Browse Prior Art Database

Method of Heat Sink Structure for SOI Circuit Application

IP.com Disclosure Number: IPCOM000011629D
Original Publication Date: 2003-Mar-10
Included in the Prior Art Database: 2003-Mar-10
Document File: 3 page(s) / 33K

Publishing Venue

Motorola

Related People

Yanyao Yu: AUTHOR [+3]

Abstract

This disclosure describes heat sink structures for semiconductor devices, especially for SOI circuits. SOI (=Silicon On Insulator) technology has received much attention because of its high performance capability over conventional bulk technology. However, SOI transistors are built on a layer of thermally insulating silicon dioxide, which can lead to higher operating temperatures than in equivalent bulk process devices. It is required to implement heat sink structure in order to reduce a temperature increase due to thermal insulation during SOI circuit application.

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Method of Heat Sink Structure for SOI Circuit Application

Authors : Yanyao Yu, Michael A. Mendicino, and Byoung W. Min

Abstract :

        � � � � � � � � � � � This disclosure describes heat sink structures for semiconductor devices, especially for SOI circuits.

        � � � � � � � � � � � SOI (=Silicon On Insulator) technology has received much attention because of its high performance capability over conventional bulk technology. However, SOI transistors are built on a layer of thermally insulating silicon dioxide, which can lead to higher operating temperatures than in equivalent bulk process devices. It is required to implement heat sink structure in order to reduce a temperature increase due to thermal insulation during SOI circuit application.

A thermal conductivity determines how effectively heat can be conducted. (See table below for thermal conductivity of various materials.) The insulating layer, usually oxide (SOI Box in the below table), has 100X high thermal conductivity over conventional p-type silicon.

First, the low thermal conductivity of the Box impedes the vertical flux of heat from the device to the underlying substrate, causing a higher operating temperature in the device. Second, the buried oxide and trench field oxide interferes with the horizontal spreading of heat away from the device, limiting the effective cooling area. This effect will be somewhat mitigated by metal interconnect to device, which provides a thermal path for horizontal spreading of heat

. By the way, it is well known that circuit performance will be degraded as operating temperature increases. Thus, the increased temperature due to poor thermal conduction of SOI circuit weakens its high performance advantage over bulk circuit.

        � � � � � � � � � � � The thermal insulation issues described above are known. A multi-finger metal structure has been used as a heat sinker. However the top area, o...