U.S. patent application number 09/683775 was filed with the patent office on 2002-05-30 for jet system for spherical shape devices.
This patent application is currently assigned to Ball Semiconductor, Inc.. Invention is credited to Hanabe, Murali, Patel, Nainesh J..
Application Number | 20020063351 09/683775 |
Document ID | / |
Family ID | 26959692 |
Filed Date | 2002-05-30 |
United States Patent
Application |
20020063351 |
Kind Code |
A1 |
Hanabe, Murali ; et
al. |
May 30, 2002 |
Jet system for spherical shape devices
Abstract
A system and method for making very small (e.g., 1 millimeter
diameter) spherical shaped devices is disclosed. The system
includes a supply system for providing predetermined amounts of raw
material into a chamber, which is used for melting the raw
material. The melted raw material is then provided to a dropper for
measuring predetermined amounts of the melted raw material
(droplets) and releasing the droplets into a drop tube, where they
are cooled and solidified into spherical shaped silicon devices.
The system includes a container of silicon powder in which the
solidified spherical shaped devices are received from the drop
tube, the container including a stirring mechanism for agitating
the silicon powder. The system also includes a separating device
for separating the powder from the solidified spherical shaped
devices after the devices have been received into the container
Inventors: |
Hanabe, Murali; (Plano,
TX) ; Patel, Nainesh J.; (Plano, TX) |
Correspondence
Address: |
HAYNES AND BOONE, LLP
901 MAIN STREET, SUITE 3100
DALLAS
TX
75202
US
|
Assignee: |
Ball Semiconductor, Inc.
415 Century Parkway
Allen
TX
75013
|
Family ID: |
26959692 |
Appl. No.: |
09/683775 |
Filed: |
February 13, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60279484 |
Mar 28, 2001 |
|
|
|
Current U.S.
Class: |
264/9 ; 264/13;
425/6 |
Current CPC
Class: |
C30B 11/00 20130101;
C30B 29/60 20130101 |
Class at
Publication: |
264/9 ; 264/13;
425/6 |
International
Class: |
B29B 009/00 |
Claims
1. A system for making spherical shaped devices, comprising: a
supply system for providing predetermined amounts of raw material
at a temperature at or above a melting point of the material, and
for moving the predetermined amounts of melted raw material without
physical contact so that a liquid surface tension of each
predetermined amount of melted raw material will cause the material
to solidify into a spherical shape device; a container of powder in
which the solidified spherical shaped devices are received from the
supply system; and means for separating the powder from the
solidified spherical shaped devices after the devices have been
received.
2. The system of claim 1 wherein the supply system includes: a
first chamber for containing the raw material in a liquid state;
and a first dropper registering with the first chamber for forming
the predetermined amounts of melted raw material.
3. The system of claim 2 wherein the supply system further
includes: an inlet for receiving a gas to facilitate the formation
of the predetermined amounts of melted raw material by the first
dropper.
4. The system of claim 2 wherein the supply system further
includes: a vibrator connected to the first dropper to facilitate
the formation of the predetermined amounts of melted raw material
by the first dropper.
5. The system of claim 2 wherein the supply system includes: a
second chamber for containing the raw material in a liquid state;
and a second dropper registering with the first chamber for
providing the melted raw material to the first chamber and
maintaining a relatively constant supply of the melted raw material
in the first chamber.
6. The system of claim 1 wherein the container includes: means for
agitating the powder in which the solidified spherical shaped
devices are received and moving the powder and devices towards the
separation means.
7. The system of claim 1 wherein the separator includes: an
enclosure including an input for receiving the receiver material
and the devices, a first outlet for outputting the devices and a
second outlet for outputting the receiver material; first and
second chambers defined within the enclosure, the first chamber
registering with the input and the first outlet and the second
chamber registering with the second outlet; a separator device
positioned between the first and second chambers, the separator
device having at least one opening having a size that is less than
a size of the device but greater than a size of the receiver
material; and means for providing a negative pressure to the second
chamber to encourage the receiver material to flow from the first
chamber, through the at least one opening, and into the second
chamber.
8. The system of claim 1 wherein the separator includes a wire
mesh.
