Method of making an ultra high density NAND gate using a stacked transistor arrangement
First Claim
1. A method for forming a NAND gate within an integrated circuit, comprising:
- providing a first transistor having a first gate conductor arranged upon a first substrate between a first source implant and a first drain implant;
depositing a first interlevel dielectric upon the first source implant, upon the first drain implant and upon the first gate conductor;
forming an opening through said first interlevel dielectric to said first gate conductor;
filling said opening with a second gate conductor;
forming a gate dielectric upon said second gate conductor;
patterning a second substrate upon said gate dielectric;
implanting a second source implant and a second drain implant into said second substrate to form a second transistor;
depositing a second interlevel dielectric upon and laterally adjacent said second transistor;
repeating the above steps to form a third transistor and a fourth transistor; and
interconnecting said first transistor in series with said third transistor andinterconnecting said second transistor in parallel with said fourth transistor to form said NAND gate.
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Accused Products
Abstract
A process is provided for producing active and passive devices on various levels of a semiconductor topography. As such, the present process can achieve device formation in three dimensions to enhance the overall density at which an integrated circuit is formed. The multi-level fabrication process not only adds to the overall circuit density, but does so with emphasis placed on high performance interconnection between devices on separate levels. The interconnect configuration is made as short as possible between features within one transistor level to features within another transistor level. This interconnect scheme lowers resistivity by forming a gate conductor of an upper level transistor upon a gate conductor of a lower level transistor. Alternatively, the gate conductors can be a single conductive entity. In order to abut the gate conductors together, or form a single gate conductor, the upper level transistor is inverted relative to the lower level transistor. In addition to the inverted, shared gate conductor, the multi-level transistor fabrication process incorporates formation of openings and filling of those openings to produce interconnect to junctions of the upper/lower transistors. Interconnecting the gate conductors of a pair of stacked transistors and connecting specific junctions of those transistors allows development of a high density NAND gate. The NAND gate includes two pairs of stacked transistors, wherein one transistor of a pair can be connected to the other transistor of that pair or connected to one or both transistors of the other pair.
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Citations
9 Claims
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1. A method for forming a NAND gate within an integrated circuit, comprising:
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providing a first transistor having a first gate conductor arranged upon a first substrate between a first source implant and a first drain implant; depositing a first interlevel dielectric upon the first source implant, upon the first drain implant and upon the first gate conductor; forming an opening through said first interlevel dielectric to said first gate conductor; filling said opening with a second gate conductor; forming a gate dielectric upon said second gate conductor; patterning a second substrate upon said gate dielectric; implanting a second source implant and a second drain implant into said second substrate to form a second transistor; depositing a second interlevel dielectric upon and laterally adjacent said second transistor; repeating the above steps to form a third transistor and a fourth transistor; and interconnecting said first transistor in series with said third transistor and interconnecting said second transistor in parallel with said fourth transistor to form said NAND gate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification