Patent Application
20200109473
The present application relates to material deposition technologies, and more specifically to high throughput deposition apparatus.
Vacuum depositions such as sputtering, chemical vapor deposition (CVD), or plasma enhanced chemical vapor deposition (PECVD) are used in many industries to deposit materials on workpieces such as web, glass, semiconductor wafers, hard disks, et al.
For material depositions on rectangular shaped workpieces and webs, PECVD is often applied between parallel plates to achieve good uniformity. One challenge for parallel-plate PECVD is the relative low plasma density and low densities of reactive species, which require relatively high process pressures to maintain stable plasma. The higher process pressure leads to low ionization efficiency and high rate of reactions in gas phase, resulting in low material utilization, powder formation and expensive waste gas treatment system. Another challenge for PECVD is deposition on the plasma sources, which can lead to particulates formation, clogging of gas distribution holes, and change in plasma conditions. The in-situ cleaning of the plasma sources not only takes time, but is also impractical for some applications such as roll-to-roll web processing where the workpieces are always present.
In vacuum depositions, it is desirable to have small source-to-workpiece area ratios to minimize wasted deposition on deposition sources. To increase productivity, it is also desirable to have multiple workpiece processed at same time. For web processing, it is desirable to have minimum contact with web handling equipment, such as rollers. For some applications, multiple processing steps are carried out in the same system, the earlier processing step can produce an intermediate deposited microstructure, which are strengthened by depositing thick films in later depositing steps. Any physical contact with the workpieces before the entire process is complete is detrimental to the workpieces.
There is therefore a need for PECVD system with high gas utilization, reduced gas phase reactions and powder formations, reduced deposition on deposition sources, increased lifetime of deposition sources, and increased system productivity.
The present application discloses a high throughput deposition source and system for PECVD. Comparing to conventional systems, the disclosed source and system have higher gas utilization, reduced gas phase reactions and powder formations, reduced deposition on deposition sources, increased lifetime of deposition sources, minimized the process condition variation throughout source life time, reduced waste treatment, increased system productivity, and can eliminate physical contacts between workpieces and deposition system during processing.
In one general aspect, the present invention relates to a high throughput deposition apparatus that includes a vacuum chamber comprising a first processing chamber, a plurality of elongated deposition sources in parallel in the first processing chamber, wherein each of the elongated deposition sources can include a gas distribution channel configured to provide a deposition material in a gas form, and an electrode that can generate a plasma in the deposition material, and a web transport mechanism that can move a plurality of workpiece webs passing by the elongated deposition sources in the first processing chamber, wherein the plurality of workpiece webs can be parallel to each other and are configured to receive the deposition material in the first process chamber.
Implementations of the system may include one or more of the following. The web transport mechanism can include unwind reels and rollers configured to feed the plurality of workpiece webs, and rewind reels and rollers configured to redirect the plurality of workpiece webs. The high throughput deposition apparatus can further include: a first compartment configured to house the unwind reels and rollers; and a second compartment configured to house rewind reels and rollers. The plurality of workpiece webs can be only in contact with the unwind reels and rollers and the rewind reels and rollers. The elongated deposition sources can be plasma sources. At least one of the elongated deposition sources further comprises one or more magnets configured to confine the plasma. The elongated deposition sources can be substantially parallel to each other. The plurality of workpiece webs can be moved by the transport mechanism in a substantially vertical direction. The vacuum chamber can further include a second processing chamber and a second deposition source in the second processing chamber, wherein the web transport mechanism can further move the plurality of workpiece webs through the second processing chamber, wherein the plurality of workpiece web are configured to receive a second deposition material from the second deposition source in the second process chamber. The high throughput deposition apparatus can further include a first differential pumping chamber between the first processing chamber and the second processing chamber, wherein the web transport mechanism can further move the plurality of workpiece webs through the first differential pumping chamber. The vacuum chamber can further include a third processing chamber; and a second differential pumping chamber between the first processing chamber and the second processing chamber, wherein the web transport mechanism can further move the plurality of workpiece webs through the third processing chamber and the second differential pumping chamber.
In another general aspect, the present invention relates to a plasmas source that includes an elongated electrode that can be electrically biased at a first polarity; a gas distribution channel within the elongated electrode, the gas distribution channel that can provide a gas material, wherein a receiver is configured to be electrically biased at a second polarity thereby generating a plasma in the gas material; and one or more magnets that can confine the plasma, wherein the receiver is configured to receive material deposition from the plasma.
Implementations of the system may include one or more of the following. The plasmas source can further include a cooling channel in the elongated electrode, the cooling channel configured transport a cooling fluid to lower temperature of the elongated electrode. The gas distribution channel can be at least partially positioned inside the elongated electrode. The one or more magnets can be positioned inside the elongated electrode. The one or more magnets can be magnetized in along dimension of the elongated electrode.
In another general aspect, the present invention relates to a plasmas source that includes an elongated electrode that can be electrically biased at a first polarity, a gas distribution channel within the elongated electrode, the gas distribution channel that can provide a gas material, wherein a receiver is configured to be electrically biased at a second polarity thereby generating a plasma in the gas material, one or more magnets that can confine the plasma, wherein the receiver is configured to receive material deposition from the plasma, and a transport mechanism that can move a protective web over at least a portion of the elongated electrode, wherein the protective web can receive material deposition from the plasma and to prevent material deposition on the elongated electrode.
Implementations of the system may include one or more of the following. The transport mechanism can include a first reel configured to provide a new protective web and a second reel that can take up a protective web deposited with the deposition material. The transport mechanism can include a roller configured to turn around the protective web at an end of the elongated electrode. The plasmas source can further include a cooling channel in the elongated electrode. The cooling channel can transport a cooling fluid to lower temperature of the elongated electrode. The one or more magnets can be positioned inside the elongated electrode. The one or more magnets can be magnetized in along dimension of the elongated electrode.
These and other aspects, their implementations and other features are described in details in the drawings, the description and the claims.
In operation, a voltage such as radio frequency (RF) power is applied between workpieces and the electrode and a plasma is formed with aid of the back filled gases. Unlike conventional parallel-plate PECVD sources which includes a pair of counter electrodes (a cathode and an anode), the disclosed plasma source 100 only includes an electrode with one polarity (a cathode or an anode); there is no dedicated counter electrode. Instead, the one or more workpieces 120 are electrically biased relative to the electrode 110 to perform the function of a counter electrode. The one or more workpieces 120 are configured to receive material depositions. In some cases, such as the web are electrically insulators or the deposited films are thick insulators, or to optimize plasma density, separate counter electrodes can be placed near electrode 110 to form plasma.
The electrode 110 can be made of two electrode pieces 111, 112 each including its own liquid cooling channel 130 welded in and with its own gas distribution channel. Two electrode pieces 111, 112 can be bolted together and attached to a mounting flange 140 with screws and bolts. O-ring seals can be used to ensure the vacuum integrity in the vacuum chamber (not shown). The mounting flange 140 can be made of insulating materials such as TEFLON or PEEK to ensure electrical isolations of the electrode 110 from the vacuum chamber (not shown) and the workpieces 120. In one implementation, the mounting flange 140 can be mounted to the vacuum chamber (not shown) of the vacuum deposition system 10.
The cooling channels 130 in the electrode pieces 111, 112 can be connected through a cooling channel interface 135 with O-ring seal as seen in the cross-sectional view of
In operation, a voltage such as radio frequency (RF) power is applied between workpieces 120 and the electrode 110. In PECVD, a plasma is formed with aid of the back filled gases. The plasma breaks up the gases in the vacuum chamber (not shown) and deposit materials on the workpieces 120. In some embodiments, in case of plasma etch or cleaning, the plasma breaks up the gases to etch the workpieces 120 and the electrode 110 in the vacuum chamber (not shown). The operation pressure in the vacuum chamber (not shown) can be kept between tens of Millitorr to tens of Torrs when radio frequency (RF) power is applied between the electrode 110 and the workpieces 120.
The disclosed plasma source has the advantage of having small electrode areas to maximize deposition on workpieces, simple design, and can process multiple workpieces at same time. The presently disclosed plasma source also allows easy cleaning of the electrode and channels and holes for gas distribution.
In some embodiments, referring to
Referring to
In PECVD, materials are deposited on all surfaces that are exposed to plasma. The disclosed vacuum deposition system 10 minimizes the surface area of the electrode 110 and maximizes the percentage of deposition on the workpieces 120 to increase material utilization. However, thick materials can still be deposited on the deposition sources over time. Thick material deposition on the electrode 110 can lead to particulate formation, flaking off of the deposited materials, a change of plasma conditions over time, and clogging of the gas distribution holes 185. Plasma cleaning can be used to reduce these effects, but may not be practical in some cases such as a web formed workpieces, which has a portion always exposed to plasma.
