Composite Hard Mask Layout for STI During Interposer Etching
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Solution Overview
Problem
As semiconductor devices continue to integrate more components into a given area through reduced minimum feature sizes, challenges arise in protecting Shallow Trench Isolation (STI) regions during the removal of disposable interposers, leading to potential damage and inefficiencies in the manufacturing process.
Innovation Solution
A composite hard mask structure is formed over STI regions, comprising multiple layers with controlled thicknesses and materials to protect STI regions during the removal of disposable interposers, using deposition and etching processes to ensure precise and selective removal of sacrificial layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If minimum feature sizes are reduced to increase integration density, then more components can be integrated into a given area, but additional problems arise including difficulty in protecting STI regions during disposable interposer removal
Solution Approach 1:
A hard mask layer is formed over the STI region before removing the disposable interposer. This preliminary protective action prevents damage to the STI region during the subsequent etching process, resolving the contradiction between reduced feature sizes and STI protection needs
Solution Approach 2:
The hard mask layer acts as an intermediary protective barrier between the etching chemical and the STI region. This mediator allows the etching process to proceed while protecting the STI region from direct exposure to harmful chemicals
2Reliability
If a hard mask layer is formed over STI regions to protect them, then STI regions are safeguarded during disposable interposer removal, but the manufacturing process becomes more complex
Solution Approach 1:
The hard mask layer serves multiple functions: it protects the STI region during etching, defines the etching boundaries, and can serve as an etch stop layer. This multi-functionality reduces the need for additional separate protective structures
Solution Approach 2:
The hard mask layer is formed from materials with specific properties (such as silicon nitride or carbon) that provide both protection and etching selectivity. The use of composite material structures enables a single layer to perform multiple protective and process control functions
3Productivity
If disposable interposers are removed using etching chemicals, then the interposers are efficiently removed, but STI regions may be damaged by the chemicals
Solution Approach 1:
The hard mask layer serves as a protective intermediary that allows etching chemicals to efficiently remove the disposable interposer while preventing the chemicals from directly contacting and damaging the STI region
Solution Approach 2:
The hard mask layer is selectively removed after the disposable interposer is etched away, extracting the protective function when needed and allowing the STI region to be exposed for subsequent processing steps
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 composite hard mask effectively safeguards STI regions, enabling efficient and precise patterning of semiconductor structures, enhancing manufacturing yield and reliability.
Implementation Method 1
A composite hard mask structure is formed over STI regions, comprising multiple layers with controlled thicknesses and materials to protect STI regions during the removal of disposable interposers, using deposition and etching processes
Implementation Method 2
using deposition and etching processes to ensure precise and selective removal of sacrificial layers
Data Source
AI summary
A method includes forming a shallow trench isolation region aside of a protruding fin, and forming a composite hard mask over the shallow trench isolation region. The composite hard mask is formed through a plurality of deposition processes and a plurality of etching processes. The method further includes forming a dummy gate stack over the protruding fin, removing a sacrificial layer in the protruding fin to leave a space between a first and a second semiconductor nanostructures that are in the protruding fin, forming a disposable interposer in the space, removing the dummy gate stack, and removing the disposable interposer using an etching chemical. When the disposable interposer is removed, the composite hard mask is exposed to the etching chemical, and a bottom portion of the composite hard mask remains after the disposable interposer is removed. A gate stack is then formed to fill the space.