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Determining Wafer Defect Density at any Subsector Operation

IP.com Disclosure Number: IPCOM000082643D
Original Publication Date: 1975-Jan-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Levine, JE: AUTHOR [+2]

Abstract

This method is designed to determine defects added to a processed wafer during any sector or subsector. Fig. 1 shows pinhole defects 4 and 6, respectively, both above and below the wafer surface. The wafer consists of photoresist 8, metal (Al) 10, quartz 12, and silicon 14. After etching the wafer (Fig. 2), only the pinhole area 4 etches away. The wafer is then irradiated (see Fig. 3) with an infrared light source 16 and a sensor 18, which passes through Si but not metal. The sensor 18 scans for pinholes; however, below the surface pinhole defect 6 is not sensed.

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Determining Wafer Defect Density at any Subsector Operation

This method is designed to determine defects added to a processed wafer during any sector or subsector. Fig. 1 shows pinhole defects 4 and 6, respectively, both above and below the wafer surface. The wafer consists of photoresist 8, metal (Al) 10, quartz 12, and silicon 14. After etching the wafer (Fig. 2), only the pinhole area 4 etches away. The wafer is then irradiated (see Fig. 3) with an infrared light source 16 and a sensor 18, which passes through Si but not metal. The sensor 18 scans for pinholes; however, below the surface pinhole defect 6 is not sensed.

An "island pattern" is then exposed (see Figs. 4 and 5), developed, and etched on the wafer in order to isolate the metal areas, except for those under the surface defects 6 that connect the metal 10 to Si 14. Fig. 6 shows how the striped wafer is anodically etched. Since only those metal islands that are connected to the Si through the defect path 6 in the quartz 12 will oxidize, the colored oxidized regions are easily detected either visually or through automatic testing.

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