CVD Showerhead with Multi-Zone Hole Control
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Solution Overview
Problem
In the fabrication of integrated circuits, the increase in substrate size and number of interconnect layers leads to poor step coverage and surface topography, resulting in unpredictable thickness variations after chemical-mechanical polishing (CMP), which complicates the formation of a planar surface and increases the out-of-control rate and rework in volume production.
Innovation Solution
A CVD apparatus with a showerhead having unevenly arranged holes to redistribute process gas, matching the deposition thickness profile to the CMP remove profile, ensuring that the deposited precursor material has a thickness that aligns with the subsequent CMP process, thereby improving the planarity of the formed dielectric or metal layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If substrate size is increased to process large wafers, then productivity is improved, but manufacturing precision deteriorates due to thickness variation
Solution Approach 1:
The showerhead is divided into multiple zones (first, second, and third zones) with different hole diameters. The first zone has smaller hole diameters, the second zone has intermediate hole diameters, and the third zone has larger hole diameters. This local variation in hole size creates different gas flow characteristics in different regions, enabling precise control of deposition thickness across the entire substrate surface while processing large wafers.
Solution Approach 2:
The showerhead structure is segmented into multiple functional zones with distinct hole diameter characteristics. This segmentation allows independent optimization of gas distribution in different regions, addressing the thickness uniformity problem across large substrates by treating different areas with appropriately sized holes.
2Manufacturing precision
If uniform film deposition is pursued, then manufacturing precision is improved, but device complexity increases due to multiple showerhead zones
Solution Approach 1:
Rather than using a single uniform showerhead design, the invention implements local quality by varying hole diameters in different zones. Each zone is optimized for its specific region, with smaller holes in the first zone for precise control, intermediate holes in the second zone for transition, and larger holes in the third zone for broader coverage, achieving uniform deposition without excessive complexity.
3Device complexity
If conventional gas distribution is used, then device complexity is kept low, but manufacturing precision deteriorates due to unpredictable thickness variation after CMP
Solution Approach 1:
The showerhead is designed with predetermined zone-specific hole diameters before the deposition process begins. This preliminary configuration of different hole sizes in different zones pre-establishes the gas flow patterns needed to compensate for subsequent CMP process variations, ensuring that the deposited film thickness profile matches the required specifications before CMP occurs.
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 the out-of-control rate by ensuring a more uniform deposition and polishing process, resulting in a planar surface with improved surface quality and reduced rework, as demonstrated by a comparison showing a decrease in out-of-control rate from 4-12% to mostly under 7%.
Implementation Method 1
chemical vapor deposition (CVD) is one of the important processes to form thin layers or films on a substrate. In the CVD process, the substrate is exposed to a precursor gas which reacts at the surface of the substrate and deposits a product of the reaction thereon
Data Source
AI summary
The present disclosure relates to a method of chemical vapor deposition (CVD). In some embodiments, a process gas is applied into a vacuum chamber. The process gas is guided downstream the vacuum chamber through a shower head arranged under the gas import, where the process gas is redirected to be laterally unevenly distributed under the shower head. A density of the process gas increases from a center region to a peripheral region of the vacuum chamber. The process gas is then deposited onto a first substrate to form a precursor material with an uneven thickness profile as a result of uneven distribution of the process gas. The shower head has multiple control zones each having a plurality of holes disposed through the shower head.