JP2002289613A - Method for forming insulating oxide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming an insulating oxide film with superior electric characteristics, wherein oxidation is prevented from advancing into a substrate during the period of deposition of the oxide film. SOLUTION: The insulating oxide film with superior electric characteristics can be formed by switching oxidizing gases to be supplied or separating gas components under control to prevent oxidation from advancing into a substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an oxide insulating film used as a gate insulating film or a capacitor dielectric film of a semiconductor device.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of integrated circuits (Si-LSI), the gate length of a transistor tends to be less than 0.1 μm. In both directions, it is necessary to realize a finer and sharper impurity profile.
For this reason, the high-temperature process after forming the channel or the S / D requires a reduction in the time and the temperature.

In particular, formation of a gate insulating film at a low temperature is one of the major issues, and high-temperature oxidation, ozone oxidation, plasma / UV-excited radical oxidation, and the like are employed as methods for reducing the oxidation temperature when forming a SiO ₂ film.

On the other hand, a thin film forming method by chemical vapor deposition (CVD) is generally used for materials other than SiO ₂ films such as high dielectric constant films, but few attempts have been made to apply it to SiO ₂ for gate oxide films. Such conventional film forming techniques include:
For example, G. Lukovsky, Extended Ab
structures of SSDM2000, P232,
And its reference, the oxidizing agent is pre-excited and mixed with the main material to give a CVD to the substrate surface.
In this method, a high-quality film having a good stoichiometric composition ratio is formed at a low temperature.

[0005]

Since the conventional method for forming an oxide insulating film is performed as described above, the excited oxidizing agent also oxidizes the substrate side, so that an unintended oxide film is formed during the oxide film deposition. There are problems such as growth of the oxide film, which causes a substrate interface level to be generated, thereby deteriorating the device characteristics, and forming a film having a dielectric constant different from that of the deposited oxide film to cause a decrease in the dielectric constant. Was.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a high quality in which the stoichiometric composition of an oxide film is maintained while preventing the oxidation of the inside of the substrate when the oxide film is deposited on the substrate. It is an object of the present invention to obtain a method for forming an oxide insulating film that enables the formation of a film.

Further, according to the present invention, it is possible to form a transistor having a high driving force or a capacitor having a large storage capacity, thereby improving the characteristics of a memory or the like, miniaturizing and increasing the integration, improving the yield of an integrated circuit and reducing the cost. It is an object of the present invention to obtain a method for forming an oxide insulating film which can achieve reduction.

[0008]

According to a method of forming an oxide insulating film according to the present invention, an oxide film main material gas is reacted with an oxidizing gas which has been activated in advance, and a reaction gas is formed on a substrate of a semiconductor device. In the method of forming an oxide insulating film,
Of the oxidizing gas, an active oxidizing component having a strong osmotic power into the film and having a strong oxidizing power is defined as a component 1, and an active oxidizing component having reactivity with the main material gas of the oxide film but having a low osmotic power into the film Is the component 2, the oxide film main material gas and the oxidizing gas of the component 2 are simultaneously supplied to the substrate for a certain period of time, and the oxide film main material gas reacts with the oxidizing gas and is deposited on the substrate; A film deposition step of forming an oxide thin film on the substrate, a deposition film oxidation step of supplying the oxidizing gas of the component 2 to the substrate for a certain period of time to oxidize the substrate and the oxide thin film on the substrate, A strong oxidation step of supplying an oxidizing gas to the substrate for a certain period of time to oxidize the substrate and an oxide thin film on the substrate; and mixing and supplying the oxidizing gas of the component 1 and the component 2 for a certain period of time to supply the oxidizing gas to the substrate and the substrate. Mixed acids that oxidize oxide thin films A step and a gas supply interruption step of interrupting gas supply for a certain time between the respective steps are provided, and among these steps, a series of steps including at least the film deposition step and the deposited film oxidation step in time series The process is repeated.

A method for forming an oxide insulating film according to the present invention comprises:
A compound containing Si is applied as an oxide film main material gas.

[0010] The method for forming an oxide insulating film according to the present invention comprises:
A compound containing Ta is applied as an oxide film main material gas.

[0011] A method for forming an oxide insulating film according to the present invention comprises:
Al, Hf, Sc, Zr,
Any of Y, Gd, La, Sr, Ti, Ba, Pt,
Alternatively, a compound containing a combination thereof is applied.

A method for forming an oxide insulating film according to the present invention comprises:
A compound containing O ₂ is applied as an oxidizing gas.

A method for forming an oxide insulating film according to the present invention comprises:
A substrate made of a non-oxide semiconductor is used.

[0014] The method for forming an oxide insulating film according to the present invention comprises:
A substrate made of a non-oxide metal is used.

