JPH11236675A - Thin film forming device and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the device capable of forming a thin film with uniform thickness at high operating ratio by providing a heating mechanism with a resistance heating mechanism and a high frequency heating mechanism, thereby partially heating only the substrate to be deposited such as a silicon substrate. SOLUTION: As a heating means, a resistance heating heater 150 and a high frequency heater 160 are provided. The whole body of the inside of a reaction vessel 141 is heated by the resistance heating heater 150, and simultaneously, only the material which can be heated by high frequency induction is selectively heated as well by using the high frequency heater 160, and a high temp. can partially be obtained. In this way, e.g. in the case the material to be heated is subjected to high frequency induction such as a silicon substrate, only the part can be made a temp. higher than the vicinity thereof. There is no limitation in the positional relation between the resistance heating heater 150 and the high frequency heater 160, and the resistance heating heater 150 may be arranged on the inside or outside of the high frequency heater 160, or they may be arranged alternately on the same circumference of a circle. The sticking of deposits to the side wall of the reaction vessel 141 or the like and stuck materials onto the substrate caused by the peeling thereof are reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film forming apparatus and a thin film forming method, and more particularly to a thin film forming apparatus and a thin film forming method for forming a capacitor insulating thin film using a high dielectric constant material and a ferroelectric material as an insulating film. It is about the method.

[0002]

2. Description of the Related Art Semiconductor integrated circuits typified by dynamic random access memory (hereinafter abbreviated as DRAM) have been used in recent years as their applications have been diversified and the equipment used has become more sophisticated. Higher integration and ultra-miniaturization are in progress. Along with this, design rules used in device manufacturing have been required to rapidly reduce their minimum dimensions. However, for example, DR
In a capacitor used for an AM cell, it is required for the purpose to maintain the capacitor capacity at a certain value or more. For this reason, by making the element structure of the semiconductor element three-dimensional, more effective area is secured in the same unit area,
Also, for example, the capacitor insulating film is made extremely thin, or
There is an increasing demand for using a high dielectric thin film as a capacitor insulating film to secure more capacitor capacity with the same effective area.

[0003] Under such circumstances, as a film forming technique, chemical vapor deposition (hereinafter referred to as CVD).
Abbreviated. ) The importance of the law is increasing. That is, in general, the CVD method is excellent in precision control of composition and reproducibility of a process, and has an advantage that excellent step coverage can be obtained by forming a film under a reaction rate-determining condition. Because of these features, CVD
The method is advantageous in that, when an element is formed three-dimensionally, an insulating film, an electrode, and the like are formed thin and with good uniformity, and good reliability is secured. Among them, ensuring excellent step coverage is particularly important for high integration and ultra-miniaturization, and cannot be realized by other film forming techniques such as sputtering.
This is a major motivation to adopt the VD method.

[0004] In the CVD method, it is essential to form a film under a reaction rate-determining condition in order to ensure good step coverage. It is also known that when a film is formed under a reaction-determining condition, the film forming speed and film characteristics strongly depend on the film forming temperature.
For this reason, a hot-wall type CVD apparatus which can obtain a uniform temperature distribution relatively easily is most suitable for such purpose. Hot wall type CVD equipment is also excellent in terms of mass productivity and maintenance / management of equipment, and hot wall type CVD equipment is now the mainstream as a film forming equipment.

[0005] On the other hand, there is a movement to promote high integration and ultra-miniaturization of semiconductor integrated circuits by using new materials having excellent functions which have never been seen before. For example, in the case of DRAM, the use of a high dielectric constant material having a higher dielectric constant than a conventional silicon oxide / silicon nitride laminated film has been studied as a capacitor insulating film material so that sufficient capacitor capacity can be secured even if the capacitor area is reduced. I have. Strontium titanate (SrTiO ₃ ; hereinafter abbreviated as STO) strontium barium titanate (Ba _x Sr _1-x T
iO ₃ (0 <x <1; hereinafter abbreviated as BST) and the like. The ferroelectric lead zirconate titanate showing the _{(PbZr x Ti 1-x O} 3 (0 <x <1; hereinafter PZT abbreviated) and strontium bismuth tantalum oxide (S
Development of functional material thin films such as rBi ₂ Ta ₂ O ₉ (hereinafter abbreviated as SBT) is also progressing, and FeRAM (Ferroelec) is being developed.
Devices with completely new functions such as tronic random access read / write memory) have been proposed. It is desirable to use a hot wall type CVD apparatus from the above-mentioned point also as a technique for forming a film of these new materials.

A conventional hot wall type CVD apparatus (thin film forming apparatus) used for forming a high dielectric constant material thin film will be described below.
And the CVD method (thin film forming method). FIG. 4 is a sectional view of a main part of a conventional hot wall type CVD apparatus.

