JPH0982696A - Manufacture of semiconductor device and semiconductor manufacturing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an insulating film which is less affected by troubles such as film stress and film reduction induced in a condensation CVD method by a method wherein a series of processes composed of a modification process which modifies a condensed film and a condensed film forming process is repeatedly carried out. SOLUTION: A semiconductor substrate 113 is kept at a low temperature, a vapor intermediate is condensed on a semiconductor substrate 113 through the reaction of a film forming gas composed of oxygen radical gas and organic silane gas, whereby a silicon oxide condensed film is formed on the semiconductor substrate 113. Then, nitrogen gas is made flow through the hollow structure of a substrate support 114 as oxygen radical keeps flowing, a tungsten flash lamp 127 and an ultraviolet lamp 128 are turned on (modification process), and the condensed film is thermally treated in an atmosphere of oxygen radical. One cycle of processes composed of a condensed film forming process and a modification process is repeatedly carried out a few times, whereby a silicon film which has a very small impurity content and film reduction and prescribed thickness (thick enough to fill up a groove completely) is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device and a semiconductor manufacturing apparatus characterized by the formation of a silicon oxide film.

[0002]

2. Description of the Related Art In recent years, a large-scale integrated circuit (IC) formed by integrating a large number of transistors, resistors and the like into an important part of a computer or a communication device so as to achieve an electric circuit has been integrated on one chip. LSI) is frequently used. For this reason, the performance of the entire device is greatly related to the performance of the LSI alone.

[0003] The performance of an LSI alone can be improved by increasing the degree of integration, that is, by miniaturizing elements. However, with respect to miniaturization of elements, various process problems are currently occurring.

For example, taking Al alloy wiring as an example, the wiring width and the wiring interval are being miniaturized, but the wiring thickness is being miniaturized only with a gradual tendency. For this reason, when the insulating film is formed so as to cover the Al alloy wiring, the groove between the wirings is not completely filled with the insulating film, and a cavity is generated in the insulating film. This cavity is H
₂ O and the like remain, which causes a problem that the Al alloy wiring corrodes later and corrodes the Al alloy wiring.

On the other hand, in order to increase the degree of integration, the conventional LO
From the element isolation by the COS method, the element isolation by the buried element isolation method has been attempted. This method is
The COS method is an element isolation method that has been devised because there is a limit to the control of bird's beak, and is to dig a groove on the surface of the substrate with good controllability and bury an insulating film in the groove.

However, the conventional buried element isolation method has the following problems. That is, when the aspect ratio of the width of the groove to the depth of the groove, which is an amount representing the steepness of the depth of the groove, becomes high, the groove is not completely filled with the insulating film and the element isolation becomes incomplete. The problem of poor insulation arises. Further, there is a problem that stress is applied to the insulating film filling the groove, and it is difficult to suppress the stress.

There are several methods of forming an insulating film for filling a groove having a high aspect ratio, and one of them is a CVD method utilizing condensation (hereinafter referred to as a condensation CVD method).
The condensation CVD method is, for example, reaction of an organic silane with oxygen radicals or ozone in a gas phase to form a gas phase intermediate, and the gas phase intermediate is formed on the surface of a silicon substrate whose substrate temperature is set to a low temperature. By attaching them, the vapor phase intermediate and the organic silane are condensed on the silicon substrate to form a silicon film. Here, if there is a groove on the surface of the substrate, aggregation is preferentially generated from the bottom of the groove, so that the silicon oxide film can be filled even in the case of a high aspect ratio groove.

However, the conventional condensation CVD method has the following problems. That is, condensation CVD
In the method, since the substrate temperature is set to a low temperature to form a film, in the case of the above example, a large amount of impurities such as C and H existing in the organic silane and the vapor phase intermediate are taken into the silicon oxide film. As a result, there is a problem that the film stress of the silicon oxide film becomes large, or a large volume contraction occurs in the high temperature heat treatment in the subsequent step, resulting in film loss. That is, the conventional condensation CVD method has been regarded as a promising technique for embedding an insulating film in a groove having a high aspect ratio, but it has been revealed that its practical use is difficult.

[0009]

As described above, the conventional condensation CVD method has been regarded as a promising technique for embedding an insulating film in a groove having a high aspect ratio.
It has become clear that its practical application is difficult due to the problem of large film loss.

The present invention has been made in consideration of the above circumstances, and an object thereof is a method of manufacturing a semiconductor layer device capable of forming an insulating film with which the problems of film stress and film loss in the condensation CVD method are improved. And to provide a manufacturing apparatus.

[0011]

[Means for Solving the Problems]

[Outline] In order to achieve the above-mentioned object, a method for manufacturing a semiconductor device according to the present invention (claim 1) sets a semiconductor substrate housed in a processing container to a first substrate temperature, and
An oxygen source gas containing at least one of an oxygen radical gas and a gas that generates oxygen radicals, and a film forming gas consisting of an organic silane gas are introduced, and a gas phase intermediate produced by the reaction of the film forming gas is introduced. A condensation film forming step of forming a condensation film of silicon oxide on the semiconductor substrate by condensing on the semiconductor substrate; and setting the semiconductor substrate to a second substrate temperature higher than the first substrate temperature. A heat treatment of the aggregated film in an atmosphere containing at least one of oxygen radical gas and hydrogen radical gas to modify the aggregated film. And a step of forming a silicon oxide film having a desired film thickness by repeating the series of steps described above a plurality of times.

