Patent Application
20130291797
The present invention relates to a vaporizer that vaporizes a film forming liquid material included in a carrier gas, and to a film deposition apparatus including the vaporizer.
Conventionally, such a technique is known in which in a film deposition apparatus that forms a film on the surface of a semiconductor wafer using a CVD device or the like including an MOCVD device, a carrier gas including a film forming liquid material is supplied to a vaporizer and the film forming liquid material included in the carrier gas is vaporized in the vaporizer.
Moreover, in such a vaporizer, a heater is disposed on the outer periphery of the vaporizer or disposed on the outer periphery of a pipe to supply a carrier gas into the vaporizer, and a film forming material included in a carrier gas is vaporized by the heat of the heater (Patent Documents 1 to 3, for example).
Furthermore, Patent Document 4 discloses a technique in which a liquid raw material is introduced into a carrier gas, the liquid raw material is formed into fine particles in the order of micron or less (one micron or less) and dispersed in the carrier gas (in the following, a carrier gas in which a liquid raw material is dispersed is referred to as a raw material gas), the raw material gas is introduced into a vaporizer and vaporized, and then a film is formed in a reaction chamber. At this time, for the purpose of preventing that only a solvent is vaporized to cause clogging at an outlet, for example, a unit that cools the outlet is provided. Moreover, in order to disperse a liquid raw material into a carrier gas in smaller particles, a preferable condition for the flow rate of the carrier gas is a flow rate ranging from 50 to 340 m/sec.
However, when a film is formed by the technique, ripples are sometimes produced on the surface of a film. Moreover, the existence of particles is recognized in a film or on a surface. Furthermore, the composition of a film is sometimes shifted from a target composition. In addition, a carbon content is sometimes increased.
Moreover, in the description of Patent Document 4, in the case where an STO film is formed, for example, a liquid raw material cannot be vaporized unless the temperature is set to a temperature of 300° C. or more near a coupling to another device near the outlet of the vaporizer. Namely, it is necessary to set a temperature much higher than a theoretical temperature. However, for example, in the case where a coupling is heated at a temperature of 300° C., an O-ring at the coupling is demanded to have high heat resistance, and a metal ring is inevitably used in some cases.
Patent Document 5 describes a vaporizer for a liquid raw material for forming a film in which the shape of a vaporization unit is in a shape spreading on the input side of a gas and a heater is disposed in the vaporizer.
In Patent Document 4, for example, in the case where an STO film is formed, a liquid raw material cannot be vaporized unless the temperature is set to a temperature of 300° C. or more near the coupling to another device near the outlet of the vaporizer. Namely, it is necessary to set a temperature much higher than a theoretical temperature. However, for example, in the case where the coupling is heated at a temperature of 300° C., the O-ring at the coupling is demand to have high heat resistance, causing a problem in that a metal ring is inevitably used in some cases.
In Patent Document 5, since the shape of the vaporization unit is in a shape spreading on the input side of a gas, such problems arise in that a gas flow stagnates at a portion in a concave curve shape, in that a jet stream deviates due to the disturbance of an air current and it is difficult to perform sufficient vaporization, and in that attachments are accumulated on a portion in a concave curve shape to produce particles, for example.
It is an object of the present invention is to provide a vaporizer that can reduce ripples, particles, and a carbon content of a film and can supply a raw material capable of forming a film having a desired composition.
Moreover, it is an object to provide a film deposition apparatus, with the use of such a vaporizer, that can facilitate vaporization in the vaporizer and can suppress the production of ripples or the like in forming a film.
It is an object of the present invention to provide a vaporizer that can perform sufficient vaporization without heating more than necessary.
An invention according to one embodiment is a vaporizer including: a vaporizer main body into which a carrier gas having a film forming liquid material dispersed is introduced; and a heater main body disposed in an inside of the vaporizer main body. The heater main body is configured in order of an inlet portion, a peripheral portion, and a discharge portion, and a shape of the inlet portion of the heater main body is in a cone or in a polygonal pyramid.
The present inventors investigated the causes of the problems in the conventional techniques by conducting various experiments. As a result, the present inventors found a cause that a liquid material dispersed in a carrier gas might be fed into a reaction chamber as the liquid material is insufficiently vaporized, and attempted to solve the problems. As a result, it was confirmed by experiment that non-vaporization is not always prevented when the heating temperature is simply increased. Moreover, an increase in the temperature adversely affects a coupling, for example.
In conducting various experiments, the present inventors happened to find that when a heater is disposed on a passage of a carrier gas in which a liquid raw material is dispersed, the problems can be solved immediately. The present inventors then made the present invention.
In another embodiment, the heater main body is disposed on an extending line of an inlet portion for the carrier gas.
