Semiconductor pressure sensor

Abstract

A semiconductor pressure sensor includes n-type semiconductor regions, which are formed in a diaphragm of a semiconductor substrate, piezoresistive elements, which are respectively formed in the n-type semiconductor regions, and conductive shielding thin film layers, which are respectively formed on the piezoresistive elements through an insulating thin film layer, and the piezoresistive elements form a Wheatstone bridge circuit. Further, the n-type semiconductor regions and the conductive shielding thin film layers are electrically connected to each other through contacts formed in the diaphragm.

What is claimed is: 
     
       1. A semiconductor pressure sensor comprising:
 a semiconductor substrate; 
 a diaphragm formed by thinning a portion of the semiconductor substrate, the diaphragm serving as a pressure receiving portion; and  
 n-type semiconductor regions formed in the diaphragm; 
 piezoresistive elements a first, a second, a third, and a fourth detecting portions, which are respectively formed in the n-type semiconductor regions diaphragm; and 
 conductive shielding thin film layers, which are respectively formed on the piezoresistive elements through an insulating thin film layer, the piezoresistive elements forming a Wheatstone bridge circuit, 
 wherein the n-type semiconductor regions and the conductive shielding thin film layers are electrically connected to each other through contacts, and the contacts are formed in the diaphragm 
 wherein each of the first, the second, the third, and the fourth detecting portions includes 
 a first end, 
 a second end, 
 a first rectangular portion having a side extending from the first end, 
 a second rectangular portion having a side extending perpendicularly from the side of the first rectangular portion, 
 a third rectangular portion having a side extending from and parallel to the side of the second rectangular portion, 
 a fourth rectangular portion having a side extending perpendicularly from the side of the third rectangular portion to be parallel with the side of the first rectangular portion, 
 a fifth rectangular portion having a side extending perpendicularly from the side of the fourth rectangular portion to be parallel with the side of the third rectangular portion, and 
 a sixth rectangular portion having a side extending perpendicularly from the side of the fifth rectangular portion to the second end to be parallel with the side of the first rectangular portion, 
 wherein, when seen in a direction normal to a main surface of the semiconductor substrate, the diaphragm has a rectangular shape having a first, a second, a third, and a fourth side, 
 wherein the side of the first rectangular portion and the side of the sixth rectangular portion of the first detecting portion each extends perpendicular to the first side, 
 wherein the first side and the third side are parallel to each other, 
 wherein the second side and the fourth side are parallel to each other, 
 wherein the second detecting portion is provided adjacent to the second side, 
 wherein the fourth detecting portion is provided adjacent to the fourth side, 
 wherein the fourth rectangular portion of the second detecting portion has an offset to the fourth rectangular portion of the fourth detecting portion in an extending direction of the side of the fourth rectangular portion of the second detecting portion. 
 
     
     
       2. The semiconductor pressure sensor of  claim 1 , further comprising conductive shielding thin film layers, which are respectively formed on the detecting portions through an insulating film layer, 
 wherein the conductive shielding thin film layers are made of polycrystalline silicon. 
 
     
     
       3. The semiconductor pressure sensor of  claim 1 , further comprising n-type semiconductor regions formed in the diaphragm, the detecting portions being respectively formed in the n-type semiconductor regions,
 wherein the detecting portions form a Wheatstone bridge circuit, and  
 wherein each of the n-type semiconductor regions is connected to a high voltage of the Wheatstone bridge circuit. 
 
     
     
       4. The semiconductor pressure sensor of  claim 1 , further comprising n-type semiconductor regions formed in the diaphragm, the detecting portions being respectively formed in the n-type semiconductor regions,
 wherein the detecting portions form a Wheatstone bridge circuit,  
 wherein two of the n-type semiconductor regions including the piezoresistive elements respectively having therein two of the detecting portions, one end of each of which is connected to a high voltage of the Wheatstone bridge circuit, are electrically connected to each other, and 
 wherein the remaining two of the n-type semiconductor regions including the piezoresistive elements respectively having therein the remaining two of the detecting portions, one end of each of which is connected to a low voltage of the Wheatstone bridge circuit, are electrically connected to each other. 
 
     
     
       5. The semiconductor pressure sensor of  claim 1 , further comprising n-type semiconductor regions formed in the diaphragm, the detecting portions being respectively formed in the n-type semiconductor regions,
 wherein the detecting portions form a Wheatstone bridge circuit,  
 wherein two of the n-type semiconductor regions including the piezoresistive elements respectively having therein two of the detecting portions, one end of each of which is connected to a high voltage of the Wheatstone bridge circuit, are connected commonly to the high voltage of the Wheatstone bridge circuit, 
 wherein an one of the n-type semiconductor region including a first piezoresistive element regions having therein a first detecting portion, one end of which is connected to a low voltage of the Wheatstone bridge circuit, is connected to a first output terminal of the Wheatstone bridge circuit which is connected to the other end of the first piezoresistive element detecting portion, and 
 wherein an the remaining one of the n-type semiconductor region including having therein a second piezoresistive element detecting portion, one end of which is connected to the low voltage of the Wheatstone bridge circuit, is connected to a second output terminal of the Wheatstone bridge circuit which is connected to the other end of the second piezoresistive element detecting portion. 
 
