Method for manufacturing a semiconductor device

Abstract

Embodiments of the present application provide a method for manufacturing a semiconductor device, in which a semiconductor layer is oxidized at a low temperature to form a thick oxide film. The method for manufacturing a semiconductor device of the embodiments of the present application forms a first film containing a metal element and oxygen (O) and having a first thickness over a semiconductor layer containing silicon (Si), and forms a second film containing silicon (Si) and oxygen (O) and having a second thickness thicker than the first thickness between the semiconductor layer and the first film by radical oxidation.

Description

[0001] Related applications

[0002] This application claims priority to Japanese Patent Application No. 2021-131790 (filed on August 12, 2021). This application incorporates the entire contents of the basic application by reference to that basic application. Technical Field

[0003] The embodiments of the present invention relate to a method for manufacturing a semiconductor device. Background Technology

[0004] In the manufacture of semiconductor devices, it is desirable to realize a method to oxidize semiconductor layers at low temperatures to form a thick oxide film. Summary of the Invention

[0005] Embodiments of the present invention provide a method for manufacturing a semiconductor device by oxidizing a semiconductor layer at low temperature to form a thick oxide film.

[0006] The method for manufacturing a semiconductor device according to the embodiment involves forming a first film containing a metal element and oxygen (O) and having a first thickness on a semiconductor layer containing silicon (Si), and forming a second film containing silicon (Si) and oxygen (O) and having a second thickness greater than the first thickness between the semiconductor layer and the first film by free radical oxidation. Attached Figure Description

[0007] Figures 1(a) to (c) are explanatory diagrams of the manufacturing method of the semiconductor device according to the first embodiment.

[0008] Figure 2 This is an explanatory diagram illustrating the operation and effects of the semiconductor device manufacturing method according to the first embodiment.

[0009] Figure 3 (a) to (c) are explanatory diagrams of the manufacturing method of the semiconductor device according to the second embodiment.

[0010] Figure 4 This is an explanatory diagram illustrating the operation and effects of the semiconductor device manufacturing method according to the second embodiment.

[0011] Figure 5 This is a schematic cross-sectional view of a semiconductor device manufactured using the semiconductor device manufacturing method of the third embodiment.

[0012] Figure 6 (a) to (d) are explanatory diagrams of the manufacturing method of the semiconductor device according to the third embodiment.

[0013] Figure 7 (a) to (d) are explanatory diagrams of variations of the manufacturing method of the semiconductor device according to the third embodiment.

[0014] Figure 8 This is a schematic cross-sectional view of a semiconductor device manufactured using the semiconductor device manufacturing method of the fourth embodiment.

[0015] Figure 9 (a) to (d) are explanatory diagrams of the manufacturing method of the semiconductor device according to the fourth embodiment.

[0016] Figure 10 This is a schematic cross-sectional view of a semiconductor device manufactured using the semiconductor device manufacturing method of the fifth embodiment.

[0017] Figure 11 (a) to (d) are explanatory diagrams of the manufacturing method of the semiconductor device according to the fifth embodiment.

[0018] Figure 12 This is a schematic cross-sectional view of a semiconductor device manufactured using the semiconductor device manufacturing method of the sixth embodiment.

[0019] Figure 13 (a) to (d) are explanatory diagrams of the manufacturing method of the semiconductor device according to the sixth embodiment.

[0020] Explanation of reference numerals in the attached figures

[0021] 10 Semiconductor Layer

[0022] 10a First p-type semiconductor region (Region 1)

[0023] 10b Second p-type semiconductor region (region 2)

[0024] 12. Alumina film (film 1)

[0025] 14. Silica film (second film)

[0026] 16. Silicon oxynitride film (3rd film)

[0027] 18 Hafnium oxide film (4th film)

[0028] 102 First gate electrode

[0029] 202 Second gate electrode

[0030] d1 First thickness

[0031] d2 Second thickness

[0032] d3 Third thickness

[0033] d4 4th thickness Detailed Implementation

[0034] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, in the following description, the same or similar components will be marked with the same symbols, and the description of components that have been described once will sometimes be appropriately omitted.

[0035] Additionally, for convenience, the terms "upper" or "lower" are sometimes used in this specification. "Upper" or "lower" refers, for example, to a relative positional relationship in a diagram. The terms "upper" or "lower" do not necessarily specify a positional relationship relative to gravity.

[0036] Qualitative and quantitative analyses of the chemical composition of the components constituting the semiconductor device described in this specification can be performed, for example, using secondary ion mass spectrometry (SIMS) or energy dispersive X-ray spectroscopy (EDX). Furthermore, measurements of the thickness of the components constituting the semiconductor device, the distance between components, etc., can be performed using, for example, a transmission electron microscope (TEM).

[0037] (First Embodiment)

[0038] The semiconductor device manufacturing method of the first embodiment involves forming a first film containing a metal element and oxygen (O) and having a first thickness on a semiconductor layer containing silicon (Si), and forming a second film containing silicon (Si) and oxygen (O) and having a second thickness greater than the first thickness between the semiconductor layer and the first film by free radical oxidation.

[0039] Figures 1(a) to (c) are explanatory diagrams of the manufacturing method of the semiconductor device according to the first embodiment.

[0040] First, a semiconductor layer 10 is prepared (Figure 1(a)). The semiconductor layer 10 contains silicon (Si). The semiconductor layer 10 is, for example, mainly composed of silicon (Si). The semiconductor layer 10 is, for example, a monocrystalline silicon layer or a polycrystalline silicon layer.

[0041] The semiconductor layer 10 is not limited to a single-crystal silicon layer or a polycrystalline silicon layer. For example, the semiconductor layer 10 can be a silicon germanide layer or a silicon carbide layer. Hereinafter, the case where the semiconductor layer 10 is a single-crystal silicon layer will be described as an example.

[0042] Next, an aluminum oxide film 12 is formed on the semiconductor layer 10 (Fig. 1(b)). The aluminum oxide film 12 is an example of the first film. Aluminum (Al) is an example of a metallic element.

[0043] The alumina film 12 is formed, for example, by chemical vapor deposition (CVD). The alumina film 12 is also formed, for example, by atomic layer deposition (ALD).

[0044] The first film contains a metallic element and oxygen (O). The metallic element in the first film is, for example, at least one selected from aluminum (Al), hafnium (Hf), zirconium (Zr), lanthanum (La), yttrium (Y), titanium (Ti), nickel (Ni), zinc (Zn), indium (In), tin (Sn), gallium (Ga), and tungsten (W). The first film is, for example, primarily composed of the aforementioned metallic element and oxygen (O). The first film is, for example, a metal oxide film. The first film is, for example, an oxide film of the aforementioned metallic element.

[0045] The first film is, for example, an aluminum oxide film, a hafnium oxide film, a zirconium oxide film, a lanthanum oxide film, a yttrium oxide film, a titanium oxide film, a nickel oxide film, a zinc oxide film, an indium oxide film, a tin oxide film, a gallium oxide film, or a tungsten oxide film.

[0046] The first membrane is, for example, an insulating membrane or a semiconductor membrane. The first membrane is, for example, an amorphous membrane. The first membrane contains, for example, at least one element selected from nitrogen (N), carbon (C), hydrogen (H), fluorine (F), and chlorine (Cl).

