JP4899958B2 - Film forming method and film forming apparatus - Google Patents

Description

  The present invention relates to a film forming method and a film forming apparatus applied to semiconductor manufacturing and the like, and more particularly to a film forming method and a film forming apparatus for forming a semiconductor film having excellent uniformity in film thickness and composition ratio. .

Compound semiconductors such as InP and GaAs are used as materials for high-frequency devices and light-emitting elements. These compound semiconductors need to be formed on a substrate with a uniform thickness, and conventionally, a technology for uniformizing the film thickness has been actively developed. Here, in a horizontal apparatus often seen as a structure for mass production of semiconductor thin films, a source gas is introduced into a reaction chamber from a substantially horizontal direction with respect to a substrate, and a film is formed on the substrate through a chemical reaction. The conventional film thickness uniformization technique is shown below.
(1) In the method of controlling the source gas temperature by cooling the substrate facing side (Patent Document 1), the source gas temperature on the substrate is made uniform by providing a uniform or approximately 10 ° C. gradient. (2) In the method of cooling the substrate facing side and suppressing excessive material consumption in the upstream part (Patent Document 2), a temperature difference of about 400 ° C. is provided between the substrate surface and the substrate facing surface, and the source gas is thermally diffused. Use the phenomenon.
(3) A method of stabilizing the growth rate on the substrate by shifting the rapid film formation position onto the predeposition board by the predeposition board placed on the upstream side of the substrate.

On the other hand, the production volume of GaN, which has many excellent physical properties such as wide band gap, large thermal conductivity and high electron saturation rate, is increasing, and its mass production technology has been actively developed. Yes. Even in this case, the uniformity of the film thickness is an important issue, but it is difficult to achieve a high in-plane film thickness uniformity of GaN in the conventional techniques (1) and (2).
For this reason, the prior art (3), speeding up of the raw material gas flow rate, and the like are performed on the GaN film. However, these methods cause deterioration of the raw material utilization efficiency due to an increase in the amount of film formation outside the substrate and an increase in the amount of raw material gas flowing out of the apparatus.

  In Patent Document 1, it is disclosed that a plurality of coolant channels are provided on the outer periphery of the reaction furnace, and the temperature or flow rate of the coolant is changed for each channel to uniform the film thickness, composition, impurity concentration, and the like. ing. The basic idea in this technique is to make the source gas temperature substantially uniform on the substrate. However, Patent Document 1 also describes that the source gas temperature need not be uniform.

  In patent document 2, the technique which installs a heat conductor between the cooling jacket attached to the exterior of reaction container, and a reaction container outer wall or an opposing board is disclosed. Specifically, it is described that the temperature of the reaction vessel is partially adjusted by changing the thickness of the heat conductor.

  In Patent Document 3, a plurality of heating mechanisms for heating a plurality of portions of the workpiece to different temperatures are provided. It is not easy to accurately control the substrate temperature in the reaction furnace with the heating device, accompanied by radiation in the reaction vessel.

  In Patent Document 4, it is disclosed that a cooling unit capable of controlling the temperature is provided on the mask of the flow channel on the upstream side of the susceptor of the reaction vessel. The aim of this technique is to prevent the deposition of thin films on the flow channel ceiling.

  In Patent Document 5, a first heating means for heating the flow channel on the upstream side of the reaction vessel and a second heating means for heating the substrate are provided. The temperature of the first heating unit is set lower than the temperature of the second heating means. The point in this technique is that an appropriate gas phase temperature is set before the reactive species reach the substrate surface.

JP-A-4-132213 JP 2004-281836 A JP 2001-23975 A JP 2000-100726 A JP-A-11-74202

  Therefore, we repeatedly investigated the cause of the difficulty in making the GaN film thickness uniform, and found that the film formation reaction and the temperature on the substrate were the cause. The film formation reaction of GaN takes the path of “source gas → intermediate → film formation”. The same can be said for InP and GaAs. However, the film formation conditions for InP and GaAs are substantially the same as the intermediate generation start temperature, the film formation start temperature, and the substrate temperature. For this reason, in InP and GaAs, the source gas is gradually changed into an intermediate and film formation is performed. Since the processing temperature and the film formation amount have a positive correlation, the conventional techniques (1) and (2) work effectively. On the other hand, as for the film formation conditions of GaN, the temperature on the substrate (from 1000 ° C.) is much higher than the intermediate formation start temperature (about 450 ° C.) and the film formation start temperature (about 450 ° C.). For this reason, before the source gas reaches the substrate, it almost changes to the intermediate, making it difficult to control film formation uniformity.

  The object of the present invention is to suppress the amount of intermediates generated in the upstream part of the substrate and to make the intermediate concentration uniform on the substrate, so as not to cause a significant decrease in raw material utilization efficiency. An object of the present invention is to provide a semiconductor manufacturing apparatus capable of forming a film with high film thickness uniformity.

  In order to solve the above problems, in the present invention, a film forming method characterized in that the concentration on a substrate of a gas phase intermediate produced from a raw material gas by a chemical reaction is controlled, and a temperature control of a wall facing the substrate. A film forming apparatus that realizes this has been found.

