Patent Application
20110023784
The present invention relates to an evaporator that supplies a source gas along with a carrier gas to a film deposition chamber of a film deposition apparatus.
Materials for use in semiconductor devices are now increasing their range from inorganic to organic substances. The organic substances having properties unobtainable from the inorganic materials may make it possible to further optimize production processes and characteristics of semiconductor devices.
Such organic materials include polyimide, which has higher adhesiveness and greater resistance against leakage current, and thus can be used as an insulation layer in semiconductor devices.
As a method of depositing such a polyimide film, there has been known a film deposition method employing vapor deposition polymerization, in which 4,4-Oxydianiline (ODA) and Pyromellitic Dianhydride (PMDA) as monomer source materials are used and polymerized in a chamber.
Because PMDA is likely to be sublimated, although PMDA is a solid source material, a film deposition apparatus of the polyimide is provided with a PMDA evaporator.
The PMDA evaporator generates a source gas by heating a source tank containing a solid source material, the interior of which is kept under vacuum. Especially, as a method of sublimating an organic compound having a sublimation property such as PMDA, a method of using carriers such as beads having the organic compound on their surfaces, which are supplied into a sublimation container, has been disclosed (see Patent Document 1, for example).
Patent Document 1: Japanese translation of PCT International Application No. 2005-535112
When the polyimide film is used as an insulation layer of semiconductor devices, it is required that the polyimide film has great density and high adhesiveness. To this end, when depositing the polyimide film, the evaporated PMDA needs to be continuously supplied at a constant flow rate. However, when PMDA gas (or vapor) obtained by heating to sublimate the solid PMDA in a sublimation container is supplied to a chamber, because an amount of the solid PMDA is reduced through sublimation and thus a surface area of the solid PMDA is reduced, it is difficult to continuously supply the PMDA gas at a constant amount to the chamber.
In the method described in Patent Document 1 to sublimate the organic compound, the organic compound that covers the carrier surfaces is heated through a heat medium such as a carrier gas. Because the organic compound has a large surface area, a sufficient amount of evaporated gas can be obtained. However, as the organic compound is being sublimated, a surface area of the organic compound is decreased, which makes it impossible to continuously and stably supply the evaporated organic compound at a constant flow rate to the chamber.
In addition, when the sublimation container is re-filled with the organic compound, the film deposition apparatus with the sublimation container needs to be brought to a halt according to the method of Patent Document 1, which makes it difficult to continuously supply the sublimated organic compound to the chamber.
The present invention provides an evaporator that is capable of continuously and stably supplying a source gas obtained by sublimating a solid source material.
A first aspect of the present invention provides an evaporator that sublimates a solid source material to generate a source gas to be supplied to a film deposition apparatus. The evaporator includes a heating part that heats and sublimates the solid source material to generate the source gas; a supplying part that is provided above the heating part and supplies the solid source material to the heating part; a gas introduction part to which a carrier gas that transports the source gas generated in the heating part is introduced; and a gas discharging part that discharges the generated source gas along with the carrier gas. The carrier gas introduced from the gas introduction part flows through the heating part.
A second aspect of the present invention provides an evaporator that sublimates a solid source material to generate a source gas to be supplied to a film deposition apparatus. The evaporator includes a heating part that heats and sublimates the solid source material to generate the source gas; a supplying part that is provided above the heating part and supplies the solid source material to the heating part; and a gas passage provided between the gas introduction part and the gas discharging part, the gas passage being provided below the heating part. The heating part includes a mesh part, and the carrier gas that flows through the gas passage contacts the solid source material via the mesh part.
According to embodiments of the present invention, there is provided an evaporator that is capable of continuously and stably supplying a source gas obtained by sublimating a solid source material. In the following, non-limiting embodiments of the present invention will now be described with reference to the accompanying drawings. In the drawings, the same or corresponding reference symbols are given to the same or corresponding members or components, and repetitive explanations may be omitted.
An evaporator according to a first embodiment of the present invention is to supply an evaporated PMDA to an apparatus for depositing a polyimide film through vapor deposition polymerization using ODA and PMDA as a source monomer.
