JP2002043313A - Forming method of silicon oxide film and forming device thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the forming method of a silicon oxide film which can increase the film forming rate of a silicon oxide film which is formed on a body to be treated, and to provide the forming device of the silicon oxide film. SOLUTION: The forming device of a silicon oxide film is constituted in a structure that a first gas introducing tube 13 for feeding dichlorosilane and a second gas introducing tube 14 for feeding dinitrogen monoxide are provided under the lower part of a reaction tube 2 of a heat-treating unit 1. A heater 15 is interposingly provided on the tube 14. The heater 15 heats the dinitrogen monoxide fed in the heater 15 to 700 deg.C or higher. The heated dinitrogen monoxide is fed in the reaction tube 2 via the tube 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for forming a silicon oxide film, and more particularly to a method and an apparatus for forming a silicon oxide film for forming a silicon oxide film on an object to be processed, for example, a semiconductor wafer.

[0002]

2. Description of the Related Art In a semiconductor device manufacturing process, a chemical vapor deposition (CVD) method is used.
A process such as n)) forms a silicon oxide film on an object to be processed, for example, a semiconductor wafer.

[0003] This silicon oxide film is formed, for example, by the following method.
It is performed as follows. First, it consists of a silicon substrate
The semiconductor wafer is placed in a heat treatment apparatus. Next, heat treatment
A predetermined pressure, for example, 13.3 Pa (0.1 T)
orr) to 1330 Pa (10 Torr)
Both are heated to a predetermined temperature, for example, 700 ° C to 900 ° C
I do. Then, a processing gas, for example,
Chlorosilane (SiH ₂Cl₂) And nitrous oxide (N
₂When O) is introduced for a predetermined time, dichlorosilane is oxidized.
To form a silicon oxide film on the surface of the semiconductor wafer.
You. The silicon oxide film thus formed is dense and
It has the characteristics that the edge is good and the film is hardly peeled off.
You.

[0004]

However, when a silicon oxide film is formed on a semiconductor wafer by the above-described method, there is a problem that the film formation speed of the silicon oxide film formed on the semiconductor wafer is low.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method and an apparatus for forming a silicon oxide film capable of increasing the film forming speed of a silicon oxide film formed on an object to be processed. Aim.

[0006]

To achieve the above object, a method for forming a silicon oxide film according to a first aspect of the present invention is to provide a method for forming a silicon oxide film in a reaction chamber containing an object to be processed at a predetermined temperature and a predetermined pressure. And forming a silicon oxide film on the object by supplying a silane-based gas and dinitrogen monoxide into the reaction chamber, wherein the dinitrogen monoxide is reduced to at least 700. C., and the heated nitrous oxide is supplied to the reaction chamber.

According to this configuration, nitrous oxide is heated to at least 700 ° C., and the heated nitrous oxide is supplied to the reaction chamber. Therefore, thermal decomposition of nitrous oxide is promoted to generate a large amount of oxygen, and oxidation of the silane-based gas in the reaction chamber is promoted. Therefore, the deposition rate of the silicon oxide film formed on the object can be increased.

It is preferable that the nitrous oxide is heated to 750 ° C. to 950 ° C. and supplied to the reaction chamber. When dinitrogen monoxide is heated to 750 ° C. to 950 ° C. and supplied to the reaction chamber, the thermal decomposition of dinitrogen monoxide can be further promoted, and the deposition rate of the silicon oxide film formed on the object can be reduced. Can be raised further.

The reaction chamber is composed of, for example, an inner tube for accommodating the object to be processed, and an outer tube with a ceiling formed to cover the inner tube. Then, the silane-based gas and the nitrous oxide are supplied into the inner tube.

According to a second aspect of the present invention, there is provided an apparatus for forming a silicon oxide film, comprising: a reaction chamber for accommodating an object to be processed and having a heating unit capable of setting a predetermined temperature; Supply means for supplying nitrogen, second supply means for supplying dinitrogen monoxide into the reaction chamber, and heating means interposed in the second supply means for heating the nitrous oxide to a predetermined temperature And an exhaust unit that has an exhaust pipe connected to the reaction chamber, and that can set a predetermined pressure by exhausting gas in the reaction chamber from the exhaust pipe, and at least the nitrous oxide by the heating unit. Control means for heating to 700 ° C. and supplying the heated nitrous oxide to the reaction chamber via the second supply means.

