US4784964A
Expired / Lapsed
US
⏱️ 0.0 years remaining
EPI defect reduction using rapid thermal annealing
Assignee: NXP USA Inc
•
Filing: 1987-10-19
•
Granted: 1988-11-15
•
Expires: 2007-10-19
Abstract
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.
Inventors
- 👤 Terry Hulseweh
- 👤 Mel Miller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:35
CPC Classifications
H; H10; H10W; H10W15/00; H10W15/01; Y; Y10; Y10S; Y10S438/00; Y10S438/914; Y10S438/92
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
124 words
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° 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° C. in a time less than 30 seconds and thereafter cooling below about 750° C. in a time less than about 30 seconds; and forming an epitaxial layer on the substrate surface.
Claim 2
Independent Claim
124 words
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° 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° C. in a time less than 30 seconds and thereafter cooling below about 750° C. in a time less than about 30 seconds; and forming an epitaxial layer on the substrate surface.
Claim 3
Dependent Claim
24 words
The method of claim 1 further comprising after the first dopant implanting step, implanting a second dopant of opposite type in the substrate surface.
Claim 4
Dependent Claim
38 words
The method of claim 1 wherein the step of rapidly heating the substrate comprises rapidly heating the substrate in an inert atmosphere to a temperature of about 1100° C., or larger in a time less than 20 seconds.
Claim 5
Dependent Claim
34 words
The method of claim 1 wherein the step of rapidly heating and cooling the substrate comprises cooling the substrate in an inert atmosphere to below about 750° C. in less than about 10 seconds.
Claim 6
Dependent Claim
37 words
The method of claim 1 further comprising after the step of rapidly heating and before the step of rapidly cooling, holding the substrate at a temperature exceeding about 1100° C. for a time of about 1-30 seconds.
Claim 7
Independent Claim
127 words
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 2 /sec; heating to a temperature and for a time t measured in seconds so that the product (Dt) 1/2 has a value greater than 5×1O -6 cm; thereafter rapidly heating the substrate to a temperature exceeding at least 1000° C. in a time less than 30 seconds and thereafter cooling below about 750° C. in a time less than about 30 seconds; and forming an epitaxial layer on the substrate surface.
Claim 8
Independent Claim
127 words
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 2 /sec; heating to a temperature and for a time t measured in seconds so that the product (Dt) 1/2 has a value greater than 5×1O -6 cm; thereafter rapidly heating the substrate to a temperature exceeding at least 1000° C. in a time less than 30 seconds and thereafter cooling below about 750° C. in a time less than about 30 seconds; and forming an epitaxial layer on the substrate surface.
Claim 9
Dependent Claim
23 words
The method of claim 6 further comprising after the first introducing step, introducing a second dopant of opposite type in the substrate surface.
Claim 10
Dependent Claim
38 words
The method of claim 6 wherein the step of rapidly heating the substrate comprises rapidly heating the substrate in an oxidizing atmosphere to a temperature of about 1100° C. or larger in a time less than 20 seconds.
Claim 11
Dependent Claim
34 words
The method of claim 6 wherein the step of rapidly heating and cooling the substrate comprises cooling the substrate in an oxidizing atmosphere to below about 750° C. in less than about 10 seconds.
Claim 12
Dependent Claim
37 words
The method of claim 6 further comprising after the step of rapidly heating and before the step of rapidly cooling, holding the substrate at a temperature exceeding about 1100° C. for a time of about 1-30 seconds.
Claim 13
Independent Claim
116 words
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° C. for a time of about 5 minutes or more and then cooling below about 750° C.; thereafter rapidly heating the substrate to a temperature exceeding at least 1000° C. in a time less than 30 seconds and thereafter cooling below about 750° C. in a time less than about 30 seconds; and forming an epitaxial layer on the substrate surface.
Claim 14
Independent Claim
116 words
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° C. for a time of about 5 minutes or more and then cooling below about 750° C.; thereafter rapidly heating the substrate to a temperature exceeding at least 1000° C. in a time less than 30 seconds and thereafter cooling below about 750° C. in a time less than about 30 seconds; and forming an epitaxial layer on the substrate surface.
Claim 15
Dependent Claim
36 words
The method of claim 11 further comprising after the first introducing step, introducing a second dopant of opposite type in a second region of the substrate surface substantially laterally outside the first region of their substrate.
Claim 16
Dependent Claim
34 words
The method of claim 11 wherein the step of rapidly heating the substrate comprises rapidly heating the substrate to a temperature of about 1100° C. or larger in a time less than 20 seconds.
Claim 17
Dependent Claim
30 words
The method of claim 11 wherein the step of rapidly heating and cooling the substrate comprises cooling the substrate to below about 750° C. in less than about 10 seconds.
Claim 18
Dependent Claim
37 words
The method of claim 11 further comprising after the step of rapidly heating and before the step of rapidly cooling, holding the substrate at a temperature exceeding about 1100° C. for a time of about 1-30 seconds.
Claim 19
Dependent Claim
31 words
The method of claim 11 further comprising, prior to the first heating step, oxidizing a portion of first region of the substrate surface at a temperature less than about 1000° C.
Claim 20
Dependent Claim
29 words
The method of claim 16 further comprising, prior to the oxidizing step, heating to a temperature exceeding about 600° C. but less than 1000° C. in an oxidizing atmosphere.
Claim 21
Dependent Claim
30 words
The method of claim 11 further comprising, prior to the first heating step, heating to a temperature exceeding about 600° C. but less than 1000° C. in an oxidizing atmosphere.
References Cited (Backward Citations)
US4381956A
Cited
US4717687A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-11-15 | 1992-05-16 | 1992-11-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-11-15 | 1996-05-16 | 1996-11-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-11-15 | 2000-05-16 | 2000-11-15 | $7700.00 | Window Closed / Lapsed |