Silicon and Elastomer Coatings

Silicon Coating Characteristics

Thickness, Uniformity and Appearance

  • Uniform dark Silicon color with no visible defects
  • Thickness uniformity better than ▒3%
  • Step coverage >40% one inch below top of vertical wall

RBS Data

  • The films are extremely clean and contain only Si and about 0.1% atomic Ar
  • There are no metallic impurities - no detection of C or O
  • The RBS spectra looks just like bulk Silicon

AFM Data

  • Surface roughness measured at less than 10 nm, grain size 250 - 500 nm.

SIMS Analysis on Aluminum Coupon with 16Ám Silicon

  • Less than 0.5 PPM each for Fe, Ni, Cu, Cr, Mo, Zn, Mg and Al

Density by Cross Section SEM

  • Columnar structure eliminated by high density plasma layered interface
  • Visually 100% as shown by micro cross-section

Adhesion

  • Clear standard Scotch tape and Kapton tape pull test

 

The success of the ion implant process is largely predicated on achieving the highest levels of purity in both isotopic separation of the doping ions, and elimination of potential contaminates from the materials touching or sputtered on to the wafer.

Core offers over 35 engineered elastomers to meet the process requirements of the Integrated Device Manufacturers (IDMs). Elastomers are key to achieving full beam utilization or high beam current without limitations resulting from temperature, contamination and charge -up.

Silicon coatings were introduced in the mid 1990s to cover the Aluminum surfaces exposed to the ion beam. This prevented the sputtering of Aluminum and its contaminating, heavy metal alloying elements on to the wafer. Silicon coatings can extend the life of pre-silicon era disks such as the Varian XP series or Axcelis GSD disks.

 

Elastomers

Since the elastomer is in intimate contact with the backside of the wafer, whatever is transferred from the elastomer to the wafer is processed with the wafer. Even very low levels of heavy metals such as Fe, Cr, and Ni cannot be tolerated. The table shows customer data at levels in many cases approaching detection limits.

PVD Silicon Coating

Core's unique in-house PVD coating system provides a more durable and longer lasting silicon coating compared to OEM flame spray or PECVD coatings. Having the capability on-site eliminates outside vendors which reduces process turn times and provides superior quality control.

Total Reflection X-Ray Fluorescence Surface Analysis of 200mm Wafer Backside

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Near single crystal film morphology vs OEM columnar structure prone to ion beam wear

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SIMS Purity Analysis of Silicon Coating

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SIMS Purity Analysis of Silicon Coating with Al and Fe Contamination

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