Patent Description:
In the production of silicon crystals grown by the continuous Czochralski method, polycrystalline silicon is melted within a crucible of a crystal pulling device to form a silicon melt. A seed crystal is then lowered to the melt and slowly raised back up. As the seed crystal is continuously grown from the melt, solid polysilicon such as granular polysilicon is added to the melt to replenish the melt. The feed rate of the additional solid polysilicon added to the melt is typically controlled to maintain process parameters. In the production of silicon crystals grown by the batch Czochralski method, solid polysilicon, such as chunk polysilicon, is not added to the melt while the seed crystal is grown but is added between sequential growing processes. The feed rate of the additional polysilicon is controlled to maintain process parameters.

The solid polysilicon added to the crucible melt is typically granular polysilicon, and it is fed into the crucible using a polysilicon feeder that is optimized for use with granular polysilicon. In some cases, solid polysilicon added to a crucible melt is chunk polysilicon. Chunk polysilicon has a greater size (e.g., in at least one dimension) than that of granular polysilicon. Chunk polysilicon is fed into a crucible using a polysilicon feeder optimized for use with chunk polysilicon. A more satisfactory apparatus and method for feeding either chunk or granular polysilicon is needed.

<CIT> describes a polysilicon supply system comprising a support unit which is provided above a drive device; an enclosure which is provided above the support unit; a fixed-amount supply unit which is provided inside the enclosure; a hopper which is provided on one side above the enclosure, and supplies a raw material to the fixed-amount supply unit; a supply tube which supplies, into a crucible, the fixed amount of raw material discharged from the fixed-amount supply unit. <CIT> describes a method for recharging a crucible with polycrystalline silicon comprises adding flowable chips to a crucible used in a Czochralski-type process using feeder equipment such as vibration feeder systems.

The present invention is directed to a feed assembly for supplying polysilicon to a growth chamber for growing a crystal ingot from a melt. The feed assembly includes one or more support rails for receiving and interchangeable tray, e.g., one of a granular tray and a chunk tray. The feed assembly also includes a feed material reservoir positioned above the support rail(s) to feed the tray. The feed assembly also includes a tube for supplying polysilicon to the growth chamber. The tray is rotatable with respect to the tube and rotates between a feeding position in which polysilicon may enter the growth chamber and a parked position in which the tray may be interchanged.

According to a preferred embodiment, a valve mechanism controls the flow of polysilicon from the interchangeable tray of the polysilicon feed assembly to the growth chamber for growing a crystal ingot from a melt. In a particular embodiment, the valve mechanism may include a seal that selectively obstructs an exit of the interchangeable tray; a driver is configured to raise and lower the seal between a sealed position obstructing the exit and an open position in which the seal does not obstruct the exit; a linkage connects the seal to the driver; and the seal is shaped to permit a gap between the seal and a portion of the exit of the interchangeable tray such that granular polysilicon within the exit does not prevent a seal between the seal and the exit.

According to a preferred embodiment, the vibrator is a magnetic pulse vibrator that controls the flow of polysilicon from the interchangeable tray, e.g., from one of either a granular tray or a chunk tray of the polysilicon feed assembly to the growth chamber for growing a crystal ingot from a melt. The magnetic pulse vibrator includes an electromagnetic energy source that vibrates the tray through the emission of electromagnetic energy. The magnetic pulse vibrator also includes a controller that controls a feed rate of the tray through control of the voltage supplied to the electromagnetic energy source.

According to a preferred embodiment, the interchangeable tray is an interchangeable granular tray which includes an exterior portion. The exterior portion removably receives a support rail of the feed assembly. The interchangeable granular tray further includes an interior profile that receives granular polysilicon from a feed material reservoir of the feed assembly. The granular tray is removable from the feed system.

According to another preferred embodiment, the interchangeable tray is an interchangeable chunk tray which includes an exterior portion. The exterior portion removably receives a support rail of the feed assembly. The interchangeable chunk tray further includes an interior profile that receives chunk polysilicon from a feed material reservoir of the feed assembly. The chunk tray is removable from the feed system.

The present invention is also directed to a valve mechanism for controlling the flow of polysilicon from an interchangeable tray of a polysilicon feed assembly to a growth chamber as defined in the claims.

Various refinements exist of the features noted above. Further features may also be incorporated in the above-mentioned embodiments of the invention. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to any of the illustrated embodiments may be incorporated into any of the above-described embodiments, alone or in any combination.

Referring now to <FIG>, a polysilicon feeder <NUM> of one embodiment includes a hopper <NUM>, an interchangeable tray <NUM>, a vibrator <NUM>, and a guide tube <NUM>. Hopper <NUM> is configured to receive polysilicon to be supplied to one or more crucibles in a growth chamber (not shown). Note that any type of crucible and growth chamber may be used. Hopper <NUM> is configured to receive granular polysilicon or chunk polysilicon. Chunk polysilicon typically has a size of between <NUM> and <NUM> millimeters (e.g., the largest dimension), and granular polysilicon typically has a size between <NUM> and <NUM> microns. Hopper <NUM> feeds polysilicon into interchangeable tray <NUM>.