As shown in
The supplying part 1 includes a source material storage part 5, a thermal insulation member 6a, and a source material introduction opening 7 that is closable and arranged above the source material storage part 5. In the supplying part 1 including the source material storage part 5, which may be referred to as the supplying part 1 (source material storage part 5), including the thermal insulation member 6a and the source material introduction opening 7, even when mainly the source material storage part 5 is meant, hereinafter, a powder source material RM of PMDA (referred to as a PMDA powder) is stored. The supplying part 1 supplies the PMDA powder RM stored in the source material storage part 5 to the heating part 2. The heating part 2 holds the PMDA powder RM supplied from the supplying part 1 and heats to sublimate the PMDA powder RM, thereby producing PMDA gas R. Carrier gas C is introduced from the gas introduction part 3 into the heating part 2. In addition, the PMDA gas R generated in the heating part 2 is discharged from the gas discharging part 4.
The supplying part 1 has a volume that allows a sufficient amount of the PMDA powder RM to be stored, as shown in
A volume of the supplying part 1 (source material storage part 5) may be greater than a volume of the heating part 2. To this end, a height of the supplying part 1 (source material storage part 5) may be greater than a height of the heating part 2, for example, as shown in
In addition, a part of a side wall of the supplying part 1 (source material storage part 5) is preferably made of the thermal insulation member 6a. This is because an amount of heat propagating from the heating part 2, which is arranged below the supplying part 1, toward a central part and an upper part of the supplying part 1 can be further reduced.
In this embodiment, the heating portion 2 has a container-like shape that has an open upper end and two opposing side surfaces made of mesh parts 8 (a first mesh part 8a, a second mesh part 8b). The mesh parts 8 are capable of keeping the PMDA powder RM within the heating part 2 and allows gaseous communication between an inside and an outside of the heating part 2. The mesh part 8 may be made of a metal mesh such as a stainless steel mesh.
When an average particle size of the PMDA powder falls within a range from 200 μm through 300 μm, the PMDA powder may include about 1% of PMDA particles having a particle size of 100 μm or less. When the PMDA powder having such particle size distribution is used, an average mesh opening size of the mesh parts 8 may be about 100 μm. Namely, the mesh parts 8 preferably have an opening size smaller than or equal to the average particle size of the source material powder. More preferably, the mesh parts 8 have an opening size smaller than or equal to a particle size of a source material powder whose content percentage is about 1% or less in the particle size distribution.
The open upper surface of the heating part 2 is in physical communication with the supplying part 1 (source material storing part 5), so that the PMDA powder RM stored in the supplying part 1 (source material storing part 5) falls due to the gravitational force G, and is held by the heating part 2. Therefore, even when the PMDA powders RM are consumed through sublimation to generate voids in the PMDA powders, the PMDA powders RM fall into the voids from the supplying part 1 (source material storing part 5), thereby filling the voids.
In this embodiment, a heating mechanism 9 is provided in a lower portion of the heating part 2 serving as a heat source of the heating part 2. The heating mechanism 9 includes, for example, a heating wire, which heats the PMDA powder stored in the heating part 2. In addition, the heating part 2, the gas introduction part 3, the gas discharging part 4, and the lower part of the supplying part 1 are surrounded by a thermal insulation member 60, which reduces heat dissipation toward an exterior. Therefore, the PMDA powder is efficiently heated by the heating mechanism 9.
Incidentally, as long as the PMDA powder stored in the heating part 2 can be heated, the heating mechanism 9 may be arbitrarily arranged.
The gas introduction part 3 includes a gas introduction pipe 11, a gas introduction opening 12, and a gas introduction chamber 13. The gas introduction chamber 13 is partitioned from the heating part 2 by the first mesh part 8a of the heating part 2. The gas introduction pipe 11 is connected at the gas introduction opening 12 to the gas introduction chamber 13 in order to introduce the carrier gas C that carries the PMDA gas R to the heating part 2.
