TSV Polymer Residue Removal via Segmented Cleaning
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Solution Overview
Problem
The Bosch process for forming high aspect ratio through silicon vias (TSVs) results in silicon-containing fluorocarbon polymer residues that are difficult to remove, contaminating the via opening and affecting the reliability of the TSV.
Innovation Solution
A series of processes including wet cleans, ash processes, and wet etches are employed to progressively remove the polymer residues, followed by a conductive fill, ensuring the TSV is free from contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the Bosch process is used to form high aspect ratio TSVs, then the via opening can be etched successfully, but silicon-containing fluorocarbon polymer residues are deposited on the sidewalls and bottom of the via opening
Solution Approach 1:
The patent segments the polymer removal process into multiple distinct stages: wet cleaning to remove bulk polymer, ashing to oxidize and remove residues, and HF vapor treatments to selectively remove silicon-containing fluorocarbon polymers. Each stage targets different aspects of polymer contamination, collectively achieving complete removal while preserving the via opening structure.
Solution Approach 2:
The patent introduces HF vapor as an intermediary substance that selectively reacts with silicon-containing fluorocarbon polymer residues without significantly affecting the silicon dioxide layer or metal fill materials. This intermediary enables selective removal of harmful polymer deposits while preserving the functional structures within the via opening.
2Ease of manufacture
If polymer residues are not removed, then the process is simpler, but the TSV reliability is compromised due to contamination
Solution Approach 1:
The patent performs preliminary polymer removal actions immediately after via opening formation, before metal fill deposition. By removing polymer residues in advance through wet cleaning, ashing, and HF vapor treatments, the process ensures that no contamination is introduced into the subsequent fill process, thereby guaranteeing TSV reliability without compromising overall process simplicity.
Solution Approach 2:
The patent implements a continuous sequence of polymer removal actions (wet clean → ash → HF vapor → additional ash cycles) that progressively eliminate polymer residues at different stages of the process. This continuous action ensures complete polymer removal throughout the manufacturing sequence, maintaining both process efficiency and TSV reliability.
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 effectively removes residual polymers, ensuring a reliable and contamination-free conductive TSV fill, enhancing the integrity of the TSV formation process.
Implementation Method 1
performing a wet clean to remove a first portion of the polymer
Implementation Method 2
performing a first ash process to remove a second portion of the polymer
Implementation Method 3
performing a first wet etch process to remove a third portion of the polymer and the carbon containing oxide
Implementation Method 4
form a first carbon containing oxide along portions of the sidewalls by pulling silicon and carbon from the substrate
Data Source
AI summary
A method of forming a through silicon via includes forming a via opening in a substrate using a hard mask, wherein a polymer is formed in the via opening. A first wet clean removes a first portion of the polymer and forms a first carbon containing oxide along portions of the sidewalls. A first ash process modifies the first carbon containing oxide and removes a second portion of the polymer. A first wet etch removes the modified first carbon containing oxide and a third portion of the polymer. A second ash process forms a second carbon containing oxide along at least a portion of the sidewalls. A second wet etch process removes the second carbon containing oxide and a fourth portions of the polymer. A third ash process forms a third carbon containing oxide along portions of the sidewalls and removes any remaining portions of the polymer.