Further, according to another method of manufacturing a semiconductor device of the present invention (claim 2), in the modification step of the method of manufacturing a semiconductor device (claim 1), a flash lamp having an extinction time constant of a predetermined value or less. Is used to set the semiconductor substrate at the second substrate temperature by irradiating the semiconductor substrate with light from the side where the agglomerated film is formed.

Another semiconductor device manufacturing method according to the present invention (claim 3) comprises at least one of an oxygen radical gas and a hydrogen radical gas in the reforming step of the semiconductor device manufacturing method (claim 1). Is generated by irradiating a gas containing at least one of a gas generating an oxygen radical and a gas generating a hydrogen radical gas with ultraviolet rays using an ultraviolet lamp having an extinction time constant of a predetermined value or less. It is characterized by

A semiconductor manufacturing apparatus according to the present invention (claim 4)
Is a processing container containing a semiconductor substrate, and the inside of the processing container is an oxygen source gas containing at least one of an oxygen radical gas and a gas that generates oxygen radicals, and an organic silane gas. And a gas supply means for supplying a gas containing at least one of an oxygen radical gas and a hydrogen radical gas as an atmosphere gas for heat-treating the aggregate film, and a film forming gas for forming the aggregate film Depressurizing means for depressurizing, a substrate support provided in the processing container, having a hollow structure for mounting the semiconductor substrate, and a gas flowing in the hollow structure of the substrate support, the temperature of the gas A first substrate temperature control means for controlling the temperature of the semiconductor substrate by controlling the semiconductor substrate, and the semiconductor substrate from the side where the aggregation film is formed. And irradiating light to the substrate, characterized in that the quenching time constant for controlling the temperature of said semiconductor substrate and a second substrate temperature control means comprising a predetermined value or less of the flash lamp.

Another semiconductor manufacturing apparatus (Claim 5) according to the present invention is the semiconductor manufacturing apparatus (Claim 4) in which oxygen supplied to the processing container is irradiated with ultraviolet rays to generate oxygen radicals. It is characterized by adding an ultraviolet lamp having an extinction time constant of a predetermined value or less.

According to another semiconductor manufacturing apparatus (Claim 6) of the present invention, in the semiconductor manufacturing apparatus (Claim 4), the gas supply means causes the oxygen-discharged microwave gas to flow through a temperature-controlled trapping tube. It is characterized by

A preferred method of manufacturing the semiconductor manufacturing apparatus and the semiconductor manufacturing apparatus are as follows. In the method for manufacturing a semiconductor device according to the present invention (claim 1), the gas that generates oxygen radicals is one gas selected from O ₃ gas, NO ₂ gas and C0 ₂ gas, or two or more gases. Is preferred.

In the method for manufacturing a semiconductor device according to the present invention (claim 1), the organosilane gas is ethoxysilicate, metooxysilicate, hexamethyldisilicate, or hydrogen atom or hydroxyl group bonded to Si of the main chain. It is preferably a gas of one compound selected from silane polymers or a gas of a mixture of two or more compounds.

In the method of manufacturing a semiconductor device according to the present invention (claim 2 or claim 3), the extinction time constant is 50 ms.
It is preferably ec or less. The thickness of the aggregated film formed at one time is preferably about 10 nm. This is because with such a thickness, impurities (O, H, etc.) in the aggregate film can be effectively removed without lowering the productivity.

From the viewpoint of productivity, the time from the first substrate temperature to the second substrate temperature and the time from the second substrate temperature to the first substrate temperature are preferably 100 msec or less.

The flash lamp is provided with a shielding plate that can be opened and closed within 50 msec, and the extinction time constant is effectively set to 50 m.
It may be set to sec or less. In controlling the temperature of the capturing tube, the oxygen gas subjected to microwave discharge is cooled to the temperature of liquid nitrogen and then warmed in a short time of 10 seconds or less (however, 20 ° C. or less). As a result, the rapidly released gas becomes oxygen radical gas.

It is preferable that the first substrate temperature is -50 ° C. or higher and 50 ° C. or lower, and the second substrate temperature is 400 ° C. or higher and 600 ° C. or lower. In the semiconductor manufacturing apparatus according to the present invention (claim 4 or claim 6), the extinction time constant is preferably 50 msec or less.

Semiconductor manufacturing apparatus according to the present invention (claim 4)
In the above, the gas that generates oxygen radicals is O ₃ gas,
One gas or two or more gases selected from NO ₂ gas and C0 ₂ gas are preferable.

A semiconductor manufacturing apparatus according to the present invention (claim 4)
Where the organosilane gas is ethoxysilicate,
It may be a gas of one compound or a mixture of two or more compounds selected from methoxysilicate, hexamethyldisilicate, tetramethylsilane, and a silane polymer in which a hydrogen atom or a hydroxyl group is bonded to Si of the main chain. preferable.

Since the silane polymer contains carbon, when the silane polymer is used, carbon is not taken into the agglomerate film. Further, the present invention exerts a remarkable effect particularly when applied to a substrate having a concave portion having a high aspect ratio on the surface. That is,
The inside of the recess having a high aspect ratio can be completely filled with the silicon oxide film without causing film stress or the like.

[Operation] According to the method for manufacturing a semiconductor device of the present invention (claims 1 to 3), a silicon oxide aggregate film is formed in the aggregate film forming step. Although this aggregation film is reduced in thickness due to volume contraction, it is thinner than the silicon oxide film to be finally formed, and therefore the reduction in film thickness is small. At this stage, impurities such as carbon and hydrogen that cause film stress are present in the aggregate film.

