# US 8,541,283 B2 · High performance dielectric stack for DRAM capacitor

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- Number: US 8,541,283 B2
- Document ID: US8541283B2
- Status: Granted
- Kind: B2
- Application number: 13/830,282
- Filed: 2013-03-14
- Published: 2013-08-22
- Granted: 2013-09-24
- Earliest claimed: 2011-08-29
- Assignees: Intermolecular, Inc.; Elpida Memory, Inc.
- Applicants: Intermolecular, Inc.; Elpida Memory, Inc
- Inventors: Sandra G. Malhotra; Hanhong Chen; Wim Y. Deweerd; Mitsuhiro Horikawa; Kenichi Koyanagi; Hiroyuki Ode; Xiangxin Rui
- Web page: https://patentgrep.com/patent/US8541283B2

## CPC

- H10D 1/692: {Electrodes}
- H10D 1/68: Capacitors having no potential barriers
- H10D 1/696: {comprising multiple layers, e.g. comprising a barrier layer and a metal layer (barrier layers to prevent diffusion of hydrogen or oxygen in perovskite based capacitors H10D1/688)}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A method for fabricating a DRAM capacitor stack is described wherein the dielectric material is a multi-layer stack formed from a highly-doped material combined with a lightly or non-doped material. The highly-doped material remains amorphous with a crystalline content of less than 30% after an annealing step. The lightly or non-doped material becomes crystalline with a crystalline content of equal to or greater than 30% after an annealing step. The dielectric multi-layer stack maintains a high k-value while minimizing the leakage current and the EOT value.

## Claims

### Claim 1

A method for forming a capacitor stack, the method comprising:
forming a first electrode material above a substrate, wherein the first electrode material is a metal nitride;
forming a first ZrO2 material above the first electrode material, wherein the first ZrO2 material further contains a first dopant, wherein the first dopant is present at a concentration of less than 10 atomic %;
forming a second ZrO2 material above the first ZrO2 material, wherein the second ZrO2 material further contains a second dopant, wherein the second dopant is present at a concentration of greater than 15 atomic %;
forming a second electrode material on the second ZrO2 material, wherein the second electrode material is a metal nitride; and
annealing the capacitor stack, wherein the first ZrO2 material is equal to or greater than 30% crystalline after the annealing and the second ZrO2 material is less than 30% crystalline after the annealing.

### Claim 2 (depends on 1)

The method of claim 1, wherein the annealing occurs at a temperature between 400 C and 550 C.

### Claim 3 (depends on 1)

The method of claim 1, wherein the first electrode material comprises one of titanium nitride or tantalum nitride.

### Claim 4 (depends on 1)

The method of claim 1, wherein the first dopant comprises one of Al, Ge, Si, Ti, La, or combinations thereof.

### Claim 5 (depends on 4)

The method of claim 4, wherein the first dopant comprises Al.

### Claim 6 (depends on 1)

The method of claim 1, wherein the first ZrO2 material is non-doped.

### Claim 7 (depends on 1)

The method of claim 1, wherein the second dopant comprises one of Al, Ge, Si, Ti, La, or combinations thereof.

### Claim 8 (depends on 7)

The method of claim 7, wherein the second dopant comprises Al.

### Claim 9 (depends on 1)

The method of claim 1, wherein the first electrode material comprises titanium nitride, the first ZrO2 material is undoped, the second ZrO2 material is doped with 20% Al, and the second electrode material comprises titanium nitride.

### Claim 10 (depends on 9)

The method of claim 9, further comprising applying a treatment to the first electrode material before the forming of the first ZrO2 material.

### Claim 11

A method for forming a capacitor stack, the method comprising:
forming a first electrode material above a substrate, wherein the first electrode material is a metal nitride;
forming a first ZrO2 material above the first electrode material, wherein the first ZrO2 material further contains a first dopant, wherein the first dopant is present at a concentration of greater than 15 atomic %;
forming a second ZrO2 material above the first ZrO2 material, wherein the second ZrO2 material further contains a second dopant, wherein the second dopant is present at a concentration of less than 10 atomic %;
forming a second electrode material on the second ZrO2 material, wherein the second electrode material is a metal nitride; and
annealing the capacitor stack, wherein the first ZrO2 material is less than 30% crystalline after the annealing and the second ZrO2 material is equal to or greater than 30% crystalline after the annealing.

### Claim 12 (depends on 11)

The method of claim 11, wherein the annealing occurs at a temperature between 400 C and 550 C.

### Claim 13 (depends on 11)

The method of claim 11, wherein the first electrode material comprises one of titanium nitride or tantalum nitride.

### Claim 14 (depends on 11)

The method of claim 11, wherein the first dopant comprises one of Al, Ge, Si, Ti, La, or combinations thereof.

### Claim 15 (depends on 14)

The method of claim 14, wherein the first dopant comprises Al.

### Claim 16 (depends on 11)

The method of claim 11, wherein the second dopant comprises one of Al, Ge, Si, Ti, La, or combinations thereof.

### Claim 17 (depends on 16)

The method of claim 16, wherein the second dopant comprises Al.

### Claim 18 (depends on 11)

The method of claim 11, wherein the second ZrO2 material is non-doped.

### Claim 19 (depends on 11)

The method of claim 11, wherein the first electrode material comprises titanium nitride, the first ZrO2 material is doped with 20% Al, the second ZrO2 material is undoped, and the second electrode material comprises titanium nitride.

### Claim 20 (depends on 19)

The method of claim 19, further comprising applying a treatment to the first electrode material before the forming of the first ZrO2 material.