Capacitors with high energy storage density and low esr

Abstract

Electrostatic capacitors with high capacitance density and high-energy storage are implemented over conventional electrolytic capacitor anode substrates using highly conformal contact layers deposited by atomic layer deposition. Capacitor films that are suitable for energy storage, electrical and electronics circuits, and for integration onto PC boards endure long lifetime and high-temperature operation range.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS[0001]This application is a Divisional of U.S. patent application Ser. No. 11 / 658,201 filed on Jan. 19, 2007, which is a National Stage of PCT Application No. PCT / US2005 / 025768 filed on Jul. 20, 2005, which PCT application claims the benefit of U.S. Provisional Application No. 60 / 590,748 filed Jul. 23, 2004. All of the above patent applications, provisional, PCT, and non-provisional, are hereby incorporated by reference to the same extent as though fully contained herein.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]This invention relates to the area of electronic components and more specifically to apparatus and method for constructing capacitors with high capacitance and high-energy storage density as well as low equivalent series resistance.[0004]2. Description of Prior Art[0005]Capacitor devices have a host of applications in the electrical, electronics, and microelectronics arts. Many different useful implementations of ...

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Benefits of technology

[0017]However, ALD also provides robust and atomic-level control of film thickness and properties without the need for in-situ monitoring. It deposits continuous and uniform films on any three-dimensional surface structure, penetrating the most narrow and deep grooves, vias, and cavities. Accordingly, ALD films have unique pinhole free and low stress properties which may render them ideal candidates for high yield fabrication of high area devices.

[0021]ALD films can grow continuously at any thickness, provided that the surface of the substrate is made reactive to one of the ALD precursors. In this case, ALD films can be grown with layer-by-layer continuity all the way from the interface. The ability to initiate the surface and start layer-by-layer growth from the first layer makes ALD films continuous, low stress, and pinhole free; thus, it is an ideal candidate for devices with high-capacitance area substrates wherein the reliability and yield crucially depend on the number or density of defects. For example, ALD dielectric films are developed for DRAM capacitor applications wherein they were proven to maintain close to 100% yield for ultrathin films in the range of ˜5 nm over area-enhanced wafers with actual area exceeding 10,000 cm2. Additionally, Al2O3 dielectric films predominantly overtook PVD films in the magnetic data storage industry wherein magnetic sensors are manufactured at practically 100% yield using ALD. Finally, ALD films utilized for device encapsulation applications have shown significant device reliability improvements indicating pin-hole free coatings over large-size flat panel devices, as well as other devices. As a result, very thin encapsulation films can be realized by ALD with minimized adverse impact on device performance. For example, IC devices can be encapsulated at the wafer level with minimized impact on performance or subsequent packaging process flow.

[0023]It is the objective of the present invention to provide a method for capacitor manufacturing with improved capacitance and energy density while maintaining low ESR. It is another objective of the invention to improve electrolytic capacitor device layouts and create an electrostatic capacitor device layout by substituting the electrolyte with a highly conformal conductive film, therefore constructing an electrostatic capacitor while mainly implementing electrolytic capacitors manufacturing techniques. It is yet another objective of this invention to improve the temperature resilience and the lifetime of high-capacitance and high-energy density capacitors. It is also the objective of this invention to provide a capacitor device layout and related fabrication methods that are compatible with alternating current (AC). It is also an objective of this invention to provide capacitors that can be integrated into PC boards.

[0024]In another scope of the invention, capacitor manufacturing yield is improved by incorporating methods and apparatus for repairing defects within capacitor dielectric layers. In another aspect of the invention, capacitor manufacturing yield is further improved by incorporating “self-healing” of localized, low-dielectric, breakdown spots.

[0025]In another aspect of this invention, the equivalent series resistance (ESR) of high-capacitance and high-energy density capacitors is substantially reduced by substantially reducing the contact resistance with both the anode and the cathode.

[0026]The invention implements high-capacitance area anode substrates that are commonly used in the fabrication of electrolytic capacitors together with conformal formation of high-quality dielectric films and conductive films to fabricate electrostatic capacitors with substantially improved capacitance density, lifetime, and temperature endurance. Complimentarily, the invention teaches layouts and fabrication methods that achieve high-capacitance density and high-energy density capacitors with extremely low ESR. Additionally, the invention presents a viable scheme for capacitor-PCB integration.

Problems solved by technology

ALD, up to now, has been considered too slow a process to make the fifty-micron thick films generally associated with such applications.

Thus, to build up a fifty-micron film using this technique has been considered far too laborious and slow for commercial purposes.

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