Random thought about Wafer making

[Poohy14]

So, In class last week in my Electronics class  we were talking about wafer making and the process. I got a little curious on why they make wafers round instead of square or another shape. I asked my teacher and he didn't know but he said "maybe it was the way they carried it, made it easier to hold on to." I just want to know if why it is round because it is driving me insane in the brain.

 

 

 

 

 

Edit: if it was square you could save more processor or other parts from being cut off and save more money

 

Here is the process for making a wafer, Is it just easier to cut if its round??

[Jvagle875]

Because they are rotated so a round circle is what you get.

[cramved]

I think the process involved in making them involves spinning therefore making it a circle.

[Glenwing]

Creating the wafer is done by spinning it at high speed, the process is required for the purity/lack of defects that is necessary for creating ICs out of them.

[Poohy14]

Creating the wafer is done by spinning it at high speed, the process is required for the purity/lack of defects that is necessary for creating ICs out of them.

 

Do you have to spin it for the process to work and why do they have to spin it??

[MrSuperb]

 

The ultra-pure silicon for wafers is grown in huge round rods that

are then sliced into wafers. The round shape comes naturally with

the growth process. Making the slices square-shaped would be more

work and waste material.

The yield is lower near the edge of the wafer, because it is more

difficult to control processes there. A circle has the lowest edge-

to-area-ratio of all shapes and thus offers the highest possible

yield. Some of the processes in a wafer fab, e.g. coating with

photoresist by dripping on a spinning wafer, even make use of the

round shape for process uniformity and would not work well with

square wafers.

Greetings from Singapore,

Frank Berauer

 

from http://www.madsci.org/posts/archives/1998-10/909739239.Cs.r.html

[Glenwing]

Do you have to spin it for the process to work and why do they have to spin it??

 

The spinning process is what gives it the uniformity which is why they use it instead of polishing it with a different method or (for example) just pouring into a square mould or something, there would be too many defects.