SRAM Silicon Layer Thinning Reduction via Low-Temp Deposition

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Solution Overview

Problem

Conventional methods of fabricating static random access memory (SRAM) devices often result in a thinning phenomenon of the crystallized silicon layer during annealing, leading to undesirable thickness reduction, which can be removed during subsequent processes.

Innovation Solution

The method involves recessing the interlayer dielectric (ILD) and depositing an amorphous silicon layer at a low temperature, followed by annealing to crystallize it, using the single crystalline silicon layer as a seed, thereby reducing the thinning rate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If an amorphous silicon layer is deposited and annealed at conventional temperatures, then the silicon layer crystallizes, but significant thinning occurs (70% thinning rate)

Engineering Contradiction:

Improvethickness control of crystallized silicon layerVSAvoidloss of silicon layer thickness during annealing

Core Design Contradiction:

Manufacturing precisionVSLoss of substance

Solution Approach 1:

The patent changes the deposition temperature parameter from conventional high temperature to low temperature (below 200°C). This parameter change modifies the microstructure and stress state of the amorphous silicon layer, resulting in significantly reduced thinning (30% thinning rate) during subsequent annealing crystallization processes

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent performs low-temperature deposition as a preliminary action before annealing. This preliminary low-temperature deposition creates an amorphous silicon layer with specific properties that prevent excessive thinning during the subsequent annealing process, thereby preserving layer thickness

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach significantly reduces the thinning rate of the crystallized silicon layer, maintaining its thickness and preventing removal during subsequent processes, as illustrated by a reduction from 70% to 30% thinning rate.

Implementation Method 1

depositing an amorphous silicon layer at a low temperature

Methodology Applied

Scientific EffectDeposition: Deposition (physical)

Implementation Method 2

annealing to crystallize it, using the single crystalline silicon layer as a seed

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Data Source

PatentUS7598141B2Method of fabricating static random access memory

Publication Date: 2009.10.06 SAMSUNG ELECTRONICS CO LTD

AI summary

A method of fabricating a static random access memory device includes selectively removing an insulating film and growing a single crystalline silicon layer using selective epitaxy growth, the single crystalline silicon layer being grown in a portion from which the insulating film is removed; recessing the insulating film; and depositing an amorphous silicon layer on the single crystalline silicon layer and the insulating film, such that the amorphous silicon layer partially surrounds a top surface and side surfaces of the single crystalline silicon layer.