More transistors = smaller chip?

[invidia]

So, I tried searching google, wikipedia, yahoo, etc. and can't really find anything that answers my question. I can't really find a specific answer on the internet. I'm sure most of you in the computer field know of Moore's Law but WHY do we need to make smaller computer chips to fit more transistors? Wouldn't it be better to fit more transistors on a larger chip?

 

[Born2bwire]

Originally posted by: invidia
So, I tried searching google, wikipedia, yahoo, etc. and can't really find anything that answers my question. I can't really find a specific answer on the internet. I'm sure most of you in the computer field know of Moore's Law but WHY do we need to make smaller computer chips to fit more transistors? Wouldn't it be better to fit more transistors on a larger chip?

Moore's law discusses the exponential growth of the number of transistors. You can't sustain this exponential growth by keeping your fab size the same.

 

[SoftwareEng]

more area = longer paths for signals to travel, i.e. slower and hotter. also, smaller = cheaper to make b/c they can print more chips per silicon board.

 

[jdobratz]

Chips using a smaller manufacturing process usually run cooler then their larger counterparts. So, you can put more transistors on a smaller chip and not have a chip with a ridiculous thermal output.

 

[AsianriceX]

One reason:
Cost. If you can shrink down the die, you can fit more dies on a silicon wafer.

More dies = higher chance for good yield + profit

 

[Jeff7]

Originally posted by: SoftwareEng
more area = longer paths for signals to travel, i.e. slower and hotter. also, smaller = cheaper to make b/c they can print more chips per silicon board.

And I'll counter what may be the next question - Why worry about not using up silicon? Isn't silicon everywhere?

Sure it is. It's really common.
Problem: it's dirty. CPU's need really pure silicon, and the refining process is what makes cheap, abundant silicon so expensive.
Kind of like titanium - it's also really common in nature. The problem is getting pure titanium. That's what makes it as expensive as it is.

 

[Gibson486]

You do not NEED a smaller chip to fit more transistors. The thing you want to do is fit as much as the transistprs as close as possible. Why ?

1. It makes heat come from 1 centralized spot, thus you need a cheaper cooling solution.

2. Timing. The closer the transistors are, the better the timing between the two (obvioulsy, the longer they are from each other, the longer it takes the signal t get there) .

3. People just want smaller things.

4. price. smaller is cheaper.

 

[invidia]

So the smaller chip agrument is just for cheaper costs?

 

[her209]

Silicon is expensive. Silicone too!

 

[Atheus]

Originally posted by: invidia
So the smaller chip agrument is just for cheaper costs?

And to physically fit the thing in your case... if an Opteron was built on the 80486 process this would likely not be possible.

Plus:

Originally posted by: SoftwareEng
more area = longer paths for signals to travel, i.e. slower and hotter.

 

[PottedMeat]

If you have a wafer say 12" in diameter and can fit 300 microprocessors and sell each one for $50 but you shrink the transistors and therefore each microprocessor and can now fit 600 on a single wafer and sell each one at the same price would you do it?

Discounting any difficulties in the die shrink and poor yields of course.

 

[Gibson486]

Originally posted by: invidia
So the smaller chip agrument is just for cheaper costs?

no, you just want smaller chips. think about....if you have 1 million transitors and you do not bother to shrink the die size, you are gonna end up with one big chip.

 

[dullard]

Originally posted by: invidia
So the smaller chip agrument is just for cheaper costs?

That is mostly it.

1) Smaller chips = more products per silicon wafer. That means with the same materials cost, the same labor, the same machine time, you get more chips. For example, moving from .35 micron sizes to .25 micron sizes means you get double the number of chips per wafer (I know it isn't exactly double but lets not complicate things). Going from .25 micron to .18 microns gives you another double. Going from .18 to .13 doubles it again. In the end you get 8 times as many of the same chip. Thus, costs are 1/8th the cost of a large chip. When we are talking about a $50+ CPU, 8 times the price is a big deal.

2) Errors. There are flaws in the chip manufacturing process. The flaws will be fairly randomly distributed (I know there is a bias towards the outer edges, but lets not complicate things). If you have a small chip, the chance of a flaw being on the chip is small. If you have a very large chip, the chance of there being of a flaw on the chip is astronomical. Basically, if the chip is too large, you'll be virtually guaranteed an error somewhere. An error which may very likely make the chip unusable. If the chip is too large, you throw away a ton of chips because they don't work. Take that 8x the cost and make it much higher.

3) Geometry. Chips are roughly rectangular. Silicon is a circle. Try taking out a piece of paper and draw it. Draw a circle. Put several large rectangles inside it. Put as many large rectangles as you can. See all the waste along the circle perimeter? That is wasted materials, wasted labor, and wasted machine time. Try it again with small rectangles. See how the waste is drastically smaller? Take that 8x the cost for a chip and make it much higher due to waste.

The rest is just user friendliness. You don't want that IPod nano to be the size of a football do you?

 

[RichUK]

The greater and more advanced the processor logic, generally constitutes to a higher number of transistors required. Especially when you increase the amount of on die L2 cache too.

It benefits AMD/Intel to manufacture on smaller nodes, because of the obvious benefit of fitting more dies on each wafer.

The smaller the manufacturing process, also allows for a lower TDP.

 

[SludgeFactory]

Originally posted by: invidia
So the smaller chip agrument is just for cheaper costs?

With all the processing steps involved in going from a silicon boule to a finished die, there's a big amount of $$$$ invested there. They absolutely want to squeeze every last chip out of a hunk of silicon that they can.

And it gives you a smaller die to have to package and carry around in your portable devices.

 

[RichUK]

Originally posted by: SludgeFactory

Originally posted by: invidia
So the smaller chip agrument is just for cheaper costs?

With all the processing steps involved in going from a silicon boule to a finished die, there's a big amount of $$$$ invested there. They absolutely want to squeeze every last chip out of a hunk of silicon that they can.

And it gives you a smaller die to have to package and carry around in your portable devices.

True, it would be very advantageous if the wafers were actually somewhat rectangular.

However the wafers are circular when sliced from the silicon ingot.

 

[SludgeFactory]

Originally posted by: RichUK
True, it would be very advantageous if the wafers were actually somewhat rectangular.

However the wafers are circular when sliced from the silicon ingot.

I don't see where I indicated they weren't.

 

[RichUK]

Originally posted by: SludgeFactory

Originally posted by: RichUK
True, it would be very advantageous if the wafers were actually somewhat rectangular.

However the wafers are circular when sliced from the silicon ingot.

I don't see where I indicated they weren't.

Huh, i was simply agreeing with your previous statement:

They absolutely want to squeeze every last chip out of a hunk of silicon that they can

I was basically saying. If they could produce rectangular wafers, then the wasted silicon could be greatly decreased. However, as we know, due to the way silicon ingots are manufactured, this is not possible.

 

[OrganizedChaos]

chip makers are shrinking there products down as fast as they can and theres still not enough polysilicon to go around.

 

[SludgeFactory]

Originally posted by: RichUK
I was basically saying. If they could produce rectangular wafers, then the wasted silicon could be greatly decreased. However, as we know, due to the way silicon ingots are manufactured, this is not possible.

ah, I misunderstood