A Quick Guide to Mark Optics Wafers

A Quick Guide to Mark Optics Wafers
In 1996 we realized that there was a need for glass and fused silica/quartz wafers that had similar characteristics to high end polished optics. The standard wafers being made were just a commercial polish with not much emphasis on surface quality or surface roughness. Over the years, Mark Optics has worked with numerous research organizations and universities to carefully identify the different requirements of different wafer usage. Using this feedback, Mark Optics has come up with three distinct processes for the fabrication of our wafers. Which one we will use will depend on the collaboration and information the customer provides. We are not a one size fits all organization. Instead, together we make a decision that will ensure wafers that works for you.

Semi-Standard Quartz Wafers:

These are standard quartz (natural); fused silica (synthetic) wafers used primarily for semiconductor process verification and are sometimes referred to as “dummy” wafers. By specifying the surface roughness, this type of wafer is often used in plasma bonding or anodic bonding to silicon wafers (SOQ). . A double side polished wafer typically transmits greater than 90% between 260nm to 2.60 micron and has a refractive index of 1.4585. Surface roughness typically is Ra < 50 Angstrom

Semi-Standard Glass Wafers:

Our borosilicate wafers typically transmit visible through 2.40 micron when a CTE (coefficient of thermal expansion) similar to silicon is desired. These wafers can generally be used in thin film deposition, anodic bonding and as optical aligners to silicon wafers. Refractive indices range from 1.472 – 1.510 depending on material.

Optical Wafers:

These wafers have additional custom processes that have effectively minimized surface defects and sub-surface damage (“micro-cracks” and fractures) that can be introduced during fabrication. They typically have a surface roughness of Ra < 5 angstrom and have shown improved control during dry and wet etching even at nanoscale processing. Optical wafers can be custom made out of any optical glass that is required in your application. We collaborate with you to custom process your wafers to successfully perform in your clean room using your methods.

Fused silica optical wafers allow the maximum transmission from 180nm through 2.60 micron. This is optimal when your application is requiring the lowest light scattering characteristics while performing consistently during etching using standard or non standard MEMS processing.

Glass Optical Wafers can also be manufactured to specifically meet your requirements in performance.

Thin Wafers/Substrates:

Our unique processing capabilities allow us to continue to challenge the physical limitations of thinning wafers. We have successfully polished 1” glass wafers to thicknesses of 25 micron (0.001”) and are working on achieving 15 microns (0.0006”). When necessary, TTV and parallelism can be controlled to +/- 5 microns (0.0002”) or better. We have successfully polished 100mm round wafers to 50 micron thicknesses out of fused silica and Schott Borofloat 33 materials. We are able to polish different shaped substrates as well (squares, hexagons, rectangles etc.). We are here to work with your engineers on these challenging substrates.