Contact Hole Etching with Oxide-Polymer Buffer for Low Dark Current
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Solution Overview
Problem
During the processing of contact holes in semiconductor devices, silicon nitride films are used as etching stoppers, but over-etching can lead to recess formation in the semiconductor layer, resulting in residual defects that increase dark current.
Innovation Solution
A semiconductor device with a semiconductor layer, a first insulation film, a conductive layer embedded in the insulation film, and an altered layer containing oxygen with hydrogen content equal to or lower than the insulation film, formed through a method involving plasma oxidation, polymer film attraction, and removal using specific gas plasmas to reduce etching-related issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a silicon nitride film is used as an etching stopper during contact hole processing, then etching selectivity is improved, but over-etching causes recess formation in the semiconductor layer and increases dark current
Solution Approach 1:
An altered layer is introduced as an intermediary between the silicon nitride film and the semiconductor layer. This altered layer acts as a buffer that prevents direct contact between the conductive layer and the semiconductor layer, thereby preventing recess formation and residual defects while maintaining etching selectivity.
Solution Approach 2:
The altered layer is formed in advance before the conductive layer is deposited. This preliminary action prepares the interface between the insulation film and semiconductor layer, ensuring that subsequent conductive layer deposition will not cause recess formation or residual defects.
2Productivity
If conventional etching methods are used to form contact holes, then processing efficiency is maintained, but residual defects increase dark current
Solution Approach 1:
The altered layer serves as a mediator that eliminates residual defects at the interface between the insulation film and semiconductor layer, thereby reducing dark current without compromising processing efficiency.
3Device complexity
If the conductive layer is embedded directly into the insulation film opening, then device structure is simplified, but recess formation occurs in the semiconductor layer
Solution Approach 1:
The altered layer is introduced as an intermediary layer between the insulation film and semiconductor layer, preventing direct etching damage to the semiconductor layer while maintaining a relatively simple device structure.
Solution Approach 2:
The altered layer is formed in advance to prevent recess formation before the conductive layer is deposited, ensuring proper interface formation without requiring complex subsequent processing steps.
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 solution effectively reduces recess formation and residual defects, decreasing dark current and improving device performance by minimizing etching damage and increasing pressure resistance.
Implementation Method 1
forming an oxide film by oxidizing, with the use of plasma of a first gas, an upper surface of an insulation film provided on a semiconductor layer containing silicon
Implementation Method 2
attracting a first polymerized film to an upper surface of the oxide film with the use of plasma of a second gas
Implementation Method 3
removing at least a part of the first polymerized film, the oxide film, and the insulation film with the use of plasma of a third gas
Data Source
AI summary
Provided is an etching method capable of reducing a problem caused by etching during processing of contact holes of a semiconductor device. The etching method includes forming an oxide film by oxidizing, with the use of plasma of a first gas, an upper surface of an insulation film provided on a semiconductor layer containing silicon, attracting a first polymerized film to an upper surface of the oxide film with the use of plasma of a second gas, and removing at least a part of the first polymerized film, the oxide film, and the insulation film with the use of plasma of a third gas.