Abstract A diffusion resistor is provided that utilizes the block mask to cover only the intrinsic polysilicon gate region. The n-type source/drain doping is implanted in the contact regions, but not in the intrinsic polysilicon gate region. A N-type (or P-type) diffusion resistor in P-well (or N-well) is provided that utilizes a block mask to cover only the intrinsic polysilicon gate region. The N-type (or P-type) source/drain doping is implanted in the contact regions but not in the intrinsic polysilicon gate region. The P-well (or N-well) block mask is used to keep the P-well (or N-well) from forming under the buried resistor. This makes the parasitic capacitance of the diffusion junction very low. Also provided is a buried capacitor and method of making both a buried resistor and a buried capacitor.
A method of forming a buried resistor comprising the steps of: providing a substrate of a first type impurity; disposing a first mask on the substrate to define a buried resistor region in the substrate; forming an isolation region in the substrate around the buried resistor region; performing a resistor formation implant having a second type impurity in the buried resistor region; disposing a second mask to block a well implant of the first type impurity from entering the buried resistor region; performing said well implant of the first type impurity; forming an insulator layer on a portion of the buried resistor region; forming a polysilicon layer on the insulator layer: disposing a blocking mask over the polysilicon layer; and implanting the second type impurity into terminal regions of the buried resistor region.
Claim 2
Independent Claim
133 words
A method of forming a buried resistor comprising the steps of: providing a substrate of a first type impurity; disposing a first mask on the substrate to define a buried resistor region in the substrate; forming an isolation region in the substrate around the buried resistor region; performing a resistor formation implant having a second type impurity in the buried resistor region; disposing a second mask to block a well implant of the first type impurity from entering the buried resistor region; performing said well implant of the first type impurity; forming an insulator layer on a portion of the buried resistor region; forming a polysilicon layer on the insulator layer: disposing a blocking mask over the polysilicon layer; and implanting the second type impurity into terminal regions of the buried resistor region.
Claim 3
Independent Claim
17 words
The method of clam 1, further comprising the step of: forming electrical contacts on the terminal regions.
Claim 4
Independent Claim
17 words
The method of clam 1, further comprising the step of: forming electrical contacts on the terminal regions.