Vendor viewpoint
Determine Reflectance, Film Thickness and Refractive Index with NanoCalc-XR
Figure 4: PlasmaPro NGP1000 etch system
are achieved with high plasma densities. This translates as a clamping issue for single wafers and is typically approached using an electrostatic clamp. A dielectric hard mask can be used and this opens the possibility of high etch rate batch processing where uniformity across the batch dictates the yield.
Photonic crystal patterning
By patterning the light emitting surface of the HBLED with a quasi- crystalline array known as a photonic crystal it is possible to improve light extraction. An extreme demonstration of this is shown in Figure 3 where a 600nm feature has been etched 4µm deep giving a >6:1 high aspect ratio structure. Here the challenges are maintaining the vertical profile in the etch feature in order to ensure the optical performance of the photonic crystal.
Equipment
In order to achieve the high etch rates and low damage requirements the industry has developed several high density plasma sources: Inductively Couple Plasma (ICP);Transformer Coupled Plasma (TCP); High Density Plasma (HDP) . All technologies offer a driven table on which the sample sits and a separate plasma source which enables high plasma densities without an increase in the DC Bias seen by the sample. DC Bias has been shown to increase plasma damage to sensitive surfaces so this is an essential system characteristic. The PlasmaPro NGP1000 etch system, designed for GaN, AlGaInP and Sapphire etch, offers batch sizes up to 55 x 2”, 13 x 4”, 5 x 6” or 3 x 8”, yielding market leading volumes of wafers/month. The HDP Etch plasma source achieves comparable plasma densities to ICP sources, maintaining the benefits of high etch rates and low damage. Other key technologies required for etching batches are: a knowledge and control of plasma uniformity over large areas and the capability to control the sample temperature of multiple wafers under aggressive plasma conditions.
This work is supported by the European Commission (FP7 contract No. 228999: “SMASH”)
© 2011 Angel Business Communications. Permission required.
» Wavelength range 250 – 1050 nm » For layers from 10 nm up to 100 µm » Measure up to 10 layers
» Film thickness of transparent or semitransparent materials
Want to know the thickness of your coating? Contact us today!
www.oceanoptics.eu thinfilm@oceanoptics.eu Tel: +49 711 341696-0
November/December 2011
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