In FIG. 4, reference numeral 141 denotes a quartz bell jar type reaction vessel whose lower part is open, and a stainless steel manifold 142 is connected via an O-ring 143 to its lower part. An inner tube 144 made of quartz is mounted on the manifold 142 inside the reaction vessel 141 almost in parallel with the side wall of the reaction vessel 141 in order to rectify gas and improve heat uniformity. The lower portion of the manifold 142 is connected via an O-ring 145 to a stainless steel cap 146 so as to cover the reaction vessel 141 from below.
1. Manifold 142, stainless steel cap 146
This keeps the inside of the reaction vessel 141 airtight. A vertical drive mechanism 170 is connected to a lower portion of the stainless steel cap 146, whereby the stainless steel cap 146 is supported and can be moved up and down.

At the center of the stainless steel cap 146, a stainless steel cap 146 is placed via a sealing material (not shown).
A rotating mechanism 147 that penetrates the inside of the inner tube 144 is provided inside the reaction vessel 141 above the rotating mechanism 147. A plurality of silicon substrates can be placed on the substrate boat 149 in parallel and at equal intervals.

The carrier gas supply pipes 1221 and 1231, the raw material gas supply pipe 1 are provided on one side of the manifold 142.
131 are connected to each other, an exhaust port 153 is connected to the other side surface, and a tip of the exhaust port 153 is connected to a pressure regulator 155.
Is connected to the exhaust pump 154 via the. The mass flow controller 122,
Gas (Ar, oxygen) whose flow rate is controlled via 123
Is supplied.

One end of the source gas supply pipe 1131 is connected to gas nozzles 151 and 152 inside the manifold. The gas nozzles 151 and 152 supply the source gas between the inner tube 144 made of quartz and the substrate boat 149 and to the substrate boat 149 side. They are separated and fixed from each other so that they can be ejected.

A pipe is provided at the other end of the source gas supply pipe 1131.
Organometallic liquid raw material containers 101, 102 via valves
103 is connected, and an organic metal gas as a raw material for forming a thin film can be supplied. The organic metal materials supplied from these organic metal liquid material containers are mixed in a liquid material mixing manifold 111, weighed by a liquid material weighing micropump 112, and vaporized by a liquid material vaporizer 113. An Ar carrier gas having a controlled flow rate is introduced into the liquid source vaporizer 113 via a pipe (not shown), and the vaporized organometallic material is transported by the Ar carrier gas and passes through a source gas supply pipe 1131. Then, it is introduced into the reaction vessel 141. Also, the raw material gas supply pipe 11
Numeral 31 is placed in a thermostat (not shown) or a ribbon heater (not shown) is wound thereon to prevent liquefaction of the organic metal in the tube.

On the other hand, a resistance heater 150 made of Super Kanthal
However, the power supply unit (not shown) can be electrically heated by a power supply unit so that the entire substrate boat 149 can be maintained at a uniform temperature. Next, a method of forming an insulating film using the above-described conventional thin film forming apparatus will be described. First, twelve 8-inch silicon substrates were mounted on the respective substrate mounting portions of the substrate boat 149. As a silicon substrate, the surface is thermally oxidized and 5
The one on which a Ru film of 0 nm was formed was used. Thereafter, the inside of the reaction vessel was replaced with gas, and Ar was used as a carrier gas for 100 hours.
The internal pressure of the reaction vessel 141 was controlled at 0.5 Torr by flowing 500 sccm of oxygen and oxygen (O ₂ ), and the silicon substrate was heated by the resistance heater 150 to 420 ° C.

After the internal pressure and temperature are stabilized, the desired composition ratio (Ba: Sr = 1: 1, (Ba + Sr): Ti = 1: 1)
Ba, whose mixing ratio is controlled so that the thin film of 1) is formed,
Sr and Ti organometallic raw material gases are supplied to the raw material gas supply pipe 1
The gas was supplied from 131 to the reaction vessel 141 via gas nozzles 151 and 152.

This state was maintained for 30 minutes to form a BST film. Thereafter, the supply of the organometallic raw material gas was stopped to terminate the film formation, and the silicon substrate was further heated by the resistance heater 150 while Ar and O ₂ were flowing, and the temperature was raised to 650 ° C. After maintaining this state for 20 minutes to crystallize BST, the reaction vessel was cooled and the silicon substrate was taken out.

According to the above-described method, 20
A BST film having a desired composition was obtained with a thickness of nm. However, the above-described hot wall type CVD apparatus and CVD method have the following problems.

