Valve-cell vacuum deposition apparatus including a leak detection device and method for detecting a leak in a vacuum deposition apparatus
The leak detection device is adapted to test the tightness of an inner tank ( 24 ) of a valve cell ( 20 ) of the vacuum deposition apparatus, either at its filling flange ( 25 ) or at its inner tank valve ( 28 ). A vacuum deposition apparatus equipped with a helium detector ( 51 ) mounted as a by-pass of the output of a high-flow-rate turbomolecular pump ( 42 ) which is connected to the vacuum deposition chamber ( 30 ) of the vacuum deposition apparatus by a slide gate valve ( 43 ). A valve-cell vacuum deposition apparatus equipped with a helium-based leak detection device including gas injection elements ( 52, 53 ) adapted to inject a gaseous mixture into the outer enclosure, the gaseous mixture being consisted of pure helium and an inert gas, and a method for detecting a leak in a valve-cell vacuum deposition apparatus are also described.
1. A valve-cell vacuum deposition apparatus ( 10 ; 200 ; 300 ) including:
at least one valve cell ( 20 ; 220 ; 320 ) comprising:
an outer enclosure ( 21 ),
an inner tank ( 24 ; 224 ), located inside the outer enclosure ( 21 ) and adapted to contain a material to be evaporated ( 26 ),
an inner tank valve ( 28 ; 228 ) comprising a valve input port ( 28 A; 228 A) in fluidic communication with the inner tank ( 24 ; 224 ) and a valve output port ( 28 B; 228 B),
a vacuum deposition chamber ( 30 ),
a transfer tube ( 11 ) comprising a tube input port ( 11 A) and connected to the valve output port ( 28 B; 228 B) of the inner tank valve ( 28 ; 228 ) and a tube output port ( 11 B), in such a manner that the tube output port ( 11 B) is located inside the vacuum deposition chamber ( 30 ), the tube output port ( 11 B) including an injector ( 12 ) adapted to generate a jet of vapour of the material to be evaporated ( 26 ) inside the vacuum deposition chamber ( 30 ), the vacuum deposition chamber ( 30 ) being connected to the outer enclosure ( 21 ) by means of a connecting flange ( 13 ), and
pumping means ( 40 ) adapted to evacuate the inside of the vacuum deposition chamber ( 30 ), the pumping means comprising:
a primary pump ( 41 ) having a primary pump input ( 41 A) and a primary pump output ( 41 B), and
a secondary pump ( 42 ) having a secondary pump input ( 42 A) and a secondary pump output ( 42 B), the secondary pump output ( 42 B) being connected to the primary pump input ( 41 A),
characterized in that it includes a leak detection device ( 50 ) comprising:
gas injection means ( 52 , 53 ) adapted to introduce helium in the vacuum deposition chamber ( 30 ),
gas pumping means adapted to pump the helium present in the vacuum deposition chamber ( 30 ),
a helium detector ( 51 ) comprising a detector input ( 51 A), the helium detector ( 51 ) delivering a signal representative of the helium flow rate through it,
pressure measuring means ( 54 , 54 A) adapted to measure the pressure inside the vacuum deposition chamber ( 30 ), and
signal processing means ( 55 ) adapted to process the signal relating to the helium flow rate delivered by the helium detector ( 51 ) and the signal delivered by the pressure measuring means ( 54 , 54 A), to deliver a signal representative of the leak rate of the inner tank valve ( 28 ; 228 ), and in that the pumping means ( 40 ) also include:
a secondary pump valve ( 43 ) placed between the vacuum deposition chamber ( 30 ) and the secondary pump input ( 42 A),
a primary pump valve ( 44 ) placed between the secondary pump output ( 42 B) and the primary pump input ( 41 A), and
a by-pass valve ( 45 ) placed between the secondary pump output ( 42 B) and the detector input ( 51 A), the by-pass being made upstream the primary pump valve ( 44 ).
2. The vacuum deposition apparatus ( 10 ; 300 ) according to claim 1 , wherein the inner tank valve ( 28 ) is located inside the outer enclosure ( 21 ), with its valve input port ( 28 A) connected to the inner tank ( 24 ).
3. The vacuum deposition apparatus ( 10 ; 300 ) according to claim 1 , wherein the tube input port ( 11 A) of the transfer tube ( 11 ) is located inside the outer enclosure ( 21 ), with the transfer tube ( 11 ) going through a first wall ( 21 A) of the outer enclosure ( 21 ) and a second wall ( 30 A) of the vacuum deposition chamber ( 30 ).
4. The vacuum deposition apparatus ( 10 ) according to claim 1 , wherein the pressure measuring means ( 54 , 54 A) deliver a signal representative of the pressure inside the inner tank ( 24 ).
5. The vacuum deposition apparatus ( 10 ) according to claim 1 , wherein the outer enclosure ( 21 ) is in fluidic communication with the vacuum deposition chamber ( 30 ).
6. The vacuum deposition apparatus ( 10 ; 200 ; 300 ) according to claim 1 , wherein the secondary pump ( 42 ) is a turbomolecular pump.
