Patent Application
20120225192
Embodiments of the invention generally relate to an apparatus and a method for depositing materials. More specifically, embodiments of the invention are directed to a atomic layer deposition chambers with linear reciprocal motion.
In the field of semiconductor processing, flat-panel display processing or other electronic device processing, vapor deposition processes have played an important role in depositing materials on substrates. As the geometries of electronic devices continue to shrink and the density of devices continues to increase, the size and aspect ratio of the features are becoming more aggressive, e.g., feature sizes of 0.07 μm and aspect ratios of 10 or greater. Accordingly, conformal deposition of materials to form these devices is becoming increasingly important.
During an atomic layer deposition (ALD) process, reactant gases are introduced into a process chamber containing a substrate. Generally, a first reactant is introduced into a process chamber and is adsorbed onto the substrate surface. A second reactant is introduced into the process chamber and reacts with the first reactant to form a deposited material. A purge step may be carried out to ensure that the only reactions that occur are on the substrate surface. The purge step may be a continuous purge with a carrier gas or a pulse purge between the delivery of the reactant gases.
There is an ongoing need in the art for improved apparatuses and methods for processing substrates by atomic layer deposition.
Embodiments of the invention are directed to atomic layer deposition systems comprising a processing chamber. A gas distribution plate is in the processing chamber. The gas distribution plate comprises at least one gas injector unit. Each gas injector unit comprises a plurality of elongate gas injectors including at least two first reactive gas injectors in fluid communication with a first reactive gas and at least one second reactive gas injector in fluid communication with a second reactive gas different from the first reactive gas. The at least two first reactive gas injectors surrounding the at least one second reactive gas injector. A substrate carrier is configured to move a substrate reciprocally with respect to the gas injector unit in a back and forth motion perpendicular to an axis of the elongate gas injectors. In specific embodiments, the substrate carrier is configured to rotate the substrate.
In detailed embodiments, the plurality of gas injectors further comprises at least one third gas injector, the at least two first gas injectors surrounding the at least one third gas injector.
In some embodiments, the at least one gas injector unit further comprises at least two purge gas injectors, each of the purge gas injectors between the at least one first gas injector and the at least one second gas injector. In detailed embodiments, the at least one gas injector unit further comprises at least four vacuum ports, each of the vacuum ports disposed between each of the at least one first reactive gas injector, the at least one second reactive gas injector and the at least two purge gas injectors.
In some embodiments, the gas distribution plate has one gas injector unit. The gas injector unit consists essentially of, in order, a leading first reactive gas injector, a second reactive gas injector and a trailing first reactive gas injector. In detailed embodiments, the gas distribution plate further comprises a purge gas injector between the leading first reactive gas injector and the second reactive gas injector, and a purge gas injector between the second reactive gas injector and the trailing first reactive gas injector, each purge gas injector separated from the reactive gas injectors by a vacuum. In specific embodiments, the gas distribution plate further comprises, in order, a vacuum port, a purge gas injector and another vacuum port before the leading first reactive gas injector and after the second first reactive gas injector. In particular embodiments, the gas distribution plate further comprises a first vacuum channel and a second vacuum channel, the first vacuum channel in flow communication with vacuum ports adjacent the first reactive gas injectors and the second vacuum channel in flow communication with vacuum ports adjacent the second reactive gas injector.
In some embodiments, the at least one gas injector unit further comprises at least two vacuum ports disposed between the at least one first reactive gas injector and the at least one second reactive gas injector.
In one or more embodiments, the substrate carrier is configured to transport the substrate from a region in front of the gas distribution plate to a region after the gas distribution plate so that the entire substrate surface passes through a region occupied by the gas distribution plate.