[0015] The method for forming an oxide insulating film according to the present invention comprises:
The oxidizing gas of component 1 is obtained by directly irradiating the substrate with an oxidizing gas that has been activated in advance.

The method for forming an oxide insulating film according to the present invention comprises:
The oxidizing gas of component 2 is obtained by indirectly irradiating the substrate with an oxidizing gas activated in advance.

The method for forming an oxide insulating film according to the present invention comprises:
The type 2 oxidizing gas is obtained by switching and controlling the type of the oxidizing gas applied to the substrate.

The method for forming an oxide insulating film according to the present invention comprises:
The supply flow rate of the oxidizing gas to the substrate is changed to obtain the oxidizing gas of the component 2.

A method for forming an oxide insulating film according to the present invention comprises:
The oxidizing gas of the component 1 is composed of atomic oxygen.

A method for forming an oxide insulating film according to the present invention comprises:
The oxidizing gas of the component 2 is composed of molecular oxygen.

The method for forming an oxide insulating film according to the present invention comprises:
The film deposition step is a step prior to the first deposited film oxidation step.

The method for forming an oxide insulating film according to the present invention comprises:
The substrate temperature during the film formation is set to a low temperature so that the thermal oxidation inside the substrate during one cycle is 1/10 or less of the film thickness deposited on the substrate in the film deposition step.

The method for forming an oxide insulating film according to the present invention comprises:
The gas supply time in each step of the film deposition step and the deposited film oxidation step, or the gas supply cycle time, causes the oxidizing gas component to pass through the oxide film formed on the substrate in the film deposition step and pass on the substrate surface. It is set to be shorter than the time it takes.

The method for forming an oxide insulating film according to the present invention comprises:
The gas supply time in each step of the film deposition step and the deposited film oxidation step, or the gas supply cycle time is made longer according to the number of cycles of the film deposition step and the deposited film oxidation step. is there.

The method for forming an oxide insulating film according to the present invention comprises:
As means for indirectly irradiating the substrate with a previously activated oxidizing gas, a shielding means is arranged between the irradiation source of the oxidizing gas and the substrate with a gap therebetween.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a schematic structural explanatory view showing a plasma CVD apparatus applied to realize a method for forming an oxide insulating film according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a growth chamber (growth chamber) of a plasma CVD apparatus, and 2 denotes a plasma source arranged above the growth chamber 1. This plasma source 2 has an rf coil-wrapped cell arranged in a magnetic field. The configuration uses a helicon plasma cell. Reference numeral 3 denotes a substrate heating lamp (substrate heating source) disposed below the growth chamber 2, and reference numeral 4 denotes a substrate heating lamp disposed on the optical path of the substrate heating lamp 3 and positioned between the substrate heating lamp 3 and the plasma source 2. A substrate 5 on which a film is to be formed is placed on the substrate holder 4.

Reference numeral 6 denotes a thermocouple (temperature measuring means) disposed near the substrate holder 4, and 7 denotes a liquid nitrogen shroud disposed around the substrate holder 4. The impurity gas is trapped during the growth of the oxide film. Reference numeral 8 denotes an ion gauge, 9 denotes a turbo molecular pump for performing main exhaust, and 10 denotes a load lock chamber.

Reference numeral 11 denotes a first gas supply pipe, and reference numeral 12 denotes a second gas supply pipe. These first and second gas supply pipes 11 and 12 are connected to an oxidizing gas (O ₂ ) supply source. The first gas supply pipe 11 has a tip nozzle portion facing the inside of the plasma source 2, and the second gas supply pipe 12 has a downstream side from the branch part of the first gas supply pipe 11. The third and fourth gas supply pipes 13 and 14 are connected on the side,
The third gas supply pipe 13 is provided with an oxide film main material gas (Si
_{2 H 6)} supplying the oxide film main material gas from the supply source, the fourth
The gas supply pipe 14 supplies different types of oxidizing gas or oxide film main material gas.

As described above, the third and fourth gas supply pipes 1
The second gas supply pipe 12 to which the gas supply pipes 3 and 14 are connected is for directly supplying an oxidizing gas, an oxide film main material gas, or a mixed gas thereof to the substrate 5 on the substrate holder 4. 1
Reference numeral 5 denotes a connection pipe for connecting each of the second, third, and fourth gas supply pipes 12, 13, and 14 to the turbomolecular pump 9, and 16 denotes the gas supply pipes 11, 12, 13, 14, and the connection pipes. Valves provided in each of the connection pipes 15, 1
Reference numeral 7 denotes a mass flow controller provided in each of the gas supply pipes 11, 12, 13, and 14, and these mass flow controllers 17 serve as gas flow control means for controlling the gas flow in each system.

