Browse Prior Art Database

Area Acquisition Hardware for Pad Inspection on Wafers

IP.com Disclosure Number: IPCOM000061441D
Original Publication Date: 1986-Aug-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 70K

Publishing Venue

IBM

Related People

Chailloux, D: AUTHOR [+2]

Abstract

Some type of simple image processing can be an extraordinarily valuable aid for optical control in integrated circuit manufacturing. Because of its negligible load, non-destructive operation, repetitive reliable and speedy process, it can replace, with distinct advantages, human control of the tasks. Here, the objective is to apply image processing for solder pad inspection on wafers. The volume of these pads must be in a range given by the specifications of fabrication, in order to ensure good soldering between the chip and the substrate, i.e., good contact without making shorts between circuits. Previously published works have shown that there is a mathematical relation between the pad volume and its shadow when lighted with an oblique angle; the pad inspection can be done by inspecting pad shadow.

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Area Acquisition Hardware for Pad Inspection on Wafers

Some type of simple image processing can be an extraordinarily valuable aid for optical control in integrated circuit manufacturing. Because of its negligible load, non-destructive operation, repetitive reliable and speedy process, it can replace, with distinct advantages, human control of the tasks. Here, the objective is to apply image processing for solder pad inspection on wafers. The volume of these pads must be in a range given by the specifications of fabrication, in order to ensure good soldering between the chip and the substrate, i.e., good contact without making shorts between circuits. Previously published works have shown that there is a mathematical relation between the pad volume and its shadow when lighted with an oblique angle; the pad inspection can be done by inspecting pad shadow. An imperative for doing that automatically is to reduce analysis time down to 0.5 second per chip with repeatability and reliability. Repeatability and reliability are functions of the optical and mechanical performances. The speed of analysis is provided by hardware processing of the automaton utilized in this specific control. This article describes a hardware device to process automatically images of pad shadow on wafers. This hardware is composed of two parts: 1.An image generator (blocks 1 and 2), based on the same concept described in the IBM Technical Disclosure Bulletin 28, 673-675 (July 1985), creates a virtual electronic image synchronously with a binary image coming from the sensor. The reference image is composed of successive 32-bit words. Each word gives the following information: data for binary image generation, control bits for pixel counter (block 4) and the pad address in the acquisition memory (block 5). The packed words are arranged as f...