That is, since the temperature of the silicon substrate is controlled by heating from the outside of the CVD reaction vessel 141 by the resistance heater 150, the side wall, the substrate boat 149, and the gas nozzles 151 and 152 in the reaction vessel 141 are basically formed. Was maintained at the same temperature as the silicon substrate, and only the substrate could not be heated to a high temperature. Further, since the deposition rate of the BST film generally increases in proportion to the temperature, the reaction vessel 141 located on the upstream side of the silicon substrate on the supply of the raw material.
At the gas contacting surfaces such as the side wall, the substrate boat 149, and the gas nozzles 151 and 152, at least the same film deposition occurs as on the silicon substrate, and the deposits are separated and adhere to the silicon substrate, and the deposited film on the substrate is removed. There is an inconvenience that thousands or more defects occur. Further, as a result of such deposition, it was found that the raw material gas concentration decreased toward the downstream side, and it was not possible to maintain the reaction rate-determining condition soon. As a result, on the downstream side, not only the deposition amount of the film is remarkably reduced, the composition and the thickness of the deposited film are changed, but also non-uniformity occurs, and good step coverage cannot be maintained. Was. In particular, when a large-diameter silicon substrate such as 8 inches is used, there is a case where no film growth occurs at the downstream side.

In a hot-wall type CVD apparatus,
Originally, the utilization efficiency of the source gas is not high, and a large amount of the source gas must be supplied into the CVD reaction vessel 141. On the other hand, organometallic compounds have been used as CVD raw materials for metal oxides such as the above BST, but these compounds have a low vapor pressure and are thermally unstable, so there is a limit to the amount that can be supplied. . That is, even if a considerable amount of the raw material vapor is consumed, it is difficult to feed a sufficient amount of raw material vapor so that the reaction rate-determining condition can be maintained. Therefore, in order to maintain uniformity of the film thickness and composition between the silicon substrates and within the same silicon substrate, and to ensure good step coverage on all the silicon substrates, the inner wall of the reaction vessel 141, the substrate boat 149, the gas nozzle 151, It is indispensable to suppress the consumption of the source gas on the gas contact surface such as 152. However, in the above-described conventional CVD apparatus, this means that the temperature of the reaction tube itself is lowered, and this results in a sharp decrease in the deposition rate. That is, there has been a problem that the reaction rate-determining conditions cannot be maintained while securing the necessary deposition rate.

Furthermore, since the deposits on the inner wall of the reaction vessel 141 cause dust, the more the amount of deposits, the more frequent cleaning becomes necessary. However, these metal compounds and their constituent metals as attachments do not originally have compounds having a high vapor pressure, and it is extremely difficult to remove them with a cleaning gas. For this reason, washing with an acid such as hydrochloric acid or nitric acid is the simplest and most reliable method.However, in the case of acid washing, it takes a lot of time and effort to wash and dry, and during that time, the operation as a thin film forming apparatus is required. There was a problem of stopping.

Therefore, in order to increase the operation rate of the CVD apparatus and enable mass production, it is essential to suppress decomposition and adhesion of the raw material to the inner wall of the reaction vessel 142 as much as possible. By the way, as described above, it is indispensable for the CVD apparatus of these metal oxides to suppress the decomposition and adhesion of the raw material in parts other than the silicon substrate as much as possible. For this purpose, it is necessary to lower the temperature of the parts other than the silicon substrate to the raw material decomposition temperature or lower.

On the other hand, there is a method of complicating the structure of the substrate boat 149, the gas nozzles 151, 152, and so on, for example, by forming a double pipe, flowing a refrigerant inside and cooling the inside, but the cooling effect is limited. Yes, it is impossible to lower the temperature below the raw material decomposition temperature. In addition, there are problems such as the structure of the CVD apparatus and the substrate boat becoming complicated, and uniform cooling is not possible, and no practical problem has been solved.

[0021]

As described above, in the conventional hot wall type CVD apparatus and CVD method, the CV
Since the temperature was controlled by a resistance heater from the outside of the D reaction tube, basically only the silicon substrate could not be partially heated to a high temperature.

In the conventional thin film forming apparatus, the same amount of film deposition as on the silicon substrate occurs on the side wall of the reaction vessel 141 and the like, and the deposit is peeled off and adheres to the silicon substrate, and the deposited film on the substrate is removed. There was a disadvantage that defects occurred.

Further, the concentration of the source gas decreases toward the downstream side of the apparatus, and it becomes impossible to maintain the reaction rate-determining condition. As a result, the amount of film deposited on the downstream side decreases, and the composition and thickness of the deposited film decrease. In addition to non-uniformity such as changes in the surface area, there is a problem that good step coverage cannot be maintained.

In addition, frequent cleaning is required because the deposits (deposits other than on the substrate) generate dust. In the case of cleaning with an acid such as hydrochloric acid or nitric acid, washing with water, drying, etc. Requires a great deal of time and effort, and during that time, there is a problem that the operation as a thin film growth apparatus is stopped.

