Preprocessing method for solid material, and solid material product filled with solid material manufactured using said solid material preprocessing method

Abstract

A preprocessing method comprises a sintering step of heating a solid material container filled with a solid material using a temperature which is lower than either the melting point or sublimation of the solid material, whichever is lower, and crystallizing at least part of the solid material, and an impurity removal step of heating the solid material container filled with the solid material using a temperature which is lower than either the melting point or sublimation of the solid material, whichever is lower, and removing at least part of the impurities included in the solid material.

Claims

1. A method for preprocessing a solid material, the method comprising an impurity removal step of: heating a solid material which fills a solid material container at a temperature lower than the melting point of the solid material, removing at least part of the impurities contained in the solid material, heating the solid material which fills a solid material container at a temperature less than a phase transition point of the solid material, and sintering at least part or all of the solid material, wherein in the impurity removal step, a carrier gas having a predetermined flow rate is introduced into the solid material container, and in the sintering step no carrier gas is introduced into the solid material container, wherein the solid material container has a carrier gas introduction pipe which introduces the carrier gas into the solid material container, a first filling unit which is disposed inside the solid material container and is filled with the solid material, a second filling unit which is disposed on at least part of an outer circumference of the first filling unit and is filled with the solid material, at least one tray-shaped third filling unit which is disposed on a ceiling-side of the interior of the solid material container, a solid material discharge pipe which discharges the carrier gas with the accompanying solid material from the solid material container, and a heating unit which heats the solid material container, a carrier gas outlet of the carrier gas introduction pipe is provided to the first filling unit, an inlet of the solid material discharge pipe is provided to the third filling unit, and the carrier gas passes through the first filling unit, the second filling unit, and the third filling unit, in this order.

2. The method of claim 1, wherein the impurity removal step is a step of heating the solid material so as to reach a temperature less than a phase transition point thereof.

3. The method of claim 1, wherein the solid material includes a compound selected from the group consisting of WCl.sub.5, WCl.sub.6, WOCl.sub.4, WO.sub.2Cl.sub.2, SiI.sub.4, TiI.sub.4, GeI.sub.4, GeI.sub.2, TiBr.sub.4, Si.sub.2I.sub.6, BI.sub.3, PI.sub.3, TiF.sub.4, TaF.sub.5, MoO.sub.2Cl.sub.2, MoOCl.sub.4, ZrCl.sub.4, NbCl.sub.5, NbOCl.sub.3, TaCl.sub.5, VCl.sub.5, Y(CH.sub.3C.sub.5H.sub.4).sub.3, Sc(CH.sub.3C.sub.5H.sub.4).sub.3, MoCl.sub.5, AlCl.sub.3, HfCl.sub.4, (CH.sub.3).sub.3In, (C.sub.5H.sub.5).sub.2Mg, NbF.sub.5, XeF.sub.2, VF.sub.5, and carboxylic acid anhydride.

4. The method of claim 3, wherein a solid material product is filled in the solid material container.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For a further understanding of the nature and objects for the present invention, reference should be made to the following detailed description, taken in conjunction with the accompanying drawings, in which like elements are given the same or analogous reference numbers and wherein:

(2) FIG. 1 is a view showing an example of a configuration of a solid material container.

(3) FIG. 2 is a view showing the results of the TCD measurement of the gas discharged from the solid material container.

(4) FIG. 3 is a view showing change over time in the vapour pressure of the solid material.

(5) FIG. 4 is a view showing an example of a configuration of a solid material container.

(6) FIG. 5 is a view showing a standard sample measurement results using an XRD device.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(7) Several embodiments of the present invention are described below. The embodiments described below describe one example of the present invention. The present invention is not limited in any way to the following embodiments, and includes variations implemented without departing from the scope of the present invention. Note that all the configurations described below are not necessarily essential configurations of the present invention.

Embodiment 1—Impurity Removal Step and Sintering Step

(8) A method for preprocessing a solid material according to the present invention comprises an impurity removal step of heating a solid material which fills a solid material container at a temperature lower than the melting point of the solid material, and removing at least part of the impurities contained in the solid material.

(9) The preprocessing method according to the present invention can further comprise a sintering step of heating the solid material which fills a solid material container at a temperature less than a phase transition point of the solid material, and sintering at least part or all of the solid material.

