Patent Application
20200350188
This disclosure relates generally to the field of substrate processing, such as thin-film coating of substrates.
Vacuum processing of substrates is well known in the art, and referred to sometimes as thin-film processing. When depositing thick films by PVD or performing other vacuum processes, such as ion etching, the substrate temperature can become a difficult problem to solve. In vacuum it is relatively easy to heat substrates, but difficult to cool them. This is especially the case for bi-facial substrates, when neither surface of the substrate may contact any part of the system, such as a chuck. However, allowing sufficient time for the substrates to cool or adding a chamber for cooling substrates will cause a significant drop in system productivity.
A need exists in the art for improved system architecture, which can be used for vacuum processing and provide for efficient cooling of the substrates. Moreover, there's a need in the art for machinery that can form the thin-film processing at commercially acceptable throughput and cost.
The following summary of the disclosure is included in order to provide a basic understanding of some aspects and features of the invention. This summary is not an extensive overview of the invention and as such it is not intended to particularly identify key or critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented below.
Disclosed embodiments provide a novel high productivity inline system which provides chambers for cooling substrates at high throughputs.
In the disclosed embodiments a carrier base vacuum processing system is provided. The system utilizes four carriers; two are in the system being alternately processed one at a time, while two are in atmosphere being unloaded and then reloaded with fresh substrates. A vacuum processing chamber is at the center of the system, and has two openings at opposing walls thereof. A buffer chamber is attached to each side of the processing chamber, such that carriers can be exchanged with the processing chamber via the opening. A cooling module is attached to each of the buffer chambers, wherein one of the cooling modules also serves as a load lock to transport carriers out of and into the vacuum environment.
In disclosed embodiments, four carriers are used: two in atmosphere and two in the vacuum environment. The two that are in atmosphere are being loaded with fresh substrates. The two that are in vacuum environment, one carrier is being cooled while one carrier is being processed. This allows for a high duty cycle for the processing chambers which allows the system to maintain high throughput.
The first loadlock chamber serves two purposes: one it is an atmosphere to vacuum load lock and it is also a vacuum isolated cooling chamber for the second of two carriers. The second chamber is an atmosphere to vacuum load lock for the first of two carriers and a reverse buffer for the first carrier. The second to last chamber is a reverse buffer for the second carrier. The last chamber is a vacuum isolated cooling chamber for the first carrier. The reverse buffer provides sufficient space for the carrier to clear the processing zone of the processing chamber, and then reverse its transport direction and reenter the processing zone.
A benefit of using isolated cooling chambers is that during cooling the pressure in the cooling chamber can be increased to enable better heat conduction. The pressure is advantageously increased by flowing into the isolated cooling chamber the same gas as used for the deposition process. In this manner process contamination upon opening the isolated chamber is avoided. In disclosed embodiments it is not necessary to elevate the pressure to atmospheric pressure, but rather it is sufficient to raise the pressure to sub-atmospheric pressure higher than the vacuum pressure level in the processing chamber. Prior to opening the isolation valve the cooling chamber may be pumped out and when the pressure inside the cooling chamber reaches near equilibrium with the processing chamber the isolation valve may be opened.
Disclosed aspects include a substrate processing system, comprising: a vacuum processing chamber having a first opening on a first wall and a second opening at a second wall opposite the first wall, and a valve gate on the first opening; a front buffer module having an attachment wall attached to the first wall of the processing chamber and having an opening on the attachment wall and a valve gate on an entrance wall opposite the attachment wall; a loadlock chamber having cooling plates therein, the loadlock chamber being attached to the entrance wall of the front buffer module, and having a valve gate positioned on exterior wall; a rear buffer module attached to the second wall of the processing chamber and having an opening matching the second opening on a first side thereof and a valve gate on a second side thereof, opposite the first side; a cooling module having cooling plates therein and attached to the second side of the rear buffer module; a linear track traversing the loadlock chamber, the front buffer chamber, the processing chamber, the rear buffer module and the cooling module; and two substrate carriers linearly traveling on the linear track such that at any given time only one of the carriers may be in one of the loadlock chamber, the front buffer chamber, the processing chamber, the rear buffer module and the cooling module, and the other carrier is at a different one of the loadlock chamber, the front buffer chamber, the processing chamber, the rear buffer module and the cooling module.
