Wafer to measure pressure at a number of points in a process chamber

• US 6,378,378 B1
• Filed: 05/02/2001
• Issued: 04/30/2002
• Est. Priority Date: 08/10/1998
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Fisher, Paul
• Primary Examiner(s): OEN, WILLIAM L
• Application Number:
  US09/847,974
• Time in Patent Office: 363 Days
• Field of Search: 737/06, 737/15, 737/18--27, 737/54, 29/254.1, 29/254.2, 296/211
• US Class Current: 73/754
• CPC Class Codes: C23C 16/45557 Pulsed pressure or control pressure
• CPC Class Codes: C23C 16/52 Controlling or regulating the coating process C23C16/45557, C23C16/279 take precedence
• CPC Class Codes: G01L 15/00 Devices or apparatus for measuring two or more fluid pressure values simultaneously
• CPC Class Codes: G01L 19/146 using flexible element between the transducer and the support
• CPC Class Codes: G01L 9/0042 Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms details about the integration or bonding of piezoresistor in or on the diaphragm G01L9/0052 and G01L9/0057 respectively
• CPC Class Codes: G01L 9/0054 integral with a semiconducting diaphragm
• CPC Class Codes: H01L 21/67253 Process monitoring, e.g. flow or thickness monitoring
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details

Abstract

A device for measuring pressure at several locations in a processing chamber under dynamic Conditions, i.e. when gas is flowing into and/or out of the chamber. A substrate has a plurality of pressure sensors electrically coupled to a measurement instrument. Conditions are established within a processing chamber to determine the effects of various process parameters, such as gas flow, on local pressures, and the local pressures are measured. The test conditions may simulate a process or may be standard test conditions to evaluate chamber configurations or hardware. The pressure test substrate may be calibrated under static conditions to improve the accuracy of the pressure readings.

Claims

1. A method for fabricating an integrated pressure sensor wafer, the method comprising:

(a) forming a cavity in a surface of a substrate, the cavity having ledges proximate to a perimeter of the cavity;

(b) filling the cavity with a sacrificial material;

(c) forming a layer of a first material over the sacrificial material;

(d) opening a plurality of release windows in the layer opposite the ledges of the cavity;

(e) releasing the sacrificial material;

(f) sealing the release windows by substantially filling the release windows with a second material to form a sealed cavity and a diaphragm of at least the first material;

(g) forming a thin-film resistor on the diaphragm; and

(h) forming a conductive trace on the surface of the substrate, the conductive trace being electrically coupled to the thin-film resistor.

2. The method of claim 1 wherein the sacrificial material comprises phosphosilicate glass and the first material comprises silicon.

3. The method of claim 1 wherein the conductive trace comprises a high-temperature conductor.

8. The method of claim 1 wherein the substrate comprises silicon.

9. The method of claim 1 further comprising:

planarizing the sacrificial material after (b).

10. The method of claim 1 wherein (g) forming the thin-film resistor comprises forming a Wheatstone bridge on the diaphragm.

11. The method of claim 1 wherein the sacrificial material comprises an organic material.

12. The method of claim 1 wherein (e) releasing the sacrificial material comprises using etching the sacrificial material.

4. A method for measuring pressures within a processing chamber using a pressure test wafer, the method comprising:

(a) placing the pressure test wafer in the processing chamber, the pressure test wafer being electrically coupled to a measurement instrument;

(b) establishing a selected gas flow rate to create local pressures on the pressure test wafer;

(c) measuring an electric signal from the pressure test wafer; and

(d) correlating the electric signal from the pressure test wafer to a pressure.

5. The method of claim 4 firer comprising, after (a), of heating the pressure test wafer to above about 150°

C.

6. The method of claim 4 further comprising, after (a), of heating the pressure test wafer to above about 450°

C.

7. The method of claim 4 further comprising correlating the pressure to a location on the pressure test wafer.

13. The method of claim 4 wherein the pressure test wafer comprises an array of pressure sensors.

14. The method of claim 4 wherein (d) correlating comprises correlating the electrical signal with calibration data.

15. The method of claim 4 wherein the test wafer comprises silicon.