In the subsequent reforming step, the impurities are removed from the aggregate film by reacting with oxygen radicals and evaporating into the vapor phase in the form of carbon oxide and water. At this time, as in the case of the aggregated film forming step, the aggregated film is reduced in thickness due to the volume contraction, but since it is thinner than the silicon oxide film to be finally formed, the reduced amount is small.

As described above, film reduction occurs in the aggregated film forming process and the reforming process. However, since this film reduction is small, by repeating a series of processes including the aggregated film forming process and the modifying process a plurality of times, A silicon oxide film having a desired film thickness can be easily formed. Therefore, according to the present invention, it is possible to easily obtain a silicon oxide film having a desired film thickness in which impurities such as carbon and hydrogen that cause film stress are not present.

Further, in the present invention, since agglomeration is used as the film forming mechanism, unlike the case of the normal conformal CVD method, the high aspect ratio concave portion (wiring groove, connection hole) formed on the substrate surface. It is possible to form a silicon oxide film having a good shape without voids. Since the silicon oxide film contains no impurities as described above, it has a film quality comparable to that of the silicon oxide film formed by the normal conformal CVD method.

A semiconductor manufacturing apparatus according to the present invention (claims 4 to 4)
According to claim 6), since the first substrate temperature control means and the second substrate temperature control means are provided, by using these substrate temperature control means, the first substrate temperature and the second substrate temperature
The substrate temperature can be switched quickly. Therefore, when the method for manufacturing a semiconductor device according to the present invention is carried out, it is possible to secure the productivity of the silicon oxide film to the extent that there is no industrial problem.

[0031]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a schematic diagram showing a schematic configuration of a condensation CVD apparatus according to a first embodiment of the present invention.

In the figure, 101 indicates a film forming chamber, and this film forming chamber 101 is provided with an exhaust port 10 through a gate valve 102.
Connected to 3. The film forming chamber 101 is configured to be evacuated from an exhaust port 103 by an exhaust pump (not shown), and the degree of vacuum achievement thereof is 2 × 10 ⁻⁷ Torr or more. The film forming chamber 101 is provided with a pressure gauge 104 used for controlling the pressure thereof.

The film forming chamber 101 is provided with first to fourth gas supply pipes 105 to 108. The first and second gas supply pipes 105 and 106 are for supplying TEOS gas which is an organic silane gas into the film forming chamber 101. The third gas supply pipe 107 is for supplying oxygen radical gas into the film forming chamber 101. The third gas supply pipe 108 is connected to the inert gas (N ₂ / A
r gas) is supplied to the inside of the film forming chamber 101.

Stop valves 109 to 112 are provided in the gas supply pipes 105 to 108, respectively. That is, the gas supply pipes 105 and 106 are connected to the TEOS supply source described later via the stop valves 109 and 110, respectively. The gas supply pipe 107 is connected to an oxygen radical source via a stop valve 111, and the gas supply pipe 108 is connected to an inert gas source via a stop valve 112.

A substrate support 114 made of quartz for mounting a semiconductor substrate 113 such as a silicon substrate is provided in the film forming chamber 101. The substrate support 114 has a hollow structure. By flowing a nitrogen gas cooled with liquid nitrogen or a heated (room temperature) nitrogen gas into the hollow structure, the temperature of the substrate support 114 is rapidly lowered or raised. You can warm it up. This temperature decrease or temperature increase is realized by the temperature decrease / temperature increase mechanism described below.

That is, the temperature lowering / heating mechanism is roughly divided into a nitrogen gas introducing pipe 115 for introducing nitrogen (N ₂ ) gas into the hollow structure of the substrate support 114, and the nitrogen gas introducing pipe 115. Nitrogen gas exhaust pipe 118 connected to a liquid nitrogen cooler 116 for cooling the nitrogen gas flowing through the chamber and a vacuum exhaust pump 117 for exhausting the nitrogen gas introduced from the nitrogen gas introduction pipe 115 into the hollow structure of the substrate support 114. It consists of

The nitrogen gas introducing pipe 115 is divided into two systems, one of which is provided with the substrate support 11 through the stop valve 119, the liquid nitrogen cooler 116 and the stop valve 120.
4 is a cooling piping system connected to the inside of the hollow structure, and the other is a non-cooling piping system connected to the inside of the hollow structure of the substrate support 114 via the stop valve 121 and the stop valve 120.

A mass flow meter 122 and a pressure gauge 123 are provided in the nitrogen gas introducing pipe 115 as shown in the figure. Further, the nitrogen gas exhaust pipe 118 is provided with a pressure gauge 124 and a stop valve 125 as shown.

The basic operation of this temperature lowering / heating mechanism is as follows. That is, when lowering the temperature of the substrate support 114, the stop valves 119 and 120 are opened and the stop valve 121 is closed. As a result, the liquid nitrogen cooler 11
The nitrogen gas cooled in 6 is introduced into the hollow structure of the substrate support 114, and the substrate support 114 is cooled. Therefore, the semiconductor substrate 113 is cooled.

On the other hand, when raising the temperature of the substrate support 114, the stop valves 119 and 120 are closed and the stop valve 121 is opened. As a result, the liquid nitrogen cooler 116
The nitrogen gas at room temperature, which is not cooled by, is introduced into the hollow structure of the substrate support 114, and the substrate support 114 is heated. Therefore, the semiconductor substrate 113 is heated.

