# US 8,772,050 B2 · Zr-substituted BaTiO3 films

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- Number: US 8,772,050 B2
- Document ID: US8772050B2
- Status: Granted
- Kind: B2
- Application number: 13/692,407
- Filed: 2012-12-03
- Published: 2013-05-16
- Granted: 2014-07-08
- Earliest claimed: 2006-08-03
- Assignees: Micron Technology, Inc.
- Applicants: Micron Technology, Inc.
- Inventors: Kie Y. Ahn; Leonard Forbes
- Web page: https://patentgrep.com/patent/US8772050B2

## CPC

- C23C 16/409: {of the type ABO3 with A representing alkali, alkaline earth metal or lead and B representing a refractory metal, nickel, scandium or a lanthanide}
- C23C 16/45529: {specially adapted for making a layer stack of alternating different compositions or gradient compositions}
- C23C 16/45531: {specially adapted for making ternary or higher compositions}
- H04L 12/4625: {Single bridge functionality, e.g. connection of two networks over a single bridge}
- H10D 30/60: Insulated-gate field-effect transistors [IGFET] (H10D30/40 takes precedence)
- H10D 64/01342: {by deposition, e.g. evaporation, ALD or laser deposition (H10D64/01344 takes precedence)}
- H10D 64/033: {comprising ferroelectric layers}
- H10D 64/685: {being perpendicular to the channel plane}
- H10D 64/689: {having ferroelectric layers}
- H10D 64/691: {comprising metallic compounds, e.g. metal oxides or metal silicates (insulators comprising nitrogen H10D64/693)}
- H10N 50/01: Manufacture or treatment
- H10P 14/6529: {by exposure to a gas or vapour}
- H10P 14/6339: {deposition by cyclic CVD, e.g. ALD, ALE or pulsed CVD}
- 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 14/69395: {the material containing zirconium, e.g. ZrO2}
- H10P 14/69397: {the material containing two or more metal elements}
- H10P 14/69398: {the material having a perovskite structure, e.g. BaTiO3}
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

The use of a monolayer or partial monolayer sequencing process, such as atomic layer deposition (ALD), to form a zirconium substituted layer of barium titanium oxide, produces a reliable ferroelectric structure for use in a variety of electronic devices such as a dielectric in nonvolatile random access memories (NVRAM), tunable dielectrics for multi layer ceramic capacitors (MLCC), infrared sensors and electro-optic modulators. In various embodiments, structures can be formed by depositing alternating layers of barium titanate and barium zirconate by ALD on a substrate surface using precursor chemicals, and repeating to form a sequentially deposited interleaved structure of desired thickness and composition. The properties of the dielectric may be tuned by adjusting the percentage of zirconium to titanium to optimize properties such as a dielectric constant, Curie point, film polarization, ferroelectric property and a desired relaxor response.

## Claims

### Claim 1

A method comprising:
forming a ferroelectric on a substrate by a monolayer or partial monolayer sequencing process, including:
forming a plurality of barium titanate monolayers on the substrate;
forming a plurality of barium zirconate monolayers on the substrate; and
repeating the forming of pluralities of barium titanate and barium zirconate monolayers on the substrate until a final thickness is obtained; and
annealing the ferroelectric at least once in one of a non-oxidizing ambient or an oxidizing ambient.

### Claim 2 (depends on 1)

The method of claim 1, further including forming an electrically conductive material on the ferroelectric.

### Claim 3 (depends on 2)

The method of claim 2, wherein the ferroelectric is a continuous layer having a root mean square surface roughness of less than 10 angstroms and a current leakage rate of less than 2×10−7 amps per cm2 at an electric field strength of 1 megavolt per cm.

### Claim 4 (depends on 2)

The method of claim 2, wherein the ferroelectric is separated from the substrate by a diffusion barrier.

### Claim 5 (depends on 2)

The method of claim 2, wherein the ferroelectric has a zirconium to titanium ratio of from 20% to 30%, and the film has the properties of a relaxor.

### Claim 6 (depends on 2)

The method of claim 2, wherein the ferroelectric is annealed at a temperature of 500° C. in air to form a substantially uniform single ferroelectric.

### Claim 7 (depends on 1)

The method of claim 1, wherein the barium titanate monolayer is formed by exposing an activated substrate surface at a preselected temperature to a first precursor material for a preselected time period and a preselected flow volume of the first precursor material to saturate the substrate surface with the first precursor material;
exposing the substrate surface to a preselected volume of a purge material for a preselected time period to remove substantially all of a non-adsorbed portion of the first precursor material from the substrate surface;
exposing the substrate surface to a preselected volume of a first reactant material for a preselected time period to react with the adsorbed portion of the first precursor material on the substrate surface to form barium titanate having a first intermediate thickness to complete a first deposition cycle;
exposing the substrate surface to a preselected volume of a purge material for a preselected time period to remove substantially all of a non-reacted portion of the first oxidizing reactant material, and a plurality of gaseous reaction byproducts from the substrate surface;
repeating the first deposition cycle until a preselected final dielectric material thickness is obtained for a first barium titanate region; and
wherein the barium zirconate monolayer is formed by exposing the substrate surface to a second precursor material for a preselected time period and a preselected flow volume of the second precursor material to saturate the substrate surface with the second precursor material;
exposing the substrate surface to a preselected volume of a purge material for a preselected time period to remove substantially all of a non-adsorbed portion of the second precursor material from the substrate surface;
exposing the substrate surface to a preselected volume of a second reactant material for a preselected time period to react with the adsorbed portion of the second precursor material on the substrate surface to form barium zirconate having a second intermediate thickness and completing a second deposition cycle; and
repeating the second deposition cycle until a preselected final first barium zirconate thickness is obtained.

