Sputtering Copper Seed Layers Without Titanium Barrier
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Solution Overview
Problem
Conventional substrate processing methods face challenges such as physical damage from high ion energy, material buildup from low ion energy, increased resistivity with titanium barrier layers, and stress induction with hard masks, which affect the integrity and performance of integrated circuits.
Innovation Solution
The method involves depositing a titanium barrier layer and a copper seed layer within substrate features using a process chamber with controlled DC and RF power, maintaining low pressure, and rotating a magnetron to enhance plasma density, thereby reducing stress and resistivity while improving step coverage and wetting properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high ion energy is used for redistribution, then material can be redistributed from bottoms to sidewalls, but physical damage occurs to underlying layers and substrate
Solution Approach 1:
The patent changes the energy parameter of ion bombardment from high energy to low energy range, and modifies the gas composition parameter by introducing oxygen-containing gas. This combination allows material redistribution to occur without causing physical damage to the substrate and underlying layers, resolving the contradiction between achieving good material distribution and avoiding substrate damage.
Solution Approach 2:
The patent introduces oxygen-containing gas into the sputtering chamber, creating an oxidizing environment during the deposition process. This oxidation modifies the material properties and enables redistribution at lower ion energies, preventing physical damage while still achieving the desired material distribution pattern on feature sidewalls.
2Object-affected harmful factors
If low ion energy is used for redistribution, then physical damage is avoided, but material builds up near openings causing overhang and void formation
Solution Approach 1:
The patent modifies two key parameters simultaneously: reduces ion energy to avoid damage and increases oxygen content in the process gas. The oxygen modification changes the material deposition characteristics, enabling atoms to migrate to sidewalls even at low energies, thus achieving good feature geometry without overhang or void formation.
Solution Approach 2:
The oxygen-containing gas acts as an intermediary that facilitates material redistribution. It creates a chemical environment that promotes atom migration and proper material distribution on feature sidewalls, enabling low-energy ion bombardment to achieve results normally requiring high energy, thereby avoiding both damage and geometry defects.
3Object-affected harmful factors
If titanium barrier layer is used to protect substrate, then physical protection is provided, but resistivity of integrated circuit increases
Solution Approach 1:
The patent removes the titanium barrier layer from the structure entirely. By using low-energy sputtering with oxygen-containing gas, the process achieves substrate protection and material redistribution without requiring the titanium layer, thereby eliminating the source of increased resistivity and thermodynamic inter-mixing problems.
Solution Approach 2:
The patent changes the deposition parameters (low ion energy, oxygen-containing atmosphere) to such an extent that the protective function previously requiring titanium is achieved directly through the deposition process itself. This parameter modification eliminates the need for the problematic barrier layer while maintaining substrate protection.
4Object-affected harmful factors
If hard mask such as titanium nitride is used as barrier layer, then substrate protection is provided, but stress is induced leading to device degradation
Solution Approach 1:
The patent eliminates the hard mask barrier layer by using low-energy sputtering with oxygen-containing gas. This extraction of the hard mask layer removes the source of stress induction while maintaining substrate protection through the modified deposition process, thereby preventing device degradation.
Solution Approach 2:
By changing the deposition parameters to low energy and oxygen-rich environment, the patent achieves a deposition mode that provides inherent substrate protection without requiring an additional hard mask layer. This parameter change eliminates the stress-related reliability issues associated with hard mask usage.
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 eliminates the need for additional protective layers, enhances feature opening size, reduces stress migration and electro-migration, and decreases resistivity, leading to improved substrate processing with better material distribution and reduced substrate damage.
Implementation Method 1
rotating a magnetron disposed proximate the target to form a magnetic field proximate the target to increase a density of the plasma proximate a surface of the target
Implementation Method 2
sputtering a material from a target in the presence of a plasma formed from a process gas
Implementation Method 3
sputtering a material from a target in the presence of a plasma formed from a process gas by applying a DC power to the target
Implementation Method 4
re-sputtering the material using high energy ions to facilitate redistribution
Implementation Method 5
providing up to about 5000 W of a substrate bias RF power to deposit a seed layer comprising the material atop the barrier layer
Data Source
AI summary
Methods for forming layers on a substrate are provided herein. In some embodiments, methods of forming layers on a substrate disposed in a process chamber may include depositing a barrier layer comprising titanium within one or more features in the substrate; and sputtering a material from a target in the presence of a plasma formed from a process gas by applying a DC power to the target, maintaining a pressure of less than about 500 mTorr within the process chamber, and providing up to about 5000 W of a substrate bias RF power to deposit a seed layer comprising the material atop the barrier layer.