JP3173757B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an insulating substrate made of glass or the like,
Alternatively, a semiconductor device having an insulated gate structure using a non-single-crystal silicon film provided on an insulating film formed over various substrates, for example, a thin film transistor (TFT) or a thin film diode (TFD), or any of those applied. The present invention relates to a thin film integrated circuit, particularly to a thin film integrated circuit for an active liquid crystal display device (liquid crystal display), and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, semiconductor devices having TFTs on an insulating substrate such as glass, for example, active type liquid crystal display devices and image sensors using TFTs for driving pixels have been developed.

In general, a thin film non-single-crystal silicon semiconductor is used for a TFT used in these devices.
An amorphous silicon semiconductor (a-
Si) and those made of polycrystalline or substantially polycrystalline silicon semiconductor having crystallinity. Amorphous silicon semiconductor is most commonly used because it has a low manufacturing temperature, can be relatively easily manufactured by a gas phase method, and has high mass productivity. Since the physical properties are inferior to those of crystalline silicon semiconductors, in order to obtain higher-speed characteristics, it is strongly required to establish a method for manufacturing a TFT made of a polycrystalline silicon semiconductor in the future.

A TFT using amorphous silicon having low mobility
In this case, the characteristics of the gate insulating film did not matter much. For example, in a TFT using amorphous silicon, a silicon nitride film having lower electric characteristics than silicon oxide is used as a gate insulating film. However, in the case of a TFT using a crystalline silicon film having high mobility, the characteristics of the gate insulating film are as important as the characteristics of the silicon film itself. A thermal oxide film is known as a preferable gate insulating film. For example, on a substrate that can withstand high temperatures, such as a quartz substrate, a gate insulating film could be obtained using a thermal oxidation method. (For example, Japanese Patent Publication 3-71793)

[0005] In order to obtain a silicon oxide film sufficient for use as a gate insulating film by a thermal oxidation method, a high temperature of 950 ° C or more was required. However, there is no substrate material other than quartz that can withstand such a high temperature treatment, and there is a problem that the quartz substrate is expensive and has a high melting point, so that it is difficult to increase the area. Further, in a device having a multi-layered semiconductor device such as a TFT, such as a so-called three-dimensional integrated circuit or three-dimensional integrated circuit, the device is required to have a 9
When the temperature becomes higher than 00 ° C., there is a problem that N-type or P-type impurities existing in the lower layer diffuse more than intended. Furthermore, there are difficulties in the apparatus for obtaining a high temperature of 950 ° C. or more, and it has been particularly difficult to satisfy mass productivity.

[0006]

SUMMARY OF THE INVENTION From such a problem,
It has been required that the maximum process temperature be 850 ° C. or less. However, thermal oxidation does not substantially proceed at a temperature of 850 ° C. or less, and therefore, the gate insulating film is formed by a physical vapor deposition (PVD) method such as a sputtering method, or a plasma CVD method or a thermal CVD method. Chemical vapor deposition (CVD)
It had to be manufactured using the method.

However, the insulating film formed by the PVD method or the CVD method has a high dangling bond or a high hydrogen concentration, and has poor interface characteristics. Therefore, it is weak against injection of hot carriers and the like, and charge trapping centers are easily formed due to dangling bonds and hydrogen. For this reason, when it is used as a gate insulating film of a TFT, there is a problem that electric field mobility and a sub-threshold characteristic value (S value) are not good, or a leak current of a gate electrode is large, and a decrease in on-current (deterioration) (Change with time) was severe.

For example, in the case of using a sputtering method which is a PVD method, if a synthetic quartz composed of high-purity oxygen and silicon is used as a target, only a film of a compound of oxygen and silicon is formed in principle. However, it has been extremely difficult to obtain a silicon oxide film in which the ratio of oxygen to silicon in the obtained film is close to the stoichiometric ratio and the number of dangling bonds is small. For example,
Oxygen was preferred as the sputtering gas. However, oxygen has a small atomic weight, a low sputtering rate (deposition rate), and is unsuitable as a sputtering gas in consideration of mass production.

In an atmosphere of argon or the like, a sufficient film-forming rate was obtained, but the ratio of oxygen to silicon was different from the stoichiometric ratio, and was extremely unsuitable as a gate insulating film. Furthermore, it is difficult to reduce dangling bonds of silicon in any sputtering atmosphere. By performing hydrogen annealing after film formation, dangling bonds of silicon can be converted to Si—H or Si. -OH
It was necessary to stabilize. However, the Si—H and Si—OH bonds are unstable, and are easily broken by accelerated electrons and changed to the original dangling bonds of silicon. Such a weak bond Si-H, S
The presence of i-OH caused the deterioration due to the hot carrier injection described above.