  That is, the present invention is a method for forming a thin film on a substrate by introducing a raw material gas into a CVD (Chemical Vapor Deposition Chemical Vapor Deposition) apparatus, which comprises a gas phase intermediate produced from the raw material gas by a chemical reaction. The temperature on the substrate is cooled independently of the temperature of the substrate to keep the temperature on the upstream side of the source gas of the CVD apparatus lower than the generation temperature of the intermediate of the source gas. The present invention provides a film forming method for controlling the temperature of the opposing wall to increase sequentially from the side toward the downstream side.

Further, the present invention is a film forming apparatus for forming a thin film on a substrate by CVD using a source gas, a reaction chamber having a wall (hereinafter referred to as an opposing wall) facing a susceptor on which the substrate is placed,
A gas inlet for introducing the source gas into the reaction chamber;
A gas outlet for discharging the source gas from the reaction chamber;
Means for heating the substrate;
Cooling means installed on the back side of the opposing wall, and controlling the temperature of the opposing wall independently of the temperature of the substrate;
An intermediate concentration measuring means for measuring the concentration of the intermediate in the periphery of the substrate, crossed over the substrate of the reaction chamber or installed on a substantially vertical side wall;
A control mechanism for controlling the temperature on the upstream side of the source gas of the CVD apparatus to be lower than the generation temperature of the intermediate of the source gas and controlling the temperature of the opposing wall in order from the upstream side toward the downstream side. A film forming apparatus is provided.

  ADVANTAGE OF THE INVENTION According to this invention, in the method of forming thin films, such as a semiconductor thin film, by CVD, the film-forming method and film-forming apparatus which can form a uniform film in a substrate surface can be provided, As a result, the in-plane uniformity of a substrate can be provided. High thin film can be created.

  The present invention is applied to various source gases described in Patent Documents 1 to 5 and the like, and is particularly suitable for forming Ga-based thin films such as GaN, InGaN, AlGaN, and GaAs.

  One aspect of the present invention is a method of introducing a raw material gas into a CVD apparatus to form a thin film on a substrate, wherein a concentration of a gas phase intermediate produced from the raw material gas by a chemical reaction is controlled. A membrane method is provided. In another aspect of the present invention, a film forming apparatus that forms a thin film on a substrate by CVD using a source gas and has a wall (hereinafter referred to as an opposing wall) facing a susceptor on which the substrate is placed. A chamber, a gas inlet for introducing the source gas into the reaction chamber, a gas outlet for discharging the source gas from the reaction chamber, means for heating the substrate, and the reaction chamber on the opposing wall facing the reaction chamber And a cooling means for controlling the temperature of the opposing wall independently of the temperature of the substrate, and installed on a side wall that intersects or is substantially perpendicular to the substrate of the reaction chamber, A film forming apparatus having an intermediate concentration measuring means for measuring the concentration of a body is provided.

  The cooling is performed by a cooling means to control the concentration distribution on the substrate of the intermediate in the flow direction of the source gas. It is desirable to control the concentration distribution of the intermediate on the substrate so as to be uniform in the flow direction of the source gas.

  The facing wall temperature is sufficiently lower than the production temperature of the gas phase intermediate from the source gas inlet to the end position of the substrate closest to the source gas inlet (hereinafter referred to as the substrate upstream end), and the source gas It is preferable to control the edge position of the substrate closest to the discharge port (hereinafter referred to as the downstream end of the substrate) to be sufficiently higher than the generation temperature of the intermediate and to monotonously increase the temperature distribution to the downstream end of the substrate. Here, monotonous means linear or stepwise. The temperature sufficiently higher than the production temperature of the intermediate is a temperature at which the intermediate further reacts to form a film.

Ga (CH ₃ ) ₃ and NH ₃ are used as the source gas, and the intermediate in forming GaN as the thin film is GaNH ₂ (CH ₃ ) ₂ or a decomposition product thereof. This intermediate is further decomposed under heating to a thin film such as GaN.

  The temperature of the substrate is kept at 1000 to 1200 ° C., and the facing wall temperature is monotonically increased to 230 ° C. or less from the source gas introduction position to the substrate upstream end, to the substrate downstream end, and at the substrate downstream end. It is preferable to set to 520 ° C. or higher.

  It is desirable that a refrigerant is supplied to the cooling means, and the refrigerant is any one of water, silicone oil, alkyl alcohol, liquefied nitrogen, and combinations thereof.

  In still another aspect of the present invention, the opposing wall temperature is changed from the source gas inlet to the end position of the substrate closest to the source gas inlet (hereinafter referred to as the substrate upstream end). It is sufficiently lower than the generation temperature and is sufficiently higher than the generation temperature of the intermediate at the end position of the substrate closest to the source gas discharge port (hereinafter referred to as the substrate downstream end), and the temperature distribution to the substrate downstream end is linear. It is desirable to control so as to increase. The intermediate concentration measuring means is constituted by an infrared spectrophotometer, a mass spectrometer, or a combination thereof.

  The cooling means can control the concentration distribution on the substrate of the intermediate in the flow direction of the source gas. The concentration distribution on the substrate of the intermediate is controlled to be uniform in the flow direction of the source gas.

