Patent ID: 6355537
Filing Date: 2002-03-12
Classification: H01L

Abstract:
A method of providing radio frequency (RF) isolation of device mesas within an integrated circuit (IC), wherein the IC comprises a substrate, an insulating layer formed on the substrate, additional semiconductor layers formed on the insulating layer, a first isolation trench formed in the additional semiconductor layers that extends to the insulating layer and that surrounds a first selected surface area of the additional semiconductor layers, wherein the first selected surface area defines a first device mesa, a second isolation trench formed in the additional semiconductor layers that extends to the insulating layer and that surrounds the first isolation trench and defines a first guard ring region between itself and the first isolation trench, a third isolation trench formed in the additional semiconductor layers that extends to the insulating layer and that surrounds a second selected surface area of the additional semiconductor layers, wherein the second selected surface area defines a second device mesa, and wherein the device mesas each include an integrated circuit device capable of generating RF power, and a fourth isolation trench formed in the additional semiconductor layers that extends to the insulating layer and that surrounds the third isolation trench and defines a second guard ring region between itself and the third isolation trench, the method comprising the steps of:a) isolating the first device mesa from RF power produced by integrated circuit devices external to the first device mesa, wherein the RF power comprises relatively high-frequency small voltage signals, by electrically coupling the first guard ring region to a ground node thereby shunting the RF power to ground and greatly reducing effects of the RF power on the operation of the device in the first device mesa; and b) isolating the second device mesa from RF power produced by integrated circuit devices external to the second device mesa by electrically coupling the second guard ring region to the ground node thereby shunting the RF power to ground and greatly reducing effects of the RF power on the operation of the device in the second device mesa; wherein RF isolation is firther provided between the first and second device mesas by shunting the RF power produced by the devices operating within the device mesas to ground.