Substrate Thinning with Diamond-Like Carbon Stopper Layer
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Solution Overview
Problem
Current methods for thinning semiconductor substrates to create flexible integrated circuit devices face challenges such as limited thinning accuracy, warpage issues, and variations in substrate thickness, which affect element properties and manufacturing yield, especially when aiming for substrates thinner than 50 μm, and are costly due to the expense of silicon substrates.
Innovation Solution
A method involving the formation of a stopper layer with higher hardness than the substrate, typically using diamond-like carbon (DLC), over one surface of the substrate, allowing for thinning or removal through grinding, polishing, or chemical etching, while controlling adhesion to prevent damage to the layer above the stopper and enabling heat treatment without compromising adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If substrate thinning is performed by grinding and polishing to achieve thickness of 50 μm or less, then substrate flexibility is improved, but manufacturing precision deteriorates due to limited accuracy and in-plane uniformity
Solution Approach 1:
The substrate thinning process is divided into multiple stages: initial grinding to reduce thickness, followed by selective removal of the stopper layer, and final polishing. This segmentation allows each stage to optimize for its specific function, achieving both flexibility and precision.
Solution Approach 2:
A stopper layer is formed on the substrate surface before thinning operations begin. This preliminary action protects the underlying circuit elements during grinding and polishing, ensuring manufacturing precision while allowing aggressive thinning to achieve the desired flexibility.
2Adaptability or versatility
If substrate thickness is reduced to improve flexibility, then device adaptability is improved, but manufacturing yield deteriorates due to warpage and stress variations
Solution Approach 1:
The stopper layer provides localized protection and stress management at the substrate surface, allowing different regions of the substrate to be processed with uniform quality. This local intervention prevents warpage and stress variations that would otherwise reduce manufacturing yield.
Solution Approach 2:
The stopper layer acts as an intermediary between the substrate and the thinning process. It mediates the stress and warpage issues that arise during thinning, allowing the substrate to be reduced to flexible thickness while maintaining manufacturing yield.
3Manufacturing precision
If conventional polishing methods are used with abrasive grains softer than the substrate, then substrate surface evenness is improved, but manufacturing precision deteriorates because only chemically bonded portions can be polished selectively
Solution Approach 1:
The invention changes the hardness parameter of the polishing abrasive to be harder than the substrate. This parameter change enables selective polishing of the stopper layer without relying on chemical bonding, improving both surface evenness and manufacturing ease.
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 enables the creation of thinner, more flexible integrated circuit devices with improved manufacturing yield and reduced cost, as it allows for precise thinning and removal of substrates, minimizing variations in element properties and enabling heat treatment without adhesion issues.
Implementation Method 1
A method involving the formation of a stopper layer with higher hardness than the substrate, typically using diamond-like carbon (DLC), over one surface of the substrate
Implementation Method 2
typically using diamond-like carbon (DLC), over one surface of the substrate
Implementation Method 3
allowing for thinning or removal through grinding, polishing, or chemical etching
Data Source
AI summary
It is an object of the present invention to improve a factor which influences productivity such as variation caused by a characteristic defect of a circuit by thinning or production yield when an integrated circuit device in which a substrate is thinned is manufactured. A stopper layer is formed over one surface of a substrate, and an element is formed over the stopper layer, and then, the substrate is thinned from the other surface thereof. A method in which a substrate is ground or polished or a method in which the substrate is etched by chemical reaction is used as a method for thinning or removing the substrate.