Interchangeable tray <NUM> may be either a granular tray <NUM> (shown in <FIG>) for use with granular polysilicon loaded in hopper <NUM> or a chunk tray <NUM> (shown in <FIG>) for use with chunk polysilicon loaded in hopper <NUM>. Interchangeable tray <NUM> receives polysilicon from hopper <NUM> and provides polysilicon to guide tube <NUM> when driven by vibrator <NUM>.

Using interchangeable tray <NUM> allows polysilicon feeder <NUM> to be quickly and easily adapted for use with either granular polysilicon or chunk polysilicon. Interchangeable tray <NUM> may be removed and replaced with a second interchangeable tray that is configured for use with a different type of polysilicon. For example, a granular tray <NUM> may have features such as a shallow depth relative to that of a chunk tray <NUM>, a funnel portion, a substantially vertical exit portion, or other features suitable for use with granular polysilicon. A chunk tray <NUM> may have features such as a greater depth than that of the granular tray <NUM>, sloped sides, a slopping exit, or other features suitable for use with chunk polysilicon. Switching one type of interchangeable tray <NUM> for another converts polysilicon feeder <NUM> for use with a different type of polysilicon. For example, removing a granular tray <NUM> and replacing it with a chunk tray <NUM> converts polysilicon feeder <NUM> from a feeder to be used with granular polysilicon to a feeder to be used with chunk polysilicon. Interchangeable trays <NUM>, including granular trays <NUM> and chunk trays <NUM>, are described in greater detail with reference to <FIG>.

Polysilicon feeder <NUM> includes a vibrator <NUM> that causes interchangeable tray <NUM> to vibrate. Vibrator <NUM> is a magnetic pulse vibrator that vibrates interchangeable tray <NUM> using magnetic pulses. The magnetic pulse vibrator is discussed in greater detail with reference to <FIG> and <FIG>. Alternatively, vibrator <NUM> is an electromechanical or mechanical vibrator. For example, vibrator <NUM> may be or include a reciprocating piston, driven three or four bar mechanism, rotary electric vibrator, or other suitable system for generating vibration.

By vibrating interchangeable tray <NUM>, vibrator <NUM> causes polysilicon to exit interchangeable tray <NUM> (e.g., through an exit opposite hopper <NUM>). Polysilicon exiting interchangeable tray <NUM> enters guide tube <NUM>. By controlling the vibration of vibrator <NUM>, and the vibration of interchangeable tray <NUM>, the feed rate of polysilicon from polysilicon feeder <NUM> is controlled. A control system (e.g., a programmable logic controller) may control vibrator <NUM>.

Polysilicon feeder <NUM> also includes a guide tube <NUM>. Guide tube <NUM> is configured to receive polysilicon that exits interchangeable tray <NUM> due to vibration caused by vibrator <NUM>. Guide tube <NUM> directs polysilicon from polysilicon feeder <NUM> to enter a crucible used in generating a silicon crystal using the Czochralski method. Guide tube <NUM> may be positioned such that polysilicon is added to a melt within the crucible as a silicon crystal is drawn out of the melt. For example, guide tube <NUM> may be positioned off center relative to a crystal puller.

Referring now to <FIG>, the polysilicon feeder <NUM> shown in <FIG> is depicted in greater detail. Polysilicon feeder <NUM> includes valve mechanism <NUM> in some embodiments. Valve mechanism <NUM> is configured to engage and disengage with interchangeable tray <NUM> to stop the flow of polysilicon into guide tube <NUM>. For example, vibrator <NUM> may be turned off or otherwise not vibrating interchangeable tray <NUM>, but movement of polysilicon feeder <NUM> may none the less cause polysilicon to exit interchangeable tray <NUM> and enter guide tube <NUM>. Valve mechanism <NUM> may be engaged (e.g., as controlled by a control system such as a programmable logic controller) and cause a seal to engage (e.g., seat with) an exit portion of interchangeable tray <NUM>. The seal of valve mechanism <NUM> prevents polysilicon from exiting interchangeable tray <NUM> and entering guide tube <NUM>.

As shown in <FIG>, hopper <NUM> supplies polysilicon (e.g., granular or chunk polysilicon) to interchangeable tray <NUM>. In this embodiment, hopper <NUM> includes an outlet that is positioned above interchangeable tray <NUM> opposite an exit of interchangeable tray <NUM>. The outlet supplies guide tube <NUM> with polysilicon when vibrator <NUM> vibrates interchangeable tray <NUM>. The vibration of interchangeable tray <NUM> by vibrator <NUM> causes polysilicon to exit interchangeable tray <NUM> from the exit and enter guide tube <NUM>. Guide tube <NUM> includes an exit into the crucible used for crystal generation such that polysilicon entering guide tube <NUM> exits into the crucible.

In this embodiment, vibrator <NUM> includes a magnetic pulse vibrator. The magnetic pulse vibrator controls the flow of polysilicon from interchangeable tray <NUM> (e.g., one of either a granular tray <NUM> or a chunk tray <NUM>) to the crucible. The magnetic pulse vibrator includes an electromagnetic energy source that vibrates one of either the granular tray <NUM> or the chunk tray <NUM> through the emission of electromagnetic energy. The magnetic pulse vibrator also includes a controller that controls a feed rate of one of either the granular tray <NUM> or the chunk tray <NUM> through control of the voltage supplied to the electromagnetic energy source.