[0010] Similarly, a silicon oxide film produced by the plasma CVD method also contains a large amount of hydrogen in the form of Si-H or Si-OH, which has been a source of the above problem.
In addition, when tetraethoxysilane (TEOS) is used as a relatively easy silicon source, there is a problem that carbon is included in the silicon oxide film. The present invention
It is intended to provide a means for solving the above problem.

[0011]

According to the present invention, first, PV
A silicon oxide film is formed over the island-like crystalline silicon by the D method or the CVD method, and then, a dinitrogen monoxide (N
_By annealing at 600 to 850 ° C., preferably 650 to 800 ° C. in an atmosphere containing ₂ O),
This is to improve the characteristics of the silicon oxide film, particularly the characteristics at the interface with the silicon film. Prior to the annealing step in a dinitrogen monoxide atmosphere, annealing may be performed in a hydrogen atmosphere or an atmosphere of a hydrogen nitride such as ammonia (NH ₃ ) or hydrazine (N ₂ H ₄ ).

In the present invention, for example, a sputtering method is used as the PVD method, and a plasma CVD method is used as the CVD method.
Method, a low pressure CVD method, or an atmospheric pressure CVD method may be used. Other film formation methods can be used. Plasma C
As the VD method and the low pressure CVD method, a method using TEOS as a raw material may be used. TEO by plasma CVD
In order to deposit a silicon oxide film using S and oxygen as raw materials, the substrate temperature is desirably 200 to 500 ° C. Also,
The reaction using TEOS and ozone in the low-pressure CVD method proceeds at a relatively low temperature (for example, 375 ° C. ± 20 ° C.), and a silicon oxide film free from plasma damage can be obtained. Similarly, monosilane (Si
Even if H ₄ ) is reacted with oxygen (O ₂ ) as a main raw material, a silicon oxide film free from plasma damage can be obtained. . Further, of the plasma CVD method, ECR-CVD using discharge under ECR (Electron Cyclotron Resonance) conditions
According to the method, since a plasma damage is small, a better gate insulating film can be formed.

In the present invention, an amorphous silicon film is used as a starting material by a plasma CVD method or the like for forming crystalline silicon to be an active layer. There are roughly two crystallization methods. First, after the amorphous silicon film is formed, thermal annealing is performed at a temperature of 500 to 650 ° C. for an appropriate time to crystallize the film. During the crystallization, an element which promotes crystallization of amorphous silicon, such as nickel, iron, platinum, palladium, and cobalt, may be added. By adding these elements, the crystallization temperature can be lowered and the crystallization time can be shortened.

[0014] Since these elements are the are contained in high concentration impairs the semiconductor characteristics of the silicon, sufficient for crystallization, and no little influence on the semiconductor characteristics, 1 × 10 ¹⁷ to 1
It is preferably contained at a concentration of × 10 ¹⁹ atoms / cm ³ . As a second method, there is a so-called laser annealing method in which an amorphous silicon film is crystallized by irradiating it with strong light such as a laser. Which of the above-mentioned first and second methods should be selected may be determined in consideration of the characteristics of the TFT, the available equipment, the amount of capital investment, and the like required by the one implementing the present invention. .

Further, the first method and the second method may be combined. For example, after crystallization by thermal annealing, a method of further increasing crystallinity by laser annealing may be used. In particular, when thermal annealing was performed by adding a crystallization promoting element such as nickel, it was observed that an amorphous portion was left at a crystal grain boundary or the like. The laser annealing method is effective for the conversion. Conversely, by subjecting a silicon film crystallized by the laser annealing method to thermal annealing, stress distortion of the film caused by laser annealing can be reduced.

[0016]

When a silicon oxide film formed by a CVD method or a PVD method is treated in a dinitrogen monoxide atmosphere at 600 to 850 ° C., Si—H bonds in silicon oxide are nitrided or oxidized, and Si≡N or Si ₂ = changes to NO bond. The Si-OH bond changes as well. In particular, this reaction easily proceeds at the interface between silicon oxide and silicon, and as a result, nitrogen is concentrated at the silicon oxide-silicon interface. The amount of nitrogen that is concentrated and added near the interface by such means becomes 10 times or more the average concentration of the silicon oxide film. It is preferable that the silicon oxide contain 0.1 to 10 atomic%, typically 1 to 5 atomic%, of nitrogen as a gate insulating film.

The same phenomenon cannot be expected in a silicon oxide film obtained by thermal oxidation. That is, since the thermal oxide film is extremely dense, the temperature must be higher than 950 ° C. in order for the oxidizing action by nitrous oxide to proceed. Since a silicon oxide film formed by a CVD method or a PVD method is incomplete compared to a thermal oxide film, the reaction proceeds at a temperature of 850 ° C. or less as described above. As a result of this reaction, even if the film is formed by the CVD method or the PVD method, a dense silicon oxide film is obtained, which is not inferior to the thermal oxide film. (Many of which are derived from unpaired bonds, Si—H bonds, and the like) can be reduced.

It is difficult to nitride and oxidize dangling bonds of silicon by annealing in a dinitrogen monoxide atmosphere. To further promote the reaction, the unpaired bond Si is converted into Si by annealing once at an appropriate temperature in an atmosphere of hydrogen or a hydrogen nitride such as ammonia (NH ₃ ) or hydrazine (N ₂ H ₄ ). It is good to convert to -H bond. The temperature at this time is preferably 350 to 850 ° C. Thereafter, when annealing is performed in an atmosphere of dinitrogen monoxide, a stable bond is obtained by the above-described reaction. Note that, in the treatment in a hydrogen nitride atmosphere, the Si—H bond and the Si さ れ O bond are nitrided, and sometimes Si≡N or Si—N ＝ H ₂ . Such a bond is then converted into an extremely stable Si≡N bond or Si—N ＝ O bond by annealing in a dinitrogen monoxide atmosphere.

A silicon oxide film formed by sputtering the present invention (particularly, a silicon oxide film having an oxygen concentration lower than the stoichiometric ratio by using a sputtering atmosphere of argon or the like).
The effect is particularly remarkable when it is applied to. That is,
This is because annealing of such a film in a dinitrogen monoxide atmosphere makes it possible to compensate for the lack of oxygen and to make the composition of the silicon oxide film close to the stoichiometric ratio. Prior to annealing with dinitrogen monoxide, the silicon oxide film formed by such a sputtering method is heated to an appropriate temperature in an atmosphere of hydrogen or a hydrogen nitride such as ammonia (NH ₃ ) or hydrazine (N ₂ H ₄ ). May be converted into Si—H bonds by annealing. By doing so, oxidation by annealing in a dinitrogen monoxide atmosphere is more likely to proceed.

The above shows that the formation of the silicon oxide film by the sputtering method is not disadvantageous. That is,
Conventionally, to form a silicon oxide film by a sputtering method,
In order to make the composition close to the stoichiometric ratio, it could be performed only in an atmosphere with limited conditions. For example, considering a system of a mixed atmosphere of oxygen and argon as an atmosphere, it is necessary to satisfy the condition of oxygen / argon> 1, and it is desirable to perform the treatment in a pure oxygen atmosphere. Therefore, the film formation rate was low and it was not suitable for mass production. Oxygen is a reactive gas, and there is also a problem that a vacuum device, a chamber, and the like are oxidized.

However, according to the present invention, even a silicon oxide film having a composition different from the stoichiometric composition can be converted into a silicon oxide film suitable for use as a gate insulating film. At
It can be performed under more advantageous conditions with respect to the film formation rate, such as oxygen / argon ≦ 1. For example, the film formation rate is extremely high as in a pure argon atmosphere, and a film can be formed under stable conditions.

According to the present invention, a CVD method such as a plasma CVD method or a low pressure CVD method is performed using a carbon source containing carbon such as TEOS.
When applied to a silicon oxide film formed by a method, a special effect can be obtained. These silicon oxide films contain a large amount of carbon. In particular, carbon present near the interface with the silicon film has caused a deterioration in TFT characteristics. In the present invention, oxidation proceeds by annealing in a dinitrogen monoxide atmosphere. At that time, carbon is also oxidized and released to the outside as carbon dioxide gas, so that the carbon concentration in the film can be reduced. The above was easily confirmed by the following experiment.

In this experiment, a silicon oxide film was formed on a silicon wafer by plasma CVD using TEOS and oxygen as raw materials.
A sample formed at 1200 ° by the method was used. The sample was annealed in a dinitrogen monoxide and nitrogen atmosphere, and the carbon concentration and the nitrogen concentration were examined by secondary ion mass spectrometry. The results are shown in FIGS. Here, FIG. 4 shows the results of annealing in an atmosphere of dinitrogen monoxide, and (A) and (B) are each 500 ° C. /
It is the result about the sample which performed annealing for 2 hours, and the sample which performed annealing at 800 degreeC / 1 hour.
FIG. 5 shows the results of annealing in a nitrogen atmosphere for comparison. FIGS.
It is the result about the sample which performed annealing for 2 hours, and the sample which performed annealing at 800 degreeC / 1 hour.

From this analysis, looking at the sample that was annealed at 800 ° C. in a dinitrogen monoxide atmosphere shown in FIG. 4B, the concentration of carbon at the interface between silicon oxide and silicon was higher than that of the other samples. Compared with the sample, it was reduced by one digit, and it was confirmed that the concentration of nitrogen was also higher. On the other hand, when looking at the data shown in FIGS. 4A and 5, there was a tendency that carbon was accumulated at the interface and the concentration of nitrogen was not so high. Although these three data are not shown here, they are almost the same as those of the sample that has not been annealed. The nitrogen annealing has no effect, and the annealing in an atmosphere of dinitrogen monoxide is 500%.
It was confirmed that there was no effect at a low temperature of about degree. vice versa,
Annealing in a dinitrogen monoxide atmosphere at a high temperature such as 800 ° C. confirmed that the concentration of carbon was reduced and the concentration of nitrogen was increased in the silicon oxide film, particularly at the interface between silicon oxide and silicon. Was done.

When the present invention is applied to an active layer made of a crystalline silicon film crystallized by adding an element which promotes crystallization of an amorphous silicon film such as nickel, cobalt, iron, platinum and palladium. Has a special effect. The crystallinity of the silicon film crystallized by adding such a crystallization promoting element was extremely good, and a very high field-effect mobility was obtained. A good thing was desired. The gate insulating film according to the present invention is suitable. According to the present invention, by annealing in an atmosphere of dinitrogen monoxide,
Amorphous regions remaining in crystal grain boundaries and the like can be crystallized, and the crystallinity can be further improved.

When the present invention is applied to an active layer using a silicon film subjected to laser annealing, the characteristics of the gate insulating film are reduced by the annealing when the present invention is annealed in a dinitrogen monoxide atmosphere. In addition to the effect of improvement, there is also an effect that the strain on the silicon film caused by the laser annealing can be reduced at the same time in the annealing step.

[0027]

【Example】

Embodiment 1 This embodiment is shown in FIG. In this embodiment, an N-channel TFT is formed by using a silicon oxide film formed by a sputtering method as a gate insulating film and performing thermal annealing according to the present invention. First, a silicon oxide film was formed on a substrate 101 (Corning 1733, 100 mm × 100 mm) as a base oxide film 102 by a sputtering method.
A film having a thickness of 00 to 3000 °, for example, 2000 ° was formed. This underlying silicon oxide film 102 is for preventing contamination from the substrate.

Next, an amorphous silicon film was formed by plasma CVD at 100 to 1500 °, for example, 500 °.
Thereafter, a small amount of an element promoting crystallization, such as nickel, iron, platinum, palladium, or cobalt, was added to the amorphous silicon film, followed by annealing to obtain a crystalline silicon film 103. In this example, a nickel acetate solution was dropped on the amorphous silicon film and spin-dried to form a nickel acetate film on the amorphous silicon film. Thereafter, nickel was introduced into the amorphous silicon film by performing thermal annealing at 550 ° C. for 4 hours in a nitrogen atmosphere, and was crystallized. After the above steps, laser annealing may be further performed to improve the crystallinity of the obtained crystalline silicon film. (Fig. 1 (A))

Next, the crystalline silicon film 103 was etched to form an island-like silicon film 104. This island-shaped silicon film 104 is an active layer of the TFT. Then, a silicon oxide film having a thickness of 200 to 1500 Å, for example, 1000 と し て is formed as the gate insulating film 105 so as to cover the island-shaped silicon film 104. In this example, a silicon oxide film was formed by a sputtering method using a synthetic quartz target in an oxygen atmosphere. Argon may be used as the sputtering gas. In this example, the film was formed under the conditions of a gas pressure of 1 Pa, an input power of 350 W, and a substrate temperature of 200 ° C.

After the formation of the gate insulating film 105, the annealing process of the present invention was performed to improve the characteristics of the gate insulating film, particularly the interface between the gate insulating film and the active layer. In this embodiment, in an atmosphere of dinitrogen monoxide, 600
Thermal annealing was performed at 850 ° C. for 0.5 to 6 hours, for example, 630 ° C. for 3 hours. As a result, hydrogen in the silicon oxide film and at the interface with the silicon film was nitrided or oxidized to decrease, and conversely, nitrogen increased. (FIG. 1 (B))

Thereafter, an aluminum (containing 1 wt% Si or 0.1 to 0.3 wt% Sc) film having a thickness of 3000 to 2 μm, for example, 5000 ° is formed by a sputtering method, and is patterned to form a gate. Electrode 1
06 was formed. Next, the substrate was immersed in an ethylene glycol solution of tartaric acid having a pH of about 7 and 1 to 3%, and anodic oxidation was performed using platinum as a cathode and the aluminum gate electrode 106 as an anode. Anodization is initially performed at a constant current of 150
The voltage was increased to V, and the state was maintained for one hour to complete the operation. In this way, an anodic oxide having a thickness of 1500 to 3500 °, for example, 2000 ° was formed. (Fig. 1 (C))

After that, phosphorus was implanted into the island-like silicon film 104 as an impurity in a self-aligned manner by using the gate electrode 106 as a mask by an ion doping method. At this time, the dose amount is 1 × 10 ¹⁴ to 8 × 10 ¹⁵ atoms / cm ² , and the acceleration voltage is 5
0 to 90 kV, for example, a dose of 1 × 10 ¹⁵ atoms / cm
^{2. The} acceleration voltage was 80 kV. As a result, an N-type impurity region (source / drain region) 107 was formed.
(FIG. 1D) Further, the doped impurity region was activated by laser light irradiation. As laser light,
KrF excimer laser (wavelength 248 nm, pulse width 2
0 nsec), and the energy density is 200-40.
0 mJ / cm ² , for example, 250 mJ / cm ² .

Thereafter, a silicon oxide film was formed as an interlayer insulating film 108 over the entire surface by plasma CVD at 3000.degree., And the interlayer insulating film 108 and the gate insulating film 105 were etched to form contact holes in the source / drain regions 107. Further, an aluminum film is formed at a thickness of 5000 ° by a sputtering method, and etching is performed.
The source / drain electrodes 109 were formed, and an N-channel TFT was manufactured. (Fig. 1 (D))

Since the TFT thus formed has excellent resistance to the gate insulating film, it is resistant to deterioration and a TFT having excellent characteristics can be obtained. For example, the drain voltage is set to +1
The voltage was fixed at 4 V, and the gate voltage was varied from -17 to +17 V, and deterioration of TFT characteristics was evaluated. In the field effect mobility μ ₀ obtained by first measuring and the field effect mobility μ ₁₀ obtained by measuring after the above-described voltage application, 1−
Defining (μ ₁₀ / μ ₀ ) as the deterioration rate, the deterioration rate of the TFT obtained in this example was 0.8%. For comparison, the thermal annealing step of the gate insulating film of the present invention was performed at 800 ° C./1
In the case where the annealing treatment was performed for a long time, the deterioration rate was 52.3% even when the other manufacturing conditions were completely the same.

Embodiment 2 FIG. 2 shows this embodiment. This embodiment uses a silicon oxide film formed by a plasma CVD method using TEOS as a source gas as a gate insulating film, performs thermal annealing according to the present invention, and forms a CMOS type TF.
This is an example in which T is formed. First, the substrate 201 (quartz, 10
0 mm × 100 mm) as an underlying oxide film 202
A silicon oxide film having a thickness of 2000 mm was formed by a sputtering method.

Next, an amorphous silicon film was formed to a thickness of 500 ° by a plasma CVD method. Then, as in the first embodiment,
A nickel acetate film is formed on the amorphous silicon film by spin-drying the nickel acetate solution, and then subjected to thermal annealing at 550 ° C. for 4 hours in a nitrogen atmosphere to form the amorphous silicon film. Was introduced and nickel was crystallized. Then, a KrF excimer laser (wavelength: 248 nm) to further improve the crystallinity
Was used to perform laser annealing. The energy density of the laser was suitably from 250 to 350 mJ / cm ² . In this embodiment, it is set to 300 mJ / cm ² . (Figure 2
(A))

Next, the crystalline silicon film 203 was etched to form island-like silicon films 204 and 205. These island-shaped silicon films 204 and 205 form an active layer of the TFT. The gate insulating film 206 is formed to a thickness of 200 to 150 so as to cover the island-shaped silicon films 204 and 205.
A silicon oxide film of 0 °, for example, 1000 ° was formed. In this example, a silicon oxide film was formed by a plasma CVD method using TEOS and oxygen as source gases.
At this time, as the film forming conditions, the gas pressure was 4 Pa, the input power was 150 W, and the substrate temperature was 350 ° C.

After the formation of the gate insulating film, the annealing treatment of the present invention was performed to improve the characteristics of the gate insulating film, particularly the interface between the gate insulating film and the active layer. In this embodiment, first, thermal annealing was performed at 350 ° C. for 2 hours in a hydrogen atmosphere. As a result, unpaired bonds existing in the silicon oxide film could be filled with hydrogen. Next, thermal annealing was performed at 800 ° C. for one hour in a dinitrogen monoxide atmosphere. As a result, hydrogen in the silicon oxide film and at the interface with the silicon film was reduced by nitridation or oxidation. At this time, carbon was contained in the silicon oxide film formed using TEOS as a source gas, and this carbon was also oxidized and released as carbon dioxide gas and decreased. Thus, a silicon oxide film which was preferable as a gate insulating film could be obtained. (FIG. 2 (B))

Thereafter, an aluminum film having a thickness of 6000 ° was formed by a sputtering method, and this was patterned to form gate electrodes 207 and 208. Next, pH ≒
7. The substrate is immersed in an ethylene glycol solution of tartaric acid of 1 to 3%, platinum is used as a cathode, and the aluminum gate electrode 2 is used.
Anodization was performed using 07 and 208 as anodes. The anodic oxidation was first completed by raising the voltage to 150 V at a constant current and maintaining the state for 1 hour. In this way,
A 2000 mm thick anodic oxide was formed. (Figure 2
(C))

Thereafter, impurities were implanted into the island-like silicon films 204 and 205 in a self-aligned manner by using the gate electrodes 207 and 208 as masks by ion doping. First, P
A region where a channel type TFT is to be formed is covered with a photoresist mask 209, and phosphorus is implanted into the N-type impurity region 21.
0 (source / drain region) was formed. At this time, the dose is 1 × 10 ¹⁴ to 8 × 10 ¹⁵ atoms / cm ² , the acceleration voltage is 50 to 90 kV, for example, the dose is 5 × 10 ¹⁴ atoms / cm ² .
cm ² , and the acceleration voltage was 80 kV. (FIG. 2 (D))

Thereafter, boron is implanted by covering a region for forming an N-channel type TFT with a photoresist mask 211 to form a P-type impurity region 212 (source / drain region).
Was formed. At this time, the dose amount is 1 × 10 ¹⁴ to 8 × 10
¹⁵ atoms / cm ² , an acceleration voltage of 40 to 80 kV, for example, a dose of 1 × 10 ¹⁵ atoms / cm ² , and an acceleration voltage of 65 kV
And (FIG. 2 (E))

Further, the doped impurity regions 210 and 212 were activated by laser light irradiation. As a laser beam, a KrF excimer laser (wavelength 248 nm, pulse width 20 nsec) is used,
The energy density was 200 to 400 mJ / cm ² , for example, 250 mJ / cm ² . Thereafter, a silicon oxide film is formed on the entire surface as an interlayer insulating film 213 by plasma CVD.
The interlayer insulating film 213 and the gate insulating film 206 are etched to form a source / drain region 210,
A contact hole was formed in 212. Further, an aluminum film was formed at a thickness of 5000 ° by a sputtering method, etching was performed, and source / drain electrodes 214 were formed. Thus, a CMOS type TFT was manufactured. (Figure 2
(F))

[Embodiment 3] This embodiment is shown in FIG. The present embodiment is an example in which a silicon oxide film formed by an ECR-CVD method is used, and thermal annealing according to the present invention is performed to form a P-channel pixel TFT. First, an underlying oxide film 3 is formed on a quartz substrate 301 (100 mm × 100 mm).
As No. 02, a silicon oxide film was formed at a thickness of 3000 ° by a sputtering method.

Next, an amorphous silicon film was formed to a thickness of 500 ° by a plasma CVD method. Then, as in the first embodiment,
A nickel acetate film is formed on the amorphous silicon film by spin-drying the nickel acetate solution, and then nickel is introduced by performing thermal annealing at 550 ° C. for 4 hours in a nitrogen atmosphere. Crystallized. Thereafter, laser annealing may be performed to improve the crystallinity. (FIG. 3 (A))

Next, the crystalline silicon film 303 was patterned to form an island-like silicon film 304. This island-shaped silicon film 304 is to form an active layer of the TFT later. Then, a silicon oxide film having a thickness of 1000 ° was formed as a gate insulating film so as to cover the island-shaped silicon film. In this embodiment, ECR-CV using monosilane (SiH ₄ ) as a source gas and nitrous oxide as an oxidizing agent is used.
A silicon oxide film was formed by Method D. At this time, in addition to nitrous oxide, oxygen (O ₂ ), nitric oxide (NO), nitrogen dioxide (NO ₂ ), and the like may be used as the oxidizing agent. As the film forming conditions at this time, the substrate was not heated, and the microwave (frequency: 2.45 MHz) input power was 400 W.

