Flowable Dielectric Capping Layer for Wire Collapse Inhibition
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Solution Overview
Problem
Forming semiconductor features with high aspect ratio gaps poses challenges due to insulator material clogging, leading to voids and potential substrate cracking, especially as device geometries scale smaller.
Innovation Solution
A process involving a flowable film and a capping layer with compressive stress is used to fill gaps, where the flowable film is cured after forming the capping layer, counteracting tensile stress and preventing crack formation in the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If insulator material is used to fill high aspect ratio gaps, then gap filling is achieved, but voids form due to material clogging at the top of the gap
Solution Approach 1:
The patent changes the physical state and flow properties of the dielectric material by using a flowable dielectric with controlled viscosity that can navigate high aspect ratio gaps without clogging, then transforms it into a solid state through curing to achieve complete gap filling without voids
Solution Approach 2:
The patent utilizes phase transition of the dielectric material from a flowable liquid state during deposition to a solid cured state after treatment, enabling the material to flow into high aspect ratio gaps and then maintain structural integrity without forming voids
2Reliability
If flowable dielectric is used to fill narrow gap high aspect ratio patterns, then void formation is reduced, but substrate cracking occurs due to tensile stress during curing
Solution Approach 1:
The patent applies preliminary anti-action by forming a capping layer with compressive stress before curing the flowable dielectric, which counteracts the tensile stress that would otherwise cause substrate cracking during the curing process
Solution Approach 2:
The patent uses a capping layer with compressive stress as a counterweight to balance and neutralize the tensile stress generated during curing of the flowable dielectric, preventing substrate cracking while maintaining gap filling integrity
3Manufacturing precision
If curing treatment is applied to flowable dielectric, then chemical bonds are completed and dielectric constant is reduced, but wire flaking occurs due to outgassing
Solution Approach 1:
The patent provides beforehand cushioning by forming a capping layer over the wires before curing the flowable dielectric, which absorbs and contains the outgassing forces during curing, preventing wire flaking while allowing complete chemical bond formation
Solution Approach 2:
The patent introduces a capping layer as an intermediary between the flowable dielectric and the wires, which mediates the outgassing process during curing by containing the residual components and preventing them from causing wire flaking
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 achieves crack-free gap filling and inhibits wire flaking, ensuring structural integrity and preventing substrate cracking, even in high aspect ratio patterns.
Implementation Method 1
The flowable film is cured after forming the dielectric film. The curing increases tensile stress of the flowable film in the open area in the horizontal direction.
Implementation Method 2
The compressive stress of the dielectric film in the horizontal direction counteracts the tensile stress of the flowable film in the horizontal direction in the open area.
Data Source
AI summary
Techniques disclosed herein prevent wire flaking (collapse). One aspect is an improved way of forming wires over trenches, which may be located in a hookup region of a 3D memory array, and may be used to form electrical connections between conductive lines in the memory array and drivers. The trenches are formed between CMP dummy structures. The trenches are partially filled with a flowable oxide film, which leaves a gap in the trench that is at least as wide as the total pitch of the wires to be formed. A capping layer is formed over the flowable film. After forming a conductive layer over the dielectric layer, the conductive layer is etched to form conductive wires. Some of the capping layer, as well as the CMP dummy structures may be removed. Thus, the conductive wires may be at least temporarily supported by lines of material formed from the capping layer.