For this reason, it has not been possible to mass-produce a fine and highly integrated semiconductor integrated circuit device using a metal oxide having a high dielectric constant. SUMMARY OF THE INVENTION An object of the present invention is to provide a thin film forming apparatus having a high operating rate, capable of partially heating only a substrate to be deposited such as a silicon substrate, and a film quality and film thickness uniformity using the same. An object of the present invention is to provide a thin film forming method with good properties.

[0026]

In order to solve the above-mentioned problems, a thin-film forming apparatus according to the present invention provides a reaction vessel for accommodating a substrate on which a thin film is to be formed, and a reaction gas supplied into the reaction vessel. A gas supply mechanism, a gas discharge mechanism for discharging a reaction gas from the reaction vessel, and a heating mechanism for heating the inside of the reaction vessel, wherein the heating mechanism includes a resistance heating mechanism and a high-frequency heating mechanism It is characterized by the following. Further, the high-frequency heating mechanism is formed at a fixed distance from the outer periphery of the reaction vessel, and the resistance heating mechanism is formed outside the high-frequency heating mechanism and further away from the outer periphery of the reaction vessel. And

In the method for forming a thin film according to the present invention,
Placing a substrate on which a thin film is to be formed on a substrate boat in a reaction vessel, heating the semiconductor substrate and the substrate boat to a first temperature, and then heating only the substrate to the first temperature. A step of raising the temperature to a higher second temperature and a step of supplying a source gas into the reaction vessel to form a thin film on the substrate.

The source gas is Ba, Sr, Bi,
The thin film contains at least one of Ti, Ta, Zr, and Pb, and the thin film contains at least one of barium strontium titanate, strontium titanate, strontium bismuth tantalum oxide, and lead zirconate titanate.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view showing a main part of a thin film forming apparatus according to a first embodiment of the present invention.

FIG. 1 is a sectional view of a main part of a hot wall type CVD apparatus, wherein 141 is a quartz bell jar type reaction vessel having an open lower part, and a lower part of which is provided with a Kalretz O-ring 143 via a Kalretz O-ring 143. And a manifold 142 made of stainless steel. On the manifold 142 inside the reaction vessel 141, a cylindrical quartz inner pipe 144 is attached substantially parallel to the side wall of the reaction vessel 141 and separated by a predetermined distance to rectify the gas and improve the heat uniformity. The lower portion of the manifold 142 is connected via a Kalretz O-ring 145 so that a stainless steel cap 146 covers the lower side. The reaction vessel 141, the manifold 142, and the stainless steel cap 146 keep the inside of the reaction vessel 141 airtight. I'm dripping. A vertical drive mechanism 170 is connected to a lower portion of the stainless steel cap 146, whereby the stainless steel cap 146 is supported and can be moved up and down.

At the center of the stainless steel cap 146, a stainless steel cap 146 is inserted via a sealing material (not shown).
A rotating mechanism 147 that penetrates the inside of the quartz tube 144 is attached to the inside of the reaction vessel 141 above the rotating mechanism 147. A plurality of silicon substrates can be placed on the substrate boat 149 in parallel and at equal intervals.

The carrier gas supply pipes 1221 and 1231, the raw material gas supply pipe 1 are provided on one side of the manifold 142.
131 are connected to each other to form a gas supply mechanism.
An exhaust port 153 is connected to the other side surface, and the distal end thereof is connected to an exhaust pump 154 via a pressure regulator 155.
To form a gas discharge mechanism.

A carrier gas (Ar, oxygen) whose flow rate is controlled is supplied to the carrier gas supply pipes 1221 and 1231 via the mass flow controllers 122 and 123.

On the other hand, the source gas supply pipe 1131 is connected to the gas nozzles 151 and 152 inside the manifold. The gas nozzles 151 and 52 are distributed nozzles provided with a number of gas outlets between the inner tube made of quartz and the substrate boat 149 so that the raw material gas can be ejected to the substrate boat 149 side, and a fixed distance from the substrate boat. It is fixed separately.