(10) The solid material may be a precursor used in depositing a semiconductor layer. The solid material may be the precursor itself, or the solid material carried on a carrier body such as beads, etc. The solid material may be in a solid state when being filled into a container, it may be a solid material when the solid material container is being transported, and it may be in a liquid state when being filled or when being heated after being filled. There is no particular limitation on the solid material, which may be a material including a compound selected from the group consisting of an organic compound, an organic metal compound, a metal halide, and mixtures of these.

(11) Table 1 gives the melting points and phase transition points for the main solid materials.

(12) The heating temperature in the impurity removal step need only be a temperature lower than the melting point of the solid material, e.g., any temperature in the range 25° C. to 283° C., inclusive, for WCl.sub.6, which has a melting point of 284° C., or any temperature in the range 25° C. to 249° C., inclusive, for tungsten pentachloride (henceforth WCl.sub.5), which has a melting point of 250° C.

(13) Similarly, the temperature for other solid materials need only be at least 25° C. and within a range no greater than the melting point of the solid material. The upper limit of the heating temperature may be, for example, a temperature 1° C. lower than the melting points given in Table 1 for the solid materials given in Table 1.

(14) TABLE-US-00001 TABLE 1 Melting point Phase transition point Compound (° C.) (° C.) ZrCl.sub.4 437 — Y(CH.sub.3C.sub.5H.sub.4).sub.3 124 — XeF.sub.2 129 — WOCl.sub.4 211 — WO.sub.2Cl.sub.2 265 — WCl.sub.6 284 176 WCl.sub.5 250 180 VF.sub.5 20 — VCl.sub.5 260 — TiI.sub.4 150 106 TiF.sub.4 344 — TiBr.sub.4 39 — TaF.sub.5 97 — TaCl.sub.5 216 — SiI.sub.4 120 — Si.sub.2I.sub.6 200(decompose) — Sc(CH.sub.3C.sub.5H.sub.4).sub.3 104 — PI.sub.3 61 — NbF.sub.5 77 — NbCl.sub.5 205 — MoOCl.sub.4 100 — MoO.sub.2Cl.sub.2 184(Subl) — MoCl.sub.5 194 — HfCl.sub.4 432 — GeI.sub.4 146 — GeI.sub.2 460 — BI.sub.3 44 — AlCl.sub.3 192 — (CH.sub.3).sub.3In 88 — (C.sub.5H.sub.5).sub.2Mg 176 —

(15) The heating time in the impurity removal step depends on the size of the solid material container, the volume of the solid material container, and the weight of the solid material when filling the solid material container. The heating time may be 2 to 12 hours, inclusive, when the solid material container is, for example, round and has a diameter of 0.3 m to 1.0 m and a height of 0.3 to 1.0 m, and the filling weight of the solid material is 1 kg to 20 kg.

(16) The heating time during the impurity removal step may be determined on the basis of the target weight of the solid material in the solid material container. For example, the heating time in the impurity removal step may be the amount of time until the weight of the solid material in the solid material container falls by 10% compared to when the impurity removal step started.

(17) The impurity removal step may further include the sintering step. The sintering step can be carried out after the impurity removal step is carried out, or concurrently with the impurity removal step.

(18) The heating time in the sintering step depends on the size of the solid material container, the volume of the solid material container, and the weight of the solid material when filling the solid material container. The heating time may be 8 to 24 hours, inclusive, when the solid material container is, for example, round and has a diameter of 0.3 m to 1.0 m and a height of 0.3 to 1.0 m, and the filling weight of the solid material is 1 kg to 20 kg.

(19) The heating temperature during the impurity removal step and the sintering step is more preferably a temperature lower than the phase transition point of the solid material. If it is a temperature less than the phase transition point, the phase transition speed is faster the higher the temperature, which is even more preferable. For example, in the case of WCl.sub.6, which has a phase transition point of 176° C., the temperature range of 126° C. to 175° C., inclusive, is preferable, and from 166° C. to 175°, inclusive, is more preferable. In the case of WCl.sub.5 which has a phase transition point of 180° C., the temperature range of 130° C. to 179° C., inclusive, is preferable, and from 170° C. to 179°, inclusive, is more preferable.

(20) In the case of TiI.sub.4 which has a phase transition point of 106° C., the temperature range of 56° C. to 105° C., inclusive, is preferable, and from 96° C. to 105°, inclusive, is more preferable.

