Metal-Coated Processing Head for Straight Deep MacEtch Features
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Solution Overview
Problem
Conventional MacEtch processes struggle to form deep, straight patterns of features in semiconductor substrates due to variations in etching direction, particularly in deep etch processes like through silicon vias, leading to bent holes and limited control over the etching process.
Innovation Solution
The use of a metal-coated processing head with one or more metal surfaces to catalyze MacEtch reactions at the interface between the processing head and the substrate surface, allowing precise control over the etching process by controlling the movement of the processing head and substrate, enabling the formation of deep, straight holes, trenches, and unique structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If conventional MacEtch process is used to etch deep features, then etching depth can be achieved, but etching direction control deteriorates leading to bent holes
Solution Approach 1:
A movable processing head with metal-coated tips is introduced as an intermediary catalyst carrier. The metal coating (e.g., Au, Ag, Pt, Pd) on the processing head tips serves as the catalyst that mediates the MacEtch reaction, allowing the substrate to be etched without requiring direct metal deposition on the substrate surface. This intermediary approach enables deep etching while maintaining directional control through mechanical positioning.
Solution Approach 2:
The processing head is designed to be movable relative to the substrate, allowing dynamic adjustment of the catalyst position during the etching process. This dynamic positioning capability enables precise control over etching direction and depth, preventing the formation of bent holes while achieving the required etching depth for through-silicon vias and other deep features.
2Ease of manufacture
If noble metal catalyst is deposited on substrate surface for MacEtch, then catalytic effect is achieved, but subsequent metal removal steps are required
Solution Approach 1:
The catalyst (noble metal coating) is extracted from the substrate surface and transferred to a separate movable processing head. By removing the catalyst from the substrate and placing it on the processing head, the need for subsequent metal removal steps is eliminated. The catalyst can be easily detached by simply removing the processing head after etching, thereby improving productivity without sacrificing the catalytic effect.
3Length of stationary object
If prolonged etching is performed to achieve deep features, then etching depth increases, but variations in etching direction occur
Solution Approach 1:
The system incorporates feedback control through precise positioning mechanisms that monitor and adjust the position of the movable processing head during etching. This feedback ensures that the catalyst remains correctly positioned relative to the etch front, maintaining consistent etching direction even during prolonged etching operations required for deep feature fabrication.
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 provides greater control over the etching process, allowing for the formation of deep, straight holes and trenches, as well as angled and horizontal features, which were previously unattainable with conventional MacEtch processes, while eliminating the need for subsequent metal removal steps.
Implementation Method 1
The metal surfaces provided on the processing head catalyze the reduction of the oxidant in the etch solution to generate free holes, which are injected into portions of the substrate surface directly underlying the metal surfaces of the processing head
Implementation Method 2
The noble metal deposited onto the substrate surface catalyzes the reduction of the oxidant, producing electron holes (h+) that are injected into the valence band of the substrate. The presence of the electron holes changes the oxidation state of the Si underlying the noble metal catalyst and enables the oxidation and selective removal of Si in the acidic etch solution
Data Source
AI summary
Various embodiments of wet processing systems and methods that utilize metal assisted chemical etching (MacEtch) to process a semiconductor substrate are provided herein. The disclosed embodiments utilize a processing head having one or more metal surfaces (otherwise referred to herein as a metal-coated processing head) to catalyze the MacEtch reactions that occur at the interface between the metal surface(s) of the processing head and the surface of a semiconductor substrate when the substrate surface is exposed to an etch solution. The metal-coated processing head can be used to perform a wide variety of MacEtch processes on the substrate surface and/or within the semiconductor substrate. For example, the metal-coated processing head can be used to etch features (such as, e.g., holes, trenches, circular disks, etc.) within the semiconductor substrate, or remove high points on substrate surface to smooth the substrate surface.