination with the method according to claim 1 combinable bar. Show it:

Figure 1 Schematic representation of a first embodiment of the method according to the invention

Figure 2 additional or alternative process steps in a further embodiment of the erfindungsge MAESSEN method

Figure 3 is a schematic representation of an attached to a wall educt

FIG. 4 shows a schematic introduction of a binding substance

presentation Figure 5 is a schematic representation of a desorption of the angela Gerten starting material

Figure 6 shows a discharge of at least one product from the separation plant from in a schematic representation

Figure 1 illustrates, together with Figures 3 to 6 ers tes embodiment of the method according to the invention for operating a separation plant. In this process, a process chamber is first evacuated to a pressure in the range from 0.001 mbar to 10 mbar. 10. The process chamber is evacuated by means of a vacuum pump arranged in an exhaust line of the deposition plant, so that this exhaust gas line is likewise evacuated at the same time. In addition, the process chamber is purged with an inert gas 12. As the inert gas in the present Ausfüh approximately nitrogen is used. In addition, the process chamber is evacuated again 10. By means of hitherto described enclosed evacuation and rinsing steps 10, 12 is already a certain amount of an attached to a wall 40 of the process chamber or connected to the process chamber exhaust passage angelager th starting material 42 removed from the deposition plant. In the present embodiment, the deposited starting material 42 is water 42, which is shown schematically in FIG. 3.

Figure 3 shows a partial view of the wall 40, wel che to the water 42 is attached. The wall 40 may be a wall of the process chamber or a wall of the exhaust gas line.

In the further course of the process, as shown schematically in Figure 4, gaseous silane 44 as a binding substance in the process chamber or connected to the process chamber exhaust gas line initiated 14. As a result, there is an in gur 5 shown schematically desorption of the water 40 attached to the wall 40 and this is chemically reacted 16. The said chemical reaction 16 takes place in the transition from Figure 5 to Figure 6 and is indicated schematically by an arrow. In this implementation 16 Si (OH) ₄ 46 and H ₂ 48 are formed in the illustrated embodiment. The chemical cal implementation 16 of the water 42 proceeds according to the reaction:

SiH ₄ + 4 H ₂ O -> Si (OH) ₄ + 4 H ₂

The products formed Si (OH) ₄ 46 and H ₂ 48 are further removed from the separation plant 18. For this purpose, they are pumped abge from the process chamber or the process chamber with the exhaust pipe connected by means of the vacuum pump. This is shown schematically in Figure 6 by the arrow 50 represents.

In addition, the process chamber is evacuated 10 to a pressure in the range of 0.001 mbar to 10 mbar, the process chamber flushed with nitrogen 12 and the process chamber subsequently evacuated again 10. As shown in the schematic diagram of Figure 1 as dergegeben is subsequently for the purpose of deposition This is followed by a deposition 22 of an aluminum oxide layer by means of PECVD on a in the process chamber angeord Neten, to be coated object. In this case, the said aluminum oxide layer is deposited chemically from the vapor phase on the object to be coated as the process layer. The deposition is carried out with plasma assistance.

FIG. 2 illustrates further exemplary embodiments of the method. These further embodiments differ from the embodiment of FIG. 2 shows a reproduced process steps of filling 13 of the process chamber with nitrogen and the subsequent evacuation 10 of the process chamber. In the exemplary embodiment illustrated in FIG. 1, these two method steps can replace the process steps of rinsing 12 of the process chamber and the subsequent evacuation 10 of the process chamber provided prior to the chemical reaction 16 of the stored water 42.

Alternatively, it is possible to provide the method steps from FIG. 2 in addition to the method steps already shown in FIG. In this exemplary embodiment, the method steps from FIG. 2 are taken into the process step sequence from FIG. 1 before the silane is introduced into the process chamber. Thus, they are performed before chemi's reaction 16 of the stored water 42. The process steps of filling the process chamber with nitrogen and the subsequent evacuation 10 of the process chamber can be inserted into the process step sequence of fi gure 1 after the first evacuation 10 of the process chamber and before the first flushing 12 of the process chamber who or after the second evacuation step 10th By an additional recording of the process steps of Figure 2 in the process step sequence of Figure 1, as described above ben, a further extension of the service life of the vacuum pump can be realized.

