DC testing of integrated circuits and a novel integrated circuit structure to facilitate such testing

Claim 2

IN AN INTEGRATED SEMICONDUCTOR CIRCUIT COMPRISING A PLURALITY OF ACTIVE AND PASSIVE DEVICES INTERCONNECTED BY CONDUCTIVE MEANS INTO A SELECTED CIRCUIT CONFIGURATION, A STRUCTURE FOR ELIMINATING A CIRCUIT PATH WHICH WOULD BE ALTERNATIVE TO A FIRST PATH BETWEEN TWO CIRCUIT NODES IN THE EVENT OF A STRUCTURAL FAILURE WITHIN SAID FIRST PATH COMPRISING A RESISTOR REGION OF ONE CONDUCTIVITY-TYPE IN SAID FIRST PATH CONNECTING SAID TWO CIRCUIT NODES, SAID RESISTOR BEING SURROUNDED BY A SUBSTRATE OF OPPOSITE CONDUCTIVITY-TYPE AND, A PAIR OF CONTACTS TO SAID RESISTOR FOR CONNECTING SAID RESISTOR INTO SAID FIRST PATH, AND A PAIR OF REGIONS OF SAID OPPOSITE CONDUCTIVITY-TYPE, EACH RESPECTIVELY ALSO IN CONTACT WITH A CORRESPONDING ONE OF SAID PAIR OF CONTACTS, SAID PAIR OF REGIONS BEING FULLY ENCLOSED BY AND, THEREBY, JUNCTION-ISOLATED FROM EACH OTHER

Claim 3

The structure of claim 1 wherein said pair of contacts are relatively close to each other and said resistor region is bent so as to provide an elongated first path between said pair of contacts through said resistor.

Claim 4

The structure of claim 1 wherein said pair of regions of oPposite-type conductivity have a lower resistivity than said resistor region, whereby in the event said resistor is missing a low resistivity path is provided between said pair of regions through said substrate also of opposite-type conductivity to shunt and short-circuit said alternative path.

Claim 5

The structure of claim 3 wherein said substrate further includes a low resistivity buried region of said opposite conductivity-type spaced from and disposed between said pair of regions.

Claim 6

The structure of claim 1 wherein substrate of opposite conductivity-type has resistivity substantially the same as said resistor region whereby the path between said pair of contacts through said pair of opposite type regions and through said substrate which shunts said alternative circuit path is a path having substantially the same resistance as the path through said missing resistor would have had.

Claim 7

In an integrated semiconductor circuit comprising a plurality of active and passive devices interconnected by conductive means into a selected circuit configuration, a structure for eliminating a circuit path which would be alternative to a first path between two circuit nodes in the event of a structural failure within said first path comprising a resistor region of one conductivity-type in said first path connecting said two circuit nodes, said resistor being surrounded by a substrate of opposite conductivity-type a pair of spaced contacts to said resistor for connecting said resistor into said first path, and means for connecting said alternative path to said resistor region including a third contact to said resistor region spaced from said pair of contacts, and one of said pair of contacts which is common to both said first path and said alternative path, wherein said common and third contacts are also in contact with a region of said opposite conductivity-type of lower resistivity than said resistor region and fully enclosed within said resistor region, whereby said alternative path is in series with that portion of said resistor region between said third and common contacts so that any defect in said resistor portion will disrupt said alternative path.

Claim 8

In an integrated semiconductor circuit comprising a plurality of active and passive devices interconnected by conductive means into a selected circuit configuration, a structure for eliminating a circuit path which would be alternative to a first path between two circuit nodes in the event of a structural failure within said first path comprising a resistor region of one conductivity-type in said first path connecting said two circuit nodes, said resistor being surrounded by a substrate of opposite conductivity-type a pair of spaced contacts to said resistor for connecting said resistor into said first path, and means for connecting said alternative path to said resistor region including a third contact to said resistor region spaced from said pair of contacts, and one of said pair of contacts which is common to both said first path and said alternative path, wherein said common and third contacts are also in contact with a region of said opposite conductivity-type of lower resistivity than said resistor region and fully enclosed within said resistor region, whereby said alternative path is in series with that portion of said resistor region between said third and common contacts so that any defect in said resistor portion will disrupt said alternative path.