Uniform Doping in 3D Semiconductor Active Pillars via Silicon Glass
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In three-dimensional semiconductor structures, achieving uniform doping concentration in vertically extended doped portions is challenging due to the limitations of the ion implantation process, leading to electrical property differences between devices at different heights.
Innovation Solution
A semiconductor structure and method involving n-type heavily doped portions extending vertically with uniform doping concentration, achieved by using silicon glass as a n-type dopant material, which is introduced into semi-manufactured active pillars through a thermal process, ensuring consistent doping from top to bottom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ion implantation process is used to form vertically arranged doped portions in high aspect ratio trenches, then doped portions can be formed in the trenches, but uniform doping concentration cannot be obtained in the vertical direction
Solution Approach 1:
Instead of implanting dopants from the top down through high aspect ratio trenches (conventional approach), the patent inverts the approach by first forming an insulating layer containing dopant atoms, then using chemical etching to selectively remove portions of this layer and transfer dopants to the semiconductor structure. This inversion allows uniform doping concentration to be achieved because the dopant source is now at the bottom rather than the top.
Solution Approach 2:
The patent introduces an insulating layer as an intermediary medium that contains the dopant atoms. This intermediary layer serves as a reservoir that releases dopants through chemical etching, enabling uniform doping concentration distribution in the vertical direction while avoiding the limitations of direct ion implantation through high aspect ratio trenches.
2Manufacturing precision
If doped portions are formed by vertical implantation from top, then doping can be achieved, but doping concentration near top is higher than near bottom
Solution Approach 1:
The patent inverts the doping approach by placing the dopant source at the bottom (insulating layer) rather than at the top. Chemical etching removes the insulating layer material and transfers dopants uniformly throughout the vertical height, achieving uniform doping concentration and consistent electrical properties across all devices in the stack.
Solution Approach 2:
The patent changes the physical and chemical parameters of the doping process by using chemical etching instead of ion implantation. This parameter change enables uniform dopant distribution because the chemical etching process progresses uniformly through the insulating layer, releasing dopants at a consistent rate throughout the vertical dimension.
3Length of moving object
If high aspect ratio trenches are used to separate stacks, then 3D structure can be achieved, but uniform doping in vertical direction becomes difficult
Solution Approach 1:
The patent uses an insulating layer as an intermediary that spans the entire vertical height of the high aspect ratio trenches. This intermediary contains dopant atoms that are uniformly distributed, and chemical etching transfers these dopants uniformly throughout the vertical dimension, achieving doping uniformity despite the large vertical height of the stacks.
Solution Approach 2:
The patent changes the doping mechanism from physical ion implantation (which is sensitive to trench aspect ratio) to chemical etching-mediated dopant transfer. This parameter change allows uniform doping concentration to be achieved even in high aspect ratio trenches because the chemical process is not limited by the geometric constraints that affect ion implantation.
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 ensures uniform doping concentration along the vertical direction, addressing the electrical property disparities and enhancing the consistency of semiconductor devices.
Implementation Method 1
n-type heavily doped portions are formed between the semi-manufactured active pillars and the insulating material by conducting a thermal process that drives the element which is applicable as a n-type dopant into the semi-manufactured active pillars
Data Source
AI summary
A semiconductor structure includes a plurality of stacks, a plurality of active pillars, and an insulating material. The stacks are separated from each other by a plurality of trenches. The active pillars are disposed in the trenches and separated from each other in each of the trenches. Each of the active pillars comprises two n-type heavily doped portions at two sides thereof. Each of the two n-type heavily doped portions extends in a substantially vertical direction. Each of the two n-type heavily doped portions connects corresponding two stacks of the plurality of stack. The insulating material is located in remaining spaces of the trenches between the active pillars. The insulating material is a silicon glass comprising an element which is applicable as a n-type dopant.