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US-20260128236-A1 - ALUMINUM ELECTROLYTIC CAPACITOR FOR SEMICONDUCTOR DEVICE AND ARRAY PRODUCTION METHODS THEREOF

US20260128236A1US 20260128236 A1US20260128236 A1US 20260128236A1US-20260128236-A1

Abstract

The fabrication of conductive polymer aluminum dielectric capacitors proceeds with patterning an array of anode structures on a capacitor precursor laminate structure of a carrier and a metal layer adhered to the carrier. Substantially the entire thickness of the metal layer of each of the anode structures is etched, and an open accessible surface area of the metal layer is increased accordingly. The open accessible surface area of the anode structures is then anodized to form an oxide layer, thus defining anodes. Cathode counter-electrodes are established on each of the anodes. Input/output structures are attached to the anodes and to the cathode counter-electrodes. Given ones of the anodes, cathode counter-electrodes, and the input/output structures define a capacitor unit, and multiple ones of the capacitor unit may define a capacitor or a capacitor array.

Inventors

  • Michael Randall
  • Richard Sheridan
  • Ron Huemoeller

Assignees

  • SARAS MICRO DEVICES, INC.

Dates

Publication Date
20260507
Application Date
20241101

Claims (20)

  1. 1 . A method for fabricating capacitors for a semiconductor device, comprising: patterning an array of anode structures on a capacitor precursor laminate structure of a carrier and a metal layer adhered to the carrier; etching the metal layer throughout substantially an entirety of a thickness of each of the anode structures of the array, an open accessible surface area of the metal layer being increased; anodizing the open accessible surface area of the anode structures, an oxide layer being formed on the open accessible surface area of the metal layer to define anodes; establishing cathode counter-electrodes on each of the anodes; and attaching input/output structures to the anodes and to the cathode counter-electrodes; wherein given ones of the anodes, cathode counter-electrodes, and the input/output structures defining a capacitor unit, multiple ones of the capacitor unit defining a capacitor array.
  2. 2 . The method of claim 1 , wherein etching the metal layer of each of the anode structures of the array includes drilling holes of varying depths therein.
  3. 3 . The method of claim 1 , wherein establishing the cathode counter-electrodes on each of the anodes includes filling the open accessible surface area of the metal layer with a conductive polymer material.
  4. 4 . The method of claim 1 , further comprising stacking a plurality of capacitor arrays atop one another, a first one of the plurality of capacitor arrays being adhered to a second one of the plurality of capacitor arrays.
  5. 5 . The method of claim 1 , further comprising mating a first one of the plurality of capacitor arrays to a second one of the plurality of capacitor arrays.
  6. 6 . The method of claim 1 , further comprising removing the carrier layer from the metal layer.
  7. 7 . The method of claim 1 , further comprising singulating the capacitor units from the capacitor array.
  8. 8 . A method for fabricating capacitors for a semiconductor device: patterning an array of anode structures on a capacitor precursor laminate structure of a first carrier and an aluminum foil layer adhered to the first carrier, each of the anode structures being electrically interconnected and connected to a peripheral bus bar; machining a plurality of holes into the aluminum foil layer of each of the anode structures; etching the aluminum foil layer throughout substantially an entirety of its thickness to increase an open accessible surface area thereof while maintaining electrical conductivity; anodizing the aluminum foil layers of the anode structures to define an oxide layer within the open accessible surface area thereof and form anodes corresponding to the anode structures; filling the open accessible surface area of the anodes with a conductive polymer material to define cathode counter electrodes; applying a conductive carbon layer to the cathode counter electrodes, the conductive carbon layer extending at least partially across respective ones of the cathode counter electrodes and defining conductive carbon segments; applying a metallic conductor layer to the conductive carbon layer, the metallic conductor layer extending at least partially across respective ones of the conductive carbon layer and defining metallic conductor segments; and connecting the metallic conductor segments to respective ones of cathode lead frames.
  9. 9 . The method of claim 8 , further comprising: filling areas around the anode structures with an insulating material; wherein the conductive carbon layer extends across the insulating material.
  10. 10 . The method of claim 8 , further comprising removing the first carrier from the aluminum foil layer after filling the open accessible surface area of the anodes.
  11. 11 . The method of claim 8 , further comprising adhering a second carrier to a side opposite the first carrier.
  12. 12 . The method of claim 11 , further comprising: singulating capacitor units defined at least by given ones of the anodes, the cathode counter electrodes, the conductive carbon segments, the metallic conductor segments, and the cathode lead frames; and fixing an anode terminal to the anode of a given one of the capacitor units, and a cathode terminal to the cathode lead frame of the given one of the capacitor units.
  13. 13 . The method of claim 12 , further comprising: mating a first array of capacitor units to a second array of connected capacitor units, each of the capacitor units being defined at least by given ones of the anodes, the cathode counter electrodes, the conductive carbon segments, the metallic conductor segments, and the cathode lead frames, the first array of capacitor units being adhered to the second array of capacitor units; singulating pairs of the mated capacitor units; and fixing an anode terminal to the anode of a given one of the capacitor units, and a cathode terminal to the cathode lead frame of the given one of the capacitor units.
