Wrap-around Contact Integration Sidewall Protection
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Solution Overview
Problem
Current semiconductor manufacturing techniques face challenges in controlling parasitic capacitance and optimizing metal-semiconductor contact resistance, particularly in FinFET structures, where maximizing contact area is crucial for reducing resistance.
Innovation Solution
A wrap-around contact integration scheme is implemented, which includes sidewall protection during contact formation by depositing a conformal film on the sidewall and bottom portion of a recessed feature, followed by anisotropic and isotropic etching processes to create a cavity with a metal fill, ensuring adequate protection and increased contact area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wrap-around contact structure is used to maximize contact area, then contact resistance is reduced, but parasitic capacitance control becomes more difficult
Solution Approach 1:
The contact structure is segmented into distinct functional zones: a narrow recessed feature for minimal capacitance and a wider cavity for low resistance contact. This segmentation allows each zone to optimize its function independently, resolving the contradiction between capacitance control and resistance reduction.
Solution Approach 2:
Different regions of the contact structure have different dimensional characteristics - the recessed feature has narrow width for capacitance control while the cavity provides larger volume for resistance reduction. The protection film also has localized thickness variations to provide selective protection in different areas.
2Manufacturing precision
If anisotropic etching is used to define recessed feature width, then manufacturing precision is improved, but complete cavity formation requires additional isotropic etching steps
Solution Approach 1:
The anisotropic etching process is performed first to precisely define the recessed feature width using the protection film as a mask. This preliminary action establishes the critical dimension before the isotropic etching step creates the final cavity, separating the precision definition from the volume creation.
Solution Approach 2:
The conformal protection film serves as an intermediary element that enables the transition from anisotropic to isotropic etching. It is deposited conformally, selectively removed from the cavity bottom, and then used as an etch stop to define the recessed feature width during anisotropic etching before being removed to allow isotropic cavity formation.
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 contact resistance and enhances the contact area, addressing the challenges of parasitic capacitance control in FinFET structures by providing a robust and efficient integration method for semiconductor devices.
Implementation Method 1
depositing a conformal film on the sidewall and on the bottom portion of the recessed feature
Implementation Method 2
depositing a conformal film on the sidewall and on the bottom portion of the recessed feature
Implementation Method 3
removing the conformal film from the bottom portion in a first anisotropic etching process
Implementation Method 4
forming a cavity containing the raised contact in an isotropic etching process
Data Source
AI summary
A wrap-around contact integration scheme is described that includes sidewall protection during contact formation. A substrate processing method includes providing a substrate containing a raised contact in a first dielectric film, and a second dielectric film on the first dielectric film, where the second dielectric film has a recessed feature with a sidewall and a bottom portion above the raised contact. The method further includes depositing a conformal film on the sidewall and on the bottom portion of the recessed feature, removing the conformal film from the bottom portion in a first anisotropic etching process, where the remaining conformal film forms a protection film on the sidewall and defines a width of the recessed feature, and forming a cavity containing the raised contact in an isotropic etching process, where a width of the cavity is greater than the width of the recessed feature.