[0047] The first film has a first thickness (d1 in Figures 1(b) and 1(c)). The first thickness d1 is, for example, 1 nm or more and 5 nm or less. The first thickness d1 of the alumina film 12 is, for example, 1 nm or more and 5 nm or less.

[0048] The first film is not necessarily limited to an alumina film. The following explanation will take the case where the first film is an alumina film as an example.

[0049] Next, a silicon oxide film 14 with a second thickness (d2 in FIG. 1(c)) that is thicker than the first thickness d1 is formed between the semiconductor layer 10 and the aluminum oxide film 12 using free radical oxidation (FIG. 1(c)). The silicon oxide film 14 is formed by oxidizing the semiconductor layer 10 using free radical oxidation. The silicon oxide film 14 is an example of the second film.

[0050] Free radical oxidation is carried out in an atmosphere containing oxygen radicals or hydroxyl radicals. For example, it is carried out in an atmosphere plasma-enhanced with oxygen, hydrogen, or argon. Free radical oxidation is also carried out in an atmosphere plasma-enhanced with water vapor.

[0051] The methods for generating oxygen and hydroxyl radicals used in free radical oxidation are not particularly limited. Oxygen and hydroxyl radicals can be generated, for example, by inductively coupled plasma, microwave plasma, electron cyclotron resonance, helical wave, or hot filament.

[0052] The atmosphere for free radical oxidation contains, for example, hydrogen (H) and oxygen (O). The atomic ratio of hydrogen (H) in the atmosphere for free radical oxidation to the sum of hydrogen (H) and oxygen (O) (H / (H+O)) is, for example, 40% or less. The atomic ratio of hydrogen (H) in the atmosphere for free radical oxidation to the sum of hydrogen (H) and oxygen (O) (H / (H+O)) is, for example, 2% or more and 5% or less.

[0053] The atomic ratio of hydrogen (H) in the atmosphere for free radical oxidation relative to the sum of hydrogen (H) and oxygen (O) (H / (H+O)) is adjusted, for example, by the flow rates of hydrogen (H2) and oxygen (O2) introduced into the atmosphere for free radical oxidation. The molar ratio of hydrogen (H2) introduced into the atmosphere for free radical oxidation relative to the sum of hydrogen (H2) and oxygen (O2) (H2 / (H2+O2)) is, for example, 40% or less. The molar ratio of hydrogen (H2) introduced into the atmosphere for free radical oxidation relative to the sum of hydrogen (H2) and oxygen (O2) (H2 / (H2+O2)) is, for example, 2% or more and 5% or less.

[0054] The temperature for free radical oxidation is, for example, above 300°C and below 900°C. The pressure for free radical oxidation is, for example, above 50 Pa and below 3000 Pa.

[0055] The second film contains silicon (Si) and oxygen (O). For example, the second film is mainly composed of silicon (Si) and oxygen (O).

[0056] The second film has a second thickness (d2 in Figure 1(c)). The second thickness d2 is thicker than the first thickness d1 of the first film. The second thickness d2 is, for example, more than 10 times the first thickness d1 of the first film. The second thickness d2 is, for example, more than 10 nm and less than 300 nm.

[0057] The second thickness d2 of the silicon oxide film 14 is thicker than the first thickness d1 of the aluminum oxide film 12. The second thickness d2 of the silicon oxide film 14 is, for example, more than 10 times the first thickness d1 of the aluminum oxide film 12. The second thickness d2 of the silicon oxide film 14 is, for example, more than 10 nm and less than 300 nm.

[0058] Next, the operation and effects of the semiconductor device manufacturing method of the first embodiment will be explained.

[0059] In the manufacture of semiconductor devices, it is desirable to achieve a method for forming a thick oxide film by oxidizing a semiconductor layer at low temperatures. For example, by oxidizing the semiconductor layer at low temperatures, it is possible to suppress the degradation of the characteristics of the device formed on the semiconductor layer.

[0060] For example, in the manufacture of semiconductor devices containing transistors, if high-temperature heat treatment is applied after transistor formation, there is a risk of impurity diffusion and degradation of the transistor's constituent materials due to heat treatment, thereby degrading the transistor's characteristics. If the oxide film formed after transistor formation can be performed at low temperature, the degradation of transistor characteristics can be suppressed.

[0061] The semiconductor device manufacturing method of the first embodiment utilizes free radical oxidation in the oxidation of the semiconductor layer. By utilizing free radical oxidation, for example, compared with thermal oxidation, the semiconductor layer can be oxidized at a low temperature.

[0062] Figure 2 This is an explanatory diagram illustrating the operation and effects of the semiconductor device manufacturing method according to the first embodiment. Figure 2 This is a graph showing the thickness of the oxide film formed by oxidizing the semiconductor layer through free radical oxidation.

[0063] Figure 2 This is a graph comparing the oxide film thickness with and without a second film formed on the semiconductor layer. Figure 2 This illustrates the case where the semiconductor layer is a single-crystal silicon layer and the second film is an aluminum oxide film. Figure 2 The diagram shows the case where the alumina film thickness is 3 nm and the free radical oxidation temperature is 700 °C.

[0064] Depend on Figure 2 It is clearly known that when free radical oxidation is performed by forming an aluminum oxide film 12 on the semiconductor layer 10, the oxide film thickness is more than 7 times that of the case where no aluminum oxide film 12 is formed. In other words, it is known that free radical oxidation by forming an aluminum oxide film 12 on the semiconductor layer 10 results in a significantly accelerated oxidation process.

[0065] occur Figure 2 The mechanism of such rapid oxidation as shown is not necessarily clear. However, it is believed that by having a film of coexisting metal elements and oxygen (O) on the silicon-containing semiconductor layer 10, the activation energy for oxide film formation is reduced, resulting in rapid oxidation. Another theory suggests that oxygen deficiencies in the metal oxide are filled by oxygen free radicals and hydroxyl free radicals, and oxygen in the metal oxide is expelled by the subsequent intrusion of oxygen and hydroxyl free radicals into the metal oxide, resulting in rapid oxidation.

[0066] In the semiconductor device manufacturing method of the first embodiment, the first film is preferably amorphous. Because the first film is amorphous, the degree of oxidation is increased.

[0067] In the semiconductor device manufacturing method of the first embodiment, the first thickness d1 of the first film is preferably 0.5 nm or more, and more preferably 1 nm or more. When the first thickness d1 is 0.5 nm or more, the degree of accelerated oxidation increases; when the first thickness d1 is 1 nm or more, the degree of accelerated oxidation further increases.

[0068] Furthermore, in the semiconductor device manufacturing method of the first embodiment, the first thickness d1 of the first film is preferably 5 nm or less, more preferably 3 nm or less. By having a first thickness d1 of 5 nm or less, the degree of accelerated oxidation increases. Furthermore, by having a first thickness d1 of 3 nm or less, the degree of accelerated oxidation further increases.

[0069] In the semiconductor device manufacturing method of the first embodiment, the temperature for free radical oxidation is preferably 300°C or higher, more preferably 400°C or higher, and even more preferably 500°C or higher. As the temperature of free radical oxidation increases, the degree of oxidation accelerates.

