DEVICE AND METHOD FOR COATING CHANNELS OF A SAMPLE BY MEANS OF VAPOR DEPOSITION

Abstract

A method for coating one or more channels of a sample using a vapor deposition includes alternatingly supplying at least two gaseous precursor to one or more channels defined in a sample through at least one feed line that is connected to a first channel end of the one or more channels. An adjustable pressure gradient is generated and conducts the at least two gaseous precursors along a first flow direction (SR1) from the at least one feed line to a first discharge line through the one or more channels. The at least two gaseous precursor and reaction products are discharged from the one or more channels through a first discharge line that is connected to a second channel end of the one or more channels of the sample. Non-reacted precursors and reaction products are discharged through a second discharge line that is connected to the first channel end.

Claims

1-15. (canceled)

16. A device for coating channels by means of vapor deposition, comprising: at least one feed line connected to a first channel end of one or more channels of a sample, wherein the at least one feed line is configured to supply a gaseous precursor into one or more channels of a sample; a first discharge line positioned opposite the first channel end and connected to a second channel end of the one or more channels of the sample, wherein the first discharge line is configured to discharge the gaseous precursors and reaction products emerging from the one or more channels of the sample; a second discharge line connected to the first channel end of the one or more channels of the sample; and a control unit configured to alternatingly supply at least two different gaseous precursors to the at least one channel through the first channel end via the at least one feed line, wherein a pressure gradient is generated and is configured to supply the gaseous precursor along a first flow direction (SRI) from the feed line through the one or more channels of the sample, and wherein the pressure gradient is configured to discharge unreacted precursors and reaction products via the second discharge line along a second flow direction (SR2).

17. The device according to claim 16, wherein the control unit is configured to adjust the pressure gradient by means of a volumetric flow rate of the at least two gaseous precursors that are supplied through the at least one feed line.

18. The device according to claim 16, wherein the control unit is configured to adjust the pressure gradient by means of a volumetric flow rate of the at least two gaseous precursors that flows into the first discharge line.

19. The device according to claim 16, wherein the control unit is configured to supply an inert gas to the sample as a flushing gas during discharge.

20. The device according to claim 19, wherein the control unit is configured to conduct the flow of the at least two gaseous precursors through the one or more channels of the sample in the first flow direction (SR1) and a flow of the inert gas in the second flow direction (SR2), wherein the second flow direction (SR2) is opposite that of the first flow direction (SR1).

21. The device according to claim 19, wherein the control unit is configured to adjust the pressure gradient by adjusting a volumetric flow rate of the inert gas, wherein the inert gas is supplied to the second channel end via a feed line configured to be connected to the second channel end.

22. The device according to claim 16, wherein the control unit is configured to increase the pressure gradient as a diameter of the one or more channels of the sample decreases as a result of deposition of material on an inner surface of the one or more channels.

23. The device according to claim 16, wherein the control unit is configured to adjust the pressure gradient to maintain a Knudsen flow in at least in some sections of the one or more channels during deposition of material on an inner surface.

24. The device according to claim 16, wherein the one or more channels of the sample comprise an aspect ratio of greater than 1:1,000.

25. The device according to claim 16, wherein the one or more channels of the sample comprise an aspect ratio greater than 1:20,000.

26. The device according to claim 25, wherein the one or more channels comprise a diameter of less than one (1) micrometer.

27. A method for coating one or more channels of a sample using a vapor deposition, comprising: alternatingly supplying at least two gaseous precursor to one or more channels defined in a sample via at least one feed line that is connected to a first channel end of the one or more channels of the sample; generating an adjustable pressure gradient that is configured to conduct the at least two gaseous precursors along a first flow direction (SR1) from the at least one feed line to a first discharge line through the one or more channels; discharging the at least two gaseous precursor and reaction products from the one or more channels through a first discharge line that is connected to a second channel end of the one or more channels of the sample, wherein the second end is positioned opposite the first end; and discharging non-reacted precursors and reaction products through a second discharge line that is connected to the first channel end.

