DIAPHRAGM VACUUM MEASURING CELL AND METHOD FOR THE PRODUCTION OF SUCH MEASURING CELL

• US 20080110269A1
• Filed: 11/06/2007
• Published: 05/15/2008
• Est. Priority Date: 11/13/2006
• Status: Active Grant

• Current Assignee: Inficon Holding AG
• Original Assignee: INFICON GmbH (Inficon Holding AG)
• Inventors: BERNER, Walter, STRIETZEL, Carsten, BJORKMAN, Per
• Granted Patent: US 7,536,915 B2
• Time in Patent Office: Days
• US Class Current: 73/718
• CPC Class Codes: G01L 19/0627 Protection against aggressive medium in general
• CPC Class Codes: G01L 9/0075 using a ceramic diaphragm, e.g. alumina, fused quartz, glass
• CPC Class Codes: G01L 9/0079 with Fabry-Perot arrangements

Abstract

Introduced is a method for the production of a diaphragm vacuum measuring cell, wherein on the one side of the diaphragm (2) at a spacing a first housing plate (1) is disposed sealing in the margin region with a joining means (3), and that on the other side of the diaphragm (2) at a spacing a second housing plate (4) is disposed sealing in the margin region with a joining means (3), and that the second housing plate (4) has an opening at which a connection means (5) is disposed sealing with joining means (3) for the connection of the measuring cell (8) with the medium to be measured, wherein the diaphragm (2) and the two housing plates (1, 4) are comprised of a metal oxide. Using an ALD method, the measuring cell is coated in a vacuum chamber (64), in particular through the opening of the measuring cell, such that the inner wall of the measuring vacuum chamber (9) and the opening with the connection means (5) is covered with a protective layer (13) such that at least the joining means (3) for the diaphragm (2) is protectively covered against corrosion.

Claims

1. :

Method for the production of a vacuum measuring cell with a diaphragm (2) as pressure transducer, wherein on the one side of the diaphragm (2) at a spacing a first housing plate (1) is disposed sealing in the margin region with a joining means (3), such that between them a reference vacuum chamber (7) is formed and that on the other side of the diaphragm (2) at a spacing a second housing plate (4) is disposed sealing in the margin region with a joining means (3), such that between them a measuring vacuum chamber (9) is formed, and that the second housing plate (4) includes an opening and connection means (5) communicating with such and the measuring vacuum chamber (9) disposed sealing with joining means (3) for the connection of the measuring vacuum chamber (9) with the medium to be measured, wherein the diaphragm (2) and the two housing plates (1, 4) are comprised of a metal oxide, characterized in that the measuring cell is coated in a vacuum chamber (64) using an ALD method and the material deposition takes place through the opening of the measuring cell and the connection means (5) such that the inner wall of the measuring vacuum chamber (9) and the opening with the connection means (5) is covered with a protective layer (13) such that at least the joining means (3) for the diaphragm (2) is protectively covered.

2. :

Method as claimed in claim 1, characterized in that as the metal oxide one of the aluminum oxides is utilized or that, preferably, at least the sapphire form is partially utilized.

4. :

Method as claimed in claim 1, characterized in that at least one of the joining means (3, 6) is established through friction welding.

5. :

Method as claimed in claim 1, characterized in that the connection means (5) is formed of a metal or a ceramic tubularly or as a connecting piece with a feed line, and that this means is connected with the second housing plate with a joining means (6) through a glass solder or friction welding.

6. :

Method as claimed in claim 5, characterized in simultaneously with the joining means (3, 6), the inner wall of the feed line connection means, is covered forming a protection

7. :

Method as claimed in claim 1, characterized in that at least one diaphragm measuring cell (8), preferably several diaphragm measuring cells (8), is/are placed as the substrate (63) in a vacuum chamber (64) on a substrate holder (62) which includes a heating arrangement, and subsequently the vacuum chamber (64) is evacuated with a pump system (52, 53, 54) and that, after the evacuation is completed to the desired pressure, the coating process takes place in that at least two precursor gases (57, 58) are sequentially introduced into the vacuum chamber (64) at predetermined time intervals, wherein between each of these steps the chamber is purged with an inert purge gas (65) for a predetermined time and that this cycle is repeated several times, such that from individual chemically reacted atomic coats a metal oxide layer (13) with desired total thickness is deposited.

8. :

Method as claimed in claim 7, characterized in that the coating takes place with several hundred to a few thousand cycles.

9. :

Method as claimed in claim 7, characterized in that at least a first precursor (57) is utilized which comprises a metal compound and that at least as a second, or further, precursor (58) an oxygen-containing substance, preferably H₂O, is utilized.

