# US 11,309,383 B1 · Quad-layer high-k for metal-insulator-metal capacitors

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- Number: US 11,309,383 B1
- Document ID: US11309383B1
- Status: Granted
- Kind: B1
- Application number: 17/122,004
- Filed: 2020-12-15
- Granted: 2022-04-19
- Earliest claimed: 2020-12-15
- Assignees: International Business Machines Corporation
- Applicants: International Business Machines Corporation
- Inventors: Kisik Choi; Takashi Ando; Paul Charles Jamison; John Greg Massey; Eduard Albert Cartier
- Web page: https://patentgrep.com/patent/US11309383B1

## CPC

- H10D 1/042: {using deposition processes to form electrode extensions}
- H10D 1/68: Capacitors having no potential barriers
- H10D 1/692: {Electrodes}
- H10D 1/716: {having vertical extensions}
- H10P 14/662: {Laminate layers, e.g. stacks of alternating high-k metal oxides (adhesion layers or buffer layers H10P14/6508, H10P14/6548)}
- H10P 14/69391: {the material containing aluminium, e.g. Al2O3}
- H10P 14/69392: {the material containing hafnium, e.g. HfO2}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A semiconductor structure, and a method of making the same includes a multiple electrode stacked capacitor containing a sequence of first metal layers interleaved with second metal layers. A quad-layer stack separates each of the first metal layers from each of the second metal layers, the quad-layer dielectric stack includes a first dielectric layer made of Al2O3, a second dielectric layer made of HfO2, a third dielectric layer made of Al2O3, and a fourth dielectric layer made of HfO2.

## Claims

### Claim 1

A method of forming a semiconductor structure, the method comprising:
forming a multiple electrode stacked capacitor including a sequence of first metal layers interleaved with second metal layers, and separating each of the first metal layers from each of the second metal layers with a quad-layer stack; and
forming the quad-layer dielectric stack using:
a first dielectric layer comprising Al2O3,
a second dielectric layer comprising HfO2,
a third dielectric layer comprising Al2O3, and
a fourth dielectric layer comprising HfO2.

### Claim 2 (depends on 1)

The method of claim 1, wherein the sequence of first metal layers interleaved with the second metal layers comprises two or more of the first metal layers and two or more of the second metal layers.

### Claim 3 (depends on 1)

The method of claim 1, wherein the second dielectric layer comprising HfO2 is directly above the first dielectric layer comprising Al2O3, the third dielectric layer comprising Al2O3 is directly above the second dielectric layer comprising HfO2, and the fourth dielectric layer comprising HfO2 is directly above the third dielectric layer comprising Al2O3.

### Claim 4 (depends on 1)

The method of claim 1, wherein the first dielectric layer of the quad-layer dielectric stack passivates an interface between each of the first metal layers and the above HfO2/Al2O3/HfO2 stack formed by the second dielectric layer, the third dielectric layer, and the fourth dielectric layer.

### Claim 5 (depends on 1)

The method of claim 1, further comprising:
forming a fifth dielectric layer comprising Al2O3 above the fourth dielectric layer comprising HfO2, wherein a thickness of the fifth dielectric layer is equal to a thickness of the first dielectric layer, the fifth dielectric layer passivates an interface between each of the second metal layers and the HfO2/Al2O3/HfO2/Al2O3 stack below formed by the forth dielectric layer, the third dielectric layer, the second dielectric layer, and the first dielectric layer.

### Claim 6

A method of forming a semiconductor structure, the method comprising:
forming a first metal layer;
forming a first quad-layer dielectric stack on a surface of the first metal layer;
forming a second metal layer on a surface of the first quad-layer dielectric stack;
forming a second quad-layer dielectric stack disposed on a surface of the second metal layer; and
forming a third metal layer disposed on a surface of the second quad-layer dielectric stack, wherein each of the first quad-layer dielectric stack and the second quad-layer dielectric stack comprises:
a first dielectric layer comprising Al2O3,
a second dielectric layer comprising HfO2,
a third dielectric layer comprising Al2O3, and
a fourth dielectric layer comprising HfO2.

### Claim 7 (depends on 1)

The method of claim 1, wherein the first metal layer, the first quad-layer dielectric stack, and the second metal layer define a first capacitor comprising a first electrical bias polarity.

### Claim 8 (depends on 7)

The method of claim 7, wherein the second metal layer, the second quad-layer dielectric stack, and the third metal layer define a second capacitor comprising a second electrical bias polarity, the second electrical bias polarity being opposite to the first electrical bias polarity.

### Claim 9 (depends on 8)

The method of claim 8, wherein a dielectric break-down behavior is symmetric for both of the first electrical bias polarity and the second electrical bias polarity.

### Claim 10 (depends on 1)

The method of claim 1, wherein the second dielectric layer comprising HfO2 is directly above the first dielectric layer comprising Al2O3, the third dielectric layer comprising Al2O3 is directly above the second dielectric layer comprising HfO2, and the fourth dielectric layer comprising HfO2 is directly above the third dielectric layer comprising Al2O3.

