Wafer Stealth Dicing

Accurate Formation of the Modified Layer

In the production of chips and microchips, it is necessary to separate the individual dies from the wafer. In this process, quality and precision are crucial for all further post-fab operations. Laser dicing has therefore become the preferred dicing technology. One variant of laser dicing is the so-called stealth laser dicing (SLD). This involves creating a modified layer within the wafer by focusing a laser below the surface, and then using a tape expander to separate the chips.

Typical challenges faced by this type of wafer dicing application are to use systems that do not introduce any additional contamination risks to the wafer, to be able to accurately position the modified layer onto both XY axes to enable the narrowest possible streets, and to maintain the focus within the wafer and track wafer distortions. At the same time, the highest possible scanning speed is necessary to ensure high throughput. As requirements continue to increase, stealth laser dicing is becoming the first choice for high-volume, microelectromechanical system (MEMS) dicing, or smaller and more complex dies. Accordingly, laser-dicing processes also demand motion systems offering both high accuracy and a high level of straightness at high velocities.

Key Features of the Motion Solution

High yield in chip singulation
Contamination-free processing
Creation of narrow street width
High throughput
No damaging of front and back surfaces
High-dynamic creation of a uniform layer modulation along predefined cutting lines
Advanced laser control

Z Axis – High-Dynamic Laser Focus Control

  • Wear-free, lever-amplified piezo drives for 24/7 operations without particle generation
  • Mechanical design with high stiffness and high resonant frequencies for high dynamics and short settling times and for high payload of larger objectives
  • Up to 800 μm travel range to match the wafer thickness
  • Fine positioning with subnanometer resolution
    >> P-725 PIFOC® Objective Scanner

θX/θY/Z Axis – High-Precision Wafer Alignment and Positioning

  • Parallel-kinematic design for wafer adjustment and offset corrections in three dimensions
  • Direct drive linear motor with air bearings for high-precision levelling
  • Frictionless design with minimal hysteresis provides high repeatability and adjustments in the nanometer range
  • Low-profile design for easy integration
  • Maintenance-free with long lifetime in 24/7 operations
    >> A-523 Z Tip/Tilt Stage

XY Axis – High-Dynamic Wafer Scanning Motion

  • Air-bearing planar scanner with ironless linear motors for high, cog-free scanning speed and fast stepping and settling times
  • Contact and wear-free design allows 24/7 high duty cycle operations with minimal runout errors and nanometer straightness and flatness
  • High-resolution absolute linear encoder option for fast startup, reliability, and safety
  • Low profile, monolithic design allows easy integration to system level solutions for compact installation space
  • Wide carriage insures increased stiffness
    >> A-311 Air Bearing Planar Scanner

Advanced Automation Control

  • EtherCAT® motion control and drive modules provide open network connectivity
    >> Controller & Drives
  • Laser control interface synchronizes the fixed laser beam to the motion path for high-accuracy cutting
    >> Laser Control Interface
  • Advanced algorithms like ServoBoost™ provide fast step-and-settling, high in-position stability, and exceptional constant scanning velocity
    >> ServoBoost™
  • NanoPWM™ drive technology reduces tracking error and optimizes velocity
    >> NanoPWM™ Drives
  • Integrated piezo height axes control synchronized to wafer scan axes

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