[0070] In the semiconductor device manufacturing method of the first embodiment, the temperature of free radical oxidation is preferably 900°C or lower, more preferably 800°C or lower, and even more preferably 700°C or lower. By lowering the temperature of free radical oxidation, for example, it is possible to suppress the degradation of the characteristics of the device formed on the semiconductor layer.

[0071] In the semiconductor device manufacturing method of the first embodiment, the first film preferably contains at least one element selected from nitrogen (N), carbon (C), hydrogen (H), and chlorine (Cl). By including the above-mentioned element in the first film, crystallization of the first film is suppressed, and the degree of accelerated oxidation is increased.

[0072] In the semiconductor device manufacturing method of the first embodiment, the atmosphere for free radical oxidation includes hydrogen (H) and oxygen (O). The atomic ratio of the included hydrogen (H) to the sum of hydrogen (H) and oxygen (O) (H / (H+O)) is preferably 40% or less, more preferably 2% or more and 5% or less. By satisfying the above range for the atomic ratio (H / (H+O)), the degree of accelerated oxidation increases.

[0073] According to the semiconductor device manufacturing method of the first embodiment, a thick oxide film can be formed by oxidizing the semiconductor layer at a low temperature.

[0074] (Second Implementation)

[0075] The semiconductor device manufacturing method of the second embodiment differs from the semiconductor device manufacturing method of the first embodiment in that a third film comprising silicon (Si), oxygen (O), and nitrogen (N) is formed on the semiconductor layer before the first film is formed on the semiconductor layer. Hereinafter, descriptions that are repeated in the first embodiment will sometimes be omitted.

[0076] Figure 3 (a) to (c) are explanatory diagrams of the manufacturing method of the semiconductor device according to the second embodiment.

[0077] First, prepare semiconductor layer 10 ( Figure 3 (a) The semiconductor layer 10 comprises silicon (Si). The semiconductor layer 10 is, for example, primarily composed of silicon (Si). The semiconductor layer 10 is, for example, a monocrystalline silicon layer or a polycrystalline silicon layer.

[0078] Next, a silicon oxynitride film 16 is formed on the semiconductor layer 10. The silicon oxynitride film 16 is an example of the third film.

[0079] The silicon oxynitride film 16 is formed, for example, by CVD. The silicon oxynitride film 16 is formed, for example, by ALD.

[0080] The third film comprises silicon (Si), oxygen (O), and nitrogen (N). For example, the third film is mainly composed of silicon (Si), oxygen (O), and nitrogen (N).

[0081] The thickness of the third film is, for example, 1 nm or more and 10 nm or less. The thickness of the silicon oxynitride film 16 is, for example, 1 nm or more and 10 nm or less.

[0082] Next, an aluminum oxide film 12 is formed on the semiconductor layer 10. Figure 3 (b)). Alumina film 12 is an example of the first film.

[0083] The first film comprises a metallic element and oxygen (O). The metallic element included in the first film is, for example, at least one selected from aluminum (Al), hafnium (Hf), zirconium (Zr), lanthanum (La), yttrium (Y), titanium (Ti), nickel (Ni), zinc (Zn), indium (In), tin (Sn), gallium (Ga), and tungsten (W). The first film is, for example, primarily composed of the aforementioned metallic element and oxygen (O). The first film is, for example, a metal oxide film.

[0084] The first membrane has a first thickness ( Figure 3 (b) Figure 3 (c) d1). The first thickness d1 is, for example, 1 nm or more and 5 nm or less. The first thickness d1 of the alumina film 12 is, for example, 1 nm or more and 5 nm or less.

[0085] Next, a second thickness (d1) is formed between the semiconductor layer 10 and the aluminum oxide film 12 by free radical oxidation. Figure 3 (c) d2) silicon oxide film 14 ( Figure 3 (c)). A silicon oxide film 14 is formed between the semiconductor layer 10 and the silicon oxynitride film 16.

[0086] A silicon oxide film 14 is formed by oxidizing the semiconductor layer 10 using free radical oxidation. The silicon oxide film 14 is an example of the second film.

[0087] The second film contains silicon (Si) and oxygen (O). For example, the second film is mainly composed of silicon (Si) and oxygen (O).

[0088] The second membrane has a second thickness ( Figure 3 (d2 in (c)). The second thickness d2 is thicker than the first thickness d1 of the first film. The second thickness d2 is, for example, more than 10 times the first thickness d1 of the first film. The second thickness d2 is, for example, more than 10 nm and less than 600 nm. The second thickness d2 is thicker than the thickness of the third film.

[0089] The second thickness d2 of the silicon oxide film 14 is thicker than the first thickness d1 of the aluminum oxide film 12. The second thickness d2 of the silicon oxide film 14 is, for example, more than 10 times the first thickness d1 of the aluminum oxide film 12. The second thickness d2 of the silicon oxide film 14 is, for example, more than 10 nm and less than 600 nm. The second thickness d2 is thicker than the thickness of the silicon oxynitride film 16.

[0090] Next, the operation and effects of the semiconductor device manufacturing method of the second embodiment will be explained.

[0091] Figure 4 This is an explanatory diagram illustrating the operation and effects of the semiconductor device manufacturing method according to the second embodiment. Figure 4 This is a diagram showing the thickness of the oxide film formed by oxidizing a semiconductor layer through free radical oxidation.

[0092] Figure 4 This is a graph comparing the oxide film thicknesses when a third film and a second film are formed on the semiconductor layer, when only a second film is formed, and when neither a third film nor a second film is formed. Figure 4 This illustrates a case where the semiconductor layer is a single-crystal silicon layer, the third film is a silicon oxynitride film, and the second film is an aluminum oxide film. Figure 4 The diagram shows the case where the thickness of the silicon oxynitride film is 8 nm, the thickness of the aluminum oxide film is 3 nm, and the free radical oxidation temperature is 700 °C.

[0093] Depend on Figure 4It is clearly known that when free radical oxidation is performed by forming a silicon oxynitride film 16 and an aluminum oxide film 12 on the semiconductor layer 10, the oxide film thickness is more than 26 times greater than that when no silicon oxynitride film 16 and aluminum oxide film 12 are formed. Furthermore, it is known that when free radical oxidation is performed by forming a silicon oxynitride film 16 and an aluminum oxide film 12 on the semiconductor layer 10, the oxide film thickness is more than 3 times greater than that when only an aluminum oxide film 12 is formed. Therefore, it is clear that free radical oxidation by forming a silicon oxynitride film 16 and an aluminum oxide film 12 on the semiconductor layer 10 results in a significantly accelerated oxidation process.

[0094] According to the semiconductor device manufacturing method of the second embodiment, a thick oxide film can be formed by oxidizing the semiconductor layer at a low temperature.

[0095] (Third Implementation)

[0096] The semiconductor device manufacturing method of the third embodiment involves forming a first film containing a first metal element and oxygen (O) and having a first thickness on at least a first region of a semiconductor layer containing silicon (Si) and including a first region and a second region. A second film containing silicon (Si) and oxygen (O) is formed between the first region and the first film, and on the second region, using free radical oxidation. This second film has a second thickness that is thicker than the first thickness on the first region and a third thickness that is thinner than the second thickness on the second region. The first film is selectively formed on the first region. Hereinafter, descriptions that are repeated in the first embodiment will sometimes be omitted.

[0097] Figure 5 This is a schematic cross-sectional view of a semiconductor device manufactured using the semiconductor device manufacturing method of the third embodiment. The semiconductor device includes a first transistor 100 and a second transistor 200. The first transistor 100 and the second transistor 200 are metal-oxide field-effect transistors (MOSFETs).

[0098] The first transistor 100 includes a semiconductor layer 10, a first gate insulating layer 101, and a first gate electrode 102. The semiconductor layer 10 includes a first p-type semiconductor region 10a and an n-type semiconductor region 10x. The first gate insulating layer 101 includes a first lower film 101a and a first upper film 101b.

[0099] Semiconductor layer 10 is, for example, a single-crystal silicon layer. The portion of the first p-type semiconductor region 10a facing the first gate electrode 102 functions as the channel region of the first transistor 100. The n-type semiconductor region 10x functions as the source and drain regions of the first transistor 100.

[0100] The first lower film 101a of the first gate insulating layer 101 contains silicon (Si) and oxygen (O). The first lower film 101a is, for example, a silicon oxide film. The first upper film 101b of the first gate insulating layer 101 contains a first metal element and oxygen (O). The first upper film 101b is, for example, an aluminum oxide film. Aluminum (Al) is an example of the first metal element.

[0101] The first gate electrode 102 is a conductor. The first gate electrode 102 is, for example, polycrystalline silicon containing p-type or n-type impurities.

[0102] The second transistor 200 includes a semiconductor layer 10, a second gate insulating layer 201, and a second gate electrode 202. The semiconductor layer 10 includes a second p-type semiconductor region 10b and an n-type semiconductor region 10x.

[0103] The portion of the second p-type semiconductor region 10b facing the second gate electrode 202 functions as the channel region of the second transistor 200. The n-type semiconductor region 10x functions as the source and drain regions of the second transistor 200.

[0104] The second gate insulating layer 201 comprises silicon (Si) and oxygen (O). The second gate insulating layer 201 is, for example, a silicon oxide film.

[0105] The second gate electrode 202 is a conductor. The second gate electrode 202 is, for example, polycrystalline silicon containing p-type or n-type impurities.

[0106] The thickness of the first gate insulating layer 101 of the first transistor 100 is greater than the thickness of the second gate insulating layer 201 of the second transistor 200.

[0107] By making the first gate insulating layer 101 of the first transistor 100 thicker than the second gate insulating layer 201 of the second transistor 200, the first transistor 100 can operate at a higher driving voltage than the second transistor 200.

[0108] Figure 6 (a) to (d) are explanatory diagrams of the manufacturing method of the semiconductor device according to the third embodiment.

[0109] First, prepare semiconductor layer 10 ( Figure 6 (a) The semiconductor layer 10 comprises silicon (Si). The semiconductor layer 10 is, for example, primarily composed of silicon (Si). The semiconductor layer 10 is, for example, a monocrystalline silicon layer or a polycrystalline silicon layer.

[0110] Semiconductor layer 10 is not limited to a single-crystal silicon layer or a polycrystalline silicon layer. Semiconductor layer 10 may also be, for example, a silicon germanide layer or a silicon carbide layer. Hereinafter, the case where semiconductor layer 10 is a single-crystal silicon layer will be described as an example.

[0111] The semiconductor layer 10 includes a first p-type semiconductor region 10a and a second p-type semiconductor region 10b.

[0112] Next, an aluminum oxide film 12 is formed on the semiconductor layer 10. Figure 6 (b)). Alumina film 12 is an example of the first film. A portion of alumina film 12 eventually becomes the first upper film 101b. Aluminum (Al) is an example of the first metallic element.

[0113] The alumina film 12 is formed, for example, by CVD. The alumina film 12 is formed, for example, by ALD.

[0114] The first film comprises a first metallic element and oxygen (O). The first metallic element in the first film is, for example, at least one metallic element selected from aluminum (Al), hafnium (Hf), zirconium (Zr), lanthanum (La), yttrium (Y), titanium (Ti), nickel (Ni), zinc (Zn), indium (In), tin (Sn), gallium (Ga), and tungsten (W). The first film is, for example, primarily composed of the aforementioned first metallic element and oxygen (O). The first film is, for example, a metal oxide film. The first film is, for example, an oxide film of the aforementioned first metallic element.

[0115] The first membrane is, for example, an insulating membrane or a semiconductor membrane. The first membrane is, for example, an amorphous membrane. The first membrane contains, for example, at least one element selected from nitrogen (N), carbon (C), hydrogen (H), and chlorine (Cl).

[0116] The first membrane has a first thickness ( Figure 6 (b) d1). The first thickness d1 is, for example, 1 nm or more and 5 nm or less. The first thickness d1 of the alumina film 12 is, for example, 1 nm or more and 5 nm or less.

[0117] The first film is not necessarily limited to an alumina film. The following explanation will take the case where the first film is an alumina film as an example.

[0118] Next, the aluminum oxide film 12 on the second p-type semiconductor region 10b is removed. Figure 6 (c) The aluminum oxide film 12 on the second p-type semiconductor region 10b is removed, for example, by wet etching. By removing the aluminum oxide film 12 on the second p-type semiconductor region 10b, the aluminum oxide film 12 is selectively formed on the first p-type semiconductor region 10a.

[0119] Next, a silicon oxide film 14 is formed on the semiconductor layer 10 using free radical oxidation. Figure 6 (d) A silicon oxide film 14 is formed on the first p-type semiconductor region 10a. A silicon oxide film 14 is formed between the first p-type semiconductor region 10a and the aluminum oxide film 12. A silicon oxide film 14 is formed on the second p-type semiconductor region 10b.

[0120] The silicon oxide film 14 above the first p-type semiconductor region 10a ultimately becomes the first lower film 101a. Furthermore, the silicon oxide film 14 above the second p-type semiconductor region 10b ultimately becomes the second gate insulating layer 201.

[0121] The second thickness of the silicon oxide film 14 between the first p-type semiconductor region 10a and the aluminum oxide film 12 ( Figure 6 (d) d2) is thicker than the first thickness d1 of the aluminum oxide film 12. The third thickness (d2) of the silicon oxide film 14 above the second p-type semiconductor region 10b is thicker than the first thickness d1 of the aluminum oxide film 12. Figure 6 (d) d3) is thinner than the second thickness d2 of the silicon oxide film 14.

[0122] A silicon oxide film 14 is formed by oxidizing the semiconductor layer 10 using free radical oxidation. The silicon oxide film 14 is an example of the second film.

[0123] The silicon oxide film 14 above the first p-type semiconductor region 10a becomes thicker than the silicon oxide film 14 above the second p-type semiconductor region 10b due to accelerated oxidation.

[0124] Free radical oxidation is carried out in an atmosphere containing oxygen radicals or hydroxyl radicals. For example, it is carried out in an atmosphere plasma-enhanced with oxygen, hydrogen, or argon. Free radical oxidation is also carried out in an atmosphere plasma-enhanced with water vapor.

[0125] The methods for generating oxygen and hydroxyl radicals used in free radical oxidation are not particularly limited. Oxygen and hydroxyl radicals can be generated, for example, by inductively coupled plasma, microwave plasma, electron cyclotron resonance, helical wave, or hot filament methods.

[0126] The atmosphere for free radical oxidation contains, for example, hydrogen (H) and oxygen (O). The atomic ratio of hydrogen (H) in the atmosphere for free radical oxidation to the sum of hydrogen (H) and oxygen (O) (H / (H+O)) is, for example, 40% or less. The atomic ratio of hydrogen (H) in the atmosphere for free radical oxidation to the sum of hydrogen (H) and oxygen (O) (H / (H+O)) is, for example, 2% or more and 5% or less.

[0127] The atomic ratio of hydrogen (H) in the atmosphere for free radical oxidation relative to the sum of hydrogen (H) and oxygen (O) (H / (H+O)) is adjusted, for example, by the flow rates of hydrogen (H2) and oxygen (O2) introduced into the atmosphere for free radical oxidation. The molar ratio of hydrogen (H2) introduced into the atmosphere for free radical oxidation relative to the sum of hydrogen (H2) and oxygen (O2) (H2 / (H2+O2)) is, for example, 40% or less. The molar ratio of hydrogen (H2) introduced into the atmosphere for free radical oxidation relative to the sum of hydrogen (H2) and oxygen (O2) (H2 / (H2+O2)) is, for example, 2% or more and 5% or less.

[0128] The temperature for free radical oxidation is, for example, above 300°C and below 900°C. The pressure for free radical oxidation is, for example, above 50 Pa and below 3000 Pa.

[0129] The second film contains silicon (Si) and oxygen (O). For example, the second film is mainly composed of silicon (Si) and oxygen (O).

[0130] The second film above the first p-type semiconductor region 10a has a second thickness ( Figure 6 (d) d2). The second film above the second p-type semiconductor region 10b has a third thickness ( Figure 6 (d3 in (d)).

[0131] The second thickness d2 is thicker than the first thickness d1 of the first film. The second thickness d2 is, for example, more than 10 times the first thickness d1 of the first film. The second thickness d2 is, for example, more than 10 nm and less than 300 nm.

[0132] The second thickness d2 of the silicon oxide film 14 is thicker than the first thickness d1 of the aluminum oxide film 12. The second thickness d2 of the silicon oxide film 14 is, for example, more than 10 times the first thickness d1 of the aluminum oxide film 12. The second thickness d2 of the silicon oxide film 14 is, for example, more than 10 nm and less than 300 nm.

[0133] The second thickness d2 is thicker than the third thickness d3. For example, the second thickness d2 is more than 7 times the third thickness d3.

[0134] The second thickness d2 of the silicon oxide film 14 is thicker than the third thickness d3 of the silicon oxide film 14. For example, the second thickness d2 of the silicon oxide film 14 is more than 7 times the third thickness d3 of the silicon oxide film 14.

[0135] Subsequently, by employing known process technologies to form the first gate electrode 102, the second gate electrode 202, and the n-type semiconductor region 10x, it is possible to manufacture... Figure 5The semiconductor device shown. A first gate electrode 102 is formed above a silicon oxide film 14 on a first p-type semiconductor region 10a. A second gate electrode 202 is formed above a silicon oxide film 14 on a second p-type semiconductor region 10b.

[0136] (Modified Example)

[0137] A variation of the semiconductor device manufacturing method of the third embodiment differs from the semiconductor device manufacturing method of the third embodiment in that a third film comprising silicon (Si), oxygen (O) and nitrogen (N) is formed on the first region before the formation of the first film.

[0138] Figure 7 (a) to (d) are explanatory diagrams of variations of the manufacturing method of the semiconductor device according to the third embodiment.

[0139] First, prepare semiconductor layer 10 ( Figure 7 (a)). Semiconductor layer 10 includes a first p-type semiconductor region 10a and a second p-type semiconductor region 10b.

[0140] Next, a silicon oxynitride film 16 is formed on the semiconductor layer 10. The silicon oxynitride film 16 is an example of the third film. Next, an aluminum oxide film 12 is formed on the semiconductor layer 10. Figure 7 (b)). Alumina film 12 is an example of the first film.

[0141] Next, the silicon oxynitride film 16 and aluminum oxide film 12 on the second p-type semiconductor region 10b are removed. Figure 7 (c) The silicon oxynitride film 16 and aluminum oxide film 12 on the second p-type semiconductor region 10b are removed, for example, by wet etching. By removing the silicon oxynitride film 16 and aluminum oxide film 12 on the second p-type semiconductor region 10b, the silicon oxynitride film 16 and aluminum oxide film 12 are selectively formed on the first p-type semiconductor region 10a.

[0142] Next, a silicon oxide film 14 is formed on the semiconductor layer 10 using free radical oxidation. Figure 7 (d) A silicon oxide film 14 is formed on the first p-type semiconductor region 10a. A silicon oxide film 14 is formed on the second p-type semiconductor region 10b.

[0143] A silicon oxide film 14 is formed by oxidizing the semiconductor layer 10 using free radical oxidation. The silicon oxide film 14 is an example of the second film.

[0144] The silicon oxide film 14 above the first p-type semiconductor region 10a becomes thicker than the silicon oxide film 14 above the second p-type semiconductor region 10b due to accelerated oxidation. In particular, by providing the silicon oxynitride film 16 above the first p-type semiconductor region 10a, accelerated oxidation is promoted compared to the semiconductor device manufacturing method of the third embodiment. Therefore, compared to the semiconductor device manufacturing method of the third embodiment, the second thickness ( ) of the silicon oxide film 14 above the first p-type semiconductor region 10a is increased. Figure 7 (b) d2) is the third thickness of the silicon oxide film 14 above the second p-type semiconductor region 10b. Figure 7 (b) The d3) thickness becomes easier.

[0145] Subsequently, by employing known process technologies to form the first gate electrode 102, the second gate electrode 202, and the n-type semiconductor region 10x, it is possible to manufacture a semiconductor with... Figure 5 The semiconductor device shown is the same semiconductor device.

[0146] According to the semiconductor device manufacturing method of the third embodiment and its variations, it is possible to oxidize the semiconductor layer at low temperature to form an oxide film of different thickness on the semiconductor layer.

[0147] (Fourth implementation)

[0148] The semiconductor device manufacturing method of the fourth embodiment involves forming a third film comprising silicon (Si), oxygen (O), and nitrogen (N) on a first region before forming the first film. Hereinafter, descriptions that are repeated in the third embodiment will sometimes be omitted.

[0149] Figure 8 This is a schematic cross-sectional view of a semiconductor device manufactured using the semiconductor device manufacturing method of the fourth embodiment. The semiconductor device includes a first transistor 100 and a second transistor 200. The first transistor 100 and the second transistor 200 are MOSFETs.

[0150] The first transistor 100 includes a semiconductor layer 10, a first gate insulating layer 101, and a first gate electrode 102. The semiconductor layer 10 includes a first p-type semiconductor region 10a and an n-type semiconductor region 10x. The first gate insulating layer 101 includes a first lower film 101a, an intermediate film 101c, and a first upper film 101b.

[0151] The first transistor 100 of the fourth embodiment differs from the first transistor 100 of the third embodiment in that its first gate insulating layer 101 includes an intermediate film 101c.

[0152] The first lower film 101a of the first gate insulating layer 101 comprises silicon (Si) and oxygen (O). The first lower film 101a is, for example, a silicon oxide film. The intermediate film 101c of the first gate insulating layer 101 comprises silicon (Si), oxygen (O), and nitrogen (N). The intermediate film 101c is, for example, a silicon oxynitride film. The first upper film 101b of the first gate insulating layer 101 comprises a first metal element and oxygen (O). The first upper film 101b is, for example, an aluminum oxide film.

[0153] The second transistor 200 includes a semiconductor layer 10, a second gate insulating layer 201, and a second gate electrode 202. The semiconductor layer 10 includes a second p-type semiconductor region 10b and an n-type semiconductor region 10x. The second gate insulating layer 201 includes a second lower film 201a and a second upper film 201b.

[0154] The second gate insulating layer 201 comprises silicon (Si) and oxygen (O). The second lower film 201a of the second gate insulating layer 201 is, for example, a silicon oxide film. The second upper film 201b of the second gate insulating layer 201 comprises a first metal element and oxygen (O). The second upper film 201b is, for example, an aluminum oxide film.

[0155] The thickness of the first gate insulating layer 101 of the first transistor 100 is greater than the thickness of the second gate insulating layer 201 of the second transistor 200.

[0156] Figure 9 (a) to (d) are explanatory diagrams of the manufacturing method of the semiconductor device according to the fourth embodiment.

[0157] First, prepare semiconductor layer 10 ( Figure 9 (a)). Semiconductor layer 10 includes a first p-type semiconductor region 10a and a second p-type semiconductor region 10b.

[0158] Next, a silicon oxynitride film 16 is formed on the semiconductor layer 10. The silicon oxynitride film 16 is an example of the third film. Then, the silicon oxynitride film 16 on the second p-type semiconductor region 10b is removed. Figure 9 (b) A silicon oxynitride film 16 is selectively formed on the first p-type semiconductor region 10a. The silicon oxynitride film 16 ultimately becomes the intermediate film 101c.

[0159] Next, an aluminum oxide film 12 is formed on the semiconductor layer 10. Figure 9 (c)). Alumina film 12 is an example of the first film. A portion of alumina film 12 eventually becomes the first upper film 101b. Another portion of alumina film 12 eventually becomes the second upper film 201b.

[0160] Next, a silicon oxide film 14 is formed on the semiconductor layer 10 using free radical oxidation. Figure 9(d) A silicon oxide film 14 is formed on the first p-type semiconductor region 10a. A silicon oxide film 14 is formed on the second p-type semiconductor region 10b.

[0161] The silicon oxide film 14 above the first p-type semiconductor region 10a ultimately becomes the first lower film 101a. Furthermore, the silicon oxide film 14 above the second p-type semiconductor region 10b ultimately becomes the second lower film 201a.

[0162] The second thickness of the silicon oxide film 14 between the first p-type semiconductor region 10a and the aluminum oxide film 12 ( Figure 9 (d) d2) is the first thickness of alumina film 12 ( Figure 9 (c) Figure 9 (d) refers to the thickness of d1). The third thickness of the silicon oxide film 14 above the second p-type semiconductor region 10b is ( Figure 9 (d) d3) is thinner than the second thickness d2 of the silicon oxide film 14.

[0163] A silicon oxide film 14 is formed by oxidizing the semiconductor layer 10 using free radical oxidation. The silicon oxide film 14 is an example of the second film.

[0164] The silicon oxide film 14 above the first p-type semiconductor region 10a becomes thicker than the silicon oxide film 14 above the second p-type semiconductor region 10b due to accelerated oxidation.

[0165] Subsequently, by employing known process technologies to form the first gate electrode 102, the second gate electrode 202, and the n-type semiconductor region 10x, it is possible to manufacture... Figure 8 The semiconductor device shown.

[0166] According to the semiconductor device manufacturing method of the fourth embodiment, the semiconductor layer can be oxidized at low temperature to form an oxide film of different thickness on the semiconductor layer.

[0167] (Fifth Embodiment)

[0168] The semiconductor device manufacturing method of the fifth embodiment involves forming a fourth film with a fourth thickness on a second region, comprising a second metal element different from the first metal element and oxygen (O), before forming the first film or after forming the first film and before forming the second film. The third thickness is thicker than the fourth thickness. This differs from the semiconductor device manufacturing method of the third embodiment in that the third embodiment has a fourth film. Hereinafter, descriptions that are repeated in the third embodiment will sometimes be omitted.

[0169] Figure 10This is a schematic cross-sectional view of a semiconductor device manufactured using the semiconductor device manufacturing method of the fifth embodiment. The semiconductor device includes a first transistor 100 and a second transistor 200. The first transistor 100 and the second transistor 200 are MOSFETs.

[0170] The first transistor 100 includes a semiconductor layer 10, a first gate insulating layer 101, and a first gate electrode 102. The semiconductor layer 10 includes a first p-type semiconductor region 10a and an n-type semiconductor region 10x. The first gate insulating layer 101 includes a first lower film 101a and a first upper film 101b.

[0171] The first lower film 101a of the first gate insulating layer 101 contains silicon (Si) and oxygen (O). The first lower film 101a is, for example, a silicon oxide film. The first upper film 101b of the first gate insulating layer 101 contains a first metallic element and oxygen (O). The first upper film 101b is, for example, an aluminum oxide film. Aluminum (Al) is an example of the first metallic element.

[0172] The second transistor 200 includes a semiconductor layer 10, a second gate insulating layer 201, and a second gate electrode 202. The semiconductor layer 10 includes a second p-type semiconductor region 10b and an n-type semiconductor region 10x. The second gate insulating layer 201 includes a second lower film 201a and a second upper film 201b.

[0173] The second transistor 200 of the fifth embodiment differs from the second transistor 200 of the third embodiment in that its second gate insulating layer 201 includes a second lower film 201a and a second upper film 201b.

[0174] The second gate insulating layer 201 comprises silicon (Si) and oxygen (O). The second lower film 201a of the second gate insulating layer 201 is, for example, a silicon oxide film. The second upper film 201b of the second gate insulating layer 201 comprises a second metal element different from the first metal element and oxygen (O). The second upper film 201b is, for example, a hafnium oxide film. Hafnium (Hf) is an example of the second metal element.

[0175] The thickness of the first gate insulating layer 101 of the first transistor 100 is greater than the thickness of the second gate insulating layer 201 of the second transistor 200.

[0176] Figure 11 (a) to (d) are explanatory diagrams of the manufacturing method of the semiconductor device according to the fifth embodiment.

[0177] First, prepare semiconductor layer 10 ( Figure 11 (a)). Semiconductor layer 10 includes a first p-type semiconductor region 10a and a second p-type semiconductor region 10b.

[0178] Next, an aluminum oxide film 12 is formed on the first p-type semiconductor region 10a of the semiconductor layer 10. Figure 11 (b)). Alumina film 12 is an example of the first film. Alumina film 12 eventually becomes the first upper film 101b. Aluminum (Al) is an example of the first metallic element.

[0179] The first membrane has a first thickness ( Figure 11 (b) d1). The alumina film 12 has a first thickness d1.

