Sacrificial Spacer Fin for Reliable Endpoint Detection in FinFET RIE
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Solution Overview
Problem
Current methods for dielectric spacer removal in finFET devices lack a reliable endpoint detection signal, making it challenging to control the spacer pull down process and prevent epitaxial semiconductor nodule formation during semiconductor fin field effect transistor fabrication.
Innovation Solution
A sacrificial spacer fin with the same pitch and height as the semiconductor fins is used, which is removed during the dielectric spacer reactive ion etch, enhancing endpoint detection and increasing the endpoint signal intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current dielectric spacer removal processes are used, then the spacer pull down process can be performed, but reliable endpoint detection signal is lacking
Solution Approach 1:
A sacrificial spacer fin is introduced as an intermediary structure during the dielectric spacer removal process. This sacrificial fin is positioned adjacent to the semiconductor fin and is removed during the spacer RIE process, generating a detectable endpoint signal when the dielectric spacer is fully removed. The intermediary structure enables reliable endpoint detection without affecting the final device structure.
Solution Approach 2:
The endpoint detection utilizes optical signal changes (analogous to color changes) by monitoring the reflectivity or light transmission characteristics during the RIE process. When the dielectric spacer is completely removed, the underlying sacrificial spacer fin exposes a distinct optical signature that provides a clear endpoint detection signal for process control.
2Manufacturing precision
If dielectric spacer removal is performed without sacrificial spacer fin, then the process structure is simpler, but endpoint detection accuracy deteriorates
Solution Approach 1:
The sacrificial spacer fin acts as a temporary, disposable structure that is intentionally created and then completely removed during the spacer RIE process. This temporary structure provides the necessary endpoint detection signal but does not remain in the final device, thus enabling precise spacer removal control without permanent complexity in the device architecture.
Solution Approach 2:
The sacrificial spacer fin is formed in advance before the dielectric spacer removal process. This preliminary action prepares the structure to generate the endpoint detection signal during spacer removal, ensuring that the detection mechanism is already in place before the critical removal operation begins.
3Measurement precision
If sacrificial spacer fin is introduced, then endpoint signal intensity increases, but process complexity increases
Solution Approach 1:
The sacrificial spacer fin serves multiple functions: it acts as a structural placeholder during spacer formation, provides the endpoint detection signal during spacer removal, and defines the precise location for spacer deposition. By consolidating these multiple functions into a single structure, the process complexity increase is minimized while achieving reliable endpoint detection.
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 method provides reliable dielectric spacer endpoint detection and improved accuracy in the spacer RIE process, allowing for sufficient space for subsequent epitaxial growth of source/drain structures in finFET devices.
Implementation Method 1
a spacer reactive ion etch is performed to the dielectric spacer material to provide a dielectric spacer on sidewall surfaces of the sacrificial gate structure, wherein during the spacer reactive ion etch exposed portions of each sacrificial spacer fin are removed
Data Source
AI summary
A method and structure to enable reliable dielectric spacer endpoint detection by utilizing a sacrificial spacer fin are provided. The sacrificial spacer fin that is employed has a same pitch as the pitch of each semiconductor fin and the same height as the dielectric spacers on the sidewalls of each semiconductor fin. Exposed portions of the sacrificial spacer fin are removed simultaneously during a dielectric spacer reactive ion etch (RIE). The presence of the sacrificial spacer fin improves the endpoint detection of the spacer RIE and increases the endpoint signal intensity.