US-20260128235-A1 - CONSOLIDATED POWDER ALUMINUM ELECTROLYTIC CAPACITOR FOR SEMICONDUCTOR DEVICE

Abstract

A method of manufacturing an aluminum electrolytic capacitor for a semiconductor device may include consolidating aluminum powder into a porous pellet, sintering the porous pellet, etching the porous pellet to increase a surface area thereof, anodizing the porous pellet to form an aluminum oxide dielectric layer on the etched porous pellet, and providing a conductive polymer layer on the aluminum oxide dielectric layer. The aluminum electrolytic capacitor may be surface mounted or may be embedded in an interposer or a package substrate of the semiconductor device or in a circuit board.

Inventors

• Michael Randall

Assignees

• SARAS MICRO DEVICES, INC.

Dates

Publication Date

20260507

Application Date

20241107

Claims (20)

1. 1 . A method of manufacturing an aluminum electrolytic capacitor for a semiconductor device, the method comprising: consolidating aluminum powder into a porous pellet; sintering the porous pellet; etching the porous pellet to increase a surface area thereof; anodizing the porous pellet to form an aluminum oxide dielectric layer on the etched porous pellet; and providing a conductive polymer layer on the aluminum oxide dielectric layer.
2. 2 . The method of claim 1 , further comprising inserting a conductive lead into the porous pellet prior to said sintering.
3. 3 . The method of claim 2 , wherein said inserting the conductive lead is performed prior to said consolidating.
4. 4 . The method of claim 1 , further comprising providing a conductive carbonaceous layer on the conductive polymer layer.
5. 5 . The method of claim 4 , further comprising providing a metallization layer on the conductive carbonaceous layer.
6. 6 . The method of claim 1 , wherein the porous pellet has a packing factor of 15%-93%.
7. 7 . The method of claim 1 , further comprising mixing the aluminum powder with a binder prior to said consolidating.
8. 8 . The method of claim 1 , further comprising removing organic material from the porous pellet by thermal processing.
9. 9 . The method of claim 1 , wherein said sintering is performed in a reducing atmosphere to control oxidation of the aluminum.
10. 10 . The method of claim 1 , wherein said sintering is performed in a non-oxidizing atmosphere.
11. 11 . The method of claim 1 , wherein said sintering is performed with a maximum thermal processing temperature below a melting point of the aluminum powder.
12. 12 . The method of claim 1 , wherein said sintering is performed with a maximum thermal processing temperature of 280 ºC to 655 ºC.
13. 13 . The method of claim 1 , wherein said etching increases the surface area by a factor of at least 2.
14. 14 . The method of claim 13 , wherein said etching increases the surface area by a factor of at least 10.
15. 15 . The method of claim 1 , wherein said etching comprises electrochemical etching.
16. 16 . The method of claim 1 , wherein said etching comprises chemical etching.
17. 17 . The method of claim 1 , wherein said etching comprises a combination of electrochemical and chemical etching.
18. 18 . The method of claim 1 , wherein said providing the conductive polymer layer comprises dipping the etched porous pellet with the aluminum oxide dielectric layer into conductive polymer precursor.
19. 19 . A method of manufacturing an aluminum electrolytic capacitor for a semiconductor device, the method comprising: consolidating aluminum powder into a porous pellet; sintering the porous pellet; etching the porous pellet to increase a surface area thereof; anodizing the porous pellet to form an aluminum oxide dielectric layer on the etched porous pellet; providing a conductive polymer layer on the aluminum oxide dielectric layer to form the aluminum electrolytic capacitor having the etched porous pellet as an anode and having the conductive polymer layer as a cathode; and embedding the aluminum electrolytic capacitor in an interposer or a package substrate of the semiconductor device.
20. 20 . A method of manufacturing an aluminum electrolytic capacitor for a semiconductor device, the method comprising: consolidating aluminum powder into a porous pellet; sintering the porous pellet; etching the porous pellet to increase a surface area thereof; anodizing the porous pellet to form an aluminum oxide dielectric layer on the etched porous pellet; providing a conductive polymer layer on the aluminum oxide dielectric layer to form the aluminum electrolytic capacitor having the etched porous pellet as an anode and having the conductive polymer layer as a cathode; and embedding the aluminum electrolytic capacitor in a circuit board.

