JP3960987B2 - Reaction vessel - Google Patents

Description

Detailed Description of the Invention

TECHNICAL FIELD OF THE INVENTION

  The present invention relates to a substrate processing apparatus for processing a substrate in a reaction chamber used in one step of a semiconductor device manufacturing process, and more particularly to an improved gas introduction unit for supplying a gas to a substrate.

Conventional technology

FIG. 10 shows a vertical substrate processing apparatus as an example of a conventional technique for processing a substrate in a reaction chamber by CVD (Chemical Vapor Deposition) or one of them, ALD (Atomic Layer Deposition). A brief description will be given with reference.
FIG. 10 is a schematic cross-sectional view of the inside of a reaction tube which is a reaction chamber in a vertical substrate processing apparatus according to a conventional technique.
Inside the reaction tube 106, a boat 108 on which wafers 107 are stacked in multiple stages is inserted as a substrate to be processed, and a gas nozzle 101 is used as a gas introduction part for processing the wafer 107 in the reaction tube 106. Is provided.
By providing a plurality of gas nozzle holes 103 (five examples are shown in FIG. 10) in the gas nozzle 101, a processing gas travels in the gas nozzle 101 from the gas introduction port 105 and passes through each gas nozzle hole 103 to each wafer. 107.
The gas supplied to each wafer 107 is structured to be exhausted from the exhaust port 118 to the outside of the reaction tube 106 after processing such as forming a desired film on each wafer 107.

However, when the opening areas of the gas nozzle holes 103 provided in the gas nozzle 101 are all the same, the gas flow rate and flow velocity supplied from the gas nozzle holes 103 to the wafers 107 are from the upstream side near the gas inlet 105. The problem of decreasing towards the far downstream was found.
That is, in the apparatus for collectively processing a plurality of wafers 107 shown in FIG. 10, when considering from the viewpoint of supplying gas to each wafer, the gas nozzle 101 appears to be each one of each wafer. Although it seems that the gas is uniformly supplied to the wafer 107, in reality, there is a difference in gas flow rate and flow velocity, and not all the wafers 107 are supplied under the same conditions.
For example, the five gas nozzle holes 103 provided in the gas nozzle 101 are designated as the first, second,..., Fifth from the upstream near the inlet 105 of the gas nozzle 101 to the far downstream, and are supplied from each gas nozzle hole 103. Q1>q2>...> Q5 where q1, q2,.
Further, also in the gas flow rate, the gas from the first gas nozzle hole 103 is the fastest, and then gradually slows down to the second and third.
As a result, non-uniformity occurs in the flow rate and flow rate of the gas supplied to each wafer 107.
In this case, non-uniformity occurs in the film formation between the stacked wafers 107 in the process processing of the wafer, which greatly depends on the gas supply amount.

Returning to FIG. 10 again, the cause of the non-uniformity in the gas supply amount will be considered.
In the gas nozzle 101 in a state where gas is supplied to the wafer 107, the gas flow rate between the inlet 105 and the first gas nozzle hole 103 is q00, and the gas pressure is p0. Next, the gas flow rate between the first and second gas nozzle holes 103 is q01, and the gas pressure is p1. Similarly, the flow rate of gas between the (n-1) th and nth gas nozzle holes 103 is q0 (n-1), and the gas pressure is pn-1.
On the other hand, the flow rate of the gas ejected from the nth gas nozzle hole 103 is defined as qn.

At this time, the gas flow rate qn (n = 1, 2,...) Ejected from the plurality of gas nozzle holes 103 having the same opening area provided from the upstream side to the downstream side of the gas nozzle 101 is expressed by the following equation (1):
q1>q2>...>qn-1> qn (1)
It decreases from the upstream gas nozzle hole to the downstream gas nozzle hole.
This is because the gas flowing from the upstream side to the downstream side in the gas nozzle 101 has its gas flow rate q0 (n-1) reduced by the gas flow rate qn ejected from the gas nozzle hole 103 when passing through the gas nozzle hole 103. Therefore, the gas flow rate q0n of the gas after passing through the gas nozzle hole 103 is expressed by q0n = q0 (n-1) -qn (2)
It decreases as it goes from the upstream side to the downstream side.

At this time, the gas density of the fluid in the gas nozzle 101 decreases by the amount of gas flow ejected from the gas hole from upstream to downstream. Since there is a correlation between the gas density and the gas pressure, the gas pressure pn at the portion in the gas nozzle 101 corresponding to the gas nozzle hole 103 decreases from the upstream to the downstream as shown in Equation (3).
p1>p2>...>pn-1> pn (3)
For this reason, the gas flow rate qn ejected from each gas nozzle hole 103 is not equal. Further, when the opening area of the gas nozzle hole 103 is S, the gas flow velocity V ejected from the gas nozzle hole is
V = qn / S (4)
It can be expressed. Since the gas flow rate qn injected from each gas nozzle hole 103 is not equal, the flow velocity of the gas injected from each gas nozzle hole 103 is different if the opening area of the nozzle hole is the same. Therefore, in the conventional gas nozzle 101 described above, the gas flow rate and the gas flow rate of the gas injected from each gas nozzle hole 103 are different, so that it is considered that the gas cannot be uniformly supplied to each loaded wafer.

