Void-Free Shallow Trench Isolation via ALD Oxide and Nitride Segmentation
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Solution Overview
Problem
As semiconductor device integration increases, it becomes challenging to form a void-free field insulating material in shallow trench isolation (STI) regions.
Innovation Solution
A method involving the formation of a field trench in a silicon substrate, followed by sequential deposition and partial removal of oxide and nitride layers using atomic layer deposition (ALD) and wet etching processes, ensuring conformal profiles and void-free insulating material formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional filling methods are used for STI regions, then the trench can be filled, but voids form in the field insulating material due to increased device integration and smaller trench dimensions
Solution Approach 1:
The field insulating material is deposited in multiple sequential layers (first oxide layer, first nitride layer, second oxide layer) rather than as a single continuous fill. This segmentation allows each layer to be formed with precise thickness control and proper interfaces, eliminating voids that would occur in a single-step fill process for high-density STI regions.
Solution Approach 2:
The first oxide layer is formed with a preliminary thickness greater than the final required thickness, then partially removed to create the first thinned oxide layer. This preliminary over-deposition ensures complete trench coverage before refinement, preventing voids during the thinning process and achieving the desired final thickness with proper void-free interfaces.
2Manufacturing precision
If multiple deposition and removal steps are performed to achieve void-free material, then manufacturing precision improves, but process complexity increases
Solution Approach 1:
The patent uses homogeneous material compositions for each layer (oxide layers and nitride layers) with consistent properties throughout. This homogeneity ensures uniform deposition characteristics and predictable etching behavior across all steps, maintaining high interfacial quality and bonding characteristics while managing process complexity through material consistency rather than varying process parameters.
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 method achieves a void-free field insulating material with improved interfacial properties and bonding characteristics, enhancing the semiconductor device's electrical and thermal performance.
Implementation Method 1
The forming the first oxide layer may include depositing silicon oxide using an atomic layer deposition (ALD) method. The forming the first nitride layer may include depositing silicon nitride using an atomic layer deposition (ALD) method.
Implementation Method 2
The partially removing the surface of the first oxide layer includes processing the surface of the first oxide layer using a wet etching solution including HF.
Implementation Method 3
The partially removing the surface of the first nitride layer includes processing the surface of the first nitride layer using a wet etching solution including H3PO4.
Implementation Method 4
The method may further include performing an oxidation process for supplying an oxygen ion or an oxygen radical in the silicon substrate through the first oxide layer, after the forming the first oxide layer.
Data Source
AI summary
Methods of fabricating a semiconductor device include forming a field trench in a silicon substrate, forming a first oxide layer in the field trench, forming a first thinned oxide layer by partially removing a surface of the first oxide layer, and forming a first nitride layer on the first thinned oxide layer.