Copper Plasma Etching with Low-Temperature Susceptor
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Solution Overview
Problem
Conventional wet-etching processes face difficulties in controlling precise critical dimensions for copper wires with widths of 2 micrometers or less, leading to challenges in forming high-resolution and high-density circuits in electronic devices, and often result in redeposition of etching by-products which can contaminate the substrate and reduce yield.
Innovation Solution
A copper plasma etching method using an electron cyclotron resonance (ECR) plasma source with hydrogen chloride and hydrogen gas, maintaining a susceptor temperature at 10° C. or less, and employing reactive ion etching to form CuH and Cu3Cl3 at room temperature, preventing redeposition and allowing precise control of critical dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wet-etching process is used for copper wire etching, then the etching process is simple and easy to implement, but the critical dimensions cannot be precisely controlled and by-products are redeposited on the substrate
Solution Approach 1:
The patent replaces the chemical wet-etching process with a plasma-based physical-chemical etching process. The plasma etching apparatus uses ion bombardment and reactive species to etch copper, providing precise control over etching rate and profile while preventing by-product redeposition through the plasma environment and controlled gas flow, thus resolving the contradiction between process simplicity and manufacturing precision.
Solution Approach 2:
The patent employs multiple parameter changes in the plasma etching process including controlling plasma power, gas pressure, gas composition (CHF3, CF4, O2), and substrate temperature to optimize etching performance. By adjusting these parameters, the process achieves precise critical dimension control while maintaining operational feasibility, resolving the contradiction between ease of manufacture and manufacturing precision.
2Ease of operation
If conventional plasma etching is used without temperature control, then the process is simpler to operate, but by-products are redeposited and process stability deteriorates
Solution Approach 1:
The patent implements a self-regulating temperature control system where the substrate temperature is actively monitored and controlled during plasma etching. The cooling system automatically maintains the substrate within the optimal temperature range, preventing by-product redeposition and ensuring process stability without requiring manual intervention, thus resolving the contradiction between ease of operation and reliability.
3Productivity
If additional energy sources such as heat or light are applied during copper etching, then the etching rate increases, but the process complexity and energy consumption increase
Solution Approach 1:
The patent utilizes the continuous energy input from plasma generation to drive the etching reaction at room temperature. The plasma provides sustained activation of reactive species that continuously etch the copper without requiring additional heating or lighting steps, maintaining high etching rates while avoiding the complexity and energy consumption associated with multiple energy input systems.
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 enables precise control of copper etching without additional energy sources, preventing by-product redeposition, improving process stability, and achieving high-density circuit formation with precise critical dimensions.
Implementation Method 1
plasma formed by an electron cyclotron resonance (ECR) plasma source
Implementation Method 2
plasma-etching the conductor layer that include copper on the substrate
Implementation Method 3
In the plasma-etching, reactive ion etching may be applied.
Implementation Method 4
maintaining a temperature of the susceptor at about 10° C. or less during the plasma-etching
Data Source
AI summary
A copper plasma etching method according an exemplary embodiment includes: placing a substrate on a susceptor in a process chamber of a plasma etching apparatus; supplying an etching gas that include hydrogen chloride into the process chamber; plasma-etching a conductor layer that include copper in the substrate; and maintaining a temperature of the susceptor at 10° C. or less during the plasma-etching.