Browse Prior Art Database

Photoresist Dispense System

IP.com Disclosure Number: IPCOM000115974D
Original Publication Date: 1995-Jul-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 84K

Publishing Venue

IBM

Related People

Seyfert, S: AUTHOR

Abstract

Disclosed is a method for qualification of a precise and highly reproducible photo resist dispense system to reduce the amount of photo resist per wafer. Contrary to the common bellows or membrane type pump systems, a gear drive pump system has been evaluated.

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Photoresist Dispense System

      Disclosed is a method for qualification of a precise and highly
reproducible photo resist dispense system to reduce the amount of
photo resist per wafer.  Contrary to the common bellows or membrane
type pump systems, a gear drive pump system has been evaluated.

The dispense unit of the system consist of following components:
  o  Photoresist container
  o  GATHER gear drive pump system
  o  3-way valve
  o  Millipore filter cartridge
  o  Suck back valve

      The gear drive pump system consists of control unit, motor with
magnetic clutched gear drive pump.  The photoresist dispense volume
is determined by gear width, pump speed and dispense time.  Under
production conditions, start of the pump motor is initiated by
movement of the dispense arm from park to center position.  Motor
ramp up time to 100 rpm is approximately 100 msec.

      Until the real dispense cycle, photoresist is recirculated via
the 3-way valve and the photoresist container.  Syncronized switch on
of 3-way and suck back valve starts the dispense cycle.  At a pump
speed of 100 rpm, approximately 1 ml per second will be dispensed.
Together with optimized resist spin on conditions 2.5 ml photoresist
is sufficient to cover a 200 mm wafer with thickness variations well
below 40 Aengstroms (Nominal resist thickness range .8 - 1.2
microns).

Advantages of this system follow:
  o  Hermetically sealed pump system without vacuum or nitrogen
      requirements
  o  Constant dispense volume over a wide viscosity range
  o  Superior reproducability of dispense volume
  o  Extremly maintenance 'friendly'
  o  Very compact installation
  o  High flexibility, change of resist types including filter change
      well within 30 min possible
  o  Low price

Listed below are qualification results.
  o  Mechanical resist resin damage (shear, compression) - Even under
      100x stress conditions, no change in molecular weight, density
      and viscosity could be observed (see appendix) neither cracking
      of molecular chains nor gel formation has been observed.
  o  Photosensitizer damage - No sensitizer damage did occur through
      above stress conditions.  Evaluations were done on a NIKON B7
      stepper via photospeed tests E0.
  o  Particle & contamination behavior - No particle cumulation could
      be measured over a timeframe of 3 month...