JP2001110797A - Method for forming nitride film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor manufacturing device suppressing a by- product (dust) in a reaction chamber, improving productivity and making a process condition and the like to be a minimum and to provide a thin-film forming method. SOLUTION: A constitution element (M) except for the nitrogen of a nitride film, reaction gas (M-N-H gas), constituted of nitrogen and hydrogen and ammonia, are used and the reaction gas is generated in a mixing chamber 503 installed on the front side of a reaction chamber 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to various nitride film forming methods using a semiconductor manufacturing apparatus for forming a thin film on a wafer surface using a reaction gas.

[0002]

2. Description of the Related Art FIG. 16 shows, for example, Japanese Patent Publication No. 60-10108.
FIG. 17 is a schematic configuration diagram showing a first conventional semiconductor manufacturing apparatus (so-called batch type) for implementing the method of forming a silicon nitride film disclosed in Japanese Patent Application Laid-Open Publication No. H10-209, FIG. It is a perspective view. 16 and 17, 1 is a semiconductor wafer, 2 is a reaction chamber, 4 is a wafer heating source, 501 and 50.
2 is a reaction gas supply pipe.

In the method of forming a thin film using this apparatus, a plurality of semiconductor wafers 1 to be processed are arranged and held in a tubular reaction chamber 2, and dichlorosilane and ammonia are flowed from reaction gas supply pipes 501 and 502 under reduced pressure. And a deposition temperature in the range of 650 to 800 ° C. is used.

[0004] In the above-mentioned method, in order to ensure uniformity of a film thickness and the like among a plurality of semiconductor wafers 1,
In order to compensate for the reduction in the deposition rate due to the consumption of the reaction gas, the semiconductor wafer 1 is moved from the upstream side to the downstream side of the gas.
The temperature distribution in the tubular reaction chamber 2 is controlled so that the temperature of the tubular reaction chamber 2 becomes higher. The pressure in the reaction chamber 2 is as low as about 0.5 Torr in order to ensure uniformity of the film thickness in the surface of the semiconductor wafer 1.

FIG. 19 shows, for example, Japanese Patent Application Laid-Open No. 54-160172.
FIG. 1 is a cross-sectional view showing a second conventional example of a semiconductor manufacturing apparatus disclosed in Japanese Unexamined Patent Application Publication No. Hei. In the figure, reference numeral 701 denotes a reaction vessel, which is
A reaction tube 3 is provided inside a tubular inner tube 702. Reference numeral 704 denotes a substrate support board disposed in the reaction space 3. The substrate support board 704 has a structure for supporting a large number of semiconductor wafers 1. Reference numeral 4 denotes a wafer heating source for heating the semiconductor wafer 1, and the wafer heating source 4 is provided on a peripheral wall of the reaction vessel 701.

[0006] Reference numeral 501 denotes a reaction gas
Chlorosilane (SiH_TwoCl_TwoReaction to introduce)
A gas supply pipe 502 is ammonia which is another reaction gas
(NH _Three) Into the reaction space 3.
It is a supply pipe. These reaction gas supply pipes 501 and 502
Are provided through the reaction vessel 701, respectively.
The upstream side of the stream is connected to a source material gas source (not shown)
At the same time, the downstream side is open to the lower part of the reaction chamber 2.

Reference numeral 7 denotes a reaction gas exhaust passage for discharging gas in the reaction vessel 701. This reaction gas exhaust path 7 is
One end of the inner tube 70 in the reaction vessel 701
An opening is formed in a space on the outer peripheral side of the second unit 2 and the other end is connected to an exhaust device (not shown). The pressure in the reaction vessel 701 is generally reduced by discharging the internal gas through the reaction gas exhaust path 7.

In the semiconductor manufacturing apparatus configured as described above, first, the reaction vessel 701 is
The semiconductor wafer 1 is heated through the peripheral wall. The temperature at this time is about 700 ° C. Next, dichlorosilane and ammonia were separately supplied to the reaction gas supply pipes 501 and 501.
From 502, it is introduced into the reaction space 3. The two kinds of reaction gases supplied into the reaction space 3 are thermally decomposed in a gas phase in contact with the heated semiconductor wafer 1. And
The resulting reaction product is deposited on the semiconductor wafer 1, and a silicon nitride film is formed.

FIG. 20 is a sectional view showing an outline of a third conventional semiconductor manufacturing apparatus (so-called single wafer type) disclosed in, for example, Japanese Patent Application Laid-Open No. 3-184327. In the figure, 1
Is a semiconductor wafer, 2 is a reaction chamber for housing the semiconductor wafer 1, 5 is a vacuum chuck for mounting the semiconductor wafer 1, 20
Reference numeral 4 denotes a vacuum evacuation hole opened in the vacuum chuck 5, 4 a wafer heating source built in the vacuum chuck 5 for heating the semiconductor wafer 1, 6 a gas nozzle for supplying a reaction gas to the reaction chamber 2,
Reference numeral 3 denotes a reaction space in which the reaction is performed, and reference numeral 7 denotes a reaction gas exhaust passage for exhausting the reacted gas in the reaction chamber 2.

In order to form a thin film by the semiconductor manufacturing apparatus having such a configuration, first, the semiconductor wafer 1 is transferred by a transfer device (not shown) and mounted on the vacuum chuck 5. Next, the evacuation hole 2 opened in the vacuum chuck 5
From step 04, vacuum evacuation is performed and the semiconductor wafer 1 is sucked. A reaction gas is supplied from the gas nozzle 6 into the reaction chamber 2. At this time, since the wafer 1 is heated by the wafer heating source 4 via the vacuum chuck 5, the reaction gas causes a thermochemical reaction on the semiconductor wafer 1 to form a thin film on the semiconductor wafer 1.

In the above process, the semiconductor wafer 1
Must be heated to a high temperature, for example, from 600 ° C. to 800 ° C. Further, the film quality and growth rate of the reaction product film depend on the temperature of the semiconductor wafer 1. In order to form the film quality and the film thickness of the reaction product film uniformly, the semiconductor wafer 1 is heated uniformly at a predetermined temperature. There is a need to. It is also necessary to prevent contamination of the wafer and the thin film formed on the wafer surface.