The gas discharging part 4 includes a gas discharging chamber 14, a gas discharging opening 15, and a gas discharging pipe 16. The gas discharging chamber 14 is partitioned from the heating part 2 by the second mesh part 8b of the heating part 2, and arranged on the other side of the gas introduction chamber 13 with the heating part 2 therebetween. The gas discharging pipe 16 is connected at the gas discharging opening 15 to the gas discharging chamber 14 in order to guide the carrier gas that is carrying the PMDA gas R from the evaporator 10 to a film deposition apparatus (not shown).
With such a configuration, the carrier gas C flows through the gas introduction part 3, the heating part 2, and the gas discharging part 4 in this order. Therefore, the carrier gas C flows substantially exclusively through the heating part 2 arranged below the supplying part 1 (source material storage part 5), and rarely flows into the supplying part 1 (source material storage part 5) to contact the PMDA powder stored in the supplying part 1 (source material storage part 5). In addition, a flow direction of the carrier gas C is orthogonal to a direction along which the PMDA powder stored in the supplying part 1 (source material storage part 5) is supplied to the heating part 2, in this embodiment.
Next, effects (or advantages) of the evaporator 10 according to this embodiment are explained with reference to
A subsection (a) of
As shown, the carrier gas C flows into the heating part 2 from the gas introduction chamber 13 through the first mesh part 8a, and flows out from the heating part 2 to the gas discharging chamber 14 through the second mesh part 8b. In this situation, when the heating mechanism 9 (
When the PMDA powder RM1 stored in the heating part 2 is heated up to a temperature exceeding the sublimation temperature of PMDA, and maintained at the temperature, the PMDA powder RM1 is sublimated to produce the PMDA gas R, as shown in the subsections of
Incidentally, the first mesh part 8a and the second mesh part 8b are entirely arranged to be the opposing side surfaces of the heating part 2 in this embodiment as shown in
In addition, because PMDA powder RM2 stored in the supplying part 1 (source material storage part 5) in physical communication with the upper portion of the heating part 2 is not heated up to the sublimation temperature of PMDA, the PMDA powder RM 2 is rarely sublimated to produce the PMDA gas R. In other words, the PMDA powder RM1 stored in the heating part 2 is heated in this embodiment.
Incidentally, PMDA powder stored in and around the boundary between the heating part 2 and the supplying part 1 (source material storage part 5) may be heated up to a temperature higher than the sublimation temperature due to thermal propagation of the heat H from the heating part and thus may be sublimated. However, the PMDA gas is generated only from the PMDA powder stored near the boundary, and not generated from the entire PMDA powder stored in the supplying part 1 (source material storage part 5).
As the PMDA gas R is being generated in the heating part 2 as described above, the particle size of the PMDA powder RM1 becomes smaller, and thus voids may be produced within the PMDA powder RM1 stored in the heating part 2, as shown in a subsection (b) of
However, the voids are readily filled because the PMDA powder RM2 stored in the supplying part 1 (source material storage part 5) falls due to the gravitational force G, as shown in a subsection (c) of
Incidentally, while the subsection (c) of
In addition, because the volume of the supplying part 1 (source material storage part 5) is greater than the volume of the heating part 2, when a sufficient amount of the PMDA powder is stored in the supplying part 1 (source material storage part 5), the PMDA gas can be supplied to a chamber for a relatively long period of time without resupplying the PMDA powder RM.
In addition, even when a certain period of time has elapsed and a remaining amount of the PMDA powder RM is decreasing, the PMDA powder RM can be supplied from the source material introduction opening 7 during the production of the PMDA gas, because the source material introduction opening 7 is away from the heating part 2 and sublimation of the PMDA powder RM1 is not affected even if the source material introduction opening 7 is opened.
Next, a first modified example of the first embodiment is explained with reference to
The evaporator according to this modified example is different from the evaporator 10 according to the first embodiment mainly in terms of shapes of the supplying part (source material storage part) and the heating part, and the rest is substantially the same as the evaporator 10. The following explanation is focused on the differences.
Referring to
In addition, when the cross-sectional area is decreased from above to below, a higher pressure is applied to a lower portion, compared with a case where the cross section is constant in a vertical direction. Therefore, the PMDA powder can be efficiently supplied from the supplying part 1a (source material storage part 5a) to the heating part 2.
