Electroless UBM Formation Service
As semiconductor packaging technology achieves greater miniaturization and integration, flip chip bonding is increasingly taking over from wire bonding as the bonding method used for LSI, IC, and other chips. In flip chip bonding, under bump metallurgy (UBM) formation to bond the metal pad to the solder is viewed as essential. Our company's UBM processing employs electroless plating to offer lower costs, shorter delivery times, and greater miniaturization, and offers the added advantage of being an environmentally friendly technology. We also offer solder bumping for the UBM-formed wafer, affording customers an all-in-one processing service from UBM formation to bumping.
Specifications
Design Rules
| Description | Specification | (Trial production) |
|---|---|---|
| Wafer | Si, GaAs | Si, GaAs + SiC |
| Wafer size | 50-300mm φ (2"-12") | As on the left |
| Wafer thickness | ≧150μm | Min 80μm (6"φ) |
| Bond pad metal | Al, AlSi, AlCu, AlSiCu, Cu, Au | As on the left |
| Passivation opening | ≧60μm | Min 4μm |
| Applications | Logic, Memory, Image sensor, Power device, and any others | |
| UBM | E-less Ni/Au, E-less Ni/Pd/Au (Pb-free, CN-free bath) |
| Ni (material) | Ni (P 5–10%) |
|---|---|
| Ni thickness | 1-10μm |
| Pd thickness | 0.05-0.2μm |
| Au thickness | 0.03-0.2μm |
| Thickness uniformity | ±10% (200mm φ wafer) |
Fully Automatic Electroless UBM Production Line
- *Clean Room:Class 1000
- *Plating Lines are located in Japan and Taiwan.
Features of our electroless plating process
- Uses self-developed plating process and equipment
- Provides a reliable quality control system using the Company's own analysis equipment
Plating chemicals and films are analyzed in-house to meet customers' requirements and to improve the plating quality - Achieves high processing capacity of over 20,000 wafers/month
- Capable of protecting the backside of wafers from damage
Inspection Tools
Analytical Tools for Electroless Plating
| Surface morphology | FIB-SEM, FE-SEM, SPM |
|---|---|
| Elemental analysis | FE-EPMA, FE-AES, XPS |
| Functional group analysis | Raman, FT-IR, UV |
| Crystal structure analysis | XRD |
High Film Quality (1) … Highly uniform plating on pads with differences in electrical potential
Our plating process delivers uniform quality of UBM, even for pads with differences in electrical potential or size.
High film quality (2) … Fine and uniform Au deposition without pitting corrosion
The grain structure of our new cyanide-free Au is fine and uniform. It inhibits pinholes and pitting corrosion.
SEM images of the Au and Ni surfaces after gold stripping