Reference numeral 18 denotes a plasma source 2 in the growth chamber.
A first shutter disposed between the plasma source 2 and the substrate 5 on the substrate holder 4. The first shutter 18 is disposed between the outlet of the plasma source 2 and the substrate 5 on the substrate holder 4. And a closing means for opening and closing the closed position. Although the first shutter 18 blocks the space between the outlet of the plasma source 2 and the substrate 5 in the closed position as described above, the first shutter 18 in the closed position includes:
A gap is formed between the outlet of the plasma source 2 and the substrate 5 so that gas can flow. Therefore, the first
By closing the shutter 18 of the plasma source 2
Gas from the system is supplied indirectly to the substrate 5 on the substrate holder 4, and by opening the first shutter 19, gas from the plasma source 2 system is directly supplied to the substrate 5. Things.

Here, the two plasma sources are used to convert the substrate 5
The active oxidizing component of the oxidizing gas differs between the case where the activated oxidizing gas is directly supplied and the case where the oxidizing gas is indirectly supplied. That is, when the first shutter 18 is opened,
Since the oxidizing gas from the two plasma sources is directly supplied to the substrate 5, the oxidizing gas has a strong oxidizing power and a strong oxidizing component (hereinafter referred to as an active oxidizing component) that has a strong penetrating power into a film deposited on the substrate 5.
Component 1). Further, when the first shutter 18 is closed, the oxidizing gas from the two plasma sources is indirectly supplied to the substrate 5, so that the active oxidizing gas has reactivity with the oxide film main material gas. The active oxidizing component (hereinafter, referred to as component 2) has a low penetrating power into the film deposited on the substrate. Therefore, the first shutter 18 also functions as a gas component control unit for controlling the separation of the oxidizing gas supplied from the two plasma sources into components 1 and 2 by opening and closing the first shutter 18.

Reference numeral 19 denotes a second shutter disposed between the substrate 5 on the substrate holder 4 in the growth chamber 1 and the tip end of the second gas supply pipe 12. A closed position for blocking the front side of the substrate 5 on the substrate holder 4 so that the gas from the second gas supply pipe 12 is not supplied onto the substrate 5; It is operated to the open position to be supplied onto the substrate 5.

Next, the operation of the plasma CVD apparatus having the above configuration and a method of forming an oxide insulating film by the apparatus will be described. In the first embodiment, a method for forming an oxide insulating film in the case where SiH ₄ is used as an oxide film main material gas and oxygen is used as an oxidizing gas is described by a plasma CVD method.
This will be described in relation to the operation of the device. In the method for forming an oxide insulating film according to the present invention, as a film deposition step, an oxide film main material gas (SiH ₄ ) and the oxidizing gas of the component 2 are simultaneously supplied to the substrate for a certain period of time to deposit an oxide thin film on the substrate. However, in order to perform the film deposition process, plasma CVD
In the apparatus, the first shutter 18 is closed and the second shutter 19 is opened, and in this state, the oxidizing gas is supplied from the first gas supply pipe 11 and the third gas supply pipe 13 is simultaneously supplied with the oxidizing gas. The oxide film main material gas (SiH ₄ ) is supplied through the second gas supply pipe 12.

At this time, the oxidizing gas supplied from the first gas supply pipe 11 is activated by plasma excitation by the plasma source 2, and the activated oxidizing gas collides with the first shutter 18 and diffuses. As a result, the oxidizing gas becomes an active oxidizing component (component 2) which has a reactivity but has a low penetrating power into a film deposited on the substrate 5.

Then, as described above, within the time during which the oxide film main material gas (SiH ₄ ) and the oxidizing gas are simultaneously supplied,
The oxide film main material gas (SiH ₄ ) reacts with the active oxidizing gas and deposits on the substrate 5. As described above, the active oxidizing gas at this time is mainly composed of an active oxidizing component (component 2) having a low penetration force into the oxide thin film deposited on the substrate 5, and
The active oxidizing component does not oxidize the inside of the substrate 5.

As described above, in the film deposition step, the oxide film main material gas and the component 2 are simultaneously supplied onto the substrate 5 for a certain period of time to thereby supply the oxide film main material gas and the component gas. 2 reacts with the oxidizing gas and the substrate 5
An oxide thin film is formed thereon. After the film deposition step, the simultaneous supply of the oxide film main material gas and the oxidizing gas of the component 2 is interrupted for a certain period of time (gas supply interrupting step). After the elapse of the gas supply interruption time, the process proceeds to the next deposited film oxidation step.

In the deposited film oxidation step, the first shutter 1
By closing the second shutter 19 and keeping the second shutter 19 open, only the active oxidizing gas (oxidizing gas of component 2) is supplied from the first gas supply pipe 11 system to the substrate 5 for a certain period of time. 5 and the oxide thin film on the substrate 5 are oxidized.