Further, a maximum output of 1 kWa facing the substrate surface side through a quartz window 126 above the substrate support base 114.
tt 6 rod-shaped tungsten flash lamp 12
7 (flash lamp) is arranged. Above the tungsten flash lamp 127, the ultraviolet lamp 12 is provided.
8 and the reflection mirror 129 are sequentially arranged.

These tungsten flash lamps 12
By turning on 7, the substrate temperature can be set to a predetermined temperature (for example, 450 ° C.) in a short time of rising time constant (extinction time constant) of 10 msec. FIG. 2 shows the time dependence of the emitted light intensity of the tungsten flash lamp showing this. It can be seen from FIG. 2 that the substrate temperature can be set up to the maximum temperature of 550 ° C. in a short time, and that the substrate temperature immediately decreases after reaching the maximum temperature.

Note that the characteristic diagram of FIG. 2 is an example, and the range of substrate temperature at which high-speed temperature control can actually be performed in this system is 200.
６００600 ° C. Moreover, the extinction time constant is a predetermined value (50 m
50 m when using a lamp larger than
It is also possible to create a flash lamp having a small extinction time constant by using a shielding plate that can be opened and closed within sec.

When the substrate is cooled, the flash of the tungsten flash lamp 127 is stopped, and then the temperature of the substrate support base 114 is lowered by the temperature lowering / heating mechanism. For example, the mass flowmeter 122 is used to control the flow rate of nitrogen gas to 20 to 2
The substrate temperature is cooled within a range of −50 to 50 ° C. within 20 msec by controlling the pressure in the hollow structure portion of the substrate support base 114 to 100 Torr to 1 atom while controlling the pressure to 000 cm ³ / min. can do.

FIG. 3 is a schematic view showing a schematic structure of the above-mentioned TEOS gas supply section. In the figure, reference numeral 300 denotes a thermostatic chamber maintained at a predetermined temperature, for example, 80 ° C., and a TEOS cylinder 301 is accommodated in the thermostatic chamber 300. The constant temperature bath 300 is a gas pipe 302 that is branched into two.
The same size of the first and second gas reservoirs 303, 3
04.

The first gas reservoir 303 is connected to the first gas supply pipe 105. Of the gas pipes provided in the first gas reservoir 303, the portion inside the constant temperature bath 300 is TEO.
Like the S cylinder 301, it is kept at a predetermined temperature, for example, 80 ° C., and the portion coming out of the constant temperature bath 300 is kept at a predetermined temperature by the heater 306, for example, 80 ° C. In this way, TEOS agglomeration that occurs when the temperature is low can be effectively prevented.

Similarly, the second gas reservoir 304 is connected to the second gas supply pipe 106, and the portion of the gas pipe provided in the second gas reservoir 304 inside the thermostatic chamber 300 is TE.
Like the OS cylinder 301, it is kept at a predetermined temperature, for example, 80 ° C., and the portion coming out of the constant temperature bath 300 is kept at a predetermined temperature, for example, 80 ° C. by the heater 308 to effectively prevent the aggregation of TEOS.

The TEOS cylinder 301 has a main valve 309.
A separation valve 310 is provided in the gas pipe 302 between the first gas reservoir 303 and the original valve 309. Similarly, the second gas reservoir 304 and the main valve 30
A separation valve 311 is provided between the valve 9 and the valve 9. Further, the first gas reservoir 303 is provided with a pressure gauge 312, and the second gas reservoir 304 is provided with a pressure gauge 313. Further, in the figure, 314 is a valve for controlling the nitrogen (N) ₂ gas introduced into the TEOS cylinder 301.

In order to save space, the gas pipe 106 provided in the second gas reservoir 304 is omitted,
The second gas reservoir 304 is connected to the first via the separation valve 306.
It may be configured to be connected to the gas pipe provided in the gas reservoir 303. In this case, the second gas supply pipe 106 is eliminated and only the first gas supply pipe 105 is provided. Alternatively, the reverse gas pipe may be omitted.

The TEOS gas supply method is as follows. First, the first and second gas reservoirs 303 and 304 are exhausted. For this exhaust, for example, an exhaust pump (not shown) that exhausts the film forming chamber 101 is used. At this time, the separation valve 3
05 and 307 are opened and other valves are closed. A dedicated exhaust pump may be used instead of the exhaust pump.
In any case, if there is water in the pipe, TEOS is easily hydrolyzed and active silanol is formed.
It is preferable to maintain good moisture control to maintain low levels of residual moisture.

Next, the separation valves 305 and 307 are closed, the separation valves 310 and 311 are opened, and the TEOS cylinder 301 is opened.
Open the original valve 309 of. As a result, the TEOS gas flows into the first and second gas reservoirs 303 and 304.
At this time, the pressure gauges 312 and 312 are used to set a predetermined pressure in the first and second gas reservoirs 303 and 304, for example, 7
When the pressure reaches kPa, the separation valves 310 and 311 are closed.

Next, according to the timing chart of FIG.
Supply EOS gas. First, the separation valve 305 is opened for 2 seconds to supply the TEOS gas into the reaction chamber 101. At this time, the pressure of the first gas reservoir 303 finally reached 1 × 10 ⁻¹ Pa. Next, the separation valve 305 is closed and at the same time the separation valve 310 is opened to supply the TEOS gas to the first gas reservoir 303 for the next operation. Here, it took about 10 seconds for the pressure of the first gas reservoir 303 to reach about 7 KPa, and about 5 seconds for it to reach about 6.5 KPa.

