Temperature control system for a thermal reactor

• US 6,207,937 B1
• Filed: 08/31/1999
• Issued: 03/27/2001
• Est. Priority Date: 05/11/1998
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Semitool Incorporated (Applied Materials Incorporated)
• Inventors: McHugh, Paul R., Tsakalis, Konstantinos, Stoddard, Kevin
• Primary Examiner(s): PASCHALL, MARK H
• Application Number:
  US09/386,567
• Time in Patent Office: 574 Days
• Field of Search: 219/494, 219/483, 219/486, 219/497, 219/501, 219/505, 219/507, 392/416, 374/110
• US Class Current: 219/497
• CPC Class Codes: C23C 16/52 Controlling or regulating the coating process C23C16/45557, C23C16/279 take precedence
• CPC Class Codes: C30B 25/10 Heating of the reaction chamber or the substrate
• CPC Class Codes: C30B 25/16 Controlling or regulating controlling or regulating in general G05
• CPC Class Codes: C30B 31/12 Heating of the reaction chamber
• CPC Class Codes: C30B 31/18 Controlling or regulating
• CPC Class Codes: F27B 9/024 with superimposed tracks
• CPC Class Codes: F27B 9/063 Resistor heating, e.g. with resistors also emitting IR rays
• CPC Class Codes: F27B 9/40 Arrangements of controlling or monitoring devices
• CPC Class Codes: F27D 19/00 Arrangements of controlling devices
• CPC Class Codes: F27D 21/0014 Devices for monitoring temperature
• CPC Class Codes: H01L 21/67109 mainly by convection
• CPC Class Codes: H01L 21/67248 Temperature monitoring

Abstract

A temperature control system for a thermal reactor is disclosed that addresses many of the problems in the art. In accordance with one aspect of the disclosed control system, a plurality of temperature controllers are employed. Each temperature controller employs one or more dynamic models that are optimized for a given temperature range. The temperature range over which a particular controller is optimized is preferably generally exclusive of the temperature ranges over which other controllers of the plurality of temperature controllers are optimized. In accordance with another aspect of the control system, the control system employs enhanced ramp trajectory logic. In accordance with another aspect of the control system, the control system employs a virtual temperature sensor in the event of a hardware failure of the corresponding non-virtual temperature sensor. Upon the detection of a failure of the non-virtual temperature sensor, the temperature control system automatically substitutes a virtual temperature sensor in its place as a control system input. In accordance with a still further aspect of the temperature control system, the control system is provided with control logic that switches the control mode of the system in the event of a failure of a heating element. All of the foregoing aspect of the present invention may be combined into a single temperature controller. Alternatively, these temperature control system improvements may be incorporated as individual elements, without reliance on the other inventive aspects disclosed herein.

Claims

1. A temperature control system for controlling the temperature of a thermal reactor, the temperature control system comprising:

a plurality temperature sensors disposed to measure temperature associated with the thermal reactor;

temperature sensor failure logic disposed to detect a failure of at least one of the plurality of temperature sensors;

a virtual temperature sensor model circuit having at least one output tracking at least one of the plurality of temperature sensors based on inputs received from other selected ones of the plurality of temperature sensors;

a controller responsive to the plurality of temperature sensors;

substitution logic circuit responsive to the detection of a failure of the at least one of the plurality of temperature sensors by the temperature sensor failure logic for substituting the at least one output of the virtual temperature sensor model circuit for the failed temperature sensor for input to the controller.

2. A temperature control system as set forth in claim 1 wherein the plurality of temperature sensors comprises thermocouples.

3. A temperature control system as set forth in claim 1 wherein the plurality of temperature sensors comprises profile sensors and spike sensors.

4. A temperature control system as set forth in claim 3 wherein the virtual temperature sensor model circuit models the profile sensors.

5. A temperature control system as set forth in claim 3 wherein the virtual temperature sensor model circuit models the profile sensors based on inputs from the spike sensors.