(21) The solid material container is not particularly limited to the container filled with the solid material, and may be a metal container made out of aluminium, etc., or a specific metal container made out of glass, etc. It is possible for the solid material container to have a carrier gas inlet and inlet valve, a discharge outlet and discharge valve for discharging the carrier gas and the solid material vapour accompanying the carrier gas, and a charging port and charging valve for filling the solid material and a maintenance valve as needed. The interior of the solid material container may be an integrated container with one space, or it may be divided into two or more spaces by trays or gate valves, etc.

(22) The interior of the solid material container may be depressurized before carrying out the impurity removal step. The pressure inside the solid material container during depressurization is not limited to any particular pressure as long as it does not go beyond the withstand pressure of the solid material container during heating, and can be set to, for example, any pressure between 10 Torr and atmospheric pressure.

(23) The impurity removal step may be from one hour to 50 hours long, depending on the state of the solid material, the volume of the solid material container, and the filled amount of the solid material, etc. The heating temperature is less than the melting point of the solid material. The heating temperature is less than the melting temperature of the solid material and may be a temperature at or below the phase transition point.

(24) The sintering step may be from 0.5 hours to 50 hours long, depending on the state of the solid material, the volume of the solid material container, the state and content of the impurities included in the solid material, and the filled amount of the solid material, etc. The heating temperature is less than the melting point of the solid material. The heating temperature is less than the melting temperature of the solid material and may be a temperature at or below the phase transition point.

Separate Embodiment 1

(25) As another embodiment, it is also possible to introduce the carrier gas when initiating the heating, without carrying out the sintering step of heating a solid material container 1 without introducing the carrier gas. The temperature of the solid material container 1 may be 170° C., as in Embodiment 1, the carrier gas flow rate may be 10 SCCM, and the heating time may be 20 hours.

Separate Embodiment 2

(26) As yet another embodiment, it is also possible for the temperature of the solid material container 1 to be 160° C., the carrier gas flow rate to be 10 SCCM, and the heating time to be 50 hours in the preprocessing method as in Embodiment 1.

Separate Embodiment 3

(27) As yet another embodiment, it is also possible to carry out an impurity removal step in which the temperature of the solid material container 1 is 170° C., the carrier gas flow rate is 10 SCCM, and the heating time is 2 hours in the preprocessing method as in Embodiment 1, and then stop introduction of the carrier gas, and carry out the sintering step, with the temperature of the solid material container 1 maintained at 170° C. for 12 hours.

(28) The carrier gas is not limited to any particular gas, and may be nitrogen, argon, helium, dry air, or hydrogen, or a combination thereof. An inert gas which does not cause a chemical reaction with the solid material is selected.

Separate Embodiment 1—Container Structure

(29) The solid material container 1 according to Embodiment 1 is described below, with reference to FIG. 1. The solid material container 1 is a solid material container for gasifying and supplying solid materials S1, S2, and S3, having a carrier gas introduction pipe 11 which introduces the carrier gas into the solid material container 1, a first filling unit 21 which is disposed inside the solid material container 1 and is filled with the solid material S1, a second filling unit 22 which located on at least part of the outer circumference of the first filling unit 21 and is filled with the solid material S2, at least one tray-shaped third filling unit 23 which is disposed on the ceiling side of the interior of the solid material container 1, and a solid material discharge pipe 12 which discharges the solid materials S1, S2, and S3 accompanying the carrier gas out of the solid material container.

(30) A carrier gas outlet port 13 in the carrier gas introduction pipe 11 is provided to the first filling unit 21. An inlet port 14 of the solid material discharge pipe 12 is provided to the third filling unit 23.

(31) The solid material container is configured such that the carrier gas passes through the first filling unit 21, the second filling unit 22, and the third filling unit 23 in this order. Details are described below.

(32) The solid material container 1 is completely made out of stainless steel and is configured by securing a stainless steel lid 42 to a stainless steel round cylindrical container 41 which is closed at one end with screw fittings 43. A top edge 44 of the round cylindrical container 41 is thicker than parts other than the top edge, because the screw fittings 43 are inserted thereinto and in order to secure the bottom of the round cylindrical solid material container 41 and the lid 42, which are heavy, together with sufficient strength. Besides the carrier gas introduction pipe 11 and the solid material discharge pipe 12, the lid 42 is provided with a maintenance port (not shown in the drawings) and a pressure gauge port (not shown in the drawings). The carrier gas introduction pipe 11 is provided with a container inlet valve 111, and the solid material discharge pipe is provided with a container outlet valve 121.

