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Method of Controlling Transient Temperature Differential of Integrated Circuits and Substrates

IP.com Disclosure Number: IPCOM000034258D
Original Publication Date: 1989-Jan-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Dunham, B: AUTHOR [+3]

Abstract

A technique is described whereby the transient temperature difference between integrated circuit chips and their mounting substrates is controlled. Two methods are described aimed at reducing mechanical stress caused by different coefficients of expansion of the materials which make up large-scale integrated (LSI) and very large-scale integrated (VLSI) circuits on semiconductor materials. Especially, the problem caused by "chips" which are essentially the size of a silicon wafer "wafer scale integration" is addressed. Typically, when power is turned on LSI/VLSI circuits, a transient temperature difference occurs between the circuit chips and the substrate, such that mechanical stress will occur. This stress limits the size of chips and/or restricts the placement of contacts on the substrate.

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Method of Controlling Transient Temperature Differential of Integrated Circuits and Substrates

A technique is described whereby the transient temperature difference between integrated circuit chips and their mounting substrates is controlled. Two methods are described aimed at reducing mechanical stress caused by different coefficients of expansion of the materials which make up large-scale integrated (LSI) and very large-scale integrated (VLSI) circuits on semiconductor materials. Especially, the problem caused by "chips" which are essentially the size of a silicon wafer "wafer scale integration" is addressed. Typically, when power is turned on LSI/VLSI circuits, a transient temperature difference occurs between the circuit chips and the substrate, such that mechanical stress will occur. This stress limits the size of chips and/or restricts the placement of contacts on the substrate. When the chip approaches full wafer size, the problem is especially severe. The differential temperature expansion problem exists because power from the circuit chip is the only heat source, for both the chip and the substrate, when the chip is first powered on. Even if the two coefficients of expansion are matched when cool, severe mechanical stress can occur during the warm-up period. The larger the chip, the greater the problem. The concept described herein provides two approaches aimed at maintaining an acceptable minimum temperature difference between chip and substrate during the warm-up period. $ Provide a separate source of temporary heat for the

substrate during the warm-up period.

$ Control the power turn-on rate to the chip. To provide a separate heat source, two approaches are considered. A heating element can be embedded in,...