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Heat Pulse Resistor Trimming Method

IP.com Disclosure Number: IPCOM000108870D
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 1 page(s) / 39K

Publishing Venue

IBM

Related People

El-Kareh, B: AUTHOR [+4]

Abstract

By applying thermal annealing pulses of appropriate temperature and duration, arsenic doped polysilicon resistors can be adjusted to a higher or lower resistance value. This adjustment may be performed by rapid thermal annealing (RTA) all resistors in integrated circuits on a completed wafer after resistance measurements on kerf resistors or by focused heat input to individual resistors.

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Heat Pulse Resistor Trimming Method

      By applying thermal annealing pulses of appropriate temperature
and duration, arsenic doped polysilicon resistors can be adjusted to
a higher or lower resistance value.  This adjustment may be performed
by rapid thermal annealing (RTA) all resistors in integrated circuits
on a completed wafer after resistance measurements on kerf resistors
or by focused heat input to individual resistors.

      After conventional processing to form integrated circuits on a
silicon wafer and all of the attendant elevated temperature
treatments, sample transistors in kerf regions of the wafer are
measured.  If resistance values are found to be lower than desired, a
relatively low temperature (e.g., 700 degree Celsius heat pulse)
applied for time durations in the tens of seconds range increases
resistance values.  To decrease resistance values, thermal pulses in
the 1000-degree range having shorter duration up to 10 seconds are
used.  The treatments to increase and/or decrease resistance values
may be repeated.

      After these RTA treatments, sheet resistivity of all resistors
on a wafer is found to be in a narrower range than before any RTA
treatments.

      RTA pulse temperature and duration ranges described are
compatible with a conventional BIFET technology, i.e., active device
parameters are not changed.

      Disclosed anonymously.