Molybdenum Metal-on-Metal Deposition for Gap Fill Selectivity
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Solution Overview
Problem
Current semiconductor fabrication processes face challenges in filling gap features on non-planar substrates with metal films, particularly in achieving desired characteristics and selectivity, especially as device geometries shrink and high aspect ratio features become more common.
Innovation Solution
A cyclical deposition process using molybdenum metal-on-metal (MoM) selective bottom-up fill method, where molybdenum films are deposited only on metal surfaces within gap features, avoiding dielectric surfaces, with specific precursors and reactants like molybdenum chloride and hydrogen, and controlled temperature and pressure conditions to achieve selective growth up to several hundred angstroms thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional deposition methods (HDP, SACVD, LPCVD) are used for gap fill, then the process can be performed with standard equipment, but the desired gap fill capability and selectivity are not achieved
Solution Approach 1:
The invention changes the deposition parameters by using a cyclical deposition process with specific temperature ranges (200-450°C) and pressure conditions (5-100 Torr) to achieve selective molybdenum deposition on metal surfaces while preventing deposition on dielectric surfaces, thereby resolving the contradiction between gap fill capability and selectivity
Solution Approach 2:
The invention employs a cyclical deposition process where precursors and reactants are introduced in alternating cycles, allowing selective metal-on-metal deposition to occur during specific phases of the cycle, which enables both effective gap filling and high selectivity that conventional continuous deposition methods cannot achieve
2Reliability
If metal films are deposited to fill high aspect ratio gap features, then the electrical connectivity is improved, but seam formation and impurity incorporation increase
Solution Approach 1:
The metal-on-metal deposition process is self-selective, depositing molybdenum only on existing metal surfaces within the gap features while automatically avoiding dielectric surfaces, which eliminates seam formation at metal-dielectric interfaces and prevents impurity incorporation that would occur with conventional non-selective deposition methods
Solution Approach 2:
The deposition process exhibits local quality by being selective to specific surface types (metal vs. dielectric), depositing material only where needed (on metal surfaces) while leaving other areas unchanged (dielectric surfaces), thereby achieving complete gap filling without seams or impurities
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 effective filling of gap features with molybdenum films, achieving high selectivity and thickness, improving electrical properties and reducing seam formation, suitable for applications like 3D-NAND and CMOS logic, while maintaining low electrical resistivity and minimal impurities.
Implementation Method 1
Each cycle of the cyclical deposition process may include: (a) providing a molybdenum precursor in the reaction chamber; and (b) providing a reactant in the reaction chamber to form a layer of the molybdenum film
Data Source
AI summary
Molybdenum (Mo) metal-on-metal (MoM) deposition methods for providing true bottom-up fill in vias and/or other gap features in device structures. These device structures contain metal at the bottom surface and have dielectric sidewalls. The deposition process provides molybdenum growth only, in some cases, on the metal film/layer to provide a selective process that can be called a metal-on-metal (MoM) process. The Mo MoM deposition process described herein are not limited to thin films (e.g., films less than 50 Å) and can be used to deposit thicker films (e.g., greater than 50 Å in some cases and greater than 200 Å in other useful cases) on metal surfaces while no, or substantially no, deposition is found on dielectric surfaces.