Method of manufacturing a field effect semiconductor device having a stacked gate insulation film and a gate electrode

• US 7,229,882 B2
• Filed: 12/07/2004
• Issued: 06/12/2007
• Est. Priority Date: 09/13/1999
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Nakamura, Katsumi
• Primary Examiner(s): Cao; Phat X.
• Application Number:
  US11/004,838
• Publication Number:
  US 20050151188A1
• Time in Patent Office: 917 Days
• Field of Search: 438/259, 438/270, 257/329, 257/330, 257/332
• US Class Current: 438/259
• CPC Class Codes: H01L 21/02164 the material being a silicon oxide, e.g. SiO2
• CPC Class Codes: H01L 21/0217 the material being a silicon nitride not containing oxygen, e.g. SixNy or SixByNz H01L21/02126 and H01L21/0214 take precedence
• CPC Class Codes: H01L 21/022 the layer being a laminate, i.e. composed of sublayers, e.g. stacks of alternating high-k metal oxides adhesion layers or buffer layers H01L21/02304, H01L21/02362
• CPC Class Codes: H01L 21/02233 of the semiconductor substrate or a semiconductor layer
• CPC Class Codes: H01L 21/02255 formation by thermal treatment H01L21/02252 takes precedence; after treatment of an insulating film H01L21/3105 and subgroups
• CPC Class Codes: H01L 21/02271 deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition H01L21/02266 takes precedence
• CPC Class Codes: H01L 21/28185 with a treatment, e.g. annealing, after the formation of the gate insulator and before the formation of the definitive gate conductor
• CPC Class Codes: H01L 21/28194 by deposition, e.g. evaporation, ALD, CVD, sputtering, laser deposition H01L21/28202 takes precedence
• CPC Class Codes: H01L 21/28202 in a nitrogen-containing ambient, e.g. nitride deposition, growth, oxynitridation, NH3 nitridation, N2O oxidation, thermal nitridation, RTN, plasma nitridation, RPN
• CPC Class Codes: H01L 21/28211 in a gaseous ambient using an oxygen or a water vapour, e.g. RTO, possibly through a layer H01L21/28194 and H01L21/28202 take precedence
• CPC Class Codes: H01L 21/3144 on silicon
• CPC Class Codes: H01L 29/513 the variation being perpendicular to the channel plane
• CPC Class Codes: H01L 29/518 the insulating material containing nitrogen, e.g. nitride, oxynitride, nitrogen-doped material
• CPC Class Codes: H01L 29/66348 with a recessed gate
• CPC Class Codes: H01L 29/7397 and a gate structure lying on a slanted or vertical surface or formed in a groove, e.g. trench gate IGBT

Abstract

A semiconductor device of the present invention includes an MOSFET which has a stacked gate insulation film formed of at least two types of insulation films, that is, a thermal oxide film provided on a semiconductor substrate and a CVD oxide film provided nearer to a gate electrode than thermal oxide film. The stacked insulation film is provided so that the ratio of the thickness of the CVD oxide film to that of the entire stacked gate insulation film is at least 20%. By such a structure, the gate insulation film thickness is kept uniform. Further, nitrogen may be segregated at an interface between the thermal oxide film and a semiconductor substrate and an interface between the gate electrode and the CVD oxide film. Thus, the occurrence of interface states is prevented between the gate insulation film and the semiconductor substrate as well as between the gate insulation film and the gate electrode. As a result, a semiconductor device with improved gate insulation film and transistor characteristics of an MOSFET as well as a manufacturing method thereof are obtained.

Claims

1. A method of manufacturing a field effect type semiconductor device having a stacked gate insulation film and a gate electrode on a semiconductor layer, comprising:

a step of forming said stacked gate insulation film including the steps of

forming a thermal oxide film on the semiconductor layer by thermal oxidation, and

forming a CVD oxide film on said thermal oxide film by a CVD method,

said stacked gate insulation film having nitrogen segregated at an interface region between at least one of said thermal oxide film and said semiconductor layer, and said gate electrode and said CVD oxide film, wherein

a concentration of nitrogen along an entire length of the stacked gate insulation film, excluding the vicinity of both interface regions, is higher than the average concentration of nitrogen in the semiconductor layer or the gate electrode, and

a ratio of a thickness of said CVD oxide film to that of an entire stacked gate insulation film is at least 20%.

