Thin Film Transfer with Diffusion Barrier for Dopant Control
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Solution Overview
Problem
The semiconductor industry faces challenges in reducing minimum feature sizes, leading to issues such as out-diffusion of dopants from etch stop layers, which affects the quality and thickness of semiconductor layers, making it difficult to achieve high-performance devices and efficient manufacturing processes.
Innovation Solution
A multi-layered substrate structure is introduced, comprising a sacrificial substrate, an etch stop layer with high dopant concentration, and a diffusion barrier layer with alternating silicon and oxygen-inserted partial monolayers, which reduces dopant out-diffusion and enables the formation of a thin, high-quality semiconductor layer suitable for transferring to a workpiece through selective etching and bonding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an etch stop layer with high dopant concentration is used to achieve excellent etching selectivity, then etching selectivity is improved, but dopant out-diffusion occurs affecting semiconductor layer quality
Solution Approach 1:
A diffusion barrier layer is introduced as an intermediary between the etch stop layer and the semiconductor layer. This barrier layer prevents dopant diffusion from the etch stop layer into the semiconductor layer, while allowing the etch stop layer to maintain its high dopant concentration for excellent etching selectivity. The intermediary layer thus resolves the conflict between achieving high etching selectivity and preventing dopant contamination.
Solution Approach 2:
The substrate structure is segmented into distinct functional layers: an etch stop layer with high dopant concentration for etching selectivity, a diffusion barrier layer to prevent dopant migration, and a semiconductor layer for device formation. This segmentation allows each layer to optimize its specific function without interfering with other layers, enabling high etching selectivity while preventing dopant out-diffusion.
2Length of moving object
If the semiconductor layer thickness is reduced to achieve thinner devices, then device performance is improved, but total thickness variation increases
Solution Approach 1:
The invention forms a thin semiconductor layer by transferring a copied version of the semiconductor structure from a sacrificial substrate to a workpiece. This transfer process allows precise control of the semiconductor layer thickness while the sacrificial substrate maintains the structural integrity needed for low thickness variation. The copying approach enables thin layer formation without proportionally increasing thickness variation.
3Productivity
If minimum feature sizes are reduced to increase integration density, then integration density is improved, but manufacturing complexity and quality control become more difficult
Solution Approach 1:
The etch stop layer with high dopant concentration is formed in advance on the sacrificial substrate before semiconductor layer formation. This preliminary action creates a well-defined etching boundary that simplifies subsequent processing steps. The pre-formed etch stop layer enables precise control of layer removal and facilitates the manufacturing of smaller features by providing clear etching termination points, thereby reducing overall manufacturing complexity despite reduced feature sizes.
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 solution provides excellent etching selectivity, reduces material costs, and achieves a thinner semiconductor layer with reduced total thickness variation, facilitating the formation of high-performance semiconductor devices and enabling more efficient manufacturing by allowing for easier transfer and integration of semiconductor layers.
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.