Method of fabricating a one transistor floating-body DRAM cell in bulk CMOS process with electrically isolated charge storage region
First Claim
1. A method of fabricating a one-transistor, floating-body (1T/FB) dynamic random access memory (DRAM) cell, the method comprising:
- forming a buried region having a first conductivity type below an upper surface of a semiconductor region of a semiconductor substrate, the semiconductor region having a second conductivity type, opposite the first conductivity type; and
forming a field-effect transistor in the semiconductor region over the buried region, the field effect transistor having a source and a drain, wherein the buried region, the source and the drain are formed such that a depletion region is located between the buried region, the source and the drain, the depletion region defining a floating body region of the field effect transistor, and providing the sole lateral isolation for portions of the floating body region.
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Abstract
A one-transistor, floating-body (1T/FB) dynamic random access memory (DRAM) cell is provided that includes a field-effect transistor fabricated using a process compatible with a standard CMOS process. The field-effect transistor includes a source region and a drain region of a first conductivity type and a floating body region of a second conductivity type, opposite the first conductivity type, located between the source region and the drain region. A buried region of the first conductivity type is located under the source region, drain region and floating body region. The buried region helps to form a depletion region, which is located between the buried region and the source region, the drain region and the floating body region. The floating body region is thereby isolated by the depletion region. A bias voltage can be applied to the buried region, thereby controlling leakage currents in the 1T/FB DRAM cell.
308 Citations
21 Claims
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1. A method of fabricating a one-transistor, floating-body (1T/FB) dynamic random access memory (DRAM) cell, the method comprising:
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forming a buried region having a first conductivity type below an upper surface of a semiconductor region of a semiconductor substrate, the semiconductor region having a second conductivity type, opposite the first conductivity type; and
forming a field-effect transistor in the semiconductor region over the buried region, the field effect transistor having a source and a drain, wherein the buried region, the source and the drain are formed such that a depletion region is located between the buried region, the source and the drain, the depletion region defining a floating body region of the field effect transistor, and providing the sole lateral isolation for portions of the floating body region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of fabricating a plurality of one-transistor, floating-body (1T/FB) dynamic random access memory (DRAM) cells, the method comprising:
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forming a buried region having a first conductivity type below an upper surface of a semiconductor region of a semiconductor substrate, the semiconductor region having a second conductivity type, opposite the first conductivity type; and
forming a plurality of rows of field-effect transistors in the semiconductor region over the buried region, each of the field effect transistors having a source and a drain, wherein the buried region, and each source and drain are formed such that a continuous depletion region is located between the buried region and each source and drain, the depletion region defining floating body regions of the field effect transistors, and providing lateral isolation for floating body regions located in adjacent rows. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification