KR20140071971A - Insulating film and production method for same - Google Patents

Abstract

A first silicon nitride film disposed on a substrate including oxygen atoms and a second silicon nitride film disposed in contact with the first silicon nitride film as an insulating film containing silicon atoms, fluorine atoms, and nitrogen atoms And an amount of the fluorine contained in the second silicon nitride film is set to be larger than the amount of fluorine contained in the first silicon nitride film and is provided with an oxide semiconductor layer containing indium atoms and oxygen atoms, , A semiconductor element having an insulating film containing a fluorine atom and a nitrogen atom is provided. This semiconductor element can be a thin film transistor.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an insulating film,

The present invention relates to an insulating film and a manufacturing method thereof. The present invention also relates to a semiconductor device having an insulating film and an oxide semiconductor layer.

BACKGROUND ART [0002] Recently, many semiconductor devices capable of manifesting various electrical functions using characteristics of semiconductors have been developed. As such a semiconductor element, for example, a thin film transistor used in a liquid crystal display device, a thin film EL (electroluminescence) display device, an organic EL display device and the like is known. Various studies have conventionally been conducted for the purpose of improving the performance of semiconductor devices including transistors.

For example, a manufacturing method of a semiconductor device in which a first interlayer insulating film, a second interlayer insulating film, and a third interlayer insulating film are sequentially layered on a basic insulating film is known (Japanese Patent No. 3148183 (Patent Document 1)).

The first and third interlayer insulating films are made of a silicon nitride film (SiN film) and the second interlayer insulating film is made of a silicon fluoride oxide film (SiOF film).

The SiN film as the first and third interlayer insulating films is formed by a plasma CVD (Chemical Vapor Deposition) method using silane fluoride (SiF ₄ ) gas and nitrogen (N ₂ ) gas as a material gas.

In this manufacturing method, since an SiN film is formed using a gas (SiF ₄ ) containing no hydrogen (H) atoms, an interlayer insulating film containing fluorine (F) is not exposed to H radicals during film formation, Can be suppressed.

Further, a thin film transistor (TFT) using amorphous In-Ga-Zn-oxide (a-IGZO) as a channel layer is known (Japanese Journal of Applied Physics 49 (2010) 03CB04 ).

This TFT has a structure in which a gate electrode, an insulating film and a-IGZO are sequentially laminated on a glass substrate, and a source electrode and a drain electrode are arranged on a-IGZO. The gate electrode is made of tungsten (W), the source electrode and the drain electrode are made of titanium (Ti), and the insulating film is made of silicon oxide (SiO _x ).

This TFT is manufactured by forming an a-IGZO film after forming an insulating film.

Conventionally, amorphous silicon layers have been widely used as channel layers of TFTs. Recently, oxide semiconductor layers such as IGZO have attracted attention as layers instead of amorphous silicon layers. The oxide semiconductor layer has an advantage that the carrier mobility is larger than that of the amorphous silicon layer. For example, Japanese Patent Laid-Open Publication No. 2008-199005 (Patent Document 2) discloses a technique for forming an amorphous oxide semiconductor layer by sputtering using a target made of a sintered body of oxide powder showing conductivity.

A semiconductor device such as a TFT has a layer having various roles in addition to a channel layer made of an oxide semiconductor layer. Conventionally, as a composition of these layers, a composition employed in combination with an oxide semiconductor layer is disclosed in JP-A-2010-073894 (Patent Document 3), and silicon oxides (SiO ₂ ) (SiN), yttrium oxide (Y ₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), hafnium oxide (Hf ₂ O ₂ ), and titanium oxide (TiO ₂ ).

Patent Document 1: Japanese Patent No. 3148183 Patent Document 2: Japanese Patent Application Laid-Open No. 2008-199005 Patent Document 3: Japanese Patent Application Laid-Open No. 2010-073894

Non-Patent Document 1: Hiromichi Godo, Daisuke Kawae, Shuhei Yoshitomi, Toshinari Sasaki, Shunichi Ito, Hiroki Ohara, Hideyuki Kishida, Masahiro Takahashi, Akiharu Miyanaga, and Shunpei Yamazaki, "Temperature Dependence of Transistor Characteristics and Electronic Structure for Amorphous In- -Zn-Oxide Thin Film Transistor ", Japanese Journal of Applied Physics 49 (2010) 03CB04.

However, in the manufacturing methods described in Patent Document 1 and Non-Patent Document 1, the problem that the electrical insulation performance is greatly lowered when an insulating film is formed on a material containing oxygen (O) atoms such as glass and a-IGZO It is difficult to do.

In the TFT using the oxide semiconductor layer described in Patent Documents 2 and 3 as the channel layer, when the voltage between the gate and the source and the voltage between the source and the drain is set to ± 20 V or more, the voltage is repeatedly swept The threshold value of the operating voltage (hereinafter also referred to as " Vth ") tends to change. For this reason, in the TFT using the oxide semiconductor layer, Vth is not stabilized and the current value flowing between the source and the drain is changed, resulting in a problem that the characteristics of the TFT are not stabilized.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the first invention is to provide an insulating film formed on a material containing oxygen (O) atoms with good insulating performance.

Another object of the first invention is to provide a manufacturing method for manufacturing an insulating film having good insulating performance on a material containing oxygen (O) atoms. The insulating film of the present invention is suitable for use as a constituent layer of a TFT.

It is a further object of the present invention to provide a semiconductor device using an oxide semiconductor layer, in which a change in Vth is suppressed and characteristics are stabilized.

The insulating film of the first invention is an insulating film containing silicon atoms, fluorine atoms and nitrogen atoms, and is provided with first and second silicon nitride films. The first silicon nitride film is disposed on a substrate containing oxygen atoms. The second silicon nitride film is disposed in contact with the first silicon nitride film. The amount of fluorine contained in the second silicon nitride film is larger than the amount of fluorine contained in the first silicon nitride film.

The first invention also relates to a manufacturing method of the above-mentioned insulating film, and a manufacturing method thereof is a manufacturing method of a semiconductor device including a main gas containing silicon atoms and fluorine atoms and a gas of a subsidiary gas composed of at least nitrogen gas A first step of depositing a first silicon nitride film on a substrate containing oxygen atoms by setting a flow rate ratio to a reference value or more; and a second step of depositing a first silicon nitride film on the first silicon nitride film by setting a gas flow rate ratio of the main gas and nitrogen gas to a value smaller than a reference value And depositing a second silicon nitride film in contact with the second silicon nitride film.

Here, it is preferable that the additive be composed of a gas containing a hydrogen atom and a gas containing an oxygen atom, and nitrogen gas.

Further, the additive may be composed of a gas containing a hydrogen atom and a nitrogen gas.

Further, the surface of the substrate may be covered with a metal, and the vortex may be composed of only nitrogen gas.

The second invention relates to a semiconductor device, which is a semiconductor device having an oxide semiconductor layer containing indium atoms and oxygen atoms, and an insulating film containing silicon atoms, fluorine atoms and nitrogen atoms.

In the semiconductor device, it is preferable that the oxide semiconductor layer and the insulating film are in contact with each other.

In the semiconductor device, it is preferable that the insulating film is at least one of a gate insulating film and a passivation film.

In the semiconductor device, the content of fluorine atoms in the insulating film is preferably greater than 0 atomic% and not greater than 30 atomic%.

In the semiconductor device, the insulating film further includes hydrogen atoms, and the content of hydrogen atoms in the insulating film is preferably greater than 0 atomic% and not greater than 7 atomic%.

In the semiconductor device, the insulating film further includes oxygen atoms, and the content of oxygen atoms in the insulating film is preferably greater than 0 atomic% and less than 25 atomic%.

In the semiconductor device, the insulating film is a gate insulating film, and the ratio (A / B) of the oxygen amount A in the semiconductor layer near the interface between the gate insulating film and the semiconductor layer to the oxygen amount B in the semiconductor layers other than the vicinity of the interface is It is preferably greater than 0.78 and less than 1. The ratio (A / B) is more preferably 0.8 or more and 0.98 or less.

In the semiconductor device, the insulating film is a passivation film. The ratio (C / D) of the oxygen amount C in the semiconductor layer near the interface between the passivation film and the semiconductor layer to the oxygen amount D in the semiconductor layers other than the vicinity of the interface is More preferably 1.05 or more and 1.3 or less.

In the semiconductor device, the semiconductor layer may include at least one selected from the group consisting of N, Al, Si, Ti, V, Cr, Zr, Nb, At least one element selected from the group consisting of molybdenum (Mo), hafnium (Hf), tantalum (Ta), tungsten (W), tin (Sn) and bismuth (Bi).

In the semiconductor element, it is preferable that the semiconductor element is a thin film transistor.

In the insulating film of the first invention, the fluorine concentration of the second silicon nitride film is larger than the fluorine concentration of the first silicon nitride film. That is, the fluorine concentration of the first silicon nitride film is smaller than the fluorine concentration of the second silicon nitride film. This is because the concentration of the F radical in the plasma at the time of forming the first silicon nitride film is made lower than the concentration of the F radical in the plasma at the time of forming the second silicon nitride film to form the first silicon nitride film .

Further, when the F radical in the plasma is reduced, the oxygen atoms are inhibited from being released from the substrate, and the oxygen atoms are inhibited from being absorbed into the first and second silicon nitride films. As a result, an insulating film having a high dielectric breakdown field strength and a small leakage current can be produced.

Therefore, if the fluorine concentration in the first silicon nitride film on the substrate side of the produced insulating film is lower than the fluorine concentration in the second silicon nitride film on the front surface side of the insulating film, mixing of oxygen atoms into the insulating film is reduced, Good insulation performance can be obtained.

In the method of manufacturing an insulating film according to the first aspect of the present invention, the first silicon nitride film is formed by setting the flow rate ratio of the main gas swab gas to a reference value or higher, and the flow ratio of the main gas swab gas is set to a value smaller than the reference value, A silicon nitride film is formed. As a result, the concentration of the F radical in the plasma at the time of forming the first silicon nitride film becomes lower than the concentration of the F radical in the plasma at the time of film formation of the second silicon nitride film, thereby suppressing the release of oxygen atoms from the substrate , And oxygen atoms are inhibited from being received in the first and second silicon nitride films.

Therefore, an insulating film having a high dielectric breakdown field strength and a small leakage current, that is, an insulating film having a good insulating performance can be produced.

According to the semiconductor device of the second invention, it is possible to provide a semiconductor device in which variations in Vth are suppressed and characteristics are stabilized.

1 is a cross-sectional view of an insulating film according to Embodiment 1 of the present invention.
2 is a cross-sectional view showing a configuration of a plasma apparatus according to Embodiment 1 of the present invention.
3 is a plan view of the planar conductor, the feed electrode, and the termination electrode viewed from the matching circuit side shown in Fig.
4 is a timing chart of the gas flow rate in the insulating film production method 1 shown in Fig.
5 is a diagram showing a method of measuring the electrical characteristics of the insulating film manufactured by the manufacturing method 1.
6 is a graph showing the relationship between the dielectric breakdown field strength and the leakage current density and the gas flow rate ratio in the insulating film manufactured by the manufacturing method 1.
7 is a process diagram showing the manufacturing method 1.
8 is a timing chart of the gas flow rate in the insulating film production method 2 shown in Fig.
9 is a diagram showing the relationship between the dielectric breakdown field strength and the leakage current density and the gas flow rate ratio in the insulating film manufactured by the manufacturing method 2.
10 is a process diagram showing Manufacturing Method 2.
11 is a timing chart of the gas flow rate in the insulating film production method 3 shown in Fig.
12 is a diagram showing a method of measuring the electrical characteristics of the insulating film manufactured by the manufacturing method 3. Fig.
Fig. 13 is a diagram showing the relationship between the leakage current and the gas flow rate in the insulating film manufactured by Manufacturing Method 3. Fig.
14 is a process diagram showing Manufacturing Method 3.
15 is a process diagram showing a method of manufacturing an insulating film according to the first embodiment of the present invention.
16 is a schematic cross-sectional view of an example of a TFT according to Embodiments 2 to 4 of the present invention.
17 is a schematic enlarged view of area A in Fig.
Fig. 18 is a cross-sectional view schematically showing a manufacturing process of the semiconductor device shown in Fig. 16;
19 is a schematic enlarged view of area B of Fig.

Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent parts are denoted by the same reference numerals and description thereof will not be repeated.

≪ Embodiment 1 >

Hereinafter, an insulating film which is an embodiment of the first invention in the present invention will be described.

«Insulating film»

1 is a sectional view of an insulating film according to Embodiment 1 of the first invention. Referring to Fig. 1, an insulating film 10 according to Embodiment 1 of the first invention comprises a substrate 1, a silicon nitride film 2, and a silicon nitride film 3. As shown in Fig.

The substrate 1 is made of glass and a material including O atoms such as a-IGZO. The silicon nitride film 2 is disposed in contact with a main surface of the substrate 1. [ The silicon nitride film 3 is disposed in contact with the silicon nitride film 2.

Each of the silicon nitride films 2 and 3 contains a fluorine atom and a hydrogen atom. Each of the silicon nitride films 2 and 3 has a hydrogen concentration of less than 5 atomic%. Further, the fluorine concentration of the silicon nitride film 3 is larger than the fluorine concentration of the silicon nitride film 2. The silicon nitride film 2 has a film thickness of 5 to 100 nm, for example, and the silicon nitride film 3 has a film thickness of 5 to 500 nm, for example.

«Plasma devices»

2 is a cross-sectional view showing a configuration of a plasma apparatus according to Embodiment 1 of the present invention. 2, the plasma apparatus 100 includes a vacuum container 20, an upper plate 22, an exhaust port 24, a gas inlet 26, a holder 32, a heater 34, The bearing 42, the partition plate 44, the plane conductor 50, the power supply electrode 52, the end electrode 54, A shield box 60, a high frequency power supply 62, a matching circuit 64 and connecting conductors 68 and 69. The flanges 56 and the packing 57 and 58 are connected to the shield boxes 60 and 60, respectively.

The vacuum container 20 is made of metal and connected to a vacuum exhaust device (not shown) through an exhaust port 24. Further, the vacuum container 20 is electrically connected to the ground node. The upper plate 22 is disposed in contact with the vacuum container 20 so as to cover the upper side of the vacuum container 20. In this case, a packing 57 for a vacuum seal is disposed between the vacuum container 20 and the upper plate 22.

The gas introducing portion 26 is disposed above the partition plate 44 in the vacuum container 20. [ The shaft 36 is fixed to the bottom surface of the vacuum container 20 through the bearing portion 38. The holder 32 is fixed to one end of the shaft 36. The heater (34) is disposed in the holder (32). The mask 42 is disposed on the holder 32 at the periphery of the holder 32. The partition plate 44 is fixed to the side wall of the vacuum container 20 so as to cover the space between the vacuum container 20 and the holder 32 above the holder 32.

The feed electrode 52 and the end electrode 54 are fixed to the top plate 22 through the insulating flange 56. In this case, a vacuum seal packing 58 is disposed between the top plate 22 and the insulating flange 56.

The planar conductor 50 is arranged so that both end portions in the X direction are in contact with the feed electrode 52 and the end electrode 54, respectively.

The feed electrode 52 and the end electrode 54 have substantially the same length as the plane conductor 50 in the Y direction (direction perpendicular to the plane of Fig. 2) as described later. The feeding electrode 52 is connected to the output bar 66 of the matching circuit 64 by the connecting conductor 68. [ The termination electrode 54 is connected to the shield box 60 via a connection conductor 69. The plane conductor 50, the feed electrode 52, and the end electrode 54 are made of, for example, copper and aluminum.

The shield box 60 is disposed on the upper side of the vacuum container 20 and is in contact with the upper plate 22. The high frequency power supply 62 is connected between the matching circuit 64 and the ground node. The matching circuit 64 is disposed on the shield box 60.

The connection conductors 68 and 69 are formed in a plate shape having substantially the same length as the feed electrode 52 and the termination electrode 54 in the Y direction.

The gas introducing section 26 supplies a gas 28 such as SiF ₄ gas, H ₂ gas and N ₂ gas supplied from a gas cylinder (not shown) into the vacuum container 20. The holder (32) supports the substrate (1). The heater 34 heats the substrate 1 to a desired temperature. The shaft 36 supports the holder 32. The mask 42 covers the periphery of the substrate 1. Thus, it is possible to prevent the insulating film from being formed on the periphery of the substrate 1. [ The partition plate 44 prevents the plasma 70 from reaching the holding mechanism of the substrate 1.

The feeding electrode 52 flows the high frequency current supplied from the connecting conductor 68 to the plane conductor 50. The termination electrode 54 connects the end of the planar conductor 50 directly or through a capacitor to a ground node to create a closed loop of high frequency current from the high frequency power supply 62 to the planar conductor 50.

The high-frequency power supply 62 supplies the high-frequency power of, for example, 13.56 MHz to the matching circuit 64. The matching circuit 64 supplies the high frequency power supplied from the high frequency power supply 62 to the connection conductor 68 while suppressing reflection.

3 is a plan view of the plane conductor 50, the feed electrode 52, and the terminal electrode 54 viewed from the matching circuit 64 side shown in Fig. Referring to Fig. 3, the planar conductor 50 has, for example, a rectangular planar shape and has sides 50a and 50b. The side 50a is longer than the side 50b. The side 50a is arranged along the X direction, and the side 50b is arranged along the Y direction.

The feed electrode 52 and the end electrode 54 are disposed at both ends in the X direction of the planar conductor 50 along the side 50b of the planar conductor 50, respectively. The length of the feeding electrode 52 and the longitudinal electrode 54 in the Y direction is set to be the same as the length of the side 50b parallel to the Y direction of the plane conductor 50 in order to uniformly flow the high- (For example, to be substantially equal to the length of the side 50b), but may be shorter or longer than the length of the side 50b. The length in the Y direction of the feed electrode 52 and the end electrode 54 may be set to 85% or more of the length of the side 50b.

As described above, since the feed electrode 52 and the end electrode 54 are formed of a block-shaped electrode, the high frequency current 14 can flow substantially uniformly to the planar conductor 50 in the Y direction.

Then, the plasma apparatus 100 generates an inductively coupled plasma by uniformly flowing the high-frequency current 14 to the plane conductor 50.

Then, an insulating film is deposited on the substrate provided on the holder 32 by the inductively coupled plasma generated in the vacuum container 20. Then, as shown in Fig.

<< Manufacturing Method 1 >>

4 is a timing chart of the gas flow rate in the manufacturing method 1 of the insulating film 10 shown in Fig.

In the manufacturing method 1 of the insulating film 10, the silicon nitride film 2 is deposited on the substrate 1 by using SiF ₄ gas, H ₂ gas and N ₂ gas, and then SiF ₄ gas and N ₂ The silicon nitride film 3 is deposited on the silicon nitride film 2 using a gas to produce the insulating film 10.

Further, the substrate 1 is made of patterned Mo / glass in which patterned molybdenum (Mo) is formed on glass. The film thickness of Mo is 100 nm, and the thickness of the glass is 0.5 mm. The width of Mo is 10 mu m and the interval of Mo is 20 mu m.

Furthermore, the substrate temperature was 150 占 폚, the pressure at the time of film formation was 2.6 Pa, and the high frequency power was 1.1 W / cm2.

In the case of manufacturing the insulating film 10 using the manufacturing method 1, the gas introducing portion 26 of the plasma apparatus 100 is operated at a rate of 25 sccm of SiF ₄ gas and 450 sccm of N ₂ gas And 200 sccm of H ₂ gas are supplied to the vacuum chamber 20.

The vacuum evacuation apparatus sets the pressure of the vacuum container 20 to 2.6 Pa. Further, the heater 34 sets the temperature of the substrate 1 at 150 占 폚.

Then, the high frequency power supply 62 supplies the planar conductor 50 with a high frequency power of 1.1 W / cm 2 through the matching circuit 64, the connecting conductor 68 and the feeding electrode 52.

As a result, a plasma is generated in the vacuum chamber 20, and a silicon nitride film 2 having a film thickness of 100 nm is deposited on the substrate 1. [

At the timing t2, the gas introducing section 26 increases the flow rate of the SiF ₄ gas from 25 sccm to 100 sccm, reduces the flow rate of the N ₂ gas from 450 sccm to 250 sccm, and stops the H ₂ gas . Thereafter, the gas introducing section 26 supplies 100 sccm of SiF ₄ gas and 250 sccm of N ₂ gas to the vacuum container 20 until timing t3.

As a result, the silicon nitride film 3 having a film thickness of 200 nm is deposited on the silicon nitride film 2.

Then, the gas supply 26, at time t3, and stops the SiF ₄ gas and N ₂ gas.

On the other hand, during the period from the timing t1 to the timing t3, the high-frequency power, the reaction pressure, and the substrate temperature are set to the above-described values.

Thus, in the production method 1, the substrate 1 (= patterned Mo / glass) film (2) silicon nitride which is disposed in contact with the can, the SiF ₄ main gas when forming the film 2, silicon nitride The H ₂ gas is added to the silicon nitride film 3, and the silicon nitride film 3 is formed without adding H ₂ gas to the SiF ₄ gas.

As a result, in the plasma at the time of forming the silicon nitride film 2, the F radical generated from the SiF ₄ gas reacts with the H radical generated from the H ₂ gas to become HF, and the F radical in the plasma (= Patterned Mo / glass), thereby inhibiting emission of oxygen atoms from the substrate 1 (= patterned Mo / glass).

Therefore, oxygen atoms in the substrate 1 (= patterned Mo / glass) are hardly received by the silicon nitride film 2. [

When the silicon nitride film 2 is formed, the F radicals generated from the SiF ₄ gas become HF. When the silicon nitride film 3 is formed, the F radicals generated from the SiF ₄ gas are not HF Therefore, the fluorine atoms are more absorbed in the silicon nitride film 3 than in the silicon nitride film 2. Therefore, the fluorine concentration of the silicon nitride film 3 becomes higher than the fluorine concentration of the silicon nitride film 2.

5 is a diagram showing a method of measuring the electrical characteristics of the insulating film manufactured by the manufacturing method 1.

Referring to FIG. 5, a silicon nitride film is deposited on patterned Mo / glass by Production Method 1. Then, an electrode is formed on the surface of the silicon nitride film.

A power source and an ammeter are connected in series between the electrode on the silicon nitride film and the Mo on the glass.

The power source applies a voltage in the film thickness direction of the silicon nitride film while changing the voltage value. Then, the ammeter measures the leakage current flowing through the silicon nitride film. The value obtained by dividing the voltage value applied by the power source by the thickness of the silicon nitride film is taken as the dielectric breakdown field strength.

6 is a graph showing the relationship between the dielectric breakdown field strength and the leakage current density and the gas flow rate ratio in the insulating film manufactured by the manufacturing method 1.

6, the vertical axis represents the dielectric breakdown field strength and the leakage current density, and the horizontal axis represents the ratio of the flow rate of the H ₂ gas to the flow rate of the SiF ₄ gas. The curve k1 shows the relationship between the dielectric breakdown field strength and the gas flow rate, and the curve k2 shows the relationship between the leakage current density and the gas flow rate. The flow rate of the SiF ₄ gas and the flow rate of the N ₂ gas were maintained at 25 sccm and 450 sccm, respectively, and the flow rates of the H ₂ gas were set to 0 sccm, 25 sccm, and 50 sccm, respectively (H ₂ / SiF ₄ ) , 100 sccm and 200 sccm, respectively.

6, the dielectric breakdown field strength, gas flow rate ratio (= H ₂ / SiF ₄₎ is 4 through the gas flow rate ratio (= H ₂ / SiF ₄₎ increased to thus becomes large, the gas flow rate ratio (= H ₂ / SiF ₄ in ) Becomes 4 or more, it increases finely beyond 5 [MV / cm] (see curve k1).

Then, the gas flow rate ratio (= H ₂ / SiF ₄₎ isolated growth of the breakdown field strength for the gas flow rate ratio (= H ₂ / SiF ₄₎ is larger by 4, and the gas flow rate ratio (= H ₂ / SiF ₄₎ is more than 4 , It becomes smaller. Accordingly, the gas flow rate of the breakdown field strength of insulation of the (= H ₂ / SiF _4), the gas flow rate ratio _{(= H 2 / SiF 4)} = to 4 as a boundary there is clearly changed, gas flow rate ratio (= H ₂ / SiF ₄ ) = 4 is a critical point.

In addition, the leakage current density, gas flow rate ratio (= H ₂ / SiF ₄₎ is 4 through the gas flow rate ratio (= H ₂ / SiF ₄₎ decreases with the increase of the gas flow rate ratio (= H ₂ / SiF ₄₎ is more than 4 When a, is about ^{1 × 10 -6 [a / ㎠} ] ( see the curve k2).

And, the gas flow rate of decrease of the leakage current density of the (= H ₂ / SiF _4), the gas flow rate ratio (= H ₂ / SiF ₄₎ is larger by 4, and the gas flow rate ratio (= H ₂ / SiF ₄₎ over 4 , It becomes smaller. Accordingly, the gas flow rate ratio (= H ₂ / SiF ₄₎ reduction of the leakage current density for the gas flow rate ratio _{(= H 2 / SiF 4)} = 4 I a is obviously changed in a boundary, the gas flow rate ratio (= H ₂ / SiF ₄ ) = 4 is the critical point.

As described above, the dielectric breakdown field intensity increases with an increase in the gas flow rate ratio (= H ₂ / SiF ₄ ) with the gas flow rate ratio (= H ₂ / SiF ₄ ) = 4 as the critical point, and the leakage current density increases with the gas flow rate ratio = H ₂ / SiF ₄ ) = 4 as a critical point, and decreases as the gas flow rate ratio (= H ₂ / SiF ₄ ) increases.

When the gas flow rate ratio (= H ₂ / SiF ₄ ) is 4 or more, the dielectric breakdown field intensity is about 5 MV / cm and the leakage current density is about 1 × 10 ^-6 [A / cm 2] (Silicon nitride film 2 / silicon nitride film 3) with good insulating performance can be manufactured. This is because, as described above, when the silicon nitride film 2 is formed, the F radicals in the plasma are reduced, so that the oxygen atoms in the substrate 1 (= patterned Mo / glass) This is because it is difficult to be accepted into the nitride film 2. [

Therefore, in order to produce an insulating film (silicon nitride film) having a small leakage current density and a high dielectric breakdown field strength by the manufacturing method 1, the gas flow rate ratio (= H ₂ / SiF ₄ )

As described above, by maintaining the flow rate of SiF ₄ gas and the flow rate of N ₂ gas at 25 sccm and 450 sccm, respectively, and changing the flow rate of H ₂ gas to 0 sccm, 25 sccm, 50 sccm, 100 sccm, and 200 sccm because it had to change the gas flow rate ratio (= H ₂ / SiF _4), the gas flow rate ratio (= H ₂ / SiF ₄₎ is 4 or more, the total ratio of the flow rate of N ₂ gas and H ₂ gas to the flow rate of SiF ₄ gas ( = (N ₂ gas + H ₂ gas) / SiF ₄ gas) becomes (N ₂ gas + H ₂ gas) / SiF ₄ gas = (450 + 100) / 25 = 22 or more.

Therefore, in the production method 1, SiF the total flow rate of the N ₂ gas and H ₂ gas to the flow rate of the _fourth gas ratio (= (N ₂ gas + H ₂ gas) / SiF ₄ gas), the (N ₂ gas + H ₂ The ratio of the flow rate of the N ₂ gas to the flow rate of the SiF ₄ gas (= N ₂ gas (gas) / SiF ₄ gas = (450 + 100) / 25 = / SiF ₄ gas) was set to N ₂ gas / SiF ₄ gas = 250/100 = 2.5 to form the silicon nitride film 3.

Therefore, when the SiF ₄ gas is used as the main gas and the N ₂ gas and the H ₂ gas are used as the auxiliary gas, the silicon nitride film 2 has a ratio of the flow rate of the sub gas to the flow rate of the main gas, And the silicon nitride film 3 is formed by setting the ratio of the flow rate of the secondary gas to the flow rate of the main gas to a value (= 2.5) smaller than the reference value (= 22).

On the other hand, in the manufacturing method 1, the silicon nitride film 2 may be formed using ammonia (NH ₃ ) gas instead of the H ₂ gas. Generally, a silicon nitride film 2) may be formed.

7 is a process diagram showing the manufacturing method 1. 7, when the production of the insulating film 10 is started, the ratio of the total flow rate of the gas including the hydrogen atoms to the flow rate of the SiF ₄ gas and the N ₂ gas is set to be not less than the reference value, The silicon nitride film 2 is formed (step S1).

Then, the silicon nitride film 3 is formed on the silicon nitride film 2 by setting the ratio of the flow rate of the N ₂ gas to the flow rate of the SiF ₄ gas to a value smaller than the reference value (step S 2).

Thus, the production of the insulating film 10 using the manufacturing method 1 is completed.

<< Manufacturing Method 2 >>

8 is a timing chart of the gas flow rate in the manufacturing method 2 of the insulating film 10 shown in Fig.

In the production method 2 of the insulating film 10, the substrate 1 a after the plasma treatment, to change the ratio of the flow rate of N ₂ gas to the flow rate of SiF ₄ gas, SiF ₄ gas and silicon nitride using a N ₂ gas fluoride The films 2 and 3 are sequentially deposited on the substrate 1 to produce the insulating film 10.

The substrate 1 is Mo / glass in which Mo is formed on glass. The film thickness of Mo is 100 nm and the thickness of the glass is 0.5 mm.

Furthermore, the substrate temperature was 150 占 폚, the pressure at the time of film formation was 2.6 Pa, and the high frequency power was 1.1 W / cm2.

Referring to FIG. 8, in the case of manufacturing the insulating film 10 using the manufacturing method 2, the gas introducing portion 26 of the plasma apparatus 100 can supply 500 sccm of N ₂ gas in vacuum To the container (20).

The vacuum evacuation apparatus sets the pressure in the vacuum chamber 20 to 2.6 Pa. Further, the heater 34 sets the temperature of the substrate 1 at 150 占 폚.

Then, the high frequency power supply 62 supplies the planar conductor 50 with a high frequency power of 1.1 W / cm 2 through the matching circuit 64, the connecting conductor 68 and the feeding electrode 52.

Accordingly, plasma using N ₂ gas is generated in the vacuum chamber 20, and the substrate 1 is processed by the generated plasma.

The gas introducing section 26 supplies 25 sccm of SiF ₄ gas and 450 sccm of N ₂ gas to the vacuum container 20 from the timing t5 to the timing t6.

As a result, a silicon nitride film 2 having a film thickness of 10 nm is deposited on the substrate 1.

Then, at time t6, the gas admission unit 26 increasing the flow rate of SiF ₄ gas at 25 sccm to 100 sccm, and reducing the flow rate of N ₂ gas in 450 sccm 250 sccm. Thereafter, the gas introducing section 26 supplies 100 sccm of SiF ₄ gas and 250 sccm of N ₂ gas to the vacuum container 20 until timing t7.

As a result, the silicon nitride film 3 having a film thickness of 90 nm is deposited on the silicon nitride film 2.

Then, the gas supply 26, at time t7, and stops the SiF ₄ gas and N ₂ gas.

On the other hand, during the period from the timing t4 to the timing t7, the high-frequency power, the reaction pressure and the substrate temperature are set to the above-mentioned values.

As described above, in the manufacturing method 2, the silicon nitride films 2 and 3 are formed by changing the ratio of the flow rate of the N ₂ gas to the flow rate of the SiF ₄ gas.

The insulating film 10 manufactured by the manufacturing method 2 is formed by applying a voltage to the insulating film 10 in the film thickness direction of the insulating film 10 in the same manner as the insulating film 10 manufactured by the manufacturing method 1, The breakdown field strength and leakage current density were measured.

Fig. 9 is a diagram showing the relationship between the dielectric breakdown field strength and leakage current density and the gas flow rate ratio in the insulating film produced by Production Method 2. Fig.

9, the ordinate indicates the dielectric breakdown field strength and the leakage current density, and the abscissa indicates the ratio of the flow rate of the N ₂ gas to the flow rate of the SiF ₄ gas. The curve k3 shows the relationship between the dielectric breakdown field strength and the gas flow rate, and the curve k4 shows the relationship between the leakage current density and the gas flow rate. The gas flow rate ratio (= N ₂ / SiF ₄ ) was changed by maintaining the flow rate of SiF ₄ gas at 25 sccm and the flow rate of N ₂ gas at 62.5 sccm, 250 sccm and 450 sccm.

9, the dielectric breakdown field strength, gas flow rate ratio (= N ₂ / SiF ₄₎ 10 by the gas flow rate ratio (= N ₂ / SiF ₄₎ therefore increases with the increase of the gas flow rate ratio (= N ₂ / SiF ₄ ) Is 10 or more, it increases finely beyond 7 [MV / cm] (see curve k3).

Then, the gas flow rate of the breakdown field strength of insulation of the (= N ₂ / SiF _4), the gas flow rate ratio (= N ₂ / SiF ₄₎ is large to 10, gas flow rate ratio (= N ₂ / SiF ₄₎ is 10 or more , It becomes smaller. Accordingly, the gas flow rate of the breakdown field strength of insulation of the (= N ₂ / SiF ₄₎ is a gas flow rate ratio _{(= N 2 / SiF 4)} = to 10 to the boundary there is clearly changed, gas flow rate ratio (= N ₂ / SiF ₄ ) = 10 is the critical point.

In addition, the leakage current density, gas flow rate ratio (= N ₂ / SiF ₄₎ 10 by the gas flow rate ratio (= N ₂ / SiF ₄₎ decreases with the increase of the gas flow rate ratio (= N ₂ / SiF ₄₎ is 10 or more If a is the ^{1 × 10 -6 [a / ㎠} ] or less (refer to curve k4).

And, the gas flow rate of decrease of the leakage current density of the (= N ₂ / SiF _4), the gas flow rate ratio (= N ₂ / SiF ₄₎ large and is up to 10, gas flow rate ratio (= N ₂ / SiF ₄₎ is 10 or more , It becomes smaller. Accordingly, the gas flow rate of decrease of the leakage current density of the (= N ₂ / SiF ₄₎ is a gas flow rate ratio _{(= N 2 / SiF 4)} = to 10 to the boundary there is clearly changed, gas flow rate ratio (= N ₂ / SiF ₄ ) = 10 is the critical point.

As described above, the dielectric breakdown field intensity increases with an increase in the gas flow rate ratio (= N ₂ / SiF ₄ ) with the gas flow rate ratio (= N ₂ / SiF ₄ ) = 10 as the critical point, = N ₂ / SiF ₄ ) = 10 as a critical point and decreases as the gas flow rate ratio (= N ₂ / SiF ₄ ) increases.

When the gas flow rate ratio (= N ₂ / SiF ₄ ) is 10 or more, the dielectric breakdown field intensity is 7 MV / cm and the leakage current density is 1 × 10 ^-6 [A / cm 2] An insulating film (silicon nitride film 2 / silicon nitride film 3) with good insulating performance can be produced. This is because oxygen atoms are not emitted from the glass due to the F radicals in the plasma and the oxygen atoms are hardly received by the silicon nitride films 2 and 3 because the glass substrate 1 covered with Mo is used .

Therefore, in order to produce an insulating film (silicon nitride film) having a small leakage current density and a high dielectric breakdown field strength by the manufacturing method 2, the gas flow rate ratio (= N ₂ / SiF ₄ )

Thus, the production method 2, by the ratio (= N ₂ gas / SiF ₄ gas), the flow rate of N ₂ gas to the flow rate of SiF ₄ gas N ₂ gas / SiF set to ₄ gas = 250/25 = 10 or more silicon the flow rate of N ₂ gas to the flow rate of the nitride, and forming the film (2), SiF ₄ gas ratio (= N ₂ gas / SiF ₄ gas), the N ₂ gas / SiF set to ₄ gas = 250/100 = 2.5 So that the silicon nitride film 3 is formed.

When the SiF ₄ gas is used as the main gas and the N ₂ gas is used as the auxiliary gas, the silicon nitride film 2 is set such that the ratio of the flow rate of the sub-gas to the flow rate of the main gas is equal to or greater than the reference value (= 10) And the silicon nitride film 3 is formed by setting the ratio of the flow rate of the secondary gas to the flow rate of the main gas at a value (= 2.5) smaller than the reference value (= 10).

As described above, in the production method 2, the silicon nitride film 2 is formed by setting the gas flow rate ratio (= N ₂ / SiF ₄ ) equal to or higher than the reference value, and the silicon nitride film 3 is formed with the gas flow rate ratio ₂ / SiF ₄ ) is set to a value smaller than the reference value. As a result, the F radical in the plasma becomes larger on film formation side of the silicon nitride film 3 than on the film formation side of the silicon nitride film 2. Therefore, the fluorine concentration of the silicon nitride film 3 becomes higher than the fluorine concentration of the silicon nitride film 2.

In addition, since the surface of the substrate 1 is covered with metal, the F radical in the plasma at the time of forming the silicon nitride films 2 and 3 does not release oxygen atoms from the substrate 1 , The oxygen atoms are not received in the silicon nitride films 2, 3. Therefore, as described above, the insulating film 10 manufactured by the manufacturing method 2 has good insulation performance.

On the other hand, in the above-described production method 2, the plasma treatment using N ₂ gas may be omitted.

10 is a process diagram showing Manufacturing Method 2. 10, when the production of the insulating film 10 is started, the ratio of the flow rate of the N ₂ gas to the flow rate of the SiF ₄ gas is set to be not less than a reference value, and the silicon nitride film 2 (Step S11).

Then, the silicon nitride film 3 is formed on the silicon nitride film 2 by setting the ratio of the flow rate of the N ₂ gas to the flow rate of the SiF ₄ gas to a value smaller than the reference value (step S 12).

Thus, the production of the insulating film 10 using the manufacturing method 2 is completed.

<< Manufacturing Method 3 >>

11 is a timing chart of the gas flow rate in the manufacturing method 3 of the insulating film 10 shown in Fig.

In the manufacturing method 3 of the insulating film 10, the silicon nitride film 2 is deposited on the substrate 1 by using a SiF ₄ gas, a gas containing an oxygen atom or a hydrogen atom, and an N ₂ gas, The silicon nitride film 3 is deposited on the silicon nitride film ₂ by using SiF ₄ gas and N ₂ gas to produce the insulating film 10.

The substrate 1 is an IGZO / SiN _x / silicon wafer in which SiN _x and a-IGZO are sequentially deposited on a silicon wafer. The film thickness of a-IGZO is 100 nm, the thickness of SiN _x is 100 nm, and the thickness of a silicon wafer is 0.55 mm.

Furthermore, the substrate temperature was 150 占 폚, the pressure at the time of film formation was 2.6 Pa, and the high frequency power was 1.1 W / cm2.

In the case of manufacturing the insulating film 10 using the manufacturing method 3, the gas introducing portion 26 of the plasma apparatus 100 has a flow rate of 25 sccm of SiF ₄ gas and 450 sccm of N ₂ gas And 100 sccm of N ₂ O gas are supplied to the vacuum chamber 20.

The vacuum evacuation apparatus sets the pressure in the vacuum chamber 20 to 2.6 Pa. Further, the heater 34 sets the temperature of the substrate 1 at 150 占 폚.

Then, the high frequency power supply 62 supplies the planar conductor 50 with a high frequency power of 1.1 W / cm 2 through the matching circuit 64, the connecting conductor 68 and the feeding electrode 52.

As a result, a plasma is generated in the vacuum chamber 20, and a silicon nitride film 2 having a film thickness of 50 nm is deposited on the substrate 1. [

At the timing t2, the gas introducing section 26 increases the flow rate of the SiF ₄ gas from 25 sccm to 100 sccm, reduces the flow rate of the N ₂ gas from 450 sccm to 250 sccm, stops the N ₂ O gas . Thereafter, the gas introducing section 26 supplies 100 sccm of SiF ₄ gas and 250 sccm of N ₂ gas to the vacuum container 20 until timing t3.

As a result, the silicon nitride film 3 having a film thickness of 50 nm is deposited on the silicon nitride film 2.

Then, the gas supply 26, at time t3, and stops the SiF ₄ gas and N ₂ gas.

On the other hand, during the period from the timing t1 to the timing t3, the high-frequency power, the reaction pressure, and the substrate temperature are set to the above-described values.

Thus, in the manufacturing method 3, the silicon nitride film 2 disposed in contact with the substrate 1 (= IGZO / SiN _x / silicon wafer) is a main gas for forming the silicon nitride film 2 A film is formed by adding N ₂ O gas to the SiF ₄ gas, and the silicon nitride film 3 is formed without adding N ₂ O gas to the SiF ₄ gas.

As a result, since the O radicals generated from the N ₂ O gas are present in the plasma at the time of forming the silicon nitride film 2, the F radicals in the plasma are emitted from the substrate 1 (= IGZO / SiN _x / It is inhibited from releasing oxygen atoms from a-IGZO in the silicon wafer). That is, even if the F radical releases an oxygen atom from a-IGZO, the oxygen atom is supplemented into the a-IGZO by the O radical in the plasma.

Therefore, the oxygen atoms in the substrate 1 (= IGZO / SiN _x / silicon wafer) are hardly received by the silicon nitride film 2.

Further, the fluorine concentration of the silicon nitride film 3 becomes higher than the fluorine concentration of the silicon nitride film 2 by the mechanism described in Production Method 2.

12 is a diagram showing a method of measuring the electrical characteristics of the insulating film manufactured by the manufacturing method 3. Fig.

Referring to FIG. 12, a silicon nitride film is deposited on a-IGZO of IGZO / SiN _x / silicon wafer by Production Method 3.

Connect the power and ammeter in series between the other two points of a-IGZO.

The power supply changes the voltage value and applies the voltage between two other points of a-IGZO. Then, the ammeter measures the leakage current flowing on the surface of the a-IGZO.

Fig. 13 is a diagram showing the relationship between the leakage current and the gas flow rate in the insulating film manufactured by Manufacturing Method 3. Fig.

13, the vertical axis represents leakage current, and the horizontal axis represents the ratio of the flow rate of N ₂ O gas to the flow rate of SiF ₄ gas. The curve k5 shows the relationship between the leakage current and the gas flow rate. Further, the gas flow rate ratio (= N ₂ O / SiF ₄ ) is a ratio of the flow rate of SiF ₄ gas and N ₂ The flow rate of the gas was maintained at 25 sccm and 450 sccm, respectively, and the flow rate of the N ₂ O gas was changed to 0 sccm, 25 sccm, 50 sccm and 100 sccm.

13, the leakage current density, gas flow rate ratio _{(= N 2 O / SiF 4} ) is 2 through the gas flow rate ratio _{(= N 2 O / SiF 4} ) increases with decreases, and gas flow rate ratio in (= N ₂ O / SiF ₄ ) becomes 2 or more, it becomes 1 × 10 ^-11 to 1 × 10 ^-10 [A] (see curve k5).

Then, the gas flow rate ratio is reduction of the leakage current for the _{(= N 2 O / SiF 4} ) , the gas flow rate ratio _{(= N 2 O / SiF 4} ) are two by two large, the gas flow rate ratio _{(= N 2 O / SiF 4} ) Or less. Accordingly, the gas flow rate ratio is reduction of the leakage current for the _{(= N 2 O / SiF 4} ), the gas flow rate ratio _{(= N 2 O / SiF 4} ) = 2 I a is obviously changed in a boundary, the gas flow rate ratio (= N ₂ O / SiF ₄ ) = 2 is a critical point.

Thus, the leakage current decreases with an increase in the gas flow rate ratio (= N ₂ O / SiF ₄ ) with the gas flow rate ratio (= N ₂ O / SiF ₄ ) = 2 as the critical point.

When the gas flow rate ratio (= N ₂ O / SiF ₄ ) is 2 or more, the leakage current is 1 × 10 ^-11 to 1 × 10 ^-10 [A], and the increase in resistance at the interface with a- (Silicon nitride film 2 / silicon nitride film 3) can be produced. This is because oxygen atoms in the a-IGZO in the substrate 1 (= IGZO / SiN _x / silicon wafer) are hardly released by the O radical in the plasma when the silicon nitride film 2 is formed, This makes it difficult for the oxygen atoms to be received in the silicon nitride film 2.

Therefore, in order to produce an insulating film (silicon nitride film) having a small leakage current by Manufacturing Method 3, the gas flow rate ratio (= N ₂ O / SiF ₄ ) may be 2 or more.