Disclosed aspects also include substrate processing system, comprising: a vacuum processing chamber having a first valve gate on a first wall and a second valve gate on a second wall opposite the first wall, the processing chamber having a processing zone commencing at the first wall and a buffer zone terminating at the second wall, the buffer zone being sufficiently large to enable a carrier to completely clear the processing zone such that when the carrier is in the buffer zone no processing is performed on a substrate mounted on the carrier; a front buffer module having an attachment wall attached to the first wall of the processing chamber and having an opening on the attachment wall and a valve gate on an entrance wall opposite the attachment wall; a loadlock chamber having cooling plates therein, the loadlock chamber being attached to the entrance wall of the front buffer module, and having a valve gate positioned on exterior wall; a cooling module having cooling plates therein and attached to the second wall of the processing chamber; a linear track traversing the loadlock chamber, the front buffer chamber, the processing chamber, the rear buffer zone and the cooling module; and two substrate carriers linearly traveling on the linear track such that at any given time one of the carriers may be in one of the loadlock chamber, the front buffer chamber, the processing chamber, the rear buffer module and the cooling module, and the other carrier is at a different one of the loadlock chamber, the front buffer chamber, the processing chamber, the rear buffer module and the cooling module.
Disclosed aspects further include a linear substrate processing system, comprising: a processing module having at least one sputtering source; a first buffer module positioned on a first side of the processing module; a second buffer module positioned on a second side of the processing module directly opposite the first side; a first cooling module attached to the first buffer module; a second cooling module attached to the second buffer module; a transport system transporting substrate carriers in a straight line through the first cooling module, the first buffer module, the processing module, the second buffer module and the second cooling module; wherein the system is arranged linearly in the order: first cooling module, the first buffer module, the processing module, the second buffer module and the second cooling module.
Yet further disclosed aspects include a method for processing substrates in a vacuum processing system, comprising: loading substrates onto a first and a second carriers for processing; loading the first and second carriers into the vacuum system and drawing vacuum within the system; isolating the first carrier inside a cooling chamber and at the same time transporting the second carrier in a linear fashion through a processing zone back and forth for a predetermined number of cycles, and thereafter isolating the second carrier inside a cooling chamber and at the same time transporting the first carrier in a linear fashion through a processing zone back and forth for a predetermined number of cycles. During the steps of isolating the first carrier inside a cooling chamber and isolating the second carrier inside a cooling chamber the method further includes raising the pressure inside the cooling chamber. Raising the pressure inside the cooling chamber may be done by flowing processing gas into the cooling chamber.
Other aspects and features of the invention would be apparent from the detailed description, which is made with reference to the following drawings. It should be appreciated that the detailed description and the drawings provides various non-limiting examples of various embodiments of the invention, which is defined by the appended claims.
The accompanying drawings, which are incorporated in and constitute a part of this specification, exemplify the embodiments of the present invention and, together with the description, serve to explain and illustrate principles of the invention. The drawings are intended to illustrate major features of the exemplary embodiments in a diagrammatic manner. The drawings are not intended to depict every feature of actual embodiments nor relative dimensions of the depicted elements, and are not drawn to scale.
Embodiments of the inventive system and method for fabricating thin-film coating and its wafer loading system will now be described with reference to the drawings. Different embodiments or their combinations may be used for different applications or to achieve different benefits. Depending on the outcome sought to be achieved, different features disclosed herein may be utilized partially or to their fullest, alone or in combination with other features, balancing advantages with requirements and constraints. Therefore, certain benefits will be highlighted with reference to different embodiments, but are not limited to the disclosed embodiments. That is, the features disclosed herein are not limited to the embodiment within which they are described, but may be “mixed and matched” with other features and incorporated in other embodiments.
Disclosed embodiments may be implemented using one or more processing chambers. The system includes a linear transport track, such that carriers within the system cannot share the same space simultaneously, and may only move in a single linear direction back and forth. The system may be tailored such that when one carrier is processing a substrate, the other carrier is isolated in a cooling module to cool the substrate. The substrates may be made of semiconducting material, glass, etc., and may be processed on one or both surfaces. The processing may include etching material from the substrate, depositing material on the substrate, or both.
Benefits of the disclosed embodiments may be highlighted when the processing is performed in a pass-by mode, wherein the processing module is activated continuously while the substrate is passed in front of the processing module to thereby either remove or deposit material on the substrate. In such an arrangement, the carrier must have sufficient travel space so as to clear the substrate from the processing zone of the processing module. Otherwise the processing would not be uniform across the surface of the substrate. Hence, buffer chambers are included, wherein no processing is performed on the surface of the substrate.
Processing chamber 100 has two transport windows, through which carriers can pass: one illustrated on the left side and one on the right side. The window on the left side has a valve gate, identified as gate c, which leads into the front buffer module 115, while the window on the right remain open at all times and leads into the rear buffer module 120. In this particular example, both buffer modules 115 and 120 are empty chambers, except for the linear track traversing through them.