The present invention is also a film forming apparatus for forming a thin film on a substrate by CVD using a source gas, and a reaction chamber having a wall (hereinafter referred to as an opposing wall) facing a susceptor on which the substrate is placed;
A means for introducing the source gas into the reaction chamber; a means for discharging the source gas from the reaction chamber; a means for heating the substrate; and a back side of the opposing wall. There is provided a film forming apparatus having a cooling means for controlling based on a temperature at which the source gas generates an intermediate independently of a temperature of the substrate.

  The cooling means is arranged between the cooling means and a temperature control cell made of a heat conductor or a heat insulating material arranged adjacent to the opposing wall or via a gap and intersecting or perpendicularly dividing the gas flow direction. , A cooling means made of a heat conductor disposed adjacent to or through the cooling means, and a liquid cooling part provided in the cooling part.

  Further, the temperature control cell can be divided into a plurality in the direction from the facing wall toward the cooling means. Furthermore, it is preferable to control the opposing wall surface temperature by changing the material of the temperature control cell.

  The counter wall temperature is sufficiently lower than the generation temperature of the vapor phase intermediate from the source gas inlet to the end position of the substrate closest to the source gas inlet (hereinafter referred to as the substrate upstream end). Control is performed so that the temperature at the end position of the substrate closest to the source gas discharge port from the end (hereinafter referred to as the substrate downstream end) is sufficiently higher than the generation temperature of the intermediate and the temperature distribution to the substrate downstream end increases monotonously. It is desirable to do.

Ga (CH ₃ ) ₃ and NH ₃ are used as the source gas, and the intermediate in forming GaN as the thin film is GaNH ₂ (CH ₃ ) ₂ or a decomposition product thereof.

  The temperature of the substrate is kept at 1000 to 1200 ° C., and the facing wall temperature is monotonically increased from the source gas introduction position to the substrate upstream end to 230 ° C. or less, and from the substrate upstream end to the substrate downstream end, It is preferable to set the temperature at 520 ° C. or more at the downstream end of the substrate.

  Furthermore, the cooling means is individually provided in a cooling cell made of a heat conductor that is divided into a plurality of parts intersecting or substantially perpendicular to the flow direction of the source gas, a gap between the cooling cells, and the cooling cell. It can be comprised by the liquid cooling part provided.

  The opposing wall is not limited to being formed in an integral structure from upstream to downstream in the reaction chamber, but can be divided in accordance with the position of the gap between the cooling cells, and purge gas can flow through the gap into the reaction chamber. The facing surface temperature can be controlled by the flow rate or temperature of the refrigerant flowing in the liquid cooling section. The number of divisions of the cooling flow path at the position corresponding to the substrate is preferably 2 or more, particularly 3 or more, and preferably 6 or less, particularly 4 or less.

  It is preferable that temperature detecting means is provided in the facing wall, and the temperature control means is controlled in real time so that the facing wall temperature always becomes a specified temperature. The substrate, the susceptor, the opposing wall, the reaction chamber, the heating unit, and the cooling unit may be configured in an axisymmetric shape so that the substrate and the susceptor revolve. Further, the substrate can be configured to rotate.

  According to the present invention, there is provided a III-V group compound semiconductor device whose film thickness variation is ± 1% or less between the maximum thickness and the minimum thickness.

In still another aspect of the present invention, Ga (CH ₃ ) ₃ and NH ₃ are used as the source gas, and the intermediate when forming GaN as the semiconductor film is GaNH ₂ (CH ₃ ) ₂ or this It is a decomposition product, the temperature of the substrate is maintained at 1000 to 1200 ° C., the facing surface temperature is 220 ° C. or less from the introduction position of the source gas to the upstream end of the substrate, and from the upstream end of the substrate to the downstream end of the substrate The film forming method increases monotonically up to 520 ° C. at the downstream end of the substrate.

  Hereinafter, a film forming method and a film forming apparatus of the present invention will be described in detail with reference to the drawings, taking a semiconductor manufacturing apparatus as an example.

  FIG. 1 is a longitudinal sectional view showing a configuration of a semiconductor manufacturing apparatus according to a first embodiment, (a) is a longitudinal sectional view of a semiconductor manufacturing apparatus according to the first embodiment of the present invention, and (b) is (a). It is a figure which shows the cross-sectional view along the AA 'line of (). Further, (c) is a diagram showing a cross-sectional view along the line B-B 'in (a).

FIG. 2A shows the concentration distribution of the intermediate (GaNH ₂ (CH ₃ ) ₂ and its decomposition product) immediately above the substrate 101 in the conventional semiconductor manufacturing apparatus and the semiconductor manufacturing apparatus of the present invention, and FIG. (C) is a figure which shows the temperature distribution just under an opposing wall at this time. (D) is side surface sectional drawing which shows the area | region which has reached the intermediate body formation temperature in reaction chamber.

  The semiconductor manufacturing apparatus according to this embodiment has a carbon susceptor 102 on which a 2.5-inch substrate 101 is placed, and a quartz bottom wall 103 connected to the susceptor 102 inside, and a quartz facing surface facing the susceptor 102. A reaction chamber 105 having a wall 104 is provided. The reaction chamber 105 includes a gas inlet 106 for supplying a source gas and a carrier gas, and a gas outlet 107 for discharging the source gas and the carrier gas from the reaction chamber 105 to the outside of the system. . In addition, a heater 108 for heating the substrate 101 is provided outside the susceptor 102, and a stainless steel cooling jacket 109 is provided outside the opposing wall 104. Further, the semiconductor manufacturing apparatus of the present embodiment has a quartz infrared incident window 110 on one side of the reaction chamber side wall and a quartz infrared detection window 111 on the side wall of the reaction chamber facing this, and the red is outside the system. It has an outer spectrophotometer 114.

  FIG. 1B is a cross-sectional plan view showing a cross section taken along the line A-A ′ in FIG. Thus, the cooling jacket 109 has five flow paths I to V, and the cooling liquid (refrigerant) crosses the gas flow or flows in the vertical direction 112. FIG.1 (c) is a figure which shows the cross section along the B-B 'line | wire in Fig.1 (a). As described above, the infrared incident window 110 and the infrared detection window 111 are formed on the substrate 101 so that the infrared path 113 incident into the reaction chamber intersects or is almost perpendicular to the gas flow direction and passes directly above the substrate 101. Three places will be provided at corresponding positions. The infrared spectrophotometer 114 is connected to the computer 115 and measures the frequency unique to each intermolecular bond.

In the semiconductor manufacturing apparatus configured as described above, the substrate surface temperature is set constant at 1000 ° C. by the heater 108. As a source gas, ammonia (NH ₃ ) is used as a group V source gas, trimethylgallium (TMG) gas is used as a group III source gas, and hydrogen gas (H ₂ ) is used as a carrier gas. The source gas introduced from the gas inlet 106 is heated as it approaches the susceptor 102 to generate various intermediates, and a part thereof forms a gallium nitride (GaN) film on the substrate.

Here, according to the inventor's own study, GaNH ₂ (CH ₃ ) ₂ or GaNH ₂ (CH ₃ ) whose generation start temperature is almost equal to the film formation start temperature (450 ° C.) of GaN among various intermediates. It was revealed that the decomposition product from ₂ is the intermediate that contributes most to the film formation of GaN. Therefore, an infrared spectrophotometer 114 is used to inject infrared light into the reaction chamber 105 from the infrared incident window 110 and detect the infrared light passing through the infrared detection window 111 to detect GaNH ₂ (CH ₃ ) ₂ and this decomposition product. Measure the concentration. At this time, the stretching mode of Ga-N is measured. Further, since the measurement is made through a quartz window, the amount of infrared absorption by quartz must be taken into consideration. The flow rate and temperature of the coolant are adjusted so that the GaNH ₂ (CH ₃ ) ₂ concentration on the substrate 101 measured in this way is uniform.

2 (a) to 2 (d) show the GaNH ₂ (CH ₃ ) ₂ concentration distribution just above the substrate and the GaN on the substrate in the conventional semiconductor manufacturing apparatus and the semiconductor manufacturing apparatus of the present invention shown in FIG. 1 (a). It is a figure which shows film-forming speed distribution and the temperature distribution just under an opposing wall. In the following description, the substrate position closest to the gas inlet 106 is defined as the substrate upstream end, and the substrate position closest to the gas outlet 107 is defined as the substrate downstream end. In the conventional semiconductor manufacturing apparatus, a large amount of GaNH ₂ (CH ₃ ) ₂ is generated before the substrate 101 and rapidly decreases from the substrate upstream end to the substrate downstream end. On the other hand, the concentration distribution of GaNH ₂ (CH ₃ ) ₂ and its decomposition products in the semiconductor manufacturing apparatus in this example is almost uniform on the substrate. The GaN deposition rate distribution on the substrate also substantially corresponds to the concentration distribution of GaNH ₂ (CH ₃ ) ₂ and its decomposition products.

  This cause can be explained from the relationship between the temperature distribution in the reaction chamber and the intermediate generation region. FIG. 2D is a diagram showing a temperature region in which an intermediate can be generated in the reaction chamber. In the conventional semiconductor manufacturing apparatus, the temperature of the opposing wall surface has already reached the intermediate formation temperature at the substrate upstream end. For this reason, most of the introduced source gas is converted into an intermediate before reaching the upstream end of the substrate. Since these intermediates reach the substrate 101 and are rapidly formed and consumed at the same time, the material is depleted at the downstream end of the substrate.

  In contrast, in the semiconductor manufacturing apparatus of this example, the opposing wall temperature from the gas inlet 106 to the upstream end of the substrate is set sufficiently lower than the intermediate generation start temperature (450 ° C.). The intermediate generation possible region is limited to the vicinity of the substrate 101. Furthermore, the opposing wall temperature from the upstream end of the substrate to the downstream end of the substrate gradually increases, and spreads to the opposing wall surface in a crossing direction or a substantially vertical direction. Thereby, the amount of intermediates generated at the upstream end of the substrate is suppressed, and the material depletion at the downstream end of the substrate can be prevented.

  Furthermore, the intermediate formed on the opposite wall side diffuses so as to cancel the decrease in the intermediate concentration in the vicinity of the substrate caused by the film formation, so that the GaN film formation rate on the substrate is made uniform. That is, the temperature of the facing wall facing the substrate is kept lower than the temperature at which the intermediate is formed upstream of the reaction gas, and gradually rises when it reaches the region of the substrate and rises to the temperature required for film formation. . That is, in the present invention, the temperature of the opposing surface of the substrate is not uniform and rises from upstream to downstream. This may be linear or may be stepwise or non-linear to some extent as long as it does not hinder uniform film formation. However, increasing substantially linearly is most preferable in forming a thin film having a uniform film thickness and a uniform composition.

In addition to the infrared spectrophotometer 114, a mass spectrometer may be used for measuring the concentration of the intermediate. When using a mass spectrometer, an extraction port for extracting gas in the reaction chamber is provided on the side wall of the reaction chamber 105 in place of the light incident / detection port, and GaNH ₂ (CH ₃ ) ₂ having a mass number of 116 and its decomposition are provided. The product needs to be measured.

  According to the above embodiment, a very uniform III-V compound semiconductor device was able to be manufactured with a variation in film thickness of ± 1% or less between the maximum thickness and the minimum thickness. Such a uniform semiconductor device could be manufactured in the same manner in other examples.

  FIG. 3 is a longitudinal sectional view showing the configuration of the semiconductor manufacturing apparatus according to the second embodiment, (a) is a longitudinal sectional view of the semiconductor manufacturing apparatus according to the second embodiment of the present invention, and (b) is a diagram C of (a). It is a figure which shows the cross-sectional view along line -C '.

  FIG. 4A is a graph showing the temperature distribution of the substrate and the opposite wall surface calculated in the conventional semiconductor manufacturing apparatus and the semiconductor manufacturing apparatus of the present invention, and FIG. 4B is the GaN film formation rate distribution at this time. It is a graph which shows.

  FIG. 5 is a view showing another method of dividing the coolant flow path of FIG. FIG. 6 is a view showing another configuration from the cooling jacket 109 to the opposing wall surface.

  The semiconductor manufacturing apparatus according to this embodiment has a carbon susceptor 102 on which a 2.5-inch substrate 101 is placed, and a quartz bottom wall 103 connected to the susceptor 102 via a heat insulating material, and faces the susceptor 102. A reaction chamber 105 having an opposing wall 104 made of quartz is provided, a gas inlet 106 for supplying a source gas and a carrier gas into the reaction chamber, and a gas outlet 107 for discharging the source gas and the carrier gas from the reaction chamber 105 to the outside of the system. Have In addition, a heater 108 for heating the substrate 101 is provided outside the susceptor 102, and a stainless steel cooling jacket 109 is provided outside the opposing wall 104.

  FIG. 3B is a view showing a cross section taken along line C-C ′ of FIG. As described above, the cooling jacket 109 includes five flow paths I to V, and the cooling liquid crosses the gas flow or flows in a substantially vertical direction.

In the semiconductor manufacturing apparatus configured as described above, the substrate surface temperature is set constant at 1000 ° C. by the heater 108. On the other hand, with respect to three independent flow paths of the cooling jacket 109, cooling water whose flow rate or temperature is adjusted independently is supplied to set the opposing wall temperature. At this time, it is necessary to grasp the relationship between the flow rate or temperature of the coolant and the opposing wall temperature in advance by experiment or simulation. As the source gas, ammonia (NH ₃ ) is used as the group V source gas, trimethylgallium (TMG) gas is used as the group III source gas, and hydrogen gas is used as the carrier gas. The source gas introduced from the gas inlet 106 is heated as it approaches the substrate 101 to generate various intermediates, and gallium nitride (GaN) is formed on the substrate.

The opposing wall surface temperature during film formation needs to be determined in consideration of the temperature at which an intermediate is generated from TMG and NH ₃ and the reduction of the intermediate due to film formation. There are many types of intermediates produced from raw material gases by chemical reaction. According to the inventor's original study, it has been clarified that GaNH ₂ (CH ₃ ) ₂ and its decomposition products are the most intermediates contributing to the film formation of GaN. The generation start temperature of GaNH ₂ (CH ₃ ) ₂ is substantially equal to the film formation start temperature (about 450 ° C.). Therefore, the opposing wall surface temperature is kept sufficiently low from the gas inlet 106 to the upstream end of the substrate to 230 ° C. or less, and increases monotonically and in a stepwise daily linear manner from the upstream end of the substrate to the downstream end of the substrate, and reaches 520 Set so that it is above ℃.

  4A shows the temperature distribution of the opposing wall surface simulated in the conventional semiconductor manufacturing apparatus and the semiconductor manufacturing apparatus of the present invention shown in FIG. 3A, and FIG. 4B shows the GaN film formation rate on the substrate. It is a graph which shows distribution. In the conventional semiconductor manufacturing apparatus, the temperature of the opposing wall surface has already reached the intermediate formation temperature at the substrate upstream end. For this reason, most of the introduced source gas is converted into an intermediate before reaching the upstream end of the substrate. Since these intermediates reach the substrate 101 and are rapidly formed and consumed at the same time, the material is depleted at the downstream end of the substrate.

  In contrast, in the semiconductor manufacturing apparatus of this embodiment, the opposing wall temperature from the gas inlet to the upstream end of the substrate is set sufficiently lower than the intermediate generation temperature, and the intermediate generation possible region at the upstream end of the substrate is defined as the substrate 101. It is limited to the vicinity. Furthermore, the temperature of the opposing wall gradually increases from the upstream end of the substrate to the downstream end of the substrate, so that the intermediate productable region crosses or extends vertically to the opposing wall surface. Thereby, the amount of intermediates generated at the upstream end of the substrate is suppressed, and the material depletion at the downstream end of the substrate is suppressed. Furthermore, the intermediate formed on the opposite wall side diffuses so as to cancel the decrease in the intermediate concentration in the vicinity of the substrate caused by the film formation, so that the GaN film formation rate on the substrate is made uniform.

  FIG. 5 is a diagram showing another example of dividing the flow path of the cooling jacket 109. The division position of the flow path is not limited to the division shown in FIG. 3A as long as the opposing wall surface temperature distribution as shown in FIG. In FIG. 5, the number of divisions of the flow path is increased. In particular, by increasing the number of divisions from the upstream end of the substrate where the temperature change of the opposing wall 104 is large to the downstream end of the substrate, the opposing wall temperature can be controlled with higher accuracy. This is particularly effective when expanding the substrate area.

  FIG. 6 shows another example of the configuration from the cooling jacket 109 to the opposing wall surface. It is necessary to use the facing wall material 201 that is stable at least in the operating temperature range (normal temperature to 1000 ° C.) of the apparatus and has a small degassing amount. Further, it is desirable that the surface emissivity of the opposing wall surface is low. In addition, it is desirable that the heat transfer coefficient be as high as possible from the cooling jacket 109 to the opposing wall surface. As shown in FIG. 6, the opposing wall 104 may be composed of a plurality of plates made of different materials. For example, quartz having a small degassing amount may be used for the opposing wall surface material 201, and carbon having high thermal conductivity may be used for the opposing wall inner member 202. Further, the facing wall 104 and the cooling jacket 109 do not need to be in contact with each other, and the space 203 may be provided. When the space 203 is provided, the heat transfer rate from the cooling jacket 109 to the opposing wall 104 is deteriorated, but the opposing wall 104 can be prevented from being destroyed when the opposing wall 104 is deformed by thermal stress.

  The water-cooled jacket is preferably made of a material having high thermal conductivity, and aluminum, copper, etc. may be used in addition to stainless steel. In addition to water, silicone oil, alkyl alcohol, liquefied nitrogen, or a combination thereof may be used as a coolant flowing in the cooling jacket 109.

  FIG. 7 is a longitudinal sectional view showing a semiconductor manufacturing apparatus according to Embodiment 3 of the present invention. Elements similar to those in FIG. 1A are denoted by the same reference numerals. The main configuration of the apparatus is the same as that of the semiconductor manufacturing apparatus according to the second embodiment shown in FIG. 3A, except that a plurality of cooling means 109 are arranged in the flow direction and a gap 301 between the cooling jackets. It is comprised by. In this way, the controllability of the facing wall temperature can be improved.

  When the cooling means is constituted by the integral cooling jacket 109, heat conduction occurs through the stainless steel between the flow paths, the temperatures of the respective cooling liquids affect each other, and the temperature gradient between the flow paths is smoothed. The temperature distribution of the opposing wall surface is further smoothed during the heat conduction process in the opposing wall. Each flow path is made up of individual cooling jackets 109, and by reducing the heat transfer coefficient between them, the heat insulation between the cooling jackets can be maintained, and the difference in the cooling amount of each cooling jacket can be clarified. This can be reflected on the facing wall 104. This embodiment is particularly effective when the opposing wall 104 is thick. Instead of providing the gaps 301 between the jackets, a heat insulating material such as boron nitride (BN) may be used.

FIG. 8 is a longitudinal sectional view showing a semiconductor manufacturing apparatus according to Embodiment 4 of the present invention. Elements similar to those in FIG. 1A are denoted by the same reference numerals. The main configuration of the apparatus is the same as that of the semiconductor manufacturing apparatus according to the second embodiment shown in FIG. 2, but the opposing wall 104 is divided in accordance with the position of the gap between the cooling jackets, and nitrogen gas is introduced into the reaction chamber through the gap 301. A purge gas 401 such as (N ₂ ) or H ₂ is flowed. In this way, the size of the semiconductor device can be increased. As shown in FIG. 3A, when the opposing wall 104 is constituted by a single plate and is increased in size, destruction due to thermal stress is likely to occur. Breaking can be suppressed by dividing the opposing wall 104 into a configuration. Further, in order to prevent the source gas from entering the gap 301, the purge gas 401 is introduced at a flow rate that does not affect the gas flow in the reaction chamber.

  FIG. 9 is a longitudinal sectional view showing a semiconductor manufacturing apparatus according to Embodiment 5 of the present invention. Elements similar to those in FIG. 1A are denoted by the same reference numerals. The main configuration of the apparatus is the same as that of the semiconductor manufacturing apparatus according to the second embodiment shown in FIG. 3A, but a thermocouple 501 and a thermocouple 501 are connected by a signal line 502 to measure the temperature distribution in the opposing wall. A computer 405 for PID temperature control that compares and calculates a measured value and a preset value of the opposing wall surface temperature, a mass flow controller 406 that adjusts the flow rate and temperature based on the output from the computer, and a temperature controller 407. The pump 408 that controls the flow rate of the refrigerant is controlled by commands of the mass flow controller 406 and the temperature controller 407. A specific method of control is as shown in the flowchart of FIG.

  Hereinafter, description will be made based on the flowchart of FIG. First, the specified value of the opposing wall temperature distribution is determined by prior examination. This designated value is input to the computer, and compared with the measured value of the thermocouple 501 installed in the opposite wall, the control amount of the coolant flow rate and temperature is calculated. Adjust the output of the mass flow controller and temperature controller based on the controlled variable. If the thermocouple temperature matches the specified value, the output of the mass flow controller / temperature controller is held. If not, the control amount is calculated again by the computer. In this way, the opposing wall temperature during film formation can be kept constant at all times, and more accurate film thickness control becomes possible.

  During the growth of GaN, film formation occurs on the wall surface other than the substrate. In particular, the opposing wall surface is at a relatively low temperature, and the attached film is not transparent but yellow to black. For this reason, the surface emissivity of the opposing wall surface varies greatly with the film formation time. When the cooling amount of the opposing wall 104 is constant, the opposing wall temperature also changes with the change in the surface radiation rate of the opposing wall surface, and the targeted film thickness distribution cannot be obtained. As in this embodiment, the opposing wall temperature at the time of GaN growth is detected in real time and fed back to the temperature or flow rate of the cooling liquid, so that the opposing wall temperature can be prevented from changing with time and can always be maintained at a constant temperature.

  FIG. 11 shows a semiconductor manufacturing apparatus according to Embodiment 6 of the present invention, and FIG. 11 (a) is a side sectional view. FIG.11 (b) is a cross-sectional view along the D-D 'line | wire of Fig.11 (a). Elements similar to those in FIG. 1A are denoted by the same reference numerals. In this example, the gas inlet 106 of the semiconductor manufacturing apparatus described in Examples 2 to 5 is rotated about one axis, and the substrate 101 is rotated and revolved around the axis 602. It is intended for a so-called self-revolving semiconductor manufacturing apparatus that processes the substrate 101 simultaneously.

  The flow path of the cooling jacket 109 is formed in a ring shape centering on the revolution shaft 602. In this way, even in the self-revolving semiconductor manufacturing apparatus, the opposing wall surface temperature can be controlled, the amount of intermediate generation at the upstream end of the substrate can be suppressed, and the material depletion at the downstream end of the substrate can be prevented, Furthermore, the intermediate produced on the opposite wall side diffuses so as to cancel the decrease in the intermediate concentration on the substrate, and the GaN film formation rate on the substrate can be made uniform.

  FIG. 12 is a sectional view of a semiconductor manufacturing apparatus according to Embodiment 6 of the present invention. Elements similar to those in FIGS. 1A and 7 are denoted by the same reference numerals. The main configuration of the apparatus according to the present embodiment is the same as that of the semiconductor device according to the first embodiment shown in FIG. 1A, but the cooling means includes a plurality of temperature control cells 121 and a cooling jacket 109. By changing the material of the temperature control cell 121 for each cell, the thermal conductivity between the cooling jacket 109 and the opposing wall surface is changed to adjust the temperature of the opposing wall surface.

  Between the temperature control cells, a gap is provided particularly in the gas flow direction. Thereby, the heat insulation between cells improves, the difference in the cooling amount for every cell can be more clearly reflected on an opposing wall, and an opposing wall surface temperature can be controlled correctly. Further, since it is not necessary to divide the liquid cooling flow path, the apparatus structure can be simplified.

The structure of the film-forming apparatus by the Example of this invention is shown, (a) is sectional side view, (b) is AA 'sectional drawing of (a), (c) is BB' line of (a). FIG. The relationship between the position of the opposing wall surface of the substrate and the reaction vessel in the present invention and the conventional example is shown, (a) is the intermediate concentration on the substrate, (b) is the GaN film formation rate, and (c) is the substrate facing surface temperature. , (D) is the temperature distribution in the reaction vessel. The structure of the film-forming apparatus by the other Example in this invention is shown, (a) is side surface sectional drawing, (b) is a cross-sectional view with respect to the C-C 'line | wire of (a). The characteristic relationship of the board | substrate of the conventional semiconductor manufacturing apparatus and the semiconductor manufacturing apparatus of this invention and an opposing wall surface is shown, (a) is the temperature distribution of the board | substrate right above and the opposing wall surface calculated | required by calculation, (b) is GaN at this time The film deposition rate distribution. Side surface sectional drawing which shows the other division method of the cooling fluid flow path of Fig.3 (a). Side surface sectional drawing which showed another structure from a cooling jacket to an opposing wall surface. The side sectional view of the semiconductor manufacturing device by other examples of the present invention. FIG. 6 is a side sectional view of a semiconductor manufacturing apparatus according to another embodiment of the present invention. 1 is a schematic configuration diagram of a semiconductor manufacturing apparatus system according to an embodiment of the present invention. The flowchart of the temperature control in the Example of this invention. FIG. 6 is a cross-sectional view of a semiconductor manufacturing apparatus according to still another embodiment of the present invention, in which (a) is a side cross-sectional view and (b) is a cross-sectional view taken along line D-D ′ of (a). Sectional drawing of the semiconductor manufacturing apparatus by Example 6 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Board | substrate, 102 ... Susceptor, 103 ... Bottom wall, 104 ... Opposite wall, 105 ... Reaction chamber, 106 ... Gas inlet, 107 ... Gas outlet, 108 ... Heater, 109 ... Cooling jacket, 110 ... Infrared incident window, DESCRIPTION OF SYMBOLS 111 ... Infrared detection window, 112 ... Coolant flow direction, 113 ... Infrared traveling direction, 114 ... Infrared spectrophotometer, 115 ... Computer, IV ... Coolant flow path, 201 ... Opposite wall material, 202 ... Opposite wall Inner member, 203 ... space, 301 ... gap, 401 ... purge gas, 501 ... thermocouple, 601 ... rotation axis, 602 ... revolution axis, 603 ... gas inlet, 604 ... coolant flow direction.

Claims (9)

A method of forming a thin film on a substrate by installing a substrate on which a thin film is to be formed, introducing a source gas into a CVD (Chemical Vapor Deposition) apparatus having a reaction chamber having an opposing wall facing the substrate. The concentration of the vapor phase intermediate produced from the source gas by a chemical reaction on the substrate is cooled independently from the temperature of the substrate from the upstream side to the downstream side of the source gas of the CVD apparatus. A method of forming a film , wherein the temperature of the facing wall is controlled so as to be sequentially increased, and the temperature of the facing wall upstream of the source gas is kept lower than the generation temperature of the gas phase intermediate , The temperature of the facing wall is sufficiently lower than the production temperature of the gas phase intermediate from the source gas inlet to the substrate upstream end defined by the end position of the substrate closest to the source gas inlet, From the upstream end of the plate to the downstream end of the substrate defined at the end position of the substrate closest to the source gas discharge port is sufficiently higher than the generation temperature of the vapor phase intermediate, from the upstream end of the substrate to the downstream end of the substrate. The film forming method is characterized in that the temperature distribution is controlled so as to increase monotonously . The film forming method according to claim 1 , wherein the cooling is performed by a cooling unit that cools the facing wall, and the concentration distribution on the substrate of the intermediate in the flow direction of the source gas is controlled. The film forming method according to claim 2, wherein the concentration distribution on the substrate of the intermediate, and controls so as to uniform one flow direction of the raw material gas. Ga (CH ₃ ) ₃ and NH ₃ are used as the source gas, and the intermediate in forming GaN as the thin film is GaNH ₂ (CH ₃ ) ₂ or a decomposition product thereof. The film forming method according to claim 1. The temperature of the substrate is kept at 1000 to 1200 ° C., and the temperature of the opposing wall surface is monotonically increased from the source gas introduction position to the substrate upstream end to 230 ° C. or less, and from the substrate upstream end to the substrate downstream end. the film forming method according to claim 1, characterized in that set to 520 ° C. or higher in the substrate downstream end. The coolant supplied to the cooling means, the refrigerant, water, film forming method according to claim 2, wherein the silicone oil is an alkyl alcohol, one of liquid nitrogen and their combinations. A film forming apparatus for forming a thin film on a substrate through a gas phase intermediate generated by a chemical reaction by CVD using a source gas,
A reaction chamber having an opposing wall facing the susceptor on which the substrate is placed;
A gas inlet for introducing the source gas into the reaction chamber;
A gas outlet for discharging the source gas from the reaction chamber;
Heating means for heating the substrate;
Cooling means that is installed on the opposite wall opposite to the substrate and controls the temperature of the opposite wall independently of the temperature of the substrate;
The temperature of the opposing wall is sufficiently lower than the production temperature of the gas phase intermediate from the source gas inlet to the substrate upstream end defined at the end position of the substrate closest to the source gas inlet, From the substrate upstream end to the substrate downstream end defined at the end position of the substrate closest to the source gas discharge port is sufficiently higher than the generation temperature of the intermediate, and from the substrate upstream end to the substrate downstream end. A film forming apparatus comprising a control mechanism for controlling the temperature distribution so as to increase monotonously. The film forming apparatus according to claim 7, wherein the cooling unit is installed on a side wall of the reaction chamber that intersects or is perpendicular to the substrate. The film forming apparatus according to claim 7, further comprising intermediate concentration measuring means for measuring the concentration of the intermediate in the periphery of the substrate.

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