(33) The tray 31 which forms the third filling unit 23 is a flat, round tray made out of stainless steel, and is designed such that the outer circumference of the tray is in contact with the inside of the top edge 44. The places where the top edge 44 comes in contact with the tray 31 transfers heat to the third filling unit 23 when the solid material container 1 is heated from the outside. The side walls of the tray 31 are in circular contact with the lid 42. Gas is thus prevented from flowing directly into the solid material discharge pipe 12 from the second filling unit 22.

(34) Dividers 32 which divide the first filling unit 21 and the second filling unit 22 are cylindrical stainless steel plates. Circular grooves 41a having the a radius equal to the diameter of the cylinders of the dividers 32 are formed in the bottom face of the round cylindrical container 41, and bottom edges of the dividers 32 fit into the grooves 41a.

(35) The tray 31 is disposed on the top edges of the dividers 32. Eight 2-mm-diameter holes (corresponding to carrier gas through-section 33) are formed horizontally at equal distances in the bottom of the dividers 32 (at a height of 5 mm from the bottom face of the solid material container).

(36) The carrier gas introduction pipe 11 passes through the middle of the tray 31 forming the third filling unit 23, and the carrier gas outlet 13 opens into the first filling unit 21. The carrier gas is introduced into the first filling unit 21 from the carrier gas introduction pipe 11 and comes in contact with the solid material S1 filling the first filling unit 21. A through-section (not shown in the drawings) is provided to the tray 31. The carrier gas introduction pipe 11 passes through the through-section in the tray 31. The through-section in the tray 31 is secured to the part of the carrier gas introduction pipe 11 which passes therethrough by means of packing. The packing not only prevents solid material from falling form the third filling unit 23 into the first filling unit 21, but also prevents the gas in the first filling unit 21 from flowing directly into the third filling unit 23 without passing through the second filling unit 22.

(37) The solid material S1 in the first filling unit 21 is gasified (or sublimated) and flows into the second filling unit 22 through a carrier gas through-section 33 accompanied by the carrier gas. The carrier gas and solid material vapour flowing into the second filling unit 22 come in contact with the solid material S2 filling the second filling unit 22. The second filling unit 22 has a pressure around 1 Torr lower than the first filling unit 21, and the surface of the solid material S1 filling the first filling unit 21 is about 1° C. hotter than the surface of the solid material S2 filling the second filling unit 22. Therefore, the solid material S2 which fills the second filling unit 22 is gasified (sublimated) and flows into the third filling unit 23 via openings 51 (see FIG. 4) in a side wall in the tray 31, accompanied by the carrier gas. The openings 51 are provided in the tray side wall below where it comes in contact with the bottom of the round cylindrical container 41. The openings 51 are 16 2-mm-diameter holes arranged horizontally equidistant along the side face of the tray 31. The pressure in third filling unit 23 is around 1 Torr lower than in the second filling unit 22. Therefore, the solid material S3 filling the third filling unit 23 is gasified and discharged out of the solid material container 1 via the solid material discharge pipe 12, accompanied by the carrier gas.

(38) The carrier gas introduction pipe 11 passes through the middle of the tray 31 forming the third filling unit 23, and the carrier gas outlet 13 opens into the first filling unit 21. The carrier gas is introduced into the first filling unit 21 from the carrier gas introduction pipe 11 and comes in contact with the solid material S1 filling the first filling unit 21. A through-section (not shown in the drawings) is provided to the tray 31. The carrier gas introduction pipe 11 passes through the through-section in the tray 31. The through-section in the tray 31 is secured to the part of the carrier gas introduction pipe 11 which passes therethrough by means of packing. The packing not only prevents solid material from falling form the third filling unit 23 into the first filling unit 21 but also prevents the gas in the first filling unit 21 from flowing directly into the third filling unit 23 without passing through the second filling unit 22.