Therefore, the thickness of the oxide thin film formed on the substrate 5 in the film deposition step is sufficiently oxidized in the deposited film oxidation step. After the elapse of the supply time of the active oxidizing gas in the deposition film oxidizing step, the supply of the active oxidizing gas is interrupted for a certain period of time, if necessary (gas supply interrupting step). After the elapse of the gas supply interruption time, the process shifts to the next strong oxidation step.

In this strong oxidation step, the first and second shutters 18 and 19 are both opened, and the active oxidizing gas of the component 1 is supplied to the substrate 5 for a certain period of time, and the substrate 5 and the The oxide thin film is oxidized. As a result, the oxide thin film formed on the substrate 5 in the film deposition step is more sufficiently oxidized. This strong oxidation step can be replaced with the following mixed oxidation step.

In the mixed oxidation step, the components 1 and 2 are mixed and supplied to the substrate 5 from the first gas supply pipe 11, whereby the substrate 5 and an oxide thin film on the substrate 5 are mixed with the components 1 and 2. It is more fully oxidized by the mixed gas of the two.

Here, a gas supply step for interrupting the supply of gas for a certain period of time is provided between the above steps as necessary. Then, a series of steps including at least the film deposition step and the deposited film oxidation step among the above-described steps are repeated in a time series, whereby an oxide insulating film having a predetermined thickness on the substrate 5 is formed.

Next, the above-mentioned plasma CVD apparatus is used.
The results of experiments on the method of forming the oxide insulating film are described below.
You. In the experiment, the oxide film main material gas was SiH
₄And oxygen as the oxidizing gas, respectively.
Activated by plasma excitation as described above
The oxidizing gas is used to open and close the first shutter 18 as described above.
Therefore, they were supplied separately as component 1 and component 2. Further details
In other words, the shutter 18 is closed and activated as a film deposition process.
While supplying reactive oxygen at a flow rate of 10 sccm, SiH ₄
Was supplied, and the gas supply time was T1. Also deposited
As a film oxidation step, the shutter 18 is closed and active oxygen
Only at a flow rate of 10 sccm, and the gas supply time is
T2. Further, as the strong oxidation step, the shutter
Open -18 and supply active oxygen at a flow rate of 10 sccm,
The gas supply time was T3. And the gas supply
Times T1, T2, T3 are set in this order for 30 seconds, 10 seconds,
Set 10 seconds (see Fig. 2) and repeat this cycle 50 times.
I returned.

As a result, a 4 nm-thick Si
O ₂ (oxide insulating film) was obtained. As described above, a film deposition step by simultaneous supply of active oxygen and SiH ₄ with the shutter 18 closed, a deposition film oxidation step by supply of only active oxygen with the shutter 18 closed, and a shutter 18 a strong step by supplying active oxygen in the open state as one cycle and a SiO ₂ film formation by repeating this cycle, was comparatively evaluated MOS capacitor with SiO ₂ by conventional gas continuous feed deposition According to the present invention, the interface state density is 1E11 cm,
It has been found that it can be reduced from the middle of 2 eV-1 to 1E10 cm-2 eV-1 or less, and the other CV characteristics are similarly improved. It was also found that the breakdown electric field strength was almost the same as the conventional one.

Further, the cycle number dependence of the oxide film thickness when the above cycle is repeated is shown in FIG. 3, and it can be seen that a film thickness proportional to the cycle number can be obtained. Further, when the gas supply time T1 was changed, as shown in FIG. 4, a film thickness per cycle corresponding to the length of the gas supply time was obtained. Therefore, it is possible to precisely control the film thickness of an arbitrary film thickness by controlling the number of cycles and controlling the supply amount of SiH ₄ per cycle.

Embodiment 2 FIG. 5 shows an embodiment of the present invention.
Per cycle in the method of forming an oxide insulating film according to state 2
5 is a time chart showing the gas supply control time of FIG. this
In the second embodiment, the oxide film main material gas is
SiH used in form 1₄Instead of Si₂H₆Using
Other than the above, an experiment was performed in the same manner as in the first embodiment.
Was. In this experiment, the shutdown of the plasma CVD apparatus of FIG.
The reactor 18 is closed and active oxygen and Si₂H ₆And supply at the same time
Gas supply time T1 of the film deposition process to be performed is 30 seconds, and
A bank that supplies only active oxygen by closing the shutter 18
The gas supply time T2 for the film oxidation step is set to 10 seconds.
And the gas supply time T1 and the gas supply time T1 as shown in FIG.
The gas supply time T2 is alternately repeated to grow the deposited film.
, Si₂H₆Is determined only by the gas supply time T1
A grown film thickness was obtained. Therefore, the gas oxide of T2
It was found that oxidation of the substrate did not progress only with
It was confirmed.

