EP0160919A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Process for forming ic wafer with buried zener diode
Assignee: Analog Devices Inc
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Filing: 1985-04-30
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Granted: —
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Expires: 2005-04-30
Abstract
Abstract A new process making it possible to produce stable buried Zener diodes in large-sized wafers where slow ramping of diffusion temperatures is required to avoid crystal damage and other adverse effects. The process includes an initial deep ion implantation of p type dopant (boron). A second ion implantation of n type dopant (arsenic) is made over the p type implantation. Both implantations are driven in to the required degree. An additional p type dopant diffusion is made coincident with the base formation by ion implantation to establish connection to the original deep p-doped region, and an additional n type dopant diffusion is made coincident with the emitter formation to establish connection with the n type dopant implantation.
Inventors
- 👤 Stephen M. Hemmah
- 👤 Richard S. Payne
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 22:12
CPC Classifications
H; H10; H10P; H10P30/00; H10P30/20; H10P30/21; H10D; H10D8/00; H10D8/20; H10D8/25; H10P30/202; H10P30/204; H10P30/28
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
133 words
A method of making an IC wafer with a buried Zener diode characterized by the steps of (in any sequence): implanting p-type ions in said wafer to form a p-type first region (20; 56) extending a substantial distance into the wafer; implanting n-type ions in said wafer to form an n-type second region (30; 54) directly over said p-type region and forming therewith an all-implanted sub-surface junction suitable for Zener breakdown; providing means for establishing electrical connection to said n-type second region; and forming with p-type dopant a third region (22; 50) joining said p-type first region below the surface of said wafer and extending out laterally beyond said p-type first region to the surface of said wafer to provide for making electrical connection to the p-type first region of said subsurface junction.
Claim 2
Independent Claim
133 words
A method of making an IC wafer with a buried Zener diode characterized by the steps of (in any sequence): implanting p-type ions in said wafer to form a p-type first region (20; 56) extending a substantial distance into the wafer; implanting n-type ions in said wafer to form an n-type second region (30; 54) directly over said p-type region and forming therewith an all-implanted sub-surface junction suitable for Zener breakdown; providing means for establishing electrical connection to said n-type second region; and forming with p-type dopant a third region (22; 50) joining said p-type first region below the surface of said wafer and extending out laterally beyond said p-type first region to the surface of said wafer to provide for making electrical connection to the p-type first region of said subsurface junction.
Claim 3
Dependent Claim
31 words
The method of claim 1, characterized in that said p-type ions in said sub-surface junction have a higher concentration than said p-type dopant in any surface junction with said n-type ions.
Claim 4
Dependent Claim
20 words
The method of claim 1 or 2, characterized in that said sub-surface junction is formed parallel to the wafer surface.
Claim 5
Dependent Claim
36 words
The method of claim 3, characterized in that said n-type ions extend laterally beyond said p-type ions in any surface region of said wafer in a vertical plane containing said p-type dopant and said n-type ions.
Claim 6
Independent Claim
26 words
The method of any of the preceeding claims, characterized in that said n-type ions make an n++ region and said p-tyge ions make a p++ region.
Claim 7
Dependent Claim
22 words
The method of claim 3 and 5, characterized in that said n++ ions extend laterally beyond said p++ ions in all directions.
Claim 8
Independent Claim
26 words
The method of any of the preceeding claims, characterized in that said p-tyge dopant is driven into said third region of the wafer by ion implantation.
Claim 9
Dependent Claim
44 words
The method of claim 1, characterized in that said connection to said n-type second region is established by placing n-type dopant ions in a surface region which overlaps said implanted n-type ions and is separated from the p-type dopant in said laterally extending region.
Claim 10
Dependent Claim
29 words
The method of claim 8, characterized in that said p-type dopant extends out laterally on opposite sides of said p-type ions, along a line passing through said p-type ions.
Claim 11
Dependent Claim
39 words
The method of claim 9, characterized in that said n-type dopant forms two regions which are on opposite aides of said p-type ions and lie on a second line passing through said p-type ions transversely to said first line.
Claim 12
Dependent Claim
27 words
The method of claim 10, characterized in that the doped region made by said p-type and n-type dopants present a cruciform appearance as seen in plan view.
Claim 13
Dependent Claim
26 words
The method of claim 1, characterized in that said n-type ions and said p-type ions are implanted through a common opening formed by a single mask.
Claim 14
Dependent Claim
43 words
The method of claim 12, characterized in that the opening defined for the n-type ion implantation is slightly enlarged relative to the opening size during the p-type ion implantation, to assure that the n-type ions extend laterally beyond the region of p-type ions.
Claim 15
Dependent Claim
63 words
The method of claim 13, characterized in that said opening for the ion implantation steps is defined by oxide on the wafer; applying nitride to the oxide defining the opening; and etching the oxide between the implantation of the p-type and n-type ions to form an under-cut region around the periphery of the opning, thereby to enlarge the opening for the n-type implant.
Claim 16
Independent Claim
16 words
The method of any of the preceeding claims, characterized in that said n-type ions are arsenic.
Claim 17
Dependent Claim
13 words
The method of claim 15, characterized in that said p-type ions are boron.
Claim 18
Dependent Claim
121 words
An IC wafer with a buried Zener diode characterized by: a first region (20; 56) below the wafer surface and containing implanted p-type ions; a second region (30; 54) above said first region and extending to the surface of the wafer, said second region containing implanted n-type ions; said first and second regions forming an all-implanted sub-surface junction (32; 58) suitable for Zener breakdown; means for establishing electrical connection to said n-type region; and a third region (22; 50) containing p-type dopant joining said first region below the surface of said wafer and extending out laterally beyond said first region to the surface of said wafer to provide for making electrical connection to the p-type region side of said sub-surface junction.
Claim 19
Dependent Claim
121 words
An IC wafer with a buried Zener diode characterized by: a first region (20; 56) below the wafer surface and containing implanted p-type ions; a second region (30; 54) above said first region and extending to the surface of the wafer, said second region containing implanted n-type ions; said first and second regions forming an all-implanted sub-surface junction (32; 58) suitable for Zener breakdown; means for establishing electrical connection to said n-type region; and a third region (22; 50) containing p-type dopant joining said first region below the surface of said wafer and extending out laterally beyond said first region to the surface of said wafer to provide for making electrical connection to the p-type region side of said sub-surface junction.
Claim 20
Dependent Claim
31 words
The device of claim 17, characterized in that said p-type ions in said sub-surface junction have a higher concentration than said p-type dopant in any surface junction with said n-type ions.
Claim 21
Dependent Claim
17 words
The device of claim 18, characterized in that said sub-surface junction is parallel to the wafer surface.
Claim 22
Dependent Claim
25 words
The device of claim 19, characterized in that said n-type ions in said second region extend laterally beyond said p-type ions in said first region.
Claim 23
Dependent Claim
23 words
The device of claim 20, characterized in that said first region contains p++ implanted ions and said second region contains n++ implanted ions.
Claim 24
Independent Claim
27 words
The device of any of the preceeding claims 18 to 21, characterized in that said implanted p-type ions are boron and said implanted n-type ions are arsenic.
References Cited (Backward Citations)
No citation records indexed.
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