Two precursor solutions have been considered for the above-mentioned problems.
A first solution is to increase the opening area of the gas nozzle hole 103 from upstream to downstream, and to increase the opening area to increase the gas flow rate that decreases as it goes downstream. However, even if an attempt is made to equalize the gas flow rate depending on the size of the opening area, the gas flow rate varies depending on the size of the opening area from Equation (4). Therefore, the gas ejected from each gas nozzle hole 103 still does not eliminate the nonuniformity of the gas flow rate.

The second solution is to set the gas nozzle itself so that the gas pressure in the gas nozzle 101 at the site corresponding to each gas nozzle hole does not change even if gas is ejected from each gas nozzle hole 103 from upstream to downstream. It is also conceivable that the gas flow rate of gas ejected from each gas nozzle hole 103 is made equal by configuring with a large-capacity gas nozzle capable of storing a large amount of gas that can be ignored. However, it is impractical to increase the capacity of the gas nozzle itself so that the gas pressure in the gas nozzle 101 is not affected by the amount of gas ejection because the space in the reaction chamber in which the gas nozzle is stored is limited.
The above-mentioned problems are not limited to wafers but are widely common to substrates.

  Accordingly, an object of the present invention is to provide a substrate processing apparatus that can achieve processing uniformity between substrates by uniformly supplying a gas from a viewpoint different from the above-described structure.

The first means for solving the above-mentioned problem is
A reaction chamber for storing stacked substrates;
A gas introduction part for introducing a substrate processing gas provided in the reaction chamber in the direction in which the substrates are stacked;
A buffer chamber having a plurality of gas supply ports provided along the direction in which the substrates are stacked and configured to supply a processing gas introduced from the gas introduction unit from the plurality of gas supply ports; This is a substrate processing apparatus.

  By providing this configuration, the substrate processing apparatus according to the present invention can equalize the flow rate of the gas supplied from the gas introduction unit in the buffer chamber with a non-uniform flow rate. Gas can be supplied uniformly.

The second means is the substrate processing apparatus according to the first means,
In the substrate processing apparatus, opening areas of a plurality of gas supply ports provided in the buffer chamber are substantially equal.

  In addition to the first means, by providing a gas supply port having the same opening area, the gas supply to the substrate can be made more uniform.

The third means is the substrate processing apparatus according to the first or second means,
The substrate processing apparatus is characterized in that an electrode for plasma generation is provided in the buffer chamber.

By using a configuration in which an electrode for plasma generation is provided in the buffer chamber, active species are generated by plasma at a position close to the substrate and at a uniform pressure, and more active species can be generated uniformly. Can be supplied to the substrate.
(Embodiment of the Invention)

  First, a film forming process using a CVD method and an ALD method, which is one of them, will be briefly described as an example of a process process for a substrate performed in the embodiment of the present invention. .

In the CVD method, under a certain film forming condition (temperature, time, etc.), one kind (or more kinds) of raw material gas used for film formation is mixed and supplied onto a substrate, and a gas phase reaction is performed. This is a technique for performing film formation by adsorption and reaction on a substrate using only surface reaction or surface reaction.
In the ALD method, under one film formation condition (temperature, time, etc.), two kinds (or more) of raw material gases used for film formation are alternately supplied onto the substrate one by one, and one atomic layer unit. In this method, the film is adsorbed by using a surface reaction to form a film.

  In other words, for example, in the case of forming a SiN (silicon nitride) film, high-quality film formation is possible at a low temperature of 300 to 600 ° C. using DCS (dichlorosilane) and NH 3 (ammonia) in ALD. On the other hand, in the case of normal CVD, the film forming temperature is relatively high at 600 to 800 ° C. As for gas supply, a plurality of types of reactive gases are alternately supplied (not supplied simultaneously) in ALD, while a plurality of types of gases are supplied simultaneously in normal CVD. The film thickness is controlled by the number of cycles of the reactive gas supply in ALD. (For example, if the film formation rate is 1 mm / cycle, when a film of 20 mm is formed, the process is performed for 20 cycles.) In contrast, CVD is different in that it is controlled by time.

Here, an embodiment of the present invention will be described with reference to FIGS.
In addition, the same code | symbol was attached | subjected and shown to the common location in FIGS.

First, the outline of the mechanism of the vertical substrate processing apparatus according to the present invention will be briefly described with reference to FIG.
FIG. 4 shows a case in which a plurality of substrates to be processed having a diameter of 200 mm are loaded in a reaction tube made of quartz as a reaction chamber, and a CVD process or one of them, an ALD process, is used as a process process. It is the figure which showed the external appearance of the example of the vertical type substrate processing apparatus which performs a film process.
The vertical substrate processing apparatus includes a main body 60 and a utility unit 61 that supplies power and the like to the main body.

Inside the main body 60, there are provided a reaction tube 6 as a vertical reaction chamber for performing a process on the wafer, and a heater 16 for appropriately heating the reaction tube 6. Below the reaction tube 6, a boat 8 for taking wafers into and out of the reaction tube 6 and a boat elevator 36 for moving the boat 8 up and down are installed.
When it is necessary to generate plasma in the reaction tube 6, an electrode 52 is provided in the reaction tube 6, and high-frequency power is applied to the electrode 52 from the high-frequency power source 51 via the RF matching unit 53.

Further, inside the main body 60, a cassette shelf 34 for temporarily storing a cassette in which wafers to be supplied to the boat 8 are stored, and wafers to be processed are supplied from the cassette shelf 34 to the boat 8 to be processed wafers. Is provided.
The cassette loader 35 carries the wafer cassette 32 between the cassette shelf 34 and the I / O stage 33 that delivers the wafer cassette 32 to the outside world.
The I / O stage 33 is installed on the front side of the apparatus, and exchanges the cassette 32 in which wafers are stored with the outside of the apparatus.

Here, the operation of the above-described vertical substrate processing apparatus will be briefly described.
A cassette 32 in which wafers are stored is set on the I / O stage 33.
The cassettes 32 set on the I / O stage 33 are sequentially connected to a cassette shelf 34 by a cassette loader 35.

In the present embodiment, 25 wafers are stored in the cassette 32.
The wafer transfer device 38 unloads the wafer from the force set shelf 34 and transfers it to the quartz boat 8. Since 100 boats can be loaded with the boat 8, the transfer operation by the wafer transfer device 38 is repeated several times.
When the transfer of the wafer to the boat 8 is completed, the boat 8 is raised by the boat elevator 36 and inserted into the reaction tube 6, and then the inside of the reaction tube 6 is kept airtight.

  The gas in the reaction tube 6 is exhausted by a pump from an exhaust port (not shown), and when a predetermined pressure is reached, the boat 8 is rotated by a rotating mechanism (not shown) to form a film with a constant flow rate inside the reaction tube 6. Supply processing gas. The supplied processing gas is maintained at a constant pressure by a pressure adjusting mechanism (not shown). At this time, the wafer inside the reaction tube 6 is held at a predetermined temperature by the heater 16.

In this way, the process of forming a film on the wafer proceeds, the details of which will be described later.
At this time, when the film formation process is performed by the plasma CVD method or the ALD method which is one of them, a high frequency power is applied to the electrode 52 from the high frequency power source 51 through the RF matching unit 53, and the film forming gas is added. An operation for generating plasma and activating the film-forming gas is also performed, and the details will be described later.
When the film forming process is completed, the wafer boat 8 is lowered from the reaction tube 6 by the boat elevator 36 and is carried to the I / O stage 33 via the wafer transfer device 38, the cassette shelf 34, and the cassette loader 35. Is carried out of the apparatus.

  Next, using the above-described vertical substrate processing apparatus, hereinafter, 1) an embodiment using the CVD method for the film forming process, 2) an embodiment using the ALD method for the film forming process, 3) Different embodiments using the ALD method for the film forming process will be described.

1) Embodiment using CVD method for film forming process FIG. 2A is a schematic cross-sectional view of a reaction tube in a vertical substrate processing apparatus according to this embodiment, and FIG. These are the aa 'longitudinal cross-sectional views of (a).
In FIG. 2A, a heater 16 is provided on the outer periphery of a reaction tube 6 which is a vertical reaction chamber, and a plurality of wafers 7 are stacked and placed as substrates to be processed on the inner side. . Further, in the arc-shaped space between the inner wall of the reaction tube 6 and the wafer 7, a buffer chamber 17 is provided on the inner wall above the lower portion of the reaction tube 6 along the loading direction of the wafer 7. A buffer chamber hole 3 as a gas supply port is provided at the end of the wall adjacent to the wafer 7. The buffer chamber hole 3 opens toward the center of the reaction tube 6.
The gas nozzle 2 provided in the gas introduction portion is provided at the end opposite to the end provided with the buffer chamber hole 3 in the buffer chamber 17. It is arranged along. The gas nozzle 2 is provided with a plurality of gas nozzle holes 4.

  On the other hand, as shown in FIG. 2B, the outer periphery of the reaction tube 6 is covered with a heater 16. The reaction tube 6 is supported on the furnace port flange 25, and the furnace port of the furnace port flange 25 is sealed with a furnace port cap 27.

  A boat 8 on which a plurality of wafers 7 are placed in multiple stages at the same interval is provided in the center of the reaction tube 6. The boat 8 can enter and exit the reaction tube 6 by the boat elevator mechanism described above. ing. In addition, a rotating mechanism 15 for rotating the boat 8 is provided below the boat 8 in order to improve the uniformity of processing.

  When the boat 8 enters the reaction tube 6 and the film formation process is performed on the wafers 7, the wafers 7 placed in multiple stages are placed at an equal distance from the buffer chamber 17.

  A buffer chamber 17 is provided along the inner wall of the reaction tube 6, and the gas nozzle 2 is disposed inside the buffer chamber 17 from the lower side to the upper side of the side surface of the reaction tube 6.

