HIGH THROUGHPUT POWDER TREATMENT SYSTEMS

Abstract

A system for processing powder includes a process tube connected to load lock chamber via a vacuum valve. The load lock chamber includes first and second stations. Each of the first and second stations is configured to receive a barrel containing powder to be treated. A mechanical transfer mechanism is configured to: move a barrel containing powder to be treated from the first station into the process tube; move a barrel containing powder to be treated from the second station into the process tube; move a barrel containing treated powder from the process tube to the first station; and move a barrel containing treated powder from the process tube to the second station.

Claims

1. A system for processing powder comprising: a process tube connected to load lock chamber via a vacuum valve, the load lock chamber including first and second stations, each of the first and second stations configured to receive a barrel containing powder to be treated; and a mechanical transfer mechanism configured to: move a barrel containing powder to be treated from the first station into the process tube; move a barrel containing powder to be treated from the second station into the process tube; move a barrel containing treated powder from the process tube to the first station; and move a barrel containing treated powder from the process tube to the second station.

2. The system according to claim 1, wherein the process tube includes a stationary thermocouple, a stationary gas injector, and an exhaust port.

3. The system according to claim 1, further comprising a rotary shaft configured to advance a barrel containing powder to be treated from the first station into the process tube and to rotate the barrel once positioned within the process tube.

4. The system according to claim 1, further comprising a heater to maintain the process chamber substantially at treatment temperature at all times during barrel movement.

5. The system according to claim 1, wherein the mechanical transfer mechanism is a linear transfer mechanism.

6. The system according to claim 1, wherein the mechanical transfer mechanism includes a transfer arm configured to receive a barrel.

7. The system according to claim 5, wherein the mechanical transfer mechanism includes an elevator configured to receive the barrel from the transfer arm.

8. The system according to claim 1, wherein the process tube is configured to provide a one or more treatment processes selected from chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma deposition, electrochemical deposition, molecular layer deposition, or atomic layer deposition.

9. A method of powder treatment comprising: loading a first barrel containing a powder for treatment into a load lock chamber; preparing the first barrel for treatment while loaded in the load lock chamber; loading the first barrel into a process tube; treating the powder within the first barrel in the process tube; while treating powder within the first barrel, loading a second barrel containing a powder for treatment into the load lock chamber; preparing the second barrel for treatment while loaded in the load lock chamber; after treating of the powder in the first barrel is complete, transferring the first barrel back to the load lock chamber; while the first barrel containing treated powder is positioned in the load lock chamber, loading the second barrel into the process tube; and treating a powder contained in the second barrel.

10. The method of powder treatment according to claim 9, wherein the first barrel containing a powder for treatment is loaded into a first station of the load lock chamber; and the second barrel containing powder for treatment is loaded into a second station of the load lock chamber.

11. The method of powder treatment according to claim 9, wherein preparing the first barrel for treatment while loaded into the first station includes at least one of pre-heating the first barrel or introducing inert gas into the first barrel.

12. The method of powder treatment according to claim 9, wherein treating the powder within the first barrel in the process tube includes at least one treatment process selected from chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma deposition, electrochemical deposition, molecular layer deposition, or atomic layer deposition.

13. The method of powder treatment according to claim 9, wherein treating the powder within the first barrel in the process tube includes: spinning the first barrel at a speed sufficient to provide a centrifuging condition; slowing rotation of the first barrel to create a cataracting condition within the first barrel; and introducing a process gas to treat powder within the first barrel.

14. The method of powder treatment according to claim 13, further comprising: spinning the first barrel at a speed sufficient to provide a centrifuging condition after treating the powder; and continuing to rotate at a centrifuging speed while transferring the first barrel back to the load lock chamber.

15. The method of powder treatment according to claim 9, further comprising cooling the first barrel containing treated powder while positioned in the load lock chamber.

16. The method of powder treatment according to claim 9, further comprising recovering the treated powder from at least one of the first barrel or the second barrel.

17. The method of powder treatment according to claim 9, further comprising, after treating the powder in the second barrel is complete, transferring the second barrel back to the load lock chamber.