9. The system of claim 8 wherein the wire mesh includes a plurality
of openings with a size less than one half the size of the device
but greater than the size of the receiver material.
10. The system of claim 7 wherein the separator further includes: a
third outlet for registering the pressure means with the second
chamber.
11. The system of claim 7 wherein the first outlet has a positive
pressure, as compared to the negative pressure of the second
chamber.
12. The system of claim 7 wherein the second chamber facilitates
returning the separated receiver material back to the
container.
13. A method for making spherical shaped semiconductor devices from
molten raw material, the method comprising: dropping predetermined
amounts of the molten raw silicon material into a drop tube;
solidifying the predetermined amounts inside the drop tube so that
a liquid surface tension of each predetermined amount will cause
the material to form a spherical shape device; and receiving the
solidified spherical devices into a container of silicon
powder.
14. The method of claim 13 further comprising: separating the
powder from the solidified spherical shaped devices after the
devices have been received.
15. The method of claim 13 further comprising: forming the
predetermined amounts of melted raw material using a pressurized
gas and a dropper.
16. The method of claim 13 further comprising: forming the
predetermined amounts using a vibrator connected to a dropper.
17. The method of claim 13 further comprising: agitating the powder
in which the solidified spherical shaped devices are received.
18. The method of claim 13 further comprising: stirring the powder
in which the solidified spherical shaped devices are received.
19. A system for making spherical shaped silicon devices,
comprising: a supply system for providing predetermined amounts of
raw material into a chamber; the chamber for melting the raw
material; a dropper for measuring predetermined amounts of melted
raw material (droplets) and releasing the droplets into a drop
tube; the drop tube for receiving the droplets and cooling the
droplets into solidified spherical shaped silicon devices; a
container of silicon powder in which the solidified spherical
shaped devices are received from the drop tube, the container
including a stirring mechanism for agitating the silicon powder;
and a separating device for separating the powder from the
solidified spherical shaped devices after the devices have been
received into the container.
20. The system of claim 19 wherein the stirring mechanism of the
container also services to move the received spherical shaped
devices and a portion of the silicon powder towards the separating
device.
Description
BACKGROUND
[0001] The invention relates generally to semiconductor devices,
and more particularly, to a system and method for creating
three-dimensional semiconductor devices.
[0002] This disclosure claims the benefit of U.S. Ser. No.
60/279,484, filed Mar. 28, 2001.
[0003] In U.S. Pat. No. 5,955,776, which is hereby incorporated by
reference, a method and apparatus for manufacturing
spherical-shaped semiconductor integrated circuit devices is
disclosed. Although certain systems and methods for performing
various processing operations are discussed in the above-referenced
patent, it is desired to further improve on the operations. For
example, in making a p-n junction diode, a first type (e.g. n-type)
outer layer is diffused onto a second type (e.g., p-type) spherical
shaped semiconductor substrate. It is desired that both the outer
layer and the inner substrate are maintained at an appropriate
shape, thickness, and diffusion concentration.
[0004] In U.S. patent Ser. Nos. 09/490,650 and 09/489,782, which
are hereby incorporated by reference, methods for doping material
on a spherical shaped substrate in a non-contact environment are
disclosed. These methods can be used to make spherical p-n junction
diodes for solar cell applications. It is desired, however, to make
uniform sized spherical p-n diodes in a continuous operation (e.g.,
a single step).
[0005] In U.S. patent Ser. Nos. 09/363,420 and 09/672,566, which
are hereby incorporated by reference, methods for making single
crystal devices and for making uniformly thick p-n junctions on
these devices are disclosed, respectively. It is desired, however,
to better automate the production of these devices in a highly
manufacturable setting.
SUMMARY
[0006] A technical advance is achieved by a new and improved jet
system for making spherical shaped devices. In one embodiment, the
system includes a supply system for providing predetermined amounts
of raw material at a temperature at or above a melting point of the
material, and for moving the predetermined amounts of melted raw
material without physical contact so that a liquid surface tension
of each predetermined amount of melted raw material will cause the
material to form into a spherical shape device. The system also
includes a container of powder in which the solidified spherical
shaped devices are received from the supply system and means for
separating the powder from the solidified spherical shaped devices
after the devices have been received.