28. The method according to claim 27, wherein the adjustable pressure gradient is set using a volumetric flow rate of the at least two gaseous precursors supplied through the at least one feed line.

29. The method according to claim 27, wherein the adjustable pressure gradient is set using a negative pressure that is applied to the first discharge line.

30. The method according to claim 27, further comprising supplying an inert gas to the sample as a flushing gas during the discharging.

31. The method according to claim 30, wherein the inert gas is conducted along a second flow direction (SR2) that is opposite the first flow direction (SR1), and wherein the inert gas and the at least two gaseous precursors are alternatingly conducted through the one or more channels of the sample.

32. The method according to claim 27, wherein the pressure gradient is generated by a volumetric flow rate of an inert gas, and wherein the inert gas is supplied to the second channel end through a feed line that is connected to the second channel end.

33. The method according to claim 27, wherein the adjustable pressure gradient is increased as a diameter of the one or more channels of the sample decreases due to a deposition of material on an inner surface of the one or more channels.

34. The method according to claim 27, wherein a Knudsen flow is maintained at least in some sections within the one or more channels of the sample during the vapor deposition.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] An embodiment of the invention is explained in the following other figures.

[0023] FIG. 1 schematically illustrates an example of a prior art device for vapor deposition.

[0024] FIG. 2 schematically illustrates an embodiment of the inventive device for vapor deposition.

[0025] If not otherwise specified, the same reference numbers indicate the same objects below.

DETAILED DESCRIPTION OF THE INVENTION

[0026] A device for vapor deposition, in particular for atomic layer deposition, according to the prior art is illustrated in FIG. 1. This device comprises a large reaction chamber 100, to which a first precursor is supplied from a reservoir 104 via a feed line 102 and a second precursor is supplied from a reservoir 108 via a feed line 106. Naturally, additional precursors can also be supplied via these feed lines or additional feed lines. In addition to the material that is to be deposited, the precursors can also comprise an inert gas as a carrier gas. The two precursors are distributed evenly in the evacuated reaction chamber 100 by diffusion and, in the process, also adhere to a sample 114, and thus react with the sample. The sample 114 can be retained on a sample holder, which is not shown. The precursors are supplied to the chamber 100 alternatingly and react on the sample surface to form atomic layers. For example, atomic layers of metal oxides, in particular AL2O3, can be formed on the sample. The reaction chamber can be evacuated via a discharge line 110 and a vacuum pump 112 that is attached to it. In particular, the chamber can also be flushed via the discharge line 110 and a feed line for inert gas, which is not shown.

[0027] Surfaces of a sample can generally be coated well with a known reaction chamber such as this. Nevertheless, the internal structures, especially the inner surfaces of channels, cannot be coated successfully or only with inefficiently long process times. This is due in particular to the fact that the precursors cannot be diffusively distributed, or only very slowly, along the interior of the channels.

[0028] A device according to the invention is illustrated schematically in FIG. 2. This device for coating channels by means of vapor deposition comprises a sample 12 with channels 13 that are formed within it. The sample can be arranged in a sample holder, which is not shown. The device further comprises a first feed line 14 for supplying a first gaseous precursor from a reservoir 18 and a second feed line 16 for supplying a second precursor from a reservoir 20. The feed lines 14, 16 are connected to a first channel end 13a of the channels 13 formed in the sample 12. Furthermore, the device comprises a first discharge line 22, which is connected to the first channel ends 13a lying opposite the second channel ends 13b of the channels 13. A vacuum pump 24 is connected to the first discharge line 22.

[0029] During a deposition process, the first precursor and the second precursor are supplied alternatingly to the first channel ends 13a via the first feed line 14 and via the second feed line 16, respectively. A negative pressure is generated in the first discharge line 22, and thus at the second channel ends 13b, by means of the vacuum pump 24. Different pressure conditions thus exist in the area of the first channel ends 13a and in the area of the second channel ends 13b, which leads to the establishment of a pressure gradient. Owing to the pressure gradient, a precursor flow of first precursor and second precursor, respectively, is generated along a first flow direction SR1 from the first channel ends 13a through the channels 13 via the second channel ends 13b to the first discharge line 22. As a result of the pressure gradient, the precursors reliably reach the entire inner surface of the channels, not only in the area of the first channel ends, but especially also in the area of the second channel ends. This leads to a coating that is complete, uniform and, due to low process times, efficient.

