Semiconductor Contact Hole Cleaning via Plasma and HF Vapor
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Solution Overview
Problem
Conventional semiconductor device manufacturing methods fail to completely remove damage layers and native oxide films from contact holes, leading to increased contact resistance and transistor performance deterioration, especially when dealing with stacked insulating films.
Innovation Solution
A semiconductor device manufacturing method involving dry-etching, plasma-assisted dry cleaning with oxidized gases, followed by wet processing and chemical dry etching using NF3 or HF, and heat treatment to remove damage layers and native oxide films, ensuring a clean conducting layer surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wet cleaning is used to remove damage layers, then the cleaning process is simple, but the damage layer and native oxide film cannot be completely removed, leading to increased contact resistance
Solution Approach 1:
The cleaning process is divided into multiple sequential steps: dry cleaning to remove organic contaminants, wet cleaning to remove inorganic contaminants, and HF vapor treatment to remove native oxide films. Each step targets specific types of contamination, achieving complete removal that single-method cleaning cannot accomplish.
Solution Approach 2:
The invention changes the cleaning parameters by introducing plasma treatment with specific gases (O2, NF3, CF4) at controlled temperatures and powers, followed by wet cleaning with specific chemical solutions, and finally HF vapor treatment. These parameter changes enable complete removal of all contamination types while protecting the conducting layer.
2Manufacturing precision
If multiple cleaning steps are added to completely remove damage layers and oxide films, then cleaning completeness improves, but the manufacturing process complexity increases
Solution Approach 1:
Dry cleaning and plasma treatment are performed as preliminary actions before wet cleaning and barrier metal deposition. This preliminary removal of organic contaminants and damage layers prepares the surface for subsequent steps, ensuring that each subsequent process works on a pre-conditioned surface, which improves overall effectiveness.
Solution Approach 2:
The invention introduces intermediate treatment steps (plasma treatment with O2, NF3, or CF4, followed by specific wet cleaning solutions) that act as mediators between the damage layer removal and the final oxide film removal. These intermediaries prepare the surface progressively, enabling complete cleaning while maintaining process control.
3Manufacturing precision
If RIE etching is used to make contact holes, then the etching precision is good, but damage layers are formed on the sidewall and bottom of the contact hole
Solution Approach 1:
The damage layer formed by RIE etching is converted into a target for selective removal. The multi-step cleaning process specifically targets and removes these damage layers through plasma treatment and chemical cleaning, transforming the harmful byproduct of precise etching into a controlled removal target that improves final contact quality.
Solution Approach 2:
Plasma treatment with oxidizing gases (O2, NF3) is used to oxidize and remove the damage layer formed during RIE etching. The strong oxidizing environment converts the damaged silicon material into removable compounds that can be easily eliminated in subsequent cleaning steps, preventing contact resistance issues.
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 method effectively reduces contact resistance and improves transistor performance by thoroughly removing damage layers and native oxide films, maintaining the integrity of the semiconductor device.
Implementation Method 1
supplying plasma excited from an oxidized gas onto the exposed conducting layer to dry-clean a damage layer produced in the connection hole
Implementation Method 2
etching an oxide film formed in the connection hole as a result of the wet process by a chemical dry process using a gas including either NF3 or HF
Implementation Method 3
removing a thermally decomposable reaction product as a result of the etching by heat treatment
Data Source
AI summary
An insulating film formed on a conducting layer is dry-etched so as to make a connection hole in the insulating film to expose the conducting layer. Plasma is supplied onto the exposed conducting layer to dry-clean a damage layer produced in the connection hole. A product produced in the connection hole as a result of the dry cleaning is removed by a wet process. An oxide film formed in the connection hole as a result of the wet process is etched by a chemical dry process using a gas including either NF3 or HF. A thermally decomposable reaction product produced as a result of the etching is removed by heat treatment.