Semiconductor floating gate device having improved channel-floating gate interaction
AssigneeMicron Technology, Inc.
InventorRoger R. Lee
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Abstract
Described is an E.sup.2 PROM design comprising a channel region and a floating gate comprising P-type polycrystalline silicon. The work function difference between P-type material effectively increases the threshold voltage of the transistor. This alleviates the need for a boron V.sub.T adjust implant. Implants of material such as boron to set the threshold voltage are known to correlate with problems such as implant ionization and junction (avalanche) breakdown. These two undesired effects can be decreased or eliminated in devices comprising the invention. An optional phosphorous implant into the substrate would allow the lowering of V.sub.T to a desired level.
Claims11
A semiconductor transistor device comprising:
- a) a substrate, said substrate having a transistor source, drain, and channel, said channel comprising a portion having a P-type preinversion conductivity;
- b) a floating gate over said channel for storing a charge, said floating gate having a P-type conductivity;
- and
- c) a word line over said floating gate, said word line for activating a number of transistors from an array of transistors;
- wherein a work function difference between material comprising said channel and material comprising said floating gate results in a device having a desired threshold voltage without a voltage adjust implant.
A semiconductor transistor device comprising:
- a) a substrate, said substrate having a transistor source, drain, and channel, said channel comprising a portion having an N-type preinversion conductivity;
- b) a floating gate over said channel for storing a charge, said floating gate having a P-type conductivity;
- and
- c) a word line over said floating gate, said word line for activating a number of transistors from an array of transistors;
- wherein a work function difference between material comprising said channel and material comprising said floating gate results in a device having a desired threshold voltage without a voltage adjust implant.
A semiconductor transistor device comprising:
- a) a substrate, said substrate having a transistor source, drain, and channel, said channel comprising a portion having an N-type preinversion conductivity;
- b) a floating gate over said channel for storing a charge, said floating gate having a N-type conductivity;
- c) a word line over said floating gate, said word line for activating a number of transistors from an array of transistors;
- and
- d) P-type majority carriers implanted in said channel to lower a threshold voltage of said semiconductor device;
- wherein a work function difference between material comprising said channel and material comprising said floating gate results in a device having a desired threshold voltage without an N-type carrier voltage adjust implant.
Dependencies are inferred from the claim text.