As described above, the SiF ₄ gas flow rate and the N ₂ gas flow rate were maintained at 25 sccm and 450 sccm, respectively, and the N ₂ O gas flow rate was changed to 0 sccm, 25 sccm, 50 sccm, and 100 sccm, (= N ₂ O / SiF ₄ ) is changed so that the ratio of the total flow rate of the N ₂ gas and the N ₂ O gas to the flow rate of the SiF ₄ gas when the gas flow rate ratio (= N ₂ O / SiF ₄ ) (= (N ₂ gas + N ₂ O gas) / SiF ₄ gas) becomes (N ₂ gas + N ₂ O gas) / SiF ₄ gas = (450 + 50) / 25 = 20 or more.

Thus, the production method 3,, N ₂ gas and the N of the total flow rate of ₂ O gas ratio (= (N ₂ gas + N ₂ O gas) / SiF ₄ gas) for the flow rate of SiF ₄ gas (N ₂ gas + N ₂ O gas) / SiF ₄ gas = (450 + 50) / 25 = 20 or more, and the ratio of the flow rate of N ₂ gas to the flow rate of SiF ₄ gas (= N ₂ gas / SiF ₄ gas) was set to N ₂ gas / SiF ₄ gas = 250/100 = 2.5 to form the silicon nitride film 3.

Therefore, when the SiF ₄ gas is used as the main gas and the N ₂ gas and the N ₂ O gas are used as the additive gas, the silicon nitride film 2 has a ratio of the flow rate of the negative gas to the flow rate of the main gas, 20), and the silicon nitride film 3 is formed by setting the ratio of the flow rate of the secondary gas to the flow rate of the main gas to a value (= 2.5) smaller than the reference value (= 20).

On the other hand, in the production method 3, the silicon nitride film 2 may be formed by using any of oxygen (O ₂ ) gas, H ₂ gas and NH ₃ gas instead of N ₂ O gas, The silicon nitride film 2 may be formed using a gas containing oxygen atoms.

14 is a process diagram showing Manufacturing Method 3. 14, when the production of the insulating film 10 is started, the ratio of the total flow rate of the hydrogen atoms or the gas containing oxygen atoms and the N ₂ gas to the flow rate of the SiF ₄ gas is set to be not less than a reference value, The silicon nitride film 2 is formed on the substrate (step S21).

Then, the silicon nitride film 3 is formed on the silicon nitride film 2 by setting the ratio of the flow rate of the N ₂ gas to the flow rate of the SiF ₄ gas to a value smaller than the reference value (step S22).

Thus, the production of the insulating film 10 using the manufacturing method 3 is completed.

Although SiF ₄ gas is used as a main gas for forming the silicon nitride films 2 and 3 in the above-described manufacturing methods 1 to 3, the present invention is not limited to this, and a silicon nitride film 2 and 3 may be formed of a gas containing fluorine atoms and silicon atoms.

In Production Method 1, SiF ₄ gas is used as the main gas, and a gas containing hydrogen atoms and N ₂ gas are used as negative gases to set the ratio of the flow rate of the sub-gas to the flow rate of the main gas And the ratio of the flow rate of the sub-gas to the flow rate of the main gas is set to a value smaller than the reference value by using SiF ₄ gas as the main gas and using N ₂ gas as the sub-gas Thereby forming a silicon nitride film 3.

In Production Method 2, SiF ₄ gas is used as the main gas, and the ratio of the flow rate of the sub-gas to the flow rate of the main gas is set to be equal to or higher than the reference value by using N ₂ gas as the negative gas to form the silicon nitride film 2 And the ratio of the flow rate of the secondary gas to the flow rate of the main gas is set to a value smaller than the reference value by using SiF ₄ gas as the main gas and using N ₂ gas as the negative gas to form the silicon nitride film 3 ).

In Production Method 3, SiF ₄ gas is used as the main gas, and a gas containing hydrogen atoms or oxygen atoms and N ₂ gas are used as the negative gas to adjust the ratio of the flow rate of the sub- Or more, and the ratio of the flow rate of the sub-gas to the flow rate of the main gas is set to be smaller than the reference value by using the SiF ₄ gas as the main gas and using the N ₂ gas as the sub- The silicon nitride film 3 was formed.

Therefore, the manufacturing method of the insulating film 10 according to the embodiment of the first invention may be any of the manufacturing methods shown in Fig.

15 is a process diagram showing a manufacturing method of the insulating film 10 according to the embodiment of the first invention.

Referring to FIG. 15, when the production of the insulating film 10 is started, the gas flow ratio of the subgas comprising the silicon gas and the fluorine atom and the main gas consisting of at least nitrogen gas is set to be equal to or higher than a reference value, A first silicon nitride film is formed (step S31). Then, the gas flow rate ratio of the main gas and the nitrogen gas is set to a value smaller than the reference value, and the second silicon nitride film is formed in contact with the first silicon nitride film (step S32).

Thus, the production of the insulating film 10 is completed.

The insulating film 10 manufactured by the above-described manufacturing methods 1 to 3 has a structure in which the fluorine concentration of the silicon nitride film 3 is larger than the fluorine concentration of the silicon nitride film 2. That is, the fluorine concentration of the silicon nitride film 2 is less than the fluorine concentration of the silicon nitride film 3. This is because, as described above, the concentration of the F radical in the plasma at the time of forming the silicon nitride film 2 is made lower than the concentration of the F radical in the plasma at the time of forming the silicon nitride film 3, This is because the nitride film 2 is formed.

In addition, when the amount of the F radical in the plasma is reduced, the release of the oxygen atoms from the substrate 1 is inhibited, and the oxygen atoms are inhibited from being absorbed into the silicon nitride films 2, 3. As a result, the insulating film 10 having a high dielectric breakdown field strength and a small leakage current can be produced.

Therefore, if the fluorine concentration in the silicon nitride film on the substrate 1 side is lower than the fluorine concentration in the silicon nitride film on the surface side of the insulating film 10 in the manufactured insulating film 10, ) Is less, and good insulation performance can be obtained.

&Lt; Embodiments 2 to 4 >

Hereinafter, on the basis of the drawings, semiconductor devices according to the second to fourth embodiments of the second invention of the present invention will be described. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

The semiconductor device of the second invention is a semiconductor device comprising an oxide semiconductor layer containing at least an indium (In) atom and an oxygen (O) atom and an insulating film containing a silicon (Si) atom, a fluorine (F) . The inventors of the present invention have found that a change in Vth can be suppressed when a semiconductor element made of a TFT has the oxide semiconductor layer and the insulating film in contact with the oxide semiconductor layer. Although the reason is not clear, for example, the following is considered as one of the reasons.

That is, it is known that in the oxide semiconductor layer containing In and O, the O content, the H content, the N content, and the chemical bonding state thereof affect the semiconductor characteristics. When the insulating film in contact with the oxide semiconductor layer contains Si, F, and N, the influence on the contents of O, H, and N, and the chemical bonding state in the oxide semiconductor layer is small, It is possible to suppress the influence on the semiconductor characteristics of the oxide semiconductor layer resulting from the change of the Vth of the TFT. On the other hand, the inventors of the present invention have also found that it is important that F exists in the insulating film by various examinations repeatedly.

Hereinafter, in order to describe the second invention more specifically, an example of the embodiment according to the second invention will be described in detail in the second to fourth embodiments by using a semiconductor element made of a TFT.

&Lt; Embodiment 2 >

As a second embodiment, a TFT having characteristics of a composition of a semiconductor layer and a composition of a gate insulating film will be described.

«Semiconductor device»

16 is a schematic sectional view of an example of a semiconductor element. 16, a TFT as a semiconductor element has a structure in which a gate electrode 202, a gate insulating film 203, and a semiconductor layer 204 as a channel layer are sequentially stacked on a substrate 201, and the semiconductor layer 204 A source electrode 205 and a drain electrode 206 are stacked. A passivation film 207 is laminated in the semiconductor layer 204 between the source electrode 205 and the drain electrode 206 and not covered with the both electrodes. The TFT in Fig. 16 is a so-called bottom gate type transistor, and can be suitably used as a switching element for a liquid crystal display device, for example.

As the substrate 201, an insulating substrate such as a plastic film or a glass substrate can be used. Each of the gate electrode 202, the source electrode 205, and the drain electrode 206 may be made of a metal such as Ti, Mo, or Al. Further, it may have a structure in which layers made of respective metals are laminated. Passivation film 207, a silicon (Si) atom, a fluorine (F) atoms and nitrogen (N) may even a reactor made of an insulating film such as silicon oxide (SiO _2), silicon nitride (SiN), yttrium oxide (Y ₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), hafnium oxide (Hf ₂ O ₂ ), titanium oxide (TiO ₂ ), or the like may be used.

In the semiconductor device according to the second aspect of the present invention, by making the composition of the semiconductor layer 204 and the composition of the gate insulating film 203 different from each other, a change in Vth of the semiconductor device can be suppressed. Hereinafter, the semiconductor layer 204 and the gate insulating film 203 will be described in detail.

(Semiconductor layer)

The semiconductor layer 204 is composed of an oxide semiconductor layer containing In and O. More specifically, the semiconductor layer 204 is preferably made of any one of In-Ga-Zn-O, In-Al-Mg-O, In-Al-Zn-O and In-Hf-Zn-O. On the other hand, the base material of "In-Ga-Zn-O" means an oxide semiconductor containing In, Ga, Zn and O as main components, .

When the material of the semiconductor layer 204 is In-Ga-Zn-O, the ratio of the content of In to the total amount of In, Ga and Zn contained in the semiconductor layer 204 (In / (Ga + Zn + In) of not less than 35 atomic% can suppress the change of Vth. Further, by setting the ratio of the content of In to 38 atomic% or more and 43 atomic% or less, it is possible to further suppress the change in Vth. It is preferable that the content of O in the semiconductor layer 204 is 60 atomic% or more and 66 atomic% or less. On the other hand, as a method of quantifying each element in the semiconductor layer 204, Rutherford back scattering method and ICP mass spectrometry method can be used.

The semiconductor layer 204 may be formed of at least one of nitrogen (N), aluminum (Al), silicon (Si), titanium (Ti), vanadium (V), chromium (Cr), zirconium (Zr), niobium It is preferable to further include at least one additional element selected from the group consisting of molybdenum (Mo), hafnium (Hf), tantalum (Ta), tungsten (W), tin (Sn), and bismuth (Bi) It is preferable to increase the ON current flowing between the electrodes. On the contrary, if the concentration of the additive element 0.01 × 10 ²² atm / cc or less, the source-low and tends to increase the ON current flowing between the drain effectively, if it exceeds 10 × 10 ²¹ atm / cc, the source-to drain The flowing OFF current tends to increase. Therefore, it is preferable that the concentration of the additive element in the semiconductor layer 204 is 0.1 × 10 ²¹ atm / cc or less than 10 × 10 ²¹ atm / cc. On the other hand, the concentration (atm / cc) of the added element in the semiconductor layer 204 can be measured by, for example, a secondary ion mass spectrometry (SIMS) method.

The ratio of the oxygen amount A in the semiconductor layer 204 near the interface between the semiconductor layer 204 and the gate insulating film 203 described later to the oxygen amount B in the semiconductor layer 204 other than the vicinity of the interface / B) is greater than 0.78, preferably less than 1. This will be described with reference to FIG.

17 is a schematic enlarged view of area A in Fig. 17, the oxygen amount A of the semiconductor layer 204 located in the region 204a near the interface 220 in contact with the gate insulating film 203 in the semiconductor layer 204 (A / B) of the oxygen amount B of the semiconductor layer 204 located in the portion other than the vicinity of the interface, that is, the portion other than the region 204a, is preferably greater than 0.78 and less than 1. [ In this case, the ON current flowing between the source and the drain of the TFT can be increased.

On the other hand, when the ratio (A / B) is 0.78, it is found that the OFF current flowing between the source and drain tends to become excessively large. Therefore, the ratio (A / B) is preferably 0.8 or more and less than 1, and more preferably 0.8 or more and 0.98 or less, from the viewpoint of stabilizing the characteristics of the TFT under more suitable conditions.

Here, the term "tangential interface" refers to the ion count number of ions attributable to F in the gate insulating film 203 and the ion count number of ions attributable to In in the semiconductor layer 204 in the gate insulating film 203 in the secondary ion mass spectrometry Quot; near the interface &quot; means a region 204a having a thickness of 0.1 nm or more and 20 nm or less from the &quot; interface to be touched &quot;. The oxygen amount A and the oxygen amount B are counts of oxygen ions by secondary ion mass analysis at arbitrary positions of the semiconductor layer 204, respectively.

On the other hand, if the ratio of the oxygen amount A to the oxygen amount B (A / B) in at least a part of the area 204a is within the above range, the above effect can be exhibited. That is, for example, the ratio (A / B) of the oxygen amount A to the oxygen amount B in the region between 0.1 nm and 5 nm from the interface 220 in the region 204a of the semiconductor layer 204 is within the above range. Also, it is sufficient to satisfy the above ratio (A / B) in at least a part of the region 204a near the interface. 17, the oxygen amount A and the oxygen amount B in at least a part (for example, the central part of the area 204a) of the area 204a extending in the left-right direction in the figure are the same as the ratio A / Range.

(Gate insulating film)

In Embodiment 2, the gate insulating film 203 includes Si, F, and N. In the TFT, the semiconductor layer 204 is made of an oxide semiconductor layer containing In and O, and the gate insulating film 203 includes Si, F and N, so that the change of Vth can be suppressed. As a method of quantifying each element in the gate insulating film 203, an energy dispersive fluorescent X-ray analysis (EDX) method of a scanning electron microscope (SEM) band, a transmission electron microscope (TEM) A fluorescence X-ray analysis (EDX) method or the like can be used. It is also possible to use other known techniques used for qualitative analysis of the element.

In the case where F is not included in the gate insulating film 203, the amount of change in Vth can not be reduced. When the content of F is more than 30 at%, the mechanical strength of the gate insulating film 203 is low, Peeling from the substrate occurred. Therefore, the content of F in the gate insulating film 203 is preferably greater than 0 atomic% and not greater than 30 atomic%. Further, the content of F is more preferably 3 atomic% or more, and still more preferably 5 atomic% or more. In particular, when the content of F is 10 atomic% or more and 28 atomic% or less, the Vth variation amount can be more effectively reduced. On the other hand, the content of Si is preferably 25 atomic% or more and 35 atomic% or less, and the content of N is preferably 25 atomic% or more and 40 atomic% or less.

Further, the gate insulating film 203 may further include H. When the gate insulating film 203 contains H, an effect of increasing Ion (on current) is expected. If the content of H in the gate insulating film 203 is larger than 7 atomic%, the amount of change in Vth tends to increase. Therefore, the content of H is preferably 7 atomic% or less. From the viewpoint of further suppressing the change of the Vth characteristic, it is more preferable to be 5 atom% or less. On the other hand, as a method of quantifying H in the gate insulating film 203, for example, secondary ion mass spectrometry can be used. Specifically, a standard sample in which the content of H is already known is prepared, and the number of secondary ion counts per second is compared with a standard sample to enable determination of H in the sample to be measured. In addition, the content of H can be quantified by using the rutherford back scattering method and the elastic semispherical particle detection method.

In addition, the gate insulating film 203 may further include O. When the gate insulating film 203 contains O, an effect of increasing Ion is expected. When the content of O in the gate insulating film 203 is 25 atomic% or more, the amount of Vth variation tends to increase. Therefore, the content of O is preferably less than 25 atomic%, more preferably 20 atomic% or less. On the other hand, as a method for quantifying O atoms in the gate insulating film 203, a Rutherford back scattering method, a secondary ion mass spectrometry method, or the like can be used.

&Lt; Semiconductor device manufacturing method &gt;

Next, a method of manufacturing the TFT of Fig. 16 will be described with reference to Figs. 18 (a) to 18 (d).

(Formation of gate electrode)

18A, a substrate 201 made of a glass substrate is prepared and a gate electrode 202 is formed on the surface 201a of the substrate 201 by, for example, DC sputtering .

(Formation of gate insulating film)

18 (b), a gate insulating film 203 is formed so as to cover the surface 201a of the substrate 201 and the gate electrode 202. Then, as shown in Fig. In the present embodiment, the gate insulating film 203 includes Si, F, and N. [ As a method for forming such a gate insulating film 203, for example, a plasma CVD method can be used. In particular, the plasma CVD method using an internal antenna type ICP plasma source can be suitably used.

Specifically, a substrate 201 on which a gate electrode 202 is formed is placed in a vacuum chamber of a plasma apparatus, vacuum exhaust is performed in a vacuum chamber, and a source gas such as SiF ₄ and N ₂ is introduced into the vacuum chamber . Then, the gate insulating film 203 including Si, F, and N can be formed by activating the source gas using the plasma source.

In the plasma CVD method, the content ratio of each of Si, F and N in the gate insulating film 203 can be adjusted by controlling the mixing ratio of the source gas. In addition, H can be included in the gate insulating film 203 by mixing H ₂ gas, for example, H ₂ gas, into the source gas, and a gas containing O, for example, O ₂ gas, O can be included in the gate insulating film 203.

(Formation of semiconductor layer)

18 (c), a semiconductor layer 204 as a channel layer is formed on a part of the gate insulating film 203. Then, as shown in Fig. In this embodiment, the semiconductor layer 204 includes In and O. For example, a DC (direct current) magnetron sputtering method may be used for forming the semiconductor layer 204.

Specifically, first, as a target, a target made of a conductive oxide sintered body to be a raw material of an oxide semiconductor is prepared. For example, in the case of forming the semiconductor layer 204 made of In-Ga-Zn-O, it is preferable to use a target containing ZnGa ₂ O ₄ crystal in order to further reduce the Vth variation. Subsequently, the target and the substrate 201 are disposed at predetermined positions in the device, and the semiconductor layer is formed on the gate insulating film 203 by sputtering the target by the DC magnetron sputtering method.

Subsequently, the obtained semiconductor layer is coated with a resist on the semiconductor layer, exposed, and developed so as to obtain a predetermined channel width and channel length, thereby forming a resist of a predetermined shape. Then, the substrate 201 on which the resist having the predetermined shape is formed is immersed in the etching aqueous solution to etch the exposed semiconductor layer, thereby forming a semiconductor layer (not shown) on the gate insulating film 203, A layer 204 is formed.

Here, in the case where the semiconductor layer 204 further includes N as an additive element, for example, N ₂ gas is mixed into the gas to be introduced into the sputtering apparatus when the target is sputtered and the mixing ratio thereof is controlled, The concentration of N in the semiconductor layer 204 can be adjusted. In addition, a metal such as aluminum (Al), silicon (Si), titanium (Ti), vanadium (V), chromium (Cr), zirconium (Zr), niobium (Nb), molybdenum (Mo), hafnium ), Tungsten (W), tin (Sn), and bismuth (Bi), these elements may be contained in advance in the target.

17, the ratio (A / B) of the oxygen amount A in at least a part of the region 204a to the oxygen amount B in the region other than the region 204a in the semiconductor layer 204, The mixing ratio of the O ₂ gas to be introduced into the sputtering apparatus when the region 204a near the interface 220 in the semiconductor layer 204 is formed may be adjusted.

(Formation of source electrode and drain electrode)

18 (d), a source electrode 205 and a drain electrode 206 are formed on the semiconductor layer 204 and the gate insulating film 203 by DC sputtering, for example.

More specifically, first, a resist is coated on the semiconductor layer 204, exposed and developed, and then, on the semiconductor layer 204 on which no resist is formed and on the gate insulating film 203 by DC sputtering, A source electrode 205 and a drain electrode 206 are formed. Then, the resist on the semiconductor layer 204 is peeled off to form the substrate 201 on which the source electrode 205 and the drain electrode 206 are formed, as shown in Fig. 18 (d).

(Formation of passivation film)

16, a passivation film 207 is formed on the semiconductor layer 204 exposed from the source electrode 205 and the drain electrode 206. Then, as shown in Fig. For example, a DC magnetron sputtering method can be used to form the passivation film 207. [

According to the second embodiment described above in detail, the semiconductor layer 204 is made of an oxide semiconductor layer containing In and O, and the gate insulating film 203 is made of an insulating film containing Si, F and N. According to the TFT having this structure, it is possible to suppress a change in Vth when the voltage between the gate and the source or the voltage between the source and the drain is used at 20 V or more. As a result, the characteristics of the TFT can be stabilized.

&Lt; Embodiment 3 >

As a third embodiment, a TFT having characteristics in the composition of the semiconductor layer and the composition of the passivation film will be described.

«Semiconductor device»

The TFT of the third embodiment has the structure shown in Fig. Since the structure of the third embodiment other than the semiconductor layer 204, the gate insulating film 203 and the passivation film 207 is the same as that of the second embodiment, the description thereof will not be repeated.

In the embodiment 3, the gate insulating film 203 is Si, F, and may even insulating film containing N, for example, silicon oxide (SiOH), silicon nitride (SiNH), yttrium oxide (Y ₂ O ₃₎ , Aluminum oxide (Al ₂ O ₃ ), hafnium oxide (Hf ₂ O ₂ ), titanium oxide (TiO ₂ ), or the like can be used. Hereinafter, the semiconductor layer 204 and the passivation film 207 will be described in detail.

(Semiconductor layer)

The semiconductor layer 204 is composed of an oxide semiconductor layer containing In and O. More specifically, the semiconductor layer 204 is preferably made of any one of In-Ga-Zn-O, In-Al-Mg-O, In-Al-Zn-O and In-Hf-Zn-O.

The ratio of the oxygen amount C in the semiconductor layer 204 near the interface between the semiconductor layer 204 and the passivation film 207 described later to the oxygen amount D in the semiconductor layer 204 other than the vicinity of the interface, / D) is 1.05 or more and 1.3 or less. This will be described with reference to FIG.

19 is a schematic enlarged view of area B of Fig. 19, the oxygen amount C of the semiconductor layer 204 located in the region 204b near the interface 240 in contact with the passivation film 207 in the semiconductor layer 204 (C / D) of the oxygen amount D of the semiconductor layer 204 located in the semiconductor layer other than the vicinity of the interface, that is, the portion other than the region 204b is 1.05 or more. In this case, the OFF current flowing between the source and the drain of the TFT can be reduced. When the ratio (C / D) exceeds 1.3, the ON current flowing between the source and the drain tends to be excessively low. Therefore, the ratio (C / D) is preferably 1.3 or less.

Here, the term "tangential interface" means the ion count number of ions attributable to F in the passivation film 207 and the ion count number of ions attributable to In in the semiconductor layer 204 in the passivation film 207 in the secondary ion mass spectrometry Quot; near the interface &quot; means a region 204b having a thickness of 0.1 nm or more and 20 nm or less from the &quot; interface to be touched &quot;. The oxygen amount C and the oxygen amount D are count numbers of oxygen ions by secondary ion mass analysis at arbitrary positions of the semiconductor layer 204, respectively.

On the other hand, if the ratio (C / D) of the oxygen amount C to the oxygen amount D in at least a part of the region 204b is within the above range, the above effect can be exhibited. The reason why the ratio (C / D) is satisfied in part is the same as in the second embodiment.

On the other hand, since the composition of the semiconductor layer 204 other than the above is the same as that of the second embodiment, the description thereof will not be repeated.

(Passivation film)

In Embodiment 3, the passivation film 207 includes Si, F, and N. [ In the TFT, the semiconductor layer 204 is made of an oxide semiconductor layer containing In and O, and the passivation film 207 includes Si, F and N, thereby suppressing a change in Vth.

The composition of the passivation film 207 is the same as that of the gate insulating film 203 of the second embodiment. That is, the content of F in the passivation film 207 is preferably larger than 0 atomic% and 30 atomic% or less, more preferably 3 atomic% or more, and still more preferably 5 atomic% or more. In particular, when the content of F is 10 atomic% or more and 28 atomic% or less, the Vth variation amount can be more effectively reduced. When the passivation film 207 further includes H, the content of H is preferably 7 atomic% or less, more preferably 5 atomic% or less. When the passivation film 207 further contains O, the content of O is preferably less than 25 atomic%, more preferably not more than 15 atomic%.

&Lt; Semiconductor device manufacturing method &gt;

The same method as the manufacturing method of the second embodiment can be used for the TFT manufacturing method in the third embodiment. Specifically, in the formation of the passivation film 207 in the third embodiment, a method of forming the gate insulating film 203 in the second embodiment can be used. On the other hand, the gate insulating film 203 in the third embodiment can be formed by a conventionally used method.

The semiconductor layer 204 may be formed by a method of forming the semiconductor layer 204 in the second embodiment. However, when the semiconductor layer 204 is formed so as to satisfy the ratio C / D, the oxygen amount in the sputtering apparatus when the semiconductor layer 204 is formed in the vicinity of the interface with the passivation film 207 is It is necessary to form the semiconductor layer 204 satisfying the above ratio (C / D).

According to Embodiment 3 described in detail above, the semiconductor layer is made of an oxide semiconductor layer containing In and O, and the passivation film is made of an insulating film containing Si, F and N. According to the TFT having this structure, it is possible to suppress a change in Vth when the voltage between the gate and the source or the voltage between the source and the drain is used at 20 V or more. As a result, the characteristics of the TFT can be stabilized.

&Lt; Fourth Embodiment >

As a fourth embodiment, a TFT having characteristics in the composition of the semiconductor layer, the composition of the gate insulating film, and the composition of the passivation film will be described.

The TFT of the fourth embodiment has the structure shown in Fig. In the fourth embodiment, the semiconductor layer 204 is made of an oxide semiconductor layer containing In and O, and both the gate insulating film 203 and the passivation film 207 include Si, F and N. That is, in the fourth embodiment, the gate insulating film 203 has the same composition as the gate insulating film 203 in the second embodiment, and the passivation film 207 is the same as the passivation film 207 in the third embodiment Composition.

In this case also, it is possible to suppress the change in Vth when the voltage between the gate and the source or the voltage between the source and the drain is used as ± 20 V or more, as in the second and third embodiments. Therefore, as a result, the characteristics of the TFT can be stabilized. 17) and a region 204b (see FIG. 18) in the vicinity of the interface in contact with the passivation film 207, which are in contact with the gate insulating film 203, OFF current and / or ON current can be designed to an appropriate value by satisfying the above-described ratio (A / B and C / D) in the second and third embodiments in at least one of the regions, The characteristics can be further stabilized.

Example

In the following various examples and comparative examples according to the second invention, the bottom gate type TFT shown in Fig. 16 was produced.

&Lt; Examples 1-10 >

&Lt; Formation of gate electrode &

First, in each of Examples 1 to 10, a substrate 201 made of alkali-free glass of 25 mm x 25 mm x 0.5 mm was prepared. In addition, a target made of Al and a target made of Mo serving as a raw material of the gate electrode were prepared. On the other hand, each target was processed so as to have a shape of 3 inches (76.2 mm) in diameter and 5.0 mm in thickness. Each target was placed in a target holder in a sputtering apparatus so that the surface of each target having a diameter of 3 inches became a sputter surface, and the substrate was placed in the substrate holder in the sputtering apparatus. At this time, the distance between the target and the substrate was 100 mm.

Subsequently, while the inside of the sputtering apparatus was evacuated to about 1 x 10 &lt; ^-4 &gt; Pa, Ar gas was introduced into the apparatus with the shutters interposed between the substrate and the target to set the pressure in the apparatus to 0.5 Pa, W was applied and sputtering discharge was performed to perform pre-sputtering of each target surface for 10 minutes.

Subsequently, DC sputtering was performed in the order of a target made of Mo, a target made of Al, and a target made of Mo, and a metal layer having a three-layer structure of Mo layer / Al layer / Mo layer was formed on the surface of the substrate. On the other hand, the film thickness of the Mo layer was 20 nm and the film thickness of the gate electrode of the three-layer structure was 100 nm. Then, a photoresist was coated on the metal layer, the electrode wiring pattern was exposed and developed, and then dry etching was performed to form a gate electrode having a desired wiring pattern.

&Lt; Formation of gate insulating film &

Then, a gate insulating film was formed on the exposed surface of the substrate and the surface of the gate electrode. In Example 1, a substrate having a gate electrode formed therein was placed in a vacuum chamber of a plasma apparatus, and vacuum evacuation was performed until the pressure in the vacuum chamber reached 10 ^-5 Pa or less. Subsequently, SiF ₄ and N ₂ were introduced into the vacuum chamber as the source gas, and the pressure in this vacuum chamber was set to 0.5 Pa. Then, the substrate 201 was heated to 150 DEG C, and the source gas was activated by an internal antenna type ICP plasma source to form a gate insulating film made of Si, F and N.

In Examples 2 to 4, a gate insulating film made of Si, F, N and H was formed by further introducing H ₂ gas in addition to SiF ₄ and N ₂ as source gases. In Examples 5 to 10, a gate insulating film made of Si, F, N, H, and O was formed by further introducing H ₂ gas and O ₂ gas in addition to SiF ₄ and N ₂ as source gases.

Further, in each of Examples 1-10, the content of each element in the gate insulating film is different, F is the ratio (SiF ₄ / N ₂₎ of the SiF ₄ and N ₂ in the raw material gas 1/1 to 1 / 20, so that the content in the gate insulating film of each example was adjusted. The content of O in the gate insulating film of each example was adjusted by adjusting the ratio of O ₂ to N ₂ (O ₂ / N ₂ ) in the source gas in the range of 0 to 1/10. The content of H in the gate insulating film of each example was adjusted by adjusting the ratio of the ratio of H ₂ to N ₂ (H ₂ / N ₂ ) in the source gas in the range of 0 to 1/50 .

&Lt; Formation of semiconductor layer &

Subsequently, in each of Examples 1 to 10, a semiconductor layer was formed on the gate insulating film. Specifically, first, a conductive oxide sintered body to be a raw material of each semiconductor layer was prepared as a target. Meanwhile, the target was processed so as to have a shape of 3 inches (76.2 mm) in diameter and 5.0 mm in thickness. A target was placed in a target holder in a sputtering apparatus so that a 3-inch diameter face of the target was a sputter face, and a substrate on which a gate insulating film was formed was placed in a water-cooled substrate holder in the sputtering apparatus. At this time, the distance between the target and the substrate was 40 mm.

Subsequently, while the inside of the sputtering apparatus was evacuated to about 1 x 10 &lt; ^-4 &gt; Pa, Ar gas was introduced into the apparatus with a shutter between the substrate and the target to set the pressure in the apparatus to 1 Pa, W was applied and sputtering discharge was performed to perform pre-sputtering of each target surface for 10 minutes.

Thereafter, a mixed gas having a volume of Ar gas and a volume of O ₂ gas of 93 (Ar): 7 (O ₂ ) was introduced into the apparatus to set the pressure in the apparatus to 0.8 Pa, and a sputter DC By applying electric power, a semiconductor layer made of an oxide semiconductor layer with a thickness of 70 nm was formed on the gate insulating film. On the other hand, the substrate holder was only water-cooled and no bias voltage was applied.

In each of the examples, the conductive oxide sintered body used as the target was a polycrystal. The targets used in Examples 1, 2, 5, and 6 were mixed at an original consumption of In: Ga: Zn = 2: 2: 1 and included a ZnGa ₂ O ₄ crystal phase in addition to an In ₂ Ga ₂ ZnO ₇ crystal phase there was. In addition, the targets used in Examples 3, 4 and 7 were mixed with the original consumption of In: Ga: Zn = 2: 2: 1 and only the In ₂ Ga ₂ ZnO ₇ crystal phase was formed.

In addition, the target used in Example 8 was mixed at a source consumption of In: Al: Zn = 2: 2: 1 and contained a ZnAl ₂ O ₄ crystal phase in addition to an In ₂ Al ₂ ZnO ₇ crystal phase. In addition, the target used in Example 9 was mixed at a source consumption of In: Al: Mg = 2: 2: 1 and contained a MgAl ₂ O ₄ crystal phase in addition to an In ₂ Al ₂ MgO ₇ crystal phase. Further, the target used in Example 10 was In: Hf: Zn = 1: 1: and a mixture in ratios of 1, InHfZnO was composed of _four crystal phase.

Then, after the formed semiconductor layer was annealed in air at 150 캜 for one hour, resist of a predetermined shape was coated on the semiconductor layer, exposed and developed to process the semiconductor layer into a predetermined channel width and channel length. Then, this substrate was immersed in an etching aqueous solution adjusted to a ratio of phosphoric acid: acetic acid: water = 4: 4: 100, thereby etching the semiconductor layer so as to have a predetermined channel width and channel length. On the other hand, the channel width was 20 mu m and the channel length was 10 mu m. Thus, a semiconductor layer made of the constituent elements shown in Table 1 was formed in each example.

&Lt; Formation of source electrode and drain electrode &

Then, after the annealing process, the resist was coated on the semiconductor layer and the gate insulating film, exposed and developed on the semiconductor layer and on the gate insulating film so that only the portion where the source electrode and the drain electrode were formed was exposed. Next, a metal layer made of Mo, a metal layer made of Al, and a metal layer made of Mo are formed in this order on the portion where the resist is not formed (electrode forming portion) by sputtering to form the Mo layer / Al layer / Mo layer A source electrode and a drain electrode each having a three-layer structure were formed. On the other hand, the film thickness of each three-layer structure was 100 nm. Thereafter, the resist was peeled off. Then, this substrate was annealed in nitrogen at 150 占 폚 for 1 hour.

&Lt; Formation of passivation film &

Then, a passivation film was formed on the exposed semiconductor layer. The passivation film forming methods in Examples 1 to 10 were performed in the same manner as the gate insulating film forming method in each example. Therefore, in each of Examples 1 to 10, the composition of the gate insulating film and the composition of the passivation film became equal.

The thickness of the passivation film in each example was set to 500 nm. After forming the passivation film, the structure was subjected to an annealing treatment at 150 캜 for 2 hours in a nitrogen atmosphere to complete the TFT.