### Claim 11 (depends on 6)

The method of claim 6, wherein the first dielectric layer of the first quad-layer dielectric stack is formed directly above the first metal layer to passivate a first interface between the first metal layer and the above HfO2/Al2O3/HfO2 stack formed by the second dielectric layer, the third dielectric layer, and the fourth dielectric layer of the first quad-layer dielectric stack.

### Claim 12 (depends on 6)

The method of claim 6, wherein the first dielectric layer of the second quad-layer dielectric stack is formed directly above the second metal layer to passivate a second interface between the second metal layer and the above HfO2/Al2O3/HfO2 stack formed by the second dielectric layer, the third dielectric layer, and the fourth dielectric layer of the second quad-layer dielectric stack.

### Claim 13 (depends on 6)

The method of claim 6, wherein a thickness of the first dielectric layer is less than 4 Å.

### Claim 14 (depends on 6)

The method of claim 6, further comprising:
forming a sequence of metal layers, wherein each pair of metal layers in the sequence of metal layers is separated by a quad-layer dielectric stack comprising the first dielectric layer, the second dielectric layer, the third dielectric layer, and the fourth dielectric layer.

### Claim 15 (depends on 6)

The method of claim 6, further comprising:
forming a fifth dielectric layer comprising Al2O3 above the fourth dielectric layer comprising HfO2, wherein a thickness of the fifth dielectric layer is equal to the thickness of the first dielectric layer, the fifth dielectric layer passivates an interface between each of the second metal layer and the third metal layer and the HfO2/Al2O3/HfO2/Al2O3 stack below formed by the forth dielectric layer, the third dielectric layer, the second dielectric layer, and the first dielectric layer.

### Claim 16

A semiconductor structure comprising:
a first metal layer;
a first quad-layer dielectric stack disposed on a surface of the first metal layer;
a second metal layer disposed on a surface of the first quad-layer dielectric stack;
a second quad-layer dielectric stack disposed on a surface of the second metal layer; and
a third metal layer disposed on a surface of the second quad-layer dielectric stack, wherein each of the first quad-layer dielectric stack and the second quad-layer dielectric stack comprises:
a first dielectric layer comprising Al2O3,
a second dielectric layer comprising HfO2,
a third dielectric layer comprising Al2O3, and
a fourth dielectric layer comprising HfO2.

### Claim 17 (depends on 16)

The semiconductor structure of claim 16, wherein the first metal layer, the first quad-layer dielectric stack, and the second metal layer define a first capacitor comprising a first electrical bias polarity.

### Claim 18 (depends on 17)

The semiconductor structure of claim 17, wherein the second metal layer, the second quad-layer dielectric stack, and the third metal layer define a second capacitor comprising a second electrical bias polarity, the second electrical bias polarity opposite the first electrical bias polarity.

### Claim 19 (depends on 18)

The semiconductor structure of claim 18, wherein a dielectric break-down behavior is symmetric for both of the first electrical bias polarity and the second electrical bias polarity.

### Claim 20 (depends on 16)

The semiconductor structure of claim 16, wherein the second dielectric layer comprising HfO2 is directly above the first dielectric layer comprising Al2O3, the third dielectric layer comprising Al2O3 is directly above the second dielectric layer comprising HfO2, and the fourth dielectric layer comprising HfO2 is directly above the third dielectric layer comprising Al2O3.

### Claim 21 (depends on 16)

The semiconductor structure of claim 16, wherein the first dielectric layer of the first quad-layer dielectric stack is positioned directly above the first metal layer to passivate a first interface between the first metal layer and the above HfO2/Al2O3/HfO2 stack formed by the second dielectric layer, the third dielectric layer, and the fourth dielectric layer of the first quad-layer dielectric stack.

### Claim 22 (depends on 16)

The semiconductor structure of claim 16, wherein the first dielectric layer of the second quad-layer dielectric stack is positioned directly above the first metal layer to passivate a second interface between the second metal layer and the above HfO2/Al2O3/HfO2 stack formed by the second dielectric layer, the third dielectric layer, and the fourth dielectric layer of the second quad-layer dielectric stack.

### Claim 23 (depends on 16)

The semiconductor structure of claim 16, wherein a thickness of the first dielectric layer is less than 4 Å.

### Claim 24 (depends on 16)

The semiconductor structure of claim 16, further comprising:
a sequence of metal layers, wherein each pair of metal layers in the sequence of metal layers is separated by a quad-layer dielectric stack comprising the first dielectric layer, the second dielectric layer, the third dielectric layer, and the fourth dielectric layer.

### Claim 25 (depends on 16)

The semiconductor structure of claim 16, further comprising:
a fifth dielectric layer comprising Al2O3 directly above the fourth dielectric layer comprising HfO2, wherein a thickness of the fifth dielectric layer is equal to the thickness of the first dielectric layer, the fifth dielectric layer passivates an interface between each of the second metal layer and the third metal layer and the HfO2/Al2O3/HfO2/Al2O3 stack below formed by the fourth dielectric layer, the third dielectric layer, the second dielectric layer, and the first dielectric layer.