High Density Plasma Etchback for Advanced Metallization
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Solution Overview
Problem
The etchback process in physical vapor deposition (PVD) systems often causes dielectric damage and overhang growth due to high energetic ions and low plasma density, leading to reduced device yield and reliability, especially in advanced nodes with ultra-low k dielectric materials.
Innovation Solution
A high density plasma etchback process is implemented with increased DC power to the target above 8 kW, a magnetic field strength of at least 100 Gauss, and a reduced RF bias to the substrate, creating a magnetic cusp that increases ionization and confinement, thereby reducing ion energy and maintaining a high etch to deposition (E/D) ratio above 2, minimizing dielectric damage and overhang growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If low plasma density is used for etchback, then ion energy is high which improves etching capability, but dielectric damage increases
Solution Approach 1:
The patent changes the plasma density parameter from low to high, which fundamentally alters the ion characteristics. High plasma density provides sufficient ion flux for effective etching while the increased plasma shielding reduces ion energy, thereby eliminating dielectric damage without sacrificing etching capability.
2Object-affected harmful factors
If RF bias power is lowered to reduce dielectric damage, then ion energy decreases, but etch rate becomes unacceptable
Solution Approach 1:
The patent changes the controlling parameter from RF bias power to plasma density. By maintaining high plasma density, the system achieves high etch rates through increased ion flux rather than high ion energy. This allows for effective etching without requiring high RF bias power, thus avoiding dielectric damage while maintaining acceptable etch rates.
3Productivity
If high energetic ions are used for etchback, then etching effectiveness is improved, but overhang growth and dielectric damage occur
Solution Approach 1:
The patent changes the ion characteristics from high energy to high density. The high plasma density provides sufficient ion flux for effective etching, while the reduced ion energy (due to plasma shielding) prevents the resputtering that causes overhang growth and the excessive damage to dielectric materials.
4Manufacturing precision
If conventional etchback process is used, then barrier layer thickness is reduced, but device yield and reliability decrease due to dielectric damage
Solution Approach 1:
The patent changes the plasma density parameter to achieve effective barrier layer thickness reduction without the harmful side effects of conventional processes. High plasma density enables controlled etching that removes excess barrier material while the reduced ion energy prevents dielectric damage, thereby maintaining both manufacturing precision and device reliability.
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 reduces dielectric damage and overhang growth, maintaining a high E/D ratio for effective etching while preventing excessive deposition, thus enhancing device yield and reliability.
Implementation Method 1
Magnetic fields are used to increase a residence time of the electrons by causing the electrons to spiral through the plasma
Implementation Method 2
As a result, ionization levels of the plasma feed gas also increase
Implementation Method 3
A negative potential applied to a cathode attracts the ions towards a target
Implementation Method 4
Target atoms are dislodged from the surface of the target by direct momentum transfer
Implementation Method 5
A high density plasma etchback process is implemented with increased DC power to the target above 8 kW, a magnetic field strength of at least 100 Gauss
Implementation Method 6
creating a magnetic cusp that increases ionization and confinement, thereby reducing ion energy
Data Source
AI summary
A physical vapor deposition (PVD) system and method includes a chamber including a target and a pedestal supporting a substrate. A target bias device supplies DC power to the target during etching of the substrate. The DC power is greater than or equal to 8 kW. A magnetic field generating device, including electromagnetic coils and/or permanent magnets, creates a magnetic field in a chamber of the PVD system during etching of the substrate. A radio frequency (RF) bias device supplies an RF bias to the pedestal during etching of the substrate. The RF bias is less than or equal to 120V at a predetermined frequency. A magnetic field produced in the target is at least 100 Gauss inside of the target.