The area of the inlet portion for a raw material gas into the vaporizer ranges from 0.1 to 1 mm2, and the carrier gas in which a raw material liquid solution is dispersed is introduced from the inlet portion into the vaporizer. The flow rate is increased at a portion on the extending line of the gas flow, and time for which heat is received in the vaporizer is reduced. Therefore, preferably, an internal heater is disposed in such a way that the internal heater shields the passage of the raw material gas.
In a different embodiment, a discharge portion for a gas after vaporized is disposed on an extending axis of the inlet portion for the carrier gas.
Although the length (H in
In yet another embodiment, a cross sectional area of a passage around a peripheral portion at a portion where the heater disposed in the inside exists ranges from 0.8 to 1.2 of a cross sectional area of a passage without the heater.
In a further embodiment, a cross sectional area of a passage around a cone of the inlet portion at a portion where the heater disposed in the inside exists ranges from 0.8 to 1.2 of a cross sectional area of a passage without the heater in the inlet portion of the heater main body.
For the relationship between the cross sectional area of a portion indicated by S0 in
It is noted that as for the cross sectional area S1 of the passage, the cross sectional area of a passage at a portion where the heater exists is the cross sectional area of a passage around the heater in a cylindrical shape in
Furthermore, preferably, for the internal heater, a slope portion in a cone or in a polygonal pyramid is provided on the raw material gas inlet portion side for preventing a turbulent flow. Preferably, the cross sectional area of the gas inlet portion corresponding to the slope portion is also the same as S1.
Therefore, a slope portion is formed also on the outer shape of the vaporizer along the slope portion of the internal heater. It is noted that preferably, a slope is also provided on the discharge portion side.
In yet a different embodiment, the carrier gas including the film forming liquid material is introduced into the vaporizer main body at a velocity ranging from 50 m/sec to 350 m/sec.
In order that a liquid raw material is chopped and atomized in small particles (an outer diameter of 1 μm or less) and the particles are dispersed in a carrier gas, for preferable use, the liquid raw material is introduced into the carrier gas at a velocity of 50 m/sec to 350 m/sec (more particularly, at subsonic speed (0.6 to 0.75 of sonic speed). When the present invention is applied in the case under the conditions, the vaporization rate can be significantly improved.
Ina different embodiment, a unit configured to cool the inlet portion for the carrier gas is provided.
The passage of the carrier gas, the liquid raw material, and the passage of the raw material gas to the inlet portion of the raw material gas are cooled (particularly, they are cooled at a temperature of the boiling point of a solvent or less), so that clogging can be prevented at the inlet portion, and the present invention is particularly effective in the case of such cooling.
In a further embodiment, a second heater is disposed on an outer periphery on a discharge side of the vaporizer main body.
The second heater is disposed, so that a temperature difference on the vaporization passage can be further reduced.
In a separate embodiment, a cone of the inlet portion of the heater main body, a cone height/a cone base diameter ranges from 0.5 to 1. Here, when the cone height/the cone base diameter is less than 0.5, the cone becomes flat to cause a problem in that the cone becomes a resistance to a carrier gas flow, whereas when the cone height/the cone base diameter is more than 1, the height of the cone is increased to cause a problem in that the length of the vaporizer device is increased.
Also described is a film deposition apparatus including any of the vaporizer embodiments.
At this time, preferably, the vaporizer main body includes an inlet portion formed near an inlet port for a carrier gas and expanding its opening in the discharging direction of the carrier gas, a body continued to the inlet portion, and a discharge portion shrinking its opening from the body to the discharging direction of the carrier gas, and the heater main body integrally includes an inlet portion formed near the inlet port for the carrier gas and expanding its opening in the discharging direction of the carrier gas, a body continued to the inlet portion, and a discharge portion shrinking its opening from the body to the discharging direction of the carrier gas.
Moreover, preferably, the vaporizer main body and the heater main body are configured in such a way that the locations of the inlet portion, the peripheral portion, and the discharge portion of the vaporizer main body correspond to the locations of the inlet portion, the peripheral portion, and the discharge portion of the heater main body at almost the same locations.
Furthermore, preferably, the vaporizer main body and the heater main body have a nearly perfect circle in a flat cross sectional shape intersecting with the discharging direction of the carrier gas, and the centers of the circles are coaxially disposed.
It is noted that as described above, a second heater may be disposed on the outer periphery on the discharge side of the vaporizer main body.
It is possible to provide a vaporizer that can reduce ripples, particles, and a carbon content of a film and can supply a raw material capable of forming a film having a desired composition.
It is possible to provide a vaporizer that can further reduce a temperature difference on a vaporization passage.
