# US 2008/0187747 A1 · Dielectric Film and Method of Forming the Same

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- Number: US 2008/0187747 A1
- Document ID: US20080187747A1
- Status: Published application
- Kind: A1
- Application number: 11/883,421
- Filed: 2006-01-20
- Published: 2008-08-07
- Earliest claimed: 2005-02-01
- Assignees: Tohoku University
- Inventors: Tadahiro Ohmi; Akinobu Teramoto; Tetsuya Goto; Kazumasa Kawase
- Web page: https://patentgrep.com/patent/US20080187747A1

## CPC

- H10P 14/6526: {introduced into an oxide material, e.g. changing SiO to SiON}
- H10D 64/01344: {in a nitrogen-containing ambient, e.g. N2O oxidation}
- H10D 64/693: {the insulator comprising nitrogen, e.g. nitrides, oxynitrides or nitrogen-doped materials}
- H10P 14/6529: {by exposure to a gas or vapour}
- H10P 14/6532: {by exposure to a plasma}
- H10P 14/69433: {the material being a silicon nitride not containing oxygen, e.g. SixNy or SixByNz}
- H10P 14/6309: {of silicon in uncombined form, i.e. pure silicon}
- H10P 14/6927: {the material being a silicon oxynitride, e.g. SiON or SiON:H}
- Y10T 428/265: 1 mil or less
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A dielectric film wherein N in the state of an Si3=≡N bonding is present in a concentration of 3 atomic % or more in the surface side of an oxide film and also is present in a concentration of 0.1 atomic % or less in the interface side of the oxide film can achieve the prevention of the B diffusion and also the prevention of the deterioration of the NBTI resistance in combination. When the Ar/N2 radical nitridation is used, it is difficult for the resultant oxide film to satisfy the condition wherein N in the above bonding state is present in a concentration of 3 atomic % or more in the surface side of an oxide film and simultaneously is present in a concentration of 0.1 atomic % or less in the interface side of the oxide film, whereas, the above distribution of the N concentration can be achieved by using any of the gas combinations of Xe/N2, Kr/N2, Ar/NH3, Xe/NH3, Kr/NH3, Ar/N2/H2, Xe/N2/H2 and Kr/N2/H2.

## Claims

### Claim 1

A dielectric film formed on a silicon surface, wherein:
an N concentration at a surface of the dielectric film is 3 at % or more,
an N concentration present at an interface between the silicon surface and the dielectric film is 0.1 at % or less, and
a film thickness is 2 nm or less.

### Claim 2

A semiconductor device comprising a silicon substrate, a dielectric film formed on a surface of the silicon substrate, and an electrode formed on the dielectric film, wherein:
an N concentration at a surface of the dielectric film is 3 at % or more,
an N concentration present at an interface between the silicon surface and the dielectric film is 0.1 at % or less, and
a film thickness is 2 nm or less.

### Claim 3

A method of forming a dielectric film, comprising the steps of:
forming a silicon oxide film on a surface of a silicon substrate, and
altering a surface of the silicon oxide film by exposing the surface to a nitriding species such as a nitriding radical species, a nitriding excited active species, or a nitriding ion species.

### Claim 4 (depends on 3)

A method of forming a dielectric film according to claim 3, wherein:
the nitriding radical species is at least one radical selected from the group consisting of N radical, N+ ion radical, N2 radical, N2+ ion radical, NH radical, and NH+ ion radical.

### Claim 5 (depends on 3, 4)

A method of forming a dielectric film according to claim 3 or 4, wherein:
the nitriding radical is formed by a microwave plasma formed in a mixed gas of Ar and NH3, a mixed gas of Xe and N2, a mixed gas of Xe and NH3, a mixed gas of Kr and N2, a mixed gas of Kr and NH3, a mixed gas of Ar, N2, and H2, a mixed gas of Xe, N2, and H2, and a mixed gas of Kr, N2, and H2.

### Claim 6 (depends on 3, 4, 5)

A method of forming a dielectric film according to any one of claims 3 to 5, wherein:
the step of altering the surface of the silicon oxide film by exposing the surface to the nitriding species such as the nitriding radical species, the nitriding excited active species, or the nitriding ion species is not followed by post-annealing at 600° C. or more.