FIG. 21 is a sectional view showing a structure of a gas seal portion of a reaction chamber in a semiconductor manufacturing apparatus (a low-pressure CVD apparatus) of a fourth conventional example cited in, for example, JP-A-2-143526. In the same figure, 305 is an O-ring,
317 is a process tube, 318 is a cap, 319
Is a manifold, and 320 is the cap 318.
An inert gas supply hole 306 for introducing an inert gas (N ₂ ) into a gap portion between the manifold 319 and the process tube 317, the cap 318, and the gap between the manifold 319. Water cooling section.

In the above configuration, the process tube 3
The inside of the reaction tube 17 is kept at a high temperature, and the introduced reaction gas causes a thermochemical reaction on a wafer (not shown) in the process tube 317 to form a thin film. At this time, the O-ring 305
Has a role of a gas seal with the outside. In order to prevent damage due to heat and deterioration of the sealing function, water flows through the water cooling unit 306 to cool and protect the O-ring 305. As a result, the temperature around the O-ring 305 decreases, but by introducing an inert gas into this gap, the O-ring 30
In this way, the reaction gas is prevented from entering the vicinity of 5 to prevent the reaction by-products from adhering.

Here, conventionally, when a thin film for a semiconductor is formed by single-wafer type low-pressure CVD, for example, Japanese Patent Application Laid-Open No. 3-287770.
As shown in the publication, a nozzle head having a configuration having only a large number of through holes has been used in order to form a thin film having a uniform thickness by making the flow of the reaction gas uniform.

FIG. 22 is a cross-sectional view showing a reactive gas supply section in a conventional semiconductor manufacturing apparatus. FIG. 22 shows a case where two kinds of reactive gases are led to a heated wafer and subjected to decomposition reaction to form a film. . In the figure, 1 is a semiconductor wafer, 5
Is a susceptor, 4 is a wafer heating source, 604 is a first reaction gas, 605 is a second reaction gas, 606 is a mixed gas transport path, 6 is a gas nozzle, 3 is a reaction space, and 7 is a reaction gas exhaust path.

In this apparatus, for example, the first reactant gas 604 and the second reactant gas 605 are guided to the mixed gas transport path 606 by separate pipes, and then directed toward the semiconductor wafer 1 through the many through holes of the gas nozzle 6. It is injected and supplied. The semiconductor wafer 1 is placed on a susceptor 5 heated by a wafer heating source 4. The supplied reaction gas undergoes a decomposition reaction on the semiconductor wafer 1, and then a reaction gas exhaust path 7.
And are processed. In some cases, the gas nozzle 6 is provided so that the through-hole is provided orthogonal to the semiconductor wafer 1, or is provided at an angle of 20 to 45 ° toward the semiconductor wafer 1 as shown in FIG. 22.

[0017]

The semiconductor manufacturing apparatus for carrying out the conventional method of forming a nitride film is constructed as described above, so that the conventional batch type semiconductor described with reference to FIGS. The following problems have been encountered in the method of forming a nitride film by a manufacturing apparatus.

First, there is a problem in that by-products (mainly ammonium chloride) generated by the reaction between dichlorosilane and ammonia become dust sources, thereby significantly reducing the productivity of semiconductor chips.

Further, in order to suppress the production of ammonium chloride, the pressure in the reaction chamber 2 must be reduced to less than 1.0 Torr, and dichlorosilane and ammonia must be mixed in this atmosphere. In addition, in order to prevent ammonium chloride from adhering to the reaction chamber wall, the reaction chamber wall is heated to a high temperature (20.
(0 ° C. or more). That is, there is a problem that a process for forming a film is restricted, and a film cannot be formed with an appropriate apparatus configuration and optimum process conditions.

In addition, a capacitor film of a semiconductor or the like must have a very small thickness in order to secure the capacitor capacitance with a small area, and be formed in a complicated three-dimensional shape with a uniform thickness in order to secure a surface area. Is required. Also, in order to reduce the cost of the semiconductor, the semiconductor wafer 1 must be
Has a larger diameter. However, Japanese Patent Publication No. 60-1010
When a large-diameter wafer is processed by the method disclosed in Japanese Patent Application Laid-Open No. 8 (1994) -108, there is a problem that the film thickness distribution in the semiconductor wafer 1 increases.

In order to realize the film thickness with good reproducibility,
It is necessary to control the balance between the temperature of the wafer and the amount of the reaction gas, and the method disclosed in Japanese Patent Publication No.
That is, in the method using the batch type CVD apparatus, in order to suppress the variation in the film thickness of the plurality of semiconductor wafers 1, the temperature inside the tubular reaction chamber 2 is increased so that the wafer temperature increases from the upstream side to the downstream side of the gas. Although the temperature distribution is controlled, there is a limit in accuracy. Actually, the number of semiconductor wafers 1 to be processed at one time is reduced, and the remaining semiconductor wafers 1 called dummy wafers are used as substitutes. There has been a problem that the cost is reduced, that is, the cost is increased.

Further, in order to form an extremely thin film with good reproducibility, it is necessary to precisely control the properties of the underlying portion on which the capacitor film is to be formed. The technique disclosed in Japanese Patent Publication No. 60-10108 (so-called batch method) has a problem that this control cannot be performed.

[0023] Against this background, a CVD apparatus called a single-wafer type has been developed in recent years (shown in JP-A-3-184327) with reference to FIG. However,
When this single-wafer CVD apparatus is used, a conventional batch type C
In order to secure the same level of productivity as when using a VD device, the reaction chamber pressure is increased from 0.5 Torr to several tens to several tens
There was a problem that it was necessary to increase to Torr.

Also, ammonium chloride generated when dichlorosilane or titanium tetrachloride and ammonia are used as a reaction gas has a saturated vapor pressure characteristic as shown in FIG. If the wall temperature is not kept high, ammonium chloride solidifies and adheres. When the reaction chamber pressure was as low as 0.5 Torr, the wall temperature had only to be maintained at about 150 ° C. However, when the pressure in the reaction chamber is increased from several Torr to several tens of Torr, the wall temperature required to prevent solidification of ammonium chloride reaches 250 ° C., and a rubber vacuum sealing material (O-ring) usually used for vacuum holding is used. There is a problem that the film cannot be formed under an optimum process condition.