 &Lt; Examples 11 to 16 >

&Lt; Formation of gate insulating film &

In Examples 11 to 16, a gate insulating film made of Si, F, N, H, and O was formed by further introducing H ₂ gas and O ₂ gas in addition to SiF ₄ and N ₂ as source gases.

&Lt; Formation of semiconductor layer &

In Examples 1 to 10, the mixing ratio of the Ar gas and the O ₂ gas in forming the semiconductor layer was made constant. In Examples 11 to 13, when the semiconductor layer in the vicinity of the interface where the gate insulating film and the semiconductor layer are in contact is formed , And the ratio of the volume of the Ar gas to the volume of the O ₂ gas was controlled within the range of 100 (Ar): 0 (O ₂ ) to 95: 5. Thus, in Examples 11 to 13, the number of counts A of oxygen ions in the vicinity of the interface in the semiconductor layer at a predetermined position in the secondary ion mass analysis and the number of oxygen ions in the vicinity of the interface in contact with the gate insulating film and the semiconductor layer The ratio (A / B) of the number of counts of oxygen ions B in the secondary ion mass spectrometry in the semiconductor layer was 0.78 to 0.98.

In Examples 14 to 16, the ratio of the volume of the Ar gas to the volume of the O ₂ gas was 90 (Ar): 10 (O ₂ ) to 70 (Ar) when the semiconductor layer near the interface where the semiconductor layer and the passivation film contacted was formed. : 30 &lt; / RTI &gt; Thus, in Examples 14 to 16, the number of counts C of oxygen ions in the vicinity of the interface in the semiconductor layer at the predetermined position in the secondary ion mass spectrometry in the vicinity of the interface where the passivation film and the semiconductor layer are in contact with each other, (C / D) of the number of counts D of oxygen ions in the secondary ion mass spectrometry in the semiconductor layer was 1.05 to 1.35. On the other hand, the thickness of the semiconductor layer to be the &quot; semiconductor layer in the vicinity of the interface &quot; in each of Examples 11 to 16 is shown as &quot; thickness of the interface layer &quot;

In addition, the targets used in Examples 11, 12, 14, and 16 were mixed with an original consumption of In: Ga: Zn = 2: 2: 1 and only the In ₂ Ga ₂ ZnO ₇ crystal phase was formed. On the other hand, the targets used in Examples 13 and 15 were mixed at an original consumption of In: Ga: Zn = 2: 2: 1 and contained a ZnGa ₂ O ₄ crystal phase in addition to an In ₂ Ga ₂ ZnO ₇ crystal phase.

&Lt; Formation of passivation film &

The passivation film forming methods in Examples 11 to 16 were performed in the same manner as the gate insulating film forming methods in each example. Therefore, in each of Examples 11 to 16, the composition of the gate insulating film and the composition of the passivation film became equal.

With respect to the processes other than those described above, TFTs were produced in each of the examples using the same method as in Examples 1 to 10.

&Lt; Examples 17 to 30 &

In Example 17, N ₂ gas was introduced into the sputtering apparatus in addition to the mixed gas consisting of Ar gas and O ₂ gas as a gas at the time of film formation of the semiconductor layer so that an additional element made of N was included in a part of the semiconductor layer did. On the other hand, the flow rate of the N ₂ gas was set at 20% by volume with respect to the total gas flow rate.

In Examples 18 to 30, aluminum (Al), silicon (Si), titanium (Ti), vanadium (V), chromium (Cr), zirconium (Zr), niobium And at least one additive element selected from the group consisting of molybdenum (Mo), hafnium (Hf), tantalum (Ta), tungsten (W), tin (Sn) and bismuth (Bi) Was previously contained to form a semiconductor layer.

Further, in Examples 17 to 30, a target mixed with In: Ga: Zn = 2: 2: 1 as a target for forming a semiconductor layer and a target formed of only In ₂ Ga ₂ ZnO ₇ crystal phase was used did.

Regarding the processes other than those described above, TFTs were produced in each of the examples using the same method as in Examples 1 to 10.

&Lt; Comparative Examples 1 to 4 >

As a comparative example 1, a TFT was fabricated by forming a gate insulating film made of Si, N and H and a passivation film using a parallel plate type plasma CVD apparatus. As Comparative Example 2, a gate insulating film made of Si, O, and H and a passivation film were formed to fabricate a TFT. As Comparative Example 3, a TFT was fabricated by forming a gate insulating film made of Si, O, N and H and a passivation film. As Comparative Example 4, a TFT was fabricated by forming a gate insulating film made of Si and N and a passivation film. On the other hand, the thicknesses of the gate insulating film and the passivation film were 100 nm, respectively.

In addition, the targets used in forming the semiconductor layers in Comparative Examples 1 and 4 were mixed with the original consumption of In: Ga: Zn = 2: 2: 1 and only the In ₂ Ga ₂ ZnO ₇ crystal phase was formed. The targets used in forming the semiconductor layers in Comparative Examples 2 and 3 were mixed at a source consumption of In: Ga: Zn = 2: 2: 1, and in addition to the In ₂ Ga ₂ ZnO ₇ crystal phase, a ZnGa ₂ O ₄ crystal phase .

<Characteristic evaluation of TFT>

With respect to the TFTs manufactured in the above-described manner and each of the comparative examples, the amount of change in Vth was determined as follows. First, a voltage of 20 V is applied between the source electrode and the drain electrode of the TFT, and the voltage (Vgs) applied between the source electrode and the gate electrode is changed from -30 V to 40 V, and the source- (Ids) were measured (measurement 1). A graph is created with the X-axis as Vgs and the Y-axis as √Ids, and a tangent line is drawn with respect to the curve of √Ids-Vgs at the point where d√Ids / dVgs becomes the maximum slope, and the intersection of the tangent line and the X- Respectively. Vgs of this intersection was defined as Vth.

Immediately after measurement 1, a voltage of 20 V was applied between the source electrode and the drain electrode of each TFT, the voltage (Vgs) applied between the source electrode and the gate electrode was set to 40 V, Min. Immediately after the end of the voltage application, a voltage of 20 V was applied between the source electrode and the drain electrode of the TFT as measurement 2 and the voltage (Vgs) applied between the source electrode and the gate electrode was changed from -30 V to 40 V, The current (Ids) between the source and the drain at that time was measured, and Vth was calculated by the method described above.

Then, the difference between Vth in measurement 1 and Vth in measurement 2 is defined as a variation amount of Vth. On the other hand, Ion is defined as Ids when Vgs is 10 V and Ioff is defined as Ids when Vgs is -5 V in the measurement of measurement 1.

Tables 1 to 3 show the composition of each film in each of Examples and Comparative Examples so that the difference in the composition of each film in each of Examples 1 to 30 and Comparative Examples 1 to 4 described above becomes clear. The evaluation results in the respective Examples and Comparative Examples are shown in Tables 4 to 6. &lt; tb &gt; &lt; TABLE &gt;

Referring to Tables 1 to 6, it was found that the semiconductor layer contains In and O, and at least one of the gate insulating film and the passivation film contains Si, F, and N, thereby suppressing the amount of change in Vth of the TFT.

As described above, the embodiments and the examples of the present invention have been described. However, it is originally planned to appropriately combine the configurations of the above-described embodiments and examples.

It is to be understood that the embodiments and examples disclosed herein are illustrative in all respects and not restrictive. It is intended that the scope of the invention be indicated by the appended claims rather than the foregoing description, and that all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.

The present invention is applied to an insulating film and a manufacturing method thereof. Further, the present invention is applied to semiconductor devices.

The present invention relates to a silicon nitride film and a method of manufacturing the same and a method of manufacturing the same. The present invention relates to a plasma processing apparatus and a plasma processing apparatus which are provided with a plasma processing apparatus and a method of manufacturing the plasma processing apparatus. A gate electrode, a gate insulating film, a semiconductor layer, a source electrode, a drain electrode, a drain electrode, and a drain electrode. : Passivation film, 220, 240: interface.

Claims (16)

As an insulating film containing a silicon atom, a fluorine atom and a nitrogen atom,
A first silicon nitride film disposed on a substrate including oxygen atoms,
And a second silicon nitride film disposed in contact with the first silicon nitride film,
Wherein the amount of the fluorine contained in the second silicon nitride film is larger than the amount of the fluorine contained in the first silicon nitride film. A first step of depositing a first silicon nitride film on a substrate containing oxygen atoms by setting a gas flow rate ratio of a main gas containing silicon atoms and fluorine atoms and an auxiliary gas comprising at least nitrogen gas to a reference value or more,
And a second step of depositing a second silicon nitride film in contact with the first silicon nitride film by setting a gas flow rate ratio of the main gas and the nitrogen gas to a value smaller than the reference value. 3. The method of manufacturing an insulating film according to claim 2, wherein the additive is composed of a gas containing hydrogen atoms and a gas containing oxygen atoms and a nitrogen gas. 3. The method for manufacturing an insulating film according to claim 2, wherein the additive is composed of a gas containing hydrogen atoms and a nitrogen gas. 3. The method of claim 2, wherein the surface of the substrate is covered by a metal,
Wherein the vortex comprises only nitrogen gas. An insulating film containing silicon atoms, fluorine atoms and nitrogen atoms,
A semiconductor device comprising an oxide semiconductor layer containing indium atoms and oxygen atoms. The semiconductor device according to claim 6, wherein the oxide semiconductor layer and the insulating film are in contact with each other. The semiconductor device according to claim 6 or 7, wherein the insulating film is at least one of a gate insulating film and a passivation film. The semiconductor device according to any one of claims 6 to 8, wherein the content of the fluorine atoms in the insulating film is greater than 0 atomic% and not greater than 30 atomic%. 10. The semiconductor device according to any one of claims 6 to 9, wherein the insulating film further comprises a hydrogen atom, and the content of hydrogen atoms in the insulating film is more than 0 atomic% and not more than 7 atomic%. 11. The semiconductor device according to any one of claims 6 to 10, wherein the insulating film further comprises oxygen atoms, and the content of oxygen atoms in the insulating film is more than 0 atomic% and less than 25 atomic%. The semiconductor device according to any one of claims 6 to 11, wherein the insulating film is a gate insulating film, and the oxygen amount A in the oxide semiconductor layer in the vicinity of the interface between the gate insulating film and the oxide semiconductor layer, Wherein a ratio (A / B) of the oxygen amount B in the oxide semiconductor layer is greater than 0.78 and less than 1. 13. The semiconductor device according to claim 12, wherein the ratio (A / B) is 0.8 or more and 0.98 or less. The semiconductor device according to any one of claims 6 to 13, wherein the insulating film is a passivation film, and the oxygen amount C in the oxide semiconductor layer in the vicinity of the interface between the passivation film and the oxide semiconductor layer, (C / D) of the oxygen amount D in the semiconductor layer is 1.05 or more and 1.3 or less. 15. The method according to any one of claims 6 to 14, wherein the oxide semiconductor layer is formed of a material selected from the group consisting of nitrogen, aluminum, silicon, titanium, vanadium, chromium, zirconium, niobium, molybdenum, hafnium, tantalum, tungsten, tin and bismuth And further comprising at least one additional element selected from the group consisting of the first element and the second element. 16. The semiconductor device according to any one of claims 6 to 15, wherein the semiconductor element is a thin film transistor.

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