Dummy Stacked Structures Around TSVs to Block Lateral Moisture Spread
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Solution Overview
Problem
Conventional methods for forming Through-Silicon Vias (TSVs) face challenges in effectively removing moisture from dielectric layers during the TSV process, leading to reduced efficiency and potential dielectric degradation.
Innovation Solution
The formation of dummy stacked structures around TSVs, which act as outgassing tunnels and moisture-blocking features, is introduced to facilitate moisture removal during the baking process, ensuring effective moisture dissipation and preventing lateral moisture spread.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional TSV formation methods are used, then the TSV structure is formed, but moisture remains trapped in dielectric layers causing dielectric degradation
Solution Approach 1:
The dielectric layer is segmented by creating vertical channels (dummy stacked structures) that divide the continuous dielectric material into separated regions. This segmentation allows moisture to be channeled out through the vertical pathways rather than being trapped in the bulk dielectric material, resolving the contradiction between maintaining dielectric integrity and removing moisture.
Solution Approach 2:
The dummy stacked structures act as intermediary elements between the trapped moisture in the dielectric layers and the external environment. These structures serve as intermediate pathways that facilitate moisture transport from the dielectric interior to the exterior without requiring direct modification of the dielectric material properties, thus protecting dielectric integrity while enabling moisture removal.
2Reliability
If dummy stacked structures are added around TSVs, then moisture removal is enhanced, but device complexity increases
Solution Approach 1:
The dummy stacked structures serve multiple functions simultaneously: they act as moisture outgassing pathways during baking, provide structural support around TSVs, and maintain dielectric layer integrity. By combining multiple functions into a single structural element, the patent enhances moisture removal effectiveness without proportionally increasing device complexity.
Solution Approach 2:
The dummy stacked structures are sacrificial elements that are formed temporarily to facilitate moisture removal during the baking process. After serving their primary function of enabling moisture dissipation, these structures can be removed or integrated into the final device architecture, allowing the complexity to be justified by the critical moisture removal function they performed during manufacturing.
3Quantity of substance
If baking process is performed to remove moisture, then moisture is removed from dielectric layers, but lateral moisture spread occurs
Solution Approach 1:
The patent transitions the moisture removal approach from a lateral/diffusive process to a vertical/channelled process. By introducing vertical dummy stacked structures, moisture is directed to move upward through defined pathways rather than spreading laterally through the dielectric layers during baking. This dimensional change in moisture transport direction effectively prevents lateral moisture spread while achieving moisture removal.
Solution Approach 2:
The dummy stacked structures create localized moisture removal pathways at specific locations around the TSVs. Rather than relying on uniform lateral moisture diffusion throughout the dielectric layers, the invention establishes concentrated vertical outgassing channels at critical locations, enabling targeted moisture removal that prevents lateral moisture migration to surrounding areas.
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
The dummy stacked structures enhance the effectiveness of moisture removal, reducing dielectric degradation and maintaining the integrity of the dielectric layers, thereby improving the reliability and performance of TSVs.
Implementation Method 1
The dummy stacked structures are formed in the dielectric layers, and function as outgassing tunnels for outgassing moisture from the through-via openings during a baking process
Implementation Method 2
function as outgassing tunnels for outgassing moisture from the through-via openings during a baking process, thereby preventing lateral outgassing of moisture in the dielectric layers
Data Source
AI summary
A method includes forming a plurality of low-k dielectric layers over a semiconductor substrate, forming a first plurality of dummy stacked structures extending into at least one of the plurality of low-k dielectric layers, forming a plurality of non-low-k dielectric layers over the plurality of low-k dielectric layers, and forming a second plurality of dummy stacked structures extending into the plurality of non-low-k dielectric layers. The second plurality of dummy stacked structures are over and connected to corresponding ones of the first plurality of dummy stacked structures. The method further includes etching the plurality of non-low-k dielectric layers, the plurality of low-k dielectric layers, and the semiconductor substrate to form a via opening. The via opening is encircled by the first plurality of dummy stacked structures and the second plurality of dummy stacked structures. The via opening is then filled to form a through-via.