METHOD FOR PRODUCING A VACUUM MEASURING CELL OF THE MEMBRANE TYPE

• US 20100146771A1
• Filed: 03/25/2008
• Published: 06/17/2010
• Est. Priority Date: 04/07/2007
• Status: Active Grant

• Current Assignee: Inficon Holding AG
• Original Assignee: INFICON GmbH (Inficon Holding AG)
• Inventors: Bertsch, Dietmar, Onda, Nico, Dietrich, Klaus, Wüest, Martin
• Granted Patent: US 7,845,546 B2
• Time in Patent Office: Days
• US Class Current: 29/595
• CPC Class Codes: C04B 2235/3217 Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
• CPC Class Codes: C04B 2235/402 Aluminium
• CPC Class Codes: C04B 2235/6567 Treatment time
• CPC Class Codes: C04B 2237/121 based on aluminium
• CPC Class Codes: C04B 2237/122 based on refractory metals
• CPC Class Codes: C04B 2237/343 Alumina or aluminates
• CPC Class Codes: C04B 2237/52 Pre-treatment of the joining surfaces, e.g. cleaning, machining
• CPC Class Codes: C04B 2237/708 of one or more of the interlayers
• CPC Class Codes: C04B 2237/72 Forming laminates or joined articles comprising at least two interlayers directly next to each other
• CPC Class Codes: C04B 35/10 based on aluminium oxide
• CPC Class Codes: C04B 37/006 consisting of metals or metal salts
• CPC Class Codes: G01L 19/0627 Protection against aggressive medium in general
• CPC Class Codes: G01L 9/0044 Constructional details of non-semiconductive diaphragms
• 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
• CPC Class Codes: Y10T 29/49007 Indicating transducer

Abstract

Method for producing a vacuum measuring cell having a pressure transducer diaphragm with housing plates sealed on opposite sides to form reference and measuring vacuum chambers. An opening in one plate communicates with the measuring vacuum chamber and has a sealed connection for joining to medium to be measured. The diaphragm and plates are aluminum oxide ceramic and at least one of the seals is aluminum with a thickness of 0.5 μm to 30 μm. The ceramic parts are pressed together at increased temperature of 600° C. to 680° C. in a process gas atmosphere including a reducing gas, during a time of 30 to 90 minutes, and subsequently a tempering step is carried out in a second process gas atmosphere including oxygen, tempering taking place at a temperature of 450° C. to 575° C. such that the metallic aluminum is oxidized into aluminum oxide.

Claims

1. Method for the production of a vacuum measuring cell (8) with a diaphragm (2) as pressure transducer, wherein on the one side of the diaphragm (2) spaced apart is disposed a first housing plate (1) in the margin region with a joining means (3) forming a seal, such that between them a reference vacuum chamber (7) is formed, and that on the other side of the diaphragm (2) spaced apart a second housing plate (4) is disposed in the margin region with a joining means (3) forming a seal, such that between them a measuring vacuum chamber (9) is formed, and that the second housing plate (4) includes an opening and, communicating with such opening and the measuring vacuum chamber (9), connection means (5) with joining means (6) are disposed forming a seal for the joining of the measuring vacuum chamber (9) with the medium to be measured, wherein at least the diaphragm (2) and the two housing plates (1, 4) are realized as ceramic parts (1, 2, 4) of an aluminum oxide, characterized in that for at least one of the joining means (3, 6) aluminum with a thickness in the range from 0.5 μ

m to 30 μ

m is disposed in the joining region between the ceramic parts (1, 2, 4) to be joined, and that the ceramic parts (1, 2, 4) to be joined are pressed together at increased temperature in the range from 600°

C. to 680°

C. in a process gas atmosphere encompassing the parts, which atmosphere includes a reducing gas, during a time in the range from 30 to 90 minutes, and that subsequently a tempering step is carried out in a second process gas atmosphere which includes oxygen, wherein the tempering takes place in a temperature range from 450°

C. to 575°

C. such that the metallic aluminum is substantially oxidized to aluminum oxide.

2. Method as claimed in claim 1, characterized in that as the ceramic part one of the aluminum oxides of the form alpha or gamma is utilized, or that preferably at least partially the form sapphire is utilized, wherein the ceramic parts can also have different shaping.

3. Method as claimed in claim 1, characterized in that the surfaces to be joined of the ceramic parts (1, 2, 4) are produced with a mean surface roughness of less than 500 nm and that the surfaces to be joined are preferably planar.

4. Method as claimed in claim 1, characterized in that the time of the tempering is in the range from 2.0 to 12 hours, preferably 6.0 to 10 hours.

5. Method as claimed in claim 1, characterized in that at least the surfaces of the ceramic parts (1, 2, 4) to be joined are cleaned of foreign material before the joining process, preferably through chemical etching, plasma etching or ion etching.

6. Method as claimed in claim 5, characterized in that the chemical cleaning is carried out using a solution containing HNO₃ and preferably a further treatment step is carried out using a solution containing HF.

7. Method as claimed in claim 1, characterized in that ceramic parts (1, 2, 4) are utilized having a purity of better than 99%, preferably better than 99.5%.

8. Method as claimed in claim 1, characterized in that on at least one of the surfaces to be joined of the ceramic parts (1, 2, 4) an adhesion promoting metallic layer is deposited and this layer is preferably comprised of Ti or Cr.

9. Method as claimed in claim 1, characterized in that the joining means aluminum (3, 6) is deposited as a layer on at least one of the surfaces to be joined of the ceramic parts (1, 2, 4) to be joined, preferably using a vacuum process such as preferably sputtering.

10. Method as claimed in claim 9, characterized in that a layer thickness in the range from 0.2 μ

m to 15 μ

m, preferably in the range from 0.5 μ

m to 6.0 μ

m, is deposited.

11. Method as claimed in claim 1, characterized in that as the joining means (3, 6) a foil of aluminum is utilized with a thickness in the range from 10 μ

m to 50 μ

m, preferably in the range from 10 μ

m to 30 μ

m.

12. Method as claimed in claim 1, characterized in that the joining is set to a shearing strength in the range from 5 N/mm² to 35 N/mm², preferably in the range from 14 N/mm² to 42 N/mm².

13. Method as claimed in claim 1, characterized in that after the joining step, in a further step in the margin region of the joining (3, 6) and at least in the joining region an additional layer (13) is deposited as a vacuum tightening means, which covers and overlaps the joining region and at least one subregion of the joined ceramic parts (1, 2, 4).

14. Method as claimed in claim 13, characterized in that as a sealing means (13) is applied a glass solder or preferably a layer deposited using an ALD method.

15. Method as claimed in claim 13, characterized in that an additional covering (14) is applied for improved sealing with a material only in the joining region as additional sealing means (14), wherein such covering is only applied on the outer surface of the measuring cell (8) forming a seal, and that as the material (14) preferably a glass solder is utilized.

16. Method as claimed in claim 1, characterized in that the vacuum measuring cell (8) is realized as a capacitive diaphragm measuring cell (CDG).

17. Method as claimed in claim 1, characterized in that the vacuum measuring cell (8) is realized as an optically readable diaphragm measuring cell (ODG).