### Claim 8 (depends on 7)

The method of claim 7, wherein the process of forming the final dielectric material thickness for the first barium titanate region and the final first barium zirconate film thickness is repeated to form multiple interleaved layers of barium titanate films and barium zirconate films having a final overall ferroelectric film thickness.

### Claim 9 (depends on 7)

The method of claim 7, wherein the first and second precursor materials and first and second reactant materials each comprise a combination of one or more materials selected from a list including barium bis(pentamethyl cyclopentadienyl), tetrakis (diethyl amino) zirconium, tetrakis (diethyl amino) titanium, zirconium tetrachloride, titanium tetrachloride, titanium tetraisoproxide, zirconium tetraisoproxide, zirconium tertiary-butoxide, titanium tertiary-butoxide, 2,2,6,6-tetramethyl-3,5-heptanedione titanium, 2,2,6,6-tetramethyl-3,5-heptanedione zirconium, water vapor, nitrous oxide, hydrogen peroxide, ozone, and oxygen.

### Claim 10 (depends on 7)

The method of claim 7, wherein the purge materials are all the same material and are selected from a list including chemically inert gases, nitrogen, neon, argon, hydrogen, and helium.

### Claim 11

A method comprising:
forming an integrated circuit having at least one device including a dielectric containing barium titanate and zirconium oxide, wherein forming the dielectric comprises:
forming a plurality of barium titanate monolayers on a substrate;
forming a plurality of barium zirconate monolayers on the substrate; and
repeating the forming of the pluralities of barium titanate and barium zirconate monolayers on the substrate until a final thickness is obtained;
annealing the dielectric to form a substantially single region of zirconium substituted barium titanate; and
forming a patterned conductive material coupled to the dielectric.

### Claim 12 (depends on 11)

The method of claim 11, wherein the method includes forming the patterned conductive material as at least one of an electrode of a capacitor, a gate electrode of a transistor, a gate electrode of a non-volatile memory cell, a tunnel gate device, an infrared sensor, or a part of a nanolaminate dielectric in a flash memory.

### Claim 13 (depends on 11)

The method of claim 11, wherein forming the patterned conductive material includes forming a conductive organic compound coupled to the dielectric.

### Claim 14 (depends on 11)

The method of claim 11, wherein the method includes forming the barium titanate and the zirconium oxide according to a selected titanium to zirconium ratio to obtain a selected level of an operation property of the such that the formed zirconium substituted barium titanate dielectric.

### Claim 15

A method comprising:
forming a memory array on a substrate including:
forming a ferroelectric containing zirconium substituted barium titanate in an integrated circuit by a monolayer or partial monolayer sequencing process that comprises:
forming a plurality of barium titanate monolayers on the substrate;
forming a plurality of barium zirconate monolayers on the substrate; and
repeating the forming of the pluralities of barium titanate and barium zirconate monolayers on the substrate until a final thickness is obtained;
annealing the ferroelectric at least once in one of a non-oxidizing ambient or an oxidizing ambient; and
depositing a conductive material contacting the ferroelectric; and
forming an address decoder in the substrate, the address decoder coupled to the memory array.

### Claim 16 (depends on 15)

The method of claim 15, wherein the method includes forming a non-volatile memory device.

### Claim 17 (depends on 15)

The method of claim 15, wherein the method includes forming a diffusion barrier layer inserted between the ferroelectric and the substrate, the composition of the diffusion selected to prevent metal contamination from affecting operational properties of a device in an integrated circuit.

### Claim 18

A method comprising:
providing a controller;
coupling an integrated circuit to the controller, wherein the integrated circuit includes a ferroelectric contacting a conductive material, wherein forming the ferroelectric contacting the conductive material includes:
forming the ferroelectric by a monolayer or partial monolayer sequencing process including:
forming a plurality of barium titanate monolayers on a substrate;
forming a plurality of barium zirconate monolayers on the substrate; and
repeating the forming of the pluralities of barium titanate and barium zirconate monolayers on the substrate until a final thickness is obtained;
annealing the ferroelectric at least once in one of a non-oxidizing ambient or an oxidizing ambient; and
depositing the conductive material such that the conductive material contacts the ferroelectric.

### Claim 19 (depends on 18)

The method of claim 18, wherein coupling an integrated circuit to the controller includes coupling a memory device formed as part of the integrated circuit.

### Claim 20 (depends on 18)

The method of claim 18, wherein forming the ferroelectric includes forming the ferroelectric in a charge storage device in the integrated circuit.