According to this configuration, the nitrous oxide is heated to at least 700 ° C. by the heating means, and the heated nitrous oxide is supplied to the reaction chamber through the second supply means. Therefore, thermal decomposition of nitrous oxide is promoted to generate a large amount of oxygen, and oxidation of the silane-based gas in the reaction chamber is promoted. Therefore, the deposition rate of the silicon oxide film formed on the object can be increased.

The control means preferably causes the heating means to heat the nitrous oxide at 750 ° C. to 950 ° C. When dinitrogen monoxide is heated to 750 ° C. to 950 ° C., thermal decomposition of dinitrogen monoxide can be further promoted, and the deposition rate of the silicon oxide film formed on the object can be further increased. .

The second supply means is provided with a supply pipe communicating with the reaction chamber and having the heating means interposed therebetween. And on the downstream side of the heating means of the supply pipe,
A narrow portion for reducing the diameter of the supply pipe is provided. For this reason, a sufficient residence time is given to nitrous oxide passing through the heating means, and the heating efficiency by the heating means is improved.

The reaction chamber comprises, for example, an inner tube for accommodating the object to be processed and an outer tube with a ceiling formed so as to cover the inner tube. Then, the first supply means and the second supply means are arranged so as to face the inside of the inner tube.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method and an apparatus for forming a silicon oxide film according to an embodiment of the present invention will be described with reference to FIG. An example will be described.

As shown in FIG. 1, the heat treatment apparatus 1 includes a substantially cylindrical reaction tube 2 whose longitudinal direction is directed vertically. The reaction tube 2 has an inner tube 3 inside which a film formation region is formed.
And an outer tube 4 having a ceiling and formed so as to cover the inner tube 3 and to have a certain distance from the inner tube 3. The inner tube 3 and the outer tube 4 are formed of a heat-resistant material, for example, quartz.

Below the outer tube 4, a manifold 5 formed of a stainless steel (SUS) formed in a cylindrical shape is arranged. The manifold 5 is airtightly connected to the lower end of the outer tube 4. The inner pipe 3 projects from the inner wall of the manifold 5 and is supported by a support ring 6 formed integrally with the manifold 5.

A lid 7 is arranged below the manifold 5, and the lid 7 is configured to be vertically movable by a boat elevator 8. When the lid 7 is raised by the boat elevator 8, the lower side of the manifold 5 is closed.

A wafer boat 9 made of, for example, quartz is placed on the lid 7. An object to be processed, for example, a semiconductor wafer 10 is provided at a predetermined interval in the vertical direction on the wafer boat 9.
For example, a plurality of sheets are accommodated at intervals of 5.2 mm.

A heat insulator 11 is provided around the reaction tube 2 so as to surround the reaction tube 2. On the inner wall surface of the heat insulator 11, for example, a heater
Is provided. Then, the inside of the reaction tube 2 is set to a predetermined temperature by the heating of the heater 12.

A plurality of gas introduction pipes are inserted through the side of the manifold 5. In the present embodiment, two gas introduction pipes, that is, a first gas introduction pipe 13 and a second gas introduction pipe 14 are inserted into the side surface of the manifold 5.

The first gas introduction pipe 13 is disposed so as to face the inside of the inner pipe 3. For example, as shown in FIG. 1, the first gas introduction pipe 13 is inserted from the side of the manifold 5 below the support ring 6 (below the inner pipe 3). And
From the first gas introduction pipe 13, for example, dichlorosilane (Si
A silane-based gas such as H ₂ Cl ₂ ) is introduced into the inner tube 3.

The second gas introduction pipe 14 is disposed so as to face the inside of the inner pipe 3, and, like the first gas introduction pipe 13, from the side of the manifold 5 below the support ring 6 (below the inner pipe 3). The second gas introduction pipe 14 is inserted. And the second
Dinitrogen monoxide (N ₂ O) is supplied from the gas introduction pipe 14 to the inner pipe 3.
Introduced within.