Although the invention has been described in detail by preferred embodiment examples, the invention is not limited by the disclosed embodiments and other variants of the invention can be derived by those skilled in the, without departing from the spirit of the invention. LIST OF REFERENCE NUMBERS

10 evacuate process chamber

12 rinsing the process chamber

13 Fill process chamber with nitrogen

14 Introducing silane in process chamber

16 chemical reaction of the deposited water and formation of SI (OH) ₄ and / or S1O ₂

18 purging products from separation plant

20 Initiate TMA in process chamber

22 depositing aluminum oxide layer using PECVD

40 wall

42 H ₂ 0

44 SiH ₄

46 Si (OH) ₄

48 H ₂

50 pumping products

Claims

claims

A method of operating a deposition apparatus, wherein a process layer is deposited on an object to be coated (22);

d a d u r c h e c e n c i n e s that

before depositing (22) the process layer on the object to be coated

- An educt (42) of an unwanted reaction by means of a binding substance (44) is chemically reacted (16) in at least one on a wall (40) of a process chamber or on a wall (40) connected to the process chamber NEN exhaust gas line of the deposition plant Product (46, 48);

- This at least one product (46, 48) is discharged from the separation deanlage (18).

2. The method according to claim 1,

characterized ,

that as annealed educt (42) an attached gas is chemically reacted.

3. Method according to one of the preceding claims,

characterized ,

that a gas is used as the binding substance (44).

4. Method according to one of the preceding claims,

characterized ,

on the wall (40) of the process chamber and on the wall of the exhaust gas line connected to the process chamber to stored quantities of the educt (42) of the unwanted reaction by means of the binding substance (44) are chemically converted into the at least one product (46, 48) ,

5. Method according to one of the preceding claims,

characterized ,

in that the binding substance (44) is provided by being introduced into the process chamber or the exhaust gas line connected to the process chamber (14).

6. The method according to any one of the preceding claims,

characterized ,

in that water (42) attached to the wall (40) of the process chamber or to the wall of the exhaust gas line is chemically reacted by means of the binding substance (44).

7. The method according to any one of the preceding claims,

characterized ,

in that at least one substance selected from the group consisting of methane, silane (44), ammonia and trimethylaluminum is used as the binding substance (44), preferably silane (44).

8. Process according to claims 6 and 7,

characterized ,

that silane is used as the binding substance (44) and in the reaction of the water (42) Si (OH) 4 (46) and / or S1O2 is formed (16).

9. The method according to any one of the preceding claims,

d a d u r c h e c e n c i n e s that

- after said chemical reaction (16) of the educt (42), the process chamber is evacuated to a pressure in the range of 0.001 mbar to 10 mbar (10);

- Subsequently, the process chamber with an inert gas, preferably nitrogen before, is rinsed (12);

- Subsequently, the process chamber is evacuated to a pressure in the range of 0.001 mbar to 10 mbar (10).

10. The method according to any one of the preceding claims, d a d u r c h e c e n e c e s in that e

- Before said chemical reaction (16) of the educt (42), the process chamber is evacuated to a pressure in the range of 0.001 mbar to 10 mbar (10);

- Subsequently, prior to said chemical reaction (16) of the educt (42), the process chamber with an inert gas, preferably nitrogen, is rinsed (12);

- Subsequently, prior to said chemical reaction (16) of the starting material (42), the process chamber is evacuated to a pressure in the loading range of 0.001 mbar to 10 mbar (10).

11. The method according to any one of the preceding claims,

d a d u r c h e c e n c i n e s that

- Subsequently, prior to said chemical reaction (16) of the educt (42) the process chamber with an inert gas to a pressure of more than 100 mbar, preferably up to a pressure of more than 500 mbar and particularly preferably be filled to atmospheric pressure (13);

12. The method according to any one of the preceding claims,

characterized ,

the educt (42) is completely removed from the process chamber and the exhaust gas line.

13. Method according to one of the preceding claims, characterized in that

for the purpose of depositing (22) the process layer trimethylaluminum is introduced into the process chamber (20).

14. The method according to any one of the preceding claims,

characterized ,

that an aluminum-containing layer is deposited as the process layer (22).

15. The method according to claim 14,

characterized ,

that a layer of aluminum oxide is deposited as the process layer (22).