[0007] In another embodiment, the system includes a supply system
for providing predetermined amounts of raw material into a chamber,
which is used for melting the raw material. The melted raw material
is then provided to a dropper for measuring predetermined amounts
of the melted raw material (droplets) and releasing the droplets
into a drop tube, where they are cooled and solidified into
spherical shaped silicon devices. The system includes a container
of silicon powder in which the solidified spherical shaped devices
are received from the drop tube, the container including a stirring
mechanism for agitating the silicon powder. The system also
includes a separating device for separating the powder from the
solidified spherical shaped devices after the devices have been
received into the container.
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG. 1 is a flow chart of a new and improved processing flow
for creating spherical shaped devices according to one embodiment
of the present invention.
[0009] FIG. 2 is a diagram of a feeder device, such as can be used
in the processing flow of FIG. 1.
[0010] FIGS. 3-4 are diagrams of a dropper device, such as can be
used in the processing flow of FIG. 1.
[0011] FIG. 5 is a diagram of a receiver device, such as can be
used in the processing flow of FIG. 1.
[0012] FIGS. 6-7 are diagrams of a separator device, such as can be
used in the processing flow of FIG. 1.
DETAILED DESCRIPTION
[0013] The present disclosure provides many different embodiments,
or examples, for implementing different features of the invention.
Specific examples of components, sizes, and arrangements are
described below to simplify the present disclosure and are not
intended to limit the invention.
[0014] Referring to FIG. 1, the reference numeral 10 designates, in
general, one embodiment of a processing flow for making spherical
shaped semiconductor devices. The processing flow 10 utilizes a
feeder system 12 that provides continuous feeding of raw material
and prevents undesired material and/or fluids from entering other
components. The feeder system 12 provides the material to a dropper
14, which is used to make the spherical shaped semiconductor
devices. The spherical shaped semiconductor devices are received
into a receiver 16, which include a soft powder-like refractory
receiving material, such as quartz. The devices and receiving
material are then provided to a separator 18 where the receiving
material is separated and recycled.
[0015] The following discussion provides many different embodiments
for different systems that can be used in the processing flow 10.
Each of the embodiments are different, but may include similar
components that are similarly numbered.
[0016] Referring now to FIG. 2, in one embodiment of the feeder
system 12, raw material Si 20 is received in the form of chunks,
powder or granules into a receiver 22. The receiver 22 includes a
sensor 24 for detecting the raw material and ensuring a continuous
feeding of raw material into the feeder. The flow of the raw
material 20 is controlled by two valves 26, 28. In addition, an
argon gas is controlled by valves 28 and 30.
[0017] The feeder 12 is designed to ensure continuous feeding of
the raw material 20 into the dropper system 14, while at the system
eliminating ingress of atmosphere into a nozzle (FIG. 3) of the
dropper. When the first valve 26 is opened, the raw material 20
will drop into a first tube portion 34. Thereafter, the first valve
26 is closed and the third valve 30 is opened to introduce Argon
through a first pipe 35. When the second valve 28 is opened the
feed will be dropped into the nozzle. The second valve 28 and the
third valve 30 are thereafter closed. In one embodiment, the
dropper 14 is as disclosed in presently incorporated U.S. patent
Ser. No. 09/672,566.
[0018] Referring now to FIGS. 3 and 4, in other embodiments of the
feeder system 12, the flow of the raw material 20 is controlled by
two shutters 36, 38. In the embodiment of FIG. 3, a second Argon
pipe 39 is also used to introduce Argon to the operation.
[0019] The feeder system 12 provides the raw material 20 to the
receiver system 14, where it proceeds to a chamber 40. The raw
material is melted by a furnace 42 into a liquid state (designated
as liquid material 44), which in the case of pure silicon is near
1400.degree. C. In some embodiments, such as is shown in FIG. 4,
the chamber 40 is attached to a first vibration device 46, such as
a piezo-electric vibrator (PZT). The first PZT 46 encourages the
liquid material 44 to move through a first nozzle 47 at a
predetermined rate into a second chamber 48. In addition, a gas
(e.g., Argon) may be supplied through a first pipe 35 to apply a
pressure to the first chamber 40 and further help control the flow
of the liquid material into the second chamber 48.
