Carbon Hardmask for FinFET Doping
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Solution Overview
Problem
Conventional ion implantation processes for FinFET devices cause amorphization of the fin structure, which is not fully remedied by post-implant processes, especially as the fin width scales to 20 nm or less, and precludes the use of photoresist at higher temperatures, necessitating new processing methods for 3D devices.
Innovation Solution
A method involving a carbon-based hardmask and hydrogen-based etchant excluding oxygen and fluorine species is used to selectively expose fin structures, allowing high-temperature ion implantation to introduce dopants while maintaining a single crystalline state, employing a combination of etching and implantation techniques to prevent amorphization and enable precise doping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ion implantation is performed at conventional temperatures with photoresist masking, then selective doping is achieved, but the fin structure undergoes excessive amorphization that cannot be fully remedied by post-implant processes
Solution Approach 1:
The patent raises the substrate temperature during ion implantation from conventional low temperatures to elevated temperatures (e.g., 400-600°C or higher). This parameter change prevents excessive amorphization of the fin structure by maintaining it in a crystalline state during implantation, thereby preserving structural integrity while still achieving precise selective doping through the carbon hardmask pattern.
Solution Approach 2:
The patent uses a carbon-based hardmask layer that is deposited conformally on the fin structure and then selectively removed after serving its masking function. This disposable hardmask enables high-temperature implantation without requiring temperature-sensitive photoresist, and can be completely removed after doping without leaving residues that would affect device performance.
2Stability of the object's composition
If ion implantation is performed at higher temperatures to avoid amorphization, then crystalline structure is maintained, but photoresist cannot be used as a mask
Solution Approach 1:
The patent employs a carbon-based hardmask that is specifically chosen for its ability to withstand high implantation temperatures unlike photoresist. This hardmask is deposited conformally, patterned, and then completely removed after serving its masking function. Its disposability after use simplifies the overall process by eliminating the need for temperature-sensitive photoresist and complex resist removal steps.
Solution Approach 2:
The patent changes the masking material from organic photoresist to inorganic carbon-based hardmask, which fundamentally alters the temperature compatibility parameter. This material substitution enables the process to be performed at elevated temperatures (400-600°C or higher) while maintaining ease of manufacture through conformal deposition and simple pattern transfer techniques.
3Length of moving object
If fin width is scaled to 20 nm or less to increase circuit density, then device miniaturization is achieved, but amorphization becomes more severe and harder to remedy
Solution Approach 1:
The patent performs ion implantation at elevated temperatures as a preliminary action before any post-implant annealing or rapid thermal processing. By maintaining high substrate temperature during the implantation itself, the fin structure remains in a crystalline state throughout the doping process, preventing amorphization from occurring in the first place. This eliminates the need for subsequent remedial annealing processes that would be particularly damaging to ultra-narrow fins.
Solution Approach 2:
The patent fundamentally changes the temperature parameter during ion implantation from conventional low temperatures to elevated temperatures (400-600°C or higher). This parameter change is particularly critical for ultra-narrow fins (20 nm or less) as it prevents the severe amorphization that would otherwise occur during implantation of such narrow structures, maintaining crystalline integrity throughout the process.
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 ensures the formation of single crystalline fin structures with improved crystalline quality and allows for precise doping without excessive amorphization, enhancing the manufacturing efficiency and performance of FinFET devices by maintaining the fin structure's integrity during high-temperature processing.
Implementation Method 1
etching a selected portion of the film by exposing the selected portion of the film to an etchant containing hydrogen species
Implementation Method 2
In this process, dopants having desired species may be directed toward the fin structure in a form of ions, and implanted therein
Data Source
AI summary
A method to selectively process a three dimensional device, comprising providing a substrate having a first surface that extends horizontally, the substrate comprising a structure containing a second surface that extends vertically from the first surface; providing a film on the substrate, the film comprising carbon species; and etching a selected portion of the film by exposing the selected portion of the film to an etchant containing hydrogen species, where the etchant excludes oxygen species and fluorine species.