(39) The solid material S1 in the first filling unit 21 is gasified (or sublimated) and flows into the second filling unit 22 through a carrier gas through-section 33 accompanied by the carrier gas. The carrier gas and solid material vapour flowing into the second filling unit 22 come in contact with the solid material S2 filling the second filling unit 22. The second filling unit 22 has a pressure around 1 Torr lower than the first filling unit 21, and the surface of the solid material S1 filling the first filling unit 21 is about 1° C. hotter than the surface of the solid material S2 filling the second filling unit 22. Therefore, the solid material S2 which fills the second filling unit 22 is gasified (sublimated) and flows into the third filling unit 23 via an opening 51 (see FIG. 4) in a side wall in the tray 31, accompanied by the carrier gas. The opening 51 is provided in the tray side wall below where it comes in contact with the bottom of the round cylindrical container 41. The openings 51 are 16 2-mm-diameter holes arranged horizontally equidistant along the side face of the tray 31. The pressure in third filling unit 23 is around 1 Torr lower than in the second filling unit 22. Therefore, the solid material S3 filling the third filling unit 23 is gasified and discharged out of the solid material container 1 via the solid material discharge pipe 12, accompanied by the carrier gas.

(40) There is no particular limitation on the heating unit (not shown in the drawings) which heats the solid material container, as long as it can heat the solid material container. It can be a constant-temperature tank which contains all the solid material containers, a mantle heater, or a block heater.

Separate Embodiment 3

(41) One example of an embodiment according to the present invention is a solid material product, in which the solid material container 1 is filled with the solid material WCl.sub.6 which has been preprocessed as shown in Embodiment 1. The solid material product is disposed in a semiconductor device which deposits a semiconductor layer, and the solid material vapour is supplied to the semiconductor device from the solid material container 1. By making the temperature at which the semiconductor layer is deposited around the same as the heating temperature of the preprocessing in Embodiment 1, the semiconductor layer can be deposited while maintaining the crystal state formed during the preprocessing (i.e., while maintaining a fixed vapour pressure). Accordingly, it is possible to deposit a uniform semiconductor layer with a stable amount of the solid material supplied to the semiconductor device.

Separate Embodiment 4

(42) As another embodiment, a semiconductor product can be configured by transferring the solid material to which the preprocessing method as shown in Embodiment 1 from the solid material container 1 used in the preprocessing method into a separate solid material container.

Embodiment 1—Filling the Solid Material

(43) The round cylindrical container 41, the lid 42, the dividers 32, and the tray 31, which have been washed and dried, are placed together with the solid material into a glove box having an inert atmosphere. The dividers 32 are fitted into the round grooves 41a which are on the bottom surface of the round cylindrical container 41 and fixed in place. Of the total quantity of the WCl.sub.6 filling the solid material container 1, part is put in the first filling unit (e.g., around 10% to 70% of the total quantity), and another part is put into the second filling unit (e.g., 10% to 50% of the total quantity). Next, the tray 31 is placed on the dividers 32 and filled with the remaining solid material. Thereafter, the lid 42 is placed on the round cylindrical container 41 and affixed by the screw fittings 43. Packing maintaining a seal is inserted between the round cylindrical container 41 and the lid 42. Filling the solid material container 1 with the solid material is thus complete.

Embodiment 1

(44) The preprocessing method according to Embodiment 1 was carried out using the solid material container shown in FIG. 1.

(45) Filling of Solid Material WCl.sub.6

(46) The round cylindrical container 41, the lid 42, the dividers 32, and the tray 31, which have been washed and dried, were placed together with the WCl.sub.6, which is the solid material, into a glove box having an inert atmosphere. The dividers 32 were fitted into the round grooves 41a which are on the bottom surface of the round cylindrical container 41 and fixed in place. Of the total quantity (6.5 kg) of the WCl.sub.6 filling the solid material container 1, 2.6 kg was put in the first filling unit and another 2.6 kg was put in the second filling unit. Next, the tray 31 was placed on the dividers 32 and filled with the remaining 1.3 kg of the WCl.sub.6. Thereafter, the lid 42 was placed on the round cylindrical container 41 and affixed by the screw fittings 43. Packing maintaining a seal was inserted between the round cylindrical container 41 and the lid 42. Filling the solid material container 1 with the solid material is thus complete.

(47) Preprocessing of the Solid Material

(48) The solid material container 1, filled with the solid material (the WCl.sub.6 in the present embodiment) was depressurized using a vacuum pump.

(49) The pressure inside the solid material container 1 during depressurizing was 100 Torr. Specifically, the container inlet valve 111 was closed, the vacuum pump was connected behind the container outlet valve 121, and the container outlet valve 121 was opened for depressurization.

(50) Next, heating was applied with a mantle heater (not shown in the drawings) disposed outside the solid material container 1 until the temperature of the solid material container 1 reached 170° C. Because the phase transition point of the WCl.sub.6 is 176° C., the WCl.sub.6 constitutes a low-temperature phase in the present embodiment which was heated to 170° C.

