Why do you want to make the wafer bigger? The bigger the better, why?
Because each layer is insulated by silicon dioxide, it is equivalent to a capacitor structure. The larger the span, the greater the capacity of the wiring. The higher the frequency, the more serious side effects such as the integral effect of the long distance transmission. Basically thought GHz must use the following line width.18 technology. Chip size also affects power consumption. With the same mask and the same operating frequency, the smaller the line width, the smaller the voltage. The power consumption is proportional to the square of the voltage. Want to pursue low power you have to honestly narrow the line width. The semiconductor industry in the world are going to kill red eye, if we do not have shortcut yiwofeng to dive in.
The cost of the chip is directly related to the area. On the same chip, the more chips can be carved, the lower the price of the chip. Because silicon chips are inevitably produced defects (such as impurities, etc.). The larger the area of a chip, the higher the probability of the collision, and the higher the proportion of the whole wafer. A chip to do one hundred chips, a defect is 1\%. If only do ten, out of a defect is 10\%. An extreme example is the large CCD, professional camera or digital camera with the CCD is 23.7x15.6mm, light by the light area of 370 square millimeters, quickly catch up with the area of the high-end RISC processor
So the price of a light on the CCD. Because the yield is very low. Astronomical telescopes or military reconnaissance equipment used on the larger size of CCD (such as 4, 8 inches or even 12 inches CCD) is simply astronomical. Looking for a piece of silicon wafer that is close to zero defect is probably a vast project. And the speed of the chip is also affected by the area. The larger the area, the greater the span of the wiring, the greater the frequency of interference and signal
