USRE28653E
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of fabricating semiconductor devices
Assignee: —
•
Filing: 1972-08-10
•
Granted: 1975-12-16
•
Expires: 1992-08-10
Abstract
Abstract The invention is a method of fabricating semiconductor devices which have the uniform avalanche breakdown junctions characteristic of prior art mesa device structures while retaining the desirable passivation and overlay contact features characteristic of planar structures. An important feature is based on the fact that the bulk increases when silicon is converted to the oxide whereby depressions in a silicon body can be filled by selective oxidation of the regions of the depressions.
Inventors
No inventors recorded.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 21:32
CPC Classifications
H; H10; H10W; H10W74/00; H10W74/40; H10D; H10D99/00; H10P; H10P95/00
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
5 words
the semiconductor material is silicon;
Claim 2
Dependent Claim
5 words
the semiconductor material is silicon;
Claim 3
Dependent Claim
5 words
THE SEMICONDUCTOR MATERIAL IS SILICON;
Claim 4
Dependent Claim
5 words
THE SEMICONDUCTOR MATERIAL IS SILICON;
Claim 5
Dependent Claim
29 words
THE FIRST FORMING STEP PRODUCES AN EPITAXIAL SILICON LAYER WHICH IS ABOUT ONE MICRON THICK ON A THICKER BULK PORTION AND WHICH IS DOPED DIFFERENTLY FROM THE BULK PORTION;
Claim 6
Dependent Claim
29 words
THE FIRST FORMING STEP PRODUCES AN EPITAXIAL SILICON LAYER WHICH IS ABOUT ONE MICRON THICK ON A THICKER BULK PORTION AND WHICH IS DOPED DIFFERENTLY FROM THE BULK PORTION;
Claim 7
Dependent Claim
29 words
the first forming step produces an epitaxial silicon layer which is about one micron thick on a thicker bulk portion and which is doped differently from the bulk portion;
Claim 8
Dependent Claim
29 words
the first forming step produces an epitaxial silicon layer which is about one micron thick on a thicker bulk portion and which is doped differently from the bulk portion;
Claim 9
Dependent Claim
18 words
the first mask is of a material selected from the group consisting of silicon nitride and aluminum oxide,
Claim 10
Dependent Claim
18 words
the first mask is of a material selected from the group consisting of silicon nitride and aluminum oxide,
Claim 11
Dependent Claim
18 words
THE FIRST MASK IS OF A MATERIAL SELECTED FROM THE GROUP CONSISTING OF SILICON NITRIDE AND ALUMINUM OXIDE,
Claim 12
Dependent Claim
18 words
THE FIRST MASK IS OF A MATERIAL SELECTED FROM THE GROUP CONSISTING OF SILICON NITRIDE AND ALUMINUM OXIDE,
Claim 13
Dependent Claim
13 words
THE UNMASKED REGIONS ARE ETCHED TO A DEPTH OF ABOUT 0.7 MICRON, AND
Claim 14
Dependent Claim
13 words
THE UNMASKED REGIONS ARE ETCHED TO A DEPTH OF ABOUT 0.7 MICRON, AND
Claim 15
Dependent Claim
13 words
the unmasked regions are etched to a depth of about 0.7 micron, and
Claim 16
Dependent Claim
13 words
the unmasked regions are etched to a depth of about 0.7 micron, and
Claim 17
Dependent Claim
14 words
the first mask is removed by etching in a solution of hot phosphoric acid.
Claim 18
Dependent Claim
14 words
the first mask is removed by etching in a solution of hot phosphoric acid.
Claim 19
Dependent Claim
14 words
THE FIRST MASK IS REMOVED BY ETCHING IN A SOLUTION OF HOT PHOSPHORIC ACID.
Claim 20
Dependent Claim
14 words
THE FIRST MASK IS REMOVED BY ETCHING IN A SOLUTION OF HOT PHOSPHORIC ACID.