In one embodiment, the magnetic pulse vibrator uses magnetic pulses to drive a spring-biased table. The magnetic pulse may be generated, for example, by selectively applying a voltage having a variable amplitude and/or variable frequency of application to a coil. This results in a magnetic pulse that interacts with a core to drive (e.g., move or displace) the core. The core is connected to the table such that when the core is displaced by a magnetic pulse from the coil, the core displaces the table. A spring or other suitable mechanism biases the table and connected core to a rest position from which the core is displaced by the magnetic pulse. The movement of the core generates vibrations that in turn drive interchangeable tray <NUM>. For example, interchangeable tray <NUM> may be connected to the table which is driven by the connected core and the coil.

The magnetic pulse vibrator may be controlled by both voltage and frequency. The voltage and frequency are linked control parameters which interact to control the magnetic pulse vibrator and feed rate of polysilicon feeder <NUM>. By varying the amplitude of the voltage applied, the strength of the magnetic pulse and the amount of displacement of the core and table is varied. This control determines the strength of the vibration applied to interchangeable tray <NUM>. By varying the frequency with which the voltage is applied, the frequency of the vibration applied to interchangeable tray <NUM> is controlled. One or more of voltage frequency and voltage amplitude may be used to vibrate interchangeable tray <NUM> to meet a set point for a polysilicon feed rate (e.g., in kg of polysilicon per hour).

In an alternative embodiment, the magnetic pulse vibrator drives interchangeable tray <NUM> directly with magnetic pulses. For example, interchangeable tray <NUM> may include one or more portions that are magnetic and that are displaced by the magnetic pulses generated by the magnetic pulse vibrator.

Referring now to <FIG>, a granular tray <NUM> is shown according to one embodiment. Granular tray <NUM> is one type of interchangeable tray <NUM> for use with granular polysilicon and polysilicon feeder <NUM> shown in <FIG> and <FIG>. Granular tray <NUM> includes an exterior portion that removably receives a support rail of the feed assembly, and granular tray <NUM> includes an interior profile that receives granular polysilicon from a feed material reservoir (e.g., hopper <NUM>) of polysilicon feeder <NUM>. The interior profile of granular tray <NUM> has a depth less than a second interior profile of a chunk tray <NUM> (shown in <FIG>).

In operation, granular tray <NUM> may be removed from the feed system of polysilicon feeder <NUM>. This allows granular tray <NUM> to be replaced by chunk tray <NUM> when polysilicon feeder <NUM> is to be used with chunk polysilicon rather than granular polysilicon. Granular tray <NUM> is interchangeable with chunk tray <NUM> as polysilicon feeder <NUM> includes support rails and a cavity sized to receive either granular tray <NUM> or chunk tray <NUM>. The exterior portion of granular tray <NUM> includes two exterior channels <NUM> on opposing sides that removably receive the support rails of the feed assembly included in polysilicon feeder <NUM>. This allows granular tray <NUM> to be removed and replaced with chunk tray <NUM>. As explained in greater detail with reference to <FIG>, chunk tray <NUM> includes an exterior channel having the same dimensions as exterior channel <NUM> of granular tray <NUM>. In some embodiments, granular tray <NUM> and chunk tray <NUM> have the same outer dimensions to facilitate interoperability with polysilicon feeder <NUM>. Chunk tray <NUM> can similarly be removed and replaced with granular tray <NUM>.

Referring now to <FIG>, granular tray <NUM> includes an inner profile defined by at least a bottom <NUM>, a wall <NUM>, a funnel <NUM>, and an exit <NUM>. The interior profile of granular tray <NUM> receives granular polysilicon from hopper <NUM>. The granular polysilicon is received by the portion of the inner profile opposite exit <NUM> and prior to funnel <NUM>. For example, the portion of the interior profile that receives granular polysilicon may be substantially circular tapering to funnel <NUM>, as shown. Bottom <NUM> is recessed from a top surface <NUM> of granular tray <NUM> by a depth defined by wall <NUM>. Wall <NUM> may be tapered or radiused to reduce the likelihood of granular polysilicon becoming trapped at the corner of or right angle formed between wall <NUM> and bottom <NUM>. Granular tray <NUM> has a constant depth with bottom <NUM> at the same depth relative to top surface <NUM> for the entirety of bottom <NUM>.

In alternative embodiments, bottom <NUM> includes a first portion at a first depth prior to funnel <NUM> and a second portion at a greater depth past funnel <NUM>, the second portion including exit <NUM>. This stepped bottom <NUM> may facilitate feeding of granular polysilicon by granular tray <NUM>. In alternative embodiments, bottom <NUM> has other configurations. For example, bottom <NUM> may include a sloped portion that slopes towards exit <NUM>.

Funnel <NUM> is defined by raised sections that extend above bottom <NUM>. The raised sections have a height less than that of top surface <NUM>. In alternative embodiments, the raised sections forming funnel <NUM> extend to the same height as that of top portion <NUM>. Funnel <NUM> facilitates feeding of granular polysilicon when granular tray <NUM> is vibrated by vibrator <NUM>. For example, funnel <NUM> may prevent granular polysilicon exiting hopper <NUM> from exiting granular tray <NUM> through exit <NUM> when vibrator <NUM> is not driving granular tray <NUM>. Funnel <NUM> may impede the travel of granular polysilicon from hopper <NUM> when granular tray <NUM> is not vibrating.