In a single wafer CVD system, a batch CVD system is used.
Since the structure is more complicated than that of the device, it is highly necessary to use a metal material such as SUS for the structural material. However, metal materials generally have a high risk of being corroded by chlorine at high temperatures, and have a problem that they are limited to expensive metal materials having high corrosion resistance such as Inconel and glass materials such as quartz.

Further, in the conventional single-wafer type semiconductor manufacturing apparatus shown in FIG. 21, since the high-temperature portion of the vacuum chuck 5 is exposed to the reaction gas, a film adheres to the high-temperature portion and causes dust. When the reaction gas is a corrosive gas, the high-temperature wafer heating source 4 is corroded and causes a failure. Further, since the high-temperature portion heated by the wafer heating source 4 is the same as the reaction space 3 in which the semiconductor wafer 1 is installed and the reaction is performed, the semiconductor wafer 1 from the wafer heating source 4 and the surrounding high-temperature portion is not heated. In addition, there is a problem that a thin film formed on the wafer surface is contaminated.

Further, since the wafer holding mechanism is the vacuum chuck 5, a vacuum layer is formed in the space between the semiconductor wafer 1 and the wafer holding mechanism, and the thermal resistance between the two becomes extremely large.
During film formation, the semiconductor wafer 1 is heated to a high temperature (for example,
(00 ° C.), the wafer heating source 4 had to be heated to a high temperature. Furthermore, when the heat generation distribution of the wafer heating source 4 varies, there is a problem that the temperature distribution of the semiconductor wafer 1 cannot be made uniform.

Next, in the conventional semiconductor manufacturing apparatus having a gas seal portion shown in FIG.
Under a reduced pressure of about several Torr as shown in Japanese Patent Publication No. 26, the effect of diffusion of the reaction gas becomes large, and it is necessary to introduce a large amount of inert gas in order to prevent this diffusion and prevent the invasion of the reaction gas. Becomes In addition, the inert gas is introduced into the reaction chamber from a narrow gap, and there is a problem that even a small amount of the reaction by-product is blown into the reaction chamber.

The supply structure of the reaction gas shown in FIG.
Then, for example, SiH_TwoCl_TwoAnd NH _ThreeAs a reaction gas
When forming a silicon nitride film by using
Is mixed only at room temperature and the reaction byproduct NH_FourCl (white
Color solids) to form two reactive gases
Are connected to a mixing location, particularly a mixed gas transport path 606.
SiH_TwoCl_TwoClogging of the piping outlet part of the
There is a problem that foreign matter adheres to the conductor wafer 1.

Further, the two kinds of reaction gases are mixed,
When a reactive gas is supplied onto the semiconductor wafer 1 through the gas nozzle 6 to form a thin film, there is a problem in uniformity of the film thickness. For example, FIG.
4 shows an example of data of a film thickness distribution in an inch wafer surface. The film forming conditions are as follows: total pressure is 30 Torr, SiH ₂ Cl ₂ flow rate / N
₂ diluted NH ₃ flow rate is respectively 10sccm / 550sc
cm dilution 40 sccm, wafer surface temperature 700 ° C. This data indicates that the in-plane film thickness distribution shows a one-sided pattern, and in particular, the film thickness of SiH ₂ Cl _{2 on} the pipe side is large.
It can be seen that the reaction gas of SiH ₂ Cl ₂ and NH ₃ is not sufficiently mixed uniformly.

The present invention has been made to solve the above-described problems, and can suppress the generation of by-products (dust) in the reaction chamber, increase the productivity, and reduce the process conditions and the like. It is an object to obtain a semiconductor manufacturing apparatus or a thin film forming method that can be optimized.

[0032]

According to the present invention, there is provided a nitride film forming method for forming a nitride film on a semiconductor wafer loaded in a reaction chamber by using a reaction gas.
Using a constituent gas (M) other than nitrogen of the nitride film, a reaction gas (M-N-H gas) composed of nitrogen and hydrogen, and ammonia, a new reaction gas is supplied in a mixing chamber provided in front of the reaction chamber. To generate.

The nitride film forming method according to the present invention is the nitride film forming method for forming a nitride film on a semiconductor wafer loaded in a reaction chamber by using a reaction gas, wherein the donor gas containing chlorine as a ligand and ammonia are used. Pre-mixing is performed in advance in a mixing chamber provided before the reaction chamber, a new reaction gas (a gas composed of MNxHy) is generated and transported to the reaction chamber, and by-products such as ammonium chloride are removed from the reaction chamber. It is trapped in the mixing chamber and transported to the reaction chamber.

In the method of forming a nitride film according to the present invention, the temperature of the mixing chamber is set at a certain temperature T1 of 30 ° C. or more and 180 ° C. or less.

In the method of forming a nitride film according to the present invention, when the reaction chamber pressure P2 is used at 20 Torr or less, the pressure P1 of the mixing chamber is set to P1> 20 To regardless of the pressure P2 of the reaction chamber.
It is set to rr.

The method for forming a nitride film according to the present invention is configured such that the temperature of the mixing chamber is set at the temperature T1, and the gas contact wall surface from the mixing chamber to the trap chamber is maintained at a temperature equal to or higher than the temperature T1. .

In the nitride film forming method according to the present invention, the mixing chamber is composed of two chambers, and one of the two chambers on the gas introduction side is set to a temperature T3 of 200 ° C. or more. It is.

In the method of forming a nitride film according to the present invention, dichlorosilane (SiH ₂ Cl ₂ ) and ammonia are used as the reaction gas.

In the method of forming a nitride film according to the present invention, titanium tetrachloride (TiCl ₄ ) and ammonia (N
H ₃ ) and hydrogen (H ₂ ).