A heater 15 is interposed in the second gas introduction pipe 14. The heater 15 is provided with a heater composed of, for example, a resistance heating element, and heats nitrous oxide supplied into the heater 15 to a predetermined temperature. Then, the heated nitrous oxide is supplied into the reaction tube 2 via the second gas introduction tube 14.

Further, a narrow diameter portion 16 is formed on the downstream side of the heater 15 of the second gas introduction pipe 14. FIG. 2 shows an enlarged view of the vicinity of the narrow diameter portion 16. As shown in FIG.
Reference numeral 6 denotes a projection 16a and an orifice 16b. The protrusion 16a is formed so as to project from the inner peripheral surface of the second gas introduction pipe 14 so as to reduce the inner diameter of the second gas introduction pipe 14. In the present embodiment, the protrusion 16a protrudes from the inner peripheral surface of the second gas introduction pipe 14 in the vertical direction, and is formed in a ring shape as a whole. And the protrusion 16a
Defines an orifice 16b. In the present embodiment, the inner diameter of the second gas introduction pipe 14 is formed to be 20 mm, and the diameter of the orifice 16b is formed to be about 0.6 mm.

A discharge port 17 is provided on a side surface of the manifold 5. The discharge port 17 is provided above the support ring 6 and communicates with a space formed between the inner tube 3 and the outer tube 4 in the reaction tube 2. Then, the processing gas is supplied from the first gas introduction pipe 13 and the second gas introduction pipe 14 into the inner pipe 3 to perform a film forming process, and a reaction product generated by the film forming process is supplied to the inner tube 3 and the outer tube 3. 4 and is discharged to the discharge port 17.

An exhaust pipe 18 is hermetically connected to the outlet 17. A valve 19 and a vacuum pump 20 are provided in the exhaust pipe 18. The valve 19 controls the opening degree of the exhaust pipe 18 to control the pressure in the reaction pipe 2 and the pressure in the exhaust pipe 18 to a predetermined pressure. The vacuum pump 20 is connected to the exhaust pipe 18.
The gas in the reaction tube 2 is evacuated through the, and the pressures in the reaction tube 2 and the exhaust tube 18 are adjusted.

The boat elevator 8, the heater 12 for raising the temperature,
First gas introduction pipe 13, second gas introduction pipe 14, heater 1
5, a control unit 21 is connected to the valve 19 and the vacuum pump 20. The control unit 21 is configured by a microprocessor, a process controller, and the like, measures the temperature, pressure, and the like of each unit of the heat treatment apparatus 1 and outputs a control signal or the like to each of the above units based on the measurement data. Control each part.

Next, a method for forming a silicon oxide film using the heat treatment apparatus 1 configured as described above will be described by taking as an example a case where a silicon oxide film is formed on a semiconductor wafer 10. In the following description, the operation of each unit constituting the heat treatment apparatus 1 is controlled by the control unit 21.

First, the wafer boat 9 containing the semiconductor wafers 10 is placed on the lid 7 with the lid 7 lowered by the boat elevator 8. Next, the lid 7 is raised by the boat elevator 8, and the wafer boat 9 (semiconductor wafer 10) is loaded into the reaction tube 2. Thus, the semiconductor wafer 10 is accommodated in the inner tube 3 of the reaction tube 2 and the reaction tube 2 is sealed.

The reaction tube 2 is heated by the heater 12 for raising the temperature.
The inside is heated to a predetermined temperature suitable for forming a silicon oxide film, for example, 700 ° C. to 900 ° C.

Further, the heater 15 is heated to a predetermined temperature by a heater (not shown). In order to study the temperature of the heater 15, the relationship between the temperature of the heater 15 and the amount of oxygen generated by the thermal decomposition of nitrous oxide was examined. FIG. 3 shows the amount of oxygen at each temperature. As shown in FIG. 3, it was confirmed that when dinitrogen monoxide was heated at 700 ° C. or more, the amount of oxygen generated by thermal decomposition increased. When the amount of oxygen generated by the thermal decomposition increases, the first gas introduction pipe 1
Oxidation of dichlorosilane supplied from 3 can be promoted, and the deposition rate of the silicon oxide film formed on the semiconductor wafer 10 can be increased. Therefore, the temperature of the heater 15 is set to 700 ° C. or higher.

