Oxide Semiconductor Transistor Cleaning for Etch Residue Control
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Solution Overview
Problem
Semiconductor devices incorporating oxide semiconductors face reliability issues due to residue contamination from etching processes, leading to degraded electrical characteristics and reduced yield.
Innovation Solution
Implement a residue removal step using water, alkaline solutions, or plasma treatment to clean the surface of oxide semiconductor films and gate electrode layers after forming source and drain electrode layers, ensuring a surface density of contaminants like halogen, boron, phosphorus, aluminum, iron, or carbon is below 1×10^13 atoms/cm^2 or 5×10^18 atoms/cm^3.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If etching process is used to form metal layers, then metal layers are successfully formed, but residue contamination occurs on oxide semiconductor film and gate electrode layer surfaces
Solution Approach 1:
A residue removal step is performed after the etching process to eliminate etchant residues from the metal layer surfaces before subsequent processing steps. This preliminary cleaning action prevents residue-induced defects in later stages such as oxide semiconductor film formation and device operation.
Solution Approach 2:
The etching residue, which is initially a harmful contaminant, is systematically removed through dedicated cleaning steps including organic solvent treatment and plasma treatment. By converting the harmful residue into a removable substance, the process transforms the etching step's harmful effect into a manageable intermediate state that can be eliminated.
2Adaptability or versatility
If multiple thin films are complicatedly stacked to form semiconductor device, then device functionality is achieved, but manufacturing process complexity increases causing shape defects and electrical characteristic degradation
Solution Approach 1:
The manufacturing process is divided into distinct segments with dedicated residue removal steps positioned at critical transition points. Rather than treating the entire complex process as a single unit, the method segments the workflow to target residue contamination at specific stages where it most critically impacts subsequent film formation and device performance.
Solution Approach 2:
Residue removal steps act as intermediary processes between the etching step and subsequent film deposition steps. These intermediary cleaning operations mediate the transition from a contaminated state to a clean state, ensuring that each subsequent layer is formed on a properly prepared surface without residue-induced defects.
3Reliability
If residue removal step is added to clean surfaces, then electrical characteristics are improved, but manufacturing time and process steps increase
Solution Approach 1:
Rather than implementing continuous or excessive cleaning throughout the entire manufacturing process, the method applies residue removal steps selectively at critical points where residue contamination would most significantly impact device performance. This partial action approach removes residues when necessary while avoiding unnecessary processing steps.
Solution Approach 2:
The residue removal process utilizes controlled parameters including specific organic solvents, plasma power levels, and treatment durations optimized to achieve effective residue elimination within minimal time. By carefully controlling these parameters, the process achieves thorough cleaning without excessive processing time that would reduce productivity.
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 results in a highly reliable semiconductor device with stable electrical characteristics and improved productivity by preventing residue contamination, thereby enhancing the device's performance and manufacturing efficiency.
Implementation Method 1
Treatment using water or an alkaline solution or plasma treatment can be performed as the residue removal step. Specifically, treatment using water or a tetramethylammonium hydroxide (TMAH) solution or plasma treatment using oxygen, dinitrogen monoxide, or a rare gas (typically argon) can be favorably used.
Data Source
AI summary
When a semiconductor device including a transistor in which a gate electrode layer, a gate insulating film, and an oxide semiconductor film are stacked and a source and drain electrode layers are provided in contact with the oxide semiconductor film is manufactured, after the formation of the gate electrode layer or the source and drain electrode layers by an etching step, a step of removing a residue remaining by the etching step and existing on a surface of the gate electrode layer or a surface of the oxide semiconductor film and in the vicinity of the surface is performed. The surface density of the residue on the surface of the oxide semiconductor film or the gate electrode layer can be 1×1013 atoms/cm2 or lower.