10. :

Method as claimed in claim 9, characterized in that the at least first precursor (57) contains the substance titanium chlorides or titanium tert-butoxides for the formation of a TiO₂ layer, or that the at least first precursor (57) comprises tantalum ethoxides for the formation of a Ta₂O₅ layer.

11. :

Method as claimed in claim 9, characterized in that the at least first precursor (57) comprises trimethyl aluminum for the formation of an Al₂O₃ layer.

12. :

Method as claimed in claim 9, characterized in that nitrogen (N₂) is utilized as the purge gas (65).

13. :

Method as claimed in claim 9, characterized in that the temperature of the substrate holder (62) is set to a value in the range of 100°

to 500E C, preferably to a value in the range of 200E to 400E C, and that this temperature is kept constant, preferably with a temperature regulation means (55).

14. :

Method as claimed in claim 9, characterized in that the deposition of the protective layer (13) within the measuring vacuum chamber (9) and the transition of the opening of the second housing plate (4) to the connection means (5) covering the joining means (3, 6) is carried out such, that at least in this region a protective layer thickness of 20 to 200 nm is attained, preferably in the range from 25 to 50 nm.

15. :

Method as claimed in claim 9, characterized in that with the contamination of the diaphragm measuring cell (8) through chlorine-containing process gases, a service life extension of the diaphragm measuring cell (8) is attained, which is greater than without the protective coating (13) by at least the factor 3, preferably by the factor 5 to 20.

16. :

Method as claimed in claim 9, characterized in that the first and the further precursor (58, 57) as well as the purge gas (65) are sequentially introduced into the vacuum chamber (64) with valves (56, 59, 61) operated under control and pulsed according to predetermined intervals and that the purge gas (60) is preferably introduced via a gas flow regulator (60).

17. :

Method as claimed in claim 9, characterized in that as the diaphragm measuring cell (8) a capacitive diaphragm measuring cell (8) or an optically readable diaphragm measuring cell (8), such as a Fabry-Perot arrangement, is utilized.

3. :

Method as claimed in claim, characterized in that at least for one, preferably for both, of the joining means (3, 6) a glass solder is utilized

18. :

Diaphragm vacuum measuring cell with a diaphragm (2) as pressure transducer, wherein on the one side of the diaphragm (2) at a spacing a first housing plate (1) is disposed sealing in the margin region with a joining means (3), such that between them a reference vacuum chamber (7) is formed and that on the other side of the diaphragm (2) at a spacing a second housing plate (4) is disposed sealing in the margin region with a joining means (3), such that between them a measuring vacuum chamber (9) is formed, and that the second housing plate (4) includes an opening and connection means (5) communicating with such and the measuring vacuum chamber (9) disposed sealing with joining means (3) for the connection of the measuring vacuum chamber (9) with the medium to be measured, wherein the diaphragm (2) and the two housing plates (1, 4) are comprised of ceramic, characterized in that the diaphragm is coated with an ALD method, such that the inner wall of the measuring vacuum chamber (9) and the opening with the connection means (5) is covered with a protective layer (13) such that the joining means (3, 6) are protectively covered.

19. :

Measuring cell as claimed in claim 18, characterized in that the metal oxide is one of the aluminum oxides, or that it preferably contains at least partially the sapphire form.

20. :

Measuring cell as claimed in claim 18, characterized in that at least one of the joining means (3, 6), preferably both, is comprised of a glass solder or a friction welding.

21. :

Measuring cell as claimed in claim 18, characterized in that the connection means (5) is formed of a metal or of a ceramic tubularly or as a connecting piece with a feed line, and that this is connected with the second housing plate with a joining means (6) through a glass solder or friction welding, wherein preferably the inner wall of the feed line of the connection means is also protectively covered

22. :

Measuring cell as claimed in claim 18, characterized in that the protective layer (13) is comprised of TiO₂ or Ta₂O₅.

23. :

Measuring cell as claimed in claim 18, characterized in that the protective layer (13) is comprised of Al₂O₃.

24. :

Measuring cell as claimed in claim 18, characterized in that the protective layer (13) within the measuring vacuum chamber (9) and the transition of the opening of the second housing plate (4) to the connection means (5) covers the joining means (3, 6) and takes place such, that at least in this region a protective layer thickness of 20 to 200 nm is provided, preferably in the range from 25 to 50 nm.

25. :

Measuring cell as claimed in claim 18, characterized in that with the contamination of the diaphragm measuring cell (8) by chlorine-containing process gases, a service life extension of the diaphragm measuring cell (8) is provided, which is greater by the factor 3, preferably by the factor 5 to 20, than without the protective coating (13).

26. :

Measuring cell as claimed in claim 18, characterized in that the diaphragm measuring cell (8) is a capacitive diaphragm measuring cell (8) or an optically readable diaphragm measuring cell (8) such as with a Fabry-Perot arrangement.