In particular, when the temperature of the heater 15 is set to 750 ° C. or more, the amount of oxygen generated by thermal decomposition is greatly increased. Therefore, the temperature of the heater 15 is preferably 750 ° C. or more. However, since nitrous oxide is thermally decomposed almost completely at 950 ° C., even if the heater 15 is heated to a temperature higher than 950 ° C., the amount of oxygen does not increase. For this reason, it is preferable that the temperature of the heater 15 be 750 ° C. to 950 ° C.

After sealing the reaction tube 2, the vacuum pump 20 is driven while controlling the opening of the valve 19, and the reaction tube 2 is closed.
Evacuate the gas inside and start decompression. The gas in the reaction tube 2 is discharged until the pressure in the reaction tube 2 becomes a predetermined pressure, for example, 47 Pa (0.35 Torr) from the normal pressure.

The pressure in the heater 15 is set to, for example, 0.
1 kPa to 90 kPa (0.75 Torr to 677 To
Reduce the pressure slightly to rr). In this embodiment, 85 kPa
(640 Torr). The reason why the pressure inside the heater 15 is set to be higher than the pressure inside the reaction tube 2 is that the thermal decomposition efficiency (heating efficiency) generally tends to deteriorate under reduced pressure. It is to improve.

The pressure in the reaction tube 2 is 47 Pa (0.35 T
orr), a predetermined flow rate from the first gas introduction pipe 13, for example, 0.15 liter / min (150 sc)
cm) of dichlorosilane is introduced into the inner tube 3.

Further, a predetermined flow rate, for example, 0.3 liter / min (300 sccm) is supplied from the second gas introduction pipe 14.
Is supplied to the heater 15. The dinitrogen monoxide supplied to the heater 15 is heated in the heater 15 to cause thermal decomposition to generate oxygen, and the oxygen is generated in the state through the second gas introduction pipe 14. It is introduced into the tube 3.

Here, the heater 15 of the second gas introduction pipe 14
Since a narrow diameter portion 16 (orifice 16b) is formed on the downstream side, a sufficient residence time is given to nitrous oxide passing through the heater 15. Therefore, the heating efficiency of the heater 15 is improved, and the thermal decomposition of nitrous oxide is promoted.

Oxygen introduced into the inner tube 3 oxidizes dichlorosilane supplied into the inner tube 3 to produce silicon dioxide (S
iO ₂ ). Furthermore, since the nitrous oxide introduced into the inner tube 3 is heated to 700 ° C. or higher, the thermal decomposition of the nitrous oxide is promoted during the heating in the inner tube 3. Therefore, the amount of oxygen in the inner tube 3 increases, and the oxidation of dichlorosilane supplied into the inner tube 3 can be promoted, and the amount of silicon dioxide generated can be increased.

The generated silicon dioxide is supplied to the semiconductor wafer 10
Feed on and deposit. Then, when dichlorosilane and nitrous oxide are supplied for a predetermined time, for example, 60 minutes,
A silicon oxide film is formed on semiconductor wafer 10. At this time, since the generation amount of silicon dioxide can be increased, the deposition rate of the silicon oxide film formed on the semiconductor wafer 10 can be increased.

In order to confirm the effects of the present invention, a heater 15
FIG. 4 shows the deposition rate (D / R: Deposition Rate) of the formed silicon oxide film when the heating temperature is changed. For comparison, FIG. 4 also shows the film formation rate of the silicon oxide film when dinitrogen monoxide is not heated by the heater 15.