The carriers enter and exit the vacuum environment of the system via loadlock chamber 125. Loadlock chamber 125 is fitted with cooling plates 130, which may include a chiller 132 circulating cooling fluid therein, e.g. liquid nitrogen. Similarly, cooling module 135 has cooling plates 140 therein, which may be connected to chiller 142. The cooling plates may be stationary or movable, and when cooling a substrate they are placed in close proximity to the substrate so as to remove heat from the substrate. In essence, the cooling plates operate as heat sinks, and the heat is removed by the chillers.
In the embodiment of
As illustrated in
The operation of the system is controlled by controller 160, which incorporates a program therein that, when executed causes the system to perform the operations as follows. Starting from a position wherein carrier exchange station 155 has two carriers loaded with fresh substrates and two carriers with processed substrates, platform 157 is moved to align a segment 159 having a carrier with fresh substrate with the linear track 105. Gate valve A is opened and the carrier, call it carrier i, is moved into loadlock 125. Gate valve B is opened and carrier i is moved into front buffer 115. The platform 157 is moved to align the second carrier with fresh substrate, call it carrier j, and carrier j is moved into loadlock 125. Gate valve A is closed and vacuum is drawn from loadlock 125 and front buffer 115. Meanwhile, carrier exchange station 155 and substrate loading station 150 are operated to remove the processed substrates from the two remaining carriers, call them k and l, loading fresh substrates, onto carriers k and l, and return carriers k and l onto the carrier exchange station 155.
Once vacuum level is achieved within loadlock 125 and front buffer 115, gate valve B is closed and gate valve C is opened. In this position, carrier j is isolated within loadlock 125, while carrier i has free passage among front buffer 115, process module 100 and rear buffer 120. Thus, carrier i may move back and forth on the linear track 105, each time passing through the processing chamber 100, thereby performing a pass-by processing, e.g., thin film deposition on the substrate loaded onto carrier i. The process is performed while flowing processing gas from gas supply 131 into the processing module 100. Once the programmed number of passes has been completed, gate valve D is opened and carrier i is moved into cooling module 135 (sometimes referred to as rear cooling module) and gate valve D is closed. Cooling plates 140 are activated to cool the substrate loaded onto carrier i. Also, optionally processing gas is flowed to the cooling module 135 to elevate the pressure within the cooling chamber, thereby enhancing heat conduction from the substrate to the cooling plates. The pressure maintained within the isolated cooling module may be sub-atmospheric, but higher than the pressure within processing module 100.
Gate valve B is now opened and carrier j is moved into front buffer 115 and then gate valve B is closed. Now, while carrier i is isolated within cooling module 135, carrier j has free passage among front buffer 115, process module 100 and rear buffer 120. Thus, carrier j may move back and forth on the linear track 105, each time passing through the processing chamber 100, thereby performing a pass-by processing, e.g., thin film deposition on the substrate loaded onto carrier j. Once the programmed number of passes has been completed, gate valve B is opened and carrier j is moved into loadlock 125 and gate valve B is closed. Cooling plate 130 now cool the substrate loaded onto carrier j. Also, optionally processing gas is flowed to the loadlock 125 to elevate the pressure within the cooling chamber, thereby enhancing heat conduction from the substrate to the cooling plates. The pressure maintained within the isolated loadlock 125 may be sub-atmospheric, but higher than the pressure within processing module 100.
Next, gate valve D is opened and carrier i is moved into rear buffer 120 and gate valve D is closed. In this position, there are two options. If further processing is required, then while carrier j is isolated within loadlock 125, carrier i may move back and forth on the linear track 105, each time passing through the processing chamber 100, thereby performing further pass-by processing, e.g., thin film deposition on the substrate loaded onto carrier i. Once the programmed number of passes has been completed, gate valve D is opened and carrier i is moved into cooling module 135 and gate valve D is closed. The processing of carrier j may now commence.
On the other hand, if no further processing was required, then carrier i is moved into front buffer 115 and gate valve C is closed. Gate valve B is opened and loadlock 125 and front buffer 115 are brought to atmospheric pressure. Gate valve A may then be opened and carriers i and j moved onto platform 157. The entire process may then repeat for carriers k and l.
Thus, during processing a first carrier is isolated in a first cooling chamber while a second carrier is moved linearly back and forth from a first buffer station, through a processing chamber and to a second buffer station, as many times as programmed. Once processing is completed the second carrier is moved into a second cooling chamber and the first carrier is moved linearly back and forth from the first buffer station, through the processing chamber and to the second buffer station, as many times as programmed. This entire process is repeated as many cycles as needed.
