Method and apparatus for thin metal film thickness measurement

• US 7,204,639 B1
• Filed: 09/26/2003
• Issued: 04/17/2007
• Est. Priority Date: 09/26/2003
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Korolik, Mikhail, Gotkis, Yehiel
• Primary Examiner(s): Verbitsky; Gail
• Assistant Examiner(s): Jagan; Mirellys
• Application Number:
  US10/672,019
• Time in Patent Office: 1,299 Days
• Field of Search: 374/5, 374/6, 374/7, 374/121, 374/141, 374/131, 374/45, 374/57, 451/5, 451/6, 451/7, 451/8, 451/41, 356/630
• US Class Current: 374/7
• CPC Class Codes: G01B 21/085 using thermal means

Abstract

A method for measuring a metal film thickness is provided. The method initiates with heating a region of interest of a metal film with a defined amount of heat energy. Then, a temperature of the metal film is measured. Next, a thickness of the metal film is calculated based upon the temperature and the defined amount of heat energy. A chemical mechanical planarization system capable of detecting a thin metal film through the detection of heat transfer dynamics is also provided.

Claims

1. A chemical mechanical planarization (CMP) system, comprising:

a wafer carrier configured to support a wafer during a planarization process;

an impulse heater configured to deliver a single defined heat energy pulse to a metal layer disposed on the wafer;

a sensor embedded in the wafer carrier, the sensor configured to detect heat energy emanating from a location on the metal layer due to the heat energy pulse, the sensor located to minimize reception of a reflected heat energy pulse from the defined heat energy pulse, the sensor is positioned to detect the heat energy emanating from a location on the metal layer that is different from where the impulse heater delivers the defined heat energy pulse to the metal layer; and

a computing device in communication with the sensor, the computing device configured to calculate a thickness of the metal layer based upon the detected heat energy in relation to the defined heat energy pulse.

2. The system of claim 1, wherein the sensor is an infrared sensor.

3. The system of claim 1, wherein the heat energy is infrared heat energy.

4. The system of claim 1, wherein the computing device includes a storage device storing a calibration curve relating the heat energy pulse and the detected heat energy to the thickness.

5. The system of claim 1, wherein the computing device is configured to calculate a heat transfer rate from values associated with the detected energy and the defined heat energy pulse.

6. The system of claim 1, wherein an axis of the impulse heater is different from an axis of the sensor.

7. The system of claim 1, wherein the computing device includes,

delay circuitry for delaying detection of the heat energy for a period of time after delivering the defined heat energy pulse.

8. A system for detecting a thickness of a metal layer during a chemical mechanical planarization process without contacting the metal layer, comprising:

an infrared impulse heater configured to deliver a single defined heat energy pulse to a metal layer disposed on a wafer;

an infrared sensor configured to detect heat energy emanating from a location on the metal layer caused by the heat energy pulse, such that the sensor is positioned to substantially eliminate reception of a reflected heat energy pulse from the defined heat energy pulse, the location on the metal layer that the sensor detects the heat energy emanating from being different from a location where the impulse heater delivers the defined heat energy pulse to the metal layer; and

a computing device in communication with the sensor, the computing device configured to calculate a thickness of the metal layer based upon the detected heat energy in relation to the defined heat energy pulse.

9. The system of claim 8, wherein an axis of the sensor and an axis of the impulse heater are substantially orthogonal to a top surface of the metal layer.

10. The system of claim 8, wherein the computing device includes,

delay circuitry for delaying detection of the detected heat energy for a period of time after delivering the defined heat energy pulse.