In the production of chips and microchips, individual wafers need to be separated from the wafer. In this process, quality and precision are critical for all subsequent wafer fab production. Therefore, laser slicing has become the preferred slicing technology. One variation of laser slicing is so-called stealth laser slicing (SLD). This involves creating a modified layer within the wafer by focusing a laser below the surface and then using an adhesive sheet expander to separate the chip.
A typical challenge in this type of wafer slicing application is to accurately position the modified layer along both X and Y axes using a system that does not introduce any additional contamination risk to the wafer, achieving the narrowest possible channel, maintaining focus within the wafer, and tracking wafer deformation. Simultaneously, the highest possible scanning speed is required to ensure high processing power. With continuously increasing demand, stealth laser slicing is becoming the preferred choice for high-volume, microelectromechanical systems (MEMS) slicing or smaller, more complex wafers. Accordingly, laser slicing processes also require motion systems that provide high precision and high linearity at high speeds.
Key features of this motion solution
• High yield rate in chip dicing;
• Pollution-free processing;
• Creates a narrow channel width;
• High processing power;
• Will not damage the front and back surfaces;
• High dynamic uniform layer modulation is formed along a predefined cutting line;
• Advanced laser control.
①Z-axis—High Dynamic Laser Focusing Control (P-725 PIFOC Objective Scanner)
• Wear-free, lever-amplified piezoelectric ceramic actuators enable 24/7 operation without generating particles;
• The mechanical design, featuring high rigidity and high resonant frequency, enables high dynamics, short settling time, and high payload capacity for large objectives;
• Up to 800 micrometers of travel, matching wafer thickness;
• Precise positioning with sub-nanometer resolution.
②θX/θY/Z axis – High-precision wafer alignment and positioning (A-523 Z-axis deflection stage)
• Parallel motion design enables wafer adjustment and offset correction in three dimensions;
• Direct-drive linear motor with air bearings enables high-precision leveling;
• The frictionless design with minimal hysteresis provides nanometer-level high repeatability and adjustability;
• Low form factor, easy to integrate;
• Maintenance-free, long service life, 24/7 operation.
③ XY axis – High dynamic wafer scanning motion (A-311 air bearing planar scanner)
• An air-bearing planar scanner with a coreless linear motor enables high-speed, cogging-free scanning with rapid stepping and settling times;
• The contact and wear-free design allows for 24/7 high duty cycle operation with minimal radial runout and nanometer-level straightness and flatness;
• The high-resolution absolute linear encoder option enables fast start-up, reliability, and safety;
• Its low-profile, monolithic design allows for easy integration into system-level solutions, resulting in a compact installation footprint;
• Wide carriages ensure greater rigidity.
Advanced automated control
• The Et h erCAT motion control and drive module provides open network connectivity;
• The laser control interface synchronizes the fixed laser beam with the motion path to achieve high-precision cutting;
• Advanced algorithms like ServoBoost™ provide fast stepping and stabilization, high in-place stability, and excellent constant scan speed;
• NanoPWM™ drive technology reduces tracking errors and optimizes speed;
• Integrated piezoelectric ceramic height axis control synchronized with the wafer scanning axis.