[0180] Next, a hafnium oxide film 18 is formed on the second p-type semiconductor region 10b of the semiconductor layer 10. The hafnium oxide film 18 is an example of the fourth film. The hafnium oxide film 18 is selectively formed on the second p-type semiconductor region 10b. The hafnium oxide film 18 ultimately becomes the second upper film 201b.

[0181] The fourth film contains a second metal element different from the first metal element and oxygen (O). Hafnium (Hf) is an example of a second metal element.

[0182] The fourth membrane has a fourth thickness. Figure 11 (c) Figure 11 (d) d4). The hafnium oxide film 18 has a fourth thickness d4.

[0183] Furthermore, the fourth film can also be formed before the first film. For example, it can also be manufactured by forming a hafnium oxide film 18 before forming an alumina film 12. Figure 11 The structure shown in (c)

[0184] Next, a silicon oxide film 14 is formed on the semiconductor layer 10 using free radical oxidation. Figure 11 (d) A silicon oxide film 14 is formed on the first p-type semiconductor region 10a. A silicon oxide film 14 is formed on the second p-type semiconductor region 10b.

[0185] A silicon oxide film 14 is formed by oxidizing the semiconductor layer 10 using free radical oxidation. The silicon oxide film 14 is an example of the second film.

[0186] The silicon oxide film 14 above the first p-type semiconductor region 10a ultimately becomes the first lower film 101a. Furthermore, the silicon oxide film 14 above the second p-type semiconductor region 10b ultimately becomes the second lower film 201a.

[0187] The second thickness of the silicon oxide film 14 between the first p-type semiconductor region 10a and the aluminum oxide film 12 ( Figure 11 (d) d2) is thicker than the first thickness d1 of the aluminum oxide film 12. The third thickness (d2) of the silicon oxide film 14 above the second p-type semiconductor region 10b is thicker than the first thickness d1 of the aluminum oxide film 12. Figure 11(d) d3) is thinner than the second thickness d2 of the silicon oxide film 14. The third thickness d3 of the silicon oxide film 14 above the second p-type semiconductor region 10b is thicker than the fourth thickness d4 of the hafnium oxide film 18.

[0188] The silicon oxide film 14 above the first p-type semiconductor region 10a becomes thicker than the silicon oxide film 14 above the second p-type semiconductor region 10b due to accelerated oxidation.

[0189] The degree of accelerated oxidation varies depending on the type of metal element contained in the film formed on the semiconductor layer 10 before free radical oxidation. For example, when the film contains aluminum (Al), accelerated oxidation is promoted compared to when the film contains hafnium (Hf). Furthermore, for example, when the film contains hafnium (Hf), accelerated oxidation is promoted compared to when the film contains zirconium (Zr). Additionally, for example, when the film contains zirconium (Zr), accelerated oxidation is promoted compared to when the film contains titanium (Ti).

[0190] The degree of accelerated oxidation varies depending on the type of film formed on the semiconductor layer 10 before free radical oxidation. For example, when the film is an aluminum oxide film, accelerated oxidation is promoted compared to when the film is a hafnium oxide film. Furthermore, for example, when the film is a hafnium oxide film, accelerated oxidation is promoted compared to when the film is a zirconium oxide film. Additionally, for example, when the film is a zirconium oxide film, accelerated oxidation is promoted compared to when the film is a titanium oxide film.

[0191] In the semiconductor device manufacturing method of the fifth embodiment, since the first film is an aluminum oxide film 12 and the fourth film is a hafnium oxide film 18, the accelerated oxidation of the first p-type semiconductor region 10a is promoted compared to the accelerated oxidation of the second p-type semiconductor region 10b. Therefore, the silicon oxide film 14 above the first p-type semiconductor region 10a becomes thicker than the silicon oxide film 14 above the second p-type semiconductor region 10b.

[0192] Subsequently, by employing known process technologies to form the first gate electrode 102, the second gate electrode 202, and the n-type semiconductor region 10x, it is possible to manufacture... Figure 10 The semiconductor device shown.

[0193] According to the semiconductor device manufacturing method of the fifth embodiment, the semiconductor layer can be oxidized at low temperature to form an oxide film of different thickness on the semiconductor layer.

[0194] (Sixth Embodiment)

[0195] The semiconductor device manufacturing method of the sixth embodiment also forms a first film on the second region. The thickness of the first film on the second region is different from the thickness of the first film on the first region. This is different from the semiconductor device manufacturing method of the third embodiment. Hereinafter, some descriptions that are repeated in the third embodiment will be omitted.

[0196] Figure 12 This is a schematic cross-sectional view of a semiconductor device manufactured using the semiconductor device manufacturing method of the sixth embodiment. The semiconductor device includes a first transistor 100 and a second transistor 200. The first transistor 100 and the second transistor 200 are MOSFETs.

[0197] The first transistor 100 includes a semiconductor layer 10, a first gate insulating layer 101, and a first gate electrode 102. The semiconductor layer 10 includes a first p-type semiconductor region 10a and an n-type semiconductor region 10x. The first gate insulating layer 101 includes a first lower film 101a and a first upper film 101b.

[0198] The first lower film 101a of the first gate insulating layer 101 contains silicon (Si) and oxygen (O). The first lower film 101a is, for example, a silicon oxide film. The first upper film 101b of the first gate insulating layer 101 contains a first metallic element and oxygen (O). The first upper film 101b is, for example, an aluminum oxide film. Aluminum (Al) is an example of the first metallic element.

[0199] The second transistor 200 includes a semiconductor layer 10, a second gate insulating layer 201, and a second gate electrode 202. The semiconductor layer 10 includes a second p-type semiconductor region 10b and an n-type semiconductor region 10x. The second gate insulating layer 201 includes a second lower film 201a and a second upper film 201b.

[0200] The second transistor 200 of the sixth embodiment differs from the second transistor 200 of the third embodiment in that its second gate insulating layer 201 includes a second lower film 201a and a second upper film 201b.

[0201] The second gate insulating layer 201 comprises silicon (Si) and oxygen (O). The second lower film 201a of the second gate insulating layer 201 is, for example, a silicon oxide film. The second upper film 201b of the second gate insulating layer 201 comprises a first metal element and oxygen (O). The second upper film 201b is, for example, an aluminum oxide film. Aluminum (Al) is an example of the first metal element.

[0202] The thickness of the first gate insulating layer 101 of the first transistor 100 is greater than the thickness of the second gate insulating layer 201 of the second transistor 200. The thickness of the first upper film 101b of the first transistor 100 is different from the thickness of the second upper film 201b of the second transistor 200. The thickness of the first upper film 101b of the first transistor 100 is thinner than the thickness of the second upper film 201b of the second transistor 200.

[0203] Figure 13 (a) to (d) are explanatory diagrams of the manufacturing method of the semiconductor device according to the sixth embodiment.

[0204] First, prepare semiconductor layer 10 ( Figure 13 (a)). Semiconductor layer 10 includes a first p-type semiconductor region 10a and a second p-type semiconductor region 10b.

[0205] Next, an aluminum oxide film 12 is selectively formed on the second p-type semiconductor region 10b of the semiconductor layer 10. Figure 13 (b)).

