Method of making memory cell with vertical transistor and buried word and body lines
First Claim
1. A method of fabricating an integrated circuit, the method comprising the steps of:
- providing a substrate;
forming a plurality of bit lines on the substrate;
forming a plurality of access transistors on each of the bit lines, each access transistor including a first source/drain region shared by at least a portion of the bit line, a body region and second source/drain region formed vertically thereupon;
forming a plurality of isolation trenches in the substrate and orthogonal to the bit lines, each trench located between access transistors on the orthogonal bit lines;
forming in a first one of the trenches a word line that controls conduction between first and second source/drain regions of access transistors that are adjacent to a first side of the first trench; and
forming in a second one of the trenches, adjacent to the first trench, a body line that interconnects body regions of access transistors that are adjacent to a first side of the second trench.
6 Assignments
0 Petitions
Accused Products
Abstract
An integrated circuit and fabrication method includes a vertical transistor for a memory cell in a dynamic random access memory (DRAM) or other integrated circuit. Vertically oriented access transistors are formed on semiconductor pillars on buried bit lines. Buried gates and body contacts are provided for each access transistor on opposing sides of the pillars. Buried word lines extend in first alternating trenches orthogonal to the bit lines. The buried word lines interconnect ones of the gates. Buried body lines extend in second alternating trenches orthogonal to the bit lines. The buried body lines interconnect body regions of adjacent access transistors. Unitary and split-conductor gate and body lines are provided for shared or independent signals to access transistors on either side of the trenches. In one embodiment, the memory cell has a surface area that is approximately 4 F2, where F is a minimum feature size. Bulk-semiconductor and semiconductor-on-insulator (SOI) embodiments are provided.
348 Citations
9 Claims
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1. A method of fabricating an integrated circuit, the method comprising the steps of:
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providing a substrate; forming a plurality of bit lines on the substrate; forming a plurality of access transistors on each of the bit lines, each access transistor including a first source/drain region shared by at least a portion of the bit line, a body region and second source/drain region formed vertically thereupon; forming a plurality of isolation trenches in the substrate and orthogonal to the bit lines, each trench located between access transistors on the orthogonal bit lines; forming in a first one of the trenches a word line that controls conduction between first and second source/drain regions of access transistors that are adjacent to a first side of the first trench; and forming in a second one of the trenches, adjacent to the first trench, a body line that interconnects body regions of access transistors that are adjacent to a first side of the second trench. - View Dependent Claims (2, 3, 4, 5)
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6. A method of fabricating an integrated circuit, the method comprising:
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forming a first conductivity type first source/drain region layer on a substrate; forming a second conductivity type body region layer on the first source/drain layer; forming a first conductivity type second source/drain region layer on the body region layer; forming a plurality of substantially parallel column isolation trenches extending through the second source/drain region layer, the body region layer, and the first source/drain region layer, thereby forming column bars between the column isolation trenches; providing an isolation material in the column isolation trenches; forming a plurality of substantially parallel row isolation trenches, orthogonal to the column isolation trenches, extending through the second source/drain region layer, the body region layer, and at least partially into the first source/drain region layer in the column bars, the row isolation trenches also extending at least partially into the isolation material in the column isolation trenches, thereby forming row bars between the row isolation trenches; forming an insulating layer at the base of the row isolation trenches; forming conductive word lines in first alternating ones of the row isolation trenches; and forming conductive body lines in second alternating ones of the row isolation trenches. - View Dependent Claims (7, 8, 9)
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Specification