EP0017022A1
Expired / Lapsed
EP
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A zener diode and method of fabrication thereof
Assignee: International Business Machines Corp
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Filing: 1980-03-11
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Granted: —
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Expires: 2000-03-11
Abstract
Abstract This invention relates to a subsurface breakdown zener diode having an internally protected P-N junction and a method of fabrication thereof. A semiconductor substrate (10) of one conductivity type (P) has a deposit of semiconductor material (P + ) of the same conductivity type but more heavily doped over which an epitaxial layer (14') of semiconductor material of another semiconductor conductivity type (N) is grown and whereby the deposit becomes a buried layer (12'). Semiconductor material of the one conductivity type and intermediate doping is diffused into an annular region (18) in the epitaxial layer while at the same time a quantity of the same material is diffused into a region (20') centrally of and spaced from the annular region (18'). Both diffusions are carried out to contact with the buried layer (12'). Material (28') of the other conductivity type and doped more heavily than the epitaxial layer (14') is diffused over the centrally diffused material and carried out to convert the first diffusion to the opposite conductivity type for a substantial depth into the epitaxial layer (14') whereby a pn + junction is formed completely beneath the surface. Contacts for the zener diode are made to the annular diffusion region (18') and the diffusion region (28').
Inventors
- 👤 Bruce Coleman Atwood
- 👤 Raymond Allen Muggli
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 04:30
CPC Classifications
H; H10; H10D; H10D84/00; H10D84/201; H10D84/204; H10D84/221; H10D8/00; H10D8/20; H10D8/25; H10D84/60; H10D84/611; H10D84/613; H10D84/617
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
228 words
A zener diode assembly, characterised in that the assembly comprises, a semiconductor substrate (10) of a first semiconductor conductivity type material (P), a layer (14') of semiconductor material of a second semiconductor conductivity type (N) arranged over said substrate (10) and extending from said substrate to a facing surface, a layer (12') of said first semiconductor conduc-. tivity type buried in said substrate (10) and in the first said layer (14') and beneath said facing surface, a first portion (28') of semiconductor material of said second semiconductor conductivity type arranged in said layer (14') of semiconductor material and extending from said facing surface toward said buried layer (12') and spaced therefrom, a second portion (18') of semiconductor material of said first semiconductor conductivity type arranged in said layer (14') and spaced from said first portion (28') and extending from said facing surface to said buried layer (12'), and a third portion (20') of semiconductor material of said first semiconductor conductivity type arranged in said layer (14') and spaced from said second portion (18') and contained between the surface of said first portion (28') remote from said facing surface and said buried layer (12'), said buried layer (12') having a dopant concentration higher than that of said substrate (10) and said third portion (20') having a dopant concentration intermediate those of said substrate (10) and said buried layer (12').
Claim 2
Dependent Claim
228 words
A zener diode assembly, characterised in that the assembly comprises, a semiconductor substrate (10) of a first semiconductor conductivity type material (P), a layer (14') of semiconductor material of a second semiconductor conductivity type (N) arranged over said substrate (10) and extending from said substrate to a facing surface, a layer (12') of said first semiconductor conduc-. tivity type buried in said substrate (10) and in the first said layer (14') and beneath said facing surface, a first portion (28') of semiconductor material of said second semiconductor conductivity type arranged in said layer (14') of semiconductor material and extending from said facing surface toward said buried layer (12') and spaced therefrom, a second portion (18') of semiconductor material of said first semiconductor conductivity type arranged in said layer (14') and spaced from said first portion (28') and extending from said facing surface to said buried layer (12'), and a third portion (20') of semiconductor material of said first semiconductor conductivity type arranged in said layer (14') and spaced from said second portion (18') and contained between the surface of said first portion (28') remote from said facing surface and said buried layer (12'), said buried layer (12') having a dopant concentration higher than that of said substrate (10) and said third portion (20') having a dopant concentration intermediate those of said substrate (10) and said buried layer (12').
Claim 3
Dependent Claim
33 words
A zener diode assembly as claimed in claim 1, including a first element of conductive material electrically contacting said first portion, and a second element of conductive material electrically contacting said second portion.
