Semiconductor Trench Uniformity via Localized Insulation Film
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Solution Overview
Problem
The Bosch process for forming trenches in silicon often results in a concave-convex shape of the trench side surface due to isotropic etching, leading to stress concentration and reduced reliability of semiconductor devices, and the uniformity of moisture-proof films is difficult to maintain, especially when metal wiring is present.
Innovation Solution
A semiconductor device and manufacturing method where a low electric conductivity portion is applied on the surface structure portion, covering the metal layer, to improve the uniformity of the trench side surface even when the distance from the trench to the metal layer changes, using a Bosch process with a resist mask and insulation film to control etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the Bosch process is used to form trenches in silicon, then high aspect ratio trenches can be formed, but the trench side surface develops a concave-convex shape due to isotropic etching
Solution Approach 1:
The patent applies a low electric conductivity portion (insulation film) specifically to areas with metal wiring that are distant from the trench, rather than uniformly across the entire surface. This localized modification allows the metal wiring to serve as an etching stop without causing isotropic etching effects on the trench side surface, thereby maintaining trench shape uniformity while preserving the benefits of the Bosch process for forming high aspect ratio trenches.
2Reliability
If metal wiring is present distant from the trench, then electrical connectivity is maintained, but isotropic etching causes concave-convex shapes and notches on the trench side surface
Solution Approach 1:
The patent introduces a low electric conductivity portion (insulation film) as an intermediary layer between the metal wiring and the silicon surface in areas distant from the trench. This intermediary prevents the metal wiring from directly causing isotropic etching effects on the trench side surface, while still allowing the metal wiring to maintain its electrical connectivity function. The insulation film acts as a mediator that decouples the harmful isotropic etching effect from the useful electrical connectivity function.
3Productivity
If the Bosch process is used with metal wiring present, then trenches can be formed, but the uniformity of moisture-proof films becomes difficult to maintain
Solution Approach 1:
The patent applies the low electric conductivity portion (insulation film) locally to areas with metal wiring that are distant from the trench, rather than uniformly across the entire surface. This localized approach maintains trench formation capability through the Bosch process while preventing isotropic etching effects that would compromise moisture-proof film uniformity in critical areas.
4Ease of manufacture
If isotropic etching occurs during Bosch process, then etching can proceed, but stress concentration occurs and device reliability reduces
Solution Approach 1:
The patent converts the potentially harmful effect of metal wiring causing isotropic etching into a beneficial situation by applying a low electric conductivity portion (insulation film) in strategic locations. This prevents the metal wiring from directly causing stress concentration and reliability issues, while still allowing the Bosch process to proceed effectively for trench 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 enhances the uniformity of the trench side surface, reduces stress concentration, and improves the reliability of semiconductor devices by maintaining consistent film quality and productivity.
Implementation Method 1
positive ions in the plasma are attracted to the metal layer, migrate along the metal layer, and reach the resist, causing isotropic etching
Implementation Method 2
positive ions in the plasma are attracted to the metal layer
Implementation Method 3
a resist is disposed on the silicon layer and the metal layer
Implementation Method 4
The Bosch process is a method of forming trenches with a high aspect ratio by etching to proceed milling the bottom of a trench while protecting the sidewall of the trench with a protection film
Data Source
AI summary
A semiconductor device includes: a silicon layer in which a trench is disposed; a surface structure portion disposed on the silicon layer at a position distant from the trench and having a surface provided by a metal layer; and a low electric conductivity portion disposed on the surface of the metal layer or in a part of the resist disposed on the trench side of the metal layer, and having an electric conductivity lower than at least a part of the metal layer covering a trench side portion of the surface of the metal layer.