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a cross-sectional view showing a schematic configuration of a semiconductor device for performing a nitride film forming method according to a first embodiment of the present invention. In the figure, 1 is a semiconductor wafer, 2 is a reaction chamber for housing the semiconductor wafer 1, 3 is a reaction space, 4 is a wafer heating source for heating the semiconductor wafer 1, 5 is a vacuum chuck for mounting the semiconductor wafer 1, Reference numeral 6 denotes a gas nozzle for supplying a reaction gas to the reaction chamber 2, reference numeral 7 denotes a reaction gas exhaust path, reference numeral 8 denotes a vacuum chuck exhaust path, and reference numeral 9 denotes a latter stage for removing a reaction by-product from the reacted gas passing through the reaction gas exhaust path 7. It is a trap.

Next, the operation will be described. After the semiconductor wafer 1 is mounted on the vacuum chuck 5, the semiconductor wafer 1 is evacuated from a vacuum chuck exhaust path 8 opened to the vacuum chuck 5,
Adsorption is fixed by the pressure difference from the reaction space 3. Further, the semiconductor wafer 1 is heated to a high temperature by a wafer heating source 4 via a vacuum chuck 5. Gas nozzle 6
When a reaction gas is supplied into the reaction chamber 2 from above, a thin film is formed on the surface of the semiconductor wafer 1 at a high temperature by a thermochemical reaction. On the other hand, the reacted gas is supplied to the reaction gas exhaust passage 7.
, And is then exhausted after removing reaction by-products therefrom.

FIG. 2 is a cross-sectional view showing a main part of a semiconductor manufacturing apparatus for performing the nitride film forming method according to the first embodiment of the present invention, which is similar to (or equivalent to) the conventional apparatus shown in FIG. Constituent elements are given the same reference numerals and description thereof is omitted. In FIG. 2, a mixing chamber 503 and a heater 507 for the mixing chamber for covering the mixing chamber 503 and heating it to a reaction temperature.
And a pressure gauge 715 for monitoring the pressure of the mixing chamber.

Reference numeral 716 denotes a mixed gas supply pipe for sending the mixed gas from the mixing chamber 503 to the reaction space 3, and the mixed gas supply pipe 716 is provided with a pressure regulating valve 511. That is, the mixing chamber 503 is communicated with the reaction space 3 in the reaction chamber 2 via the mixed gas supply pipe 716 and the pressure regulating valve 511. Also, the mixing chamber 503
Are connected to reaction gas supply pipes 501 and 502.
The gas outlets of the reaction gas supply pipes 501 and 502 open to the lower part of the mixing chamber 503, respectively.

The collision plate 512 is provided in the mixing chamber 503.
Are arranged at intervals to form a reversible passage from the lower part to the upper part of the mixing chamber 503.

Next, the operation will be described. First, the temperature and pressure required for film formation in the reaction space 3 in which the semiconductor wafer 1 is disposed are increased, and the temperature in the mixing chamber 503 is increased to a temperature at which reaction gases react with each other. Then, the reaction gases dichlorosilane and ammonia are supplied to the reaction gas supply pipe 50.
The mixture is introduced into the mixing chamber 503 through the ports 1 and 502.

In this way, a gas flow is generated from the lower part of the mixing chamber 503 to the upper part through the reversing passage. Then, the reaction gases are mixed and reacted in the mixing chamber 503 to generate ammonium chloride which is a source of dust. The ammonium chloride is solidified in the mixing chamber 503 and rides on the gas flow, passes through an inverting passage in the mixing chamber 503, and adheres to the collision plate 512. That is, only the mixed gas after the ammonium chloride is collected by the collision plate 512 is supplied from the mixing chamber 503 to the reaction space 3 through the mixed gas supply pipe 716 and the pressure regulating valve 511.

Then, the mixed gas is introduced into the reaction space 3 from the mixing chamber 503, so that the semiconductor wafer 1
A silicon nitride film is formed in the reaction space 3 as described above, since this mixed gas is mainly reformed into an ammonia and silylamine (SiNxHy).
It is possible to set the temperature of the reaction chamber wall (the wall of the reaction vessel 2) lower than that of the conventional apparatus while reducing the amount of dust in the reaction chamber, and the pressure in the reaction space 3 to be higher than before. Process conditions can be set to optimal conditions.

Embodiment 2 FIG. 3 is a sectional view showing a main part of a semiconductor manufacturing apparatus for performing a nitride film forming method according to a second embodiment of the present invention. In FIG.
Is an aggregating device for aggregating by-products (ammonium chloride) generated in the mixing chamber 503. This aggregating device 721
Is composed of an ultrasonic generator in this case, and is fixed to the bottom of the mixing chamber 503 in close contact.

As described above, the aggregating device 721 is connected to the mixing chamber 503.
In this embodiment, the ammonium chloride particles generated in the mixing chamber 503 are aggregated with each other and the particle size increases, so that ammonium chloride can be efficiently collected.

Embodiment 3 FIG. 4 is a sectional view showing a main part of a semiconductor manufacturing apparatus for performing a nitride film forming method according to a third embodiment of the present invention. In FIG.
Is a bypass pipe that bypasses the reaction space 3 and communicates the mixed gas supply pipe 716 and the reaction gas exhaust path 7. One end of the bypass pipe 722 is connected to the mixed gas supply pipe 716 via the three-way valve 723, and the other end is connected to the reaction gas exhaust path 7. The three-way valve 723 has a conventionally well-known structure in which the mixed gas flowing out of the mixing chamber 503 is selectively passed to the reaction space 3 and the bypass pipe 722.

With this configuration, the ammonium chloride deposited in the mixing chamber 503 is discharged to the exhaust system via the three-way valve 723 and the bypass pipe 722, and is collected by the collection device 718.
Function can be reproduced. That is, when the flow rate of the mixed gas decreases due to the deposition of ammonium chloride,
The bus of the three-way valve 723 is switched to the bypass pipe 722 side.
Heat above 00 ° C. As a result, the ammonium chloride is sublimated and discharged out of the device by an exhaust device (exhaust pump). Therefore, the by-product collection function can be maintained in the mixing chamber 503 for a long time.

Embodiment 4 FIG. FIG. 5 is a sectional view showing a main part of a semiconductor manufacturing apparatus for performing a nitride film forming method according to a fourth embodiment of the present invention. In FIG.
Is a gas retention tank. Further, the downstream end of the mixed gas supply pipe 716 is opened at a lower part of the gas retention tank 724.
The upper part of the gas storage tank 724 communicates with the reaction space 3 via the communication pipe 726.