The gas nozzle 2 and the buffer chamber 17 are provided with the gas nozzle hole and the buffer chamber hole described above. An example of the opening state of these holes will be described with reference to FIG.
FIG. 3A is a perspective view of the gas nozzle shown in FIG. 2, and FIG. 3B is a perspective view of the buffer chamber shown in FIG.
The gas nozzle 2 shown in FIG. 3A is a pipe having a circular cross section, and a gas nozzle hole 4 is provided on the side of the pipe from the almost uppermost part of the gas nozzle 2 to the bottom of the buffer chamber 17. The openings are arranged in a straight line from the side toward the downstream side, and the opening area is from the upstream side (downward in FIG. 3) to the downstream side (upward in FIG. 3) when viewed from the gas inlet. It is getting bigger.
The buffer chamber 17 shown in FIG. 3B is a pipe having a circular arc cross section, and the buffer chamber hole 3 having the same opening area is formed along the stacking direction of the wafer 7 at the end of the curved surface inside. They are arranged in a straight line.

Here, it returns to FIG.2 (b) again.
An exhaust port 18 connected to an exhaust pump (not shown) is provided on the side surface of the lower portion of the reaction tube 6.

  Here, a film forming process on the wafer 7 by the CVD method in the reaction tube 6 will be described with reference to FIGS.

  A processing gas which is a raw material for film formation is supplied to the gas nozzle 2 from the gas inlet 5. The gas nozzle 2 is provided with the plurality of gas nozzle holes 4 described above, and jets gas into the buffer chamber 17. However, as described as a preliminary solution, it is difficult to make the flow rate and flow velocity of the gas ejected from the plurality of gas nozzle holes 4 the same only by controlling the opening area of the gas nozzle holes 4.

Therefore, in the present invention, by increasing the opening area of the gas nozzle hole 4 from the downstream side to the upstream side, first, the gas having the same flow rate is ejected from each gas nozzle hole 4 although there is a difference in the gas flow velocity. . Then, the gas ejected from each gas nozzle hole 4 is not ejected into the reaction tube 6 but is ejected into the buffer chamber 17 and introduced once, and the flow velocity difference of the gas is made uniform.
That is, in the buffer chamber 17, the gas ejected from each gas nozzle hole 4 is ejected from the buffer chamber hole 3 into the reaction tube 6 after the particle velocity of each gas is reduced inside the buffer chamber 17. During this time, the gas ejected from each gas nozzle hole 4 exchanges the kinetic energy of each other, so when ejected from each buffer chamber hole 3, it was possible to obtain a gas having a uniform flow rate and flow velocity. .

The uniform gas supply amount in the buffer chamber 17 will be further described with reference to FIG.
FIG. 1 is a schematic cross-sectional view showing the relationship among a gas nozzle, a buffer chamber, and a wafer inside a reaction tube of a vertical substrate processing apparatus according to the present invention.
In FIG. 1, a buffer chamber 17 is provided in the reaction tube 6, the gas nozzle 2 is provided inside the buffer chamber 17, and an exhaust port 18 for exhausting the gas in the reaction tube 6 to the outside of the chamber is provided. ing.
Further, in the reaction tube 6, a boat 8 on which wafers 7 are mounted (in FIG. 1, 5 sheets are mounted) is provided adjacent to the buffer chamber 17.
The gas nozzle 2 and the buffer chamber 17 are provided with a gas nozzle hole 4 and a buffer chamber hole 3 (five each in FIG. 1), and the opening area of the gas nozzle hole 4 is set to each gas nozzle hole. 4, the upstream side is small as viewed from the gas introduction port 5 and is increasing toward the downstream side so that the amount of gas jetted from 4 is the same.

With this configuration, the first, second,..., Fifth from the upstream near the inlet 5 in the gas nozzle 2 toward the far downstream, the gas flow rates supplied from the gas nozzle holes 4 are Q1, Q2,. When, Q1 = Q2 = ... = Q5.
However, as explained in the precursor solution, the gas flow rate from the first gas nozzle hole 4 is the fastest, and thereafter, the gas flow rate is gradually slowed down to the second and third.
The gas flows Q1 to Q5 having the same flow rate but different flow rates are once introduced into the buffer chamber 17. During this period, the gas flow of Q1 to Q5 is made uniform in flow rate difference by exchanging kinetic energy, and the pressure in the buffer chamber 17 becomes substantially uniform.

As a result, when the flow rate of the gas flow ejected from each buffer chamber hole 3 is R1, R2,... R5, the pressure in the buffer chamber 17 is uniform even if each buffer chamber hole 3 has the same opening area. Therefore, R1 = R2 =... = R5 and the flow speeds thereof are also equal.
Furthermore, each opening position of the buffer chamber hole 3 is set to have the same pitch as that of the adjacent wafers 7 and is further provided so as to supply gas to the space between the mounted wafers 7. This is preferable because the uniformized gas can be efficiently supplied to the wafer 7.
The gas with uniform flow velocity and flow rate is efficiently supplied to the wafer 7, so that the film formation state between the wafers 7 becomes uniform, and the process processing speed of the wafer 7 is greatly improved. it can.

