Electrohydrodynamic Printing for Photoresist-Free Metal Features
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Solution Overview
Problem
The conventional process for forming fine line interconnects and metal features in semiconductor devices is complex, time-consuming, and costly, requiring multiple specialized pieces of equipment and processing steps, making it difficult to adapt to different substrate types or designs and limiting the ability to run tests or produce prototype substrates.
Innovation Solution
The method involves electrohydrodynamic ejection printing and electroplating using inks with electroplating additives that selectively adsorb onto a substrate, enabling preferential metal deposition rates at printed versus non-printed areas, allowing for photoresist-free formation of metal features, which simplifies the process and reduces capital and processing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photoresist-based processes are used to form metal features, then metal features can be formed with controlled deposition, but the process becomes complex and requires multiple specialized equipment and processing steps
Solution Approach 1:
The patent extracts and eliminates the photoresist layer from the conventional metallization process. By directly printing electroplating additives onto the seed layer, the process removes the photoresist application, patterning, and stripping steps, significantly simplifying the overall process while maintaining metal feature formation capability
Solution Approach 2:
The patent applies electroplating additives directly to the seed layer before electroplating, creating predetermined patterns of plating acceleration or inhibition. This preliminary patterning action eliminates the need for subsequent photoresist-based patterning steps, reducing process complexity while ensuring precise metal feature formation
2Manufacturing precision
If multiple processing steps are used for metallization, then metal features can be formed with high precision, but the fabrication time and processing costs increase
Solution Approach 1:
The patent merges the patterning function and the electroplating preparation into a single step by printing electroplating additives directly onto the seed layer. This consolidation eliminates multiple sequential steps (photoresist application, exposure, development, stripping) while maintaining the precision needed for metal feature formation, thereby reducing fabrication time
3Manufacturing precision
If conventional metallization processes are used, then metal features can be formed, but the capital and processing costs are high due to multiple specialized equipment requirements
Solution Approach 1:
The patent employs a multi-functional approach where the printed electroplating additives serve both as the patterning mechanism and as the electroplating catalyst. This single material performs multiple functions that previously required separate photoresist layers and processing equipment, reducing both capital equipment costs and processing expenses while maintaining metal feature formation precision
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 significantly simplifies the fabrication process, reduces the number of required processing apparatuses, and lowers costs by enabling the formation of fine line interconnects and metal features with high accuracy and precision without the need for many conventional processing steps.
Implementation Method 1
the electroplating additive includes an accelerator or an inhibitor, and where the electroplating additive strongly adsorbs onto the seed layer
Implementation Method 2
electroplating metal on the substrate through a preferential deposition that provides a first deposition rate at locations where the electroplating additive from the ink is present and a second deposition rate at locations where the electroplating additive from the ink is absent
Data Source
AI summary
Methods, inks, apparatus, and systems for forming metal features on semiconductor substrates are provided herein. Advantageously, the techniques herein do not require the use of photoresist, and can be accomplished without many of the processes and apparatuses used in the conventional process flow. Instead, electrohydrodynamic ejection printing is used to deposit an ink that includes an electroplating additive such as accelerator or inhibitor. The printed substrate can then be electroplated in a preferential deposition process that achieves a first deposition rate on areas of the substrate where the ink is present and a second deposition rate on areas of the substrate where the ink is absent, the first and second deposition rates being different from one another. After electroplating, chemical etching may be used to spatially isolate the preferentially grown metal features from one another.