[0020] The second chamber 48 receives the liquid material 44 from
the first chamber 40 and feeds it into a jet nozzle 50, that is
controlled by a second vibration device 52. The nozzle 50 and
second vibration device 52 can thereby produce liquid droplets 54
of a predetermined size, e.g. about one millimeter. In addition, a
gas (e.g., Argon) may be supplied through a second pipe 56 to apply
a pressure to the second chamber 48 and further help control the
creation of the liquid droplets 54.
[0021] Referring now to FIG. 5, in one embodiment of the receiver
16, the liquid droplets 54 can fall, without contact, through a
drop tube 70. The rate at which the droplets move can be
controlled, such as through a pressure or a moving fluid through
the drop tube 70. Eventually, the droplets solidify into spheres
72. The temperature of the spheres 72 is relatively high, such as
between 1000.degree.-1300.degree. C. (near the melting point of
silicon).
[0022] The solidified spheres 72 are then received into a container
74. In the present embodiment, the container 74 is a furnace. The
furnace 74 includes a powdered refractory material (e.g., quartz
powder, silica, or ceramic powder) 76, which is heated to about
1000.degree.-1300.degree. C. The powder 76 is continually stirred
by a quartz mixing rod 78 connected to a motor 80. The stirring
exposes fresh powder 76 to the falling spheres 72. The powder 76
thereby provides a soft landing for the spheres 72.
[0023] Referring again to FIG. 1, the separator 18 receives the
spheres 72 and powder 76 from the furnace. It is understood that
there may be one or more separators 18 to repeatedly separate the
powder 76 from the spheres 72. The spheres 72 can be provided to
other downstream processing operations and the powder 76 can be
returned to the receiver 16.
[0024] Referring now to FIG. 6, in one embodiment the separator 18
includes an enclosure 112 having an inlet opening 114 and three
outlet openings 116, 118, 120. The outlet opening 116 is located
diametrically opposite the inlet opening 114. The enclosure 112
defines two chambers 122, 124. The chamber 122 is a separation
chamber for receiving a supply of spheres 72 and powder 76 and the
chamber 124 is a reservoir for receiving, storing and expelling the
separated powder 76 through the outlet 118. The chamber 122 and
reservoir 124 are connected by a neck portion 128.
[0025] A vertically extending conduit 130 is coaxially aligned with
the chamber 122, the reservoir 124 and the neck 126. The conduit
130 supplies a path between the outlet 116 and a separating device
132 located in the separation chamber 122. For the present
embodiment, the separating device 132 is a wire mesh formed into a
funnel shape. The wire mesh 132 includes a plurality of openings
having a diameter less than one-half the diameter of the sphere 72.
The wire mesh 132 includes an opening 134 that registers with the
inlet opening 114 to receive the supply of spheres 72 and powder
76. The wire mesh 132 also includes an outlet 136 that registers
with the conduit 130.
[0026] Although not shown, a vacuum source is connected to the
outlet 120 for providing a negative pressure inside the reservoir
124, the neck 128, and the separation chamber 122. The negative
pressure is not strong enough to lift either the spheres 72 or the
powder 76.
[0027] For the sake of reference, the pressure at several locations
inside the fluid separating processor 18 are identified. A pressure
P1 represents the pressure inside the reservoir 124; a pressure P2
represents the pressure inside the neck 128; a pressure P3
represents the pressure inside the separation chamber 122; a
pressure P4 represents the pressure at the conduit 130; and a
pressure P5 represents the pressure at the opening 114. The
following comparative relationships exist between the different
pressures P:
P1<P2 (1)
P2<P3 and P5 (2)
P4>P3 and P5 (3)
[0028] In operation, the supply of spheres 72 and powder 76 are
introduced into the opening 114. The spheres 72 are preferably of a
generally spherical shape and could be of the same type formed
according to the technique disclosed in the above-identified and
presently incorporated patent application Ser. No. 08/858,004. The
powder 76 may be a flow of constituents or liquids or the like. For
the sake of example, the powder 76 is a high-viscosity liquid from
a previous process.
