Method of doping a semiconductor substrate
AssigneeMotorola, Inc.
InventorsClifford I. Drowley, James A. Teplik, Erik W. Egan
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Abstract
A method of decoupling a step for modulating a defect density from a step for modulating a junction depth. A semiconductor substrate (30) having a portion doped with a dopant (34) is heated to a pre-oxidation anneal temperature in a pre-oxidation anneal step (23). After the pre-oxidation anneal step (23), the semiconductor substrate (30) undergoes an oxidation step (25) which serves as a step for modulating the defect density. Subsequent to the oxidation step (25), the semiconductor substrate (30) undergoes a drive-in step (27) which serves as a step for modulating the junction depth. Then, the temperature of the semiconductor substrate (30) is lowered to allow further processing of the semiconductor substrate (30).
Claims19
A method of temporally spacing a defect density modulation step and a junction depth modulation step, comprising the steps of:
- doping a portion of a substrate with an impurity material of a first conductivity type;
- modulating a defect density, wherein modulating the defect density includes heating the substrate to a temperature of at least 950.degree. C.;
- forming an oxide on the substrate wherein the oxide is formed at a temperature less than the temperature of heating the substrate during the defect density modulation step;
- modulating a junction depth, wherein modulating the junction depth includes heating the substrate to a temperature greater than the temperature at which the oxide is formed;
- removing the oxide;
- and
- forming an epitaxial layer over the substrate.
A method of doping a semiconductor substrate capable of reducing a defect density and independently setting a junction depth, comprising the steps of:
- providing a semiconductor impurity material of a first conductivity type to the semiconductor substrate;
- heating the semiconductor substrate to a temperature of at least 950.degree. C.;
- reducing the temperature of the semiconductor substrate, wherein the semiconductor substrate is in an oxidizing ambient atmosphere at a temperature ranging between 825.degree. C. and 900.degree. C.;
- heating the semiconductor substrate to a temperature ranging between 950.degree. C. and 1200.degree. C.;
- and
- reducing the temperature of the semiconductor substrate to a temperature ranging between 600.degree. C. and 900.degree. C.
A method of providing a buried layer having separate steps for decreasing a defect density of an epitaxial layer and setting a junction depth, comprising the steps of:
- providing a semiconductor substrate having a layer of dielectric material disposed thereon;
- patterning a layer of photoresist on the layer of dielectric material, the patterned layer of photoresist having at least one opening exposing a portion of the layer of dielectric material;
- implanting a dopant of a first conductivity type through the at least one opening, through the exposed portion of the layer of dielectric material, and into the semiconductor substrate;
- removing the patterned layer of photoresist;
- equilibrating the semiconductor substrate at a first temperature;
- performing a pre-oxidation anneal of the semiconductor substrate, the pre-oxidation anneal at a second temperature, wherein the second temperature is greater than the first temperature;
- oxidizing the semiconductor substrate at a third temperature, wherein the third temperature is less than the second temperature;
- driving-in the dopant, wherein the step of driving-in the dopant sets the junction depth and is performed at a fourth temperature, the fourth temperature being greater than the third temperature;
- and
- equilibrating the semiconductor substrate at a fifth temperature.
Dependencies are inferred from the claim text.