APPARATUS AND METHOD FOR LAYER THICKNESS MEASUREMENT FOR A VAPOR DEPOSITION METHOD

Abstract

A measuring assembly and method for layer thickness measurement of a layer applied to a substrate by means of a vapor deposition method includes a measuring head which is provided with at least one vibration plate, an extraction line which can be coupled in a gas-conducting or vapor-conducting manner with a first end having a vacuum chamber for the vapor deposition method and which can be coupled in a gas-conducting or vapor-conducting manner with an opposite second end having the measuring head, wherein the extraction line includes at least one heating section or at least one cooling section.

Claims

1. A measuring assembly for measuring the layer thickness of a layer that is capable of being applied to a substrate by means of a vapor deposition method, said measuring assembly comprising: a measuring head provided with at least one vibration plate; an extraction section which by way of a first end is capable of being coupled in at least one of a gas-conducting and a vapor-conducting manner to a vacuum chamber for the vapor deposition method, and by way of an opposite second end is capable of being coupled in at least one of a gas-conducting and a vapor-conducting manner to the measuring head; wherein the extraction section has at least one of a heating portion and a cooling portion.

2. The measuring assembly as claimed in claim 1, wherein the extraction section adjacent to the first end thereof has a heating portion.

3. The measuring assembly as claimed in claim 2, wherein the extraction section adjacent to the second end thereof has a cooling portion.

4. The measuring assembly as claimed in claim 2, wherein the extraction section has at least one of a gas-conducting tube and a vapor-conducting tube that extends between the vacuum chamber and the measuring head and in the region of the heating portion is surrounded by a heater.

5. The measuring assembly as claimed in claim 3, wherein the extraction section in the region of the cooling portion has a cooling trap having at least one side wall portion that is capable of being actively cooled.

6. The measuring assembly as claimed in claim 3, wherein an internal cross section of the cooling portion is perfusable by at least one of a gas and a vapor and is larger than an internal cross section of the heating portion that is perfusable by the at least one of the gas and the vapor.

7. The measuring assembly as claimed in claim 3, wherein the cooling portion and the heating portion are mutually separated in a longitudinal direction of the extraction section.

8. The measuring assembly as claimed in claim 3, wherein at least one of at least one heating output of the heating portion and at least one cooling output of the cooling portion is capable of being regulated.

9. The measuring assembly as claimed in claim 2, wherein the heating portion occupies at least about 50% to about 90% of an overall length of the extraction section.

10. The measuring assembly as claimed in claim 3, wherein the cooling portion occupies at most about 10% to about 50% of an overall length of the extraction section.

11. The measuring assembly as claimed in claim 1, wherein the measuring head has at least two vibration plates disposed on a rotatable support and selectively movable into a region of a housing opening of a housing of the measuring head, said housing opening being disposed in an extension of the second end of the extraction section.

12. The measuring assembly as claimed in claim 11, wherein a sealing insert is inserted into the housing opening of the housing of the measuring head and in an interior of the housing is capable of coming to bear in a sealing manner on the support.

13. A method for measuring the layer thickness of a layer that is capable of being applied to a substrate by means of vapor deposition, using a measuring assembly as claimed in claim 1, the method comprising: extracting a material vapor from the vacuum chamber and directing the extracted material vapor into the extraction section; actively heating or cooling the at least one of the heating portion and the cooling portion of the extraction section; measuring a vapor deposition rate on the second end of the extraction section that faces away from the vacuum chamber by means of the at least one vibration plate.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0050] Further objectives, features, and advantageous design embodiments of the invention will be explained in the detailed description hereafter of exemplary embodiments with reference to the accompanying drawing figures.

[0051] FIG. 1 shows a schematic illustration of an exemplary embodiment of the measuring assembly in a first cross section.

[0052] FIG. 2 shows a further schematic illustration of the measuring assembly in a second cross section.

[0053] FIG. 3 shows an enlarged diagram of the second end of the extraction section of the measuring assembly.

[0054] FIG. 4 shows a further enlarged illustration of a transition region between the extraction section and the measuring head of the measuring assembly.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0055] A measuring assembly 10 for measuring the layer thickness of a layer that is capable of being applied to a substrate by means of vapor deposition is shown in FIGS. 1 and 2. The measuring assembly 10 is linked to the vacuum chamber 20 in which the substrate 24 that is to be typically applied is disposed. Within the vacuum chamber 20 the substrate is subjected to a surface-treatment process, for example a coating procedure. The coating methods can include the most diverse coating methods, typically physical or chemical vapor deposition methods. The vacuum chamber 20 is conceived for coating substrates for applications in displays or for solar cells, for example.

[0056] The vacuum chamber 20 can be configured in particular for generating a plasma that is provided for the coating process. To this extent, the vacuum chamber 20 is also suitable for plasma-facilitated coating methods. The vacuum chamber 20 is configured for coating substrates 24 with selenium, for example. The measuring assembly can serve inter alia for measuring the layer thickness of a selenium layer on the substrate 24 or on other layers that have already been applied to the substrate 24.