### Claim 7 (depends on 3, 4, 5, 6)

A method of forming a dielectric film according to any of claims 3 to 6, wherein:
the step of altering the surface of the silicon oxide film by exposing the surface to the nitriding species such as the nitriding radical species, the nitriding excited active species, or the nitriding ion species is performed at a temperature of 600° C. or less and followed by post-annealing in a vacuum or in an inert gas such as N2, Ar, Xe, or Kr at 500 to 600° C.

### Claim 8 (depends on 3, 4, 5, 6, 7)

A method of forming a dielectric film according to any of claims 3 to 7, wherein:
the step of altering the surface of the silicon oxide film by exposing the surface to the nitriding species such as the nitriding radical species, the nitriding excited active species, or the nitriding ion species is performed at a temperature of 600° C. or less and post-annealing in a vacuum or in an inert gas such as N2, Ar, Xe, or Kr at 500 to 600° C. is performed by way of pre-annealing for poly-Si film formation in a next step so as to reduce one post-annealing step.

### Claim 9

A method of manufacturing the semiconductor device, comprising the steps of:
forming a silicon oxide film on a surface of a silicon substrate,
altering a surface of the silicon oxide film by exposing the surface to a nitriding species such as a nitriding radical species, a nitriding excited active species, or a nitriding ion species, and
forming a gate electrode on the altered surface of the silicon oxide film.

### Claim 10 (depends on 9)

A method of manufacturing the semiconductor device according to claim 9, wherein:
the nitriding radical species is at least one radical selected from the group consisting of N radical, N+ ion radical, N2 radical, N2+ ion radical, NH radical, and NH+ ion radical.

### Claim 11 (depends on 9, 10)

A method of manufacturing the semiconductor device according to claim 9 or 10, wherein:
the nitriding radical is formed by a microwave plasma formed in a mixed gas of Ar and NH3, a mixed gas of Xe and N2, a mixed gas of Xe and NH3, a mixed gas of Kr and N2, a mixed gas of Kr and NH3, a mixed gas of Ar, N2, and H2, a mixed gas of Xe, N2, and H2, and a mixed gas of Kr, N2, and H2.

### Claim 12 (depends on 9, 10, 11)

A method of manufacturing the semiconductor device according to any one of claims 9 to 11, wherein:
the step of altering the surface of the silicon oxide film by exposing the surface to the nitriding species such as the nitriding radical species, the nitriding excited active species, or the nitriding ion species is performed at a temperature of 600° C. or less and is not followed by post-annealing at 600° C. or more.

### Claim 13 (depends on 9, 10, 11, 12)

A method of manufacturing the semiconductor device according to any one of claims 9 to 12, wherein:
the step of altering the surface of the silicon oxide film by exposing the surface to the nitriding species such as the nitriding radical species, the nitriding excited active species, or the nitriding ion species is performed at a temperature of 600° C. or less and followed by post-annealing in a vacuum or in an inert gas such as N2, Ar, Xe, or Kr at 500 to 600° C.

### Claim 14 (depends on 9, 10, 11, 12, 13)

A method of manufacturing the semiconductor device according to any one of claims 9 to 13, wherein:
the step of altering the surface of the silicon oxide film by exposing the surface to the nitriding species such as the nitriding radical species, the nitriding excited active species, or the nitriding ion species is performed at a temperature of 600° C. or less and post-annealing in a vacuum or in an inert gas such as N2, Ar, Xe, or Kr at 500 to 600° C. is performed by way of pre-annealing for poly-Si film formation in a next step so as to reduce one post-annealing step.

### Claim 15 (depends on 1)

A dielectric film according to claim 1, wherein:
a generation method of the plasma uses a microwave radiated from an RLSA (radial line slot antenna).

### Claim 16 (depends on 2)

A semiconductor device according to claim 2, wherein:
a generation method of the plasma uses a microwave radiated from an RLSA.

### Claim 17 (depends on 3, 4, 5, 6, 7, 8)

A method of forming a dielectric film according to any one of claims 3 to 8, wherein:
a generation method of the plasma uses a microwave radiated from an RLSA.

### Claim 18 (depends on 9, 10, 11, 12, 13, 14)

A method of manufacturing the semiconductor device according to any one of claims 9 to 14, wherein:
a generation method of the plasma uses a microwave radiated from an RLSA.