(51) After the pressure inside the solid material container 1 reached 100 Torr, the container outlet valve 121 was closed. Next, the carrier gas (nitrogen gas in the present embodiment) was introduced by opening the container inlet valve 111 and the container outlet valve 121 (impurity removal step). The flow rate of the carrier gas was set at 1000 SCCM. The flow time of the carrier gas was 2 hours, and the temperature of the solid material container 1 was maintained at 170° C.

(52) Next, introduction of the carrier gas (nitrogen gas in the present embodiment) was stopped by closing the container inlet valve 111 and the container outlet valve 121 (sintering step). The temperature of the solid material container 1 was maintained at 170° C. for 12 hours.

(53) FIG. 2 shows the results of an analysis carried out using a Shimadzu TCD sensor on the gas discharged from the solid material container 1 with the carrier gas in the impurity removal step. The output value of the TCD sensor was large immediately after the start of the impurity removal step but gradually fell thereafter, and substantially stabilized at around 0.5 hours after the start of the impurity removal step. These result show that the impurities, such as WOCl.sub.4, which have a higher vapour pressure than the WCl.sub.6, were discharged from the solid material container 1. WOCl.sub.4 is an impurity which is mainly produced by oxidation of the WCl.sub.6, and is formed so as to cover the surface of the granulate solid material, thereby minimizing self-diffusion of the WCl.sub.6 inside the solid material. It is thought that the crystal state of the WCl.sub.6 is made uniform by the WOCl.sub.4, which is the impurity formed on the solid surfaces, being removed and the self-diffusion of the granulate WCl.sub.6 being minimized. It is thought that the TCD sensor output value stabilized by removing the WOCl.sub.4, after which there is no longer a need for the impurity to be accompanied by the carrier gas, so the carrier gas supply can be stopped.

(54) Table 2 gives the results of the analysis of the metal impurities included in the WCl.sub.6 after carrying out the preprocessing method according to Embodiment 1. Because the Mo and Zn content of the metal impurities was reduced, we were able to confirm that the metal impurities were removed by the preprocessing method according to Embodiment 1.

(55) TABLE-US-00002 TABLE 2 Prior to After Lower Metal preprocessing preprocessing detection value element (wt. ppm) (wt. ppm) (wt. ppm) Li <0.5 <0.5 0.5 B <10 <10 10 Ba <0.5 <0.5 0.5 Co <0.5 <0.5 0.5 Cr <5 <5 5 Ga <0.5 <0.5 0.5 Mo 1.5 <0.5 0.5 Mg <1 <1 1 Mn <3 <3 3 Zn 1.1 0.7 0.5
Vapour Pressure Measurement of the Solid Material

(56) FIG. 3 gives the results of measuring the vapour pressure of the WCl.sub.6 prior to the preprocessing used in Embodiment 1, using a thermogravimetric analyzer (Mettler Toledo TGA/DSC 3+) at 170° C. The vapour pressure of the WCl.sub.6 tended to drop gradually from 4.6 Torr to 3.4 Torr over time.

(57) On the other hand, when the vapour pressure was measured using the thermogravimetric analyzer at 170° C. for the WCl.sub.6 after the preprocessing in Embodiment 1, the vapour pressure stabilized at 3.3 Torr. These results appear to indicate that the preprocessing according to the present embodiment resulted in formation of a uniform crystal state for the WCl.sub.6 and stabilization of the vapour pressure.

(58) Crystal State Analysis of the Solid Material

(59) XRD (SmartLab by Rigaku) was used to analyze the crystal structure of the WCl.sub.6 prior to the preprocessing according to Embodiment 1. The sample (un-preprocessed WCl.sub.6) was mixed with fluid paraffin and pulverized with an agate mortar. The pulverized sample was placed on a sample plate and measured using a Cu Kα beam in the range 5-80°.

(60) The XRD device has a built-in standard sample measurement value for the crystal states of the low-temperature phases and high-temperature phases of WCl.sub.6 (see FIG. 5), and the content ratio of the low-temperature phase and high-temperature phase in the sample being measured is calculated on the basis of that data. The top half of FIG. 5 gives the low-temperature-phase standard sample measurement results, and the bottom half of FIG. 5 gives the high-temperature-phase standard sample measurement results.

