SOI Wafer Trenches for Electrostatic Chuck Release
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Solution Overview
Problem
Semiconductor wafers made of SOI substrates often stick to electrostatic chucks due to residual adsorption force, leading to issues like cracking and conveyance failure during processing, primarily because of electric charges and compressive stress from the insulating film.
Innovation Solution
The formation of trenches in the insulating film on the semiconductor substrate reduces compressive stress and allows for easier release of electric charges, preventing the wafer from sticking to the electrostatic chuck by maintaining a specific depth and aspect ratio without reaching the substrate, thus minimizing warpage and adsorption issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an electrostatic chuck is used to adsorb and hold the SOI wafer, then the wafer can be securely held during processing, but the residual adsorption force causes the wafer to stick to the chuck due to electric charges
Solution Approach 1:
The patent extracts and removes the rear insulating film from the SOI wafer structure. This removal eliminates the source of electric charge accumulation that causes residual adsorption force, allowing the wafer to be easily separated from the electrostatic chuck after processing while maintaining secure holding during processing.
Solution Approach 2:
The patent applies a preliminary action by forming trenches in the first insulating film before the wafer is processed on the electrostatic chuck. These trenches prevent electric charge accumulation during the adsorption phase, ensuring that residual adsorption force is minimized before separation is needed, thus facilitating easy wafer release.
2Stability of the object's composition
If a rear insulating film is formed on the SOI substrate, then the substrate structure is complete, but electric charges remain in the wafer causing sticking to the electrostatic chuck
Solution Approach 1:
The patent extracts and removes the rear insulating film from the SOI wafer structure. This removal eliminates the source of electric charge accumulation that causes residual adsorption force, allowing the wafer to be easily separated from the electrostatic chuck after processing while maintaining secure holding during processing.
Solution Approach 2:
The patent introduces trenches (porous structures) in the first insulating film to provide pathways for electric charge dissipation. These trenches allow charges to escape during processing, preventing charge accumulation that would otherwise cause the wafer to stick to the electrostatic chuck.
3Object-generated harmful factors
If the trench depth is increased to release electric charges, then charge dissipation improves, but the structural integrity of the insulating film may be compromised
Solution Approach 1:
The patent applies partial action by forming trenches that extend only to a specific depth (first depth) from the upper surface of the first insulating film, not completely through it. This partial penetration is sufficient to provide charge dissipation pathways while maintaining the overall structural integrity and protective function of the insulating film.
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 effectively reduces the residual adsorption force, preventing wafer sticking and related failures during processing, while maintaining the structural integrity and optical characteristics of the semiconductor device.
Implementation Method 1
A semiconductor manufacturing apparatus uses an electrostatic chuck as a way of adsorbing and holding a wafer
Data Source
AI summary
A rectangular optical waveguide, an optical phase shifter and an optical modulator each formed of a semiconductor layer are formed on an insulating film constituting an SOI wafer, and then a rear insulating film formed on a rear surface of the SOI wafer is removed. Moreover, a plurality of trenches each having a first depth from an upper surface of the insulating film are formed at a position not overlapping with the rectangular optical waveguide, the optical phase shifter and the optical modulator when seen in a plan view in the insulating film. As a result, since an electric charge can be easily released from the SOI wafer even when the SOI wafer is later mounted on the electrostatic chuck included in the semiconductor manufacturing apparatus, the electric charge is less likely to be accumulated on the rear surface of the SOI wafer.