2. The method of manufacturing a semiconductor device according to claim 1, wherein

said CVD oxide film is formed in the step of forming said CVD oxide film so that the ratio of the thickness of the CVD oxide film to that of said entire stacked gate insulation film is at least 50%.

3. The method of manufacturing a semiconductor device according to claim 1, wherein

said step of forming said stacked gate insulation film includes the step of forming said thermal oxide film and then nitriding said thermal oxide film to segregate nitrogen near an interface between said thermal oxide film and said semiconductor layer.

4. The method of manufacturing a semiconductor device according to claim 1, wherein

said semiconductor layer is constituted by a semiconductor substrate provided a trench therein, and

said thermal oxide film is formed along a surface of the trench in the step of forming said thermal oxide film.

5. The A method of manufacturing a field effect type semiconductor device having a stacked gate insulation film and a gate electrode on a semiconductor layer, comprising:

a step of forming said stacked gate insulation film including the steps of

forming a thermal oxide film on the semiconductor layer by thermal oxidation, and

forming a CVD oxide film on said thermal oxide film by a CVD method,

said stacked gate insulation film having nitrogen segregated at an interface region between at least one of said thermal oxide film and said semiconductor layer, and said gate electrode and said CVD oxide film, wherein

a concentration of nitrogen along an entire length of the stacked gate insulation film, excluding the vicinity of both interface regions, is higher than the average concentration of nitrogen in the semiconductor layer or the gate electrode, and

said step of forming said stacked gate insulation film includes the step of forming said CVD oxide film and then nitriding said CVD oxide film to segregate nitrogen near an interface between said thermal oxide film and said semiconductor layer and an interface between said gate electrode and said CVD oxide film.

6. A method of manufacturing a field effect type semiconductor device having a stacked gate insulation film and a gate electrode on a semiconductor layer, comprising:

a step of forming said stacked gate insulation film including the steps of

forming a thermal oxide film on the semiconductor layer by thermal oxidation, and

forming a CVD oxide film on said thermal oxide film by a CVD method,

said stacked gate insulation film having nitrogen segregated at an interface region between at least one of said thermal oxide film and said semiconductor layer, and said gate electrode and said CVD oxide film, wherein

a concentration of nitrogen along an entire length of the stacked gate insulation film, excluding the vicinity of both interface regions, is higher than the average concentration of nitrogen in the semiconductor layer or the gate electrode, and

said step of forming said stacked gate insulation film includes the step of forming, after forming said CVD oxide film, a silicon nitride film on said CVD oxide film.

7. The method of manufacturing a semiconductor device according to claim 6, wherein

said step of forming said stacked gate insulation film further includes the step of forming, after forming said silicon nitride film, an oxide film by oxidating a surface of said silicon nitride film.

8. The method of manufacturing a semiconductor device according to claim 7, wherein

said step of forming said stacked gate insulation film includes the step of forming, after forming said thermal oxide film, a silicon nitride film on said thermal oxide film, or forming, after said step of oxidating the surface of said silicon nitride film, another CVD oxide film on said oxide film.

9. A method of manufacturing a field effect type semiconductor device having a stacked gate insulation film and a gate electrode on a semiconductor layer, comprising:

a step of forming said stacked gate insulation film including the steps of

forming a thermal oxide film on the semiconductor layer by thermal oxidation, and

forming a CVD oxide film on said thermal oxide film by a CVD method,

forming a silicon nitride film on at least one of said thermal oxide film or said CVD oxide film, and

oxidating the surface of said silicon nitride film, wherein

said silicon nitride film is formed on said CVD oxide film, and

subsequent to oxidating the surface of said silicon nitride film, forming another CVD oxide film on the silicon nitride film.