Redesign of a Silicon Wafer Slicing Saw Operator Interface

Design Recommendations

Human Factors Engineering Students, Ken Funk, and Ken Hartman

Department of Industrial and Manufacturing Engineering, Oregon State University

2 September 1996

Table Redesign

• The table (vise top) height was lowered to 34 inches from the floor to comply with NIOSH lifting recommendations.
• The vise opening and ingot mounting block dovetail edges and corners were rounded to reduce the positioning accuracy required to load the ingot.
• The table was extended slightly and the vise length was reduced to 8 inches to allow the ingot to be moved farther from the blade. This gives the operator better accessibility to the vise for loading .

Controller Interface Redesign

• Buttons:
  • Two pairs of buttons were combined into one button:
  • The Cycle Start and Cycle Stop buttons were combined into one Cycle Start/Stop button.
    • The Spindle Start and Spindle Stop buttons were combined into one Spindle Start/Stop button.
    • The two-column numerical key pad was replaced with a numerical keypad conforming to a standard calculator arrangement.
• The keys were enlarged to facilitate operation with gloved hands.
• The overall controller interface layout was changed to group buttons that are frequently operated in sequence.
• The status lights on top of the slicing saw were simplified to two lights:
  • A green steady light to indicate that the saw is in normal operation.
  • A red flashing light to indicate that the operator is required at the saw either to solve a problem or to perform a normal operation such as changing the ingot, changing the cassette, or dressing the blade.
• Screens: The number of screens was reduced to four screens that have all the essential information for the operator to start, to monitor, and to control the wafer slicing process. The four screens are actually half screens: the upper half of the monitor always shows the blade monitoring screen, while the lower half of the screen can change from the setup screen, to the monitoring screen, or to the wafer history screen.
  • Blade Monitoring Screen: This screen is always in the upper half of the monitor and contains the blade speed (rpm), the feed rate (mm/min), the table position (X and Z axes), and blade wobble as measured by three existing sensors located next to the blade surface.
  • Setup Screen: This screen is used to input and to keep all the information that is required to set up the slicing saw when a new ingot is placed on the table: ingot diameter (in), wafer thickness (mm), target blade speed (rpm), slicing rate profile (either constant or variable), slicing rate if constant (mm/min).
  • Monitoring Screen: This screen, along with the blade monitoring screen, contains the main parameters and information related to the blade and the ingot that the operator needs to know to be able to monitor the slicing process: slices remaining (per ingot), length of ingot remaining (in), slices remaining until next blade dressing, and slices remaining until next blade change. This screen has a space reserved in the lower right corner to give warning messages and instructions to the operator such as dress blade or change ingot.
  • Wafer History Screen: This screen contains the information about the blade bow, average feed rate (mm/min) and average blade speed (rpm) for the last 50 wafers sliced. It can be used to control the slicing process or to established if there have been trends in the process during the last 50 wafers sliced.

Controller Arm Redesign

Performance Facilitator