Hacker News Reader

Comment by kowalski7cc | Hacker News Reader

Why not hexagons?

Good for tessellation only if chips are also hexagons. Arguably chips themselves could be hexagons for better pin density and potentially thermal properties. Surprised nobody has tried this before.

You cannot cut straight lines trough hexagons. Triangles would work but would be even more inconvenient to design cut and process into normal chips. So squares it is.

Water jet cutters or EDM cutters could both be used on silicon and there is no need for either to cut straight lines.

When silicon area is expensive and performance can be maximised by reducing average on-die wire length, hexagons sound like they might make sense.

Obviously current layout tools prefer X-Y area splits, so a lot of tooling would have to be redesigned to make use of a probably rather small performance gain.

> Water jet cutters or EDM cutters could both be used on silicon

Wouldn’t they contaminate the just fabbed silicon surfaces? (That being said i have no idea how swarf is typically managed in die cutting.)

It isn’t a question of cutting at an angle, it is a question of cutting in a specific direction all the way across the water. Hexagons demand that you change directions multiple times while cutting at chip level precision across a wafer you are trying to hold in place with the same amount of accuracy.

The cutting accuracy can be really low compared to everything else - 100um accuracy is fine, and even a hobby level CNC machine can do that.

No you can't. Anyone whose spent any time breaking glass into specific shapes knows how difficult it is. Glass can't handle the force required to break it in one go. Multiple perfect passes have to be made in order to do it with reasonable yield. Having corners inside your fault lines is asking for trouble. Chips arent that much different.

This is silicon we're talking about... It can easily be cut with a wire saw, and while that is usually in a straight line, it doesn't need to be.

You could with plasma/chemical dicing, and people have

But it breaks too much of the existing flow to be worthwhile

Hexagons are the bestagons

Rectangles are straight up simpler :)

So how about a compromise and get interlocking triangles?

i enjoyed that cgp grey video so much i rewatch it every few months

I'm not sure how chips are cut from a wafer, but long straight cuts can be used for a grid. If it's more like laser cutting via CNC then shape might not matter.

I’d imagine most things are designed in rectangular constraints

Reply on news.ycombinator.com