On the other hand, it was confirmed that when the supply of active oxygen was completely stopped during the supply of Si ₂ H ₆ , deposition of SiO ₂ hardly occurred. From this fact, it can be seen that, in order to advance the deposition reaction, the supply of active oxygen is indispensable through the shutter 18 when Si ₂ H _{6 is} supplied.

An experiment in which the plasma CVD apparatus of FIG. 1 is used and the main gas of the oxide film is Si ₂ H ₆ will be specifically described. In this experiment, the plasma CV
In the D apparatus, the main exhaust was performed by the turbo molecular pump 9 and the trapping of the impurity gas was performed by the liquid nitrogen shroud 7 during the film growth. 99.9 not diluted gas system
Using 9% of Si ₂ H ₆ and O ₂ , the flow rate is controlled through the mass flow controller 17, and the pressure in the growth chamber (growth chamber 1) when changing between 0.1 sccm and 10 sccm is 10 −3. It is in the order of 〜１０10−１1 Pa. The frequency of the plasma source 2 is 13.58 MH
The z, rf power is up to 200W. Substrate 5 is made of Si
A (100) wafer was formed into a 17 mm square and transported by a quartz susceptor. The degree of vacuum during film growth is 1 × 10−2 to 2 × 10
-1 Pa.

The radio frequency (RF) power of the plasma cell is set to 0
FIG. 7 shows the result of measuring the oxide film thickness of SiO ₂ after the growth for 60 min when the width was changed from W to 200 W. In the figure, a film thickness of about 2 ° was observed at an RF power of 0 W, but this was measured in the atmosphere, and the formation of a natural oxide film is inevitable.

When the RF power was gradually increased, the oxide film thickness at an oxygen flow rate of 1 sccm increased almost linearly with the increase in the RF power. On the other hand, oxygen flow rate 10sc
The oxide film thickness in cm was only 1/3 to 1/4 as compared with the case where the oxygen flow rate was 1 sccm, and increased gradually to 150 W and then increased rapidly to 200 W. On the other hand, the oxidation rate was not simply proportional to the oxygen flow rate, and it was found that the oxygen flow rate was higher at 1 sccm than at 10 sccm. The cause thereof will be described later, but it is important that the amount of the active species controlling the oxidation is important. Oxygen flow is 1
In both cases of sccm and 10 sccm, since the plasma effect increases with the plasma power, the subsequent experiments were performed at a maximum output of 200 W.

FIG. 8 is a table showing the dependence of the oxide film thickness on the substrate in an experiment. The film thickness after oxidation for 60 minutes is 2 in both cases of the oxygen flow rate of 1 sccm and 10 sccm.
It was found that there was no substrate temperature dependency in the range of 50 to 630 ° C.

FIG. 9 is a table showing the dependence of the oxide film thickness on the oxidation time in an experiment. The thickness of the oxide film rapidly increased within 15 minutes or less, and the oxidation rate thereafter decreased with the extension of the oxidation time, and the film thickness tended to be saturated.

FIG. 10 is a table showing the oxygen dependence of the oxide film thickness after 60 minutes of growth by experiment. Oxygen flow rate 1sc
cm or less, the oxide film thickness increased with an increase in the flow rate, but the oxygen flow rate peaked at 1 sccm and then decreased with the flow rate. It is considered that the decrease after the oxygen flow rate of 1 sccm is a result of loss of active species due to an increase in collision between molecules with an increase in pressure.

As described above, unlike thermal oxidation, in which the reaction at the interface or diffusion of oxygen in the oxide film is rate-limiting, in plasma oxidation, the supply of active species dominant to oxidation is a rate-determining process, and the activation rate is low. Can be concluded to have a flow rate (pressure) dependence.

Next, the result of examining the condition dependency of the film thickness of plasma CVD for introducing Si ₂ H ₆ simultaneously with active oxygen will be described. FIG. 11 is a table showing the dependency of the SiO ₂ film thickness on the deposition time by plasma CVD and plasma oxidation. The thickness of the plasma CVD film formed by growth for 60 minutes or less rapidly rises at the beginning, and thereafter increases with time at a constant gradient. The behavior in a short time reflects the characteristics of the oxidation described above, while the plasma CVD for more than 60 minutes
Then, it is considered that when the oxidation component is saturated, the deposition component becomes dominant.

Therefore, in each growth time, the plasma C
FIG. 12 shows the time dependence of the SiO ₂ film thickness deposition component as a result of subtracting the plasma oxidation film thickness from the VD film thickness.
It can be seen from the figure that the deposition component of the film formation rate is 0.05 nm / min regardless of the oxygen flow rate. That is,
Active species predominant in plasma CVD indicate that deactivation does not occur with increasing pressure. This result is significantly different from plasma oxidation in which oxygen flow rate dependence was observed, and indicates that active species dominant in the oxidation reaction and the deposition reaction are different.

Next, a S film having a plasma CVD film thickness of 60 minutes is formed.
FIG. 13 shows the i ₂ H ₆ flow rate dependency. From the figure, it can be seen that the oxygen flow rates of 1 sccm and 10 sccm both increase with the flow rates at almost the same slope. This means that the active oxygen necessary for the deposition is sufficiently supplied, so that the shortage of the active oxygen does not limit the film forming rate.

According to the second embodiment described above, the supply of active oxygen and the supply of active oxygen through the shutter 18
By repeating a cycle in which active oxygen and Si ₂ H ₆ are simultaneously supplied through the shutter 18 for a predetermined time, the controllability of the film thickness is improved and the electrical characteristics of the film are improved.

Embodiment 3 FIG. The oxide film main material gas is Si
, Compounds containing Ta, Al, H
f, Sc, Zr, Y, Gd, La, Sr, Ti, Ba,
It may be a compound containing any of Pt or a combination thereof. Further, the substrate may be any of a non-oxide semiconductor and metal.

[0059]

As described above, according to the present invention, of the oxidizing gas, the active oxidizing component having a strong osmotic power into the film and having a strong oxidizing power is designated as the component 1, and the reaction with the oxide film main material gas is performed. An active oxidizing component that has a property of weak penetration into the membrane
And the oxidizing film main material gas and the oxidizing gas of the component 2 are simultaneously supplied to the substrate for a certain period of time to cause the oxidizing film main material gas to react with the oxidizing gas and deposit on the substrate. A film deposition step of forming an oxide thin film on the substrate; a deposition film oxidation step of supplying the oxidizing gas of the component 2 to the substrate for a certain period of time to oxidize the substrate and the oxide thin film on the substrate; A strong oxidation step in which the substrate and the oxide thin film on the substrate are oxidized by supplying the substrate and the oxide thin film on the substrate for a certain period of time; A mixed oxidation step of oxidizing, and a gas supply interrupting step of interrupting gas supply for a certain time between the respective steps, wherein at least the film deposition step and the deposited film oxidation step are performed in chronological order. To Since the process is a series of repeated steps, it is possible to prevent oxidation of the inside of the substrate, improve the controllability of the film thickness, eliminate irregularities in transistor characteristics, and improve the yield. This has the effect. Also, the electrical properties of the film are improved,
There is an effect that a high-speed and high-performance transistor can be easily manufactured, and finally, the yield of the integrated circuit can be improved and the cost can be reduced.

According to the present invention, the compound containing Si is used as the oxide film main material gas.
Even when a high dielectric constant insulating film is formed by a compound containing, by suppressing the oxidation of the substrate, a decrease in the dielectric constant is suppressed, and a transistor having a high driving capability and a capacitor having a large storage capacity can be formed. Therefore, there are effects that the characteristics of the memory and the like can be improved, miniaturization and high integration can be achieved, and that the integration of the integrated circuit can be improved and the cost can be reduced.

According to the present invention, the compound containing Ta is used as the oxide film main material gas.
Even when a high dielectric constant insulating film is formed by a compound containing, by suppressing the oxidation of the substrate, a decrease in the dielectric constant is suppressed, and a transistor having a high driving capability and a capacitor having a large storage capacity can be formed. Therefore, there are effects that the characteristics of the memory and the like can be improved, miniaturization and high integration can be achieved, and that the integration of the integrated circuit can be improved and the cost can be reduced.

According to the present invention, as the oxide film main material gas, Al, Hf, Sc, Zr, Y, Gd, La, Sr,
Since a compound containing any one of Ti, Ba, and Pt or a combination thereof is used, it is possible to suppress oxidation of the substrate and a decrease in the dielectric constant during the formation of the high-dielectric-constant insulating film. Transistors and capacitors with large storage capacity can be formed.
This has the effect of improving the characteristics of the memory and the like, miniaturization and high integration, and improving the layout of the integrated circuit and reducing the cost.

According to the present invention, since the compound containing O ₂ is used as the oxidizing gas, there is an effect that the oxide film main material gas can be reacted with the compound to deposit on the substrate.

According to the present invention, since a semiconductor that is not an oxide is used as the substrate material, the effect of preventing oxidation inside the substrate during formation of an oxide film is remarkable.

According to the present invention, since a metal that is not an oxide is used as the substrate material, the effect of preventing oxidation of the inside of the substrate when forming an oxide film is remarkable.

According to the present invention, since the oxidizing gas which has been activated in advance is directly supplied to the substrate, the oxidizing gas directly supplied to the substrate has a strong oxidizing power and a strong oxidizing power. It becomes a component (component 1), which has the effect that the deposited oxide film grown on the substrate can be more sufficiently oxidized without increasing the substrate temperature more than necessary.