18. The method of powder treatment according to claim 17, further comprising maintaining the process chamber at a substantially constant treatment temperature at all times during loading and transferring the first and second barrels.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present disclosure may be understood by reference to the accompanying drawings, when considered in conjunction with the subsequent, detailed description, in which:

[0031] FIG. 1 schematically shows a process tube suitable for use in systems in accordance with this disclosure;

[0032] FIG. 2 schematically shows an automatic loading mechanism suitable for use in systems in accordance with this disclosure;

[0033] FIG. 3 schematically shows a dual barrel load lock chamber suitable for use in systems in accordance with this disclosure;

[0034] FIG. 4 schematically shows a gas injector line and thermocouple suitable for use in systems in accordance with this disclosure;

[0035] FIG. 5 schematically shows the outlet side of a barrel suitable for use in systems in accordance with this disclosure;

[0036] FIG. 6 is a flow chart showing an illustrative method of powder processing in accordance with this disclosure;

[0037] FIG. 7 shows the loading of barrels into a load lock chamber in an illustrative method of powder processing in accordance with this disclosure;

[0038] FIG. 8 shows the preparing of barrels for treatment in the load lock chamber in an illustrative method of powder processing in accordance with this disclosure;

[0039] FIG. 9 shows the positioning of barrels by a transfer arm for transfer from the load lock chamber and into the process tube in an illustrative method of powder processing in accordance with this disclosure;

[0040] FIG. 10 shows the positioning of barrels onto elevators for movement into position for transfer from the load lock chamber and into the process tube in an illustrative method of powder processing in accordance with this disclosure;

[0041] FIG. 11 shows the positioning of barrels by elevators into position for transfer from the load lock chamber and into the process tube in an illustrative method of powder processing in accordance with this disclosure;

[0042] FIG. 12 shows a barrel partially loaded into the process tube in an illustrative method of powder processing in accordance with this disclosure;

[0043] FIG. 13 shows a barrel fully loaded into the process tube in an illustrative method of powder processing in accordance with this disclosure;

[0044] FIG. 14 illustrates variations of the reactor pressure and barrel angular velocity at various steps of an exemplary process in accordance with this disclosure; and

[0045] FIG. 15 is a flow chart showing an illustrative method of powder processing in accordance with this disclosure.

DETAILED DESCRIPTION

[0046] Embodiments of the presently disclosed powder treatment systems are described in detail with reference to the drawings, in which like reference numerals designate identical or corresponding elements in each of the several views. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail.

[0047] Reference is made in detail to specific embodiments, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation, not limitation. It will be apparent to those skilled in the art that various modifications and variations may be made in the embodiments without departing from the scope or spirit of the disclosure. For instance, features illustrated or described as part of one embodiment may be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims and their equivalents.

[0048] While the following description is directed to the exemplary powder treatment systems shown in the figures, it should be understood that the structures and methods described herein may be used in connection with any powder treatment system, especially systems designed for applying materials (e.g., a coating, a nanotube, etc.) to particles, such as, for example a chemical vapor deposition (CVD) system, a physical vapor deposition (PVD) system, a plasma deposition system, an electrochemical deposition system, a molecular layer deposition system, or an atomic layer deposition system. Other types of powder treatment systems with which the present structures and methods may be used or adapted for use will be readily apparent to one skilled in the art reading this disclosure.

[0049] Directional terms such as top, bottom, and the like are used simply for convenience of description and are not intended to limit the disclosure attached hereto. Also, as used herein, the term on includes being in an open or activated position, whereas the term off includes being in a closed or inactivated position. As used herein, the terms first, second, and third may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components.

[0050] As seen in FIG. 1, systems in accordance with the present disclosure may include a rotatable barrel 100 containing powder positioned within a process chamber, e.g., process tube 200. Process tube 200 is connected to load lock chamber 500 via a gate valve, such as vacuum valve 300. Process tube 200 is also provided with a stationary thermocouple 210, a stationary gas injector 220, and an exhaust port 230. Barrel 100 includes a rotary shaft connection 120.

[0051] Process tube 200 is a vacuum chamber in which the treatment processes (e.g., CVD, sputtering, electron beam evaporation, thermal evaporation, etc.) take place. Load lock chamber 500 is essentially an auxiliary, secondary vacuum chamber attached to process tube 200 with vacuum valve 300 between the chambers. Load lock chamber 500 has its own high vacuum pumping system and venting (not explicitly shown). It contains two (or more) stations each configured for receiving a barrel containing powder to be treated. A mechanical transfer mechanism is provided to move barrels to and from process tube 200. Load lock chamber 500 reduces the cycle time of processing powder and reduces the potential for contamination in process tube 200. Barrels 100 are loaded into the load lock chamber 500 while at atmospheric pressure and temperature, and may contain air. Barrel 100 within load lock chamber 500 may then be preheated, load lock chamber 500 pumped down to a high vacuum pressure, and filled with an inert gas. Vacuum valve 300 is then opened between load lock chamber 500 and the process tube 200. Barrel 100 is then mechanically transferred from load lock chamber 500 to process tube 200 by means of a linear transfer mechanism. After the powder is processed, barrel 100 is transferred back to load lock chamber 500. During this process, the process tube 200 is always under vacuum and maintained at or near treatment temperature. Thus, load lock chamber 500 allows powder to be transferred into the process tube 200 without venting process tube 200 to atmosphere.

[0052] Treatment of powder within barrel 100 occurs within process tube 200. In embodiments, treatment of powder can be achieved as described in the '851 application. As described therein, the system may vary the speed of rotation of barrel 100 (which is essentially a rotary treatment vessel) containing the powder to be treated depending upon the presence or absence of net gas flow through the barrel 100 or process tube 200 at different stages of the treatment process. During treatment stages where gas flow may be present (e.g. pump down), barrel 100 is spun at a centrifugal speed. During treatment stages where net gas flow may be minimal or introduced into barrel 100 in such a way as to avoid or substantially minimize disturbance of the particles, the rotational speed of barrel 100 is at a cataracting speed, which is less than a centrifugal speed. Cataracting (with or without a comb) is the condition under which the uniform processing (heat treatment, surface modification, thin film deposition, etc.) should take place for best results. This is also the condition that is most susceptible to elutriation since the fine powder particles are distributed evenly and falling throughout barrel 100 by design and therefore are easily entrained in any net gas or vapor flow through the reactor. Entrained particles may be elutriated out with the exhaust resulting in yield loss or equipment issues including contamination of valves, clogging of filters, etc. By ensuring that, during treatment stages, any net gas flow may be minimal or introduced into barrel 100 in such a way as to avoid or substantially minimize disturbance of the particles, elutriation losses or equipment issues are avoided or substantially reduced.

[0053] As seen in FIG. 2, automated, sequential loading of barrel 100 into process tube 200 is achieved using load lock chamber 500. Load lock chamber 500 can accommodate two barrels 100a and 100b at first station 550a and second station 500b, respectively, and is thus sometimes referred to herein as a dual load lock chamber. A barrel rotation shaft 240 is provided to engage the rotary shaft connection 120 on barrel 100a to automatically advance barrel 100a into process tube 200, and rotate barrel 100a during the treatment process, for example as described in the '851 application. Rotation of barrel rotation shaft 240 is achieved by motor 260. While barrel 110a is undergoing treatment within process tube 200, barrel 100b is loaded into load lock chamber 500, where it is prepared for treatment by pre-heating and replacing air with a suitable atmosphere for treatment such as, for example, inert gas. A barrel lift mechanism 600 positions barrels 100a, 100b for loading into process tube 200.

[0054] As seen in FIG. 3, barrels 100a, 100b are positioned within dual load lock chamber 500. Advantageously, fresh barrel 100b with powder can be loaded into load lock chamber 500 at room temperature. Load lock chamber 500 can then be evacuated to vacuum (to remove air) and backfilled with inert gas. Load lock chamber 500 can also be preheated prior to loading hot barrel 100b into the process tube. Barrel 100a with treated powder can be unloaded into the load lock chamber 500 without the need to cool down to low temperature within process tube 200, but rather can cool down to room temperature within load lock chamber 500 during treatment of powder within barrel 100b (which is automatically loaded into process tube 200 after removal of barrel 100a from process tube 200). Since treatment time typically exceeds cool down time, while barrel 100b is undergoing treatment, barrel 100a can be removed from load lock chamber 500 and a third barrel (not shown) with powder can be pre-loaded into load lock chamber 500 and prepared for treatment once treatment of the powder within barrel 100b is complete.