(61) As a result of using XRD to analyze the WCl.sub.6 prior to preprocessing using this procedure, the high-temperature phase occupied 99.9% or more. As a result of using XRD to analyze the WCl.sub.6 after preprocessing using the same procedure, the low-temperature phase occupied 98% or more.

(62) Therefore, in the vapour pressure measurement at 170° C. shown in FIG. 2, it is thought that the WOCl.sub.4 which is an oxide impurity gasified prior to the start of the measurement, and thereafter the crystal state of the WCl.sub.6 changed gradually to the low-temperature phase over time, the vapour pressure dropping at the same time as well. On the other hand, the WCl.sub.6 after preprocessing was in the low-temperature phase, and it is thought that the low-temperature phase state was maintained and the vapour pressure stabilized by maintaining the temperature at 170° C.

Embodiment 2

(63) A stainless steel solid material container 100 shown in FIG. 4 was filled with the solid material WCl.sub.5. The solid material container 100 in FIG. 4 is an integral hollow container with no internal divisions, and has a dip tube type carrier gas introduction pipe 11 and solid material discharge pipe 12.

(64) Without introducing the carrier gas, the pressure inside the solid material container 1 was made 150 Torr, and this was heated for 5 hours at 150° C., which is lower than the melting point of the WCl.sub.5. The melting point of WCl.sub.5 is around 250° C., and the phase transition point from the alpha type to the beta type is 180° C.

(65) Table 3 gives the results of measuring the vapour pressure of the WCl.sub.5 before and after the preprocessing shown in Embodiment 4, using a thermogravimetric analyzer (Mettler Toledo TGA/DSC 3+) at 150° C. The vapour pressure of the WCl.sub.5 which had not been preprocessed tended to drop over time, but the WCl.sub.5 which had been preprocessed, indicated in Embodiment 2, was confirmed to have very stable vapour pressure. It is thought that impurities with higher vapour pressure than the WCl.sub.5 were removed by the preprocessing, and at the same time the crystal state of the WCl.sub.5 mainly formed the alpha type which is the low-temperature phase.

(66) TABLE-US-00003 TABLE 3 Elapsed time WCl.sub.5 vapour pressure prior WCl.sub.5 vapour pressure after (min) to preprocessing (Torr) preprocessing (Torr) 10 5 1.7 20 4.2 1.7 30 3.8 1.6 40 3.3 1.7 50 3 1.6 60 2.8 1.6 70 2.6 1.6 80 2.5 1.5 90 2.5 1.6 100 2.4 1.6 110 2.3 1.6 120 2.2 1.5

(67) Table 4 gives the results of measuring the vapour pressure of the WCl.sub.5 before and after the preprocessing shown in Embodiment 2, using a thermogravimetric analyzer (Mettler Toledo TGA/DSC 3+) at 115° C. The vapour pressure of the WCl.sub.5 which had not been preprocessed tended to drop over time, but the WCl.sub.5 which had been preprocessed, indicated in Embodiment 2, was confirmed to have very stable vapour pressure. It is thought that impurities with higher vapour pressure than the WCl.sub.5 were removed by the preprocessing, and at the same time the crystal state of the WCl.sub.5 mainly formed the alpha type which is the low-temperature phase.

(68) TABLE-US-00004 TABLE 4 Elapsed time WCl.sub.5 vapour pressure prior WCl.sub.5 vapour pressure after (min) to preprocessing (Torr) preprocessing (Torr) 10 0.7 0.1 20 0.5 0.1 30 0.3 0.1 40 0.3 0.1 50 0.3 0.1 60 0.3 0.1 70 0.3 0.1 80 0.3 0.1 90 0.3 0.1 100 0.3 0.1 110 0.3 0.1 120 0.3 0.1

EXPLANATION OF THE REFERENCE NUMERALS

(69) 1 Solid material container 11 Carrier gas introduction pipe 12 Solid material discharge pipe 13 Carrier gas outlet 14 Solid material discharge pipe inlet 21 First filling unit 22 Second filling unit 23 Third filling unit 31 Tray 32 Dividers 33 Carrier gas through-section S1 Solid material (in first filling unit) S2 Solid material (in second filling unit) S3 Solid material (in third filling unit)

(70) It will be understood that many additional changes in the details, materials, steps and arrangement of parts, which have been herein described in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. Thus, the present invention is not intended to be limited to the specific embodiments in the examples given above.