[0206] Next, an aluminum oxide film 12 is formed on the first p-type semiconductor region 10a and the second p-type semiconductor region 10b of the semiconductor layer 10. Figure 13 (c)). As a result, the thickness of the aluminum oxide film 12 above the second p-type semiconductor region 10b ( Figure 13 (b) d1') becomes thicker than the aluminum oxide film 12 above the first p-type semiconductor region 10a. Figure 13 (b) d1) thickness.

[0207] The aluminum oxide film 12 is an example of the first film. The aluminum oxide film 12 above the first p-type semiconductor region 10a eventually becomes the first upper film 101b. The aluminum oxide film 12 above the second p-type semiconductor region 10b eventually becomes the second upper film 201b. Aluminum (Al) is an example of the first metallic element.

[0208] Next, a silicon oxide film 14 is formed on the semiconductor layer 10 using free radical oxidation. Figure 13 (d) A silicon oxide film 14 is formed on the first p-type semiconductor region 10a. A silicon oxide film 14 is formed on the second p-type semiconductor region 10b.

[0209] A silicon oxide film 14 is formed by oxidizing the semiconductor layer 10 using free radical oxidation. The silicon oxide film 14 is an example of the second film.

[0210] The silicon oxide film 14 above the first p-type semiconductor region 10a ultimately becomes the first lower film 101a. Furthermore, the silicon oxide film 14 above the second p-type semiconductor region 10b ultimately becomes the second lower film 201a.

[0211] The second thickness of the silicon oxide film 14 between the first p-type semiconductor region 10a and the aluminum oxide film 12 ( Figure 13 (d) d2) is thicker than the first thickness d1 of the aluminum oxide film 12. The third thickness (d2) of the silicon oxide film 14 above the second p-type semiconductor region 10b is thicker than the first thickness d1 of the aluminum oxide film 12. Figure 13 (d) d3) is thinner than the second thickness d2 of the silicon oxide film 14.

[0212] The silicon oxide film 14 above the first p-type semiconductor region 10a becomes thicker than the silicon oxide film 14 above the second p-type semiconductor region 10b due to accelerated oxidation.

[0213] The degree of accelerated oxidation varies depending on the thickness of the first film formed on the semiconductor layer 10. For example, if the first film becomes thicker than a predetermined thickness, accelerated oxidation is suppressed. In this case, the predetermined thickness is, for example, 5 nm. Conversely, if the first film becomes thinner than a predetermined thickness, accelerated oxidation is suppressed. In this case, the predetermined thickness is, for example, 1 nm.

[0214] According to the semiconductor device manufacturing method of the sixth embodiment, by making the thickness of the aluminum oxide film 12 above the second p-type semiconductor region 10b greater than the thickness of the aluminum oxide film 12 above the first p-type semiconductor region 10a, accelerated oxidation is suppressed. Therefore, the silicon oxide film 14 above the first p-type semiconductor region 10a becomes thicker than the silicon oxide film 14 above the second p-type semiconductor region 10b.

[0215] Subsequently, by employing known process technologies to form the first gate electrode 102, the second gate electrode 202, and the n-type semiconductor region 10x, it is possible to manufacture... Figure 12 The semiconductor device shown.

[0216] According to the semiconductor device manufacturing method of the sixth embodiment, the semiconductor layer can be oxidized at low temperature to form an oxide film of different thickness on the semiconductor layer.

[0217] In embodiments 3 to 6, examples of forming gate insulating layers of different thicknesses were described. However, the semiconductor device manufacturing method of the present invention can also be applied in other cases, such as forming capacitor insulating layers of different thicknesses or forming oxide films of different thicknesses on the same semiconductor layer.

[0218] Several embodiments of the present invention have been described above, but these embodiments are shown as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. For example, the constituent elements of one embodiment can be replaced or modified with the constituent elements of other embodiments. These embodiments and their modifications are included in the scope and spirit of the invention, and are included within the scope of the invention as described in the claims and their equivalents.

Claims

1. A method for manufacturing a semiconductor device, A third film comprising silicon (Si), oxygen (O), and nitrogen (N) is formed on a semiconductor layer comprising silicon (Si), and a first film comprising a metal element and oxygen (O) and having a first thickness is formed on the third film. A second film containing silicon (Si) and oxygen (O) and having a second thickness greater than the first film is formed between the semiconductor layer and the third film by free radical oxidation.

2. The method for manufacturing a semiconductor device according to claim 1, wherein the first thickness is 1 nm or more and 5 nm or less.

3. The method for manufacturing a semiconductor device according to claim 1, wherein the second thickness is more than 10 times the first thickness.

4. The method for manufacturing a semiconductor device according to claim 1, wherein the temperature of the free radical oxidation is above 300°C and below 900°C.

5. The method for manufacturing a semiconductor device according to claim 1, wherein the first film comprises at least one element selected from nitrogen (N), carbon (C), hydrogen (H), fluorine (F), and chlorine (Cl).

6. The method for manufacturing a semiconductor device according to claim 1, wherein the free radical oxidizing atmosphere contains hydrogen (H) and oxygen (O), and the atomic ratio of hydrogen (H) to the sum of hydrogen (H) and oxygen (O) (H / (H+O)) is 40% or less.

7. The method for manufacturing a semiconductor device according to claim 1, wherein the free radical oxidation atmosphere contains hydrogen (H) and oxygen (O), and the atomic ratio of hydrogen (H) to the sum of hydrogen (H) and oxygen (O) (H / (H+O)) is 2% or more and 5% or less.

8. The method for manufacturing a semiconductor device according to claim 1, wherein the metal element is at least one selected from aluminum (Al), hafnium (Hf), zirconium (Zr), lanthanum (La), yttrium (Y), titanium (Ti), nickel (Ni), zinc (Zn), indium (In), tin (Sn), gallium (Ga), and tungsten (W).

9. The method for manufacturing a semiconductor device according to claim 1, wherein the semiconductor layer is a monocrystalline silicon layer or a polycrystalline silicon layer.

10. A method for manufacturing a semiconductor device, A third film comprising silicon (Si), oxygen (O), and nitrogen (N) is selectively formed on at least the first region of a semiconductor layer comprising silicon (Si) and comprising a first region and a second region. A first film comprising a first metal element and oxygen (O) and having a first thickness is formed on at least the third film. A second film containing silicon (Si) and oxygen (O) is formed between the first region and the third film and above the second region by free radical oxidation. The second film above the first region is thicker than the first film, and the third film above the second region is thinner than the second film.

11. The method of manufacturing a semiconductor device according to claim 10, wherein the first film is selectively formed on the first region.

12. The method for manufacturing a semiconductor device according to claim 10, A first gate electrode is formed above the second film in the first region. A second gate electrode is formed above the second film in the second region.

13. The method for manufacturing a semiconductor device according to claim 10, wherein the first thickness is 1 nm or more and 5 nm or less.

14. The method for manufacturing a semiconductor device according to claim 10, wherein the first metal element is at least one metal element selected from aluminum (Al), hafnium (Hf), zirconium (Zr), lanthanum (La), yttrium (Y), titanium (Ti), nickel (Ni), zinc (Zn), indium (In), tin (Sn), gallium (Ga), and tungsten (W).

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