Capacitor Substrate Recesses via MacEtch
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Solution Overview
Problem
Current metal-assisted chemical etching (MacEtch) methods face challenges in forming high-aspect-ratio recesses on semiconductor substrates without causing short circuits or reducing electric capacitance, particularly due to the progression of etching in the in-plane direction and the difficulty in forming a stacked structure with dielectric and conductive layers within the recesses.
Innovation Solution
A structural body with a conductive substrate having a main surface with distinct regions, including a first region with recesses and a second region lower in height, where a catalyst layer containing a noble metal is applied to the first region, and the substrate is etched using an oxidizer and hydrogen fluoride, while a groove is introduced to restrict in-plane etching and enhance the formation of a porous structure between the regions, allowing for a larger electric capacitance without short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metal-assisted chemical etching is used to form high-aspect-ratio recesses, then the electric capacitance is increased, but in-plane etching progression causes short circuits between adjacent recesses
Solution Approach 1:
The substrate surface is divided into distinct first and second regions with different heights, creating physical separation between adjacent recesses. This segmentation prevents in-plane etching progression from causing short circuits while maintaining high electric capacitance through controlled vertical etching in each isolated recess.
Solution Approach 2:
A groove structure acts as an intermediary element between adjacent recesses, physically blocking the propagation of in-plane etching. This intermediary structure allows each recess to maintain its high-aspect-ratio geometry and capacitance while preventing harmful lateral etching from connecting adjacent structures.
2Quantity of substance
If deep recesses are formed to increase capacitance, then the electric capacitance is increased, but the stacked structure formation becomes difficult
Solution Approach 1:
The groove structure is formed preliminarily before depositing the stacked structure of dielectric and conductive layers. This preliminary action creates pre-defined cavities and pathways that guide the subsequent formation of the stacked structure, making it easier to achieve proper layer alignment and integration within deep recesses without requiring complex post-etch processing.
3Length of moving object
If in-plane etching is allowed to proceed, then the recess depth is increased, but the etching progresses laterally causing short circuits
Solution Approach 1:
Different regions of the substrate are given different properties: the first region contains deep recesses for high capacitance, while the second region remains at original height to serve as a barrier. This local quality differentiation allows selective vertical etching in recess areas while preventing lateral etching propagation through the elevated second region boundaries.
Solution Approach 2:
The solution transitions from controlling etching in two dimensions (vertical depth and lateral width) to primarily controlling vertical etching while using the third dimension (height difference between first and second regions) to prevent lateral propagation. The groove creates a height-based barrier that confines etching to the vertical dimension only.
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 effectively forms recesses with controlled etching, preventing short circuits and enabling a larger electric capacitance by restricting in-plane etching and ensuring the integrity of the dielectric and conductive layers within the recesses, thus improving the manufacturing process for capacitors.
Implementation Method 1
Metal-assisted chemical etching (MacEtch) is a method of etching a semiconductor surface using a noble metal as a catalyst
Implementation Method 2
etching the substrate with an etching agent containing an oxidizer and hydrogen fluoride
Data Source
AI summary
A structural body according to an embodiment includes a conductive substrate. A main surface of the conductive substrate includes a first region and a second region adjacent to the first region and lower in height than the first region. The first region is provided with one or more recesses having a bottom, a position of which is lower than a position of the second region. A surface region of the conductive substrate on a side of the main surface includes a porous structure at a position between the second region and the one or more recesses.