As shown in FIG. 4, it was confirmed that when dinitrogen monoxide was heated by the heater 15 at a temperature of 700 ° C. or more, the deposition rate of the silicon oxide film was increased. This result corresponds to the amount of oxygen generated by the thermal decomposition shown in FIG. 3, and the oxidation of the dichlorosilane can be promoted by the increase of the amount of the oxygen generated by the thermal decomposition, which is formed on the semiconductor wafer 10. It was confirmed that the deposition rate of the silicon oxide film was increased.

Further, since the nitrous oxide which has not been thermally decomposed by the heating in the heater 15 is also heated, it is easily thermally decomposed by the heating in the inner tube 3 to promote the thermal decomposition of the nitrous oxide. be able to. For this reason, oxidation of dichlorosilane can be promoted, and the deposition rate of the silicon oxide film formed on the semiconductor wafer 10 can be increased.

Further, dinitrogen monoxide is added to the heater 15 for 75 hours.
When heating at 0 ° C. or higher, the deposition rate of the silicon oxide film is significantly increased, and even when heating nitrous oxide to a temperature higher than 950 ° C. with the heater 15, the deposition rate of the silicon oxide film may not increase. , And the amount of oxygen generated by the thermal decomposition shown in FIG. For this reason, when nitrous oxide is heated at 750 ° C. to 950 ° C. by the heater 15, the film formation speed of the silicon oxide film can be particularly increased.

The pressure inside the heater 15 is set to 84 kPa
(630 Torr), the heating efficiency in the heater 15 can be improved. Therefore, thermal decomposition of nitrous oxide is promoted, and the deposition rate of the silicon oxide film can be increased.

Further, the heater 15 of the second gas introduction pipe 14
Since a narrow diameter portion 16 (orifice 16b) is formed on the downstream side, a sufficient residence time is given to nitrous oxide passing through the heater 15, and the heating efficiency of the heater 15 is improved. Therefore, thermal decomposition of nitrous oxide is promoted, and the deposition rate of the silicon oxide film can be increased.

When the silicon oxide film is formed on the surface of the semiconductor wafer 10, the supply of the processing gas from the first gas introduction pipe 13 and the second gas introduction pipe 14 is stopped. After the gas in the reaction tube 2 is exhausted from the exhaust port 17, the inside of the reaction tube 2 is returned to normal pressure. Then, the boat elevator 8 unloads the wafer boat 9 (semiconductor wafer 10) from the reaction tube 2.

As described above, according to the present embodiment, nitrous oxide is heated to 700 ° C. or more by the heater 15 and the heated nitrous oxide is introduced into the inner tube 3. In addition, thermal decomposition of nitrous oxide is promoted, and the deposition rate of the silicon oxide film can be increased.

The present invention is not limited to the above embodiment, and may be, for example, in the following case.

In the present embodiment, the present invention has been described by taking as an example the case where dichlorosilane is used as the silane-based gas.
The silane-based gas used in the present invention is not limited to dichlorosilane.
H ₄ ) and disilane (Si ₂ H ₆ ).

In the present embodiment, the pressure (85 kPa (640 Torr)) in the heater 15 is higher than the pressure (47 Pa (0.35 Torr)) in the reaction tube 2, but the present invention is not limited to this. Instead, for example, the pressure in the heater 15 may be substantially the same as the pressure in the reaction tube 2. Also in this case, thermal decomposition of dinitrogen monoxide is promoted, and the deposition rate of the silicon oxide film can be increased.

It is not necessary to provide the narrow diameter portion 16 in the present embodiment. Also in this case, thermal decomposition of dinitrogen monoxide is promoted, and the deposition rate of the silicon oxide film can be increased.

In the present embodiment, the orifice 16b is formed to have a thickness of about 0.6 mm. However, the present invention is not limited to this, and a sufficient retention of dinitrogen monoxide passing through the heater 15 is performed. Any size may be used as long as time is given. In the present embodiment, the heater 1 of the second gas introduction pipe 14 is used.
A narrow portion 16 (orifice 16b) is formed on the downstream side of the nozzle 5, but any structure may be used as long as a sufficient residence time is given to nitrous oxide passing through the heater 15. 15 so that the time for passing through the heater 15 becomes longer.
5 may have a structure in which the flow path through which nitrous oxide flows is elongated. Also in this case, the heating efficiency of the heater 15 can be improved.