As described above, the gas retention tank 724 is connected to the reaction space 3.
When it is interposed between and the mixing chamber 503, the fine particulate ammonium chloride that could not be collected is settled and removed in the gas retention tank 724. Therefore, ammonium chloride hardly flows into the reaction space 3, and a high-quality reaction atmosphere with less dust can be obtained.

Embodiment 5 FIG. FIG. 6 is a sectional view showing a main part of a semiconductor manufacturing apparatus for performing a nitride film forming method according to a fifth embodiment of the present invention. In FIG.
And 502 are reaction gas supply pipes, 503 is a mixing chamber provided in front of the reaction chamber 2, 507 is a heater for the mixing chamber, 50
8 is a reaction chamber wall heater, 509 is a water cooling mechanism, and 511 is a pressure regulating valve provided in a pipe connecting the reaction chamber 2 and the mixing chamber 503.

In the method of forming a nitride film by the semiconductor manufacturing apparatus of the fifth embodiment, the mixing chamber 50
The temperature of the reaction chamber 2 is maintained at a low temperature, for example, about 20 ° C.
The reaction is performed by flowing a reaction gas, for example, dichlorosilane (SiH ₂ Cl ₂ ) and ammonia (NH ₃ ) from the reaction gas supply pipes 501 and 502 while maintaining the pressure at a predetermined processing pressure (normally 1 to 100 Torr).

Then, these gases react in the mixing chamber 503 to generate ammonium chloride (NH ₄ Cl) and a Si—N—H compound. Most of the ammonium chloride is solidified in the mixing chamber 503, and only the gas mainly containing the Si—N—H compound is sent to the reaction chamber 2 to be heated on the wafer 1 heated by the wafer heating source 4 or the reaction space 3. To form a high-purity SiN film on the wafer 1. Therefore, even if the walls of the reaction chamber 2 are not heated to a high temperature, ammonium chloride does not adhere to the inside of the reaction chamber 2 and the reaction chamber 2 is made of an expensive material that is not likely to be corroded by chlorine. You don't have to.

That is, as can be seen from the saturated vapor pressure diagram of FIG. 18, ammonium chloride exists in a gas state only at a pressure of about 1 × 10 ⁻⁴ Torr at a low temperature of about 20 ° C. That is, a reaction chamber pressure of 1 to 1 usually used in a single wafer system
At 00 Torr, almost no gas can exist and the mixing chamber 5
It solidifies within 03. However, most of the Si—N—H compound exists in a gas state even under these conditions, and is transported to the reaction chamber 2.

FIG. 7 shows a reaction chamber pressure of 30 To
It is the result of analyzing the composition of the SiN film formed under the condition of rr by Auger electron spectroscopy. As can be seen from FIG. 7, a high-quality SiN film containing no impurities such as chlorine is formed. The refractive index of this film was evaluated by ellipsometry, and the result was 1.98.
It was comparable to the i ₃ N ₄ film. On the other hand, FIG.
The result of x-ray diffraction of the white solid deposited on 03 shows that most is ammonium chloride (NH ₄ Cl).

The Si—N—H compound produced here is composed of SiNH ₅ , SiN ₂ H ₆ , SiN ₃ H ₇ ,
It is a simple substance or a mixture of N ₄ H ₈ , and this product may be separately prepared and stored, and used as a raw material. If the purification is insufficient, for example, SiNH ₄ Cl, SiNH ₆
Cl, SiN ₂ H ₇ Cl _{2 and the} like may be mixed.

Embodiment 6 FIG. The method of forming a nitride film according to the sixth embodiment differs from the method of the fifth embodiment using the apparatus shown in FIG.
The thin film is formed while the temperature is maintained at a certain constant temperature of, for example, about 100 ° C. (T1). According to this nitride film forming method, the stable Si in a gas state in the mixing chamber 503 is obtained.
The -NH compound is generated, and the thickness reproducibility of the formed film is improved.

That is, as can be seen from the measurement result of the change in the heating weight shown in FIG. 9, the white solid matter generated in the mixing chamber 503 by the method of Embodiment 5 was heated to 300 ° C. About 20% of solids that do not evaporate. Investigation by infrared spectroscopy shows that the remaining solid is a Si compound. However, as can be seen from the measurement result of the change in the heating weight shown in FIG.
The white solid produced in No. 3 gasified when heated to 300 ° C., and no solid remained.

That is, by mixing while slightly heating, the reaction between SiH ₂ Cl ₂ and NH ₃ is promoted, and a stable Si—N—H compound can be formed in a gaseous state. The characteristics of the SiN film manufactured under these conditions are the same as those of the fifth embodiment. However, in the fifth embodiment, the reproducibility of the film thickness is not so good. In this embodiment, it was possible to suppress the variation to ± 1% or less.

Embodiment 7 FIG. When the temperature of the mixing chamber 503 is increased as in the sixth embodiment, the pressure of NH ₄ Cl, which can be present as a gas, increases, and more NH ₄ Cl is NH ₃ Cl than when the mixing chamber temperature is 20 ° C. It flows into the reaction chamber in the form of ₃ + HCl, and NH ₄ Cl adheres to the reaction chamber wall. Therefore, in the seventh embodiment, in the apparatus shown in FIG. 6, while maintaining the reaction chamber wall temperature at the temperature T1 by using the heater 508, the rear trap 9 provided on the exhaust side of the reaction chamber 2 by the water cooling mechanism 509 is used. The processing is performed while keeping the inner wall of the substrate at 30 ° C. or lower.

Then, the NH ₄ flowing from the mixing chamber 503
Cl is transported to the subsequent trap 9 without solidifying in the reaction chamber 2 and solidified in the latter trap 9. That is, while slightly raising the temperature of the mixing chamber 503, it is possible to almost completely prevent NH ₄ Cl adhesion in the reaction chamber. Even if the film is formed, there is obtained an effect that NH ₄ Cl does not scatter on the substrate and adversely affect the film quality.
Since the temperature T1 is 180 ° C. or less, even if this heating is performed, an O-ring material can be used for the vacuum seal as in the past, and the reaction chamber 2 is an expensive material that is not likely to be corroded by chlorine. There is no need to configure it.

