Semiconductor-on-Insulator Local Dissolution Topography Control
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Solution Overview
Problem
The existing local dissolution processes for oxide or oxynitride layers in semiconductor-on-insulator structures often result in topography defects like trenches at the mask edges, which are detrimental to component manufacturing due to high surface mobility of semiconductor atoms and are difficult to rectify with chemical-mechanical polishing without compromising the semiconductor layer's thickness and uniformity.
Innovation Solution
A process involving the formation of a nitride or oxynitride layer on exposed regions before or during the heat treatment, with controlled nitrogen atmosphere and temperature, to enhance oxygen diffusion rates and reduce surface mobility, thereby minimizing topography defects and maintaining semiconductor layer integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a mask is used to define exposed regions for local dissolution, then the precision of dissolving the oxide or oxynitride layer in determined regions is improved, but topography defects like trenches appear at the mask edges due to high surface mobility of semiconductor atoms
Solution Approach 1:
The patent changes the physical-chemical parameters of the semiconductor layer surface by forming a nitride or oxynitride layer with specific thickness (1-10 nm) and composition ratios (Nx where 0 < x ≤ 1). This parameter change modifies the surface properties to reduce atom mobility while maintaining controlled oxygen diffusion, thereby preventing trench formation at mask edges during local dissolution processes
Solution Approach 2:
The nitride or oxynitride layer acts as an intermediary between the mask and the semiconductor layer. It serves as a controlled diffusion pathway that allows oxygen to pass through at regulated rates while simultaneously suppressing the high surface mobility of semiconductor atoms that causes trench formation. The intermediary layer thus mediates between the need for precise local dissolution and the need to maintain surface topography
2Speed
If the thickness of the thin semiconductor layer is reduced to facilitate oxygen diffusion, then the oxygen diffusion rate increases, but the semiconductor layer becomes more susceptible to dewetting and topography defects
Solution Approach 1:
Instead of changing the thickness parameter of the semiconductor layer, the patent introduces a new parameter - the nitride or oxynitride layer with controlled composition (Nx where 0 < x ≤ 1) and thickness (1-10 nm). This parameter change enables enhanced oxygen diffusion through the semiconductor layer without compromising layer integrity, as the nitride/oxynitride layer provides a controlled diffusion pathway that maintains structural stability
Solution Approach 2:
The patent creates a composite structure consisting of the semiconductor layer combined with a nitride or oxynitride layer. This composite material system combines the advantages of both materials: the semiconductor layer provides the base structure while the nitride/oxynitride layer enhances oxygen diffusion capability and simultaneously suppresses surface mobility, preventing dewetting and maintaining layer integrity
3Object-affected harmful factors
If chemical-mechanical polishing is applied to remove topography defects, then the surface topography is improved, but the thickness and uniformity of the semiconductor layer are compromised
Solution Approach 1:
The patent applies preliminary anti-action by forming the nitride or oxynitride layer before the local dissolution process. This pre-formed layer prevents the formation of topography defects like trenches at mask edges by suppressing surface mobility of semiconductor atoms. By preventing the harmful effect rather than correcting it afterward, the semiconductor layer thickness and uniformity are preserved without requiring damaging polishing operations
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 improves the surface topography of the thin semiconductor layer by increasing the oxygen diffusion rate through exposed regions, reducing trench formation, and preventing dewetting, while maintaining the semiconductor layer's thickness and uniformity.
Implementation Method 1
induce at least a part of the oxygen of the layer of oxide or oxynitride to diffuse through the thin semiconductor layer
Implementation Method 2
a heat treatment is applied in an atmosphere reduced in oxygen, and under controlled temperature and duration conditions
Implementation Method 3
the nitrogen also diffuses through the thin layer of semiconductor material, so that at the end of the dissolution treatment, the oxide or oxynitride is transformed into the semiconductor material under consideration
Data Source
Figure 1~3
Figure 4~6
AI summary
The invention relates to a method for treating a semiconductor-on-insulator structure comprising the following steps: (i) forming, on the surface of the thin film (3), a mask (4) defining regions (3a) of the thin film, referred to as exposed regions, and regions (3b) covered by the mask; (ii) applying a heat treatment that induces at least some of the oxygen in the oxide or oxynitride layer (2) to diffuse through the exposed regions (3a). Before or during step (ii), a nitride or oxynitride layer (5) of the semiconductor material of the thin film (3) is formed on the exposed regions (3a), the thickness of said layer (5) being such that the ratio between the rate of oxygen diffusion through the exposed regions (3a) and through the regions (3b) covered by the mask (4) is greater than 2.