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Process Control Monitoring Sampling Methodology

IP.com Disclosure Number: IPCOM000118403D
Original Publication Date: 1997-Jan-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Katayama, M: AUTHOR [+3]

Abstract

The semiconductor production (wafer fab) requires a Process Control Monitoring (PCM) wafer for every major process step to manage its quality. This article describes a PCM sampling methodology to change the sampling rate, 0% to 100% by Manufacturing Execution System (MES). It is a kind of monitor wafer control function in a semiconductor MES.

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Process Control Monitoring Sampling Methodology

      The semiconductor production (wafer fab) requires a Process
Control Monitoring (PCM) wafer for every major process step to manage
its quality.  This article describes a PCM sampling methodology to
change the sampling rate, 0% to 100% by Manufacturing Execution
System (MES).  It is a kind of monitor wafer control function in a
semiconductor MES.

      In many cases, a production lot has a sequential number in its
lot-ID.  A MES or Computer Integrated Manufacturing (CIM) system has
a sampling table and a comparison sub unit following (Fig. 1).  This
is an alternative approach to using a counter for the number of lots
processed.

      Benefits from the sampling system are workload and leadtime
reduction by skipping a PCM wafer merge/split and the measurement.
Also, a sampling system gives an extra capacity to the production
line in the  limited area is of benefit.

      The number of wafers of the non-sampled lot is increased from
24 wafers per lot to 25 wafers per lot from the first process step
through the last process step.  A sampled lot keeps 24 wafers in a
lot in case of 25 slit cassette.  A process flow for application is
shown in  Fig. 2.

      Any digit in a lot ID is applicable if it is in sequence with a
Production start.