[0029] When the spheres 72 and powder 76 enter the separation
chamber 122, they contact the wire mesh 134 and are propelled
towards the opening 136. In the preferred embodiment, the pressure
P3 assists this propelling action, but in other embodiments, the
momentum of the spheres 72 and powder 76, or other forces, may so
assist.
[0030] As the powder 76 is propelled towards the opening 136, it
flows through the wire mesh 134. The pressure P3 helps to draw the
powder 76 through the wire mesh 134. In some embodiments, the
(higher) pressure P4 from the conduit 130 also persuades the powder
76 to move through the wire mesh 134. In so doing, even highly
viscous fluid will be drawn through the wire mesh, despite the wire
mesh's narrow openings. The fluid is then drawn by either gravity
or by the pressure P2, or both, into the neck 128 and further drawn
(by gravity and/or the pressure P1) into the reservoir 124. It is
noted that the reservoir 124 is physically isolated from the
interior of the conduit 130 so that none of the powder 76 can enter
the conduit. The reservoir 124 maintains a portion of the powder 76
while draining out another portion through the outlet 118.
[0031] As the spheres 72 move toward the opening 136, they cannot
move through the wire mesh 134. Instead, the spheres 72 move into
the conduit 130 and then exit through the outlet 116.
[0032] Referring to FIG. 7, in another embodiment, the separator 18
includes an enclosure 142 having an inlet opening 144 and two
outlet openings 146, 148. The outlet opening 146 is opposite the
inlet opening 144. The enclosure 142 defines a chamber 152 and a
reservoir 154. The chamber 152 is a separation chamber for
receiving a supply of spheres 72 and powder 76 and the reservoir
154 receives and stores and expels the separated powder 76 using
the outlet 148. The chamber 152 and reservoir 154 are connected by
a slot 156.
[0033] A vertically extending conduit 158 is connected at one end
160 of the chamber 152 and passes through the reservoir 154. The
conduit 158 supplies a path between the outlet 146 and an opening
162 at the end 160 of the slot 156. For the present embodiment, the
slot 156 acts as a separation device by providing an opening with a
diameter less than the diameter of the sphere 72 (except at the
opening 162) but sufficiently large to allow the powder 76 to flow
there through.
[0034] Although not shown, a vacuum source is connected to the
outlet 148 for providing a negative pressure inside the reservoir
154, the slot 156, and the separation chamber 152. Also not shown,
a plurality of air inlets may be provided in the chamber 152. The
air inlets may be used to provide a dry, inert gas such as N2 to
the chamber.
[0035] For the sake of reference, the pressure at several locations
inside the fluid separating processor 18 are identified. A pressure
P10 represents the pressure inside the reservoir 154; a pressure
P11 represents the pressure the separation chamber 152; and a
pressure P12 represents the pressure at the conduit 158. The
following comparative relationships exist between the different
pressures P:
P10<P11 and P12 (4)
[0036] In operation, the supply of spheres 72 and powder 76 are
introduced into the opening 144, opposite to the end 160. When the
spheres 72 and powder 76 enter the separation chamber 152, they
contact the slot 156 and are propelled towards the opening 162 at
the end 160.
[0037] The slot 156 is small enough so that a sphere 72 cannot fall
into the reservoir 154, but the powder 76 can. The pressure P10 and
the dry inert air help to draw the powder 76 through the slot 156.
In some embodiments, the pressure P12 from the conduit 130 may be
high to prevent any of the powder 76 from entering the conduit. It
is noted that the reservoir 154 is physically isolated from the
interior of the conduit 158 so that none of the powder 76 can enter
the conduit. The reservoir 154 drains the powder 76 through the
outlet 148.
[0038] It is understood that several variations may be made in the
foregoing. For example, different heating steps may be used in
different parts of the system 10. Other modifications, changes and
substitutions are also intended in the foregoing disclosure and in
some instances some features of the invention will be employed
without a corresponding use of other features. Accordingly, it is
appropriate that the invention be construed broadly.
* * * * *