EP0253724A1
Expired / Lapsed
EP
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A method of simultaneously fabricating bipolar and complementary field effect transistors using a minimal number of masks
Assignee: Fairchild Semiconductor Corp
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Filing: 1987-07-10
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Granted: —
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Expires: 2007-07-10
Abstract
Abstract A process is disclosed for simultaneously fabricating bipolar and complementary field effect transistors. The process includes the fabrication of buried layers 18 doped with both phosphorus and arsenic to permit a shorter diffusion time while simultaneously providing buried layers having low resistance and high diffusivity. The process enables fabrication of BiCMOS structures using only six masks prior to the contact mask.
Inventors
- 👤 Juliana Manoliu
- 👤 Prateep Tuntasood
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 03:16
CPC Classifications
H; H10; H10W; H10W15/00; H10D; H10D84/00; H10D84/01; H10D84/0107; H10D84/0109; H10D84/02; H10D84/03; H10D84/038; H10W15/01
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
97 words
A method of fabricating a semiconductor structure on a first conductivity type substrate comprising: introducing a first impurity of second conductivity type into at least one first region of the substrate; introducing a second impurity of second conductivity type into the first region; forming an epitaxial layer over the substrate; introducing second conductivity type impurity into at least one first region of the epitaxial layer overlying the first region of the substrate; and heating the structure to cause the second conductivity type impurity in the epitaxial layer and in the substrate to diffuse to contact each other.
Claim 2
Independent Claim
97 words
A method of fabricating a semiconductor structure on a first conductivity type substrate comprising: introducing a first impurity of second conductivity type into at least one first region of the substrate; introducing a second impurity of second conductivity type into the first region; forming an epitaxial layer over the substrate; introducing second conductivity type impurity into at least one first region of the epitaxial layer overlying the first region of the substrate; and heating the structure to cause the second conductivity type impurity in the epitaxial layer and in the substrate to diffuse to contact each other.
Claim 3
Dependent Claim
17 words
A method as in Claim 1 wherein the step of introducing a first impurity comprises introducing phosphorus.
Claim 4
Dependent Claim
17 words
A method as in Claim 2 wherein the step of introducing a second impurity comprises introducing arsenic.
Claim 5
Dependent Claim
32 words
A method as in Claim 3 wherein the phosphorus concentration comprises approximately 3×10¹³ to 3×10¹⁴ atoms per square centimeter and the arsenic concentration comprises approximately 1×10¹⁵ to 1×10¹⁶ atoms per square centimeter.
Claim 6
Dependent Claim
28 words
A method as in Claim 4 wherein the step of heating the structure comprises heating it to a temperature of approximately 1050°C - 1100°C for approximately 1-2 hours.
Claim 7
Dependent Claim
25 words
A method as in Claim 1 further comprising, prior to the step of heating, the step of fabricating a mask to define field oxide regions.
Claim 8
Dependent Claim
22 words
A method as in Claim 6 wherein the step of heating further comprises oxidizing the epitaxial layer to form field oxide regions.
Claim 9
Dependent Claim
21 words
A method as in Claim 1 wherein the substrate comprises P conductivity type silicon having a resistivity of 11-18 ohm centimeters.
Claim 10
Dependent Claim
28 words
A method as in Claim 8 wherein the step of forming an epitaxial layer is preceded by a step of doping the substrate with P conductivity type impurity.
Claim 11
Dependent Claim
13 words
A method as in Claim 9 wherein the substrate is doped with boron.
Claim 12
Dependent Claim
21 words
A method as in Claim 10 wherein the boron comprises a dose of approximately 3×10¹² to 5×10¹³ atoms per square centimeter.
Claim 13
Dependent Claim
34 words
A method as in Claim 1 wherein the step of introducing into at least one first region is preceded by a step of forming a mask to define the at least one first region.
Claim 14
Dependent Claim
17 words
A method as in Claim 12 wherein the at least one first region comprises a buried layer.
Claim 15
Dependent Claim
18 words
A method as in Claim 1 wherein the step of forming an epitaxial layer comprises depositing undoped silicon.
Claim 16
Dependent Claim
29 words
A method as in Claim 14 wherein the step of forming an epitaxial layer is followed by a step of introducing P conductivity type impurity into the epitaxial layer.
Claim 17
Dependent Claim
36 words
A method as in Claim 15 wherein the step of introducing into at least one first region of the epitaxial layer is preceded by a step of masking the epitaxial layer except for the first region.
Claim 18
Dependent Claim
24 words
A method as in Claim 16 wherein the second conductivity type comprises phosphorus and the impurity concentration is approximately 1-2×10¹² atoms per square centimeter.
Claim 19
Dependent Claim
69 words
A method as in Claim 1 wherein: the step of introducing a first impurity into at least one first region comprises introducing a first impurity into a pair of first regions of the substrate; and the step of introducing second conductivity type impurity into at least one first region of the epitaxial layer comprises introducing second conductivity type impurity into a pair of first regions of the epitaxial layer.
