초록 ▼

A semiconductor pressure sensor (720) includes a thin film piezoelectric element (701) which applies strain to a portion of a semiconductor substrate that corresponds to a thin region (402). The thin film piezoelectric element (701) is formed at a distance away from diffusion resistors (406, 408, 41

A semiconductor pressure sensor (720) includes a thin film piezoelectric element (701) which applies strain to a portion of a semiconductor substrate that corresponds to a thin region (402). The thin film piezoelectric element (701) is formed at a distance away from diffusion resistors (406, 408, 410, and 412) functioning as strain gauges and is extended to the proximity of a bonding pad (716A) connected to an upper electrode layer of the thin film piezoelectric element and a bonding pad (716F) connected to a lower electrode thereof. The diffusion resistors (406, 408, 410, and 412) constitute a bridge circuit by metal wiring (722) and diffusion wiring (724). During self-diagnosis, a prescribed voltage is applied to a thin film piezoelectric element (701). If the output difference of the bridge circuit between before and after the voltage application falls outside a prescribed range, it is determined that a breakage occurs in the semiconductor pressure sensor (720).

대표청구항 ▼

1. A semiconductor pressure sensor comprising: a semiconductor substrate having a thin region and a thick region provided to surround said thin region;at least one strain gauge resistor formed on one main surface of said semiconductor substrate and having a resistance value changing according to str

1. A semiconductor pressure sensor comprising: a semiconductor substrate having a thin region and a thick region provided to surround said thin region;at least one strain gauge resistor formed on one main surface of said semiconductor substrate and having a resistance value changing according to strain of a portion of said semiconductor substrate that corresponds to said thin region; andat least one thin film piezoelectric element formed in a region at least including part of said thin region on said semiconductor substrate, and having a lower electrode layer, a piezoelectric layer, and an upper electrode layer,wherein said at least one thin film piezoelectric element is formed in a region at a distance away from said at least one strain gauge resistor. 2. The semiconductor pressure sensor according to claim 1, wherein said at least one thin film piezoelectric element has an elongated shape having a longitudinal axis in a direction toward a central portion of said thin region. 3. The semiconductor pressure sensor according to claim 2, wherein said at least one thin film piezoelectric element is provided to extend across a boundary between said thin region and said thick region to reach said thick region. 4. The semiconductor pressure sensor according to claim 3, wherein said at least one thin film piezoelectric element is provided to further extend along an outer circumference of said thin region, in said thick region. 5. The semiconductor pressure sensor according to claim 3, wherein said at least one thin film piezoelectric element includes a plurality of thin film piezoelectric elements formed on said semiconductor substrate. 6. The semiconductor pressure sensor according to claim 5, wherein said plurality of thin film piezoelectric elements are coupled to each other on said thick region. 7. The semiconductor pressure sensor according to claim 5, wherein said plurality of thin film piezoelectric elements are extended to a central portion of said thin region and are coupled to each other at said central portion of said thin region. 8. The semiconductor pressure sensor according to claim 3, wherein said semiconductor pressure sensor further comprises a plurality of bonding pads provided on said thick region,said at least one thin film piezoelectric element is provided to extend to the proximity of at least one bonding pad of said plurality of bonding pads. 9. The semiconductor pressure sensor according to claim 8, wherein said plurality of bonding pads are provided side by side on one side of said semiconductor substrate. 10. The semiconductor pressure sensor according to claim 9, wherein said upper electrode layer and said lower electrode layer are connected to a first bonding pad located at a first end and a second bonding pad located at a second end, respectively, of said plurality of bonding pads provided side by side on said one side of said semiconductor substrate. 11. The semiconductor pressure sensor according to claim 1, wherein said semiconductor pressure sensor comprises four strain gauge resistors as said at least one strain gauge resistor,said thin region is approximately quadrilateral, andsaid four strain gauge resistors are each formed in proximity to a midpoint of each side of said thin region. 12. The semiconductor pressure sensor according to claim 11, wherein said at least one thin film piezoelectric element is formed on a diagonal line of said thin region. 13. The semiconductor pressure sensor according to claim 1, wherein said thin region is approximately circular. 14. The semiconductor pressure sensor according to claim 1, wherein said at least one strain gauge resistor is a diffusion resistor formed by diffusing an impurity in one main surface of said semiconductor substrate. 15. The semiconductor pressure sensor according to claim 1, wherein a main component of said piezoelectric layer is PZT. 16. The semiconductor pressure sensor according to claim 1, wherein said at least one strain gauge resistor is connected to wiring on said thin region, andsaid wiring includes diffusion wiring. 17. The semiconductor pressure sensor according to claim 1, wherein a thickness of said piezoelectric layer is 0.01 μm or more and 5 μm or less. 18. The semiconductor pressure sensor according to claim 1, wherein said semiconductor substrate is an SOI (Silicon on Insulator) substrate. 19. A method of manufacturing a semiconductor pressure sensor, comprising the steps of: preparing a semiconductor substrate having one main surface Si layer having a first conductivity type and the other main surface Si layer;forming a strain gauge resistor having a second conductivity type different from said first conductivity type, on said one main surface Si layer;forming diffusion wiring having said second conductivity type and having a higher impurity concentration than said strain gauge resistor, in a region adjacent to said strain gauge resistor in said one main surface Si layer;forming a first interlayer insulating film on said one main surface Si layer;forming a lower electrode layer on said first interlayer insulating film;forming a piezoelectric layer on said lower electrode layer;forming an upper electrode layer on said piezoelectric layer;forming a second interlayer insulating film on said first interlayer insulating film, said lower electrode layer, said piezoelectric layer, and said upper electrode layer;forming contact holes reaching said diffusion wiring, said lower electrode layer, and said upper electrode layer, in said second interlayer insulating film;forming metal wiring on said second interlayer insulating film and in said contact holes; andforming a reference pressure chamber in said other main surface Si layer. 20. The method of manufacturing a semiconductor pressure sensor according to claim 19, wherein the contact hole reaching said lower electrode layer and the contact hole reaching said upper electrode layer are formed at the same time.