Semiconductor Device SiN ALD Oxide Moisture Barrier
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Solution Overview
Problem
Conventional semiconductor devices in non-hermetic packages face moisture intrusion issues due to inadequate coverage of SiO or SiN films over T-shaped gate electrodes, leading to semiconductor degradation, and increasing film thickness worsens high-frequency characteristics.
Innovation Solution
A semiconductor device with a SiN film formed by PECVD directly contacting the semiconductor substrate, followed by an atomic layer deposition oxide film providing excellent coverage, reducing moisture intrusion without increasing film thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of SiN film is increased to improve moisture resistance, then moisture resistance is improved, but capacitance increases and high-frequency characteristics deteriorate
Solution Approach 1:
The protective film is segmented into two distinct layers: a SiN film layer and an oxide film layer. The SiN film layer (thickness: 5-20 nm) provides good interface formation with the semiconductor substrate, while the oxide film layer (thickness: 2-10 nm) deposited by ALD provides dense coverage and moisture resistance. This segmentation allows each layer to optimize its function without requiring excessive total thickness, thereby maintaining high-frequency characteristics while improving moisture resistance.
Solution Approach 2:
The invention uses a composite film structure combining SiN and oxide materials. The SiN material provides excellent interface properties with the semiconductor substrate, while the oxide material (such as Al2O3, HfO2, or TiO2) provides superior density and moisture barrier properties. This composite structure achieves synergistic effects where the combination of materials provides better overall moisture resistance than either material alone, without increasing total film thickness to levels that would degrade high-frequency performance.
2Ease of manufacture
If PECVD process is used to form SiO or SiN film, then manufacturing cost is reduced, but coverage over level differences and overhangs is insufficient
Solution Approach 1:
The protective film formation process is segmented into two steps using two different deposition methods. First, PECVD is used to form the SiN film layer which provides good interface formation and is cost-effective. Second, ALD is used to form the oxide film layer which provides excellent step coverage and conformal deposition over level differences and overhangs. This segmentation of processes allows each method to play to its strengths, achieving both cost efficiency and manufacturing precision.
Solution Approach 2:
The SiN film formed by PECVD acts as an intermediary layer between the semiconductor substrate and the final oxide protective layer. This intermediary layer provides a good interface with the substrate while allowing the subsequent ALD oxide layer to conformally cover complex topographies including level differences and overhangs. The combination of these two layers mediates between the cost-effectiveness of PECVD and the superior coverage of ALD.
3Manufacturing precision
If ALD process is used to form protective film, then coverage and denseness are improved, but moisture resistance cannot be improved due to moisture intrusion at semiconductor-film interface
Solution Approach 1:
Instead of using ALD to form the entire protective film (which would provide good coverage but poor interface formation), the invention inverts the approach: PECVD is used first to form the SiN film that directly contacts the semiconductor substrate, providing excellent interface formation. Then ALD is used to form the oxide layer on top, providing dense coverage and moisture barrier properties. This inversion of the conventional approach allows each process to optimize its primary function.
Solution Approach 2:
The protective structure uses a composite of SiN and oxide materials where the SiN layer provides superior interface properties with the semiconductor substrate, preventing moisture intrusion at the critical semiconductor-film interface. The oxide layer provides dense, conformal coverage that blocks moisture pathways. This composite material structure addresses both the coverage requirement and the moisture resistance requirement that cannot be satisfied by a single material.
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 solution effectively enhances moisture resistance and maintains high-frequency performance by forming a robust interface between the SiN film and semiconductor substrate, preventing moisture-induced deterioration.
Implementation Method 1
a SiN film formed by plasma-enhanced chemical vapor deposition (PECVD)
Implementation Method 2
an atomic layer deposition film, which has good coverage
Data Source
AI summary
A semiconductor device includes: a semiconductor substrate; a gate electrode on the semiconductor substrate; a SiN film on the semiconductor substrate and the gate electrode; and an oxide film on the SiN film, wherein the oxide film is an atomic layer deposition film including atomic layers alternately deposited.