Granted Patent B2

US 8,947,098 · App. 13/051,430 · Granted Feb 3, 2015

Abstract

Claims (26)

1. An ionization gauge to measure pressure in a process, the ionization gauge comprising:

an electron source that emits electrons;

an anode that defines an ionization space;

a collector electrode to collect ions formed by an impact between the electrons and gas in the ionization space; and

a controller that actively varies emission current from the electron source to a substantially different control level, during operation of the ionization gauge to measure pressure in a measurement chamber, in response to a user defined operating parameter of a specific process as the specific process is being performed by a tool, other than the ionization gauge, exposed to the measured pressure.

2. The ionzation gauge of claim 1 , wherein the controller also controls emission current from the electron source as a function of pressure, in addition to controlling emission current in response to a user defined operating parameter.

3. The ionization gauge of claim 2 , wherein the controller controls the emission current in a continuously variable manner based on pressure.

4. The ionization gauge of claim 2 , wherein the function of pressure is selectable by a user.

5. The ionization gauge of claim 1 , wherein the operating parameter is a species of gas in the environment being measured.

6. The ionization gauge of claim 1 , wherein, in a first pressure range, collector current is held to a fixed level and, in a second pressure range, the collector current is allowed to vary.

7. The ionization gauge of claim 1 , further comprising plural emission current profiles stored in memory and selected by a user.

8. The ionization gauge of claim 1 , wherein a pressure signal is formed from the collected ions.

9. The ionization gauge of claim 1 , wherein the operating parameter is a control signal that anticipates a change in pressure due to a process step.

10. A method of measuring a gas pressure in a process, the method comprising the steps of:

producing electrons from an electron source;

during operation of an ionization gauge to measure pressure, dynamically varying an emission current from the electron source to a substantially different control level based on a user defined operating parameter of a specific process as the specific process is being performed by a tool, other than the ionization gauge, exposed to the measured pressure;

transmitting the electrons through an anode defining an ionization space of the ionization gauge to form ions; and

collecting the ions in the ionization gauge.

11. The method of claim 10 , further comprising controlling emission current from the electron source as a function of pressure, in addition to controlling emission current in response to a user defined operating parameter.

12. The method of claim 11 , wherein the emission current is varied in a continuously variable manner based on pressure.

13. The method of claim 11 , wherein the function of pressure is selected by a user.

14. The method of claim 10 , wherein the operating parameter is a species of gas in the environment being measured.

15. The method of claim 10 , wherein, in a first pressure range, collector current is held to a fixed level, and in a second pressure range, the collector current is allowed to vary.

16. The method of claim 10 , wherein the emission current is varied based on one of plural emission current profiles stored in memory and selected by a user.

17. The method of claim 10 , further comprising forming a pressure signal from the collected ions.

18. The method of claim 10 , wherein the operating parameter is a control signal that anticipates a change in pressure due to a process step.

Assignments (11)