Next, after the separation valve 305 is closed, ultraviolet rays are radiated from the side of the substrate on which the agglomerated film is formed by the ultraviolet lamp 128 for 2 seconds. Oxygen radicals obtained by microwave-discharging oxygen are supplied into the film forming chamber 101, but the amount thereof is small and oxygen that is not in a radical state is also introduced. Oxygen that is not in this radical state is activated by the above-mentioned ultraviolet irradiation, and a large amount of oxygen radicals are generated.

Next, the valve 307 is opened for 2 seconds, and the TEOS gas stored in the second gas reservoir 307 is supplied into the film forming chamber 101. At this time, the second gas reservoir 304
The final pressure of was the same as that of the first sump 30. Next, the separation valve 307 is closed and the separation valve 311 is opened at the same time, and the second gas reservoir 30 is opened for the next operation.
4 is supplied with TEOS gas.

Assuming that the TEOS gas stored in the first gas reservoir 303 and the second gas reservoir 304 as described above is once supplied into the reaction chamber 101 and the heat treatment is performed twice after the supply, is one cycle. The TEOS gas is supplied into the reaction chamber 101 twice in one cycle of operation. As a result, a silicon oxide agglomerate film is formed twice on the substrate 113 in one cycle of operation, and each agglomerate film is solidified by heat treatment in an oxygen radical atmosphere.

At this time, the thickness of the aggregated film formed on the substrate 113 by one cycle of operation was 22 nm. That is,
This means that 11 nm was formed in 4 seconds, and the overall deposition rate was 165 nm / min. This value means that it is sufficiently practical even if the above-mentioned deposition method is industrially used. The above values are merely examples, and the deposition rate can be increased to 0.5 μm / min by further increasing the gas reservoir and shortening the time of one cycle. Further, it is preferable that the time for introducing the TEOS gas and the time for irradiating the ultraviolet rays are substantially equal.

Next, the method for forming a silicon oxide film using the cohesive CVD apparatus of this embodiment will be described more specifically. First, the substrate 113 is transferred into the reaction chamber 101 and placed on the substrate support 114, and then the reaction chamber 101 is exhausted through the exhaust port 1.
Evacuate from 03 to 1 × 10 ⁻⁶ Pa or less. As the substrate 113, a silicon substrate as shown in FIG. 5A, that is, a silicon substrate having a groove with a high aspect ratio and a groove with a low aspect ratio formed on the surface was used. In the figure, 501 indicates a region where a groove with a high aspect ratio is formed, 503 indicates a region where a groove with a low aspect ratio is formed, and 502 and 504 indicate flat regions.

Next, the stop valves 119, 120, 12
5 is opened and the stop valve 121 is closed. That is,
The nitrogen gas cooled by the liquid nitrogen cooler 116 is caused to flow into the hollow structure of the substrate support 114. At this time, the mass flowmeter 122 controlled the flow rate of nitrogen gas to 1.1 l / min. In this case, the nitrogen passed through the liquid nitrogen cooler 116 is cooled to about -60 ° C, and the substrate support 114 is
The substrate 113 was cooled to 40 ° C and -35 ° C.

Next, the stop valve 111 is opened to supply a predetermined amount of O ₂ gas and O radical gas into the reaction chamber 101. The O radical gas has a flow rate of, for example, 200 cm ³ / m.
oxygen supplied in in at 2.45 GHz, 200 Watt
It is formed by being discharged by the microwave of t. In this state, the stop valve 109 is opened, and a certain amount of TEOS gas is intermittently supplied into the reaction chamber 101 by the procedure described above to form a silicon oxide aggregate film on the substrate 113.
After supplying TEOS gas for 2 seconds, the stop valve 10
Close 9,110.

FIG. 5B shows this step (aggregate film forming step).
Aggregate film (SiO _x film) 50 of silicon oxide formed by
2 is shown. The thickness of the aggregation film 505 at the bottom of the groove in the region 501 was about 20 mm, and the thickness of the aggregation film 505 at the bottom of the groove in the region 503 was about 18 mm. The results are from a scanning electron microscope (SEM).

Next, with the O radicals still flowing, the stop valve 119 is closed and the stop valve 121 is opened to allow uncooled nitrogen gas to flow into the hollow structure portion of the substrate support 114, and the tungsten flash lamp 127 and the ultraviolet lamp 128 are turned on. Lights up (reforming process). As a result, the substrate temperature reaches 400 ° C within 1 msec,
The aggregated film (SiO _x film) 505 could be effectively heat-treated in the O radical atmosphere.

At this time, the aggregation film (SiO _x film) 505
Is an SiO ₂ film that is solidified by heating with O radicals and heat, and the CH ₃ groups mixed during film formation react with O radicals and evaporate into the gas phase in the form of carbon oxides or water. To be removed. Similarly, H ₂ O and the like mixed during film formation are also removed. In this way, impurities that cause film stress are removed and reformed.

The thickness of the SiO ₂ film formed in one cycle including the aggregated film forming step and the modifying step was less than 20 nm at the groove bottom of the 501 region and slightly less than 18 nm at the groove bottom of the region 503. That is, since the aggregated film formed in one cycle is thin, the film loss is sufficiently small.