Description

BACKGROUND Current chip-type and/or embedded aluminum electrolytic (AE) conductive polymer (CP) capacitors utilize aluminum foil that has been etched in order to increase surface area, and thus active area A, and accordingly capacitance per unit volume C/Vol. and capacitance per unit weight or mass (C/g, (gram)). Multiple etched aluminum foil sub-elements (or leafs) may be used in a stacked configuration to further increase A, and thus C/Vol. as well as C/g. This has been successful in enabling capacitance as high as 220 μF in a 7343-20 case size (i.e., metric case size of 7.3 mm length x 4.3 mm width x 2.0 mm thickness) with 6.3 Vrated, or about 3,500 μF per cm3 in packaged device form. However, this type of design leaves a large amount of inactive volume, with the active portion of the capacitor estimated to be less than 15% by volume in the case of the 7343-20 metric 220 μF 6.3 Vrated capacitor. The conventional stacking approach has other issues as well. Accurate stacked construction of the delicate foil leafs is complicated in comparison to other capacitor manufacturing methods such as those used to produce pressed tantalum or niobium powder pellets, leading to extra expense as well as quality and yield challenges. Because of this, AE CP capacitors tend to be expensive, i.e., about a third more expensive than their associated tantalum CP (conductive polymer) analogs per unit capacitance, despite bulk aluminum being ≲1/70th the cost of bulk tantalum. Unfortunately, tantalum CP capacitors are not a suitable replacement for AE CP capacitors because of the higher resistivity of tantalum, resulting in higher equivalent series resistance (ESR) of the capacitor. Additionally, Ta at 16.65 g/cm3 is more than 6 times the density of Al (2.70 g/cm3), resulting in capacitor devices that are unnecessarily high in C/g. Thus, pressed tantalum and niobium powder pellets do not achieve as high of a surface area per unit mass as stacked AE capacitors, limiting active area A and thus C/g. BRIEF SUMMARY The present disclosure contemplates various devices and methods for overcoming drawbacks accompanying the related art. One aspect of the embodiments of the present disclosure is a method of manufacturing an aluminum electrolytic capacitor for a semiconductor device. The method may comprise consolidating aluminum powder into a porous pellet, sintering the porous pellet, etching the porous pellet to increase a surface area thereof, anodizing the porous pellet to form an aluminum oxide dielectric layer on the etched porous pellet, and providing a conductive polymer layer on the aluminum oxide dielectric layer. Another aspect of the embodiments of the present disclosure is a method of manufacturing an aluminum electrolytic capacitor for a semiconductor device. The method may comprise consolidating aluminum powder into a porous pellet, sintering the porous pellet, etching the porous pellet to increase a surface area thereof, anodizing the porous pellet to form an aluminum oxide dielectric layer on the etched porous pellet, providing a conductive polymer layer on the aluminum oxide dielectric layer to form the aluminum electrolytic capacitor having the etched porous pellet as an anode and having the conductive polymer layer as a cathode, and embedding the aluminum electrolytic capacitor in an interposer or a package substrate of the semiconductor device. Another aspect of the embodiments of the present disclosure is a method of manufacturing an aluminum electrolytic capacitor for a semiconductor device. The method may comprise consolidating aluminum powder into a porous pellet, sintering the porous pellet, etching the porous pellet to increase a surface area thereof, anodizing the porous pellet to form an aluminum oxide dielectric layer on the etched porous pellet, providing a conductive polymer layer on the aluminum oxide dielectric layer to form the aluminum electrolytic capacitor having the etched porous pellet as an anode and having the conductive polymer layer as a cathode, and embedding the aluminum electrolytic capacitor in a circuit board. The method of any of the above aspects may comprise inserting a conductive lead into the porous pellet prior to sintering, or attaching a conductive lead to the porous pellet after sintering by way of spot welding, laser welding or the like. The conductive lead may be inserted prior to consolidating the aluminum powder. The method may comprise providing a conductive carbonaceous layer on the conductive polymer layer. The method may comprise providing a metallization layer on the conductive carbonaceous layer. The porous pellet may have a packing factor of 15%-93%, preferably 25%-80%, more preferably 35%-60%. The method may comprise mixing the aluminum powder with a binder prior to consolidating the aluminum powder. The method may comprise removing organic material from the porous pellet by thermal processing. The sintering may be performed in a reducing sintering atmosphere to control o