In some embodiments, as shown in
The two storage reels are driven by one or two separate motors 340 outside the mounting flange 140 through a rotational vacuum feed through and a set of angular gears 345 in this embodiment. Other means of rotating the storage reels are also possible. The new web reels 330 can be attached to active or passive tension devices such as slippage clutch or motors to control the tension of the protective webs 310. With aid of at least two turn around rollers 335 and guiding rollers 350, the protect webs 310 can cover all 4 surfaces of the electrode.
Referring to
Referring to
In some embodiments, referring to
The un-wind reels and rollers 460 in the upper compartment and the process chamber 455 are separated by separation plates 468. The process chamber 455 below the unwind rollers include a thermal CVD zone including heaters 458. The process chamber 456 can include a PECVD process zone. The process chamber 455 and the process chamber 456 are separated by separation plates 470 and one or more differential pumping chambers 472 (hidden from view). The process chamber 456 and the process chamber 457 are separated by separation plates 480 and one or more differential pumping chambers 482. The process chamber 457 and the re-wind reels and rollers 465 in the lower compartment are separated by separation plates 490. The separation plates 468 and 480 are mainly used to cool the upper and lower compartment to prevent deposition and do not create significant pressure differentials.
One advantage of the disclosed vacuum process systems is that there is no physical contact between the deposition surfaces of the workpieces and the components in the deposition system through the processing steps. The webs of workpieces 420 are only in contact with the un-wind reels and rollers 460 and the re-wind reels and rollers 465. The webs of workpieces can be substantially vertically aligned so they are free of gravity-caused deformation. The web transport mechanism can thus be simplified without the need for rollers to support the web in the process steps.
In some embodiments,
The webs are heated by heaters 458 to desired temperature. A series of gas distribution lines 185 flow gases into the first process chamber 455 in a uniform fashion. Optionally, gas distribution channels can be machined or/and welded in the top shelf plate 462. The top shelf plate 462, the separation plates 470, 480, 490, and the vacuum chamber 452 can be cooled so that the top un-wind reels and rollers 460 and bottom re-wind reels and rollers 465 are at low temperature to avoid deposition.
Multiple sheet metals can be mounted to the vacuum chamber 452 and the separation plates 470, 480, 490 to reduce heat loss and keep the vacuum chamber 452 and the separation plates 470, 480, 490 cool.
The first process chamber 455 can have its own pumping ports, or be pumped by the pumps in the differential pump chamber through the slits in the first separation plate. The differential pump chamber is a box with slits on top and bottom to allow the webs of workpieces 420 to go through. The box can have a removable side cover to allow cleaning and service. There are optional plates inside the differential pumping box with slits to allow the webs of workpieces 420 to go through and separate the box into multiple differential pumping chambers, each with its own set of pumps, to further isolate the first process chamber and the second processing chamber (e.g. PECVD).
Once the webs of workpieces 420 enter a PECVD process chamber (e.g. the process chamber 456), the deposition sources form plasma with the voltage biased webs of workpieces 420 as described above in discussion with
After PECVD deposition, the webs of workpieces 420 can enter optional or additional process chambers. There may be one or more differential pumping chambers 455-457 to isolate the process chambers 455-457. After all processes are finished, the webs may be wound to re-wind reels and rollers 465 through idler rollers 510 in a lower compartment. Referring to
In case of a rectangular-shaped vacuum envelope (or chamber), the webs of workpieces at the end of the array may only see deposition on one side during PECVD, if there is no deposition source at outer side of the workpiece web array, as shown in
The arrays of deposition sources and webs can be doubled by placing identical arrays on the opposite side of the vacuum envelope. In some case, arrays of deposition sources can be installed on a third wall or even a fourth wall of the vacuum chamber. The vacuum chamber can be shaped like polygon with more than 4 sides.
Only a few examples and implementations are described. Other implementations, variations, modifications and enhancements to the described examples and implementations may be made without deviating from the spirit of the present invention. For example, the disclosed deposition apparatus are compatible with other spatial configurations for the substrate, the deposition source, and substrate movement directions than the examples provided above. The PECVD sources can be of different types and configurations for the system.
| Number | Date | Country | |
|---|---|---|---|
| 62742822 | Oct 2018 | US |
