LED Materials Analysis & Device Testing

Cs-Corrected Transmission Electron Microscopy (Cs-TEM)

Energy Dispersive Spectroscopy (EDS)

Electron Energy Loss Spectroscopy (EELS)

As LED device includes complicate nano-scale thin film structure, TEM/EDS/EELS is a critical technique for quality control and failure analysis of the device. Outermost Technology has established service line for LED sample analysis, and recently selected as a high volume service provider from a world class LED manufacturer.

Atomic Force Microscope (AFM)

Conductive AFM (c-AFM)

Scanning Capacitance Microscope (SCM)

Scanning Spread Resistance Microscope (SSRM)

c-AFM, SCM, and SSRM are all based on the AFM technology. With c-AFM, contact quality of metal electrodes to GaN can be analyzed through I-V curve. SCM shows active carrier distribution with operation bias applied. And SSRM shows the quantitative resistivity value which can be very useful in the development of new GaN materials. Use the pic below on its left side space.

Principal Component Analysis with Time-of-Flight Secondary Ion Mass Spectrometry (PCA ToF-SIMS)

PCA is an orthogonal transformation to convert a set of observations of possibly correlated variables into principal components. The PCA-ToF SIMS can be widely used for the materials identification or mapping of polymers (in LED application) and other organic or bio materials.

Positron Annihilation Lifetime Spectroscopy (PALS)

Doppler Broadening Spectroscopy (DBS)

PALS/DBS is a non-destructive spectroscopy technique to study voids and defects in solids. These techniques can identify the defect type and the defect distribution along the film depth, which is an ideal metrology for the LED industry.

LED Reliability Test Sequence

The unique inclusion of functional tests in the sequence addresses time-zero requirements as those tests are done at the same location as environmental tests by using an integrated sphere. Luminous flux evaluates the decrease in light output of a bulb that occurs over time during the environmental tests.

LED Failure Analysis

Typical Testing Sequence for Leakage Failure

• Curve tracing for leakage check
• EMMI analysis for fault localization
• Decapsulation and delayering
• Scope or SEM inspection

Typical Testing Sequence for Open Failure

• Curve tracing for open check
• X-ray or 3D-CT for wire bonding/adhesive area check
• If no defect on wire bonding
  
  • Cross-section for adhesive
  • Scope or SEM inspection