Granular tray <NUM> includes outer dimensions defined by exterior surfaces <NUM> including at least the top surface <NUM>, the exterior channels <NUM> formed in side portions <NUM>, a side <NUM>, an angled side <NUM>, a front <NUM>, a back <NUM>, and a bottom <NUM>. The dimensions and exterior surfaces of granular tray <NUM> are sized and shaped such that granular tray <NUM> can be inserted into polysilicon feeder <NUM>. For example, the height of granular tray <NUM>, defined by top surface <NUM> and bottom <NUM>; the width of granular tray <NUM>, defined by side portions <NUM>; and the length of granular tray <NUM>, define by front <NUM> and back <NUM>, are sized to fit within an opening in polysilicon feeder <NUM>. When inserted into the opening in polysilicon feeder <NUM>, granular tray <NUM> is positioned below hopper <NUM> and above vibrator <NUM>. Exterior channels <NUM> receive guide rails of polysilicon feeder <NUM> that position granular tray <NUM> vertically. Bottom <NUM> may be in contact with vibrator <NUM> or a vibration table driven by vibrator <NUM>. Alternatively, granular tray <NUM> is supported above vibrator <NUM> by the guide rails and exterior channel <NUM>. Top surface <NUM> may be in contact with hopper <NUM> or other portions of portions of polysilicon feeder <NUM>.

Exterior channels <NUM> are included within side portions <NUM> that extend from side <NUM>. Side portions <NUM>, exterior channel <NUM>, and side <NUM> extend from back <NUM>. Sides <NUM> taper to front <NUM> creating angled sides <NUM>. In some embodiments, the opening in polysilicon feeder <NUM> is dimensioned such that granular tray <NUM> may not be fully inserted if inserted back <NUM> first rather than front <NUM> first.

Referring now to <FIG>, exterior channels <NUM> included in side portion <NUM> extend forward from back <NUM>. Exterior channels <NUM> are disposed above bottom <NUM>. Alternatively, exterior channels <NUM> may be level with bottom <NUM>. In other embodiments, exterior channels <NUM> include a single flange that extends from side <NUM>, side portion <NUM>, or another suitable surface. The single flange is positioned above the guide rails when granular tray <NUM> is inserted into polysilicon feeder <NUM>. Sides <NUM> taper to front <NUM> and include angled portions <NUM>. In still other embodiments, exterior channels <NUM> or other support mechanisms (e.g., flanges) may be positioned in other locations (e.g., extending backward from a front end of side <NUM>).

Bottom <NUM> is recessed from top surface <NUM>. Wall <NUM> extends downward from top surface <NUM> to bottom <NUM> and is chamfered at the junction between bottom <NUM> and wall <NUM>. Funnel <NUM> is located between back <NUM> and exit <NUM> such that a flow of polysilicon entering granular tray <NUM> from hopper <NUM> must pass through a narrower section defined by funnel <NUM> before exiting granular tray <NUM>. Exit <NUM> is circular with a chamfered opening portion <NUM> that has a decreasing radius to a second portion <NUM> of exit <NUM>. Second portion <NUM> has a fixed radius. As described with reference to <FIG>, these features in combination with valve mechanism <NUM> prevent polysilicon from inadvertently exiting granular tray <NUM> into guide tube <NUM> for supplying polysilicon to a crucible used in generating a semiconductor crystal.

Referring now to <FIG>, a chunk tray <NUM> of one embodiment is another type of interchangeable tray <NUM> for use with chunk polysilicon and polysilicon feeder <NUM> shown in <FIG> and <FIG>. Chunk tray <NUM> has the same outer dimensions as granular tray <NUM>. This allows chunk tray <NUM> and granular tray <NUM> to be used interchangeably with polysilicon feeder <NUM>.

Referring specifically to <FIG>, chunk tray <NUM> includes exterior surfaces <NUM> defined by at least the top surface <NUM>, the exterior channel <NUM> formed in the side portion <NUM>, the side <NUM>, the angled side <NUM>, the front <NUM>, the back <NUM>, and the bottom <NUM>. Exterior surfaces <NUM> of chunk tray <NUM> have the same dimensions and configuration as exterior surfaces <NUM> of granular tray <NUM>. Chunk tray <NUM> includes two exterior channels <NUM> that removably receive the support rails of the feed assembly of polysilicon feeder <NUM>. The exterior channels <NUM> are located on opposing sides of chunk tray <NUM>. The exterior surfaces <NUM> of chunk tray <NUM> perform the same functions as the exterior surfaces of granular tray <NUM> previously described herein in reference to <FIG>.

In operation, chunk tray <NUM> is inserted into polysilicon feeder <NUM> such that the support rails of polysilicon feeder <NUM> are inserted within channels <NUM>. The support rails support chunk tray <NUM>. The support rails and channels <NUM> allow chunk tray <NUM> to be removed and replaced with a granular tray <NUM>.

