Wafer Stealth Dicing

Accurate Formation of the Modified Layer

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

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

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

Advanced Automation Control

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

System in Motion

Stealth wafer dicing offers a high-precision, high-yield, and completely dry method for wafer die singulation without debris. Nikta Jalayer, Product Marketing Manager at PI, explains why motion subsystems based on air bearing direct drives and piezo systems help tool manufacturers maintain the required performance in tough 24/7 operations.