# US 11,443,977 B2 · Silicon-on-insulator with crystalline silicon oxide

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- Number: US 11,443,977 B2
- Document ID: US11443977B2
- Status: Granted
- Kind: B2
- Application number: 16/611,413
- Filed: 2018-05-30
- Published: 2020-04-02
- Granted: 2022-09-13
- Earliest claimed: 2017-06-21
- Assignees: Turun Yliopisto
- Applicants: Turun yliopisto
- Inventors: Pekka Laukkanen; Mikhail Kuzmin; Jaakko Mäkelä; Marjukka Tuominen; Marko Punkkinen; Antti Lahti; Kalevi Kokko; Juha-Pekka Lehtiö
- Web page: https://patentgrep.com/patent/US11443977B2

## CPC

- H10P 90/1906: {Preparing SOI wafers}
- H10P 14/6309: {of silicon in uncombined form, i.e. pure silicon}
- H10P 14/6322: {Formation by thermal treatments (formation by plasma treatment H10P14/6319)}
- H10W 10/181: {Semiconductor-on-insulator [SOI] isolation regions, e.g. buried oxide regions of SOI wafers}
- H10W 74/137: {the encapsulations being directly on the semiconductor body (H10W74/134 takes precedence)}
- H10P 14/6334: {using decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition (deposition by physical ablation of a target H10P14/6329)}
- H10P 14/6339: {deposition by cyclic CVD, e.g. ALD, ALE or pulsed CVD}
- H10P 14/69215: {the material being a silicon oxide, e.g. SiO2}
- H10P 14/6938: {the material containing at least one metal element, e.g. metal oxides, metal oxynitrides or metal oxycarbides}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

A method (100) for forming a semiconductor structure (200) comprising a silicon-on-insulator layer structure with crystalline silicon oxide SiOx as the insulator material comprises: providing (120) a crystalline silicon substrate (201) having a substantially clean deposition surface (202) in a vacuum chamber; heating (130) the silicon substrate to an oxidation temperature To in the range of 550 to 1200, 550 to 1000, or 550 to 850° C.; supplying (140), while keeping the silicon substrate in the oxidation temperature, with an oxidation pressure Po in the range of 1·10−8 to 1·10−4 mbar in the vacuum chamber, molecular oxygen O2 into the vacuum chamber with an oxygen dose Do in the range of 0.1 to 1000 Langmuir; whereby a crystalline silicon oxide layer (204) with a thickness of at least two molecular layers is formed within the silicon substrate, between a crystalline silicon base layer (203) and a crystalline silicon top layer (205).

## Claims

### Claim 1

A method for forming a semiconductor structure comprising a silicon-on-insulator layer structure with crystalline silicon oxide SiOx as the insulator material, the method comprising:
providing a crystalline silicon substrate having a substantially clean deposition surface in a vacuum chamber;
heating the crystalline silicon substrate to an oxidation temperature To in the range of 550 to 1200° C.; and
supplying, while keeping the crystalline silicon substrate in the oxidation temperature, with an oxidation pressure Po in the range of 1·10−8 to 1·10−4 mbar in the vacuum chamber, molecular oxygen O2 into the vacuum chamber with an oxygen dose Do in the range of 0.1 to 1000 Langmuir (L);
whereby at least part of the molecular oxygen supplied into the vacuum chamber is adsorbed onto the deposition surface and diffuses into the crystalline silicon substrate, and a crystalline silicon oxide layer with a thickness of at least two molecular layers is formed within the crystalline silicon substrate, between a crystalline silicon base layer and a crystalline silicon top layer.

### Claim 2 (depends on 1)

A method as defined in claim 1, wherein the oxidation temperature To lies in the range of 550 to 750° C., the oxidation pressure Po lies in the range of 1·10−7 to 1·10−4 mbar, and the oxygen dose Do lies in the range of 5 to 300 L.

### Claim 3 (depends on 2)

A method as defined in claim 2, wherein the oxidation temperature, the oxidation pressure, and the oxygen dose lie within one of the following parameter spaces a) to f):
a) To=550 to 700° C., Po=1·10−7 to 1·10−4 mbar, Do=10 to 50 L;
b) To=650 to 700° C., Po=1·10−7 to 1·10−6 mbar, Do=50 to 100 L;
c) To=650 to 750° C., Po=1·10−7 to 5·10−7 mbar, Do=50 to 300 L;
d) To=700 to 750° C., Po=1·10−5 to 5·10−5 mbar, Do=5 to 50 L;
e) To=550 to 600° C., Po=1·10−6 to 5·10−7 mbar, Do=5 to 75 L;
f) To=700 to 750° C., Po=5·10−6 to 1·10−5 mbar, Do=10 to 100 L.

### Claim 4 (depends on 1)

A method as defined in claim 1, wherein the molecular oxygen is supplied into the vacuum chamber for an oxidation period of at least 0.5 s.

### Claim 5 (depends on 1)

A method as defined in claim 1, further comprising cleaning the deposition surface by removing possible native oxide and/or impurities on the deposition surface of the crystalline silicon substrate therefrom before supplying the molecular oxygen into the vacuum chamber.

### Claim 6 (depends on 1)

A method as specified in claim 1, wherein the deposition surface is a silicon {100}, silicon {111}, or silicon {110} surface.

### Claim 7 (depends on 1)

A method as specified in claim 1, further comprising annealing the crystalline silicon substrate, after supplying the molecular oxygen, at a post heating temperature in the range of 650 to 750° C. for 30 seconds to 60 minutes to remove possible excess oxygen not contained in the crystalline silicon oxide layer.

### Claim 8 (depends on 1)

A method as defined in claim 1, further comprising depositing a cap layer on the crystalline silicon top layer, the cap layer comprising, silicon dioxide SiO2, aluminum oxide Al2O3, hafnium oxide HfO2, or titanium oxide TiO2.

### Claim 9 (depends on 8)

A method as defined in claim 8, wherein the cap layer is deposited so as to have a thickness of 1 to 500 nm.

### Claim 10 (depends on 1)

A method as defined in claim 1, wherein the deposition surface is planar.

### Claim 11 (depends on 1)

A method as defined in claim 1, wherein the oxidation temperature To is in the range of 550 to 850° C.

### Claim 12

A semiconductor structure comprising a silicon-on-insulator layer structure with crystalline silicon oxide SiOx as the insulator material, comprising:
a crystalline silicon base layer;
a crystalline silicon oxide layer, with a thickness of at least two molecular layers, on the crystalline silicon base layer; and
a crystalline silicon top layer on the crystalline silicon oxide layer, wherein the semiconductor structure is formed by:
providing a crystalline silicon substrate have a substantially clean deposition surface in a vacuum chamber;
heating the crystalline silicon substrate to an oxidation temperature To in the range of 550 to 1200° C.; and
supplying, while keeping the crystalline silicon substrate in the oxidation temperature, with an oxidation pressure Po in the range of 1·10−8 to 1·10−4 mbar in the vacuum chamber, molecular oxygen O2 into the vacuum chamber with an oxygen dose Do in the range of 0.1 to 1000 Langmuir;
whereby at least part of the molecular oxygen supplied into the vacuum chamber is adsorbed onto the deposition surface and diffuses into the crystalline silicon substrate, and the crystalline silicon oxide layer is formed within the crystalline silicon substrate, between the crystalline silicon base layer and the crystalline silicon top layer.

### Claim 13 (depends on 12)

A semiconductor structure as defined in claim 12, wherein the deposition surface is silicon {100}, silicon {111}, or silicon {110}.