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US 7,923,815 B2Granted
DRAM having deep trench capacitors with lightly doped buried plates
AssigneeInternational Business Machines Corporation
InventorsGeng Wang, Kangguo Cheng, Johnathan E. Faltermeier, Paul C. Parries
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Abstract
By controlling buried plate doping level and bias condition, different capacitances can be obtained from capacitors on the same chip with the same layout and deep trench process. The capacitors may be storage capacitors of DRAM/eDRAM cells. The doping concentration may be less than 3E19cm−3, a voltage difference between the biases of the buried electrodes may be at least 0.5V, and a capacitance of one capacitor may be at least 1.2 times, such as 2.0 times the capacitance of another capacitor.
Claims11
A microelectronic element comprising:
- a semiconductor substrate;
- a first capacitor comprising a trench formed in the substrate, a first buried plate surrounding the trench, a node dielectric lining the trench, and a node disposed within the trench, and wherein the first buried plate has a first doping concentration;
- a second capacitor comprising a trench formed in the substrate, a second buried plate surrounding the trench, a node dielectric lining the trench, and a node disposed within the trench, and wherein the second buried plate has a second doping concentration;
- a first contact plug directly connected to the first buried plate for applying a first bias voltage to the first buried plate;
- a second contact plug directly connected to the second buried plate for applying a second bias voltage, different than the first bias voltage, to the second buried plate;
- and
- the semiconductor substrate having a non-uniform doping concentration wherein the first doping concentration differs from the second doping concentration by at least one order of magnitude.
4 more elements
Dependencies are inferred from the claim text.