  In the above description, the CVD method is described as an example of the configuration of the gas nozzle and the buffer chamber. However, this configuration can be similarly applied to the ALD method.

2) Embodiment using ALD method for film formation process An embodiment in which film formation is performed by ALD method will be described more specifically than the case of CVD method.

Also when the film is formed on the wafer 7 by the ALD method, the above-described vertical substrate processing apparatus can be used. However, in the case of the ALD method, when it is required to activate the processing gas with plasma or the like, necessary equipment and operations are added to this process.
Hereinafter, the case where film formation is performed by the ALD method will be described with reference to FIGS.

5A, 5B, and 5C show, from different sides, the appearance and the inside of a reaction tube that is a reaction chamber in a vertical substrate processing apparatus according to the present invention, which is used in film formation by the ALD method. FIG. 6 is a cross-sectional view taken along the line AA.
5A, 5B, and 5C, (a) shows the appearance of the reaction chamber, (b) and (c) show the longitudinal section of the reaction chamber, and the heater, wafer, boat, reaction tube, The joint with the furnace port flange and the boat rotation mechanism are omitted.

In FIG. 6, a heater 16 is provided on the outer periphery of the reaction tube 6, and a wafer 7 is stacked and placed on the inside as a plurality of substrates to be processed. Further, in the arc-shaped space between the inner wall of the reaction tube 6 and the wafer 7, a buffer chamber 17 is provided along the stacking direction of the wafer 7 on the inner wall of the reaction tube 6, and the end of the wall adjacent to the wafer is provided. The part is provided with a buffer chamber hole 3.
In addition, an exhaust port 18 is provided at the bottom of the reaction tube 6.

Here, in the reaction tube described in FIG. 2 (a), the gas nozzle is disposed at the end opposite to the end provided with the buffer chamber hole in the buffer chamber. In such a reaction tube, a gas supply chamber 43 is provided as a gas introduction part instead of the gas nozzle, and a gas introduction port 5 is provided at the lower part thereof.
The partition between the gas supply chamber 43 and the buffer chamber 17 is provided with a gas supply chamber hole 47 having the same configuration as the gas nozzle hole provided in the gas nozzle described above, and is provided in the buffer chamber 17. The opening positions of the buffer chamber holes 3 are set at the same pitch as the adjacent wafers 7.
As a result, in the same manner as described in “1) Embodiment Using CVD Method for Film Forming Process”, the gas is once introduced from the gas introduction unit, and the gas is uniformly distributed to each loaded wafer 7. Can be supplied to.

  Further, in the present embodiment, the electrode 52 is disposed in the buffer chamber 17 so as to be protected from the upper part to the lower part by the electrode protection tube 50, and this electrode 52 is connected to the high frequency power supply 51 through the RF matching unit 53. ing. As a result, the electrode 52 can generate the plasma 14 in the buffer chamber 17.

In addition, in the present embodiment, the reaction gas buffer chamber 42 is provided on the inner wall of the reaction tube 6 that is rotated about 120 ° from the opening position of the buffer chamber hole 3. The reaction gas buffer chamber 42 shares the gas supply species with the buffer chamber 17 when a plurality of types of gases are alternately supplied to the wafer 7 one by one in the film formation by the ALD method.
Similarly to the buffer chamber 17, the reaction gas buffer chamber 42 also has reaction gas buffer chamber holes 48 at the same pitch at positions adjacent to the wafer, and a reaction gas inlet 45 at the bottom. However, unlike the buffer chamber 17, the gas supply chamber 43 and the electrode 52 are not provided, and the reaction gas buffer chamber hole 48 has a configuration in which the opening area increases from the upstream side toward the downstream side.

  An exhaust port 18 is provided in the lower part of the reaction tube 6, but when supplying a plurality of types of gases one by one to the wafer 7 in the above-described film formation by the ALD method, The internal gas can be exhausted from the reaction tube 6.

FIG. 5A shows the appearance and the inside (indicated by a broken line) of the reaction tube 6 when the buffer chamber 17 is viewed from the front direction.
In the reaction tube 6, a buffer chamber 17 is provided from the top to the bottom, and a gas supply chamber 43 is provided adjacent to the buffer chamber 17. In the buffer chamber 17, an electrode 52 covered with the electrode protection tube 50 is disposed from the upper part to the lower part, and the gas inlet 5 is provided in the lower part of the gas supply chamber 43.

  The electrode protection tube 50 has a structure in which an electrode 52 having an elongated structure can be inserted into the buffer chamber 17 while being isolated from the atmosphere of the buffer chamber 17. Here, since the inside of the electrode protection tube 50 has the same atmosphere as the outside air (atmosphere), the electrode 52 inserted into the electrode protection tube 50 is oxidized by heating of a heater (not shown). Therefore, the inside of the electrode protection tube 50 is provided with an inert gas purge mechanism for filling or purging with an inert gas such as nitrogen to keep the oxygen concentration sufficiently low.