According to some embodiments, there are in the range of 2 to 24 gas injectors units. In detailed embodiments, each of the gas injectors consists essentially of, in order, a leading first reactive gas injector, a second reactive gas injector, and a trailing first reactive gas injector. In specific embodiments, the system further comprises a substrate carrier configured to carry a substrate and to move, during processing, in a linear reciprocal path between a first extent and second extent, wherein a distance between the first extent and the second extent is about equal to a length of the substrate divided by the number of gas injector units. In particular embodiments, the substrate carrier is configured to carry the substrate outside of the first extent to a loading position.
Additional embodiments of the invention are directed to atomic layer deposition systems comprising a processing chamber. A gas distribution plate is in the processing chamber. The gas distribution plate comprises a plurality of gas injectors. The plurality of gas injectors consists essentially of, in order, a vacuum port, a purge gas injector in flow communication with a purge gas, a vacuum port, a first reactive gas injector in flow communication with a first reactive gas, a vacuum port, a purge gas injector in flow communication with the purge gas, a vacuum port, a second reactive gas injector in flow communication with a second reactive gas different from the first reactive gas, a vacuum port, a purge gas injector in flow communication with the purge gas, a vacuum port, a first reactive gas injector in flow communication with the first reactive gas, a vacuum port, a purge gas injector in flow communication with the purge gas and a vacuum port. A substrate carrier is configured to move a substrate reciprocally with respect to the gas distribution plate in a back and forth motion along an axis perpendicular to an axis of the elongate gas injectors.
Further embodiments of the invention are directed to methods of processing a substrate. A portion of a substrate is passed across a gas injector unit in a first direction so that the portion of the substrate is exposed to, in order, a leading first reactive gas stream, a second reactive gas stream different from the first reactive gas stream and a trailing first reactive gas stream to deposit a first layer. The portion of the substrate I passed across the gas injector unit in a second gas direction opposite of the first direction so that the portion of the substrate is exposed to, in order, the trailing first reactive gas stream, the second reactive gas stream and the leading first reactive gas stream to create a second layer.
In some embodiments, the portion of the substrate is further exposed to a purge gas stream between each of the first reactive gas streams and the second reactive gas streams. In detailed embodiments, passing the portion of the substrate in a first direction exposes the portion of the substrate to, in order, a leading first reactive gas stream, a leading second reactive gas stream, a first intermediate first reactive gas stream, a third reactive gas stream, a second intermediate first reactive gas stream, a trailing second reactive gas stream and a trailing first reactive gas stream, and passing the portion of the substrate in the second direction exposes the portion of the substrate to the gas streams in reverse order. In specific embodiments, the substrate is divided into a plurality of portions in the range of about 2 to about 24, and each individual portion is exposed to the gas streams substantially simultaneously.
So that the manner in which the above recited features of the invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
Embodiments of the invention are directed to atomic layer deposition apparatus and methods which provide improved movement of substrates. Specific embodiments of the invention are directed to atomic layer deposition apparatuses (also called cyclical deposition) incorporating a gas distribution plate having a detailed configuration and reciprocal linear motion.
The system 100 includes a gas distribution plate 30 capable of distributing one or more gases across a substrate 60. The gas distribution plate 30 can be any suitable distribution plate known to those skilled in the art, and specific gas distribution plates described should not be taken as limiting the scope of the invention. The output face of the gas distribution plate 30 faces the first surface 61 of the substrate 60.
Substrates for use with the embodiments of the invention can be any suitable substrate. In detailed embodiments, the substrate is a rigid, discrete, generally planar substrate. As used in this specification and the appended claims, the term “discrete” when referring to a substrate means that the substrate has a fixed dimension. The substrate of specific embodiments is a semiconductor wafer, such as a 200 mm or 300 mm diameter silicon wafer.
