Electrical mask identification of memory modules

US6268228A · kind A · utility

Assignee

• International Business Machines Corporation · US

Inventors

• John Bradley Deforge · Barre, US
• David E. Douse · South Burlington, US
• Steven M. Eustis · South Burlington, US
• Erik L. Hedberg · South Burlington, US
• Susan M. Litten · Jericho, US
• Endre P. Thoma · Colchester, US

Key dates

• Filing date: Jan 27, 1999
• Grant date: Jul 31, 2001
• Expiry date: Jan 27, 2019

Classification

• Technology area (CPC G): Physics
• CPC primary: G03F7/70541
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

Mask programmable conductors of the same construction as the mask layers they define are utilized for mask vintage identification. When the actual mask layer is altered, the change is recorded within the mask itself. Mask identification can be fabricated to identify the following type of mask layers: DT--deep trench; SS--surface strap; DIFF--Diffusion; NDIFF--N Diffusion; PDIFF--P Diffusion; WL--N wells; PC--polysilicon gates; BN--N diffusion Implant; BP--P diffusion Implant; C1--first contact; M1--first metal layer; C2--second contact; and, M2--second metal layer. Conducting paths that incorporate, in series, the mask programmable conductor technology devices are: M1-C1-PC-C1-DIFF-C1-M1-C2-M2; M1-C1-PDIFF-SS-DT-SS-PDIFF-C1-M1-C2-M2; M2-C2-M1-C1-PC-C1-M1; M2-C2-M1-C1-NDIFF-WL-NDIFF-C1-M1; and, M2-C2-M1-C1-NDIFF-C1-M1-C1-PC-C1-M1. These conducting paths are electrically opened with the omission of any of the layers in the series path.