In 1971, Intel released the first microprocessor 4004, it uses 10 micron craft production, only contains more than 2300 transistors, and today, 45 years after, Intel now the largest is codenamed Knights landing, a new generation of Xeon Phi processor, 14nm manufacturing process, core area of more than 700mm2, with 72 million transistors, with astonishing 76 x86 cores and paired with 16GB MCDRAM cache. Now the CPU can become so large, of course, due to the development of semiconductor technology.
Knights Landing 14nm processor with 76 core
Mastery of the semiconductor process not only affects the complexity of the CPU, but also affects the company's fate. Intel processor has already entered the 14nm process node, amd FX processor still stays in the 32nm process to know years ago, AMD and Intel in semiconductor technology gap is not so big now, because before amd also have their own fabs, process control in their own hands, has now become a fabless companies and technology progress depends on Globalfoundries or TSMC foundries. Today our super class will be to discuss this problem, advanced semiconductor technology in the end can bring what influence it?
Speaking from Moore
Intel progress in semiconductor technology is expected
According to the development trend of Moore's law, the transistor gate pitch every two years will be reduced to 0.7 times, in 1971 launched 10 m processor, through the 6 m, 3 m, 1 m, 0.5 m, 0.35, 0.25 m, 0.18 m, 0.13 m, 90nm and 65nm and 45nm, 32nm and 22nm and now the 14nm, semiconductor manufacturing process is becoming smaller and smaller, and in so doing, what are the benefits?
Advantages of one: the smaller the process will be able to plug more transistors, cost down
CPU production is needed after seven processes, it is respectively: silicon purification, wafer cutting, photocopying, etching, repetition, stratification, packaging, testing, and the etching process is the important work of the CPU production is anew technology, simple etching is to use a laser in the process of silicon wafer manufacturing transistor and the etching process is completed by the light, so for the etching of the light wavelength that is the key to enhance the technology, it affects on the silicon wafer etching of the minimum size, is also the linewidth.
Now the semiconductor technology has said how much nm technology is actually refers to the linewidth and is chip on the most basic function unit gate width, because in fact the door circuit connection between the width of the biconditional gate circuit is equal to the width of a, so the line width can describe the manufacturing process. Narrowing the line width means that the transistor can be made smaller and denser, and with the same chip complexity, smaller wafers can be used, so the cost is reduced.
Intel the cost of different process technology, the core area of evolutionary Roadmap
Advantages of two: the frequency is higher, the voltage is lower
More advanced semiconductor manufacturing process is another important advantage is that it can improve the operating frequency, reduce the spacing between the elements and the capacitance between the transistors will be reduced, the switching frequency of the transistors can be improved, thus the working frequency of the chip will go up.
Also transistor size will reduce their resistance, the desired turn-on voltage will decrease, which represents the CPU working voltage will decrease, so we see each a new CPU core and the voltage over the previous generation products are reduced accordingly. In addition, the dynamic power loss of CPU is proportional to the square of the voltage, the operating voltage is reduced, so that their power is also greatly reduced.
Obstacle to process upgrade: leakage current
However, the semiconductor process is not possible to reduce the limit of the process, the leakage current is an important factor in this problem. Field effect transistor gate and channel between an insulating layer of silicon dioxide, role is to prevent the leakage current of the insulation layer is thicker insulation effect better. However, with the development of technology, this insulated layer thickness is slowly cut, originally only a few atomic layer thick silica insulating layers become thinner and causing it to leak more current, subsequent leakage current added additional chip power consumption.
The traditional technology of the transistor (left) and 3D transistor (right) model contrast, black part is the insulation layer
To solve the leakage current the problem and continue to follow the previous process is not possible, 2007 Intel in the 45nm node introduced HKMG technology, and in the 2011 Intel in the 22nm node to import the 3D transistor is FinFET technology. Both of them can be effectively reduce the leakage rate.
3D 22nm transistor than the 32nm process greatly reduces the leakage current
At the same time, researchers have begun to look for new semiconductor materials, including GaAs, carbon nanotubes and even quantum wells. 2015 IBM and partner Samsung, Globalfoundries demonstrates for the first 7 nm chip technology, is the use of silicon germanium material, using the material of the transistor switching speed faster, lower power consumption and higher density can easily achieve 200 billion transistor, transistor density than the existing silicon-based semiconductor higher one order of magnitude.
Process upgrades to increase power density?
Also in the 2012 Intel released 22nm Ivy bridge, we have found that this processor than on a sandy bridge temperature to high considerable that explanation is IVB core area decreased and transistor density increases, so power density than the SNB is higher, and the contact area due to reduced heat dissipation efficiency decreased. It sounds reasonable but also lead to IVB high temperature and not the.
SNB has been fluxless solder (fluxless solder), and IVB instead of the Tim cream (similar to grease), the thermal conductivity of the two distinctly different, the former can reach 80 W / MK, and Tim cream only 5 W / MK, many foreign media processor on IVB were open cover test, replaced by higher heat transfer coefficient of liquid metal cooling ointment after the temperature dropped 15-20 DEG C. So more advanced technology will make the power density increased this may not be established.
Semiconductor technology is the key to determine the performance of a variety of integrated circuits, power, this class we briefly introduce the advanced technology brings two advantages -- transistor density enhance and reduce the cost, secondly is transistor frequency increase and improve performance while reducing power consumption. However, the development of semiconductor technology is now close to 10nm, and then go down the process of upgrading the difficulty is growing, technology companies urgently need to find new materials, technology to break the barriers. At this point, Intel has expressed their confidence, said 7Nm nodes on the company will return to Moore's law on track, to maintain the pace of 2 years to upgrade a process.