Referring now to <FIG>, chunk tray <NUM> includes an interior profile that receives chunk polysilicon from a feed material reservoir (e.g., hopper <NUM>) of polysilicon feeder <NUM>. The interior profile of chunk tray <NUM> is defined by a bottom <NUM>, a bowl <NUM>, sides <NUM>, and a wall <NUM>. Wall <NUM> is perpendicular to top surface <NUM> and extends downward from top surface <NUM>. Bowl <NUM> extends from wall <NUM> to bottom <NUM> and is located opposite an exit <NUM>. When inserted into polysilicon feeder <NUM>, bowl <NUM> is positioned beneath an outlet of hopper <NUM> such that polysilicon exiting hopper <NUM> enters chunk tray <NUM> over bowl <NUM>. Bowl <NUM> is generally circular or semicircular and has a profile, viewed from above, of a fraction of a circle (e.g., <NUM>/<NUM> of a circle or <NUM>/<NUM> of a circle). Bowl <NUM> has a first radius at the junction between the top of bowl <NUM> and wall <NUM>. Bowl <NUM> has a second radius, less than the first radius, at the junction between bowl <NUM> and bottom <NUM>. The radius of bowl <NUM> decreases linearly from the first radius to the second radius. In alternative embodiments, bowl <NUM> may have other shapes.

Sides <NUM> extend downward from wall <NUM> and meet bottom <NUM>. Sides <NUM> also extend horizontally between bowl <NUM> and wall <NUM> opposite bowl <NUM>. Sides <NUM> are angled to extend inwards toward exit <NUM> as sides <NUM> approach bottom <NUM>. Exit <NUM> has a circular opening through bottom <NUM>. Bottom <NUM> is flat. In alternative embodiments, bottom <NUM> is slopped towards exit <NUM>.

Referring now to <FIG>, a section of chunk tray <NUM> is shown. Wall <NUM> extends downward from top surface <NUM> and meets bowl <NUM> and sides <NUM>. Wall <NUM>, bowl <NUM>, and sides <NUM> funnel toward the centerline of chunk tray <NUM> running from back <NUM> to front <NUM>. Bowl <NUM> extends approximately one third of the length of chunk tray <NUM> with sides <NUM> approximately two thirds the length of chunk tray <NUM>. Sides <NUM> have a first portion of constant height followed by a second portion in which the height decreases as the sides <NUM> near exit <NUM>. In this embodiment, the height decreases first non-linearly and then linearly. In alternative embodiments, sides <NUM>, bowl <NUM>, or wall <NUM> may have different shapes or configurations.

Referring to <FIG>, chunk tray <NUM> has an interior profile (e.g., defined by wall <NUM>, bowl <NUM>, sides <NUM>, and bottom <NUM>) that differs from the interior profile of granular tray <NUM>. The interior profile of chunk tray <NUM> has a greater depth than the interior profile of granular tray <NUM>. The opening of exit <NUM> of the chunk tray is disposed lower above bottom <NUM> than the opening of exit <NUM> of granular tray <NUM>. Additionally, wall <NUM> of chunk tray <NUM> has a greater height than wall <NUM> of granular tray <NUM>. The deeper profile of chunk tray <NUM> facilitates feeding of chunk polysilicon.

Referring again to <FIG>, in operation, angled sides <NUM> and bowl <NUM> of chunk tray <NUM> facilitate feeding of polysilicon to exit <NUM>. The polysilicon enters bowl <NUM> from hopper <NUM> and is funneled toward exit <NUM> by bowl <NUM>, sides <NUM>, and bottom <NUM>. Chunk tray <NUM> is driven by vibrator <NUM> that causes the polysilicon to exit chunk tray <NUM> through exit <NUM>.

Granular tray <NUM> and chunk tray <NUM> are suitably made of, or include a substantial portion of, silicon. Use of silicon inhibits contamination of the crucible melt, for example, in the event that the tray is chipped. If the chip enters the melt and the tray is made of silicon, minimal contamination will result. In alternative embodiments, granular tray <NUM> and chunk tray <NUM> may be constructed of different material(s) such as polytetrafluoroethylene, quartz, or other suitable materials. For example, the interchangeable trays <NUM> may be constructed of one or more materials with a relatively high hardness, such as quartz, to resist chipping.

Referring now to <FIG>, chunk tray <NUM> is removably connected to vibrator <NUM> by receiving a pair of rails <NUM> in exterior channels <NUM>. Although depicted with chunk tray <NUM>, vibrator <NUM> may be similarly connected to granular tray <NUM>.

Each rail <NUM> is connected to a table <NUM> of vibrator <NUM>. For example, each rail <NUM> is connected to table <NUM> by brackets, fasteners, or other suitable components. Each rail <NUM> extends above table <NUM> and extends inward towards the center of table <NUM>. Each rail <NUM> extends for at least a portion of the length of table <NUM>. Each rail <NUM> further includes a rear stop <NUM> which prevents over insertion of chunk tray <NUM>. Each rear stop <NUM> extends inward towards the center of table <NUM> from each rail <NUM>.