After the formation of the gate insulating film, the annealing treatment of the present invention was performed to improve the characteristics of the gate insulating film, particularly the interface between the gate insulating film and the active layer. In this embodiment, first, at 600 ° C. in an ammonia atmosphere,
A time thermal anneal was performed. As a result, unpaired bonds existing in the silicon oxide film could be filled with hydrogen. Also,
The nitridation reaction also proceeded in this annealing step. Thereafter, thermal annealing was performed at 800 ° C. for one hour in a dinitrogen monoxide atmosphere. As a result, hydrogen in the silicon oxide film and at the interface with the silicon film was reduced by nitridation or oxidation. In this way, by performing thermal annealing once in an ammonia atmosphere and then performing thermal annealing in a dinitrogen monoxide atmosphere, dangling bonds in the silicon oxide film can be effectively reduced. As a result, a silicon oxide film having better characteristics could be produced. (FIG. 3 (B))

Thereafter, a polycrystalline silicon film having a thickness of 6000 ° was formed by a low pressure CVD method, and this was patterned to form a gate electrode 306. A small amount of phosphorus was added to the polycrystalline silicon film in order to improve conductivity.
(FIG. 3C) Thereafter, the island-shaped silicon film 30 is formed by ion doping.
4, boron was implanted as an impurity in a self-aligned manner using the gate electrode 306 as a mask. At this time, the dose amount is 1 to 8 ×
10 ¹⁵ atoms / cm ² , an acceleration voltage of 40 to 80 kV, for example, a dose of 5 × 10 ¹⁵ atoms / cm ² , and an acceleration voltage of 65
kV. As a result, a P-type impurity region 307 (source / drain region) was formed. (FIG. 3 (D))

Further, the doped impurity region 307 was activated by laser light irradiation. As the laser light, a KrF excimer laser (wavelength 24
8 nm, a pulse width of 20 nsec), and an energy density of 200 to 400 mJ / cm ² , for example, 250 mJ.
/ Cm ² . Thereafter, a silicon oxide film was formed on the entire surface as an interlayer insulating film 308 by plasma CVD at 3000 .ANG., And the interlayer insulating film 308 and the gate insulating film 305 were etched to form a contact hole in the source region. Further, an aluminum film is formed by sputtering at 50
After the film is formed, the source electrode 3 is etched.
09 was formed. (FIG. 3 (E))

Thereafter, a silicon nitride film was formed as a passivation film 310 to a thickness of 2000 by plasma CVD, and the interlayer insulating film 308 and the gate insulating film 305 were etched to form contact holes. Furthermore, I
A TO film was formed by a sputtering method, and etching was performed to form a pixel electrode 311 to manufacture a pixel TFT. (FIG. 3 (F))

Embodiment 4 This embodiment is shown in FIG. In this embodiment, a P-channel type pixel TFT is formed by using a silicon oxide film formed by a low pressure CVD method and performing thermal annealing according to the present invention. First, the quartz substrate 30
1 (100 mm × 100 mm) as an underlying oxide film 302
As a result, a silicon oxide film having a thickness of 3000 was formed by a sputtering method.

Next, an amorphous silicon film was formed to a thickness of 500 ° by a plasma CVD method. Thereafter, in a nitrogen atmosphere, thermal annealing was performed at 600 ° C. for 12 hours to be crystallized. Thereafter, laser annealing was further performed to improve the crystallinity. The energy density of the laser was suitably from 250 to 350 mJ / cm ² . In this embodiment, it is set to 300 mJ / cm ² . (FIG. 3
(A))

Next, the crystalline silicon film 303 was patterned to form an island-like silicon film 304. This island-shaped silicon film 304 is to form an active layer of the TFT later. Then, a silicon oxide film having a thickness of 1000 ° was formed as a gate insulating film so as to cover the island-shaped silicon film. In this embodiment, a silicon oxide film was formed by a low-pressure CVD method using monosilane (SiH ₄ ) as a source gas and oxygen gas as an oxidizing agent. At this time, in addition to oxygen gas, dinitrogen monoxide (N ₂ O), nitrogen monoxide (NO), nitrogen dioxide (NO ₂ ), and the like may be used as the oxidizing agent. In this embodiment, the pressure is 0.1 to 10 torr.
r, temperature 300-500 ° C., for example, pressure 1.5 torr
r, a film was formed at a temperature of 400 ° C.

After the formation of the gate insulating film, the annealing treatment of the present invention was performed to improve the characteristics of the gate insulating film, particularly the interface between the gate insulating film and the active layer. In the present embodiment, first, at 800 ° C. in an ammonia atmosphere,
A time thermal anneal was performed. As a result, unpaired bonds existing in the silicon oxide film can be filled with hydrogen, and S
The i-H bond, Si-OH bond, etc. could be nitrided. Then, in an atmosphere of nitrous oxide at 800 ° C.
Thermal annealing was performed for one hour. As a result, hydrogen in the silicon oxide film and at the interface with the silicon film was reduced by nitridation or oxidation. In this way, by performing thermal annealing once in an ammonia atmosphere and then performing thermal annealing in a dinitrogen monoxide atmosphere, dangling bonds in the silicon oxide film can be effectively reduced. As a result, a silicon oxide film having better characteristics could be produced. (FIG. 3 (B))

