Capacitor Isolation Dielectric Layering for High Breakdown Voltage
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Solution Overview
Problem
Existing capacitors in semiconductor integrated circuits face challenges in achieving high breakdown voltage and isolation quality, particularly in 3D devices, where the scaling down process increases complexity and requires advanced manufacturing techniques.
Innovation Solution
The development of a capacitor structure with an ultra-thick insulator layer and a specific method for forming the isolation dielectric layer using plasma-enhanced chemical vapor deposition, which includes depositing multiple sub-layers under controlled conditions to achieve high breakdown voltage and reduce stress, thereby improving the quality of the isolation layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single thick insulator layer is deposited to achieve high breakdown voltage, then the breakdown voltage increases, but stress and peeling issues worsen due to uniform stress distribution
Solution Approach 1:
The thick insulator layer (e.g., 10 micrometers) is divided into multiple sub-layers (e.g., five 2-micrometer sub-layers) deposited sequentially. Each sub-layer is formed independently with controlled deposition parameters, allowing stress management while achieving the required total thickness for high breakdown voltage. The segmentation principle resolves the contradiction by distributing stress across multiple interfaces rather than creating uniform stress in a single thick layer.
Solution Approach 2:
The deposition process uses periodic action by alternating between depositing insulator material and performing in-situ plasma treatments or annealing steps between each sub-layer deposition. This periodic process allows stress relaxation and improves adhesion at each interface, preventing peeling while building up the required thickness for high breakdown voltage capability.
2Manufacturing precision
If multiple sub-layers are deposited to reduce stress and improve isolation quality, then the isolation quality improves, but the manufacturing complexity increases
Solution Approach 1:
Multiple deposition steps for creating sub-layers are merged into a single continuous process chamber without breaking vacuum. The insulator deposition and plasma treatment steps are combined in-situ, eliminating the need for separate processing chambers and reducing manufacturing complexity while maintaining the benefits of multiple sub-layers for improved isolation quality.
Solution Approach 2:
A plasma treatment step acts as an intermediary between sub-layer depositions, serving as a mediator that improves adhesion and reduces stress without requiring additional complex processing equipment. The plasma process is integrated into the existing deposition chamber, using the same vacuum environment to perform both deposition and plasma treatment functions.
3Reliability
If the insulator layer thickness is increased to support high voltage operations, then the breakdown voltage increases, but the risk of stress-induced peeling increases
Solution Approach 1:
Each sub-layer is deposited with controlled thickness and followed by in-situ plasma treatment or annealing that acts as a cushioning step, pre-conditioning the layer to reduce stress accumulation before the next sub-layer is added. This beforehand cushioning prevents stress-induced peeling while allowing the total thickness to be increased for high breakdown voltage support.
Solution Approach 2:
The insulator structure uses composite material approach by creating a multi-layered system where each sub-layer may have slightly different composition or deposition conditions, creating a composite structure that distributes stress more effectively than a homogeneous single layer, thereby preventing peeling while achieving the required breakdown voltage.
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 approach enhances the breakdown voltage of capacitors by about 5% and improves the quality of the isolation dielectric layer, reducing stress and peeling issues, thus supporting high voltage operations in semiconductor devices.
Implementation Method 1
depositing the isolation dielectric layer of the capacitor over the bottom electrode. Depositing the isolation dielectric layer includes heating the substrate to a predetermined temperature range; depositing a first sub-layer of the isolation dielectric layer at the predetermined temperature range; cooling down the substrate and the first sub-layer; heating the substrate and the first sub-layer to the predetermined temperature range; and depositing a second sub-layer of the isolation dielectric layer on the first sub-layer at the predetermined temperature range
Data Source
AI summary
A method includes forming a bottom electrode of a capacitor over a substrate; depositing an isolation dielectric layer of the capacitor over the bottom electrode; and forming a top electrode of the capacitor over the isolation dielectric layer. Depositing the isolation dielectric layer includes heating the substrate to a predetermined temperature range; depositing a first sub-layer of the isolation dielectric layer at the predetermined temperature range; cooling down the substrate and the first sub-layer; heating the substrate and the first sub-layer to the predetermined temperature range; and depositing a second sub-layer of the isolation dielectric layer on the first sub-layer at the predetermined temperature range. Cooling down the substrate and the first sub-layer and heating the substrate and the first sub-layer are performed under an vacuum condition without vacuum break therebetween.