Semiconductor Noise Reduction via Angled Ion Implantation
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Solution Overview
Problem
Existing semiconductor manufacturing methods fail to accurately form element isolation structures, leading to insufficient noise reduction due to wide impurity diffusion and unreliable channel cut region formation.
Innovation Solution
A method involving thermal oxidation of a silicon substrate using a silicon nitride film as a mask to form a silicon oxide film with a bird's beak portion, followed by angled ion implantation to create a first conductivity type impurity region under the bird's beak portion, which reduces noise by suppressing charge recombination in the semiconductor element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thermal oxidation is performed for forming a selective oxide film after ion implantation for forming a channel stop layer, then the selective oxide film can be formed, but the impurity in the channel stop layer is widely diffused and noise cannot be sufficiently reduced
Solution Approach 1:
The patent performs ion implantation for forming the channel stop layer BEFORE thermal oxidation, rather than after. This preliminary action prevents the impurity from being widely diffused during subsequent oxidation processes, thereby reducing noise while still achieving the desired channel stop function.
Solution Approach 2:
The patent changes the sequence and timing parameters of the ion implantation and thermal oxidation processes. By controlling when ion implantation occurs relative to thermal oxidation, and by controlling the oxidation conditions, the impurity diffusion is limited and noise is reduced.
2Quantity of substance
If solid phase diffusion of impurity introduced by ion implantation is performed on the surface of an element isolation silicon oxide film, then diffusion can occur, but a channel cut region may not be formed reliably and noise cannot be sufficiently reduced
Solution Approach 1:
The patent performs ion implantation to introduce impurity into the silicon substrate BEFORE forming the element isolation oxide film, rather than performing solid phase diffusion on the surface after oxide formation. This preliminary impurity introduction ensures reliable channel cut region formation underneath the oxide while limiting unwanted surface diffusion.
3Manufacturing precision
If ion implantation is performed for forming a channel stop layer, then the channel stop layer can be formed, but the impurity diffuses widely and noise reduction is insufficient
Solution Approach 1:
The patent controls the ion implantation parameters including energy, dose, and timing relative to subsequent oxidation processes. By optimizing these parameters, the impurity is confined to the desired region for channel stop functionality without excessive diffusion that would cause noise.
Solution Approach 2:
The patent creates localized impurity regions with specific concentration profiles through controlled ion implantation. The impurity is concentrated where needed for channel stop function while avoiding widespread diffusion into adjacent regions, thereby maintaining positioning precision and reducing noise.
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 allows for precise formation of the first conductivity type impurity region, effectively reducing noise in semiconductor elements and enhancing the overall performance of semiconductor apparatuses.
Implementation Method 1
thermally oxidizing a silicon substrate using as a mask a silicon nitride film disposed so as to cover a first portion of the silicon substrate without covering a second portion adjacent to the first portion, thus forming a silicon oxide film
Implementation Method 2
performing angled ion implantation into a region under the sub portion using the silicon nitride film as a mask
Data Source
AI summary
A method for manufacturing a semiconductor apparatus includes the first step of forming a silicon oxide film including a main portion on a second portion and a sub portion between a first portion and a silicon nitride film, the second step of forming a first conductivity type impurity region under the silicon oxide film, and the third step of forming a semiconductor element including a second conductivity type impurity region having an opposite conductivity to the first conductivity type impurity region in the first portion. In the second step, angled ion implantation is performed into a region under the sub portion at an implantation angle using the silicon nitride film as a mask.