  14. 14 . A capacitor, comprising: an anode having an accessible open pore surface area greater than 1.6 m 2 /cm 3 ; and an anodized dielectric coating on the anode, an anodized accessible open pore surface area exceeding 1.5 m 2 /cm 3 .
  15. 15 . The capacitor of claim 14 , wherein capacitance exceeds 3,500 micro Farad per cubic centimeter.
  16. 16 . The capacitor of claim 14 , wherein the anode defines one or more holes.
  17. 17 . The capacitor of claim 16 , wherein one of the one or more holes is a through a hole extending from one exterior surface of the anode to another.
  18. 18 . The capacitor of claim 16 , wherein the one the one or more holes is a blind hole extending partially through the anode.
  19. 19 . The capacitor of claim 14 , further comprising a carrier to which the anode is adhered.
  20. 20 . The capacitor of claim 14 , wherein the anode is aluminum foil.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS Not Applicable STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT Not Applicable BACKGROUND 1. Technical Field The present disclosure relates generally to passive electronic devices and capacitors specifically, as well as fabrication methods thereof. The present disclosure relates more particularly to aluminum electrolytic capacitor array production methods and capacitors resulting therefrom. 2. Related Art Capacitors are an important part of many integrated and embedded circuits and are commonly used as energy storage structures, as primary components in filters and other signal conditioning applications, and as specific components of other types of complex integrated circuits. Capacitors are commonly arranged as a pair of opposing thin electrodes separated by a dielectric, with electrical energy being stored as a consequence of equal and opposite relative polarities on the opposing electrodes. A wide variety of configurations of capacitors are known in the art. One configuration is the aluminum electrolytic capacitor that utilizes aluminum foil as the electrodes with a thin oxide layer thereon serving as the dielectric. A solid conductive polymer is utilized as the electrolyte. Such solid conductive polymer aluminum electrolytic capacitors exhibit numerous desirable properties such as low equivalent series resistance (ESR), resulting in high ripple current capability, long service life, low profile possible through compact packages with high capacitance per unit volume (C/Vol.), and cost reductions. Development efforts are focused on improvements in reducing ESR and maximizing C/Vol., while lowering prices. Improvements in this regard have been realized through evolving features, but revolutionary opportunities for improvements may be possible due to limitations inherent to the basic design of solid conductive polymer aluminum electrolytic capacitors. In general, solid conductive polymer aluminum electrolytic capacitors are comprised of an aluminum foil anodized to form an aluminum oxide dielectric on the aluminum layer. This establishes the anode and the dielectric of the capacitor. The aluminum foil is typically etched to increase the surface area (A) prior to anodization, so that the active area per unit volume of the anodized film is also increased. The capacitance per unit volume C/Vol., which is given by: (ε0·εr·A)tVol. where ε0 is the dielectric permittivity of free space, or 8.854×10−12 F/m, εr is the relative dielectric constant, a.k.a, K (unitless), A is the active area of the dielectric that is under electric field, given in (m2), and t is the distance between the conductors that apply the electric field, or the dielectric thickness, given in (m). In order to further increase C/Vol. and to simplify production, both sides of the aluminum foil are typically etched and anodized. The etched and anodized foil is characterized by an active portion and an inactive portion, with the active portion/volume contributing to increase A while the inactive portion/volume does not. Thus, when maximizing C/Vol., the active portion should be maximized, while the inactive portion should be minimized. The etched and anodized foil is typically cut into small sizes or leaflets, which are then aligned, stacked, and electrically/mechanically attached to an anode lead structure for further processing. This step is difficult and costly because the leaflets are prone to damage during the stacking and attachment steps. Furthermore, an additional anodization step of the stacked anode leaflets is necessary to establish or re-establish the oxide dielectric before proceeding to the next step of the manufacturing process (e.g., newly cut foil would need an initial anodization to establish the oxide dielectric, while damaged dielectric may need additional anodization). The stacked foil structure of the conductive polymer aluminum electrolytic capacitor is generally comprised of a capacitor element portion and a packaging and lead structure portion, with the inactive portion making up a relatively high proportion of the overall device. Furthermore, even within the capacitor element portion, there is a relatively large inactive portion. Indeed, the total active portion of the conductive polymer aluminum electrolytic capacitor is minimal, accounting for less than ˜5% of the overall volume. Accordingly, there is a need in the art to increase the active portion, so as to yield increases in the capacitance per unit volume (C/Vol.), and effectuate other capacitor performance parameter improvements such as equivalent series resistance (ESR). BRIEF SUMMARY The embodiments of the present disclosure are directed to the manufacturing of conductive polymer aluminum electrolytic capacitors by laminating aluminum foil or geometrically formed aluminum sheet or foil onto a carrier material. The lamination may be temporary or permanent. The carrier material may be a polyimide, biaxially oriented polypr