Abstract

Some guidelines for the understanding of the technological trends in GaAs IC'S can be found in a brief recall of device and interconnect behaviour under scaling down. Let us recall that the device control parameters are the internal charge Q_t carried by the electrons in the control region end the electron transit time t_t. When N identical devices are driven by N interconnexions, each having the same length and carrying the same charge Q_L, the switching time is aproximately given by t_pd = N t_t (1+Q_L/Q_t). The local speed will then be improved by reducing both t_t and q_l/q_t. as long as Q_L/Q_t is greater than one, a common practice is to increase the control region width (say the gate width). Here Q_t is increased, t_t remaining constant. But it is well known that the counterpart of such an improvement for the current driving capabilities of the device is poundered by an increase in power dissipation. On the other hand, reducing the length of the control region (for instance the gate length of a MESFET) leads to a reduction of t_t and Q_t. So that in order to be effective, one should also scale down the interconnects width of the same quantity.

© 1985 Optical Society of America