Embodiment 8 FIG. In the fifth embodiment, for example, when the processing pressure P2 in the reaction chamber 2 is relatively low, such as about 3 Torr, when the pressure in the mixing chamber 503 is maintained at substantially the same pressure as the pressure in the reaction chamber 2, the gas pressure in the mixing chamber 503 is reduced. The collision probability decreases, and it becomes impossible to generate a sufficient Si—N—H compound. Therefore, in the eighth embodiment, in the nitride film forming method of the fifth embodiment, the pressure regulating valve 511 in the apparatus of FIG. 6 is operated to maintain the pressure P1 of the mixing chamber 503 at 20 Torr or more, for example, 30 Torr. To perform a thin film forming process.

According to the nitride film forming method of the eighth embodiment, even when the processing pressure P2 in the reaction chamber 2 is low, many gas collisions can occur in the mixing chamber, and sufficient Si
The formation of -NH compound becomes possible. Therefore, even when the reaction chamber pressure is relatively low, it is possible to form a SiN film having a stable film thickness and the like.

Embodiment 9 In the fifth embodiment, for example, in order to improve the purity of the manufactured SiN film, it is necessary to sufficiently remove the Si—Cl bond. In addition, for example, in order to improve the coverage of a formed film on a three-dimensional shape, it is necessary to remove a film-forming precursor that is highly reactive and easily adheres.

Therefore, in the ninth embodiment, as shown in FIG. 11, the mixing chamber in the apparatus shown in FIG.
a and a low-temperature chamber 503b, the high-temperature mixing chamber heater 507a sets the high-temperature chamber 503a to a temperature of 200 ° C. or higher, and the low-temperature mixing chamber heater 507b sets the low-temperature chamber 503b to a temperature of 180 ° C. or lower. Set and perform processing.

In this way, the reaction gas and ammonia are sufficiently mixed in the high-temperature chamber 503a and react rapidly, producing a Si-N-H compound near 100%. On the other hand, in the low-temperature chamber 503b, a very small amount of a reactive substance or the like which remains is removed by trapping. Therefore, in the reaction in the reaction chamber 2, an extremely high-purity thin film having good throwing power is produced, and the above-described Embodiments 5 and 6 are used.
And the like, and the effect of the above is also maintained.

FIG. 12 shows the temperature 250 of the high temperature chamber 503a.
℃, low temperature chamber 503b temperature 150 ℃, reaction chamber pressure 3 Torr
7 is a drawing of a cross-sectional photograph showing a result of depositing a SiN film on a minute hole of the SiN film prepared in Step (a). Even at the bottom of the minute hole, a deposition amount of 97% or more of the surface can be secured. Further, as a result of examining the impurities of this film, it was found that chlorine (Cl) and the like were not contained even in an extremely sensitive SIMS analysis.

Tenth Embodiment FIG. 13 is a structural diagram showing an example of the internal structure of a mixing chamber 503 used in the fifth to eighth embodiments. In the figure, 512
Are large collision plates, 513 and 515 are perforated plates, 51
Reference numeral 4 denotes a trap unit, and 516 denotes a gas outlet.

In this mixing chamber, the reaction gas supply pipe 50
The reaction gas introduced from 1,502 diffuses while hitting the collision plate 512 with a large interval, and passes through the perforated plate 513 into the trap portion 514 where a large number of collision plates are densely packed. In the trap portion 514, the gas hits the collision plate in a zigzag manner, proceeds to the porous plate 515 while solidifying ammonium chloride, reaches the gas outlet 516 with the ammonium chloride removed, and is transported to the reaction chamber 2. The temperature of the mixing chamber 503 is controlled by the mantle heater 50 which is heated from the outer periphery.
The temperature is controlled by 7 (mixer chamber heater).

Embodiment 11 FIG. FIG. 14 is a structural diagram showing an example of the internal structure of the mixing chamber 503 used in the eleventh embodiment. The difference from the mixing chamber shown in FIG. 13 lies in the gas inlet. That is, in FIG. 14, reference numeral 517 denotes a mixing section (1 which constitutes a mixing chamber) provided in the gas introduction section.
(Room) 518 is a heater for heating the mixing section.

In this mixing chamber, the reaction gas supply pipes 501,
The reaction gas introduced from 502 is first mixed in the mixing section 51.
7. Mix well. At this time, the mixing unit 517
Since the heater 518 can be heated to 200 ° C. or more independently of the mixing chamber heater 507, the ninth embodiment can be used.
The same effect as described above is achieved.

Embodiment 12 FIG. FIG. 15 shows an example of the entire internal structure of the system shown in the fifth to eleventh embodiments. In the figure, reference numeral 503 denotes the mixing chamber 521 described in Embodiment 11 shown in FIG.
Is a transportation pipe connecting the gas outlet of the mixing chamber 503 to the gas nozzle 6, 519 is a mixing chamber pressure gauge for measuring the pressure in the mixing chamber 503, and 520 is a piping heater for heating the transportation pipe 521. Reference numeral 9 denotes the latter-stage trap, reference numeral 523 denotes a cooling perforated plate, and reference numeral 524 denotes a cooling collision plate.

In this apparatus, the pressure of the mixing chamber 503 can be controlled to a desired value independently of the reaction chamber 2 by using the pressure regulating valve 511 and the pressure gauge 519. The transport pipe 521 is provided with a pipe heater 52 so that ammonium chloride does not accumulate.
At 0, the temperature can be controlled to be several degrees higher than the mixing chamber 503.

Then, the transported gas passes through the gas nozzle 6, and the susceptor 51 heated by the wafer heating source 4.
Is uniformly sprayed on the wafer 1 placed in the above, and a nitride film is deposited. The gas after the reaction and the gas that has not reacted completely enter the latter trap 9 through the reaction gas exhaust path 7.
In the latter trap 9, the remaining ammonium chloride is solidified and removed by passing the gas through the cooling porous plate 523 and the cooling collision plate 524 cooled by the water cooling mechanism. This trap mechanism is the same as that of the ammonium chloride trap shown in FIG. 13. However, since the cooling perforated plate 523 and the cooling collision plate 524 kept at a low temperature of 30 ° C. or less by water cooling are used, it can be seen from FIG. In addition, the exhaust gas passing through the latter-stage trap 9 contains almost no ammonium chloride. In the twelfth embodiment, the mixing chamber 50
Although the structure of FIG. 14 is used in FIG. 3, the structure of FIG. 13 may be used.