     
     
       6. A semiconductor pressure sensor comprising:
 a semiconductor substrate; 
 a diaphragm formed by thinning a portion of the semiconductor substrate, the diaphragm serving as a pressure receiving portion; 
 n-type semiconductor regions formed in the diaphragm; 
 piezoresistive elements, which are respectively formed in the n-type semiconductor regions; 
 conductive shielding thin film layers, which are respectively formed on the piezoresistive elements through an insulating thin film layer, the piezoresistive elements forming a Wheatstone bridge circuit, 
 wherein the conductive shielding thin film layers, which are formed on the piezoresistive elements connected to a high voltage of the Wheatstone bridge circuit, are electrically connected to each other, and the conductive shielding thin film layers, which are formed on the piezoresistive elements connected to a low voltage of the Wheatstone bridge circuit, are electrically connected to each other. 
 
     
     
       7. The semiconductor pressure sensor of  claim 6 , wherein the conductive shielding thin film layers, which are formed on the piezoresistive elements connected to the high voltage of the Wheatstone bridge, are connected to the high voltage of the Wheatstone bridge circuit, and
 wherein an intermediate potential between a potential of the high voltage of the Wheatstone bridge circuit and a potential of the low voltage of the Wheatstone bridge circuit is applied to the conductive shielding thin film layers, which are formed on the piezoresistive elements connected to the low voltage of the Wheatstone bridge circuit. 
 
     
     
       8. The semiconductor pressure sensor of  claim 7 , wherein the intermediate potential is a potential obtained at an output terminal of one end of the Wheatstone bridge circuit. 
     
     
       9. The semiconductor pressure sensor of  claim 7 , wherein the intermediate potential is a potential obtained at a series connection node of resistors connected in series between the high voltage of the Wheatstone bridge circuit and the low voltage of the Wheatstone bridge circuit. 
     
     
       10. The semiconductor pressure sensor of  claim 2 , further comprising n-type semiconductor regions formed in the diaphragm, the detecting portions being respectively formed in the n-type semiconductor regions,
 wherein the detecting portions form a Wheatstone bridge circuit, and  
 wherein each of the n-type semiconductor regions is connected to a high voltage of the Wheatstone bridge circuit. 
 
     
     
       11. The semiconductor pressure sensor of  claim 2 , further comprising n-type semiconductor regions formed in the diaphragm, the detecting portions being respectively formed in the n-type semiconductor regions,
 wherein the detecting portions form a Wheatstone bridge circuit,  
 wherein two of the n-type semiconductor regions including the piezoresistive elements respectively having therein two of the detecting portions, one end of each of which is connected to a high voltage of the Wheatstone bridge circuit, are electrically connected to each other, and 
 wherein the remaining two of the n-type semiconductor regions including the piezoresistive elements respectively having therein the remaining two of the detecting portions, one end of each of which is connected to a low voltage of the Wheatstone bridge circuit, are electrically connected to each other. 
 
     
     
       12. The semiconductor pressure sensor of  claim 2 , further comprising n-type semiconductor regions formed in the diaphragm, the detecting portions being respectively formed in the n-type semiconductor regions,
 wherein the detecting portions form a Wheatstone bridge circuit,  
 wherein two of the n-type semiconductor regions including the piezoresistive elements respectively having therein two of the detecting portions, one end of each of which is connected to a high voltage of the Wheatstone bridge circuit, are connected commonly to the high voltage of the Wheatstone bridge circuit, 
 wherein an one of the n-type semiconductor region including a first piezoresistive element regions having therein a first detecting portion, one end of which is connected to a low voltage of the Wheatstone bridge circuit, is connected to a first output terminal of the Wheatstone bridge circuit which is connected to the other end of the first piezoresistive element detecting portion, and 
 wherein an the remaining one of the n-type semiconductor region including having therein a second piezoresistive element detecting portion, one end of which is connected to the low voltage of the Wheatstone bridge circuit, is connected to a second output terminal of the Wheatstone bridge circuit which is connected to the other end of the second piezoresistive element detecting portion. 
 
     
     
       13. The semiconductor pressure sensor of claim 1, wherein, when seen in the direction normal to the main surface of the semiconductor substrate, the second rectangular portion has a portion wider than the fifth rectangular portion, and the wider portion is connected to the first rectangular portion. 
     
     
       14. The semiconductor pressure sensor of claim 1, further comprising:
 a first wiring which connects the first end of the first detecting portion and the second end of the second detecting portion,   a second wiring which connects the first end of the second detecting portion and the second end of the third detecting portion,   a third wiring which connects the first end of the third detecting portion and the second end of the fourth detecting portion, and   a fourth wiring which connects the first end of the fourth detecting portion and the second end of the first detecting portion,   wherein the first wiring has a portion parallel to the first side and a portion parallel to the second side,   wherein the second wiring has a portion parallel to the second side and a portion parallel to the third side,   wherein the third wiring has a portion parallel to the third side and a portion parallel to the fourth side, and   wherein the fourth wiring has a portion parallel to said fourth side and a portion parallel portion to the first side.   
     
     
       15. The semiconductor pressure sensor of claim 1, wherein the first, the second, the third, and the fourth detecting portion are piezoresistive. 
     
     
       16. The semiconductor pressure sensor of claim 1, wherein the first, the second, the third, and the fourth detecting portion form a Wheatstone bridge circuit. 
     
     
       17. The semiconductor pressure sensor of claim 1,
 wherein the first detecting portion is provided adjacent to the first side,   wherein the side of the first rectangular portion and the side of sixth rectangular portion of the second detecting portion extend parallel to the second side,   wherein the third detecting portion is provided adjacent to the third side,   wherein the side the first rectangular portion and the side of sixth rectangular portion of the third detecting portion extend perpendicular to the third side, and   wherein the side of the first rectangular portion and the side of the sixth rectangular portion of the fourth detecting portion extend parallel to the fourth side.