The reproducibility of the film thickness of the SiO ₂ film formed in one cycle is good, and the film thickness after 100 cycles is 50.
2 μm at the groove bottom of region 1 and 10 μ at the groove bottom of region 503
m. Moreover, the required time was 5 minutes, which was a sufficiently practical film forming rate. Further, the volume shrinkage is about 2% even at the heat treatment of 900 ° C., which is a sufficiently low practical value. In addition, the film stress after hardening is 3 × 10 ⁹ dyn /
cm ^2, which is a sufficiently low practical value.

By repeating the above-described one-cycle process including the aggregated film forming step and the modifying step a plurality of times, a desired thickness (thickness for completely filling the groove) with a sufficiently small amount of impurities and film reduction can be obtained. The silicon oxide film is formed.

According to this embodiment, the film stress and film loss, which are problems in the conventional cohesive CVD method, can be sufficiently improved.
Therefore, high aspect ratio recesses (wiring grooves, connection holes)
The cohesive CVD method, which is effective as a technique for burying an insulating film inside, can be made practical.

Next, a modified example of this embodiment will be described. That is, the case where hydrogen radicals are used instead of oxygen radicals in the reforming process will be described. When the condensed film obtained in the above-described aggregated film forming step was examined by secondary ion mass spectrometry (SIMS3), it was found that a large amount of C and H was contained in the inside thereof in addition to Si and 0.

The reason for this is that TEO which is a film forming gas.
The reaction in the gas phase of S gas did not proceed sufficiently, and condensation occurred without removing the alkyl group (C _n H _m ).
It is considered that the gas-phase TEOS gas and the gas having an alkyl group generated by the reaction are condensed and taken into the film.

This means that even if the condensed film is examined in situ by Fourier transform infrared spectroscopy, Si--CH ₃ and Si--C ₂
This is supported by the fact that an absorption peak based on the stretching vibration of H ₅ is seen.

Although oxygen radicals (O radicals) were used in this embodiment to remove these alkyl groups, it was found that using hydrogen radicals is also effective. That is, hydrogen is experimentally flown through a pipe for forming and supplying oxygen radicals, and microwave discharge is generated in the same manner as in the case of oxygen radicals to generate hydrogen radicals.
1 to supply a thin modified aggregate film in one cycle. In each step (aggregate film forming step / and reforming step), when the absorption spectrum by FT-IR transmission and impurities in the film by SIMS were examined, a large amount of C and H was detected in the condensed film in the aggregate film forming step. However, it was hardly detected in the reforming process.

It is considered that this is due to the following reason. Hydrogen radicals freely diffuse in the condensed film. Condensed film is about 20
Since it is as thin as nm, it is considered that hydrogen radicals diffuse uniformly to the bottom of the condensed film.

Hydrogen radicals are extremely active, and Si--C _n
When there is a bond of H _m , it is inserted into a bond of Si-C to form a dangling bond of Si and CH ₄ and C ₂ H.
Make saturated hydrocarbon compounds such as ₆ .

Since these compounds have a high vapor pressure, they diffuse in the condensed film and are desorbed from the surface into the vacuum to be removed from the condensed film. Therefore, it is considered that when the condensed film is exposed to the hydrogen radical atmosphere, the content rates of C and H decrease. (Second Embodiment) FIG. 6 is a schematic diagram showing a schematic configuration of a main part of a condensation CVD apparatus according to a second embodiment of the present invention. The parts corresponding to those of the condensation CVD apparatus in FIG. 1 are designated by the same reference numerals as those in FIG. 1, and detailed description thereof will be omitted.

The condensation CVD apparatus of this embodiment is different from that of the first embodiment in that it can generate a high concentration of oxygen radicals. The gas supply pipe 107 for supplying oxygen radicals to the film formation chamber 101 includes a stop valve 11
1 is connected to one end of a U-shaped trap (capture tube) 701. This trap 701 contains liquid nitrogen 7
It can be placed in a metal dewar 702 filled with 03 and is typically cooled to liquid nitrogen temperature.

The other end of the trap 701 is the stop valve 7
A pipe 706 to which O ₂ gas is supplied via 04 is connected, and a cavity 705 for causing microwave discharge is connected in the middle of the pipe 705. In addition, 7
00 indicates a stop valve connected to the exhaust pump.

In this embodiment, such a trap 70 is used.
1. A plurality of high-concentration oxygen radical generation units (hereinafter, simply referred to as units) each including a metal dewar 702, a cavity 705, and the like are provided. Note that FIG. 6 shows only one unit.

Next, a method for forming a silicon oxide film using the cohesive CVD apparatus of this embodiment will be described. First, the stop valve 111 is closed and the stop valves 700, 7 are closed.
04 is opened, the flow rate of O ₂ gas flowing in the pipe 706 is set to 200 cc / min by a mass flow meter (not shown), and the cavity 705 is set to a frequency of 2.45 GHz.
Oxygen radicals are generated by operating at an electric power of 200 Watts to cause microwave discharge.

The oxygen radicals are effectively captured by the trap 701 cooled to the liquid nitrogen temperature, and a large amount of oxygen radicals are stored in the trap 701. In addition,
The trap 701 contains oxygen (O ₂ , O ₂ which is not in a radical state).
₃ ) is also stored.

Then, the metal Dewar bottle 702 is lowered to warm the trap 701 to a predetermined temperature (20 ° C. or lower) in a short time (10 sec or less). During the initial period when the temperature rise is slow, the stop valve 700 may be opened to evacuate.

