Thickness for a Silicon Wafer

A 300mm wafer can be grinded down and polish to a thickness of 2mils without breaking. This is ofcourse with a use of latest state of the art Grinding and Polishing technology.

That would depend on the mechanical and thermal stresses.

I have had the chance though to work with ultra-thin silicon wafers and I can tell you they withstood a surprising amount of wear without breaking. We even dropped them on occasion and they did not break.

So, current wafers are as large as 300mm in diameter and 50 micron thick?

And these wafers are prepared by cutting slices from a polysilicon ingot that are then polished?

It seems like there must be a better/faster/less-expensive way of preparing these wafers!

Mono-silicon, actually. Single-crystal growth and purification are major reasons it needs to start as an ingot. These days, the tolerance requirements on the accuracy of surface planarity and orientation relative to crystal axes is becoming very severe, so the precision of the initial cutting has to be high, and this has to be maintained through the surface preparation stages. I've seen these very uniform wafers etched down to about 50-um. (I'd be interested in references to mechanical thinning of 30-cm wafers to this sort of thickness, as I've no experience of this). Even thinner wafers (in the micron region) can be made using silicon-on-insulator techniques for the starting material, and etching from the back. Depending on the surface properties, these wafers can be very robust, both thermally and against bending; for example, if you don't need specific electrical properties, the wafer can be oxidised or implanted so that the surface is under compression, which will reduce the problem that small surface defects turn into larger cracks.

Fyz

These are the industry standards:

• diameter: 150 mm, thickness: 675 ± 20 μm

• diameter: 200 mm, thickness: 725 ± 20 μm

• diameter: 300 mm , thickness: 775 ± 20 μm

• 400 mm (future) , thickness: 825 ± 20 μm

I hope this will help you.

Abe

I can remember working with 50 mm disks, and I don't remember the thickness. They were making 16 transistor chips, about 2 mm square. Of course, that was 1968. I wish I'd kept one.

RichH