Wide range pressure control using turbo pump

• US 20070079758A1
• Filed: 10/07/2005
• Published: 04/12/2007
• Est. Priority Date: 10/07/2005
• Status: Active Grant

• Current Assignee: Edwards Vacuum, LLC (Atlas Copco AB)
• Original Assignee: BOC Group Pty Limited (Linde Plc)
• Inventors: Holland, Peter, Wilson, Kate, Stephenson, Dawn
• Granted Patent: US 7,438,534 B2
• Time in Patent Office: Days
• US Class Current: 118/715
• CPC Class Codes: C23C 16/4412 Details relating to the exhausts, e.g. pumps, filters, scrubbers, particle traps
• CPC Class Codes: C23C 16/45557 Pulsed pressure or control pressure
• CPC Class Codes: F04D 19/042 Turbomolecular vacuum pumps
• CPC Class Codes: F04D 27/0253 by throttling F04D27/0246 takes precedence

Abstract

The present invention is an apparatus and method for controlling a process flow rate and a pressure in a vacuum process chamber that is evacuated by a turbomolecular pump. A throttle valve between the pump and the process chamber is controlled to regulate the pressure and flow rate. A backing valve downstream of the pump is also controlled to maintain the setting of the throttle valve within a preferred, stable operating range.

Claims

1. An apparatus for exhausting gas from an exhaust port of a vacuum chamber to maintain a process pressure in the chamber, comprising:

a pressure sensor for measuring pressure in the vacuum chamber;

a throttle valve in communication with the exhaust port of the vacuum chamber for regulating flow from the exhaust port;

a high-vacuum pump having a pump inlet and a backing port, the pump inlet communicating with the throttle valve;

a backing valve in communication with the pump backing port for regulating flow from the backing port; and

at least one controller for regulating opening sizes of the throttle valve and the backing valve based on a measurement from the pressure sensor, to maintain the process pressure in the chamber.

2. The apparatus of claim 1, wherein the at least one controller comprises at least one processor having an input from the pressure sensor for receiving the pressure measurement, and outputs to the backing valve and throttle valve for sending opening size regulation signals.

3. The apparatus of claim 1, wherein the at least one controller comprises:

a tool controller connected to the pressure sensor for sequencing the process chamber through at least one process flow rate and process pressure;

a throttle valve controller connected to the throttle valve for controlling an opening of the throttle valve;

a backing valve controller connected to the backing valve for controlling an opening of the backing valve; and

a processor in communication with the tool controller, the throttle valve controller and the backing valve controller, the processor having storage media for storing computer readable instructions executable by the processor for regulating opening sizes of the throttle valve and the backing valve based on a measurement from the pressure sensor, to maintain the at least one process flow rate and process pressure in the chamber.

4. The apparatus of claim 1, wherein the pressure sensor is a capacitance manometer.

5. The apparatus of claim 1, wherein the backing valve is a butterfly valve.

6. The apparatus of claim 1, wherein the throttle valve is a pendulum gate valve.

7. The apparatus of claim 1, wherein the throttle valve further comprises a stepping motor positioning device.

8. The apparatus of claim 1, wherein the throttle valve is controllable to a finite number of discrete opening sizes, and wherein the controller is further for regulating the opening size of the backing valve to achieve a process pressure in the chamber that is between those process pressures resulting from two adjacent discrete throttle valve opening sizes.

9. The apparatus of claim 1, wherein the process flow rate and the process pressure in the chamber are maintained without changing a rotational speed of the high-vacuum pump.

10. A method for controlling a process pressure in a vacuum chamber by regulating exhaust gas flowing from an exhaust port of the vacuum chamber and through a turbomolecular pump, the method comprising the steps of:

reading a pressure in the vacuum chamber;

controlling an opening of a throttle valve to regulate flow from the exhaust port to the turbomolecular pump based at least in part on the pressure reading, the throttle valve opening having a preferred operating range; and

controlling a backing valve downstream of the turbomolecular pump to maintain the throttle valve opening within the preferred operating range.

11. The method of claim 10, further comprising the step of:

reading computer executable instructions from a storage media, the instructions being for performing at least a portion of the method.

12. The method of claim 10, wherein the step of reading the pressure comprises reading a signal received from a capacitance manometer.

13. The method of claim 10, wherein the step of controlling a backing valve comprises rotating a butterfly valve.

14. The method of claim 10, wherein the step of controlling the opening of the throttle valve comprises advancing and retracting a pendulum gate valve.

15. The method of claim 10, wherein the step of controlling the opening of the throttle valve comprises actuating a stepping motor positioning device.

16. The method of claim 10, wherein the throttle valve is controllable to a finite number of discrete opening sizes, and wherein the step of controlling the backing valve comprises regulating the opening size of the backing valve to achieve a process pressure in the chamber that is between those process pressures resulting from two adjacent discrete throttle valve opening sizes.

17. The method of claim 10, wherein the process flow rate and the process pressure in the chamber are controlled without changing a rotational speed of the turbopump.

18. A method for exhausting gas from an exhaust port of a vacuum chamber and through a turbomolecular pump, to maintain a process pressure in the chamber, the method comprising the steps of:

measuring a pressure in the vacuum chamber;

regulating an opening size of a throttle valve in communication between the exhaust port of the vacuum chamber and the turbomolecular pump;

regulating an opening size of a backing valve in communication with a backing port of the pump for regulating a compression ratio of the pump;

whereby regulating the opening sizes of the throttle valve and the backing valve maintain the process pressure in the chamber.

19. The method of claim 18, wherein the throttle valve is controllable to a finite number of discrete opening sizes, and wherein the step of regulating the backing valve further comprises regulating the opening size of the backing valve to achieve a process pressure in the chamber that is between those process pressures resulting from two adjacent discrete throttle valve opening sizes.