Claim 20
Dependent Claim
81 words
A method as in Claim 18 wherein the pair of first regions of the epitaxial layer comprise a first well spaced apart from a second well, and the epitaxial layer between the first well and the second well comprises a third well, and wherein the method further comprises: forming a first channel type field effect transistor in the first well; forming a bipolar transistor in the second well; and forming a second channel type field effect transistor in the third well.
Claim 21
Dependent Claim
22 words
A method as in Claim 19 wherein the first channel type comprises P channel, and the second channel type comprises N channel.
Claim 22
Dependent Claim
59 words
A method as in Claim 18 wherein the pair of first regions of the epitaxial layer comprise a first well spaced apart from a second well, and the epitaxial layer between the first well and the second well comprises a third well, and wherein the method further comprises: forming transistors in each of the first, second and third wells.
Claim 23
Dependent Claim
92 words
A method as in Claim 21 wherein the step of forming transistors comprises: forming a first layer of insulating material across the surface of the epitaxial layer; introducing first conductivity type impurity into the surface of the epitaxial layer in the second well; forming electrodes on the insulating material over the first and third wells; introducing first conductivity type impurity into the first well and into the region of first conductivity type in the second well; and introducing second conductivity type impurity into the third well on opposite sides of the electrode.
Claim 24
Independent Claim
129 words
A method of fabricating a semiconductor structure adapted for the subsequent formation of both bipolar and complementary field effect transistors comprising: implanting P conductivity type impurity into all of a semiconductor substrate; implanting a first N conductivity type impurity into a first region of the substrate where a buried layer is to be formed; implanting a second N conductivity type impurity of different diffusivity into the first region; depositing an epitaxial layer of semiconductor material over the substrate; implanting N conductivity type impurity into a first region of the epitaxial layer overlying the first region of the substrate; and heating the structure to cause one of the first or the second N conductivity type impurities in the substrate to contact the N conductivity type impurity in the epitaxial layer.
Claim 25
Independent Claim
129 words
A method of fabricating a semiconductor structure adapted for the subsequent formation of both bipolar and complementary field effect transistors comprising: implanting P conductivity type impurity into all of a semiconductor substrate; implanting a first N conductivity type impurity into a first region of the substrate where a buried layer is to be formed; implanting a second N conductivity type impurity of different diffusivity into the first region; depositing an epitaxial layer of semiconductor material over the substrate; implanting N conductivity type impurity into a first region of the epitaxial layer overlying the first region of the substrate; and heating the structure to cause one of the first or the second N conductivity type impurities in the substrate to contact the N conductivity type impurity in the epitaxial layer.
Claim 26
Independent Claim
218 words
A method of fabricating a semiconductor structure comprising: using a first mask, implanting first N conductivity type impurity into first and second spaced-apart regions of the substrate where first and second spaced-apart buried layers are to be formed; implanting second N conductivity type impurity into the first and second spaced-apart regions; introducing P conductivity type impurity into all of a semiconductor substrate; depositing an epitaxial layer over the substrate; using a second mask, implanting N conductivity type impurity into first and second spaced-apart regions of the epitaxial layer overlying the first and second spaced-apart regions of the substrate; using a third mask, oxidizing field regions of the epitaxial layer to separate the first and second regions of the epitaxial layer from adjacent regions of the epitaxial layer; using a fourth mask, implanting P conductivity type impurity into a first portion of the first region of the epitaxial layer; using a fifth mask defining electrodes over a second portion of each of the first and second regions of the epitaxial layer as well as over an intervening region of the epitaxial layer between each of the first and second regions of the epitaxial layer; and using a sixth mask introducing N conductivity type dopant adjacent the electrode over the intervening region and adjacent the electrode over the first region.
Claim 27
Independent Claim
218 words
A method of fabricating a semiconductor structure comprising: using a first mask, implanting first N conductivity type impurity into first and second spaced-apart regions of the substrate where first and second spaced-apart buried layers are to be formed; implanting second N conductivity type impurity into the first and second spaced-apart regions; introducing P conductivity type impurity into all of a semiconductor substrate; depositing an epitaxial layer over the substrate; using a second mask, implanting N conductivity type impurity into first and second spaced-apart regions of the epitaxial layer overlying the first and second spaced-apart regions of the substrate; using a third mask, oxidizing field regions of the epitaxial layer to separate the first and second regions of the epitaxial layer from adjacent regions of the epitaxial layer; using a fourth mask, implanting P conductivity type impurity into a first portion of the first region of the epitaxial layer; using a fifth mask defining electrodes over a second portion of each of the first and second regions of the epitaxial layer as well as over an intervening region of the epitaxial layer between each of the first and second regions of the epitaxial layer; and using a sixth mask introducing N conductivity type dopant adjacent the electrode over the intervening region and adjacent the electrode over the first region.
Claim 28
Dependent Claim
61 words
A method as in Claim 24 wherein a BiCMOS structure is formed and wherein: the first mask defines the buried layers; the second mask defines N type wells; the third mask defines field oxide; the fourth mask defines a bipolar base; the fifth mask defines gate electrodes; and the sixth mask defines an NMOS source and drain and the bipolar emitter.
References Cited (Backward Citations)
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