EPI defect reduction using rapid thermal annealing
AssigneeMotorola, Inc.
InventorsTerry Hulseweh, Mel Miller
Life of this patent
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Abstract
Formation of defects in epi-layers above buried layers, particularly above arsenic buried layers, is substantially reduced by providing a brief high temperature Rapid Thermal Annealing (RTA) step after buried layer implantation, annealing-activation, and junction drive-in and before epi-layer growth. Among other things, the RTA step reduces the formation of arsenic precipitates which is frequently a consequence of slow cools commonly associated with conventional furnace activation-annealing, junction drive-in, and delineation oxidation prior to epi-layer growth.
Claims18
A method for forming buried layers in semiconductor devices, comprising:
- providing a semiconductor substrate having a principal surface;
- providing a mask on the surface having a first opening;
- implanting a first dopant through the first opening into the substrate;
- heating to a temperature exceeding at least 600.degree. C., at least partly in an oxidizing atmosphere and for a time of about 5 minutes or longer, to activate the implant and oxidize at least the implanted part of the substrate surface;
- thereafter rapidly heating the substrate to a temperature exceeding at least 1000.degree. C. in a time less than 30 seconds and thereafter cooling below about 750.degree. C. in a time less than about 30 seconds;
- and
- forming an epitaxial layer on the substrate surface.
A method for forming buried layers in semiconductor devices, comprising:
- providing a semiconductor substrate having a principal surface;
- providing a mask on the surface having a first opening;
- introducing into the substrate through the first opening a first dopant of diffusivity D in the substrate, where D is the temperature dependent diffusivity measured in cm.sup.2 /sec;
- heating to a temperature and for a time t measured in seconds so that the product (Dt).sup.1/2 has a value greater than 5.times.1O.sup.-6 cm;
- thereafter rapidly heating the substrate to a temperature exceeding at least 1000.degree. C. in a time less than 30 seconds and thereafter cooling below about 750.degree. C. in a time less than about 30 seconds;
- and
- forming an epitaxial layer on the substrate surface.
A method for forming buried layers in semiconductor devices, comprising:
- providing a semiconductor substrate having a principal surface;
- providing a mask on the surface having a first opening;
- introducing into a first region of the substrate through the first opening, a first dopant of a first conductivity type;
- heating to a temperature exceeding about 1000.degree. C. for a time of about 5 minutes or more and then cooling below about 750.degree. C.;
- thereafter rapidly heating the substrate to a temperature exceeding at least 1000.degree. C. in a time less than 30 seconds and thereafter cooling below about 750.degree. C. in a time less than about 30 seconds;
- and
- forming an epitaxial layer on the substrate surface.
Dependencies are inferred from the claim text.