PECVD Oxide-Nitride Stacks for 3D Memory
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Solution Overview
Problem
The existing process for depositing layered stacks of materials in semiconductor substrate processing is inefficient as it requires transferring the substrate between multiple PECVD chambers, breaking the vacuum each time, which wastes time and energy.
Innovation Solution
A process is developed to deposit multiple layers of different materials in a single PECVD processing chamber by using alternating current RF power to create an electrical field, generating plasmas for each material layer, and performing plasma and gas purges to ensure clean interfaces and maintain vacuum conditions throughout the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple layers are deposited in different PECVD chambers, then each layer can be deposited with optimized conditions, but the process time and energy consumption increase significantly due to repeated vacuum breaking and substrate transfer
Solution Approach 1:
The patent combines multiple deposition chambers into a single multi-functional PECVD chamber that can deposit different materials (oxide, nitride, silicon) sequentially without breaking vacuum. The chamber is equipped with multiple gas delivery systems and RF power sources that can be switched between different material deposition modes, merging what were previously separate chamber functions into one integrated system.
Solution Approach 2:
The PECVD chamber is designed with universal capabilities to deposit multiple different materials using the same chamber infrastructure. The system includes multiple precursor gas delivery systems (silane for silicon, nitrogen for nitride, oxygen for oxide) and can switch between different deposition chemistries by changing gas flows and RF parameters, making the chamber multi-functional rather than dedicated to a single material.
2Adaptability or versatility
If substrate is transferred between chambers, then different materials can be deposited, but time is lost due to vacuum breaking and re-establishment during each transfer
Solution Approach 1:
The patent maintains continuous vacuum conditions throughout the entire multi-layer deposition process by eliminating chamber transfers. The substrate remains in the same PECVD chamber throughout, and the vacuum is maintained continuously while different precursor gases are introduced and RF power is applied for sequential deposition of oxide, nitride, and silicon layers without interruption.
Solution Approach 2:
The chamber is prepared in advance with multiple gas delivery systems and material sources (silane, nitrogen, oxygen) already in place. The vacuum is established once before the deposition sequence begins, and all subsequent material depositions are performed by switching gas flows and RF parameters rather than by physical chamber changes, eliminating the need for repeated vacuum cycling.
3Productivity
If multiple materials are deposited in sequence, then complex 3D memory structures can be formed, but stress accumulation causes substrate deformation and delamination
Solution Approach 1:
The patent controls deposition parameters (gas flow rates, RF power, pressure, temperature) to precisely control the stress state of each deposited layer. By adjusting these parameters during the deposition of oxide, nitride, and silicon layers, the system can produce layers with balanced or compensating stresses that prevent cumulative stress buildup and substrate deformation while maintaining the complex multi-layer structure.
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 significantly reduces time and energy consumption by maintaining the vacuum and allowing for efficient deposition of multiple layers within a single chamber, while also minimizing substrate deformation by tuning stress levels between layers to prevent delamination.
Implementation Method 1
A first group of process gases flows into the processing chamber and is energized into a first plasma within the PECVD chamber. The plasma has a significant percentage of the atoms or molecules that are ionized and the atoms or molecules release electrons. These energetic electrons can induce dissociation of first process gas molecules and the creation of large quantities of free radicals.
Implementation Method 2
plasma enhanced chemical vapor deposition (PECVD) to deposit a film upon the substrate
Implementation Method 3
Alternating current radio frequency (RF) power can be applied to an electrode which creates an electrical field between a substrate and the electrode
Implementation Method 4
The plasma has a significant percentage of the atoms or molecules that are ionized and the atoms or molecules release electrons
Implementation Method 5
a vacuum is applied to the chamber
Data Source
AI summary
A layer stack of different materials is deposited on a substrate in a single plasma enhanced chemical vapor deposition processing chamber while maintaining a vacuum. A substrate is placed in the processing chamber and a first processing gas is used to form a first layer of a first material on the substrate. A plasma purge and gas purge are performed before a second processing gas is used to form a second layer of a second material on the substrate. The plasma purge and gas purge are repeated and the additional layers of first and second materials are deposited on the layer stack.