Browse Prior Art Database

Single-Cell Identification System for VLSI Arrays

IP.com Disclosure Number: IPCOM000041320D
Original Publication Date: 1984-Jan-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 73K

Publishing Venue

IBM

Related People

Keinert, J: AUTHOR [+4]

Abstract

The described method is used for single-cell analysis in VLSI structures of memories, gate arrays, and the like. It permits a fast, simple and reliable visual identification of the respective single structure, i.e., its layer coordinates, in the array (chip). Existing VLSI circuits, such as memory chips, generally comprise a vast number of array cells. For non-automatic testing and for locating physical defects on photomasks or wafers, some of these cells have to be identified by their coordinates. A cell is usually located by counting the bit and the word lines, starting from one corner of the array. As there are very many (several hundred) bit and word lines and only a small section of the array becomes visible under the microscope, such counting is highly error-prone.

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Single-Cell Identification System for VLSI Arrays

The described method is used for single-cell analysis in VLSI structures of memories, gate arrays, and the like. It permits a fast, simple and reliable visual identification of the respective single structure, i.e., its layer coordinates, in the array (chip).

Existing VLSI circuits, such as memory chips, generally comprise a vast number of array cells. For non-automatic testing and for locating physical defects on photomasks or wafers, some of these cells have to be identified by their coordinates. A cell is usually located by counting the bit and the word lines, starting from one corner of the array. As there are very many (several hundred) bit and word lines and only a small section of the array becomes visible under the microscope, such counting is highly error-prone. For word line identification, it would not be problematical to realize alphanumeric structures in the first metal layer. As the array structures in all masks are very dense (up to the first metal layer in existing layouts and up to the second metal layer in future layouts), additional space would be needed between the bit lines for introducing such numbering. As a result, this approach would lose much of its effectiveness. It is therefore proposed that the bit and the word lines be identified by a bar code. For this purpose, every tenth word line is numbered by structures or marks, corresponding to a multi-digit binary number, being associated with the lines...