Patent EP0223694A2 successfully refreshed from Google Patents.
EP0223694A2
Expired / Lapsed
EP
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Submerged wall isolation of silicon islands
Assignee: Fairchild Semiconductor Corp
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Filing: 1986-11-04
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Granted: —
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Expires: 2006-11-04
Abstract
Abstract To completely isolate an island of silicon, a trench is cut into an epitaxial layer to provide access to a differently doped buried layer. While suspending the portion of the epitaxial layer surrounded by the trench by means of an oxide bridge, the underlying region of the buried layer is etched away to form a cavity under the active area. This cavity, as well as the surrounding trench, is then filled with a suitable insulating material to isolate the active island from the substrate.
Inventors
- 👤 Gregory N. Burton
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 14:38
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/60; H10P50/64; H10P50/642; H10P90/00; H10P90/19; H10P90/1904; H10P90/1906; H10W; H10W10/00; H10W10/01; H10W10/041; H10W10/061; H10W10/10; H10W10/181; H10W10/40; H10W10/011; H10W10/012; H10W10/13; Y; Y10; Y10S; Y10S148/00; Y10S148/05; Y10S148/116
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
96 words
A method for isolating a semiconductor island from a surrounding substrate, comprising the steps of: providing a buried region in an area of the substrate corresponding to the location of the island, said buried region having a characteristic response to etching that is different from that of said substrate; forming a trench in said substrate along at least a portion of the island, said trench providing access to said buried region; and etching said buried region to thereby form a cavity beneath at least a portion of the island, to isolate said island from said substrate.
Claim 2
Independent Claim
96 words
A method for isolating a semiconductor island from a surrounding substrate, comprising the steps of: providing a buried region in an area of the substrate corresponding to the location of the island, said buried region having a characteristic response to etching that is different from that of said substrate; forming a trench in said substrate along at least a portion of the island, said trench providing access to said buried region; and etching said buried region to thereby form a cavity beneath at least a portion of the island, to isolate said island from said substrate.
Claim 3
Independent Claim
26 words
The method of claim l, further comprising the step of introducing a material in said cavity and said trench to isolate said island from said substrate.
Claim 4
Dependent Claim
36 words
The method of claim 2 wherein said trench completely surrounds said island and said cavity completely underlies said island, and further including the step of suspending the island in place during said etching and introducing steps.
Claim 5
Dependent Claim
38 words
The method of claim 3 wherein the step of suspending is carried out by forming at least one bridge across said trench, said bridge geing comprised of a material which is not completely removed during said etching step.
Claim 6
Independent Claim
23 words
The method of claim l wherein said buried region has a concentration of impurity atoms which is different from that of said substrate.
Claim 7
Independent Claim
16 words
The method of claim l wherein said trench extends at least partially into said buried region.
Claim 8
Independent Claim
39 words
The method of claim l, further comprising the steps of: lining opposite walls of said trench and said cavity with layers of oxide, and depositing a material between said oxide lining layers, to fill the remainder of said cavity.
Claim 9
Dependent Claim
12 words
The method of claim 7 wherein said deposited material is undoped polysilicon.
Claim 10
Dependent Claim
11 words
The method of claim 2 wherein said material is an insulator.
Claim 11
Dependent Claim
13 words
l0. The method of claim 9 wherein said insulator material is undoped polysilicon.
Claim 12
Dependent Claim
54 words
A semiconductor structure, comprising: a silicon substrate; an epitaxial island of single crystalline silicon disposed over said substrate; an isolation region which completely surrounds said island and physically separates said island from said substrate; and a continuous layer of insulating material disposed within said isolation region to dielectrically isolate said island from said substrate.
Claim 13
Dependent Claim
54 words
A semiconductor structure, comprising: a silicon substrate; an epitaxial island of single crystalline silicon disposed over said substrate; an isolation region which completely surrounds said island and physically separates said island from said substrate; and a continuous layer of insulating material disposed within said isolation region to dielectrically isolate said island from said substrate.
Claim 14
Dependent Claim
42 words
The semiconductor structure of claim ll wherein said layer of insulating material includes a film of oxide at the interface of said isolation region with each of said substrate and said island, and undoped polycrystalline silicon sandwiched between said films of oxide.
Claim 15
Independent Claim
88 words
A method for completely isolating a silicon island from its support substrate, comprising the steps of: growing an epitaxial layer of single-crystalline silicon on a silicon substrate; etching material along the border of a desired region of the epitaxial layer and beneath the desired region at the interface of the epitaxial layer and the substrate to form a cavity which completely surrounds the desired region; and introducing an insulating material into said cavity to provide an island of the epitaxial layer which is dielectrically isolated from the substrate.
Claim 16
Independent Claim
88 words
A method for completely isolating a silicon island from its support substrate, comprising the steps of: growing an epitaxial layer of single-crystalline silicon on a silicon substrate; etching material along the border of a desired region of the epitaxial layer and beneath the desired region at the interface of the epitaxial layer and the substrate to form a cavity which completely surrounds the desired region; and introducing an insulating material into said cavity to provide an island of the epitaxial layer which is dielectrically isolated from the substrate.
Claim 17
Independent Claim
36 words
The method of claim l3 further including the step of supporting the desired region of the epitaxial layer in place while etching the material beneath said region by means of a layer which bridges said border.
Claim 18
Independent Claim
20 words
The method of claim l3 wherein a wet etch is employed during at least a portion of said etching step.
Claim 19
Independent Claim
20 words
The method of claim l3 wherein said introducing step includes lining the walls of the cavity with said insulating material.
References Cited (Backward Citations)
No citation records indexed.
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