Selective Epitaxial Growth Contact Plug Formation
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Solution Overview
Problem
Conventional SAC techniques face challenges in miniaturization and preventing short circuits between contact plugs and gate electrodes due to high aspect ratios of contact holes, which limits the reduction of the bottom diameter and increases the risk of etching errors.
Innovation Solution
The method involves forming a semiconductor device with a first and second epitaxial silicon layer on an impurity diffusion region using selective epitaxial growth, followed by the deposition of an interlayer insulating film and the formation of contact holes that are filled with a conductive material, reducing the aspect ratio and preventing short circuits through the use of silicon nitride sidewalls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional SAC technique is used to form contact holes, then alignment margin between gate electrode and contact hole is eliminated, but aspect ratio of contact holes becomes high which limits miniaturization
Solution Approach 1:
The contact hole formation process is segmented into multiple etching steps with different selectivity ratios. First, oxide film is etched with a first etching solution, then silicon nitride film is etched with a second etching solution. This segmentation allows control over the etching depth and aspect ratio at each stage, preventing excessive depth accumulation that would limit miniaturization.
Solution Approach 2:
The invention changes the etching parameters by using etching solutions with different selectivity ratios for oxide film and silicon nitride film. By adjusting the selectivity ratio and controlling the etching amount in each step, the aspect ratio is optimized to enable further miniaturization while maintaining manufacturing precision.
2Length of moving object
If etching amount is increased to form contact holes, then contact hole depth increases, but bottom diameter decreases causing short circuit between contact plug and gate electrode
Solution Approach 1:
The etching process is divided into multiple steps where oxide film etching and silicon nitride film etching are performed separately with different selectivity ratios. This segmentation allows the bottom diameter to be controlled more precisely by managing the etching amount in each step, preventing excessive reduction that would cause short circuits.
Solution Approach 2:
Silicon nitride film acts as an intermediary layer with high etching selectivity. By controlling the etching of this intermediary layer with a second etching solution, the contact hole depth is regulated without excessively reducing the bottom diameter, thereby preventing short circuits between contact plug and gate electrode.
3Manufacturing precision
If high etching selectivity of silicon nitride film is used, then contact holes can be formed in self-aligned manner, but etching time increases reducing productivity
Solution Approach 1:
The etching process is segmented into two distinct steps: first etching oxide film with a first etching solution, then etching silicon nitride film with a second etching solution. This segmentation allows optimization of etching speed in each step while maintaining self-alignment precision, improving overall productivity compared to using a single slow etching process.
Solution Approach 2:
The invention changes the etching parameters by selecting etching solutions with different selectivity ratios for different layers. This allows faster etching of oxide film in the first step, improving productivity, while still achieving precise self-alignment through controlled etching of silicon nitride film in the second step.
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 enables the miniaturization of semiconductor devices by reducing the etching amount, increasing the margin against short circuits, and extending the lifespan of the silicon nitride film, thus enhancing the reliability and efficiency of contact plug formation.
Implementation Method 1
forming a first layer on the impurity diffusion region by a selective epitaxial growth method; forming a second layer on the first layer by the selective epitaxial growth method
Data Source
AI summary
A method for manufacturing a semiconductor device comprises forming a first layer on an impurity diffusion region in a semiconductor substrate by a selective epitaxial growth method, forming a second layer on the first layer by the selective epitaxial growth method, forming a contact hole penetrating an interlayer insulating film in a thickness direction thereof and reaching the second layer, and filling a conductive material into the contact hole to form a contact plug including the first and second layers and the conductive material.