# US 5,352,622 A · Stacked capacitor with a thin film ceramic oxide layer

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- Number: US 5,352,622 A
- Document ID: US5352622A
- Status: Granted
- Kind: A
- Application number: 08/116,222
- Filed: 1993-09-02
- Granted: 1994-10-04
- Earliest claimed: 1992-04-08
- Assignees: National Semiconductor Corporation
- Inventors: Henry W. Chung
- Web page: https://patentgrep.com/patent/US5352622A

## CPC

- H10B 53/00: Ferroelectric RAM [FeRAM] devices comprising ferroelectric memory capacitors
- H10B 12/03: {Making the capacitor or connections thereto}
- H10D 1/68: Capacitors having no potential barriers
- H10B: ELECTRONIC MEMORY DEVICES
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A self-aligned thin-film ceramic oxide stacked capacitor on an underlying semiconductor substrate using a spin-on ceramic oxide fabricated by forming conductive pillars and the lower electrode, forming a temporary layer, building up the semiconductor substrate around the temporary layer, removing the temporary layer, and then spinning on the ceramic oxide. This results in a ceramic oxide stacked capacitor with the conformal thin-film ceramic oxide encapsulated by the top electrode.

## Claims

### Claim 1

A method of fabricating a thin-film ceramic oxide stacked capacitor on an underlying semiconductor substrate, the method comprising the steps of:
forming a layer of insulating material on the semiconductor substrate;
forming an opening in the layer of insulating material to expose a surface region of the semiconductor substrate;
forming a pillar of an electrically conductive material within the opening such that a bottom surface of the pillar is in electrical contact with the surface region of the semiconductor substrate and an exposed sidewall surface of the pillar extends above a top surface of the layer of insulating material, the pillar having a top portion of a lower electrode formed thereon;
forming a side portion of the lower electrode on the exposed sidewall surface of the pillar;
forming a temporary layer on a surface of the lower electrode;
forming a layer of molding material around the temporary layer;
removing the temporary layer so that an insulating mold is formed for a subsequent thin-film layer of ceramic oxide;
forming the thin-film layer of ceramic oxide on the lower electrode and in the mold;
forming an upper electrode on the thin-film layer of ceramic oxide, whereby the upper electrode functions as one plate of the thin-film ceramic oxide stacked capacitor, the thin-film layer of ceramic oxide functions as a dielectric, and the lower electrode functions as the other plate of the thin-film ceramic oxide stacked capacitor.

### Claim 2 (depends on 1)

The method of claim 1 wherein the insulating material comprises silicon oxide.

### Claim 3 (depends on 2)

The method of claim 2 wherein the molding material comprises silicon oxide.

### Claim 4 (depends on 3)

The method of claim 3 wherein the electrically conductive material comprises tungsten.

### Claim 5 (depends on 4)

The method of claim 4 wherein the ceramic oxide material comprises PLZT.

### Claim 6

A method of fabricating a thin-film ceramic oxide stacked capacitor on an underlying semiconductor substrate, the method comprising the steps of:
forming a layer of insulating material on a surface of the substrate;
forming an opening in the layer of insulating material to expose a surface region of the substrate;
depositing a first layer of electrically conductive material over a surface of the layer of insulating material so that the first layer of electrically conductive material fills the opening in the layer of insulating material;
depositing a second layer of electrically conductive material on the first layer of electrically conductive material;
etching the first and second layers of electrically conductive material to form an electrically conductive pillar so that a bottom surface of the pillar is in electrical contact with the surface region of the substrate and an exposed sidewall surface of the pillar extends above a top surface of the layer of insulating material, the pillar having a top portion of a lower electrode formed thereon;
depositing a third layer of electrically conductive material on the exposed sidewall surface of the electrically conductive pillar, the top portion of the lower electrode, and the layer of insulating material;
etching the third layer of electrically conductive material to form the lower electrode;
forming a layer of temporary material on a surface of the lower electrode;
forming a layer of an insulating molding material on a surface of the layer of temporary material and the layer of insulating material;
etching the layer of temporary material until the layer of temporary material is completely removed so that a trench is formed between the lower electrode and the layer of molding material;
forming a layer of ceramic oxide on a surface of the lower electrode and a surface of the layer of molding material so that the layer of ceramic oxide fills the trench created by the removal of the layer of temporary material;
removing the layer of molding material to form a thin-film layer of ceramic oxide having a substantially uniform thickness over the surface of the lower electrode and in the mold;
depositing a fourth layer of electrically conductive material on a surface of the thin-film layer of ceramic oxide and the layer of insulating material; and
etching the fourth layer of electrically conductive material to form the upper electrode so that the fourth layer of electrically conductive material encapsulates the thin-film layer of ceramic oxide.

### Claim 7 (depends on 6)

The method of claim 6 wherein the insulating material comprises silicon oxide.

### Claim 8 (depends on 7)

The process of claim 7 wherein the first layer of electrically conductive material comprises tungsten.

### Claim 9 (depends on 8)

The process of claim 8 wherein the second layer of electrically conductive material comprises ruthenium.

### Claim 10 (depends on 9)

The process of claim 9 wherein the third layer of electrically conductive material comprises ruthenium.

### Claim 11 (depends on 10)

The method of claim 10 wherein the molding material comprises silicon oxide.

### Claim 12 (depends on 11)

The process of claim 11 wherein the fourth layer of electrically conductive material comprises ruthenium.

### Claim 13 (depends on 12)

The process of claim 12 wherein the layer of insulating material comprises silicon oxide.

### Claim 14 (depends on 13)

The process of claim 13 wherein the layer of ceramic oxide comprises PLZT.

### Claim 15 (depends on 14)

The process of claim 14 wherein the layer of first material comprises tungsten.

### Claim 16 (depends on 15)

The process of claim 15 wherein the layer of second material comprises silicon oxide.