Composite Insulator Films That Fill ALD Anneal Cracks
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Solution Overview
Problem
Existing capacitor fabrication techniques face challenges in achieving high capacitance and low electrical leakage, as high temperature anneals in atomic layer deposition (ALD) processes induce cracks and gaps in insulator films, leading to increased leakage currents.
Innovation Solution
A method involving alternating layer deposition (ALD) of a high-k insulator film followed by a thermal anneal, and then filling cracks with a less crystalline insulative material to form a composite insulator, which reduces electrical leakage while maintaining high capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal anneal is applied to achieve highly crystallized phase for high-k dielectric response, then dielectric constant is improved, but electrical leakage increases due to cracks and gaps in insulator films
Solution Approach 1:
The patent creates a composite insulator structure consisting of a first insulator material (high-k dielectric) and a second insulator material (filler material). The first material provides high dielectric constant, while the second material fills cracks and gaps to reduce electrical leakage. This composite approach allows both high capacitance and low leakage to be achieved simultaneously.
Solution Approach 2:
The patent converts the harmful effect of thermal annealing by using it to create a specific microstructure (hillocks and valleys) that can then be beneficially filled with a second insulator material. The thermal anneal-induced cracks, which normally increase leakage, are transformed into opportunities to embed leakage-blocking filler material.
2Productivity
If atomic layer deposition (ALD) is used to fill high aspect ratio structures, then capacitance density is improved, but manufacturing complexity increases due to high temperature anneal requirements
Solution Approach 1:
The patent divides the insulator formation process into separate steps: first depositing the high-k dielectric material, then separately filling the cracks with a second insulator material. This segmentation allows each material to be optimized independently and simplifies the overall fabrication process by avoiding the need for high temperature anneals.
Solution Approach 2:
The patent changes the deposition parameters by using ALD at lower temperatures without requiring high temperature anneals. This parameter change enables the formation of both the high-k dielectric and the filler material at temperatures compatible with standard semiconductor manufacturing processes.
3Ease of manufacture
If physical vapor deposition (PVD) is used to form thin films at low deposition temperatures, then manufacturing simplicity is improved, but ability to fill high aspect ratio structures is lost
Solution Approach 1:
The patent merges the advantages of both PVD and ALD approaches. The high-k dielectric is deposited using a simple process, and then ALD is used to fill the cracks with the second insulator material. This combination achieves both manufacturing simplicity and high capacitance density by filling high aspect ratio structures.
Solution Approach 2:
The patent performs preliminary deposition of the high-k dielectric material to create the hillock and valley microstructure, which is then subsequently filled with the second insulator material. This preliminary action enables the later filling step to achieve high capacitance density in high aspect ratio structures.
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 composite insulator film achieves significantly lower electrical leakage and higher dielectric constant compared to traditional methods, enhancing capacitor performance and reliability.
Implementation Method 1
atomic layer deposition (ALD) techniques are able to fill high aspect-ratio structures
Implementation Method 2
such processes often rely on high temperature anneals to achieve a film with a highly crystalized phase that is needed for the high-k dielectric (or charge storage) response
Implementation Method 3
insulator compositions of high relative permittivity and high dielectric response are attractive for capacitors offering high capacitance and low electrical leakage per unit area
Data Source
AI summary
Capacitor structures with a composite insulator comprising a first insulator and a second insulator. At least the first insulator is a compound of one or more metals and oxygen that may be deposited with an atomic layer deposition process upon topography having a high aspect ratio. Following a thermal anneal of the first insulator, the first insulator may be highly crystalline, but comprise a plurality of cracks where the first insulator is some lesser thickness. The second insulator may be deposited with an atomic layer deposition process to fill-in the cracks. Overburden associated with deposition of the second insulator may be removed and an electrode may then be formed over the resulting composite insulator.