[0057] The measuring assembly 10 has an extraction section 12 which is capable of being coupled or is coupled, respectively, in a gas-conducting or vapor-conducting manner to the vacuum chamber 20. The extraction section 12 by way of a first end 12a is coupled in a gas-conducting or vapor-conducting manner to the vacuum chamber 20. Furthermore, the extraction section 12 by way of the end 12b thereof that faces away from the vacuum chamber 20, that is to say by way of a second end 12b, is capable of being coupled in a gas-conducting or vapor-conducting manner to the measuring head 30. In the present exemplary embodiment it is coupled permanently to the measuring head 30. As will yet be explained later with reference to FIGS. 3 and 4, the measuring head has at least one vibration plate 50, 52, the resonance or vibration behavior of the latter being electrically measurable, said resonance or vibration behavior being modified in a measurable manner as a result of an accumulation of material.

[0058] The vibration plate 50, 52 typically is cooled such that the vapor flow that is supplied to the vibration plate 50, 52 is subjected to condensation on the vibration plate, the vaporous or gaseous material as a result thereof accumulating on the vibration plate and thus modifying the vibration behavior of the latter in a measurable manner.

[0059] A proportion of the material vapor that is generated in the vacuum chamber 20 is capable of being diverted from the chamber 20 by means of the extraction section 12. Constant settling or constant condensing of the respective vaporous material within the chamber would not be implementable by virtue of the thermal conditions prevailing in said chamber. The vaporous or gaseous material by means of the extraction section 12 can be conveyed into a region that is remote from the vacuum chamber 20 and where the thermal conditions that are suitable for measuring the layer thickness and the respective pressure conditions can be created without adversely influencing the coating procedure per se that takes place in the vacuum chamber 20.

[0060] The extraction section 12 on the first end 12a thereof or adjacent to the latter has a heating portion 16 which is provided by means of a heater 26 shown in FIG. 2. In particular, the extraction section 12 has a vapor-conducting tube 14 which extends from the vacuum chamber 20 up to the measuring head 30. The tube 14 in the region of the heating portion 16 is surrounded by the heater 26. The heater 26 can have individual heat helix which at a predefined spacing wind themselves helically about the tube 14.

[0061] The heater 26 or the heating helix thereof, respectively, is presently disposed on the internal side of a sleeve 25 that encloses the tube 14. The tube 14 by means of the heater 26 can be maintained at a predefined temperature level such that premature condensing of the vaporous material that is guided in the tube is prevented.

[0062] The extraction section 12 furthermore has a cooling portion 18 which is located at the second end 12b of the extraction section 12. The cooling portion 18 can be directly adjacent to the heating portion 16. Said cooling portion 18 can however also be designed so as to be separate from the latter or so as to be thermally decoupled from the heating portion 18. The cooling portion 16 is designed in particular as a cooling trap and is provided with a dedicated cooler 29. In particular, the cooler 29 can have a cavity structure in at least one side wall 27 of the cooling portion 18. Said cavity structure can be impinged by a cooling medium and accordingly be perfused by a cooling medium that is at a predefined temperature level, for example.

[0063] A connector port 22 for a flow-technological coupling between the extraction section 12 and the measuring head 30 is provided on an end of the cooling portion 18 that faces away from the vacuum chamber 20. Furthermore, an inflow 18a and an outflow 18b for the cooling or chilling means are shown in the illustration according to FIGS. 1 and 2. Water at room temperature or below the latter can be considered as a suitable cooling or chilling means, for example. The cooling portion 18, the heating portion 16, and the inflow 18a and the outflow 18b are mechanically interconnected by means of flange plates 21, 23 that are mutually spaced apart in the longitudinal direction.

[0064] It can be clearly identified by means of FIGS. 1 and 2 that the cooling trap 28 that is provided at the downstream end of the extraction section 12 has an internal cross section QK which is larger than the internal cross section QH of the heating portion 16 that is upstream of QK. In relation to the length of the extraction section 12, the cooling portion 18 can provide an internal wall face that is larger than that of the heating portion 16 and thus provide a comparatively high cooling output per unit length. By way of the enlarged internal surface per unit length of the cooling portion 18 as compared to that of the heating portion 16, cooling that is unabated or is barely compromised by condensation of the cooling portion 18 can be performed even in the case of condensation setting in on the internal walls of said portion.

[0065] The combination of the heating portion 16 and a cooling portion 18 disposed downstream is advantageous to the extent that a formation of condensate along the extraction section 12 is largely suppressed by means of the heating portion, and almost all vapor that is extracted from the vacuum chamber 20 can thus be conveyed to that end of the heating portion 16 that faces away from the vacuum chamber 20. Condensing of the supplied material vapor that is monitored or is capable of being regulated, respectively, can take place there as the vapor arrives in the cooling portion 18, in order for the total amount of condensate on the vibration plate 50, 52 to be reduced to a minimum.

