Closed loop temperature controlled circuit to improve device stability
View Patent ↗An integrated circuit is provided having an active circuit. A heating element is adjacent to the active circuit and configured to heat the active circuit. A temperature sensor is also adjacent to the active circuit and configured to measure a temperature of the active circuit. A temperature controller is coupled to the active circuit and configured to receive a temperature signal from the temperature sensor. The temperature controller operates the heating element to heat the active circuit to maintain the temperature of the active circuit in a selected temperature range.
1. A device comprising:
a semiconductor substrate having an active region;
an active circuit in the active region;
a demand monitoring circuit coupled to the active circuit;
a temperature sensor in the active region adjacent to the active circuit, the temperature sensor being configured to measure a temperature of the active circuit;
a heating element adjacent to the active circuit and configured to heat the active circuit; and
a temperature controller coupled to the temperature sensor, the heating element, and the demand monitoring circuit, the temperature controller having a control signal output based on both temperature data from the temperature sensor and active circuit use data from the demand monitoring circuit, the control signal output coupled to the heating element to maintain the temperature of the active circuit above a threshold temperature.
2. The device of claim 1 wherein the heating element is a thin film heating element.
3. The device of claim 2 wherein the heating element is TaAl.
4. The device of claim 2 comprising a multilayer dielectric stack on a surface of the semiconductor substrate, the thin film heating element being located in the multilayer dielectric stack.
5. The device of claim 2 wherein the heating element is located above the active circuit.
6. The device of claim 2 wherein the heating element is on a surface of the semiconductor substrate, adjacent to the active circuit.
7. The device of claim 1 wherein the temperature sensor is a bandgap temperature sensor.
8. A method comprising:
generating, in a temperature sensor positioned in a semiconductor substrate of an integrated circuit, a temperature signal representative of a temperature of an active circuit in the semiconductor substrate;
receiving the temperature signal in a temperature controller;
receiving a use demand signal representative of the momentary demand on the active circuit;
heating the active circuit above a minimum threshold temperature, the heating including operating a heating element coupled to the integrated circuit to heat the active circuit above the minimum threshold temperature, the minimum threshold temperature being greater than 50° C.; and
maintaining the temperature of the active circuit above the minimum threshold temperature, the maintaining including varying a heat output of the heating element according to the temperature signal and the use demand signal to maintain the temperature of the active circuit above the minimum threshold temperature.
9. The method of claim 8 wherein maintaining includes varying the heat output of the heating element to maintain the temperature of the integrated circuit above the minimum threshold temperature and below a maximum threshold temperature.
10. The method of claim 9 wherein the heating element is a thin film heating element located in a dielectric stack of the integrated circuit.
11. The method of claim 10 wherein the heating includes sending a current through the thin film heating element to heat the integrated circuit.
12. The method of claim 11 wherein the maintaining includes varying a magnitude of the current to maintain the temperature above the minimum threshold temperature and below the maximum threshold temperature.
13. A device, comprising:
a semiconductor substrate;
an active circuit in the semiconductor substrate;
a temperature sensor positioned in the semiconductor substrate approximately adjacent to the active circuit, the temperature sensor having a temperature output signal representative of a temperature of the active circuit;
a demand monitoring circuit having a use output signal representative of a use demand of the active circuit;
a heating element positioned in the semiconductor substrate approximately adjacent to the active circuit; and
a temperature controller coupled to the temperature output, the use output, and the heating element, the temperature controller configured to maintain a substantially constant temperature in the active circuit by controlling the heating element based on both the temperature output signal and an expected heat output from use of the active circuit based on the use demand output signal.
14. The device of claim 13 , wherein the substantially constant temperature is above the operating temperature of the circuit during maximum use.
15. The device of claim 13 , wherein the heating element is a single heating element with a variable heat output.
16. The device of claim 13 , wherein the heating element is a plurality of heating elements, and the temperature controller selectively enables a number of the heating elements based on both the temperature output and the use output.