A reaction gas buffer chamber 42 is provided from the buffer chamber 17 around the inner wall of the reaction tube 6 from the upper portion to the lower portion, and a reaction gas inlet 45 is provided at the lower portion thereof.
In addition, an exhaust port 18 is provided at a lower portion of the buffer chamber 17 where the inner wall of the reaction tube 6 is turned in a direction opposite to the reaction gas buffer chamber 42.

FIG. 5B shows the inside of the reaction tube 6 when the buffer chamber hole 3 and the reaction gas buffer chamber hole 48 are viewed from the front side.
In the reaction tube 6, a buffer chamber 17 and a gas supply chamber 43 adjacent to the buffer chamber 17 are provided from the upper part to the lower part. In the buffer chamber 17, a position adjacent to a wafer (not shown) is provided from the upper part to the lower part. The buffer chamber holes 3 having the same opening area are provided at the same pitch. The buffer chamber hole 3 has the same opening area on the wall of the buffer chamber 17 having the same thickness.

  A reaction gas buffer chamber 42 is provided from the buffer chamber 17 around the inner wall of the reaction tube 6 from the upper portion to the lower portion. In the reaction gas buffer chamber 42, reaction gas buffer chamber holes 48 are provided at the same pitch at positions adjacent to the wafer (not shown) from the upper part to the lower part. Note that the opening area of the reaction gas buffer chamber hole 48 is configured to increase from the upstream side to the downstream side, and from bottom to top in FIG.

FIG. 5C is a longitudinal cross section of the reaction tube 6 that is vertically cut so that a gas supply chamber hole 47 provided in the gas supply chamber 43 appears on the front surface.
In the reaction tube 6, a gas supply chamber 43 is provided adjacent to the buffer chamber 17 from the upper part to the lower part. The partition wall between the buffer chamber 17 and the gas supply chamber 43 is provided with a gas supply chamber hole 47 extending from the upper part to the lower part than the position adjacent to the wafer (not shown). The reason why the gas supply chamber hole 47 is opened to the lowermost end of the buffer chamber 17 is to prevent a gas stagnation portion from being generated in the buffer chamber 17.
In addition, the opening area of the gas supply chamber hole 47 has a configuration that becomes larger from the upstream side to the downstream side of the gas flow, similarly to the gas nozzle hole provided in the gas nozzle described in FIG. .

Here, film formation by the ALD method on the wafer 7 in the reaction tube 6 will be described with reference to FIGS.
In this film formation example, active species of ammonia (NH3) and dichlorosilane (SiH2Cl2) are alternately supplied as processing gases, and an SiNx film (silicon nitride film) is formed by atomic layer film formation. How to do will be described.

  100 wafers 7 are loaded into the reaction tube 6 and the inside of the reaction tube 6 is held in an airtight state. The inside of the reaction tube 6 is evacuated by a pump (not shown) through the exhaust tube 18 and is kept at a constant temperature in the range of 300 to 600 ° C. by adjusting the temperature of the heater 16.

The supply of ammonia from the gas inlet 5 to the gas supply chamber 43 is started.
The gas supply chamber hole 47 provided in the gas supply chamber 43 has an opening area gradually from the upstream side to the downstream side of the gas flow so that the flow rate of ammonia ejected from here into the buffer chamber 17 becomes the same amount. It is provided to be larger.
Therefore, the ammonia that passes through the gas supply chamber hole 47 and is ejected into the buffer chamber 17 is fast in the upstream side and slow in the downstream side, but the flow rate is the same in all the gas supply chamber holes 47.
The ammonia ejected into the buffer chamber 17 is once introduced here, the difference in flow velocity is made uniform by exchanging kinetic energy with each other, and the pressure inside the buffer chamber 17 becomes uniform.

Ammonia is introduced into the buffer chamber 17 so that the pressure in the space between the pair of electrode protection tubes is uniform, and the rod-like shape inserted into the two electrode protection tubes 50 provided in the buffer chamber 17. When high-frequency power from the high-frequency power source 51 is supplied to the electrode 52 via the RF match Kugu unit 53, plasma 14 is generated between the electrode protection tubes 50.
In the buffer chamber 17, ammonia is converted into plasma to generate active species of ammonia. At this time, since the plasma is generated in a state where the pressure in the buffer chamber 17 is uniform, the distribution of the electron temperature and the plasma density of the plasma that affects the generation of the active species is also uniform. Active species can be generated.
Active species generated by the action of plasma and the like have a lifetime, and if the distance between the plasma generation unit and the wafer 7 is long, it is deactivated before being supplied to the wafer 7 and contributes to the reaction on the wafer 7. Since the amount of active species to be reduced is remarkably reduced, it is desirable to generate plasma in the vicinity of the wafer 7.
According to this configuration, active species of ammonia are generated in the vicinity of the wafer 7 in the buffer chamber 17, so that a large amount of the generated active species of ammonia can be efficiently supplied to the wafer 7.
The interval between the two electrode protection tubes 50 is preferably set to an appropriate distance so that the generation of the plasma 14 is limited to the inside of the buffer chamber 17, and is preferably about 20 mm. The plasma 14 may be generated anywhere in the buffer chamber 17, but it is desirable that the gas introduced into the buffer chamber 17 passes through the plasma, preferably between the buffer chamber hole 3 and the gas supply chamber hole 47. It may be provided so as to be positioned.