It is possible to provide a film deposition apparatus that can facilitate vaporization in the vaporizer and can suppress the production of ripples or the like in forming a film.
According to the present invention, it is possible to provide a vaporizer that can perform sufficient vaporization without heating more than necessary and can facilitate temperature management.
Next, a vaporizer according to an embodiment of the present invention will be described with reference to the drawings.
As illustrated in
It is noted that as illustrated in
Moreover, the vaporizer 1 includes a pipe connecting unit 2 disposed on the upper part in the drawing to charge the carrier gas described above, a vaporizer main body 3 connected to the pipe connecting unit 2, and a heater main body 4 disposed in the vaporizer main body 3. It is noted that the lower part of the vaporizer main body 3 in the drawing is freely used according to purposes such as being connected SH to a pipe connecting unit similar to the pipe connecting unit 2 and being connected to a film deposition apparatus (a chamber).
The vaporizer main body 3 is divided into an upper part and a lower part in the drawing, and has nearly a perfect circle shape in the cross section (the horizontal cross section) as illustrated in
The heater main body 4 is divided into an upper part and a lower part in the drawing, and has nearly a perfect circle shape in the cross section (the horizontal cross section) as illustrated in
It is noted that in the embodiment, the heater main body 4 is configured in such a way that the inlet portion 3a of the vaporizer main body corresponds to the inlet portion 4a of the heater main body at almost the same locations, the cylindrical portion 3b of the vaporizer main body corresponds to the cylindrical portion 4b of the heater main body at almost the same locations, and the discharge portion 3c of the vaporizer main body corresponds to the discharge portion 4c of the heater main body at almost the same locations. Moreover, in the heater main body 4, a passage length L near the inlet portion 3a of the vaporizer main body is set to a distance in which a carrier gas (a mist) spreads and flattens (5 cm, for example) in the vaporization passage 5, so that more uniform vaporization can be performed.
Thus, the vaporization passage 5 of a small temperature difference can be formed in such a way that the temperature in the vaporization passage 5 is at a temperature of about 290° C. near the inlet portion 3a of the vaporizer main body (nearly equal the passage length L) and at a temperature of about 270° C. on the passage after the inlet portion 3a, for example.
Moreover, a second heater may be disposed on the outer periphery on the discharge side of the vaporizer main body 3, for example, in order to eliminate this temperature difference.
In the configuration described above, a carrier gas (a mist) supplied from a pipe connecting unit 2 into a vaporization passage 5 passes through near the outer periphery of a cylindrical portion 4b of a heater main body while being spread at an inlet portion 4a of the heater main body, and the carrier gas is recombined at a discharge portion 4c of the heater main body.
Thus, the passage length of the vaporization passage 5 can be set longer than a length H of the vaporizer main body 3, the dwell time of a carrier gas can be kept longer while implementing the downsizing of the vaporizer main body 3, and sufficient vaporization of the carrier gas can be implemented as well as the effect of direct heating by the heater main body 4.
In the present invention, in forming an STO film, for example, the temperature in the inside of a vaporization chamber was set at a temperature of 250° C. for forming a film. The temperature at the coupling of the vaporizer to another device (a film deposition apparatus, for example) was also at a temperature of 250° C. Ripples, particles, and a carbon content of the film were significantly reduced even under the conditions, and in addition to this, a shift of a composition from a desired composition was enabled to be reduced.
An STO film (a film A) was formed as a shape of a portion (the inlet portion) of the heater on the inlet port side of the vaporizing chamber was formed in a cone.
It is noted that in the example, a cone height/a cone base diameter was set to 0.6.
In the example, the cross sectional area of the passage around the peripheral portion was set the same as the cross sectional area of the passage without the heater.
On the other hand, an STO film (a film B) was similarly formed as the inlet portion of the heater was formed in a cylinder.
In the film A, a shift of SrTiO3 in stoichiometry was a half of a shift of SrTiO3 in the film B or less.
Moreover, the number of particles and the carbon content of the film A were a quarter of those of the film B or less.
In the case where the cross sectional area of the passage around the peripheral portion was set in a range of 0.8 to 1.2 of the cross sectional area of the passage without the heater, the effect of the present invention was excellent more than in the case where the cross sectional area of the passage around the peripheral portion was less than 0.8 of the cross sectional area of the passage without the heater and in the case where the cross sectional area of the passage around the peripheral portion was more than 1.2 of the cross sectional area of the passage without the heater.
According to the present invention, it is possible to provide a vaporizer that can improve the vaporization effect in the inside of the vaporizer and can facilitate temperature management, and it is possible to implement the improvement of the performance of a film deposition apparatus using the vaporizer.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-284916 | Dec 2010 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2011/079727 | 12/21/2011 | WO | 00 | 7/24/2013 |
