Micromachining Applications

High-precision, high-repeatability drilling is achieved using one of two methods
 (depending on the application requirements):

One hole at a time, drilling at a high repetition rate

Parallel processing multiple nozzles per step and repeat using high energy
 excimer lasers with special telecentric lenses and beam shaping homogenizers

IPG Microsystems has developed unique drilling methods resulting in low-cost, high-volume processes where nozzle arrays up to 2 cm long can be processed in each step-and-repeat with high accuracy and low telecentric errors with controlled hole cross sections.

Drilling accuracy is better than ±0.5 micron hole-to-hole tolerances with telecentric holes to better than ten arc seconds. Laser drilling offers controlled taper angle processing, generation of hydrodynamic shaped nozzles or low taper angle nozzles. Special tooling is available.

IPG Microsystems has developed three different hole-drilling techniques for high precision and high speed nozzle plate fabrication. Each application has advantages for different types of materials and nozzle design.

For example, one technique allows the generation of high precision ±0.5 micron holes with sculpted 3-D nozzle shapes. Ink fluid channel formation and integrated rock trap filters are also achievable with the 3-D micromachining process.

For high power blue LEDs, GaN (gallium nitride) or InGaN (indium gallium nitride) semiconductor material is grown on a sapphire substrate. To remove or ‘Lift-off’ the semiconductor from the sapphire, a high intensity laser beam is directed through the sapphire and aimed at the GaN. This creates a shockwave at the interface disassociating the GaN from the sapphire.

The principle of UV LLO is the different absorption of UV light by GaN and sapphire. GaN, with a bandgap of ~3.4eV, strongly absorbs 248 nm radiation (5eV), while sapphire is a poor UV absorber due to its high bandgap energy (9.9eV). An excimer laser is employed due to its high UV pulse energy, typically 1J/cm² on target with large area illumination, 1mm²-5mm². The LLO process is also used on LED wafers with AlN (aluminum nitride) and AlGaN materials.

The process creates free-standing GaN films and integrates GaN LEDs onto virtually any substrate. Additionally, this technique increases LED light output and has low operating costs due to high throughput capability whereby multiple die are exposed by a single pulse.

Innovative beam homogenization and synchronized high speed stage motion laser triggering (“fire-on-the-fly”) techniques allow high yield LED LLO at ambient temperature, with running times shorter than 1 min/ 2" diameter wafer. The same technique is also used for AlN lift-off, OLEDs and for transferring other thin films.