[0055] As seen in FIG. 4, the inlet side of barrel 100 receives stationary gas injector line 220, that includes a plurality of holes 225 on the top for injection of gas upward into barrel 100, where particles are more fluidized due to rotation (see the '851 application).

[0056] As seen in FIG. 5, the outlet side of barrel 100 may have gaps 150 in barrel end cap 140 between rotating parts and stationary injector 220 and thermocouple 210. These gaps 150 can be used as the internal exhaust port from the barrel when powder is confined using centrifugal confinement as described in the '851 application.

[0057] In aspects, the present disclosure relates to methods of powder treatment. FIG. 6 shows a flow chart for an illustrative method (700). The methods include loading a first barrel containing powder for treatment into a load lock chamber (710). Once loaded, the first barrel is prepared for treatment (720). Preparation for treatment may include pre-heating and/or introduction of inert gas. Once prepared, the first barrel is loaded into a process tube (730). Treatment of the powder within the process tube is then carried out (740). While treatment on the first tube is underway, the method includes loading a second barrel containing powder for treatment into the load lock chamber (750). Once loaded, the second barrel is prepared for treatment (760). Preparation for treatment may include pre-heating and/or introduction of inert gas. After treatment of the powder in the first barrel is complete, it is transferred back to the load lock chamber for cooling (770). While the first barrel is cooling, the second barrel is loaded into the process tube (780) where treatment of the powder contained in the second barrel is achieved (790). The steps of the method can then be repeated any desired number of times with third, fourth, fifth, etc. barrels. It should, of course, be understood that one or more of the previously described method steps can be achieved automatically by one or more controllers.

[0058] FIGS. 7-13 show a sequence of steps in an example process in accordance with the present disclosure. As seen in FIG. 7, load lock chamber 500 is initially empty of barrels and at atmospheric pressure. Hinged doors (not shown) of load lock chamber 500 are opened and one or more barrels 100a, 100b are slid/rolled into load lock chamber 500 directly onto transfer arms 550a, 550b.

[0059] Referring to FIG. 8, barrels 100a, 100b are positioned in transfer arms 550a, 550b and the hinged doors (not shown) are closed to seal load lock chamber 500 which can then be evacuated. End cap 275 of process tube 200 is positioned within load lock chamber 500 when barrel rotation shaft 240 and rotation motor 260 are fully retracted (all the way towards left in FIG. 8).

[0060] In FIG. 9, transfer arm 550a swings barrel 100a to the center plane of load lock chamber 500 (arrow A), directly over receiving fixtures 560 mounted to end cap 275.

[0061] As seen in FIG. 10, elevators 610 come up to receive barrel 100a from transfer arm 550a. Transfer arm 550a retracts toward the side of load lock chamber 500, so that barrel 110a (now supported on elevators 610) is free to move into position for loading into process tube 200.

[0062] In FIG. 11, elevator 610 lowers barrel 100a into receiving fixtures 560. Elevators 610 lower further below receiving fixtures 560 to allow barrel 100a and receiving fixtures 560 to move laterally into process tube 200 (to the right in FIG. 11).

[0063] FIG. 12 shows end cap 275 with receiving fixtures 560 and barrel 100a partially loaded (arrow B) into process tube 200.

[0064] As seen in FIG. 13, end cap 275 passes through vacuum valve 300 and seals to a flange of process tube 200 (now shown transparent). Barrel rotation motor 260 never enters load lock chamber 500. There is a linear seal for barrel rotation shaft 240 as it passes through the end of load lock chamber 500. The process tube 200 is evacuated and other steps are taken to prepare it for processing of the powder.

[0065] When processing of the powder is complete, end cap 275 moves back through and to the far side of load lock chamber 500 (left in the Figures), elevators 610 and load arms 550a, 550b shuffle around, removing processed barrel 100a away from the center line of process tube 200 and loading the next barrel 100b onto receiving fixtures 560. Loading and processing sequences are then repeated.