[0078]

As described above, according to the present invention, the reaction gas (M-N-H gas) and ammonia react in the mixing chamber to produce by-products, and the by-products are removed in the reaction chamber. The supplied mixed gas is supplied. For this reason, the partial pressure of by-products in the reaction chamber is kept extremely low, and it is not necessary to set the temperature of the reaction chamber wall temperature high to suppress solidification and adhesion of by-products. Inexpensive and easily processed metal materials can be used. Therefore, there is an effect that the quality of the semiconductor can be improved and the production cost can be reduced.

[0079] According to the present invention, react donor gas and ammonia advance in the mixing chamber, by-products are trapped in the mixing chamber, the new reaction gas (MN _x gas composed of H _y) are generated react Transported to the room. For this reason, the partial pressure of the by-product in the reaction chamber is kept extremely low, and it is not necessary to set the temperature of the reaction chamber wall temperature high in order to suppress solidification and adhesion of the by-product. Inexpensive and easily processed metal materials can be used. Therefore,
There is an effect that the quality of the semiconductor can be improved and the production cost can be reduced.

According to the present invention, since the temperatures of the mixing chamber and the reaction chamber are set at a certain temperature T1 of 30 ° C. or more and 180 ° C. or less, the Si—N—
An H compound is generated, and the thickness reproducibility of the formed film is improved. Therefore, there is an effect that the quality of the semiconductor can be further improved.

According to the present invention, a pressure regulating valve is provided between the mixing chamber and the reaction chamber so that the pressure in the mixing chamber and the pressure in the reaction chamber can be controlled independently, and when the reaction chamber pressure P2 is used at 20 Torr or less. Since the pressure P1 in the mixing chamber is set to P1> 20 Torr regardless of the pressure P2 in the reaction chamber, the processing pressure P
Even when 2 is low, many gas collisions can occur in the mixing chamber, and sufficient generation of Si-N-H compounds becomes possible. Therefore, even when the reaction chamber pressure is relatively low, it is possible to form a SiN film having a stable film thickness and the like. Therefore, there is an effect that the quality of the semiconductor can be further improved.

According to the present invention, a trap chamber having a gas contact wall surface whose temperature is controlled to 30 ° C. or less is provided after the reaction chamber, the temperature of the mixing chamber is set to T1, and the contact between the mixing chamber and the trap chamber is established. Since the gas wall surface is maintained at a temperature equal to or higher than T1, by-products that cannot be completely trapped in the mixing chamber are not solidified in the reaction chamber but are collected in the trap chamber after the reaction chamber. Therefore, further improvement of the quality of the formed thin film,
As a result, there is an effect that the quality of the semiconductor can be further improved.

According to the present invention, the mixing chamber is composed of two chambers, and the temperature on the gas introduction side is set to the temperature T3 of 200 ° C. or higher. Are produced and transported to the reaction chamber, while by-products are collected in two of the mixing chambers. Therefore, there is an effect that the quality of the formed thin film can be further improved, and the quality of the semiconductor can be further improved.

According to the present invention, since dichlorosilane (SiH ₂ Cl ₂ ) and ammonia are used as the reaction gas, by-products are easily generated, and the effect of improving the quality of the semiconductor becomes more remarkable. is there.

According to the present invention, since titanium tetrachloride (TiC ₁₄ ), ammonia (NH ₃ ), and hydrogen (H ₂ ) are used as the reaction gas, by-products are easily generated, and the quality of the semiconductor is improved. There is an effect that the effect becomes more remarkable.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration of a semiconductor device for performing a nitride film forming method according to a first embodiment of the present invention;

FIG. 2 is a sectional view showing a main part of a semiconductor manufacturing apparatus for performing a nitride film forming method according to the first embodiment of the present invention;

FIG. 3 is a sectional view showing a main part of a semiconductor manufacturing apparatus for performing a nitride film forming method according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing a main part of a semiconductor manufacturing apparatus for performing a nitride film forming method according to a third embodiment of the present invention.

FIG. 5 is a sectional view showing a main part of a semiconductor manufacturing apparatus for performing a nitride film forming method according to a fourth embodiment of the present invention.

FIG. 6 is a sectional view showing a main part of a semiconductor manufacturing apparatus for performing a nitride film forming method according to a fifth embodiment of the present invention.

FIG. 7 is a diagram showing a composition analysis result of a silicon nitride film formed by the nitride film forming method according to the embodiment of the present invention.

FIG. 8 is a diagram showing an X-ray analysis result of a solid deposited in a mixing chamber when a silicon nitride film is formed by the nitride film forming method according to the embodiment of the present invention.

FIG. 9 is a view showing a thermogravimetric change measurement result of a solid deposited in a mixing chamber when a silicon nitride film is formed by the nitride film forming method according to the embodiment of the present invention.

FIG. 10 is a diagram showing a thermogravimetric change measurement result of a solid deposited in a mixing chamber when a silicon nitride film is formed by the nitride film forming method according to the embodiment of the present invention.

FIG. 11 is a sectional view showing a mixing chamber of a semiconductor manufacturing apparatus used in the nitride film forming method according to the embodiment of the present invention;

FIG. 12 is a cross-sectional view showing a situation in which a silicon nitride film formed by a nitride film forming method according to an embodiment of the present invention is deposited on minute holes.

FIG. 13 is a structural diagram showing an example of an internal structure of a mixing chamber used in the nitride film forming method according to the embodiment of the present invention.

FIG. 14 is a structural diagram showing an example of an internal structure of a mixing chamber used in the nitride film forming method according to the embodiment of the present invention.

FIG. 15 is a diagram showing an example of the internal structure of the entire semiconductor manufacturing apparatus used in the nitride film forming method according to the embodiment of the present invention.

FIG. 16 is a schematic configuration diagram showing a semiconductor manufacturing apparatus (a so-called batch type) of a first conventional example.

FIG. 17 is a perspective view showing the reaction chamber in FIG. 16 with a part cut away.

FIG. 18 is a saturated vapor pressure diagram of ammonium chloride (NH ₄ Cl).

FIG. 19 is a sectional view showing a semiconductor manufacturing apparatus of a second conventional example.

FIG. 20 is a sectional view showing an outline of a semiconductor manufacturing apparatus (so-called single wafer type) of a third conventional example.

FIG. 21 shows a fourth conventional semiconductor manufacturing apparatus (low-pressure CVD).
FIG. 4 is a cross-sectional view illustrating a structure of a gas seal portion of a reaction chamber in the apparatus.

FIG. 22 is a sectional view showing a reaction gas supply unit in a conventional semiconductor manufacturing apparatus.

FIG. 23 is a view showing a measurement result of a film thickness distribution of a silicon nitride film formed on a 6-inch wafer by a conventional semiconductor manufacturing apparatus.

[Explanation of symbols]

Reference Signs List 1 semiconductor wafer, 2 reaction chamber, 3 reaction space, 4 wafer heating source, 5 partition member (vacuum chuck), 6 gas nozzle, 9 post-trap, 501, 502 reaction gas supply pipe, 503 mixing chamber, 503a high temperature chamber, 507
Heater for mixing chamber, 507a heater for high-temperature mixing chamber, 50
7b Low temperature mixing chamber heater, 508 reaction chamber wall heater, 509 water cooling mechanism, 511 pressure regulating valve, 512
Collision plate, 513, 515 perforated plate, 514 trap portion, 516 gas outlet, 517 mixing portion, 5
18 Heater, 520 Pipe heater, 523
Cooling perforated plate, 524 cooling impingement plate, 715 pressure gauge, 716 mixed gas supply pipe, 718 collection device, 72
1 coagulation device, 722 bypass pipe, 723 three-way valve,
724 Gas retention tank.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Katsuhisa Kitano 8-1-1, Tsukaguchi-Honcho, Amagasaki-shi Mitsubishi Electric Corporation Production Technology Laboratory (72) Inventor Kazuo Yoshida 8-1-1, Tsukaguchi-Honcho, Amagasaki-shi Mitsubishi Inside Electric Industrial Research Institute (72) Inventor Hiroshi Onishi 8-1-1 Tsukaguchi Honcho, Amagasaki City Mitsubishi Electric Corporation Inside Production Research Laboratory (72) Inventor Kenichiro Yamanishi 8-1-1 Tsukaguchi Honcho Amagasaki Mitsubishi (72) Inventor Shigeo Sasaki 2-3-2 Marunouchi, Chiyoda-ku, Tokyo In-house Mitsubishi Electric Corporation (72) Hideki Komori 8-1-1 Honcho Tsukaguchi, Amagasaki City Mitsubishi Electric Corporation (72) Inventor Taizo Ejima 1-1-1, Imajukuhigashi, Nishi-ku, Fukuoka City Mitsubishi Electric Corporation (72) Koichiro Tatsuhara, Inventor 4-1-1 Mizuhara, Itami City Mitsubishi Electric Corporation Inside Kita Itami Works, Ltd. (72) Toshihiko Noguchi 1-1-1, Imajuku Higashi, Nishi-ku, Fukuoka Mitsubishi Electric Machinery Co., Ltd. (72) Inventor, Takashi Takahama 8-1-1, Tsukaguchi-Honmachi, Amagasaki-shi Mitsubishi Electric Corporation Production Technology Laboratory (72) Inventor Yoshihiko Kusaba 8-1-1, Tsukaguchi-Honcho, Amagasaki-shi Mitsubishi Electric Corporation Inside the Institute of Industrial Science (72) Inventor Takeshi Iwamoto 8-1-1 Tsukaguchi Honcho, Amagasaki City Mitsubishi Electric Corporation Inside the Institute of Industrial Science (72) Inventor Noriyuki Kosaka 8-1-1 Honcho Tsukaguchi, Amagasaki City Mitsubishi Electric Corporation Inside the Production Engineering Laboratory

Claims (8)

[Claims] In a nitride film forming method for forming a nitride film on a semiconductor wafer loaded in a reaction chamber by using a reaction gas, a reaction comprising nitrogen and hydrogen, a constituent element (M) other than nitrogen of the nitride film. A method for forming a nitride film, comprising using a gas (M-N-H gas) and ammonia to generate the reaction gas in a mixing chamber provided in front of the reaction chamber. 2. A nitride film forming method for forming a nitride film on a semiconductor wafer loaded in a reaction chamber using a reaction gas, wherein a donor gas containing chlorine as a ligand and ammonia are mixed in a mixing chamber provided in front of the reaction chamber. Premixed in advance,
A new reaction gas (a gas composed of MNxHy) is generated and transported to the reaction chamber, and by-products such as ammonium chloride are trapped in the mixing chamber to prevent the reaction product from being transported to the reaction chamber. A method for forming a nitride film. 3. The temperature of the mixing chamber is 30 ° C. or more and 180 ° C.
3. The method for forming a nitride film according to claim 2, wherein the temperature is set to a certain constant temperature T1 described below. 4. When the reaction chamber pressure P2 is used at 20 Torr or less, the pressure P1 of the mixing chamber is changed to the pressure P of the reaction chamber.
4. The method according to claim 3, wherein P1> 20 Torr is set irrespective of 2. 5. The temperature of the mixing chamber is set to T1.
The gas contacting wall surface from the mixing chamber to the trap chamber is set at T1.
3. The method according to claim 2, wherein the temperature is maintained at the above temperature. 6. The mixing chamber is composed of two chambers, and one of the two chambers on the gas introduction side has a temperature T of 200 ° C. or higher.
3. The method for forming a nitride film according to claim 2, wherein the value is set to 3. 7. The reaction gas includes dichlorosilane (SiH
_{3. The} method according to claim _{2, wherein 2} Cl ₂ ) and ammonia are used. 8. The method according to claim 1, wherein the reaction gas is titanium tetrachloride (TiCl
_{4. The} method according to claim 2, wherein the method comprises using ammonia (NH ₃ ) and hydrogen (H ₂ ).