Diffusion Barrier Coated Metal Substrates for Semiconductor Devices
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Solution Overview
Problem
Metal foil substrates in semiconductor devices undergo diffusion of atoms like iron and chromium at elevated temperatures, compromising the electrical properties of semiconductor layers due to high diffusivity, leading to issues such as threshold voltage shifts and increased leakage current.
Innovation Solution
A diffusion barrier layer, comprising materials like titanium nitride or aluminum nitride, is deposited on the metal substrate to prevent the diffusion of metal atoms into semiconductor layers, with additional insulator layers electrically isolating the diffusion barrier from the semiconductor devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If metal foil substrates are used for semiconductor devices, then flexibility and high-temperature processing capability are improved, but metal atom diffusion into semiconductor layers occurs at elevated temperatures, degrading electrical properties
Solution Approach 1:
A diffusion barrier layer is introduced as an intermediary between the metal foil substrate and the semiconductor layer. This barrier layer (comprising materials such as titanium nitride, aluminum nitride, or their nanolaminates) selectively blocks metal atom diffusion while allowing thermal energy to pass through, thereby protecting the semiconductor layer from contamination during high-temperature processing without compromising the flexibility and thermal processing capabilities of the metal substrate
Solution Approach 2:
The diffusion barrier layer employs composite material structures, specifically nanolaminates of alternating titanium nitride and aluminum nitride layers. This composite structure leverages the complementary properties of each material: titanium nitride provides excellent diffusion barrier properties, while aluminum nitride offers high thermal stability and flexibility compatibility. The nanolaminate architecture creates multiple interfaces that collectively block metal atom diffusion pathways more effectively than single-layer barriers
2Reliability
If diffusion barrier layers are deposited on metal substrates, then metal atom diffusion is prevented, but additional insulator layers are required to electrically isolate the barrier from semiconductor devices, increasing device complexity
Solution Approach 1:
The diffusion barrier layer structure is designed to serve multiple functions simultaneously: it acts as a diffusion barrier to block metal atom migration, provides electrical isolation between the conductive metal substrate and the semiconductor layer, and serves as a structural foundation for subsequent semiconductor layer deposition. This multi-functionality reduces the need for separate dedicated layers for each function, thereby limiting the increase in device complexity
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 diffusion barrier effectively reduces metal atom diffusivity by several orders of magnitude, maintaining the electrical properties of semiconductor devices and preventing undesirable changes in device characteristics during high-temperature processing.
Implementation Method 1
a diffusion barrier layer, comprising materials like titanium nitride or aluminum nitride, is deposited on the metal substrate to prevent the diffusion of metal atoms into semiconductor layers
Implementation Method 2
with additional insulator layers electrically isolating the diffusion barrier from the semiconductor devices
Data Source
Figure 1~2C
Figure 2D~3C
Figure 4A~5
AI summary
Semiconductor devices on a diffusion barrier coated metal substrates, and methods of making the same are disclosed. The semiconductor devices include a metal substrate, a diffusion barrier layer on the metal substrate, an insulator layer on the diffusion barrier layer, and a semiconductor layer on the insulator layer. The method includes forming a diffusion barrier layer on the metal substrate, forming an insulator layer on the diffusion barrier layer; and forming a semiconductor layer on the insulator layer. Such diffusion barrier coated substrates prevent diffusion of metal atoms from the metal substrate into a semiconductor device formed thereon.