[0066] While this second barrel 100b is in process, the first barrel 100a is cooling. The load lock chamber 500 (which has been under vacuum since after the hinged barrel doors closed) can be brought back to atmospheric pressure, hinged door (not shown) opened, first barrel 100a removed, and a third barrel (not shown) introduced into load lock chamber 500 in the location from which barrel 100a was removed.

[0067] Any variety of treatment processes may be employed to treat powder within the barrel once it is loaded into the process chamber. These various processes may involve treatment sequences during which treatment temperature, pressure, and the flow of process gas (or gases) can be varied over time. Many such process variations are within the purview of those skilled in the art. FIG. 14 shows the variations of the reactor pressure and angular velocity when an exemplary treatment process in accordance with the present disclosure is performed.

[0068] FIG. 15 shows a flow chart for another illustrative method (900) in accordance with the present disclosure that can be used to carry out a process employing the pressures and velocities of FIG. 14. The method includes at step 910 loading a first barrel containing powder for treatment from the load lock chamber to the process chamber at constant pressure with the end cap sealed, no gas flow, no pumping, and no rotation of the barrel. At step 915, the barrel begins to spin, going from zero spin to a spinning at a speed sufficient to provide a centrifuging condition. A vacuum valve is closed, and the process tube and barrel are pumped down at step 920. With the vacuum valve still closed, a leak back check is performed (step 925), and then, at step 930, the process tube and barrel are backfilled with inert gas. At step 935, the flow of gas is shut off, the vacuum valve is opened, and the process tube and barrel are pumped down. It should be understood that steps 930 and 935 may be repeated as many times as necessary to pump-purge the process tube and barrel. It also should be understood that if the load lock chamber has been pump-purged sufficiently prior to loading the barrel into the reactor, steps 930 and 935 may not be necessary.

[0069] At step 940, the vacuum valve is closed, and the rotation of the barrel is slowed down to create a cataracting condition within the barrel. Once a cataracting condition is achieved, process gas is turned on and the process tube and barrel are backfilled to a target pressure for treatment (945). At step 950, with the flow of process gas turned off, treatment continues until the depletion of precursor is achieved. Once the precursor is depleted, at step 955, the rotation speed of the barrel is increased to achieve a centrifuging condition. The vacuum valve is opened, and the process tube and barrel are pumped down at step 960. It should be understood that steps 940 through 960 may be repeated as many times as necessary to complete the powder processing.

[0070] At step 965, the vacuum valve is closed, and the process tube and barrel are backfilled with inert gas. The flow of gas is turned off, the vacuum valve is opened, and the process tube and barrel are pumped down at step 970. It should be understood that steps 965 and 970 may be repeated as many times as necessary to pump-purge the process tube and barrel.

[0071] At step 975, the vacuum valve is closed, and inert gas is backfilled to offload pressure within the process tube and barrel. The rate of rotation of the barrel is then reduced from a centrifuging speed to zero at step 980. The barrel is unloaded from the process chamber and moved to the load lock chamber at step 990, at which time the hinged door to the load lock chamber can be opened. Care should be taken to minimize pressure differential between the load lock chamber and process chamber when the hinged door opens. Alternatively, the barrel may continue to rotate at a centrifuging speed during unload from the process chamber to the load lock chamber.

[0072] This written description uses examples to describe the present powder treatment system and processes to enable any person skilled in the art to make and use any devices or systems and perform any incorporated methods. The scope of the disclosure may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of this disclosure if they include structural elements that do not differ from the explicitly disclosed embodiments, or if they include equivalent structural elements with insubstantial differences from the explicitly disclosed embodiments.

[0073] It should be understood that various aspects disclosed herein may be combined in different combinations than the combinations specifically presented in the description and accompanying drawings. It should also be understood that, depending on the example, certain acts or events of any of the processes or methods described herein may be performed in a different sequence, may be added, merged, or left out altogether (e.g., all described acts or events may not be necessary to carry out the techniques). In addition, while certain aspects of this disclosure are described as being performed by a single module or unit for purposes of clarity, it should be understood that the techniques of this disclosure may be performed by a combination of units or modules associated with a particle treatment system.