When chunk tray <NUM> is attached to vibrator <NUM>, each rail <NUM> extends within a corresponding exterior channel <NUM>. Each rail <NUM> extends within side portion <NUM> in the space defined by exterior channel <NUM>. Interference between exterior channel <NUM> in side <NUM> and rail <NUM> prevents lateral movement and vertical movement of chunk tray <NUM>. The bottom <NUM> of chunk tray <NUM> rests on table <NUM>. The back <NUM> of chunk tray <NUM> is in contact with each rear stop <NUM>. Interference between back <NUM> and each rear stop <NUM> prevents rearward movement of chunk tray <NUM>. Granular tray <NUM> is connected to vibrator <NUM> by the pair of rails <NUM>, table <NUM>, and rear stops <NUM> in the same manner.

In some embodiments, chunk tray <NUM>, or granular tray <NUM>, is partially covered with cover <NUM>. Cover <NUM> includes lips which extend over top surface <NUM> and partially over side <NUM>, and angled side <NUM> to secure cover <NUM>.

Referring now to <FIG>, vibrator <NUM> and interchangeable tray <NUM> are movable between a feeding position (shown in <FIG>) and a parked position (shown in <FIG>). In the feeding position, vibrator <NUM> and interchangeable tray <NUM> are positioned such that an exit of interchangeable tray <NUM> is positioned above guide tube <NUM>. In some embodiments, guide tube <NUM> is in contact with interchangeable tray <NUM>.

In the parked position, vibrator <NUM> and interchangeable tray <NUM> are rotated away from guide tube <NUM>. For example, the parked position may be seventy degrees from the feeding position. The parked position provides access to interchangeable tray <NUM> such that interchangeable tray <NUM> may be replaced with a different interchangeable tray <NUM>. For example, in the parked position, a granular tray <NUM> may be replaced with a chunk tray <NUM>.

In operation, guide tube <NUM> is lowered. Vibrator <NUM> and interchangeable tray <NUM> are moved into the feeding position from the parked position prior to feeding polysilicon to a crucible. Vibrator <NUM> is rotated from the parked position to the feeding position. In one embodiment, vibrator <NUM> is rotated using a motor. In an alternative embodiment, vibrator <NUM> is rotated by hand. Interchangeable tray <NUM> rotates with vibrator <NUM> due to the connection described above. In some embodiments, guide tube <NUM> is contact with interchangeable tray <NUM>.

Once vibrator <NUM> and interchangeable tray <NUM> are in the feeding position, vibrator <NUM> is turned on. Vibrations from vibrator <NUM> cause polysilicon from interchangeable tray <NUM> to exit into guide tube <NUM>. Guide tube <NUM> guides the polysilicon exiting interchangeable tray <NUM> into a crucible. Hopper <NUM> feeds polysilicon into interchangeable tray <NUM> to replace polysilicon exiting interchangeable tray <NUM>. Vibrator <NUM> is turned off.

Vibrator <NUM> and interchangeable tray <NUM> are moved into the parked position from the feeding position. Vibrator <NUM> is rotated from the feeding position to the parked position. Interchangeable tray <NUM> rotates with vibrator <NUM>. In some embodiments, guide tube <NUM> is raised after vibrator <NUM> is rotated to the parked position.

While in the parked position, interchangeable tray <NUM> may be removed from vibrator <NUM>. For example, granular tray <NUM> may be removed from vibrator <NUM>. A replacement interchangeable tray <NUM>, for example a chunk tray <NUM>, may be connected to vibrator <NUM>. The parked position allows for the swapping of interchangeable trays <NUM>.

In some embodiments, a valve mechanism (shown in <FIG>) is used to seal exit <NUM> of granular tray <NUM> before granular tray <NUM> is moved from the feeding position to the parked position. The valve mechanism prevents polysilicon from exiting granular tray <NUM> due to the movement of granular tray <NUM> from the feeding position to the parked position. The valve mechanism rotates with vibrator <NUM> and interchangeable tray <NUM>. The valve mechanism is removably connected to granular tray <NUM>. For example, the valve mechanism may be connected to cover <NUM>. In alternative embodiments, the valve mechanism is connected to vibrator <NUM>.

Valve mechanism <NUM> controls the flow of polysilicon through exit <NUM> of granular tray <NUM>. As shown in <FIG>, valve mechanism <NUM> is in an open state. Valve mechanism <NUM> of this embodiment is not used with chunk tray <NUM> because the relatively larger size of chunk polysilicon prevents chunk polysilicon from inadvertently exiting chunk tray <NUM> (e.g., due to movement of polysilicon feeder <NUM>). The smaller size of granular polysilicon allows granular polysilicon to be forced or moved through exit <NUM> by movement of polysilicon feeder <NUM>, for example. Valve mechanism <NUM> seals exit <NUM> of granular tray <NUM>. In alternative embodiments, valve mechanism <NUM> is used in conjunction with both granular tray <NUM> and chunk tray <NUM>. Valve mechanism <NUM> includes a seal <NUM> and a driving system <NUM>.

Driving system <NUM> of this embodiment is a solenoid for moving seal <NUM> between a sealed position and an open position. In the sealed position (as shown in <FIG>), seal <NUM> obstructs or closes exit <NUM>. In the open position (as shown in <FIG>), seal <NUM> does not obstruct exit <NUM> for relatively free flow of material. Driving system <NUM> includes driver <NUM> that raises seal <NUM> when active, for example, by applying a magnetic field to linkage <NUM> extending through driver <NUM> and connected to seal <NUM>. Driver <NUM> may be a series of windings that are energized by a control circuit to apply a magnetic field to linkage <NUM>. The magnetic field causes linkage <NUM> to be driven upward. In alternative embodiments, driver <NUM> is a different mechanical or electromechanical system from providing linear motion such as a cam and camshaft, hydraulic actuator, or rack and pinion. Linkage <NUM> connects seal <NUM> to driving system <NUM> and when driven upward raises seal <NUM> to the open position.

