Insulator Gap Filling via Sputter Redeposition for Void Elimination
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Solution Overview
Problem
Conventional integrated circuit fabrication methods lead to reductions in device yield and reliability due to voids in insulating layers and increased parasitic capacitive coupling, which can result in electrical shorts and decreased operating speeds.
Innovation Solution
The method involves depositing an electrically insulating layer with an undulating surface profile and using a sputter deposition technique to redistribute material from peaks to valleys, employing different plasma conditions for thickening and redeposition to create more uniform insulating layers, thereby addressing void formation and capacitive coupling issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conformal deposition of thick electrically insulating layers is performed on closely-spaced integrated circuit structures, then device integration level is increased, but voids form in the spaces between structures leading to electrical shorts
Solution Approach 1:
The patent applies local quality by performing selective redeposition only in the gap regions between integrated circuit structures. The insulating material is redistributed from peak areas to valley areas, creating locally thicker insulation precisely where needed to prevent shorts, while maintaining appropriate thickness elsewhere.
Solution Approach 2:
The patent changes the deposition parameters by switching from conformal deposition conditions to redeposition conditions. By adjusting plasma power, gas flow rates, and deposition temperature, the process transforms from uniform coating to targeted material redistribution, enabling void elimination without increasing overall layer thickness excessively.
2Reliability
If thinner insulating layers are used to prevent void formation, then electrical shorts are reduced, but parasitic capacitive coupling between adjacent structures increases lowering operating speeds
Solution Approach 1:
The patent achieves local quality by concentrating insulating material specifically in the gap regions between adjacent structures. This localized thickening reduces parasitic capacitive coupling in critical areas while maintaining overall layer thickness that prevents voids, thereby improving both reliability and operating speed.
Solution Approach 2:
The patent skips the intermediate step of uniformly increasing layer thickness across the entire substrate. Instead, it directly targets the problematic gap regions for material redistribution, rushing through the selective redeposition process to achieve precise local control over insulation thickness.
3Quantity of substance
If conventional deposition methods are used to increase device integration, then more structures can be packed on substrate, but surface profile uniformity deteriorates with peaks and valleys
Solution Approach 1:
The patent applies inversion by reversing the conventional approach: instead of attempting to deposit material uniformly onto a non-planar surface, it uses the existing undulating surface as a template and redistributes material from high points to low points. This inverted strategy transforms surface irregularities into opportunities for gap filling.
Solution Approach 2:
The patent enables self-service by using the insulating layer itself as the source material for redeposition. The undulating surface profile automatically guides material redistribution, with peaks serving as sources and valleys as destinations, eliminating the need for external planarization equipment.
4Manufacturing precision
If etch-back and planarization techniques are applied to improve surface uniformity, then peaks and valleys are reduced, but effectiveness is lost when layers are located very close to substrate surface
Solution Approach 1:
The patent replaces mechanical planarization techniques (etch-back, chemical mechanical polishing) with a vapor-phase redeposition process. This substitution allows material redistribution to occur in the vapor phase without requiring physical contact or complex mechanical systems, making the process effective even for layers close to the substrate surface.
Solution Approach 2:
The patent introduces plasma as an intermediary medium to facilitate material redistribution. The plasma enables transport of insulating material from peak to valley regions without requiring direct mechanical intervention, serving as a mediator that makes the process effective for near-surface layers where conventional mechanical methods fail.
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 enhances device yield and reliability by eliminating voids and reducing parasitic capacitive coupling, resulting in improved surface profiles and increased operating speeds of integrated circuit devices.
Implementation Method 1
A non-uniform thickening step is then performed. This non-uniform thickening step includes thickening a portion of the electrically insulating layer by redepositing portions of the electrically insulating layer from the least one peak to the at least one valley. This redeposition occurs using a sputter deposition technique that utilizes the electrically insulating layer as a sputter target.
Implementation Method 2
the depositing step includes depositing the electrically insulating layer onto the integrated circuit substrate using a plasma deposition process. In particular, the depositing step may include depositing a silicon nitride layer using a first plasma that receives an inert gas (e.g., argon gas), a nitrogen containing gas and a silicon containing gas (e.g., SiH4) as source gases.
Data Source
AI summary
Methods of forming integrated circuit devices include depositing an electrically insulating layer onto an integrated circuit substrate having integrated circuit structures thereon. This deposition step results in the formation of an electrically insulating layer having an undulating surface profile, which includes at least one peak and at least one valley adjacent to the at least one peak. A non-uniform thickening step is then performed. This non-uniform thickening step includes thickening a portion of the electrically insulating layer by redepositing portions of the electrically insulating layer from the least one peak to the at least one valley. This redeposition occurs using a sputter deposition technique that utilizes the electrically insulating layer as a sputter target.