Claim 21
Independent Claim
181 words
A METHOD FOR FABRICATING A SEMICONDUCTOR DEVICE COMPRISING THE STEPS OF: FIRST FORMING A SEMICONDUCTIVE EPITAXIAL LAYER ON A SEMICONDUCTIVE BULK PORTION, THE BULK PORTION AND THE LAYER CONSTITUTING A SEMICONDUCTIVE BODY; SECOND FORMING ON THE SURFACE OF THE EPITAXIAL LAYER A FIRST MASK OF A MATERIAL HAVING THE CHARACTERISTICS THAT IS RESISTS ETCHING IN A FIRST AMBIENT WHICH ETCHES THE SEMICONDUCTOR MATERIAL, IT INHIBITS OXIDATION OF THE UNDERLYING SEMICONDUCTOR MATERIAL DURING A SUBSEQUENT STEP IN WHICH THE UNMASKED PORTION OF THE SURFACE IS OXIDIZED, AND IT IS REMOVABLE BY ETCHING IN A SECOND AMBIENT WHICH ATTACKS THE MASK BUT DOES NOT APPRECIABLY ATTACK THE GROWN OXIDE OF THE SEMICONDUCTOR MATERIAL; IMMERSING THE BODY IN THE FIRST AMBIENT SO THAT THE UNMASKED PORTIONS OF THE SURFACE OF THE EPITAXIAL LYER ARE REMOVED BY ETCHING AT LEAST PARTIALLY THROUGH THE EPITAXIAL LAYER TO FORM A MESA; EXPOSING THE BODY AT AN ELVATED TEMPERATURE TO A SECOND AMBIENT SUFFICIENT TO OXIDIZE THE UNMASKED PORTIONS OF THE EPITAXIAL LAYER FOR A TIME SUFFICIENT THAT THE OXIDE GROWN THERE EXTENDS ESSENTIALLY COMPLETELY THROUGH THE EPITAXIAL
Claim 22
Independent Claim
181 words
A METHOD FOR FABRICATING A SEMICONDUCTOR DEVICE COMPRISING THE STEPS OF: FIRST FORMING A SEMICONDUCTIVE EPITAXIAL LAYER ON A SEMICONDUCTIVE BULK PORTION, THE BULK PORTION AND THE LAYER CONSTITUTING A SEMICONDUCTIVE BODY; SECOND FORMING ON THE SURFACE OF THE EPITAXIAL LAYER A FIRST MASK OF A MATERIAL HAVING THE CHARACTERISTICS THAT IS RESISTS ETCHING IN A FIRST AMBIENT WHICH ETCHES THE SEMICONDUCTOR MATERIAL, IT INHIBITS OXIDATION OF THE UNDERLYING SEMICONDUCTOR MATERIAL DURING A SUBSEQUENT STEP IN WHICH THE UNMASKED PORTION OF THE SURFACE IS OXIDIZED, AND IT IS REMOVABLE BY ETCHING IN A SECOND AMBIENT WHICH ATTACKS THE MASK BUT DOES NOT APPRECIABLY ATTACK THE GROWN OXIDE OF THE SEMICONDUCTOR MATERIAL; IMMERSING THE BODY IN THE FIRST AMBIENT SO THAT THE UNMASKED PORTIONS OF THE SURFACE OF THE EPITAXIAL LYER ARE REMOVED BY ETCHING AT LEAST PARTIALLY THROUGH THE EPITAXIAL LAYER TO FORM A MESA; EXPOSING THE BODY AT AN ELVATED TEMPERATURE TO A SECOND AMBIENT SUFFICIENT TO OXIDIZE THE UNMASKED PORTIONS OF THE EPITAXIAL LAYER FOR A TIME SUFFICIENT THAT THE OXIDE GROWN THERE EXTENDS ESSENTIALLY COMPLETELY THROUGH THE EPITAXIAL
Claim 23
Dependent Claim
48 words
A method as recited in claim 12 wherein the impurities introduced into the exposed semiconductor portions are of a type and amount sufficient to form in the mesa a plane rectifying junction which intersects the sides of the mesa where such sides are covered by the grown oxide.
Claim 24
Dependent Claim
25 words
A method recited in claim 13 further characterized in that the semiconductor body comprises a low resistivity substrate and a higher resistivity epitaxial layer thereon.
Claim 25
Dependent Claim
35 words
A method recited in claim 14 further characterized in that the introduced impurities convert at least a portion of the epitaxial layer to a zone of conductivity type opposite to that of the epitaxial layer.
Claim 26
Dependent Claim
62 words
A method as recited in claim 15 wherein the impurities introduced form in said zone P-type conductivity in the upper part of the mesa, an N-type zone remaining between the P-type zone and the bulk portion, and wherein electrical contacts are made to the P-type zone and the bulk portion so that the device is capable of functioning as an IMPATT diode.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-15 | 1979-06-16 | 1979-12-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-15 | 1983-06-16 | 1983-12-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-15 | 1987-06-16 | 1987-12-16 | $7700.00 | Window Closed / Lapsed |