At the end of the raw material gas supply pipe 1131 are connected the organic metal liquid raw material containers 101, 102, and 103 made of stainless steel.
₁₁ H ₁₉ O ₂ ) ₂ (hereinafter abbreviated as Ba (THD) ₂ ), S
r (C ₁₁ H ₁₉ O ₂ ) ₂ (hereinafter abbreviated as Sr (THD) ₂ ), Ti (C ₁₁ H ₁₉ O ₂ ) ₂ (i-OC ₃ H ₇ ) ₂ (hereinafter Ti (THD) ₂ (i —OPr) ₂ (where THD is 2,2,6,6-tetramethyl-3,5-heptanedion
e, that is, ((CH ₃ ) ₃ CCO) ₂ CH— stands for THF as a solvent (THF: tetrahydrofuran = C
Raw material is dissolved is stored in the ₄ H ₈ O). Each of the above raw materials is pumped by a carrier gas (Ar) from the organic metal liquid raw material containers 101, 102, and 103, mixed in a desired raw material ratio in an organic metal mixing manifold 111, and weighed by an organic metal weighing micropump 112. It is vaporized at once by the high-temperature organometallic vaporizer 113. An Ar carrier gas pipe (not shown) is connected to the vaporizer 113, and an Ar gas controlled at a desired flow rate is supplied. The vaporized organometallic raw material is transported by this Ar gas, and introduced into the reaction vessel 141 as a raw material gas through a raw material gas supply pipe 1131 heated to 250 ° C. by heating. Organometallic vaporizer 11
The pipes beyond 3 are placed in a thermostat (not shown) or a ribbon heater (not shown) is wound to enable heating.

On the other hand, at a predetermined distance from the outer surface of the side wall of the reaction vessel 141, a resistance heating heater (resistance heating mechanism) 150 made of Super Kanthal is mounted on the portion where the substrate boat 149 is mounted so as to make one or more rounds around the outer circumference of the reaction vessel 141. Almost correspondingly installed. This resistance heater 150
Can be energized and heated by a power supply unit (not shown), whereby the entire substrate boat 149 can be heated to a uniform temperature. Although these resistance heaters are shown as an integral unit, it is preferable to divide the substrate into three or four parts and to control the temperature independently of each other so as to suppress variations in the temperature of the substrate boat. .

Further, a high-frequency heater (high-frequency heating mechanism) 160 is provided between the resistance heater 150 and the outer surface of the side wall of the reaction vessel 141 in a range narrower than the area where the resistance heater 150 is mounted, substantially corresponding to the substrate boat installation portion. ,
Like the resistance heater 150, the heater is mounted so as to make one or more turns at a predetermined distance from the outer periphery of the reaction vessel 141. A high-frequency shield plate 161 made of stainless steel is provided between the high-frequency heater 160 and the resistance heater 150 to prevent high-frequency waves from propagating outward during high-frequency heating. With this configuration, the high frequency is cut off by the high frequency shielding plate 161 and transmitted only to the inside of the reaction vessel 141.

According to the thin film forming apparatus according to the first embodiment of the present invention described above, since the high frequency heater 160 is provided in addition to the resistance heater 150 as the heating means, the reaction vessel 14 is heated by the resistance heater 150.
1 is heated at the same time as high-frequency heater 150
Only materials that can be heated by high-frequency induction can be selectively further heated to obtain a partially high temperature. Thus, for example, if the material to be heated is subjected to high-frequency induction heating such as a silicon substrate, only that portion can be selectively heated to a higher temperature than its surroundings. Although the high-frequency heater 160 is installed inside the resistance heater 150 in the first embodiment, the positional relationship between the resistance heater 150 and the high-frequency heater 160 is not limited at all, and is alternately arranged on the same circumference. It may be arranged in. Further, the resistance heater 160 may be provided inside the high-frequency heater 160.

Further, in this embodiment, the high-frequency heater 160
Is a manifold 142 supporting the reaction vessel 141.
Is made of stainless steel and has conductivity, so that a shielding plate 161 is also provided below the high-frequency heater 160 so as not to heat it.
It is possible to adjust the degree of shielding to keep it at ~ 240 ° C. By performing such an adjustment, the condensation of the raw material vapor on the gas contact surface of the manifold can be prevented, and the usage efficiency of the raw material gas can be further increased.

(Second Embodiment) Next, as a second embodiment of the present invention, a thin film forming method using the thin film forming apparatus described in the first embodiment will be described with reference to FIG. The case where a BST thin film is formed by the above-described apparatus will be described in detail as an example.

The base substrate on which the thin film is to be formed is thermally oxidized 8
A 50-nm-thick Ru film was formed on an inch silicon substrate by a sputtering method. First, the silicon substrate is placed at a predetermined position of the substrate boat 149,
Introduced within. Up and down drive mechanism 1 for mounting the substrate
The manifold was lowered by 70, and the substrate boat 149 was taken out of the reaction vessel 141 to the outside. Then, after the twelve silicon substrates are placed at predetermined positions on the substrate boat 149, the manifold 142 is raised by the vertical drive mechanism 170 to make the inside of the reaction vessel 141 airtight. The inside of the reactor was evacuated, then Ar gas was introduced into the reactor at a flow rate of 100 sccm, and O ₂ gas was introduced into the reactor at a flow rate of 500 sccm. The reactor was heated by a resistance heater 150 to set the temperature in the reactor to 240 ° C. Further, the temperature of the silicon substrate was set to 420 ° C. by the high frequency heater 160. At this time, since only the silicon substrate is conductive and receives high-frequency induction, the temperature is raised to 420 ° C., but the reaction vessel 141, the inner tube 144, and the substrate boat 149 made of quartz are used.
Since the gas nozzles 151 and 152 are all insulators, they are not heated at a high frequency.