Additionally, the cross-sectional area of the heating part 2 may be relatively smaller in order to make the cross-sectional area of the supplying part 1a (source material storage part 5c) relatively larger than the cross-sectional area of the heating part 2. With this, the PMDA powder held in the heating part 2 can be maintained at a more constant temperature. Therefore, because the PMDA gas is generated from the entire PMDA powder amount in the heating part 2 and thus the PMDA powder uniformly disappears, the PMDA powder is uniformly supplied to the entire heating part 2 from the supplying part 1a (source material storage part 5a).
Moreover, when the cross-sectional area of the heating part 2 becomes small, the gas introduction chamber 13a can be made larger as shown in
In addition, while a part of the side wall of the source material storage part 5 is composed of the thermal insulation member 6a in the first embodiment, a thermal insulation member 6b may be provided in order to surround the source material storage part 5a.
Moreover, the evaporator 10a of this modified example is provided with a vibration mechanism 18 that vibrates the supplying part 1a (source material storage part 5a). With this, the PMDA powder is facilitated to fall down to the heating part 2 from the supplying part 1a (source material storage part 5a), and thus an amount of the PMDA gas generated in the evaporator 10a may be further stabilized. The vibration mechanism 18 may include, for example, a piezoelectric vibration element. In this case, when a vibration frequency is adjusted by adjusting a frequency of a driving voltage of the piezoelectric vibration element, the PMDA powder can be further facilitated to fall down.
Next, a second modified example of the first embodiment according to the present invention is explained with reference to
An evaporator according to this modified example is different from the evaporator 10a according to the first modified example of the first embodiment in that the evaporator of this modified example has a gas passage through which the carrier gas flows in a lower portion of the heating part, and the rest is substantially the same as the evaporator 10a. The following explanation is focused on the differences.
Referring to
A gas passage 17 is provided in a lower portion of the heating part 2b. The gas passage 17 connects the gas introduction part 3b and the gas discharging part 4b in order to be in gaseous communication with each other. With this, the carrier gas C flows through the gas introduction pipe 11, the gas introduction opening 12, the gas passage 17, the gas discharging opening 15, and the gas discharging pipe 16 in this order.
Incidentally, portions corresponding to the gas introduction part 3 (or 3a) and the gas introduction chamber 13 (or 13a) in the first embodiment (or its first modified example) are included in the gas passage 17.
In addition, the evaporator 11b according to this modified example is provided with a heating mechanism 9a that heats the heating part 2b via the gas passage 17 in a lower portion of the heating part 2b, and a heating mechanism 9b that heats the heating part 2b from its side.
Next, effects (or advantages) of the evaporator 10b according to this embodiment are explained with reference to
As shown in a subsection (a) of
When the PMDA powder RM1 held by the heating part 2b is heated up to the PMDA sublimation temperature or more, the PMDA powder RM1 is sublimated and thus the PMDA gas R is generated, as shown in a subsection (b) of
Incidentally, the PMDA powder stored near the boundary between the supplying part 1b (source material storage part 5b) and the heating part 2b is heated at temperatures higher than the sublimation temperature by thermal conduction of the heat H from the heating part 2b, and thus is sublimated. However, the PMDA gas is generated only from the PMDA powder stored near the boundary, and not generated from the entire PMDA powder amount stored in the supplying part 1b (source material storage part 5b).
As the PMDA gas R is being generated in the heating part 2b as described above, the particle size of the PMDA powder RM1 becomes smaller, and thus voids may be produced within the PMDA powder PM1 stored in the heating part 2b, as shown in a subsection (b) of
However, the voids are readily filled because the PMDA powder RM2 stored in the supplying part 1b (source material storage part 5b) falls due to the gravitational force G, as shown in a subsection (c) of
Next, a film deposition apparatus according to a second embodiment of the present invention is explained. The film deposition apparatus according to this embodiment is an apparatus that deposits an insulation film on a wafer surface using the PMDA gas supplied from the evaporator according to the first embodiment of the present invention.
