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SIMS

Technical Concept

Secondary Ion Mass Spectrometry (SIMS) technique uses a beam of energetic primary ions to sputter the sample surface, producing ionized secondary particles that are detected by a mass spectrometer.

Such spectrometer provides electric and magnitude field to bend particle paths. The particles with different masses have distinct bending and thus can be differentiated.In addition, secondary ion intensities and ion sputtering times can be employed to calculate depth profiles of impurities. SIMS has great quantitative sensitivity down to ppm or 10- 6 for element detection.

Nowadays, there are three major SIMS systems：Magnetic-sector, Quadrupole, and Time-of-Flight (TOF).

In addition to CAMECA IMS-6f with high transmission and mass resolution, Ma-tek holds a more advanced SIMS system of CAMECA IMS 7f-Auto, which is powerful in the analysis of high depth resolution, ultra-shallow junction, high throughput, and full automation. This technology, combed with our SIMS database, provides our customers a complete service on surface element analysis.

Application

1．Dopant depth profile

Junction depth and dopant concentration can be characterized precisely.

The most popular application is for Ion implantation species, dosage characterization, and doping concentration profiles of LED (Light Emitting Diode). A SIMS measurement compared with a standard reference provides the depth profile of dopant concentration on material junctions.

2．Analyses of shallow and ultra-shallow junctions

The analysis of shallow and ultra-shallow junctions down to less than 20 nm can be achieved by ion sputtering with low angle and energy.

3．Trace contamination analysis

One of the most important applications of SIMS analysis is surface contamination detection, such as contamination in metal pad in BGA (Ball Grid Array) substrate. Such analysis usually needs a target size larger than 80*80 μm2 based on the size of incident ion beams. Nowadays, surface materials analysis usually relies on SIMS, auger electron spectroscopy (AES), and/or X-ray photoelectron spectroscopy (XPS), also called electron spectroscopy of chemical analysis (ESCA).

4．Metal diffusion analysis

Copper/metal diffusion is a hot topic for advanced IC fabrication technology. It can be understood by the depth profile of metal concentration through SIMS. However, the precision of such profiles is reduced by incident ion implementation, etching and sputtering. Such negative factors can be reduced by back-side instead of front-side SIMS analysis. This technique is useful to study metal diffusion in IC fabrication.

Equipment