Further, the distance between the electrode protection tube 50 and the buffer chamber hole 3 is adjusted to an appropriate interval so that the plasma 14 generated in the buffer chamber 17 does not diffuse and leak outside the buffer chamber 17.
As a result, only the electrically neutral ammonia active species is supplied from the buffer chamber hole 3 to the wafer 7, and damage due to the charge-up of the wafer 7 can be avoided.

As described above, since the buffer chamber holes 3 provided in the buffer chamber 17 all have the same opening area, the active species of ammonia supplied to the wafer 7 is supplied at a uniform flow rate and a uniform flow rate. A uniform film forming process is performed on each wafer 7.
Further, since the buffer chamber hole 3 is provided in the middle of the interval between the wafers 7 placed in multiple stages, the processing gas is sufficiently supplied to each of the loaded wafers 7.

  In the ALD method in which different types of processing gases are alternately supplied to form an ultrathin film one layer at a time, the supply of the active species of ammonia can be achieved by appropriately setting the pressure and temperature inside the reaction tube 6. When an ultrathin film containing N atoms is formed for one layer, a limit is applied, and the film thickness does not increase any more.

  When an ultrathin film containing N atoms is formed on the entire surface of the wafer 7, the RF power applied to the electrode 52 is turned off, and the supply of ammonia is also stopped.

  Next, these gases are exhausted from the exhaust port 18 while purging the inside of the reaction tube 6 with an inert gas such as N2 or Ar. Then, when the concentration of the active species of ammonia in the reaction tube 6 is sufficiently lowered, the supply of the inert gas is stopped, and dichlorosilane is introduced into the reaction gas buffer chamber 42 from the reaction gas inlet 45.

  In the reaction gas buffer chamber 42, a reaction gas buffer chamber hole 48 whose opening area gradually increases from upstream to downstream of the reaction gas inlet 45 is provided toward the center of the reaction tube 6. As a result, the dichlorosilane supplied to the wafer from the reaction gas buffer chamber hole 48 has the same flow rate but is ejected into the reaction tube 6 although the flow velocity is different.

Of course, in the supply of dichlorosilane, instead of the reaction gas buffer chamber 42, another set of gas supply chamber 43 similar to that used for ammonia supply and the buffer chamber 17 adjacent thereto is installed in the reaction tube 6. It is preferable to supply dichlorosilane from the buffer chamber hole 3 provided here, since both the flow rate and the flow rate can be made uniform.
However, in this embodiment, the supply of dichlorosilane is sufficient in the wafer 7 if the reaction gas buffer chamber 42 is used, which is simpler than the combination of the gas supply chamber 43 and the buffer chamber 17, and the gas flow rate is made equal. A uniform film forming process is possible.

  When particles containing Si are adsorbed on the surface of the wafer 7 in the form of an extremely thin film, the supply of dichlorosilane is stopped. Then, after purging the inside of the reaction tube 6 with an inert gas such as N2 or Ar, these gases are exhausted from the exhaust port 18 and when the concentration of dichlorosilane in the reaction tube 6 is sufficiently lowered, the inert gas is exhausted. Stop supplying.

  By this series of processes, a SiNx film of about 1 mm can be formed. Therefore, for example, when forming a 500-inch SiNx film on the wafer 7, the above process is repeated about 500 times.

Note that a boat (not shown) on which the wafer 7 is placed is rotated at a constant speed, so that even when gas is supplied from one side of the wafer 7, a more uniform film formation process over the entire surface of the wafer 7. Is realized. In this embodiment, it is sufficient that the rotational speed is 1 to 10 rpm.
Incidentally, when the boat is not rotated, the film thickness uniformity of the wafer 7 is about ± 5%, but when the boat is rotated, it is <± 1%.

3) Different Embodiments Using ALD Method for Film Forming Process FIG. 7 is a cross-sectional view of a reaction tube of a vertical substrate processing apparatus according to another embodiment of the present invention.
The reaction tube 6 shown in FIG. 7 has the same structure as the reaction tube 6 shown in FIG. 6, but in FIG. 6, the plasma generating electrode is disposed in the buffer chamber 17. 7, an ultraviolet lamp 54 for activating the gas and a reflection plate 58 for preventing the ultraviolet light from being irradiated outside the buffer chamber 17 are provided in combination.
The reactive gas is activated by the energy of light from the lamp 54.
The processing gas activated and activated in the buffer chamber 17 having the above configuration is ejected from the buffer chamber hole 3 toward the wafer 7, and film formation is performed on the wafer 7 by the ALD method described above.

