Cryogenic Tungsten-Boron-Carbide Etch for Hardmask Selectivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current dry plasma etching processes exhibit low selectivity between hardmask layers and underlying metal layers, leading to damage of the metal structure and challenges in etching control, especially as technology nodes progress.
Innovation Solution
A method of selective cryogenic etching involving the supply of an etching gas mixture containing fluorine-containing and hydrogen-containing gases to a processing chamber, where the substrate is maintained at a cryogenic temperature and RF power is applied to form a plasma, allowing for selective etching of hardmask layers with a selectivity ratio greater than 10:1.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dry plasma etching processes are used, then etching can be performed, but selectivity between hardmask layer and metal layer is low causing damage to metal structure
Solution Approach 1:
The patent applies parameter changes by utilizing cryogenic temperatures to fundamentally alter the etching chemistry and physical states of materials involved. This temperature parameter change enables highly selective etching of the hardmask layer while protecting the underlying metal layer, achieving over 10:1 selectivity and preventing metal structure damage that occurs in conventional room temperature processes.
Solution Approach 2:
The patent exploits phase transitions by maintaining the substrate at cryogenic temperatures during the etching process. This temperature condition induces specific phase states in the hardmask and metal materials that enable selective removal of the hardmask while preserving the metal layer, thereby resolving the selectivity issue in conventional etching processes.
2Productivity
If aggressive halogen chemistries or oxidizing chemistries are used for etching, then etching can be performed, but contamination of nearby metal layer occurs
Solution Approach 1:
The patent changes the temperature parameter to cryogenic conditions, which fundamentally alters the chemical reactivity and selectivity of the etching process. This parameter change enables effective hardmask etching while preventing the contamination of adjacent metal layers that occurs with aggressive chemistries at room temperature.
Solution Approach 2:
The cryogenic temperature acts as an intermediary condition that mediates between the etching chemistry and the materials being processed. This intermediate temperature state allows the etching process to selectively remove hardmask material while preventing harmful interactions with the metal layer, thus avoiding contamination.
3Manufacturing precision
If conventional etching processes are used, then etching can be performed, but accurate control of etching stopping point and etch selectivity becomes challenging
Solution Approach 1:
The patent utilizes cryogenic temperature as a controlling parameter that inherently provides excellent etch stop control. The low temperature creates distinct reactivity differences between materials, allowing precise control of the etching stopping point without requiring complex process control systems, thereby achieving high manufacturing 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
The method achieves highly selective etching of hardmask layers relative to the substrate, reducing the risk of damage to underlying metal structures and improving etching control, while maintaining a reduced etch rate of the hardmask layer.
Implementation Method 1
applying radio frequency power (RF power) to excite the process gas into a plasma state. The RF power can be inductively coupled, or capacitively coupled, to the plasma. The plasma disassociates the gas mixture into ion species and/or radicals that interface with the substrate to perform the desired deposition or etch processes.
Implementation Method 2
The RF power can be inductively coupled, or capacitively coupled, to the plasma.
Implementation Method 3
maintaining the device substrate at a cryogenic temperature
Data Source
AI summary
A method of selectively etching a hardmask layer formed on a device substrate. The method includes supplying an etching gas mixture to a process region of a processing chamber, where a device substrate is disposed in the process region when the etching gas mixture is supplied to the process region, where the device substrate may include a substrate, at least one cavity formed in the substrate, and a hardmask layer formed over the at least one cavity and over the substrate. The method also includes providing radio frequency (rf) power to the etching gas mixture to form a plasma in the process region.