Structure providing poly-resistor under shallow trench isolation and above high resistivity polysilicon layer
Embodiments of the disclosure provide a method, including forming a shallow trench isolation (STI) in a substrate. The method further includes doping the substrate with a noble dopant, thereby forming a disordered crystallographic layer under the STI. The method also includes converting the disordered crystallographic layer to a doped buried polysilicon layer under the STI and a high resistivity (HR) polysilicon layer under the doped buried polysilicon layer. The method includes forming a pair of contacts operatively coupled in a spaced manner to the doped buried polysilicon layer.
1 . A method, comprising:
forming a shallow trench isolation (STI) in a substrate;
doping the substrate with a noble dopant, forming a disordered crystallographic layer under the STI;
converting the disordered crystallographic layer to a doped buried polysilicon layer under the STI and a high resistivity (HR) polysilicon layer under the doped buried polysilicon layer;
forming a pair of contacts operatively coupled in a spaced manner to the doped buried polysilicon layer; and
forming an isolation ring bounding the doped buried polysilicon layer.
2 . The method of claim 1 , further comprising doping to form a retarding implant region below the HR polysilicon layer, within the HR polysilicon layer, or both within and below the HR polysilicon layer.
3 . The method of claim 1 , wherein forming the pair of contacts includes forming a doped monocrystalline semiconductor material extending beside the STI in each of a pair of active regions defined by the STI, and each contact is operatively coupled to a lateral end of the doped buried polysilicon layer, and each contact contacts an upper surface of the HR polysilicon layer.
4 . The method of claim 1 , wherein the STI defines a pair of active regions and each active region includes a pad nitride layer thereover during the doping of the STI with the noble dopant, whereby the doped buried polysilicon layer includes vertical portions extending vertically along lateral sides of the STI in each active region, and wherein forming the pair of contacts includes forming a doped polycrystalline semiconductor material operatively coupled to an upper surface of the vertical portion of the doped buried polysilicon layer in each active region.
5 . The method of claim 1 , wherein forming the pair of contacts includes forming a metal contact that extends through the STI to an upper surface of the doped buried polysilicon layer.
6 . The method of claim 1 , wherein the HR polysilicon layer includes a noble dopant.
7 . The method of claim 1 , wherein the doped buried polysilicon layer under the STI includes a boron dopant.
8 . The method of claim 1 , wherein forming the isolation ring further includes forming a trench isolation.
9 . The method of claim 1 , wherein forming the isolation ring further includes forming a doped well.
10 . The method of claim 1 , further comprising forming a resistor above the STI.
11 . A method, comprising:
forming a shallow trench isolation (STI) in a substrate;
forming a resistor, the resistor including a doped buried polysilicon layer under the STI;
forming a high resistivity (HR) polysilicon layer under the resistor;
forming a pair of contacts operatively coupled in a spaced manner to the resistor; and
forming an isolation ring bounding the doped buried polysilicon layer.
12 . The method of claim 11 , wherein the HR polysilicon layer includes a noble dopant.
13 . The method of claim 11 , wherein the doped buried polysilicon layer includes a boron dopant.
14 . The method of claim 11 , wherein forming each contact in the pair of contacts further includes forming a doped monocrystalline semiconductor material on opposing sides of the STI, each contact being operatively coupled to a lateral end of the doped buried polysilicon layer.
15 . The method of claim 14 , wherein each contact contacts an upper surface of the HR polysilicon layer.
16 . The method of claim 14 , wherein forming the pair of contacts further includes forming an upper layer of each contact in the pair of contacts, wherein the upper layer of each contact in the pair of contacts includes a higher dopant concentration than the doped monocrystalline semiconductor material.
17 . The method of claim 11 , wherein each contact extends through the STI to an upper surface of the doped buried polysilicon layer.
18 . The method of claim 11 , further comprising forming an additional resistor above the STI.
19 . The method of claim 11 , wherein forming the isolation ring further includes forming a trench isolation.
20 . The method of claim 11 , wherein forming the isolation ring further includes forming a doped well.