Valve mechanism <NUM> is normally closed. When driver <NUM> is not active, the force of gravity causes seal <NUM> to lower into the sealed position. In some further embodiments, driving system <NUM> includes a spring to return seal <NUM> to the normally closed position. In alternative embodiments, valve mechanism <NUM> is normally open. A spring maintains linkage <NUM> and seal <NUM> in the open position. When activated, driver <NUM> applies a magnetic field to linkage <NUM> that drives linkage <NUM> downward causing sealing portion <NUM> to move to the sealed position.

Driving system <NUM> also includes an upper position switch <NUM> and a lower position switch <NUM>. Position switches <NUM>, <NUM> each include a lever positioned to interfere with a top portion <NUM> of linkage <NUM>. Interference between top portion <NUM> of linkage <NUM> and one of upper position switch <NUM> or lower position switch <NUM> causes the respective switch to provide an indication of the position of seal <NUM>, open and sealed, respectively.

Seal <NUM> is shaped to interface with exit <NUM> and bottom <NUM> of granular tray <NUM>. The shape of seal <NUM> obstructs exit <NUM> when in the sealed position and prevents polysilicon from exiting granular tray <NUM> through exit <NUM>. In the open position, seal <NUM> does not contact granular tray <NUM>. Seal <NUM> includes a first section <NUM>, a second section <NUM>, and a third section <NUM>. Each section corresponds to a different portion of granular tray <NUM> (e.g., angled portion <NUM> and second portion <NUM>) to facilitate obstruction of exit <NUM>. For example, exit <NUM> is circular when viewed from above and each section of seal <NUM> is circular when viewed from above.

Referring now to <FIG>, when in the sealed position, seal <NUM> obstructs exit <NUM> of granular tray <NUM>. Third section <NUM> of seal <NUM> has a radius less than the radius of second portion <NUM> of exit <NUM>. This allows third section <NUM> of seal <NUM> to enter second portion <NUM> of exit <NUM> when sealing exit <NUM>. Third section <NUM> of seal <NUM> may have a radius sufficiently large to create a running fit or interference fit with second portion <NUM> of exit <NUM>.

Second section <NUM> of seal <NUM> extends from third section <NUM> to first section <NUM>. Second section <NUM> has a decreasing radius from the larger radius of first section <NUM> to the smaller radius of third section <NUM>. The radius of second section <NUM> decreases linearly. The decreasing radius of second section <NUM> matches the decreasing radius of angled portion <NUM> of exit <NUM>. The radius of second section <NUM> decreases at the same rate as the radius of angled portion <NUM>. The slope of second section <NUM> is equal to that of angled portion <NUM>. When in the sealed position, second section <NUM> is in contact with angled portion <NUM> of exit <NUM>. This seals exit <NUM> and prevents polysilicon from exiting granular tray <NUM>. The height of second section <NUM> is less than the height of angled portion <NUM>. Second section <NUM> terminates at first section <NUM>.

First section <NUM> has a fixed radius equal to the largest radius of second section <NUM>. First section <NUM> extends upward from section <NUM> and is coupled to linkage <NUM>. First section <NUM> has a radius less than the largest radius of angled portion <NUM> of exit <NUM>. This creates a gap <NUM> between first section <NUM> and the opening of exit <NUM> when seal <NUM> is in the sealed position. First section <NUM> extends at least partially into angled portion <NUM> of exit <NUM>. First section <NUM> may also extend above exit <NUM>.

Gap <NUM> between seal <NUM> and exit <NUM> ensures that no granular polysilicon within exit <NUM> blocks seal <NUM> from contacting exit <NUM> which would prevent a seal from forming. Angled portion <NUM> of exit <NUM> causes any polysilicon within angled portion <NUM> to pass through exit <NUM> prior to seal <NUM> being moved to the sealed position. Angled portion <NUM> is free of polysilicon due to the angle. Therefore, no polysilicon can prevent a seal between seal <NUM> and exit <NUM> as second section <NUM> only contacts angled portion <NUM> where no polysilicon is present. First section <NUM> does not contact bottom <NUM> and is separated from bottom <NUM> by gap <NUM> such that polysilicon on bottom <NUM> does not impede seal <NUM> from sealing within exit <NUM>.

Referring now to <FIG>, in operation, driving system <NUM> raises and lowers seal <NUM> to seat and unseat with exit <NUM>. Seal <NUM> is normally closed to prevent polysilicon from inadvertently exiting through exit <NUM>. Driving system <NUM> lifts seal <NUM> into the open position by activating driver <NUM>. This allows polysilicon to exit granular tray <NUM> through exit <NUM>. Driving system <NUM> allows sealing mechanism <NUM> to return to the sealed position. Seal <NUM> contacts angled portion <NUM> of exit <NUM> to form a seal that prevents polysilicon from exiting granular tray <NUM> through exit <NUM>.

Position switches <NUM>, <NUM> are triggered when a top portion <NUM> of linkage <NUM> contacts a lever portion of limit switches <NUM>, <NUM>. When top portion <NUM> of linkage <NUM> contacts and moves the lever portion of upper position switch <NUM>, upper position switch <NUM> is triggered and indicates that seal <NUM> is in the open position. When top portion <NUM> of linkage <NUM> contacts and moves the lever portion of lower position switch <NUM>, lower position switch <NUM> is triggered and indicates that seal <NUM> is in the sealed position.

Referring now to <FIG>, the feed rate of polysilicon feeder <NUM> is controlled by varying the amount of voltage supplied to a magnetic pulse vibrator in some embodiments. The normalized voltage supplied to the magnetic pulse vibrator has a relationship with the normalized feed rate that corresponds to the voltage supplied to the magnetic pulse vibrator. By varying the voltage applied to the magnetic pulse vibrator, the feed rate of polysilicon feeder <NUM> is controllable. Based on the relationship between voltage and feed rate, a desired feed rate can be achieved by supplying a predetermined amount of voltage to the magnetic pulse vibrator. In some further embodiments, the magnetic pulse vibrator is also controlled by varying the frequency with which the voltage is supplied to the magnetic pulse vibrator.

The interchangeable trays described herein allow the polysilicon feeder to supply either granular or chunk polysilicon to a crucible for silicon crystal generation using the Czochralski method. By inserting the corresponding tray, the polysilicon feeder is capable of supplying a controlled rate of granular or chunk polysilicon to the crucible used in generating the silicon crystal. Advantageously, this allows the polysilicon feeder to use either source of polysilicon. For example, where only one source is available (e.g., chunk polysilicon), the corresponding tray is inserted into the polysilicon feeder and the crucible is supplied with polysilicon according to the parameters for crystal generation (e.g., a rate of polysilicon supply). Only a single source may be available due to supply issues or supply chain issues. The ability to easily switch from one polysilicon source to another provides greater supply security as different types of polysilicon may be used and therefore a greater number of supply sources are available. In some cases, it may be more economical to use a particular source of polysilicon (granular or chunk) depending on fluctuations in price. The polysilicon feeder is capable of operating more economically than a fixed source polysilicon feeder as the polysilicon feeder can adapt to either source using the interchangeable trays.

Granular polysilicon has several advantages including providing for easy and precise control of the feed rate due to the smaller size. However, the cost of granular polysilicon is typically higher than that of chunk polysilicon due to the chemical vapor deposition process or other manufacturing methods used in its production. Chunk polysilicon has the advantage of being cheaper and being capable of a higher feed rate given its larger size. By being capable of supplying either granular polysilicon or chunk polysilicon to a melt for crystal growth, the polysilicon feeder can selectively make use of the advantages of either polysilicon type and provides increased supply security by being compatible with either polysilicon type.

In some embodiments, the polysilicon feeder includes a magnetic pulse vibrator that supports the use of interchangeable polysilicon trays. The magnetic pulse vibrator vibrates either interchangeable polysilicon tray (e.g., the granular tray or the chunk tray) at variable rates using magnetic pulses. The rate may be controlled based on the frequency and/or magnitude of voltage supplied to the magnetic pulse vibrator. The magnetic pulse vibrator is capable of providing a wide range of vibration rates, magnitudes, or both which allows the polysilicon feeder to provide a specific feed rate when using either granular polysilicon, with the granular tray, or chunk polysilicon, with the chunk tray.

In further embodiments, the polysilicon feeder includes a valve mechanism. The valve mechanism engages and disengages with one of the two interchangeable trays (e.g., the granular tray) to selectively prevent polysilicon from feeding into the crucible regardless of the state of the vibrator driving the tray. For example, the polysilicon feeder may be moved or shifted (e.g., when the vibrator is not active). This movement may cause polysilicon to fall from the tray and enter the crucible at an unintended time. This polysilicon inadvertently added to the melt in the crucible functions as an impurity and degrades crystal quality. The valve mechanism engages with the interchangeable tray to seal an exit preventing polysilicon from exiting the interchangeable tray into the melt.

Claim 1:
A polysilicon feeder (<NUM>) for supplying polysilicon to a growth chamber for growing a single crystal ingot from a melt, the polysilicon feeder (<NUM>) comprising:
a tube (<NUM>) for supplying polysilicon exiting an interchangeable tray (<NUM>, <NUM>, <NUM>) to the growth chamber;
one or more support rails for receiving the interchangeable tray (<NUM>, <NUM>, <NUM>);
a vibrator (<NUM>) that vibrates the interchangeable tray (<NUM>, <NUM>, <NUM>), the interchangeable tray (<NUM>, <NUM>, <NUM>) and vibrator (<NUM>) being rotatable with respect to the tube (<NUM>) and rotating between a feeding position, in which an exit (<NUM>) of the interchangeable tray (<NUM>, <NUM>, <NUM>) is positioned above the tube (<NUM>) such that polysilicon may enter the growth chamber, and a parked position, in which the tray (<NUM>, <NUM>) may be interchanged; and
a feed material reservoir positioned above the support rail to feed the tray (<NUM>, <NUM>, <NUM>).