CMOS thermal-diffusivity temperature sensor based on polysilicon

Patent metadata

Field	Value
Publication number	US-10672964-B2
Application number	US-201615237281-A
Country	US
Kind code	B2
Filing date	Aug 15, 2016
Priority date	Aug 15, 2016
Publication date	Jun 2, 2020
Grant date	Jun 2, 2020

Abstract

The disclosed embodiments relate to the design of a temperature sensor, which is integrated into a semiconductor chip. This temperature sensor comprises an electro-thermal filter (ETF) integrated onto the semiconductor chip, wherein the ETF comprises: a heater; a thermopile, and a heat-transmission medium that couples the heater to the thermopile, wherein the heat-transmission medium comprises a polysilicon layer sandwiched between silicon dioxide layers. It also comprises a measurement circuit that measures a transfer function through the ETF to determine a temperature reading for the temperature sensor.

First claim

What is claimed is:

1. A temperature sensor, comprising:
a semiconductor chip;
an electro-thermal filter (ETF) integrated onto the semiconductor chip, wherein the ETF comprises,
a heater,
a thermopile, and
a heat-transmission medium that couples the heater to the thermopile, wherein the heat-transmission medium comprises a polysilicon layer sandwiched between silicon dioxide layers, wherein the thermopile comprises a sequence of alternating N+ and P+ segments of polysilicon having opposite temperature gradients, wherein the heater is implemented as a circular ring of P+ polysilicon, and wherein the heater is in the middle of the alternating N+ and P+ segments; and

a measurement circuit that measures a transfer function through the ETF to determine a temperature reading for the temperature sensor.

2. The temperature sensor of claim 1 , wherein the heater is comprised of polysilicon.

3. The temperature sensor of claim 1 , wherein the thermopile is comprised of polysilicon.

4. The temperature sensor of claim 3 , wherein the heater, the thermopile and the polysilicon layer in the heat-transmission medium are all implemented in a single polysilicon layer.

5. The temperature sensor of claim 1 , wherein the measurement circuit has a constant-frequency architecture that applies a constant frequency to the ETF and measures a resulting phase shift Φ ETF , which is translated into the temperature reading.

6. The temperature sensor of claim 5 , wherein the constant-frequency architecture uses sigma-delta modulation to measure the resulting phase shift Φ ETF .

7. The temperature sensor of claim 6 , wherein the constant-frequency architecture comprises:
a constant-frequency input that feeds into an input of the ETF and into the phase rotator;
the phase rotator with an input and an output;
a mixer that mixes an output of the ETF with the output of the phase rotator to produce a mixed signal;
an integrator that integrates the mixed signal to produce an integrated signal; and
an analog-to-digital converter (ADC) that converts the integrated signal into a digital output, which feeds into the input of the phase rotator.

8. The temperature sensor of claim 1 , wherein the measurement circuit has a constant-phase architecture that applies a constant phase shift to the ETF and measures a resulting frequency f ETF , which is translated into the temperature reading.

9. The temperature sensor of claim 8 , wherein the constant-phase architecture comprises:
a mixer that mixes an output of the ETF with a voltage-controlled oscillator (VCO) output signal to produced a mixed signal;
an integrator that integrates the mixed signal to produce an integrated signal; and
a voltage-controlled oscillator (VCO) that receives the integrated signal and produces the VCO output signal, which feeds into inputs of the ETF and the mixer.

10. A system, comprising:
a semiconductor chip with at least one processor;
at least one memory coupled to the at least one processor; and
an electro-thermal filter (ETF) integrated onto the semiconductor chip, wherein the ETF comprises,
a heater,
a thermopile, and
a heat-transmission medium that couples the heater to the thermopile, wherein the heat-transmission medium comprises a polysilicon layer sandwiched between silicon dioxide layers, wherein the thermopile comprises a sequence of alternating N+ and P+ segments of polysilicon having opposite temperature gradients wherein the heater is implemented as a circular ring of P+ polysilicon, and wherein the heater is in the middle of the alternating N+ and P+ segments; and

a measurement circuit integrated onto the semiconductor chip that measures a transfer function through the ETF to determine a temperature reading for the temperature sensor.

11. The system of claim 10 , wherein the heater and the thermopile are comprised of polysilicon.

12. The system of claim 11 , wherein the heater, the thermopile and the polysilicon layer in the heat-transmission medium are all implemented in a single polysilicon layer.

13. The system of claim 10 , wherein the measurement circuit has a constant-frequency architecture that applies a constant frequency to the ETF and measures a resulting phase shift Φ ETF , which is translated into the temperature reading.

14. The system of claim 13 , wherein the constant-frequency architecture uses sigma-delta modulation to measure the resulting phase shift Φ ETF .

15. The system of claim 14 , wherein the constant-frequency architecture comprises:
a constant-frequency input that feeds into an input of the ETF and into the phase rotator;
the phase rotator with an input and an output;
a mixer that mixes an output of the ETF with the output of the phase rotator to produce a mixed signal;
an integrator that integrates the mixed signal to produce an integrated signal; and
an analog-to-digital converter (ADC) that converts the integrated signal into a digital output, which feeds into the input of the phase rotator.

16. The system of claim 10 , wherein the measurement circuit has a constant-phase architecture that applies a constant phase shift to the ETF and measures a resulting frequency f ETF , which is translated into the temperature reading.

17. The system of claim 16 , wherein the constant-phase architecture comprises:
a mixer that mixes an output of the ETF with a voltage-controlled oscillator (VCO) output signal to produced a mixed signal;
an integrator that integrates the mixed signal to produce an integrated signal; and
a voltage-controlled oscillator (VCO) that receives the integrated signal and produces the VCO output signal, which feeds into inputs of the ETF and the mixer.

18. A method for sensing a temperature, comprising:
operating an electro-thermal filter (ETF) integrated onto a semiconductor chip, wherein the ETF comprises,
a heater,
a thermopile, and
a heat-transmission medium that couples the heater to the thermopile, wherein the heat-transmission medium comprises a polysilicon layer sandwiched between silicon dioxide layers, wherein the thermopile comprises a sequence of alternating N+ and P+ segments of polysilicon having opposite temperature gradients, wherein the heater is implemented as a circular ring of P+ polysilicon, and wherein the heater is in the middle of the alternating N+ and P+ segments; and

while the ETF is operating, using a measurement circuit to measure a transfer function through the ETF; and

using the measured transfer function to determine a temperature reading for the temperature sensor.

Assignees

• Oracle Int Corp

Inventors

• Saeedi Saman
• Liu Frankie Y
• Zhang Yue
• Yang Suwen

Classifications

• H01L35/32

  Electricity · mapped topic

• H01L35/12 Primary

  Electricity · mapped topic

• G01K7/028 Primary

  using microstructures, e.g. made of silicon · CPC title

• G01K7/42

  Circuits effecting compensation of thermal inertia; Circuits for predicting the stationary value of a temperature · CPC title

• H10N10/17

  characterised by the structure or configuration of the cell or thermocouple forming the device · CPC title