Next, the stop valve 700 is closed to increase the pressure in the trap 701, and when the pressure reaches a desired level, the stop valve 111 is opened to provide a high concentration of oxygen radical gas and oxygen (O ₂ , O ₃ ) gas. Is supplied into the film forming chamber 101.

Here, the pressure in the trap 702 before opening the stop valve 1110 is usually 10 Torr or less, but it is desirable to be as high as possible within a range where the high vacuum exhaust system of the film forming chamber 101 does not fail.

Further, the timing of introducing the high-concentration oxygen radical gas and the oxygen (O ₂ , O ₃ ) gas into the film forming chamber 101 is the same as that of the first embodiment. It was confirmed that the condensation property of the organic silane was improved by using a high concentration of oxygen radicals in the aggregated film forming step. Got S
As a result of the impurity analysis of the iO ₂ film, the contents of C and H are extremely small. Specifically, C is several atm% and H is S
It was a background level by IMS. Also, by using a high concentration of oxygen radicals in the reforming process, Si
It was confirmed that the C and H concentrations in the O ₂ film could be further reduced. (Third Embodiment) FIGS. 7A to 7C are process sectional views showing a method for manufacturing a semiconductor device according to a third embodiment of the present invention. This is an example in which the present invention is applied to an interlayer insulating film.

First, as shown in FIG. 7A, a 0.2 μm thick SiO 2 film is formed on a silicon substrate 801 by a thermal oxidation method.
_{2 The} film 802 is formed. Next, as shown in FIG.
Al-1% Si-0.2 SiO using a conventional light exposure method
_An Al alloy wiring pattern 803 is formed on the _second film 802. The minimum wiring width of the Al alloy wiring pattern 803 is 0.2.
μm, the maximum wiring width is 2 μm, and the minimum space is 0.
The width of the maximum space is 15 μm and 10 μm. Therefore, a pattern having a high aspect ratio is present on the surface.

Next, as shown in FIG. 9A, a thickness of 0.0 for protecting the surface is formed by using a normal plasma CVD method.
A SiO ₂ film 804 of about 5 to 0.1 μm is formed on the entire surface. Next, as shown in FIGS. 7B and 7C, according to the procedure of the first embodiment, the aggregation film forming step and the modifying step are repeated to form a SiO ₂ film 805 having a thickness of 0.7 μm. Form on the entire surface.

FIG. 7B is a sectional view during the formation of the SiO ₂ film 805, and FIG. 7C is a sectional view after the completion.
It can be seen from FIG. 7C that even if a pattern having a high aspect ratio is present on the surface, the SiO ₂ film 805 is filled from the bottom of the groove without voids.

The amount of impurities remaining in the SiO ₂ film 805 and the film stress were almost the same as those in the first embodiment. However, in the present embodiment, the Al alloy wiring 803
Therefore, the heat treatment temperature in the reforming step is set to 500 ° C. or lower. At this temperature, the volume shrinkage of the condensed film was at a negligible level.

Also, in the reforming process, even if hydrogen radicals were used, good results were obtained as in the above modification. This is an expected result, because the shape of the surface of the base substrate is simply changed. By this method, the space between Al alloy wirings is 0.1 to 2 μm, and the thickness of Al alloy wiring is 0.4 to
When the condensed film was embedded using a sample of 1.0 μm, it could be embedded flat without a “nest” up to a maximum aspect ratio (= thickness of Al alloy wiring / space between Al alloy wirings). .

The present invention is not limited to the above embodiment. For example, in the above embodiment, the O radical was generated by the microwave discharge of O ₂ , but the O radical may be generated by another method.

For example, ozone (O ₃ ) may be used.
This is because O radicals are generated by O ₃ → O ^* + O ₂ . This O radical is ³ P like the above O radical.
It is in a state.

It is said that the O radical in the ³ P state mainly contributes to the atom abstraction reaction. This means that the outermost electron spin state of 0 is (up, up) or (do
Because it is a combination of wn and down), it cannot be interrupted between the atoms forming the bond.

Here, in the case where O ₃ is decomposed to generate O radicals, when UV light is irradiated, O in the ¹ D state is generated.
Radicals are mainly generated. The O radical in the ¹ D state is likely to interrupt the atoms forming the bond because the electron spin state of the outermost shell is a pair of (up, down).
Therefore, to create a silane polymer main chain hydrogen atom or a hydroxyl group is an organic silane is bound, ¹ is important to make the O radical D state, ultraviolet lamp even when using the O ₃ as O radical source Was effective. In addition, as other O radical source, for example, NO ₂ ,
CO ₂ can be mentioned. Also, O radicals and H radicals may be used at the same time.

Further, in the above-mentioned embodiment, other organic silane described in the case of using TEOS as the film forming material may be used. For example, tetramethooxysilicate (Si (OCH ₃ ) ₄ , TMOS), tetramethylsilane (Si (CH ₃ ) ₄ , TMS), tetramethylsilane (TMS), etc. which are liquid at room temperature and have a vapor of several Torr. Any organic silane with pressure may be used. In addition, various modifications can be made without departing from the scope of the present invention.

[0093]

As described above in detail, according to the present invention, by repeating the aggregated film forming step and the reforming step, a silicon oxide film having a predetermined thickness that does not contain impurities causing film stress or the like is obtained. Can be easily obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of a condensation CVD apparatus according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between a lighting time of a tungsten flash lamp and a substrate temperature.