The gas distribution plate 30 comprises a plurality of gas ports configured to transmit one or more gas streams to the substrate 60 and a plurality of vacuum ports disposed between each gas port and configured to transmit the gas streams out of the processing chamber 20. In the detailed embodiment of
In another aspect, a remote plasma source (not shown) may be connected to the precursor injector 120 and the precursor injector 130 prior to injecting the precursors into the chamber 20. The plasma of reactive species may be generated by applying an electric field to a compound within the remote plasma source. Any power source that is capable of activating the intended compounds may be used. For example, power sources using DC, radio frequency (RF), and microwave (MW) based discharge techniques may be used. If an RF power source is used, it can be either capacitively or inductively coupled. The activation may also be generated by a thermally based technique, a gas breakdown technique, a high intensity light source (e.g., UV energy), or exposure to an x-ray source. Exemplary remote plasma sources are available from vendors such as MKS Instruments, Inc. and Advanced Energy Industries, Inc.
The system 100 further includes a pumping system 150 connected to the processing chamber 20. The pumping system 150 is generally configured to evacuate the gas streams out of the processing chamber 20 through one or more vacuum ports 155. The vacuum ports 155 are disposed between each gas port so as to evacuate the gas streams out of the processing chamber 20 after the gas streams react with the substrate surface and to further limit cross-contamination between the precursors.
The system 100 includes a plurality of partitions 160 disposed on the processing chamber 20 between each port. A lower portion of each partition extends close to the first surface 61 of substrate 60, for example about 0.5 mm from the first surface 61, This distance should be such that the lower portions of the partitions 160 are separated from the substrate surface by a distance sufficient to allow the gas streams to flow around the lower portions toward the vacuum ports 155 after the gas streams react with the substrate surface. Arrows 198 indicate the direction of the gas streams. Since the partitions 160 operate as a physical barrier to the gas streams, they also limit cross-contamination between the precursors. The arrangement shown is merely illustrative and should not be taken as limiting the scope of the invention. It will be understood by those skilled in the art that the gas distribution system shown is merely one possible distribution system and the other types of showerheads and gas distribution systems may be employed.
In operation, a substrate 60 is delivered (e.g., by a robot) to the load lock chamber 10 and is placed on a carrier 65. After the isolation valve 15 is opened, the carrier 65 is moved along the track 70, which may be a rail or frame system. Once the carrier 65 enters in the processing chamber 20, the isolation valve 15 closes, sealing the processing chamber 20. The carrier 65 is then moved through the processing chamber 20 for processing. In one embodiment, the carrier 65 is moved in a linear path through the chamber.
As the substrate 60 moves through the processing chamber 20, the first surface 61 of substrate 60 is repeatedly exposed to the precursor of compound A coming from gas ports 125 and the precursor of compound B coming from gas ports 135, with the purge gas coming from gas ports 145 in between. Injection of the purge gas is designed to remove unreacted material from the previous precursor prior to exposing the substrate surface 110 to the next precursor. After each exposure to the various gas streams (e.g., the precursors or the purge gas), the gas streams are evacuated through the vacuum ports 155 by the pumping system 150. Since a vacuum port may be disposed on both sides of each gas port, the gas streams are evacuated through the vacuum ports 155 on both sides. Thus, the gas streams flow from the respective gas ports vertically downward toward the first surface 61 of the substrate 60, across the first surface 110 and around the lower portions of the partitions 160, and finally upward toward the vacuum ports 155. In this manner, each gas may be uniformly distributed across the substrate surface 110. Arrows 198 indicate the direction of the gas flow. Substrate 60 may also be rotated while being exposed to the various gas streams. Rotation of the substrate may be useful in preventing the formation of strips in the formed layers. Rotation of the substrate can be continuous or in discrete steps.
Sufficient space is generally provided at the end of the processing chamber 20 so as to ensure complete exposure by the last gas port in the processing chamber 20. Once the substrate 60 reaches the end of the processing chamber 20 (i.e., the first surface 61 has completely been exposed to every gas port in the chamber 20), the substrate 60 returns back in a direction toward the load lock chamber 10. As the substrate 60 moves back toward the load lock chamber 10, the substrate surface may be exposed again to the precursor of compound A, the purge gas, and the precursor of compound B, in reverse order from the first exposure.