In the present embodiment, the silicon oxide film forming apparatus is exemplified by a batch type vertical heat treatment apparatus having a double tube structure in which the reaction tube 2 is composed of an inner tube 3 and an outer tube 4. Although the present invention has been described, the present invention is not limited to this, and can be applied to various processing apparatuses that form an oxide film on a target object. Further, the object to be processed is not limited to a semiconductor wafer, but can be applied to, for example, a glass substrate for an LCD.

[0055]

As described above, according to the present invention,
The deposition rate of the silicon oxide film formed on the object can be increased.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a heat treatment apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing the vicinity of a heater according to the embodiment of the present invention.

FIG. 3 is a table showing a relationship between a heater temperature and an oxygen amount according to the embodiment of the present invention.

FIG. 4 is a table showing a relationship between a heater temperature and a film forming rate according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat treatment apparatus 2 Reaction tube 3 Inner tube 4 Outer tube 10 Semiconductor wafer 12 Heater for heating 13 First gas introduction tube 14 Second gas introduction tube 15 Heater 16 Narrow part 21 Control part

Continuing on the front page (72) Inventor, Hisashi Kato 52, Matsunaga, Iwatado, Esashi-shi, Iwate Prefecture Tokyo Electron Tohoku Co., Ltd. Tohoku Office F-term (reference) 4G072 AA25 BB09 GG03 HH03 HH07 JJ26 NN13 RR03 RR11 UU01 4K030 AA06 AA24 BA44 CA04 EA03 EA05 FA10 JA10 KA05 LA15 5F045 AB32 AC05 AD11 AD12 AD13 AE13 AF01 BB09 DP19 EC02 EE07 EM10 5F058 BA20 BC02 BF04 BF24 BF29 BF37 BF38 BG01 BG02 BG03 BJ01

Claims (7)

[Claims] 1. A reaction chamber containing an object to be processed is set at a predetermined temperature and a predetermined pressure, and a silane-based gas and nitrous oxide are supplied into the reaction chamber to oxidize silicon to the object to be processed. A method for forming a silicon oxide film, comprising: heating the nitrous oxide to at least 700 ° C. and supplying the heated nitrous oxide to the reaction chamber. Method of forming a film. 2. The method for forming a silicon oxide film according to claim 1, wherein said nitrous oxide is heated to 750 ° C. to 950 ° C. and supplied to said reaction chamber. 3. The reaction chamber includes an inner tube for accommodating the object to be processed, and an outer tube having a ceiling formed to cover the inner tube. 3. The method for forming a silicon oxide film according to claim 1, wherein nitrogen is supplied into the inner tube. 4. A reaction chamber for accommodating an object to be processed and having a heating unit which can be set at a predetermined temperature, first supply means for supplying a silane-based gas into the reaction chamber, and monoxide in the reaction chamber. A second supply unit for supplying dinitrogen, a heating unit interposed in the second supply unit, for heating the nitrous oxide to a predetermined temperature, and an exhaust pipe connected to the reaction chamber, An exhaust unit that exhausts gas in the reaction chamber from the exhaust pipe and can set the pressure to a predetermined pressure; and the heating unit reduces the nitrous oxide to at least 70%.
0 ° C., and the heated nitrous oxide is removed from the second
Control means for supplying to the reaction chamber via supply means; and a silicon oxide film forming apparatus. 5. The apparatus according to claim 4, wherein said control means causes said heating means to heat said nitrous oxide at 750 ° C. to 950 ° C. 6. The second supply means includes a supply pipe communicating with the reaction chamber and having the heating means interposed therebetween, and a diameter of the supply pipe downstream of the heating means relative to the supply pipe. 6. The apparatus for forming a silicon oxide film according to claim 4, wherein a narrow portion for reducing the diameter is provided. 7. The reaction chamber includes an inner tube for accommodating the object to be processed, and an outer tube having a ceiling formed to cover the inner tube. The apparatus for forming a silicon oxide film according to claim 4, wherein a supply unit is disposed so as to face the inside of the inner tube.