According to the present invention, the oxidizing gas which has been activated in advance is indirectly supplied to the substrate, so that the oxidizing gas in this case becomes an active oxidizing component (component 2) having a weak penetrating power into the film. Therefore, there is an effect that oxidation to the inside of the substrate can be prevented.

According to the present invention, there is an effect that the oxidizing gas of the component 2 can be obtained only by switching and controlling the type of the oxidizing gas applied to the substrate.

According to the present invention, there is an effect that the oxidizing gas of the component 2 can be obtained only by changing the supply flow rate of the oxidizing gas to the substrate.

According to the present invention, since the oxidizing gas of the component 1 is converted into atomic oxygen, there is an effect that the oxide film having a predetermined thickness grown on the substrate can be sufficiently oxidized.

According to the present invention, since the oxidizing gas of the component 2 is converted into molecular oxygen, there is an effect that oxidation into the inside of the substrate can be prevented.

According to the present invention, since the film deposition step is performed before the deposition film oxidation step, after depositing the oxide thin film on the substrate in the film deposition step, the deposited oxide thin film is subjected to the next deposition film oxidation step. In this case, it is sufficient to oxidize with the oxidizing gas of the component 2, and therefore, there is an effect that oxidation into the substrate can be prevented.

According to the present invention, the substrate temperature during film formation is
Since the temperature is set low so that the thermal oxidation inside the substrate during one cycle is 1/10 or less of the film thickness deposited on the substrate in the film deposition step, there is an effect that the oxidation inside the substrate can be prevented.

According to the present invention, the gas supply time or the gas supply cycle time in each of the film deposition step and the deposited film oxidation step is reduced by oxidizing the oxide film formed on the substrate in the film deposition step. Since the time is set shorter than the time when the gas component permeates and reaches the substrate surface, there is an effect that oxidation to the inside of the substrate can be prevented.

According to the present invention, the gas supply time in each of the film deposition step and the deposited film oxidation step, or the gas supply cycle time, is reduced by the number of cycles of the film deposition step and the deposited film oxidation step. As a result, the oxide film having a predetermined thickness can be easily grown on the substrate, and the grown oxide film can be sufficiently oxidized. There is an effect that it can be prevented.

According to the present invention, as means for indirectly irradiating the substrate with a previously activated oxidizing gas, a shielding means is provided between the irradiation source of the oxidizing gas and the substrate with a gap therebetween. Since it is arranged, the active oxidizing gas can be easily separated into component 1 and component 2 simply by opening and closing the shielding means.

[Brief description of the drawings]

FIG. 1 is a schematic structural explanatory view of a plasma CVD apparatus applied to a method for forming an oxide insulating film according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a SiH ₄ gas supply cycle when forming an oxide insulating film according to the first embodiment of the present invention.

FIG. 3 is a table showing the cycle number dependence of a deposited film thickness and a deposition rate according to an experiment of the present invention.

FIG. 4 is a table showing the dependency of the supply time of SiO ₂ gas in one cycle when an oxide insulating film is formed according to a second embodiment of the present invention.

FIG. 5 is a cross-sectional view of an oxide insulating film according to a second embodiment of the present invention.
Si during formation ₂H₆Diagram showing the gas supply cycle of
It is.

FIG. 6 is a cross-sectional view of an oxide insulating film according to a second embodiment of the present invention.
Si during formation ₂H₆Diagram showing the gas supply cycle of
It is.

FIG. 7 is a table showing the RF power dependence of the SiO ₂ film thickness in an experiment of the present invention.

FIG. 8 is a table showing the substrate temperature dependence of the SiO ₂ film thickness in an experiment of the present invention.

FIG. 9 is a table showing the dependence of the SiO ₂ film thickness on the film formation time in an experiment of the present invention.

FIG. 10 is a table showing the oxygen dependency of the oxide film thickness after 60 min growth according to the experiment of the present invention.

FIG. 11 is a table showing the dependence of the film thickness of SiO _{2 on} the deposition time by plasma CVD and plasma oxidation in an experiment of the present invention.

FIG. 12 is a table showing the time dependence of the SiO ₂ film thickness deposition component as a result of subtracting the plasma oxidation film thickness from the plasma CVD film thickness.

