Semiconductor & Nanotech

Wafer Level Packaging

Wafer Level Packaging

Bruker has a range of systems for wafer level packaging. Composition measurements on individual bumps and thickness of under-bump metals can be realized using micro-XRF.

RDL and Bumps

Semiconductor manufacturers face many key emerging trends in Wafer Level Packaging. These include:

  • Redistribution Layers
  • New UBM Films and Stacks
  • Tighter Pitch Features
  • Smaller Solder Balls
  • Lead-Free Solder Alternatives

These critical trends create associated metrology challenges, and generate the need for:

  • Thickness and composition control
  • High sampling and high throughput
  • Fewer blanket wafers
  • Production wafer sampling

These needs drive the demand for non-destructive thickness measurements on RDL and UBM layers that include a small spot measurement technique with excellent spot placement, with tighter pitch densities (<200μm), and smaller solder balls (<100μm).

Other key considerations are composition measurements on the bulk UBM layer, where Ni(P) composition impacts the quality of the passivation layer, and composition measurements of lead-free solder alternatives:

  • Sn/Ag composition → impacts reliability / prevents “shorts”
  • Sn/Ag has shown to gain Ni or Cu from the UBM during the reflow process

XRF technology from Bruker answers these challenges via energy dispersive (~150eV) techniques with multi-detector array for fast, high-throughput measurements and 100% detector efficiency for Sn/Ag, plus small spot (poly-capillary) optics capable of measuring down to 50×50μm features. In addition, Jordan Valley XRF technology offers non-destructive real-time measurements that deliver immediate turn around.