Author: Dann Corbit
Date: 15:58:09 02/28/03
Go up one level in this thread
On February 26, 2003 at 12:03:42, Steve J wrote: >>5. I am also looking for some predictions/information about processor speed in >>20-30 years from now. For micro's Moore's law still holds. So 21 years is 7 >>doublings of speed or 128 times as fast as today. > > > I've spent 25 years in manufacturing side of the semiconductor industry and >would like to introduce what I call "No-Moore's Law". It describes the physical >limitations that silicon (or any other compound) will run out of gas and can be >shrunk no more. It also talks about some of the financial limitations of >shrinking die. > > There are several key points. 1) There are physical limitations to what >degree a transistor size can be shrunk. This is based on the size of the atom, >and 2) There are exponential increases in the costs of fabs and mask sets as >each reduction takes place. These will cause a practical end to the amount that >die sizes can be shrunk. > > > First, let's take a look at the existing "90 nanometer" process. The >operations of the circuits relies on tightly controlled processes. While the >circuits and processes are controlled very tightly, a 10% mismatch between >components on a given die can be fatal. > The size of a silicon atom is .3 nanometers. This means that existing >processes are about 300 atoms across. At this size, a one atom variance is .3%. > However, if the transistor size is halved, for example, five time, then it will >be 300/(2^5) =~ 10 atoms across. This means only one atom variance will cause a >mismatch of 10%! Added to that is normal processing variance which will makes >the product not manufacturable. > If we assume that the size is halved every two years, then there is about 10 >years left in Moore's law. > > > Compounding the problem is the exponential cost of making fabrication lines of >finer size transistors. From a historical perspective, 25 years ago it cost >under 10 Million dollars to put together a fab (equipment, extra cost for a >clean environment, etc). EACH product that was made in a fab would have a >dedicated mask set as tooling to make the product in that fab. This tooling >cost in the range of $10k to $15k. > At that time not only did every company, but, every product line within a >company that had more than $50 Million in sales would have their own fab line. >Many companies would have 6 to 8 (or more) fab lines. > The costs of leading edge processes have increase dramatically. There are no >more $10 Million fabs being made. Many new fabs are costing $1 Billion or more! > This has caused a dramatic shift in fab investments. Not too surprisingly, >very few companies can afford to make a leading edge fab, and instead, rely on >companies like TSMC and UMC to make the large investments and allocate the cost >into the costs into the sales price of the wafers. > While this has provided a working business model, as the cost of fabs continue >to double, there will be a point at which the incremental savings from a new >process technology will be too expensive to justify the cost of the fab. > > The mask set tooling has also increased dramatically. Instead of $10k to $15k >dollars for a set, maturing processes of today cost $100k. Products that are in >design right now are forecasted to have mask set tooling costs in excess of >$500k. Given that the entire annual budget for smaller companies (including >salaries, rent, etc) can be $5 Million, it will not take long before fewer and >fewer companies will be able to make a run at the market with new products. > > > The bottom line is that physical and financial constraint will bring an end to >Moore's law. Realistically, it will not be an abrupt halt, but, instead from >doubling every two years, to double every four years, then to 5% increase per >year. > My bet is that we will see a dramatic slowing in 7 to 10 years. > Beyond that, we will rely increasingly on more processors per system and other >techniques instead of more transistors per processor die. It's not the CPU speed we need to worry about. It's the memory bandwidth. Memory speed increases only linearly, while CPU speeds tend to increase exponentially. It has already become a significant problem. Unless a breakthrough occurs, the speed of the CPU will at some point become irrelevant, because the memory cannot possibly feed it fast enough.
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