FIG. 13 is a table showing the dependency of a 60-minute plasma CVD film thickness on the flow rate of Si ₂ H _{6 in} an experiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Growth chamber, 2 Plasma source, 3 Substrate heating lamp, 4 Substrate holder, 5 Substrate, 6 Thermocouple, 7 Liquid nitrogen shroud, 8 Ion gauge, 9 Turbo molecular pump, 10 Load lock chamber, 11-13 Gas supply pipe , 14 connecting pipes, 15 valves, 17 mass flow controller, 18 first shutter, 19 second
Shutter.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kyozo Kanemoto 2-31-19 Shiba, Minato-ku, Tokyo Communication and broadcasting organization (72) Inventor Takashi Yoshida 2-31-19 Shiba, Minato-ku, Tokyo Communication and broadcasting Institution (72) Inventor Tohru Kurabayashi 2-31-19 Shiba, Minato-ku, Tokyo Communication and Broadcasting Corporation (72) Inventor Junichi Nishizawa 2-31-19 Shiba in Minato-ku, Tokyo Communication and Broadcasting Organization F-term (reference 5F058 BA11 BA20 BB05 BB10 BC02 BC03 BF23 BF29 BJ01

Claims (18)

[Claims] 1. A method for forming an oxide insulating film formed on a substrate of a semiconductor device by reacting an oxide film main material gas with a previously activated oxidizing gas, the reaction gas comprising: An active oxidizing component having a strong osmotic power into the inside and a strong oxidizing power is defined as a component 1, and an active oxidizing component having reactivity with the main material gas of the oxide film but weakly penetrating into the film is defined as a component 2. The film main material gas and the oxidizing gas of the component 2 are simultaneously supplied to the substrate for a certain period of time, and the oxide film main material gas reacts with the oxidizing gas to be deposited on the substrate, thereby forming an oxide thin film on the substrate. A film deposition step of forming; a deposition film oxidation step of supplying the oxidizing gas of the component 2 to the substrate for a certain period of time to oxidize the substrate and an oxide thin film on the substrate; Time supply And a strong oxidation step of oxidizing an oxide thin film on the substrate; a mixed oxidation step of mixing the oxidizing gas of the component 1 and the component 2 and supplying the mixed gas for a certain time to oxidize the substrate and the oxide thin film on the substrate; A gas supply interrupting step of interrupting a gas supply for a predetermined time between them, wherein, among these steps, a series of steps including at least the film deposition step and the deposited film oxidation step in time series is repeated. Of forming an oxide insulating film. 2. The method according to claim 1, wherein the oxide film main material gas is a compound containing Si. 3. The method for forming an oxide insulating film according to claim 1, wherein the oxide film main material gas is a compound containing Ta. 4. The oxide film main material gas is Al, Hf, S
2. The method for forming an oxide insulating film according to claim 1, wherein the compound is a compound containing any one of c, Zr, Y, Gd, La, Sr, Ti, Ba, and Pt, or a combination thereof. 5. The method according to claim 1, wherein the oxidizing gas is a compound containing O ₂ . 6. The method according to claim 1, wherein the substrate is made of a non-oxide semiconductor. 7. The method according to claim 1, wherein the substrate is made of a metal other than an oxide. 8. The method for forming an oxide insulating film according to claim 1, wherein the oxidizing gas of the component 1 is obtained by directly irradiating the substrate with an oxidizing gas activated in advance. 9. The method according to claim 1, wherein the oxidizing gas of the component 2 is obtained by indirectly irradiating a substrate with an oxidizing gas activated in advance. 10. The method for forming an oxide insulating film according to claim 1, wherein the oxidizing gas of the component 2 is formed by controlling the type of the oxidizing gas applied to the substrate. 11. The method for forming an oxide insulating film according to claim 1, wherein the oxidizing gas of the component 2 is obtained by changing a supply flow rate of the oxidizing gas to the substrate. 12. The method for forming an oxide insulating film according to claim 1, wherein the oxidizing gas of the component 1 is atomic oxygen. 13. The method for forming an oxide insulating film according to claim 1, wherein the oxidizing gas of the component 2 is molecular oxygen. 14. The method according to claim 1, wherein the film deposition step is a step prior to the deposition film oxidation step. 15. The substrate temperature during film formation is set to a low temperature so that thermal oxidation inside the substrate during one cycle is not more than one tenth of the film thickness deposited on the substrate in the film deposition step. 2. The method for forming an oxide insulating film according to claim 1, wherein: 16. An oxidizing gas component permeates an oxide film formed on a substrate in a film deposition step, or a gas supply time or a gas supply cycle time in each of a film deposition step and a deposited film oxidation step. 15. The method for forming an oxide insulating film according to claim 1, wherein the time is set to be shorter than the time required to reach the substrate surface. 17. The gas supply time in each of the film deposition step and the deposited film oxidation step, or the gas supply cycle time, increases according to the number of cycles of the film deposition step and the deposited film oxidation step. 2. The method according to claim 1, wherein
7. The method for forming an oxide insulating film according to 6. 18. A means for indirectly irradiating a substrate with a previously activated oxidizing gas, wherein a shielding means is provided between the irradiation source of the oxidizing gas and the substrate with a gap therebetween. The method for forming an oxide insulating film according to claim 9, wherein: