Radical Oxide Isolation for Semiconductor Leakage Reduction
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Solution Overview
Problem
Increased leakage current in semiconductor devices leads to higher power consumption and heat generation, affecting performance and reliability, especially in mobile applications, due to factors like off-state leakage, drain-induced barrier lowering, and hot carrier effects.
Innovation Solution
A method involving the formation of a trench on a semiconductor substrate with a radical oxide layer and a nitride layer, where the conduction band offset of the radical oxide layer is greater than that of a thermal oxide layer, to reduce hot electron induced punchthrough and leakage current, using processes like atomic layer deposition and chemical vapor deposition to oxidize a semiconductor layer with free radical atoms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermal oxide layer is used to form the device isolation layer, then the manufacturing process is simple, but the conduction band offset is insufficient leading to hot electron induced punchthrough and increased leakage current
Solution Approach 1:
The patent changes the oxidation method from thermal oxidation to radical-based oxidation (using O2, O3, or H2O2 plasma). This parameter change in the oxidation process creates an oxide layer with superior electrical properties, specifically achieving a conduction band offset greater than 3.5 eV, which effectively suppresses hot electron induced punchthrough and reduces leakage current while maintaining reasonable process complexity
Solution Approach 2:
The patent employs a composite oxidation approach by first forming a thin initial oxide layer (50-200 Å) through thermal or radical oxidation, then forming a second oxide layer (500-2000 Å) through radical oxidation. This composite structure combines the benefits of both oxidation methods to achieve optimal electrical isolation and hot electron suppression
2Productivity
If the channel length of gate is decreased to improve device integration, then the device size is reduced, but hot carrier effects increase leading to higher leakage current
Solution Approach 1:
The patent changes the oxidation parameters to create an oxide layer with enhanced conduction band offset (>3.5 eV) using radical-based oxidation processes. This parameter change in the isolation layer's electrical properties provides stronger potential barriers that suppress hot carrier effects, enabling continued scaling of channel length without excessive leakage current
Solution Approach 2:
The patent introduces a specially formed oxide layer as an intermediary structure between the semiconductor substrate and the device isolation region. This intermediate oxide layer with high conduction band offset acts as a barrier that mediates the interaction between hot carriers and the substrate, preventing hot carrier induced damage and leakage while allowing continued device scaling
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 approach effectively reduces the trapping of hot electrons, thereby minimizing leakage current and enhancing the reliability and performance of semiconductor devices by increasing the conduction band offset and suppressing hot electron induced punchthrough.
Implementation Method 1
the conduction band offset of the radical oxide layer is greater than that of a thermal oxide layer having the same thickness as the radical oxide layer
Implementation Method 2
oxidizing the semiconductor layer using the free radical atoms
Implementation Method 3
decomposition of process gas
Implementation Method 4
decomposition of process gas using plasma generation
Data Source
AI summary
A method of forming a semiconductor device includes forming a trench on a semiconductor substrate to define an active region, forming a radical oxide layer on a sidewall and a bottom surface of the trench, and forming a nitride layer on the radical oxide layer. The conduction band offset of the radical oxide layer is greater than the conduction band offset of a thermal oxide layer having the same thickness as the radical oxide layer.