The Shim Spinning System is a family of templates designed to handle all types of materials from germanium, quartz and silicon to sapphire and silicon carbide. There are two types of templates that are used in the shim spinning system. The standard template and the CIG version.
There are two of templates styles will accept any of three shim spinning systems, the shim and insert (S3), the ShimSert (SS) and the PadSert (PS) systems. Each system has unique advantages.
The Shim Spinning Systems were developed to provide a more even stock removal or final polish. Wafers held fixed in the template have a higher surface velocity at the outer diameter of the template and typically see a higher removal rate at the OD and lower at the inner diameter. This typically affects flatness, bow, warp and TTV.
By allowing the wafer to rotate in the pocket, the material removal is more even across the surface. This provides a flatter part with lower bow, warp and TTV.
The difference in the templates is that the template on the right above has grooves machined into the surface that routes the slurry onto the wafer surface. These are called Chemical Introducing Grooves or CIG. Rather than having the slurry simply pressed off of the surface, these grooves route the slurry directly to the wafer.
CIG allows a lower slurry flow to achieve the same level of polishing performance which is highly advantageous in applications that use some of the more expensive slurry formulations.
Note that both of these templates use a clear PET backing and pocket depth adjustment shim and a special grade of translucent G-10 frame material. This is done so that the user can easily see that there are no trapped air pockets when they mount the template to the carrier or polishing head.
S3 (Shim Spinning System)
This system is comprised of three components, the template, a spacer shim and a poromeric insert. The template pocket depth is set at the factory so that a thin shim and the poromeric insert provide the proper wafer protrusion.
The poromeric insert will compress over time but, rather than replace this expensive component, we replace the shim with a thicker one. This returns the wafer exposure to the proper value and extends the life of the template and insert material.
Typically the S3 tool uses a set of three shims to extend the life of the poromeric insert, increase productivity and provide a higher return on the purchase of the S3 tool with longer tool life and greater throughput.
SS (ShimSert System)
This system was developed as a direct replacement for the S3 system. Based on some clients difficulty handling the individual shims and inserts, this system combines the two into a single piece with the poromeric insert material bonded to the shim.
An advantage to the ShimSerts is that they can be constructed to specific contour requirements. ZeroMicron has worked with clients to limit edge roll-off and limit the Edge Exclusion (EE) zone as well as correct bow on larger wafer sizes.
PS (PadSert System)
PadSerts require a template with deeper pockets to accommodate the thicker structure of the polishing pad and poromeric insert material. The PadSert system was developed to specifically answer a need for a polishing template that could withstand long polishing cycles under heavy pressure.
PadSerts have been tested at the upper limits of pressure on many tools and run for extended periods of time at high temperature. The pad material continues to rotate under the most adverse conditions providing an even finish to the wafer.
The PadSerts can be produced with special features such as concave or convex surfaces to correct for bow or extend the usable surface area and limit the Edge Exclusion zone.