Through-Chip Via Electrode Formation Using Selective Wet Etching
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Solution Overview
Problem
The existing methods for forming through-chip via electrodes in semiconductor devices are costly due to the use of chemical-mechanical polishing (CMP), which consumes expensive chemical slurry and has a low polishing rate.
Innovation Solution
A method that forms through-chip via electrodes using wet etching to remove unwanted electrode material and barrier metal layers outside the holes, eliminating the need for CMP and reducing material costs by using a metal lining layer that can be selectively etched without affecting the electrode material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If chemical-mechanical polishing (CMP) is used to remove electrode material and barrier metal outside the holes, then the unwanted material is removed, but the production cost increases due to expensive chemical slurry consumption
Solution Approach 1:
The patent divides the barrier metal layer into two functional parts: an inner barrier metal layer (first barrier metal layer) that remains to prevent diffusion, and an outer barrier metal layer (second barrier metal layer) that is selectively removed by wet etching. This segmentation allows the outer layer to serve as a sacrificial etch stop, eliminating the need for expensive CMP slurry while maintaining the protective function of the inner layer.
Solution Approach 2:
The patent introduces an intermediary substance (etch stopper layer or sacrificial layer) between the barrier metal layer and the electrode material. This intermediary layer is selectively removed by wet etching to expose the inner barrier metal layer, serving as a mediator that enables selective material removal without requiring CMP process and its expensive slurry.
2Reliability
If multiple barrier metal layers are formed to prevent diffusion and ensure tight contact, then the electrode reliability improves, but the manufacturing complexity increases
Solution Approach 1:
The barrier metal layer is segmented into functional zones: the first barrier metal layer provides diffusion prevention and electrical contact, while the second barrier metal layer serves as a sacrificial etch stop. This segmentation achieves reliable electrode contact through the inner layer while simplifying manufacturing by using the outer layer as a self-removing template.
Solution Approach 2:
The patent changes the chemical composition parameters of the barrier metal layers to create selective etchability. The second barrier metal layer has different etch resistance properties compared to the first barrier metal layer, allowing selective removal by wet etching while maintaining the protective function of the inner layer.
3Reliability
If the barrier metal layer thickness is increased to ensure tight contact, then the electrode reliability improves, but the electrical resistance increases
Solution Approach 1:
The barrier metal structure is segmented into a thin first barrier metal layer for electrical contact and a thicker second barrier metal layer for etch protection. This segmentation allows the contact layer to be optimized for low resistance while the protective layer provides sufficient thickness for reliable processing.
Solution Approach 2:
Different regions of the barrier metal structure have different thicknesses and compositions optimized for their specific functions: the inner barrier metal layer has properties optimized for electrical contact and diffusion prevention, while the outer barrier metal layer has properties optimized for etch resistance and sacrificial removal.
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 reduces production costs by eliminating the need for chemical slurry and allows for the formation of electrodes with lower electrical resistance by optimizing the thickness of the barrier metal layer, resulting in a more efficient and cost-effective semiconductor device manufacturing process.
Implementation Method 1
removing the part of the electrode material layer exterior to the hole by wet etching, leaving an electrode embedded in the hole; and removing the part of the metal lining layer exterior to the hole by wet etching
Implementation Method 2
the holes are filled with the copper or another electrode material by an electroplating process
Data Source
AI summary
An electrode is formed in a hole extending partway into the substrate of a semiconductor device by depositing an insulating film and a barrier metal layer on the substrate surface and the interior of the hole, then filling the hole with a layer of electrode material that also covers the substrate surface. Next, the electrode material exterior to the hole is removed by wet etching, using an etchant that does not etch the barrier metal. The barrier metal exterior to the hole is then removed by wet etching, using an etchant that does not etch the electrode material. This process eliminates the need for expensive chemical mechanical polishing.