Nitride Barrier Blocks Ion Diffusion in Diamond SOI
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Solution Overview
Problem
High-purity diamond SOI technologies face issues with elevated levels of mobile heavy metal ions diffusing from the diamond and seed layers into the adjacent silicon layer, degrading the quality of silicon and reducing carrier lifetime, and contaminating fabrication equipment.
Innovation Solution
A thin nitride barrier is placed between the diamond SOI layer and the device silicon layer to block ion diffusion, with additional nitride layers and oxide growth strategies to maintain device integrity and carrier lifetime, while minimizing thermal conductivity impact and simplifying trench isolation processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thin nitride barrier is placed between the diamond SOI layer and the device silicon layer, then ion diffusion is blocked and carrier lifetime is improved, but the thermal conductivity of the structure is reduced
Solution Approach 1:
The nitride barrier layer is applied locally only at the interface between the diamond SOI layer and the device silicon layer, where ion diffusion occurs. This localized application provides the necessary ion blocking function while minimizing the overall impact on thermal conductivity, as the barrier occupies only a small portion of the thermal conduction path.
Solution Approach 2:
The structure employs a composite material approach by combining diamond SOI layer, nitride barrier layer, and device silicon layer into a multi-layer composite structure. Each layer contributes its specific properties: diamond provides high thermal conductivity and mechanical strength, nitride provides ion diffusion barrier, and silicon provides device functionality. The composite structure achieves both ion blocking and thermal management requirements.
2Reliability
If additional nitride layers and oxide growth are performed on the device wafer, then device integrity is maintained and contamination is reduced, but the processing complexity increases
Solution Approach 1:
The nitride barrier layer and oxide layers are formed on the device wafer before bonding to the handle wafer. This preliminary action protects the device wafer surfaces and interfaces from contamination and damage during subsequent processing steps, ensuring device integrity while establishing a controlled environment for subsequent operations.
Solution Approach 2:
The protective barrier structure is segmented into multiple distinct layers (nitride barrier, oxide layers) with specific functions. The nitride layer provides ion diffusion blocking, while the oxide layers provide surface protection and interface quality control. This segmentation allows each layer to be optimized for its specific function while collectively maintaining device integrity.
3Reliability
If diamond and nitride layers are formed on a handle wafer rather than a device wafer, then the device wafer integrity is maintained, but the manufacturing process becomes more complex
Solution Approach 1:
The device structure is segmented into two separate wafers: the device wafer containing the active device structures, and the handle wafer containing the diamond and nitride layers. This segmentation allows the device wafer to be processed and tested independently to ensure integrity, while the handle wafer provides mechanical support and thermal management. The separate processing of each wafer simplifies quality control and defect isolation.
Solution Approach 2:
The handle wafer acts as an intermediary substrate that provides mechanical support, thermal management, and interface quality control. By forming the diamond and nitride layers on the handle wafer rather than the device wafer, the device wafer is protected from contamination and damage during processing, while the handle wafer absorbs the mechanical and thermal stresses.
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
The nitride barrier effectively blocks ion diffusion, improves carrier lifetime, and simplifies subsequent processing steps without significantly affecting thermal conductivity, maintaining the integrity of the device silicon and reducing contamination risks.
Implementation Method 1
A thin nitride barrier is placed between the diamond SOI layer and the device silicon layer to block ion diffusion
Implementation Method 2
Thermal conductivity of diamond is ten times better than silicon and one thousand times better than oxide
Data Source
AI summary
A method and structure for a semiconductor device, the device including a handle wafer, a diamond layer formed directly on a front side of the handle wafer, and a thick oxide layer formed directly on a back side of the handle wafer, the oxide layer of a thickness to counteract tensile stresses of the diamond layer. Nitride layers are formed on outer surfaces of the diamond layer and thick oxide layer and a polysilicon is formed on outer surfaces of the nitride layers. A device wafer is bonded to the handle wafer to form the semiconductor device.