[0066] A steady and uninterrupted vapor flow can be guided into the region of the vibration plate 50, 52 by means of the heating portion 16. The total amount or the condensation rate of the vaporous medium on the vibration plate 50, 52 can be reduced to a minimum by means of the cooling portion 18 and of the cooling trap 28 that is provided with a cooler 29. In this way, the life span and the service life of the vibration plate 50, 52 can advantageously be prolonged.

[0067] The length of the heating portion 16 is typically larger than the length of the cooling portion 18 that in the longitudinal direction is adjacent to the former. The heating portion 16 is typically at least twice, three times, or four times the length of the cooling portion 18. The specific geometric design embodiment and dimensioning of the heating portion 16 and the cooling portion 18 can be adapted to the respective process in the vacuum chamber 20 as well as to the material to be measured. In particular, the layer thickness of a selenium layer on a substrate 24 can be measured by means of the measuring assembly 10 described here.

[0068] In the design embodiment according to FIG. 3 the vapor-conducting tube 14 is illustrated as a single tube that extends directly from the vacuum chamber 20 up to the measuring head 30 and which in the region of the heating portion 16 and in the region of the cooling portion 18 has a tubular geometry that is identical in each case. However, the tube 14 in the region of the cooling portion 18 is cooled while said tube 14 in the region of the heating portion 16 is warmed or heated, respectively.

[0069] By contrast, the alternative design embodiment according to FIGS. 1 and 2 provides a design embodiment of the vapor-conducting extraction section 12 in two parts. There, the vapor-conducting tube 14 at the downstream end of the heating portion 16 transitions into the radially extended cooling portion 18.

[0070] The tube 14, or the extraction section 12 that is formed by the former, respectively, at the end at the side of the measuring head is designed so as to be largely open, as can be derived from the enlarged illustration of FIG. 4. The exit of the extraction section 12, or the second end 12b of the extraction section 12, respectively, is disposed so as to be approximately in line with a housing opening 36 of the housing 34 of the measuring head. The measuring head 30 in the interior of the housing 34 thereof has a rotatably mounted support 32 which between various discrete positions is rotatable or adjustable, respectively, in relation to a rotation axis 33.

[0071] In the position illustrated in FIGS. 3 and 4, the support 32 is aligned in such a manner in the housing 34 that a vibration plate 50 that is disposed on the support 32 comes to lie so as to be approximately in line with the housing opening 36. The respective vibration plate 50 is thus exposed to the material vapor that is supplied by way of the extraction section 12. The vibration plate 50, configured as a quartz plate, for example, can be excited to perform vibrations, the frequency of the latter being measurably modified as previously vaporous condensed material accumulates.

[0072] At least one further vibration plate 52 which in the illustration according to FIG. 3 comes to lie in a region in the interior of the housing 34 that is outside the housing opening 36 is disposed on the support 32.

[0073] The housing opening 36 is furthermore provided with an insert 40, said insert functioning as a sealing insert. The latter has an outwardly protruding flange portion 42 which in the fitted position shown in FIG. 4 bears from the outside on the periphery of the housing opening 36.

[0074] The sealing insert 40 is furthermore provided with a port 44 that protrudes into the housing opening 36. The port 44 by way of the free end thereof that protrudes into the housing 34 comes to bear on a seal 46 which is configured as a sealing disk, for example, and is disposed on the internal side of the housing 34. The sealing insert 40 and the seal 46 are capable of being brought to bear on one another in a gas-tight or fluid-tight manner such that the vibration plate 52 that is disposed outside the housing opening 36 and in the interior of the housing 34 is largely protected against material vapor that intrudes into the housing 34.

[0075] The seal 46 or the annular seal, respectively, is typically provided with a material having positive friction properties such that a sealing arrangement between the seal 46 and the sealing insert 40 can be achieved in a relatively simple manner and with low friction. The provision of the seal 46 in the gap between the housing 34 of the measuring head 30 and the support 32 that is rotatably mounted in the former can furthermore largely suppress any dissemination of the material vapor in the interior of the housing 34. The vibration plates 52 that are not in the operative position can thus be largely protected against premature condensing of material vapor.

[0076] The housing 34, the support 32, and the measuring head are typically made from a heat-resistant and acid-resistant material, for example from a steel of corresponding grade. The seal 46 can be made from pyrolytic boron nitride (PBM) or polyether ether ketone (PEEK), for example.

[0077] The use of materials that have a resistance of this type and advantageously have low friction for the housing 34, the support 32, for the sealing insert 40 and the seal 46 at the side of the housing, enable a free-moving replacement of vibration plates 50, 52 by rotating the support 32 relative to the housing 34. Furthermore, said materials of the measuring assembly 10 impart a high life span and service life.

[0078] Should a vibration plate 40 that is in the operative position in FIG. 4 be populated with condensed material in such a manner that said vibration plate 40 loses its vibration properties, another new vibration plate 52 can be moved into the operative position on the housing opening 36 by simply rotating the support 32 in relation to the housing 34.