As a result of measuring the temperature of the reaction vessel 141 and the silicon substrate with a radiation thermometer, the temperature of the inner tube 144, the substrate boat 149, and the gas nozzles 151 and 152 is controlled to 240 ° C. It was confirmed that the temperature was maintained at 420 ° C. In addition, it was confirmed that the plurality of mounted silicon substrates remained in a temperature distribution of ± 2 ° C. or less irrespective of their positions.

The pressure in the reaction vessel 141 was set to 0.5 Torr by the pressure controller 155. Desired pressure and temperature
(In this case, 0.5 Torr, 420 ° C. in the silicon substrate part), and then Ba, Sr, and Ti raw materials were introduced. Composition ratio of each raw material,
The flow rate is set so that the Ba: Sr composition ratio of the film to be formed is 1: 1 and (Ba +
The operation of the mixing manifold 111 was set in advance so that the composition ratio of Sr): Ti was 1: 1 and the control flow rate of the micropump was set to 0.6 sccm. Vaporizer 113
Was 230 ° C., and the heating temperature of the raw material gas introduction pipe 1131 in the thermostat was 240 ° C. Under these conditions, Ba, Sr,
A BST thin film was formed by introducing a Ti raw material gas. The film formation was completed by stopping the introduction of the BST raw material gas into the reaction vessel 141. Next, in order to crystallize the deposited BST thin film, while only Ar and O ₂ are flowing in the reaction vessel 141, the output of the high-frequency heater 160 is increased, and only the silicon substrate temperature is increased up to 650 ° C. at 100 ° C./min. The temperature was increased at a rate of temperature increase, and heat treatment was performed for 20 minutes. Also at this time, the reaction vessel 141 made of quartz, the inner tube 144, the substrate boat 149, the gas nozzles 151, 15
2 is an insulator and cannot be heated at high frequencies. Actually, the temperature of these insulators also rises due to radiation and conduction from the deposition substrate heated to 650 ° C. by the high-frequency heater, but does not exceed 400 ° C. After the heat treatment,
After waiting for the cooling time, the substrate to be processed was taken out of the apparatus. Next, the silicon substrate on which the thin film was formed by the above method was analyzed. As a result, B
The film thickness of ST was 20 nm, and the composition was found to be Ba _0.5 Sr _0.5 TiO ₃ by X-ray fluorescence analysis as originally designed. The uniformity of the film thickness and composition on the substrate surface was ± 4%, The variation between the substrates was ± 6%, indicating that it was significantly improved compared to the past. In addition, after the formation of the thin film was completed, as a result of examining the inside of the CVD apparatus,
Inner tube 144, substrate boat 149, gas nozzle 151, 1
52 had no change in appearance, and no condensation, decomposition, or deposition of the raw material was observed. As a result, the particle contamination on the silicon substrate was reduced to 100 particles or less per substrate, indicating that the generation of dust was suppressed. Further, when the same thin film is continuously formed by using the same thin film forming apparatus without cleaning the apparatus, the same result as described above is obtained. 100 or less per sheet was maintained. Reduction of particle contamination is an indispensable requirement for reducing defective cells when miniaturizing elements and manufacturing semiconductor devices with high yield. Furthermore, suppressing aggregation and deposition of the raw materials leads to higher utilization efficiency of the raw materials and higher controllability of the thickness and composition of the film to be deposited, and as a result, the thin film can be made extremely thin. Thus, a highly integrated and fine semiconductor device can be realized.

In the second embodiment, the silicon substrate is transported into the reaction vessel 141, and then the reaction vessel 141 is heated by the resistance heater 150.
It may be heated to 240 ° C. In this case, after the silicon substrate is transferred, only the silicon substrate is heated by the high-frequency heater 160 and the deposition can be started after the temperature is stabilized, so that the processing time can be reduced. Similarly, when the silicon substrate is taken out of the reaction tube, only the silicon substrate needs to be cooled, so that it takes only a short time and the silicon substrate can be taken out of the apparatus quickly.

(Third Embodiment) Next, a thin film forming method according to a third embodiment of the present invention will be described. However, the thin film forming apparatus used in the third embodiment is the same as the apparatus used in the second embodiment, and the description is omitted. In the method of forming a thin film according to the present embodiment, only portions different from the second embodiment will be described.

In the third embodiment, the temperature set by the resistance heater 150 is 240 ° C., which is the same as that of the second embodiment, but the silicon substrate heating temperature by the high frequency heater 160 during BST film formation is 600 ° C. And higher. Thus, the heat treatment after the BST film formation was omitted. This is because the BST film is formed at a high temperature and has already been crystallized immediately after the film formation, so that a crystal heating treatment is not required.

In the case of this embodiment, the high-frequency heater 16
In the state where the temperature of the silicon substrate is heated to 600 ° C. by the temperature of 0, the adjacent substrate boat 1 is radiated or conducted.
49 and the temperature of the gas nozzles 151 and 152 also rise,
It is difficult to keep the temperature below ° C. Then, the organic metal raw material vapor is decomposed by these temperature rises, and the substrate boat 149 and the gas nozzles 151 and 152 emit B
ST adhesion occurs.

However, also in this case, the temperature of the substrate boat 149 and the gas nozzles 151 and 152 can be maintained at 400 ° C. or less, and the adhesion amount is several tens of the deposition amount on the silicon substrate maintained at 600 ° C. That's only one part. Further, since the temperature changes of the inner pipe 144, the substrate boat 149, and the gas nozzles 151 and 152 are not so large from the loading of the silicon substrate to the unloading thereof, unlike the case where the silicon substrate is heated to a high temperature by the resistance heater 150, the deposit due to the difference in thermal expansion and the like. The occurrence of peeling is suppressed as much as possible. Therefore, the number of depositions increases, and even when film deposition occurs, dust generation does not relatively increase.

According to this embodiment, in addition to the effects described in the second embodiment, crystallization is performed simultaneously with the formation of a thin film, so that a high-quality crystal can be obtained. The process can be shortened because it can be omitted.

(Fourth Embodiment) Next, a thin film forming apparatus according to a fourth embodiment of the present invention will be described with reference to FIGS.

FIG. 2 is a sectional view of a principal part of the thin film forming apparatus according to the present embodiment. The same parts as those in FIG. FIG. 3 is a schematic view of a part of the thin film forming apparatus according to the present embodiment.

In this embodiment, only 151 gas nozzles are connected to the source gas supply pipe. Then, with the substrate boat 149 at the center, the gas nozzle 151
A stainless steel re-diffusion prevention plate 162 is placed in a portion facing the.

As shown in the sketches of FIGS. 2 and 3, the anti-re-diffusion plate 162 is formed in a semi-cylindrical shape so as to face the gas nozzle 151 and surround the substrate boat 149.
It is fixed on a stainless steel cap 146. The source gas is blown out from the gas nozzle 151 and passed over the silicon substrate on the substrate boat 149. Thus, the re-diffusion prevention plate 162 is
By the movement of the stainless steel cap 146, the structure can be moved together with the substrate boat.

In the thin film forming apparatus according to this embodiment,
By disposing a rediffusion prevention plate 162 that can be heated by applying a high frequency to the periphery of the silicon substrate, the raw material gas that has passed without decomposing on the silicon substrate can be effectively decomposed, and BST of other parts can be reduced. Attachment can be reduced as much as possible. Further, since the re-diffusion preventing plate 162 is fixed on the stainless steel cap 146, it can be easily moved to the outside of the reaction vessel 141 by moving the stainless steel cap 146, and can be easily removed and replaced when the BST is attached. , Washing is possible. In this case, the reaction vessel 14
1 Since there is no need to wash the main body, there is no need for washing and drying, and there is no need to stop the operation of the thin film forming apparatus.

In this embodiment, the rediffusion preventing plate 162 is used.
Is installed separately from the substrate boat 149, but it is also possible to adopt a structure integrated with the substrate boat. Normally, the substrate boat is exchange-cleaned for each CVD. Therefore, according to this configuration, the re-diffusion preventing plate 162 can be exchange-cleaned at the same time.

The shape of the diffusion preventing plate is not limited to that shown in FIG. 3, and the effect of preventing re-diffusion can be further enhanced by increasing the surface area by increasing the complexity. Further, the re-diffusion prevention plate 162 is not limited to stainless steel, but may be any electrical conductor that receives high-frequency induction.

(Fifth Embodiment) A thin film forming method according to a fifth embodiment of the present invention will be described in detail with reference to FIGS.

The description of the same parts in this embodiment as those in the second embodiment will be omitted. The silicon substrate is transported to the reaction vessel 141 shown in FIG. 2, and the temperature of the entire reaction vessel is maintained at 240 ° C. by the resistance heater 150. At the same time, when heating is performed by the high-frequency heater 160, the re-diffusion preventing plate 162 is maintained at 420 ° C. together with the silicon substrate. As a result, when the source gas is sufficiently supplied,
Film deposition on the re-diffusion prevention plate 162 is substantially the same as that on the deposition substrate. However, in this case, since the deposition is performed on the downstream side of the flow of the raw material gas, the utilization efficiency of the raw material gas does not decrease and no problem such as dust generation occurs.

In this embodiment, in addition to the effects described in the above-described second embodiment, unreacted source gas once blown out from the gas nozzle and passed between the deposition substrates is decomposed on the rediffusion prevention plate 162. -Since the material is deposited, it is possible to eliminate the source gas that collides with and re-diffuses the reaction vessel 141 and the like and flows backward. The thickness and composition of the deposited film between silicon substrates and within the same silicon substrate while maintaining the reaction rate-determining conditions are maintained. The distribution can be improved.

In each of the above embodiments, a silicon substrate has been described as an example. However, the present invention is not limited to this, but may be a compound semiconductor substrate such as gallium arsenide as long as it can be heated at a high frequency. You may. further,
Needless to say, even a substrate such as sapphire that cannot be heated by high frequency can be implemented as long as a film that can be heated by high frequency is formed on a part of the substrate.

In each of the above embodiments, the reaction vessel and the like are formed using quartz. However, the present invention is not limited to this, and any material that is not heated at a high frequency can be used. . Further, even when a material which can be heated by high frequency is partially used, it is needless to say that the present invention does not depart from the present invention as long as the degree of heating is sufficiently small.
In addition, the present invention can be carried out by changing various components without departing from the spirit of the present invention.

Further, the thin film formed on the substrate is not limited to BST, but can be similarly applied to the formation of PZT, STO, BTO, tantalum dioxide or the like. The source gas used at that time can be appropriately selected according to the film to be formed.

[0063]

As described above, according to the present invention, it is possible to maintain only a substrate on which a thin film is grown at a high temperature. In addition, it is possible to significantly reduce the amount of deposits attached to the reaction vessel side walls and the like, and to significantly reduce the amount of attachments to the substrate surface due to the separation. In addition, by making the reaction gas concentration uniform on the upstream side and the downstream side, it is possible to realize a uniform deposition film and a uniform film thickness. Further, the cleaning of the reaction vessel becomes almost unnecessary, and the operation rate of the thin film forming apparatus can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a thin film forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a thin film forming apparatus according to a third embodiment of the present invention.

FIG. 3 is a schematic view of a main part of a thin film forming apparatus according to a third embodiment of the present invention.

FIG. 4 is a sectional view of a main part of a conventional thin film forming apparatus.

[Explanation of symbols]

101, 102, 103 Organometallic liquid raw material container 111 Liquid raw material mixing manifold 112 Liquid raw material weighing micro pump 113 Liquid raw material vaporizer 122, 123 Mass flow controller 1131 Raw material gas supply pipe 1221, 1231 Carrier gas supply pipe 141 Reaction vessel 142 manifold 143 Ring 144 Inner tube 145 O-ring 146 Cap 147 Rotating mechanism 148 Heat insulation tube 149 Substrate boat 150 Resistance heater 151, 152 Gas nozzle 153 Exhaust port 154 Exhaust pump 155 Pressure regulator 160 High frequency heater 161 High frequency shield plate 162 Anti-diffusion plate 170 Vertical drive mechanism

Claims (4)

[Claims] 1. A reaction container for accommodating a substrate on which a thin film is to be formed, a gas supply mechanism for supplying a reaction gas into the reaction container, a gas discharge mechanism for discharging a reaction gas from the reaction container, and the reaction container A thin-film forming apparatus comprising: a heating mechanism for heating the inside; wherein the heating mechanism includes a resistance heating mechanism and a high-frequency heating mechanism. 2. The high-frequency heating mechanism is formed at a predetermined distance from the outer periphery of the reaction vessel, and the resistance heating mechanism is formed outside the high-frequency heating mechanism and further away from the outer circumference of the reaction vessel. The thin film forming apparatus according to claim 1, wherein: 3. A step of placing a substrate on which a thin film is to be formed on a substrate boat in a reaction vessel; a step of raising the temperature of the semiconductor substrate and the substrate boat to a first temperature; A step of raising a temperature to a second temperature higher than the first temperature, and a step of forming a thin film on the substrate by supplying a source gas into the reaction vessel. Method. 4. The method according to claim 1, wherein the source gas is Ba, Sr, Bi, Ti,
4. The method according to claim 3, wherein the thin film contains at least one of Ta, Zr, and Pb, and the thin film contains at least one of barium strontium titanate, strontium titanate, strontium bismuth tantalum oxide, and lead zirconate titanate. The method for forming a thin film according to the above.