Substrate Trench Depth Adjustment via Patterned Buffering Layer
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Solution Overview
Problem
The micro loading effect in semiconductor substrate etching leads to reduced etching rates due to reactants or ions failing to reach the bottom of miniature trenches, resulting in uneven trench depths.
Innovation Solution
A method involving a patterned covering layer with alternating wider and narrower spacings, where a buffering layer is formed with thinner narrower layers etched first using halogen hydride gas, followed by fluorocarbon gas, to adjust the etching process and achieve balanced trench depths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the substrate is etched to form miniature trenches with reduced spacing, then the trench density and integration are improved, but the etching rate is reduced due to the micro loading effect
Solution Approach 1:
The patent applies preliminary action by forming a buffering layer with non-uniform thickness before the etching process. The buffering layer is designed with greater thickness in regions corresponding to narrower spacing between trenches. This preliminary structural preparation compensates for the micro loading effect that will occur during etching, ensuring that narrower trenches receive additional material protection that extends their etching time and allows reactants to reach the bottom more effectively, thereby maintaining uniform trench depths despite reduced spacing
2Ease of manufacture
If the substrate is etched with uniform buffering layer, then the process is simple, but the trench depths become uneven due to micro loading effect in narrower spacing regions
Solution Approach 1:
The patent applies local quality by creating a buffering layer with spatially varying thickness. The buffering layer has greater thickness in regions corresponding to narrower spacing between trenches and lesser thickness in regions corresponding to wider spacing. This local variation in buffering layer thickness is specifically designed to compensate for the micro loading effect that occurs predominantly in narrower spacing regions, ensuring that all trenches achieve uniform final depths despite the non-uniform etching conditions across different spacing regions
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 method improves the micro loading effect by ensuring the narrower trenches are etched earlier and deeper than wider trenches, resulting in more uniform trench depths and enhanced etching efficiency.
Implementation Method 1
Implementing a dry etching process to form a plurality of wider trenches and a plurality of narrower trenches on the substrate corresponding to the wider and the narrower buffering layers respectively
Implementation Method 2
When implementing the dry etching process to the wider and the narrower buffering layers, the gas used for the dry etching process is halogen hydride gas
Implementation Method 3
When the narrower buffering layer is removed, the gas used for the dry etching process is replaced by fluorocarbon gas to adjust the selective ratio of the dry etching process
Data Source
AI summary
A method for adjusting the trench depth of a substrate has the steps as follows. Forming a patterned covering layer on the substrate, wherein the patterned covering layer defines a wider spacing and a narrower spacing. Forming a wider buffering layer arranged in the wider spacing and a narrower buffering layer arranged in the narrower spacing. The thickness of the narrower buffering layer is thinner than the wider buffering layer. Implementing dry etching process to make the substrate corresponding to the wider and the narrower buffering layers form a plurality of trenches. When etching the wider and the narrower buffering layers, the narrower buffering layer is removed firstly, so that the substrate corresponding to the narrower buffering layer will be etched early than the substrate corresponding to the wider buffering layer.