[0030] In an embodiment, this pressure gradient can be adjusted via a control unit 50. In particular, the control unit 50 controls the supply of the first precursor via the feed line 14, the supply of the second precursor via the feed line 16 and the discharge via the first discharge line 22. For this purpose, the control unit 50 controls valves that are provided in particular on the feed line side and/or discharge line side. The control unit 50 also controls the vacuum pump 24. For example, the control unit 50 can adjust the pressure gradient by adjusting the quantity and thus the volumetric flow rate of the precursor (possibly including the carrier gas) that is supplied via the feed lines 14, 16, or by adjusting the negative pressure applied to the first discharge line 22 by controlling the vacuum pump 24. In particular, the supply of first precursor and second precursor can be pulsed, wherein the control unit 50 can adjust the pressure gradient by controlling the duration of the pulses, for example. In particular, the control unit can set a specific pressure gradient as a function of the diameter and aspect ratio of the channels in the sample.

[0031] The device further comprises a reservoir 28 for inert gas, which can be supplied to the channels 13 via a further feed line 26, which is connected to the second channel ends 13b. In the present example, the feed line 26 is identical in some sections to the first discharge line 22. The supply of inert gas from the reservoir 28 is likewise controlled by the control unit 50. For example, the control unit 50 can supply inert gas from the reservoir 28 to the area of the second channel ends 13b via the feed line 26 in order to adjust the pressure gradient. In this way, in particular in coordination with the vacuum pump 24 and thus the discharge line 22, the pressure on the side of the second channel ends 13b can be not only reduced but also increased and therefore finely adjusted. Furthermore, flushing the channels 13 with inert gas can take place between deposition processes, i.e. between the processes of supplying the first precursor and the second precursor, respectively. For example, after the first precursor has flowed through the channels 13 along the first flow direction SR1 from the first channel ends 13a, through the channels 13 via the second channel ends 13b, a flushing process can take place in the opposite direction. Inert gas is then conducted along an opposite second flow direction SR2 from the reservoir 28 via the second channel ends 13b, through the channels 13 and via the first channel ends 13a. According to the invention, a second discharge line 30, which is connected to the first channel ends 13a, is provided. This line leads to a further vacuum pump 32, but can alternatively or additionally also be connected to the vacuum pump 24. The flow of flushing gas conducted through the channels along the flow direction SR2 is discharged via the second discharge line 30. In this way, precursors that have not entered the channels during the supplying process, as well as their reaction products and any physisorbed precursors, are discharged.

[0032] Flushing in the opposite direction allows for the most complete removal of precursors and reaction products. In particular, any accumulation of precursor molecules and/or reaction products that may have occurred in the region of the first channel ends 13a can be reliably removed in this way. In addition, precursors within the channels and physisorbed on the inner surface of the channels can also be discharged from the channels in a particularly reliable manner. These accumulations are reliably pumped away by means of the vacuum pump 32 and via the second discharge line 30. Therefore, owing in particular to the second discharge line, channels with an especially small diameter, such as in the nanometer range, and an especially large aspect ratio, such as 1:10,000, can also be coated reliably and efficiently.

[0033] The project leading to the present application has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No. 714073).

LIST OF REFERENCE SIGNS

12 Sample

[0034] 13a First channel end
13b Second channel end
14 First feed line
16 Second feed line

18 Reservoir

20 Reservoir

[0035] 22 First discharge line
24 Vacuum pump
26 Feed line

28 Reservoir

[0036] 30 Second discharge line
32 Vacuum pump
50 Control unit
100 Reaction chamber
102 Feed line

104 Reservoir

[0037] 106 Feed line

108 Reservoir

[0038] 110 Discharge line
112 Vacuum pump
114 Sample holder
SR1 First flow direction
SR2 Second flow direction