FIG. 3 is a schematic diagram showing a schematic configuration of a gas supply unit of TEOS of the condensation CVD apparatus of FIG.

FIG. 4 is a timing chart for explaining a TEOS gas supply method.

FIG. 5 is a sectional view for explaining the method for forming a silicon oxide film according to the first embodiment of the present invention.

FIG. 6 is a schematic diagram showing a schematic configuration of a main part of a condensation CVD apparatus according to a second embodiment of the present invention.

FIG. 7 is a process sectional view showing a method for manufacturing a semiconductor device according to a third embodiment of the present invention.

[Explanation of symbols]

101 ... Film-forming chamber 102 ... Gate valve 103 ... Exhaust port 104 ... Pressure gauge 105 ... First gas supply pipe 106 ... Second gas supply pipe 107 ... Third gas supply pipe 108 ... Fourth gas supply pipe 109 Stop valve 110 Stop valve 111 Stop valve 112 Stop valve 113 Semiconductor substrate 114 Substrate support 115 Nitrogen gas introduction pipe 116 Liquid nitrogen cooler 117 Vacuum exhaust pump 118 Nitrogen gas exhaust pipe 119 Stop Valve 120 ... Stop valve 121 ... Stop valve 122 ... Mass flow meter 123 ... Pressure gauge 124 ... Pressure gauge 125 ... Stop valve 126 ... Quartz window 127 ... Tungsten flash lamp (flash lamp) 128 ... UV lamp 129 ... Reflecting mirror 301 ... TEOS Cylinder 302 Gas pipe 303 ... First gas reservoir 304 ... Second gas reservoir 305 ... Separation valve 306 ... Heater 307 ... Separation valve 308 ... Heater 309 ... Main valve 310 ... Separation valve 311 ... Separation valve 312 ... Pressure gauge 313 ... Pressure gauge 501 ... Region in which high aspect ratio groove is formed 502 ... Flat region 503 ... Region in which low aspect ratio groove is formed 504 ... Flat region 505 ... Aggregation film 701 ... Trap (capture tube) 702 ... Metal dewar bottle 703 ... Liquid nitrogen 704 ... Stop valve 705 ... Cavity 706 ... Piping 801 ... Silicon substrate 802 ... Thermal oxide SiO ₂ film 803 ... Al alloy wiring pattern 804 ... Plasma CVD SiO ₂ film 805 ... Aggregated CVD SiO ₂ film

Claims (6)

[Claims] 1. A semiconductor substrate first housed in a processing container.
While the substrate temperature is set to, an oxygen source gas containing at least one gas of an oxygen radical gas and a gas that generates oxygen radicals, and a film forming gas consisting of an organic silane gas are introduced, and the reaction of the film forming gas By condensing the produced gas phase intermediate on the semiconductor substrate,
An aggregate film forming step of forming an aggregate film of silicon oxide on the semiconductor substrate; and setting the semiconductor substrate to a second substrate temperature higher than the first substrate temperature, and at least oxygen radical gas and hydrogen radical gas. By heat-treating the aggregated film in an atmosphere containing one gas, by repeating a series of steps consisting of a modifying step of modifying the aggregated film, the aggregated film forming step, and the modifying step, a plurality of times. And a step of forming a silicon oxide film having a desired film thickness, the method for manufacturing a semiconductor device. 2. In the modifying step, a flash lamp having an extinction time constant of a predetermined value or less is used to irradiate the semiconductor substrate with light from the side where the agglomerate film is formed, whereby the second substrate is irradiated. The method for manufacturing a semiconductor device according to claim 1, wherein the semiconductor substrate is set at a temperature. 3. At least one of the oxygen radical gas and the hydrogen radical gas in the reforming step uses an ultraviolet lamp having an extinction time constant of a predetermined value or less to generate a gas that generates oxygen radicals and a hydrogen radical gas. 2. The method for manufacturing a semiconductor device according to claim 1, wherein the gas is generated by irradiating a gas containing at least one of the gases described above with ultraviolet rays. 4. A processing container on which a semiconductor substrate is housed, and in the processing container, an oxygen source gas containing at least one of an oxygen radical gas and a gas generating an oxygen radical and an organic silane gas are provided on the semiconductor substrate. A film forming gas for forming an aggregate film of silicon oxide, and a gas supply means for supplying a gas containing at least one gas of an oxygen radical gas and a hydrogen radical gas as an atmosphere gas for heat-treating the aggregate film; A decompression means for decompressing the inside of the processing container, a substrate supporting base provided in the processing container and having a hollow structure for mounting the semiconductor substrate, and a gas flowing in the hollow structure of the substrate supporting base. First substrate temperature control means for controlling the temperature of the semiconductor substrate by controlling the temperature of the semiconductor substrate, and the side on which the aggregation film is formed. And a second substrate temperature control means comprising a flash lamp having an extinction time constant of a predetermined value or less for irradiating the semiconductor substrate with light to control the temperature of the semiconductor substrate. apparatus. 5. The gas supply means comprises an ultraviolet lamp having an extinction time constant of not more than a predetermined value for irradiating the oxygen supplied into the processing container with ultraviolet rays to generate oxygen radicals. 4. The semiconductor manufacturing apparatus according to item 4. 6. The semiconductor manufacturing apparatus according to claim 4, wherein the gas supply means causes the oxygen gas subjected to the microwave discharge to flow into a temperature-controlled trapping tube.