FIG. 8 is also a cross-sectional view of a reaction tube of a vertical substrate processing apparatus according to another embodiment of the present invention.
The reaction tube 6 shown in FIG. 8 has the same structure as that of the reaction tube 6 shown in FIG. 7, but in FIG. 7, the reactive gas is activated by the energy of light. A heating wire (hereinafter referred to as a hot wire) 55 having an electric resistance value is heated to 1600 ° C. or higher by a power source 57 to activate a gas that has touched the hot wire.
As the hot wire 55 having an appropriate electrical resistance value and generating active species, a W (tungsten) wire of about 0.5 mm can be suitably applied.
The hot wire 55 is heated to 1600 ° C. or higher by the power of the power source 57 and is activated by the heat energy of the processing gas in contact with the hot wire 55.
The processing gas activated in the buffer chamber 17 having the above configuration is ejected from the buffer chamber hole 3 toward the wafer 7, and film formation is performed on the wafer 7 by the ALD method described above.

FIG. 9 is also a cross-sectional view of a reaction tube of a vertical substrate processing apparatus according to another embodiment of the present invention.
The reaction tube 6 shown in FIG. 9 has the same structure as the reaction tube 6 shown in FIG. 6, but in FIG. 6, the plasma generating electrode is disposed in the buffer chamber 17. In FIG. 9, a remote plasma unit 56 is arranged in the gas flow path further upstream of the gas inlet 5 through which the processing gas is introduced into the reaction tube 6, and plasma is generated in the gas passing therethrough. It is set as the structure which carries out.

The processing gas that passes through the remote plasma unit 56 reacts with the plasma to become active species, enters the activated species gas into the reaction tube 6 through the gas inlet 5 and passes through the gas supply chamber 43. It is supplied to the buffer chamber 17 and further supplied to the wafer 7 as a uniform gas from the buffer chamber hole 3 provided in the buffer chamber 17. Then, film formation is performed on the wafer 7 by the ALD method described above.
Here, an ICP coil or the like is preferably used as the remote plasma unit 56.
According to this configuration, compared to the apparatus of FIG. 6, the amount of active species supplied to the wafer is reduced and the processing efficiency is lowered, but it is used when the processing efficiency may be lowered.

  Gas is provided by providing a buffer chamber in which a processing gas introduced from a gas introduction unit is supplied from a plurality of gas supply ports when processing gas is supplied to the laminated substrate and processed. And the gas can be uniformly supplied to the stacked substrates.

It is typical sectional drawing inside the reaction tube of the substrate processing apparatus concerning this invention. It is a typical cross-sectional view of the reaction tube of the substrate processing apparatus concerning this invention. It is a perspective view of the gas nozzle and buffer chamber concerning this invention. It is a mechanism schematic diagram of a vertical substrate processing apparatus according to the present invention. It is a figure which shows the external appearance and the inside of the reaction tube of the substrate processing apparatus concerning this invention. FIG. 6 is a cross-sectional view taken along line AA in FIG. 5. It is a cross-sectional view of the reaction tube of the substrate processing apparatus which concerns on a different embodiment. Same as above Same as above It is typical sectional drawing inside the reaction tube of the substrate processing apparatus concerning the prior art.

Explanation of symbols

2. 2. Gas nozzle 3. Buffer chamber hole 4. Gas nozzle hole 5. Gas inlet 6. Reaction tube Wafer 8. Boat 18. Exhaust port Q1 ~ 4. Flow rate of gas ejected from the gas nozzle hole R1-4. Flow rate of gas ejected from the buffer chamber hole

Claims (4)

Form a reaction chamber that can accommodate multiple substrates,
A gas introduction part;
An elongated reaction vessel comprising a buffer chamber,
The gas introduction unit can introduce a processing gas into the buffer chamber, and is provided along the longitudinal direction of the reaction vessel.
The buffer chamber is provided inside the reaction vessel, has a plurality of gas supply ports provided along the longitudinal direction of the reaction vessel, and supplies the processing gas introduced from the gas introduction unit to the plurality of gas supplies. A reaction container which can be supplied to the reaction chamber from a mouth, and wherein the buffer chamber forms a space for accommodating an electrode for generating plasma. Form a reaction chamber that can accommodate multiple substrates,
Multiple buffer chambers;
A plurality of gas introduction portions capable of introducing process gas into the plurality of buffer chambers, respectively,
The plurality of buffer chambers are provided inside the reaction vessel, respectively, have a plurality of gas supply ports provided along the longitudinal direction of the reaction vessel, and are respectively introduced from the plurality of gas introduction units. A reaction container capable of supplying gas to the reaction chamber from the plurality of gas supply ports, wherein at least one of the buffer chambers forms a space for accommodating an electrode for generating plasma. The reaction container according to claim 2, wherein at least one of the plurality of gas introducing portions is provided along a longitudinal direction of the reaction container. Form a reaction chamber that can accommodate multiple substrates,
A gas introduction part;
An elongated reaction vessel comprising a buffer chamber,
The gas introduction unit is provided to introduce a processing gas into the buffer chamber,
The buffer chamber is provided inside the reaction vessel, has a plurality of gas supply ports provided along the longitudinal direction of the reaction vessel, and supplies the processing gas introduced from the gas introduction unit to the plurality of gas supplies. A reaction container which can be supplied to the reaction chamber from a mouth, and wherein the buffer chamber forms a space for accommodating an electrode for generating plasma.

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