Cyclic Metal Gap Fill for Reduced Feature Bending
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for depositing conducting materials like molybdenum to fill gaps between features on a substrate often cause feature bending, especially as feature aspect ratios increase and widths decrease, leading to device non-uniformity and reduced yield.
Innovation Solution
A cyclic deposition process involving a substrate with a nitrogen-containing reactant and a nucleation layer, such as molybdenum nitride, is used to form layers of molybdenum, tungsten, or ruthenium, which mitigates feature bending by forming transient surface species and improving film quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional deposition processes are used to deposit molybdenum to fill regions between features, then the gap fill application is achieved, but the features bend or warp during deposition
Solution Approach 1:
A nucleation layer is deposited beforehand on the substrate surface before the main molybdenum gap fill deposition. This preliminary layer modifies the surface properties and stress characteristics, preventing feature bending during subsequent deposition while maintaining effective gap fill capability
Solution Approach 2:
The deposition process parameters are changed by using a two-stage approach: first depositing a thin nucleation layer at controlled conditions, then continuing with the main gap fill deposition. This parameter change in the deposition sequence resolves the bending issue while preserving manufacturing capability
2Productivity
If the aspect ratio of features is increased to improve device density, then the device density is improved, but feature bending becomes increasingly problematic during deposition
Solution Approach 1:
The nucleation layer is deposited in advance on high aspect ratio features before the main gap fill material is deposited. This preliminary action prepares the surface to accommodate the deposition stress of high aspect ratio structures without bending, enabling continued device density improvement
Solution Approach 2:
The nucleation layer acts as a cushioning layer that absorbs or mitigates the stress that would otherwise cause bending in high aspect ratio features during deposition. This beforehand cushioning enables the use of higher aspect ratio features for improved density
3Length of moving object
If feature width is decreased to improve circuit scaling, then the circuit scaling is achieved, but feature bending during deposition becomes more severe
Solution Approach 1:
The nucleation layer is deposited beforehand on narrow features before the main gap fill deposition. This preliminary action modifies the surface properties of narrow features to resist bending during subsequent deposition, enabling continued circuit scaling to smaller feature widths
4Reliability
If molybdenum is used as the gap fill material to achieve desired electrical properties, then the effective resistivity is improved, but feature bending occurs during deposition
Solution Approach 1:
The gap fill deposition is segmented into two separate stages: first depositing a thin nucleation layer, then continuing with the main molybdenum gap fill. This segmentation allows the first stage to prepare the surface without causing bending, while the second stage achieves the desired electrical properties
Solution Approach 2:
The deposition parameters are changed by implementing a two-stage process with different deposition conditions. The first stage uses parameters optimized for nucleation layer formation that prevents bending, while the second stage continues with molybdenum deposition to achieve desired effective resistivity
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 significantly reduces feature bending, achieving less than 5% percentage feature bending, even in structures with high aspect ratios, thereby enhancing device uniformity and yield.
Implementation Method 1
using a cyclic deposition process, forming a layer comprising one or more of molybdenum, tungsten, and ruthenium; providing a nitrogen-containing reactant to the reaction chamber to form a transient surface species
Implementation Method 2
The cyclic deposition process can include providing a metal precursor comprising one or more of molybdenum, tungsten, and ruthenium to the reaction chamber and providing a reducing reactant to the reaction chamber
Data Source
AI summary
Methods for forming structures with reduced feature (e.g., line) bending are provided. Exemplary methods include using a cyclic deposition process, forming a layer comprising one or more of molybdenum, tungsten, and ruthenium, and providing a nitrogen-containing reactant to the reaction chamber to form a transient surface species. Use of the nitrogen-containing reactant is thought to mitigate metal interactions that are thought to contribute to feature bending.