This variation
accounts for deviations in the semiconductor fabrication process. Usually
process variation is treated as a percentage variation in the performance
calculation. Variations in the process parameters can be impurity concentration
densities, oxide thicknesses and diffusion depths. These are caused bye non
uniform conditions during depositions and/or during diffusions of the
impurities. This introduces variations in the sheet resistance and transistor
parameters such as threshold voltage. Variations are in the dimensions of the
devices, mainly resulting from the limited resolution of the photolithographic
process. This causes (W/L) variations in MOS transistors.
Process variations are due to variations in the manufacture conditions such as temperature, pressure and dopant concentrations. The ICs are produced in lots of 50 to 200 wafers with approximately 100 dice per wafer. The electrical properties in different lots can be very different. There are also slighter differences in each lot, even in a single manufactured chip. There are variations in the process parameter throughout a whole chip. As a consequence, the transistors have different transistor lengths throughout the chip. This makes the propagation delay to be different everywhere in a chip, because a smaller transistor is faster and therefore the propagation delay is smaller.
Process variations are due to variations in the manufacture conditions such as temperature, pressure and dopant concentrations. The ICs are produced in lots of 50 to 200 wafers with approximately 100 dice per wafer. The electrical properties in different lots can be very different. There are also slighter differences in each lot, even in a single manufactured chip. There are variations in the process parameter throughout a whole chip. As a consequence, the transistors have different transistor lengths throughout the chip. This makes the propagation delay to be different everywhere in a chip, because a smaller transistor is faster and therefore the propagation delay is smaller.
We know that low threshold std cell have high leakage and vice versa.....I want to know the reason???? What is the physics in it???????
ReplyDeleteBecause the subthreshold leakage increase exponentially with the reduction of Vt.
DeleteSo we can see that Lvt have more power consumption than Svt.
Because the subthreshold leakage increase exponentially with the reduction of Vt.
DeleteSo we can see that Lvt have more power consumption than Svt.
Because the subthreshold leakage increase exponentially with the reduction of Vt.
DeleteSo we can see that Lvt have more power consumption than Svt.
As we know that Lvt have high leakage and vice versa......I want to know the reason.....What is the Physics behind it?
ReplyDelete