In addition, an ODA evaporator 30 and a PMDA evaporator 10 according to the first embodiment are connected to the injectors 23a and 23b respectively through corresponding valves 32 and 31, and through an introduction part 33. Incidentally, although the evaporator 10 according to the first embodiment is used as the PMDA evaporator in the second embodiment, one of the evaporators 10a and 10b according to the first and the second modified examples of the first embodiment, respectively, may be used.
As shown in
Subsequently, the evaporated PMDA and the ODA are supplied to the corresponding injectors 23a and 23b through the corresponding valves 31 and 32, and thus deposited on the wafers W. At this time, the polymerization reaction of the PMDA and ODA takes place following the next formula (1).
In the foregoing, while preferred embodiments according to the present invention have been described, the present invention is not limited to the specific embodiments, but may be variously modified or altered within the scope of the accompanying Claims.
For example, the vibration mechanism 18 (
Moreover, a small amount of, for example, nitrogen gas, inert gas, or the like may be introduced into the supplying parts 1-1b (source material storage parts 5-5b) from the above-mentioned source material introduction opening 7 or a gas introduction opening provided separately from the source material introduction opening 7. By supplying a small amount of the gas to the supplying parts 1-1b (source material storage parts 5-5b), the PMDA gas R generated in the heating parts 2, 2b is impeded from diffusing from the heating parts 2, 2b toward the supplying parts 1-1b (source material storage parts 5-5b) through the PMDA powder PM. Therefore, the PMDA gas R generated in the heating parts 2, 2b can be stably supplied to the film deposition apparatus from the gas discharging parts 4-4b.
A shape of the heating part 2 is not limited to a parallelepiped, but may be cubic. Even in this case, the heating part 2 may have an upper opening and opposing two side surfaces as the mesh parts 8. In addition, the heating part 2 may have an arbitrary shape, as long as the heating part 2 has an upper opening in order to be in physical communication with the supplying part 1 (source material storage part 5) above the heating part 2 and has the mesh parts 8 that allow the carrier gas C to flow through the heating part 2.
In addition, the mesh part 8c constituting the bottom surface of the heating part 2b in the evaporator 10b according to the second modified example of the first embodiment is not limited to be flat but may be convex downward.
Moreover, a source material transfer pipe may be connected to the source material introduction openings 7, 7a, and the PMDA powder (solid source material) may be introduced into the supplying part 1 (source material storage part 5) through the source material transfer pipe.
The insulation members 6a, 6b may be made of a material having thermal conductivity less than the thermal conductivity of the material of the heating part 2 having a container-like shape. With this, the PMDA powder stored in the supplying part 1 (source material storage part 5) is further impeded from being heated above the sublimation temperature.
In addition, the gas introduction chamber 13, the heating part 2, and the gas discharging chamber 14 may be continuously integrated in the gas introduction part 3, as long as the carrier gas C can be introduced into the heating part 2.
Incidentally, while the boundary between the heating part 2 and the supplying part 1 (or 1a) can be relatively easily defined because the carrier gas flows through the heating part 2 in the evaporator 10 (or 10a) according to the first embodiment (or its first modified example), the boundary between the heating part 2b and the supplying part 1b is not easily defined. However, the heating part 2b that heats and sublimates the PMDA powder and the supplying part 1b that is arranged above the heating part 2b and is capable of supplying the PMDA powder to the heating part 2b are defined.
In addition, the supplying parts 1, 1a, 1b and the heating parts 2, 2b are provided in one container and the PMDA powder is supplied into the heating parts 2, 2b from the supplying parts 1, 1a, 1b due to its own weight. However, the supplying parts 1, 1a, 1b and the heating parts 2, 2b may be configured as separate bodies, as long as the PMDA powder can be supplied to the heating parts 2, 2b from the supplying parts 1, 1a, 1b.
Moreover, while the PMDA powder is sublimated to generate the PMDA gas in the above explanation, other solid source materials can be apparently used in other embodiments.
This international application claims priority based on Japanese Patent Application No. 2009-061587 filed Mar. 13, 2009, the entire content of which is incorporated herein by reference in this international application.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-061587 | Mar 2009 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2010/054118 | 3/11/2010 | WO | 00 | 9/22/2010 |
