Invalidity dossier
US 7491629
Method for producing an n-doped field stop zone in a semiconductor body and semiconductor component having a field stop zone
Current assignee: Infineon Technologies Austria AG
Added 9/23/2026, 9:33:49 PM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US 7,491,629 B2
Title: Method for producing an n-doped field stop zone in a semiconductor body and semiconductor component having a field stop zone
Assignee: Infineon Technologies Austria AG (original and current assignee per the supplied text). Inventor: Hans-Joachim Schulze.
Key dates (as supplied): Priority date 2004-08-12; filing date 2005-08-11; publication of US20060035436A1 on 2006-02-16; patent granted/publication date 2009-02-17; legal status listed as Active, with adjusted expiration 2026-12-06.
Purpose and plain-language scope: Power IGBTs suffer overall power loss during operation. Inserting an n-doped field stop zone—doped more highly than the n-type base and preceding the p-type emitter or collector—can reduce that loss. Conventional phosphorus indiffusion is slow, requiring very long, very high-temperature diffusions (weeks above 1200° C for ~200 µm), which stresses the semiconductor body, raises oxygen concentration, risks thermal donors and recombination/generation centers, and cannot easily flatten the doping gradient.
The invention instead diffuses sulfur, hydrogen, or selenium from one side into the semiconductor body to form a first n-doped zone, then forms a second, more highly doped n-doped zone within the first. Diffusion duration and temperature depend on the desired penetration depth. Sulfur and hydrogen diffuse quickly: sulfur yields roughly 250 µm in about 10 hours at about 1000° C; hydrogen yields 250–500 µm in 30–120 minutes at about 400° C. Penetration depths from 30 µm to over 300 µm are achievable in well under 24 hours. The first zone may be diffused to its final desired size, or diffused deeper and then thinned/ground back to final dimensions. A power IGBT with such a field stop zone is described (FIG. 4).
What the excerpt does not establish: It gives no claim-by-claim scope, no complete claims text, no full description, no examples beyond those quoted, and no comparative data. Legal status and dates are noted as assumptions, not conclusions. Prior-art discussion (e.g., DE 100 53 445 C2, DE 198 29 614 A1, 102 43 758 A1) is merely referenced, not analyzed. Litigation, ownership transfers, validity, and independent prior-art assessment were excluded.
Generated 10/1/2026, 9:34:13 PM
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Prior art
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