Thin Film Transfer Stack With Etch Stop and Diffusion Barrier
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Solution Overview
Problem
As semiconductor devices continue to shrink in size, challenges arise in transferring thin semiconductor layers with high etching selectivity and preventing dopant out-diffusion, which affects the quality and efficiency of manufacturing processes.
Innovation Solution
A multi-layered substrate structure is used, comprising a sacrificial substrate, an etch stop layer made of highly doped semiconductor material, and a diffusion barrier layer with alternating silicon and oxygen-inserted partial monolayers, allowing for the transfer of a thin, high-quality semiconductor layer with reduced dopant diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a thin semiconductor layer is transferred using conventional substrate structures, then the transfer process becomes difficult to control, but adding complex multi-layer structures increases manufacturing complexity
Solution Approach 1:
The substrate is segmented into multiple functional layers: a sacrificial substrate layer, an etch stop layer, and a diffusion barrier layer. Each layer serves a specific function in the transfer process, enabling precise control over the thin semiconductor layer transfer while keeping the overall structure manageable through clear functional division.
Solution Approach 2:
The etch stop layer acts as an intermediary between the sacrificial substrate and the thin semiconductor layer. This intermediate layer enables selective removal of the sacrificial substrate while protecting the thin semiconductor layer, facilitating controlled transfer without direct contact between the sacrificial substrate removal process and the delicate semiconductor layer.
2Manufacturing precision
If highly doped semiconductor material is used for the etch stop layer to improve etching selectivity, then dopant out-diffusion increases, but reducing doping concentration reduces etching selectivity
Solution Approach 1:
The diffusion barrier layer serves as an intermediary between the highly doped etch stop layer and the thin semiconductor layer. It blocks the out-diffusion of dopants from the etch stop layer into the thin semiconductor layer, allowing the etch stop layer to maintain high doping concentration for etching selectivity without compromising the purity of the thin semiconductor layer.
Solution Approach 2:
The substrate structure is segmented to separate the etching function (handled by the highly doped etch stop layer) from the protection function (handled by the diffusion barrier layer). This segmentation allows each layer to be optimized for its specific function without compromising the other.
3Productivity
If the thin semiconductor layer is made thinner to improve device integration density, then handling and transfer become more difficult, but making it thicker reduces integration density
Solution Approach 1:
The etch stop layer and diffusion barrier layer together form an intermediary support structure that enables handling and transfer of ultra-thin semiconductor layers. This intermediary structure provides mechanical support during processing while allowing the thin semiconductor layer to achieve the thickness required for high integration density.
Solution Approach 2:
The invention enables the thin semiconductor layer to be processed at thicknesses that would be too thin for conventional handling, by changing the parameter of layer thickness to values optimized for integration density while using the multi-layer substrate structure to maintain manufacturability.
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 structure enables efficient transfer of a thin semiconductor layer with high etching selectivity and uniformity, reducing manufacturing time and cost while maintaining device performance.
Implementation Method 1
a diffusion barrier layer over the etch stop layer and beneath the semiconductor layer. The diffusion barrier layer comprises alternating layers of silicon and oxygen-inserted partial monolayers, and reduces out-diffusion of the dopant of the etch stop layer into the semiconductor layer of the substrate
Implementation Method 2
The etch stop layer is formed of a highly doped semiconductor material to provide excellent etching selectivity over the diffusion barrier layer
Data Source
AI summary
A method of forming a semiconductor device includes: forming an etch stop layer over a substrate; forming a first diffusion barrier layer over the etch stop layer; forming a semiconductor device layer over the first diffusion barrier layer, the semiconductor device layer including a transistor; forming a first interconnect structure over the semiconductor device layer at a front side of the semiconductor device layer, the first interconnect structure electrically coupled to the transistor; attaching the first interconnect structure to a carrier; removing the substrate, the etch stop layer, and the first diffusion barrier layer after the attaching; and forming a second interconnect structure at a backside of the semiconductor device layer after the removing.