Claim 4
Dependent Claim
32 words
A zener diode assembly as claimed in claim 1 or 2, including a fourth portion of semiconductor material of said second semiconductor conductivity type interposed between said substrate and said buried layer.
Claim 5
Dependent Claim
25 words
A zener diode assembly as claimed in claim 3, where said fourth portion has a dopant concentration substantially equal to that of said first portion.
Claim 6
Dependent Claim
24 words
A zener diode assembly as claimed in any one of the preceding claims, wherein said second portion is arranged entirely around said first portion.
Claim 7
Dependent Claim
36 words
A zener diode assembly as claimed in any one of the preceding claims, wherein said first portion has a dopant concentration greater than that of said layer of said second conductivity type arranged over said substrate.
Claim 8
Independent Claim
266 words
A method for producing a zener diode assembly characterised in that the method comprises the steps of selecting a substrate (10) of a first semiconductor conductivity type material (P), depositing on said substrate (10) semiconductor material of said first conductivity type having a dopant concentration higher than that of said substrate (10), growing a layer (14') of semiconductor material of a second semiconductor conductivity type (N) over said substrate (10) and said deposited material whereby, due to subsequent steps, said deposited material diffuses into said substrate and into said grown layer (14') and becomes a buried layer (12') beneath a facing surface of said grown layer (14'), diffusing a quantity of semiconductor material (20') of said first conductivity type into said grown layer (14') centrally of said buried layer (12') and another quantity of said material (18') in a region surrounding and spaced apart from said centrally arranged quantity with both of said quantities being diffused into contact with said buried layer (12'), and said quantities having a dopant concentration intermediate that of said substrate (10) and said buried layer (12'), diffusing another quantity (28') of semiconductor material of said second conductivity type and higher concentration than that of said grown layer (14') into said centrally located diffusion of said first conductivity type and into a region of said grown layer (14') and spaced from said diffusion of said other quantity (18') for subsequently producing an integral region of said second semiconductor conductivity type at said facing surface and a semiconductor junction of said first and said second semiconductor conductivity types within said grown layer (14').
Claim 9
Independent Claim
266 words
A method for producing a zener diode assembly characterised in that the method comprises the steps of selecting a substrate (10) of a first semiconductor conductivity type material (P), depositing on said substrate (10) semiconductor material of said first conductivity type having a dopant concentration higher than that of said substrate (10), growing a layer (14') of semiconductor material of a second semiconductor conductivity type (N) over said substrate (10) and said deposited material whereby, due to subsequent steps, said deposited material diffuses into said substrate and into said grown layer (14') and becomes a buried layer (12') beneath a facing surface of said grown layer (14'), diffusing a quantity of semiconductor material (20') of said first conductivity type into said grown layer (14') centrally of said buried layer (12') and another quantity of said material (18') in a region surrounding and spaced apart from said centrally arranged quantity with both of said quantities being diffused into contact with said buried layer (12'), and said quantities having a dopant concentration intermediate that of said substrate (10) and said buried layer (12'), diffusing another quantity (28') of semiconductor material of said second conductivity type and higher concentration than that of said grown layer (14') into said centrally located diffusion of said first conductivity type and into a region of said grown layer (14') and spaced from said diffusion of said other quantity (18') for subsequently producing an integral region of said second semiconductor conductivity type at said facing surface and a semiconductor junction of said first and said second semiconductor conductivity types within said grown layer (14').
Claim 10
Dependent Claim
45 words
A method as claimed in claim 7, including forming electric contacts on a portion of said centrally located diffusion of semiconductor material of said second conductivity type and on a portion of said diffusion of said other quantity of material of said first conductivity type.
Claim 11
Dependent Claim
31 words
A method as claimed in claim 7 or 8, including diffusing material of said second conductivity type into said substrate over which said material of said first conductivity type is deposited.
Claim 12
Independent Claim
23 words
A method as claimed in any one of claims 7, 8 and 9, wherein said diffusing steps are replaced by ion implantation steps.
References Cited (Backward Citations)
No citation records indexed.
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