# US 2014/0152320 A1 · Ionization gauge with operational parameters and geometry designed for high pressure operation

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- Number: US 2014/0152320 A1
- Document ID: US20140152320A1
- Status: Published application
- Kind: A1
- Application number: 14/174,386
- Filed: 2014-02-06
- Published: 2014-06-05
- Earliest claimed: 2008-02-21
- Assignees: Brooks Automation, Inc.
- Applicants: Brooks Automation, Inc.
- Inventors: Gerardo A. Brucker
- Web page: https://patentgrep.com/patent/US20140152320A1

## CPC

- G01L 21/30: by making use of ionisation effects
- G01L 21/32: using electric discharge tubes with thermionic cathodes
- G01L 21/34: using electric discharge tubes with cold cathodes
- H01J 41/02: Discharge tubes for measuring pressure of introduced gas {or for detecting presence of gas}
- G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G)
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

An ionization gauge to measure pressure and to reduce sputtering yields includes at least one electron source that generates electrons. The ionization gauge also includes a collector electrode that collects ions formed by the collisions between the electrons and gas molecules. The ionization gauge also includes an anode. An anode bias voltage relative to a bias voltage of a collector electrode is configured to switch at a predetermined pressure to decrease a yield of sputtering collisions.

## Claims

### Claim 1

A process comprising:
providing a substrate;
evacuating a tool to perform processes on the substrate in the tool;
measuring pressure by providing:
at least one electron source that generates electrons;
a collector electrode that collects ions formed by the impact between the electrons and gas molecules; and
an anode configured to switch a bias voltage relative to a bias voltage of the collector electrode based on a predetermined pressure; and
conducting operations on the substrate in the vacuum environment to form a processed substrate.

### Claim 2 (depends on 1)

The process of claim 1, wherein the anode is configured to switch the bias voltage relative to the bias voltage of the collector electrode based on the predetermined pressure to decrease a yield of sputtering collisions.

### Claim 3 (depends on 1)

The method of claim 1, further comprising switching the bias voltage so a potential difference between the anode and the collector electrode is less than about 90 volts.

### Claim 4 (depends on 1)

The method of claim 1, further comprising operating the electron source at less than about 20 volts.

### Claim 5

A process comprising:
measuring a parameter of the process using an analytical tool; and
measuring pressure by providing:
at least one electron source that generates electrons;
a collector electrode that collects ions formed by the impact between the electrons and gas molecules; and
an anode configured to switch a bias voltage relative to a bias voltage of the collector electrode based on a predetermined pressure.

### Claim 6 (depends on 5)

The process of claim 5, wherein the anode is configured to switch the bias voltage relative to the bias voltage of the collector electrode based on the predetermined pressure to decrease a yield of sputtering collisions.

### Claim 7

An ionization gauge to measure pressure comprising:
at least one electron source that generates electrons; and
an anode that defines an ionization volume therein;
at least one collector electrode located outside of the anode that collects ions formed by the impact between the electrons and gas molecules.

### Claim 8 (depends on 7)

The ionization gauge of claim 7, further comprising:
a second collector electrode being positioned inside the anode.

### Claim 9 (depends on 7)

The ionization gauge of claim 7, wherein the bias voltage of the anode is switched relative to the bias voltage of the collector electrode to decrease a yield of sputtering collisions.

### Claim 10

A method of measuring a gas pressure from gas molecules and atoms, comprising the steps of:
producing electrons from at least one electron source;
transmitting the electrons to an anode to form ions in an ionization volume within the anode; and
collecting ions formed by impact between the electrons and the gas molecules and atoms by collecting ions located outside of the anode.

### Claim 11 (depends on 10)

The method of claim 10, comprising collecting ions located inside the anode.

### Claim 12 (depends on 10)

The method of claim 10, wherein ions are collected out side of the anode at pressures above about 10−4 Torr.