7. The vacuum deposition apparatus ( 10 ; 200 ; 300 ) according to claim 1 , wherein the secondary pump valve ( 43 ) is a slide gate valve.
8. The vacuum deposition apparatus according to claim 1 , wherein the secondary pump valve is a butterfly valve or a pendulous valve.
9. The vacuum deposition apparatus ( 10 ; 200 ; 300 ) according to claim 1 , wherein the gas injection means ( 52 , 53 ) of the leak detection device ( 50 ) are also adapted to introduce an inert gas in the vacuum deposition chamber ( 30 ), the inert gas forming a gaseous mixture with helium.
10. The vacuum deposition apparatus ( 10 ; 200 ; 300 ) according to claim 1 , wherein the leak detection device ( 50 ) also comprises piloting means ( 57 ) adapted to control the gas injection means ( 52 , 53 ) and the opening and closing of the inner tank valve ( 28 ; 228 ), the secondary pump valve ( 43 ), the primary pump valve ( 44 ) and the by-pass valve ( 45 ).
11. The vacuum deposition apparatus ( 10 ) according to claim 1 , wherein the signal processing means ( 55 ) deliver a signal representative of the leak rate of the inner tank valve ( 28 ) and the inner tank ( 24 ).
12. The vacuum deposition apparatus ( 10 ; 300 ) according to claim 11 , wherein the inner tank valve ( 28 ) is located inside the outer enclosure ( 21 ), with its valve input port ( 28 A) connected to the inner tank ( 24 ).
13. The vacuum deposition apparatus ( 10 ; 300 ) according to claim 11 , wherein the tube input port ( 11 A) of the transfer tube ( 11 ) is located inside the outer enclosure ( 21 ), with the transfer tube ( 11 ) going through a first wall ( 21 A) of the outer enclosure ( 21 ) and a second wall ( 30 A) of the vacuum deposition chamber ( 30 ).
14. The vacuum deposition apparatus ( 200 ; 300 ) according to claim 1 , wherein there are provided isolation means ( 228 ; 311 C) adapted to isolate the outer enclosure ( 21 ) from the vacuum deposition chamber ( 30 ).
15. The vacuum deposition apparatus ( 200 ) according to claim 14 , wherein the isolation means comprise the inner tank valve ( 228 ).
16. The vacuum deposition apparatus ( 300 ) according to claim 14 , wherein the isolation means comprise a weld ( 311 C) between the outer enclosure ( 21 ) and the transfer tube ( 11 ).
17. A method for detecting a leak in a valve-cell vacuum deposition apparatus ( 10 ) by deducing a leak rate, the vacuum deposition apparatus ( 10 ) including:
at least one valve cell ( 20 ) comprising:
an outer enclosure ( 21 ),
an inner tank ( 24 ; 224 ), located inside the outer enclosure ( 21 ), wherein the inner tank ( 24 ; 224 ) contains a material to be evaporated ( 26 ),
an inner tank valve ( 28 ; 228 ) comprising a valve input port ( 28 A; 228 A) in fluidic communication with the inner tank ( 24 ; 224 ) and a valve output port ( 28 B; 228 B),
a vacuum deposition chamber ( 30 ), and
a leak detection device ( 50 ),
the leak detection method being characterized in that it includes:
an initialization step wherein:
the inside of the vacuum deposition chamber ( 30 ) is evacuated, and
an initial leak flow rate in the vacuum deposition chamber ( 30 ) is measured by means of the leak detection device ( 50 ), and
a measurement step wherein:
the inner tank valve ( 28 ; 228 ) is opened to place the vacuum deposition chamber ( 30 ) in fluidic communication with the inner tank ( 24 ; 224 ), and
a gaseous mixture is injected in the vacuum deposition chamber ( 30 ), and
a pressure P 0 inside the inner tank ( 24 ; 224 ) is measured, and
the inner tank valve ( 28 ; 228 ) is closed, and
the inside of the vacuum deposition chamber ( 30 ) is evacuated down to a predetermined pressure in the vacuum deposition chamber ( 30 ), and
the vacuum deposition chamber ( 30 ) is placed in communication with the leak detection device ( 50 ), and
a final leak flow rate in the vacuum deposition chamber ( 30 ) is measured by means of the leak detection device ( 50 ), and
a leak rate of the inner tank valve ( 28 ; 228 ) is deduced from the final leak flow rate and the initial leak flow rate.
18. The leak detection method according to claim 17 , wherein the inner tank valve ( 28 ) of the vacuum deposition apparatus ( 10 ; 300 ) is located inside the outer enclosure ( 21 ), with its valve input port ( 28 A) connected to the inner tank ( 24 ).
19. The leak detection method according to claim 17 , wherein, at the end of the measurement step, the leak rate of the inner tank valve ( 28 ; 228 ) and the inner tank ( 24 ; 224 ) is deduced.
20. The leak detection method according to claim 19 , wherein the inner tank valve ( 28 ) of the vacuum deposition apparatus ( 10 ; 300 ) is located inside the outer enclosure ( 21 ), with its valve input port ( 28 A) connected to the inner tank ( 24 ).