Substrate support arms 214 are attached to the base 208, leading to frame 216. Frame 216 includes clips 206 which support the substrate at peripheral circumference thereof. This enables double sided processing without contacting either surface of the substrate. The support arms 214 and frame 216 are made as thin as possible, thereby enabling placing the cooling plates 130 and 140 very close to the substrate to efficiently remove heat from the substrate.
As shown in
While the example illustrated in
The rear buffer 120 need not be a separate chamber, but may rather be part of the processing chamber 100. An example is illustrated in
In step 600 the first carrier is loaded into the front buffer chamber and in 602 the second carrier is loaded into the loadlock (also the first cooling chamber). At 604 the gate valve of the loadlock is closed and at 606 the loadlock and the front buffer chambers are pumped to vacuum level. Notably, as can be appreciated from the entirety of the disclosure herein, each of the loadlock and front buffer performs two functions. The loadlock chamber also forms a front cooling chamber, while the front buffer also functions as a secondary loadlock chamber, as it also cycles between atmospheric and vacuum pressure levels.
Once vacuum level has been reached, at 608 the process chamber valve gate (gate C in
Once the number of cycles has been completed for the first carrier, at 612 the gate valve to the rear cooling module is opened, at 614 the first carrier is moved into the rear cooling module, and at 616 the gate valve to the rear cooling module is closed. Optionally, at this time gas is pumped into the rear cooling module. At 618 the gate valve of the front buffer is opened (valve B in
That is, in 624 the second carrier is cycled through the front buffer, processing chamber and rear buffer, back and forth, for a programmed number of times. At the end of this process of the second carrier, at 626 the gate valve for the front buffer is opened, and at 628 the second carrier is transferred into the loadlock. Optionally, at this time gas is pumped into the loadlock. At 630 it is determined whether processing on these two carriers is completed, or whether further processing is required. This can be simply by checking how many cycles each carrier has been processed. For example, for a deposition process the thickness of the deposited layer at each pass of the substrate is known, e.g., by measurement performed beforehand. The total required thickness is also known. So, from that one can derive the number of cycles each substrate must pass in front of the deposition module. However, when it is determined that after a certain number of passes the substrate's temperature rise is too high, the total number of required cycles can be divided into several periods of cycles, wherein after each period the carrier is transferred into a cooling module while the other carrier is processed.
When at 630 it is determined that further processing is required, if gas was pumped into the rear cooling module, the gas is pumped out to bring the pressure level of the rear cooling module to the same pressure as the processing module, or slightly above that level. At 632 the gate valve for the rear cooling module is opened, at 634 the first carrier is transferred into the rear buffer, and at 636 the gate valve of the rear cooling chamber is closed. The process now reverts to step 610 and repeats all the steps until it arrives at step 630 again.
When in step 630 it is determined that processing of both carriers has been completed, the process proceeds to step 638, wherein the gate valve of the rear cooling chamber is opened, at 640 the first carrier is transported to the front buffer and at 642 the gate valve of the rear cooling chamber is closed. At 644 the gate valve of the process chamber is closed. At 646 the front buffer and the loadlock are pumped back to atmospheric pressure. At 648 the gate valve of the loadlock is opened and at 650 the first and second carriers can be removed from the chamber and be reloaded with fresh substrate for processing. In the embodiment of
In disclosed embodiments, optionally when a carrier is isolated in a cooling chamber the pressure in the cooling chamber can be elevated to a sub-atmospheric pressure that will add a level of conductive cooling and greatly accelerate the cooling. The pressure should be determined to reach such level that it can be pumped back down to the process chambers operating vacuum before opening the isolation valve and processing the carrier. The gas used to increase the cooling rate may be the same gas or gases that the process module is using. The crossover point when the isolation slot valve opens would be when the pressure between cooling chamber and process chamber are at near equilibrium such that the opening of the isolation slot valve would not adversely affect the process.
It should be understood that processes and techniques described herein are not inherently related to any particular apparatus and may be implemented by any suitable combination of components. Further, various types of general purpose devices may be used in accordance with the teachings described herein. The present invention has been described in relation to particular examples, which are intended in all respects to be illustrative rather than restrictive. Those skilled in the art will appreciate that many different combinations will be suitable for practicing the present invention.
Moreover, other implementations of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. Various aspects and/or components of the described embodiments may be used singly or in any combination. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
This application claims priority benefit from U.S. Provisional Application 62/842,376, filed on May 2, 2019, the entire disclosure of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62842376 | May 2019 | US |
