On-board microelectromechanical system (MEMS) sensing device for power semiconductors

• US 6,690,178 B2
• Filed: 10/26/2001
• Issued: 02/10/2004
• Est. Priority Date: 10/26/2001
• Status: Expired due to Fees

• Current Assignee: PS4 Luxco S.a.r.l.
• Original Assignee: Rockwell Automation Technologies Incorporated (Allen-Bradley Co., Inc.)
• Inventors: Kretschmann, Robert J., Harris, Richard D.
• Primary Examiner(s): Deb, Anjan K.
• Application Number:
  US10/039,731
• Publication Number:
  US 20030080754A1
• Time in Patent Office: 837 Days
• Field of Search: 324/649, 324/658, 324/661, 324/660, 324/99.R, 324/117.R, 324/522, 324/90, 324/768, 324/769, 324/109, 361/78, 310/309
• US Class Current: 324/649
• CPC Class Codes: G01R 15/148 involving the measuring of a magnetic field or electric field G01R15/18, G01R15/20, G01R15/24, G01R15/26 take precedence
• CPC Class Codes: G01R 31/2621 for testing field effect transistors, i.e. FET's
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• 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
• CPC Class Codes: H01L 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/10253 Silicon [Si]
• CPC Class Codes: H01L 2924/1305 Bipolar Junction Transistor [BJT]
• CPC Class Codes: H01L 2924/13055 Insulated gate bipolar transistor [IGBT]
• CPC Class Codes: H01L 2924/13091 Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• CPC Class Codes: H01L 2924/19041 being a capacitor

Abstract

An on-board micro-electromechanical (MEMS) isolator is provided on board a power semiconductor device for measuring voltage, current, or both. In particular, the power semiconductor may comprise a plurality of transistors connected in parallel, such that a MEMS isolator connected in parallel with one of the transistors measures voltage across the semiconductor. A MEMS isolator may further be connected in series with the transistors to measure current flow thereacross. A compensation circuitry may be provided to receive the current output from the isolator, and determine total current flow through the power semiconductor.

Claims

1. An on-board micro-electromechanical (MEMS) electrical device for sensing an electrical property of a power transistor having a collector, a base, and an emitter disposed on a support, the device comprising:

a substrate connected to the support;

an element supported by the substrate and movable between a first and second position;

an actuator attached to the element to receive an input electrical signal from the transistor that exerts a force dependent on the input electrical signal urging the element toward the second position;

a bias structure attached to the element to exert a predetermined opposite force on the element urging the element towards the first position; and

a sensor attached to the element to provide an output electrical signal indicating movement of the element between the first position and the second position.

2. The device as recited in claim 1, wherein the actuator is selected from the group consisting of:

an electrostatic motor, a Lorentz force motor, a piezoelectric motor, and a thermal-expansion motor.

3. The device as recited in claim 2, wherein the device is connected in series to the power transistor to measure current flow therethrough.

4. The device as recited in claim 3, wherein the power transistor further comprises a plurality of transistors connected in parallel, and wherein the device is connected in series to one of the plurality of transistors to measure current flowing therethrough.

5. The device as recited in claim 4, further comprising compensation circuitry mounted onto the substrate for determining or correcting total current flow through the power transistor.

6. The device as recited in claim 2, wherein the device is connected in parallel with the power transistor to measure voltage therethrough.

7. The device as recited in claim 6, wherein the power transistor further comprises a plurality of transistors connected in parallel, and wherein the device measures voltage across one of the plurality of transistors.

8. The device as recited in claim 1, wherein the bias structure is selected from the group consisting of:

an electrostatic motor, a Lorentz force motor, a piezoelectric motor, a thermal-expansion motor, and a mechanical-displacement motor.

9. The device as recited in claim 1, wherein the sensor is selected from the group consisting of:

a capacitive sensor, a piezoelectric sensor, a photoelectric sensor, a resistive sensor, and an optical switching sensor.

10. The device as recited in claim 1, wherein at least a portion of the element is electrically insulated so as to electrically isolate the first and second locations from each other.

11. The device as recited in claim 1, wherein the substrate is conductive.

12. The device as recited in claim 1, wherein the substrate is insulating.

13. A power semiconductor device having on-board sensing capabilities, the device comprising:

a plurality of power transistors electrically connected, wherein one of the power transistors is supported by a first substrate, and has a collector, a base, and an emitter;

a first MEMS device disposed on a second substrate that is connected to the first substrate, wherein the MEMS device is in electrical communication with said one of the power transistors, said MEMS sensor including;

i. an actuator attached to the element to receive an electrical input signal from said one of the power transistors;

ii. an element supported by the second substrate for movement between a first and second position with respect to the substrate dependent upon the electrical input signal;

iii. a bias structure attached to the element to exert a predetermined opposite force on the element urging the element toward the first position; and

iv. a sensor attached to the second portion of the element to provide an output electrical signal indicating movement of the element between the first position and the second position;

wherein an input signal of above a predetermined threshold overcomes the opposite force to cause the element to move rapidly from the first to the second position to produce the output electrical signal electrically isolated from the input electrical signal.

14. The semiconductor device as recited in claim 13, wherein the actuator is selected from the group consisting of:

an electrostatic motor, a Lorentz force motor, a piezoelectric motor, and a thermal-expansion motor.

15. The semiconductor device as recited in claim 14, wherein the MEMS device is connected in series to said one of the transistors to measure current flowing therethrough.

16. The semiconductor device as recited in claim 15, further comprising compensation circuitry mounted onto the substrate, receiving the current output from the sensor, and calculating and/or correcting total current flow through the power transistor.

17. The semiconductor device as recited in claim 13, wherein the MEMS device is connected in parallel to said one of the transistors to measure voltage there-across.

18. The semiconductor device as recited in claim 13, wherein the first MEMS device is connected to the power semiconductor device to measure voltage therethrough, further comprising a second MEMS device having the element, the actuator, the bias structure, and the sensor, wherein the second sensor, wherein the second MEMS device is connected to the semiconductor device to measure current flowing therethrough such that the electrical output signal is a current output.

19. The semiconductor device as recited in claim 18, wherein the first MEMS device is connected in parallel to said one of the plurality of transistors.

20. The semiconductor device as recited in claim 19, wherein the second MEMS device is connected in series to said one of the plurality of transistors.

21. The semiconductor device as recited in claim 20, further comprising compensation circuitry receiving the current output from the second MEMS device and determining a total current flow across the semiconductor device.

22. The semiconductor device as recited in claim 18, wherein the second MEMS device is connected to said one of the plurality of transistors.

23. The semiconductor device as recited in claim 13, wherein the substrate is insulating.

24. The semiconductor device as recited in claim 13, wherein the substrate is conductive.