Thereafter, a polycrystalline silicon film having a thickness of 6000 ° was formed by a low pressure CVD method, and this was patterned to form a gate electrode 306. A small amount of phosphorus was added to the polycrystalline silicon film in order to improve conductivity.
(FIG. 3C) Thereafter, the island-shaped silicon film 30 is formed by ion doping.
4, boron was implanted as an impurity in a self-aligned manner using the gate electrode 306 as a mask. At this time, the dose amount is 1 to 8 ×
10 ¹⁵ atoms / cm ² , an acceleration voltage of 40 to 80 kV, for example, a dose of 5 × 10 ¹⁵ atoms / cm ² , and an acceleration voltage of 65
kV. As a result, a P-type impurity region 307 (source / drain region) was formed. (FIG. 3 (D))

Further, thermal annealing was performed at 500 to 650 ° C. for 3 to 24 hours, for example, at 600 ° C. for 12 hours to activate the impurity ions. Thereafter, a silicon oxide film is formed on the entire surface as an interlayer insulating film 308 by plasma CVD.
The interlayer insulating film 308 and the gate insulating film 305 were etched to form a contact hole in the source region. Further, an aluminum film was formed at a thickness of 5000 ° by a sputtering method, and etching was performed to form a source electrode 309. (FIG. 3E) Thereafter, a silicon nitride film was formed as a passivation film 310 by 2000 cm by a plasma CVD method, and the interlayer insulating film 308 and the gate insulating film 305 were etched to form contact holes. Further, an ITO film was formed by a sputtering method, and etching was performed to form a pixel electrode 311 to manufacture a pixel TFT. (FIG. 3
(F))

[0056]

As described above, according to the present invention, the TFT
The characteristics have been greatly improved. In particular, the gate insulating film showed resistance to hot carrier injection, reduced deterioration, and improved reliability. Although the embodiments have been described mainly on TFTs on a glass substrate, it is apparent that excellent effects can be obtained by applying the present invention to a multilayer integrated circuit (also referred to as a three-dimensional integrated circuit or a three-dimensional integrated circuit). is there. Thus, the present invention is an industrially useful invention.

[Brief description of the drawings]

FIG. 1 shows the steps of Example 1.

FIG. 2 shows the steps of Example 2.

FIG. 3 shows the steps of Examples 3 and 4.

FIG. 4 shows SIMS data.

FIG. 5 shows SIMS data.

[Explanation of symbols]

 101, substrate 102, base oxide film 103, crystalline silicon film 104, island-shaped silicon film 105, gate insulating film 106, gate electrode 107 ..Impurity regions (source / drain regions) 108..interlayer insulating films 109..source / drain electrodes

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yasuhiko Takemura 398 Hase, Atsugi-shi, Kanagawa Examiner, Kazuya Tanada, Semiconductor Energy Laboratory Co., Ltd. (56) References JP 5-74763 (JP, A) Hei 7-201846 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 29/786 H01L 21/316 H01L 21/336

Claims (7)

(57) [Claims] 1. A wherein the you annealing in crystalline covering the island-like silicon region by depositing a silicon oxide film by P VD method, following dinitrogen monoxide atmosphere wherein the 850 ° C. 600 ° C. or higher, a silicon oxide film Of manufacturing a semiconductor device. 2. A CVD method covering a crystalline island-like silicon region.
Or PVD by depositing a silicon oxide film, and annealing the silicon oxide film in a hydrogen or a nitride in a hydrogen atmosphere, after the annealing, the silicon oxide film 600 ° C. to 850
A method for manufacturing a semiconductor device , comprising annealing in an atmosphere of dinitrogen monoxide at a temperature of not more than ° C. 3. The method of claim 1 or 2, the method for manufacturing a semiconductor device wherein the silicon oxide film is characterized in that it is deposited by sputtering. 4. The silicon oxide film according to claim 2 , wherein
A method for manufacturing a semiconductor device, wherein the semiconductor device is deposited by a CR-CVD method. 5. The method according to claim 2 , wherein the silicon oxide film is deposited by a CVD method using tetraethoxysilane (TEOS) as a raw material. 6. The method for manufacturing a semiconductor device according to claim 2 , wherein the silicon oxide film is deposited by a low pressure CVD method using monosilane and oxygen as main materials. 7. The silicon oxide film according to claim 1 , wherein
In the island-like silicon region to be deposited , 1 × 10 ¹⁷ to 1 × 10 ¹⁹
A method for manufacturing a semiconductor device, which includes an atom / cm ³ of a crystallization promoting element.