The extent to which the substrate surface 110 is exposed to each gas may be determined by, for example, the flow rates of each gas coming out of the gas port and the rate of movement of the substrate 60. In one embodiment, the flow rates of each gas are configured so as not to remove adsorbed precursors from the substrate surface 110. The width between each partition, the number of gas ports disposed on the processing chamber 20, and the number of times the substrate is passed back and forth may also determine the extent to which the substrate surface 110 is exposed to the various gases. Consequently, the quantity and quality of a deposited film may be optimized by varying the above-referenced factors.
In another embodiment, the system 100 may include a precursor injector 120 and a precursor injector 130, without a purge gas injector 140. Consequently, as the substrate 60 moves through the processing chamber 20, the substrate surface 110 will be alternately exposed to the precursor of compound A and the precursor of compound B, without being exposed to purge gas in between.
The embodiment shown in
In yet another embodiment, the system 100 may be configured to process a plurality of substrates. In such an embodiment, the system 100 may include a second load lock chamber (disposed at an opposite end of the load lock chamber 10) and a plurality of substrates 60. The substrates 60 may be delivered to the load lock chamber 10 and retrieved from the second load lock chamber.
In one or more embodiments, at least one radiant heat lamps 90 is positioned to heat the second side of the substrate. The radiant heat source is generally positioned on the opposite side of gas distribution plate 30 from the substrate. In these embodiments, the gas cushion plate is made from a material which allows transmission of at least some of the light from the radiant heat source. For example, the gas cushion plate can be made from quartz, allowing radiant energy from a visible light source to pass through the plate and contact the back side of the substrate and cause an increase in the temperature of the substrate.
In some embodiments, the carrier 65 is a susceptor 66 for carrying the substrate 60. Generally, the susceptor 66 is a carrier which helps to form a uniform temperature across the substrate. The susceptor 66 is movable in both directions (left-to-right and right-to-left, relative to the arrangement of
In still another embodiment, the top surface 67 of the susceptor 66 includes a recess 68 configured to accept the substrate 60, as shown in
In some embodiments, the processing chamber 20 includes a substrate carrier 65 which is configured to move a substrate along a linear reciprocal path along an axis perpendicular to the elongate gas injectors. As used in this specification and the appended claims, the term “linear reciprocal path” refers to either a straight or slightly curved path in which the substrate can be moved back and forth. Stated differently, the substrate carrier may be configured to move a substrate reciprocally with respect to the gas injector unit in a back and forth motion perpendicular to the axis of the elongate gas injectors. As shown in
Referring to
Similarly,
In specific embodiments, the gas injector unit 31 consists essentially of, in order, a leading first reactive gas A injector 32a, a second reactive gas B injector 32b and a trailing first reactive gas A injector 32c. As used in this specification and the appended claims, the term “consisting essentially of”, and the like, mean that the gas injector unit 31 excludes additional reactive gas injectors, but does not exclude non-reactive gas injectors like purge gases and vacuum lines. Therefore, in the embodiment shown in
A specific embodiment of the invention is directed to an atomic layer deposition system comprising a processing chamber with a gas distribution plate therein. The gas distribution plate comprises a plurality of gas injectors consisting essentially of, in order, a vacuum port, a purge gas injector, a vacuum port, a first reactive gas injector, a vacuum port, a purge port, a vacuum port, a second reactive gas injector, a vacuum port, a purge port, a vacuum port, a first reactive gas injector, a vacuum port, a purge port and a vacuum port.
In some embodiments, the gas plenums and gas injectors may be connected with a purge gas supply (e.g., nitrogen). This allows the plenums and gas injectors to be purged of residual gases so that the gas configuration can be switched, allowing the B gas to flow from the A plenum and injectors, and vice versa. Additionally, the gas distribution plate 30 may include additional vacuum ports along sides or edges to help control unwanted gas leakage. As the pressure under the injector is about 1 torr greater than the chamber, the additional vacuum ports may help prevent reactive gases leaking into the chamber. In some embodiments, the gas distribution plate 30 also includes one or more heater or cooler.
Additional embodiments of the invention are directed to atomic layer deposition systems comprising a gas distribution plate 30 having more than one gas injector unit 31.
In one embodiment, each individual gas injector units 31 has a sequence of gas injectors in the ABA configuration. In specific embodiments, each of the gas injector units 31 consists essentially of, in order, a leading first reactive gas A injector, a second reactive gas B injector, and a trailing first reactive gas A injector.
In a system such as that shown in
A full stroke (back and forth paths) would result in a full cycle (2 layer) exposure to the substrate. In this short-stroke configuration, the substrate carrier can be configured to move, during processing, in a linear reciprocal path between the first extent and second extent. The substrate 60 is always under the gas distribution plate during processing. The distance between the first extent 97 and the second extent 98 is about equal to a length of the substrate divided by the number of gas injector units. So in the embodiment shown in
In detailed embodiments, the substrate carrier is configured to carry the substrate outside of the first extent 97 to a loading position. In some embodiments, the substrate carrier is configured to carry the substrate outside of the second extent 98 to an unloading position. The loading and unloading positions can be reversed if necessary.
Additional embodiments of the invention are directed to methods of processing a substrate. A portion of a substrate is passed across a gas injector unit in a first direction. As used in this specification and the appended claims, the term “passed across” means that the substrate has been moved over, under, etc., the gas distribution plate so that gases from the gas distribution plate can react with the substrate or layer on the substrate. In moving the substrate in the first direction, the substrate is exposed to, in order, a leading first reactive gas stream, a second reactive gas stream and a trailing first reactive gas stream to deposit a first layer. The portion of the substrate is then passed across the gas injector unit in a direction opposite of the first direction so that the portion of the substrate is exposed to, in order, the trailing first reactive gas stream, the second reactive gas stream and the leading first reactive gas stream to create a second layer. If there is only one gas injector unit, the substrate will be passed beneath the entire relevant portion of the gas distribution plate. Regions of the gas distribution plate outside of the reactive gas injectors is not part of the relevant portion. In embodiments where there is more than one gas injector unit, the substrate will move a portion of the length of the substrate based on the number of gas injector units. Therefore, for every n gas injector units, the substrate will move 1/nth of the total length of the substrate.
In detailed embodiments, the method further comprises exposing the portion of the substrate to a purge gas stream between each of the first reactive gas streams and the second reactive gas streams. The gases of some embodiments are flowing continuously. In some embodiments, the gases are pulsed as the substrate moves beneath the gas distribution plate.
According to one or more embodiments, passing the portion of the substrate in a first direction exposes the portion of the substrate to, in order, a leading first reactive gas stream, a leading second reactive gas stream, a first intermediate first reactive gas stream, a third reactive gas stream, a second intermediate first reactive gas stream, a trailing second reactive gas stream and a trailing first reactive gas stream, and passing the portion of the substrate in the second direction exposes the portion of the substrate to the gas streams in reverse order.
Additional embodiments of the invention are directed to cluster tools comprising at least one atomic layer deposition system described. The cluster tool has a central portion with one or more branches extending therefrom. The branches being deposition, or processing, apparatuses. Cluster tools which incorporate the short stroke motion require substantially less space than tools with conventional deposition chambers. The central portion of the cluster tool may include at least one robot arm capable of moving substrates from a load lock chamber into the processing chamber and back to the load lock chamber after processing. Referring to
Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made to the method and apparatus of the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention include modifications and variations that are within the scope of the appended claims and their equivalents.
This application is a continuation of U.S. patent application Ser. No. 13/037,992, filed Mar. 1, 2011, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13037992 | Mar 2011 | US |
| Child | 13189692 | US |
