Patent Application
20130243971
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.
One or more embodiments of the invention are directed to deposition systems comprising a processing chamber, a gas distribution plate in the processing chamber and at least one laser source. The gas distribution plate has a plurality of elongate gas ports that direct flows of gases toward a surface of a substrate. The at least one laser source emits a laser beam directed along at least one of the elongate gas ports between the gas distribution plate and the substrate.
In some embodiments, the gas distribution plate comprises a plurality of first reactive gas injectors that direct flows of a first reactive gas toward a substrate and at least one second reactive gas injector that directs a flow of a second reactive gas different from the first reactive gas toward a substrate. In one or more embodiments, the at least one laser beam is directed along the length of one or more of each of the first reactive gas injectors and the at least one second reactive gas injectors.
In some embodiments, there is one laser source. In one or more embodiments, the one laser source emits a beam that is split with at least one beam splitter to direct the one laser beam along multiple elongate gas injector.
In some embodiments, there are at least two laser sources emitting laser beams and each laser beam is directed along a different elongate gas injector.
In some embodiments, the laser source is located outside of the processing chamber and the laser beam is directed through a window in a wall of the processing chamber. In one or more embodiments, the window is heated. Some embodiments further comprise a purge gas flow between the window and the gas distribution plate.
Additional embodiments of the invention are directed to deposition systems comprising a processing chamber, a gas distribution plate in the processing chamber and at least one laser source. The gas distribution plate directs flows of gases toward a surface of a substrate. The at least one laser source has a laser beam directed along a path adjacent to the gas distribution plate between the gas distribution plate and the substrate.
In some embodiments, there is one laser source and the system further comprises at least one beam splitter that directs the one laser beam along multiple paths.
In some embodiments, there are at least two lasers sources emitting at least two laser beams. One or more embodiments further comprise at least one beam splitter that directs at least one of the at least two lasers beams along multiple paths.
In some embodiments, the at least one laser source is positioned so that when a substrate is present in the system, the laser beam is up to about 50 mm from the substrate.
In some embodiments, the laser beam is one of a continuous laser and a pulsed laser.
Further embodiments of the invention are directed to methods of processing a substrate. The substrate is sequentially contacted with a flow of a first precursor and a flow of a second precursor from a gas distribution plate to form a layer on the substrate. At least one of the first precursor and the second precursor is activated with at least one laser beam directed adjacent the gas distribution plate.
In some embodiments, each of the first precursor and second precursor flow from separate elongate gas ports and the at least one laser beam is directed along a length of at least one of the elongate gas ports.
Some embodiments further comprise pulsing the laser beam to coincide with the flow of one or more of the first precursor and the second precursor.
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. Some embodiments of the invention are directed to atomic layer deposition apparatuses (also called cyclical deposition) incorporating a gas distribution plate, reciprocal linear motion and a horizontal laser.
Embodiments of the invention use one or more lasers to stimulate gaseous precursors in and ALD reactor where the precursors are introduced horizontally separated. This may have the advantage of increasing the efficiency of precursor decomposition, increase the rate of saturation and/or initiate/catalyze the reaction. Current ALD processes are challenged by process speed with delays due to time consumed in emptying and refilling of the two precursors which are sequentially introduced to the reactor. Embodiments of invention apply to the use of pyrolitic (thermal) and photolytic assist using lasers of different wavelength (IR, UV-excimer lasers) to effectively dissociate through direct dissociation or catalytic decomposition of precursors.
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 some 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 some 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 that transmit one or more gas streams to the substrate 60 and a plurality of vacuum ports disposed between each gas port that transmit the gas streams out of the processing chamber 20. In the 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. Where discrete rotational steps are used, it may be advantageous to rotate the substrate when it is in a position before and/or after the gas distribution plate.
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 some embodiments, 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 one or more embodiments, 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.
The embodiments of
The deposition system 100 includes at least one laser source (not shown) which emits a laser beam. As used in this specification and the appended claims, the term “laser source” means any device capable of emitting a collimated beam of light. Suitable laser sources include, but are not limited to, laser diodes. As used in this specification and the appended claims, the term “laser beam” means a beam of coherent light that that produced from a laser source. The terms “laser beam”, “laser”, “light beam”, “collimated light”, “coherent light”, and the like, are used interchangeably to describe a beam of light emitted by a laser source.
Some precursors require activation before they can be useful in ALD processes. Activation can be as simple as forming an excited species which can react with the substrate surface (or film on the surface) with a lower activation energy barrier. Some precursors require a catalyst for activation and the catalyst can be activated by the laser increasing the catalytic effect. In some embodiments, the laser has sufficient power and frequency to initiate a local plasma. The laser can be used to photolytically produce a useful precursor in the chamber by laser assisted activation of the reactant gases in a region parallel to and adjacent the substrate surface. In some embodiments, the laser light is used to photolytically produce a catalyst species that assists in the activation of reactant gases by directing the laser light parallel to and adjacent the substrate.
Suitable lasers can be continuous wave or pulsed lasers (e.g., nanosecond and femptosecond lasers). The wavelength of the laser can be varied to correspond to the activation energies required by the specific precursors. Ultraviolet, visible, infrared, near-infrared lasers, and others, can be used. For example an argon fluoride (ArF) laser, which emits light at about 193 nm (6.4 eV) may be used to activate ammonia by photolysis to produce NH and NH2 species. Other exemplary lasers include CO2 lasers. Additionally, more than one laser type can be employed simultaneously at the same gas injector, or at different gas injectors.
The laser source can be positioned to direct one or more beams of light along any or all of the elongate gas ports. The laser source can be located within the chamber or outside of the chamber. In some embodiments, the laser source is located outside of the chamber to avoid material depositing on the laser's lens. When the laser source is located outside of the chamber, there is a window in at least one wall of the chamber to allow the light beam to enter the processing area. The size and shape of the window can vary depending on the arrangement of laser(s) in the system and the desired path of the laser beam.
Depending on the mode of activation, the precursors being used and the desired film, amongst others, the position of the laser within the chamber. The laser beam can be directed along the length of any of the elongate gas injectors to activate gaseous species flowing from the injector. For example, if the first precursor requires activation, the laser beam can be directed along the front of the first precursor injector, or along the front of all of the first precursor injectors, if there are more than, and it is desired. The laser beam can be directed along any of the precursors injectors, purge gas injectors and vacuum ports as needed. In some embodiments, the laser(s) is directed along the length of one or more of each of the first reactive gas injectors and the at least one second reactive gas injectors.
The laser can be directed along the length of a purge gas injector to convert the otherwise inert gas into a state useful in the formation of a film. For example, a first precursor can be deposited on the substrate surface and then the otherwise inert gas flowing across the surface can activate the surface species before exposure to the second precursor.
The laser beam can be directed in front of the gas distribution plate a distance from the surface of the substrate. The distance from the substrate surface can be varied depending on the precursors. For example, the lifetime of the radicals (activated species) generated by the laser can be a factor in the useful distance from the substrate. When the activated species has a shorter lifetime, the laser beam will be more useful located closer to the substrate surface. In some embodiments, the laser beam is positioned so that when the substrate is present in the system, the laser beam is up to about 100 mm from the substrate surface, or up to about 50 mm from the substrate surface. In some embodiments, the laser beam is up to about 45 mm, 40 mm, 35 mm, 30 mm, 25 mm, 20 mm, 15 mm, 10 mm, 9 mm, 8 mm, 7 mm, 6 mm, 5 mm, 4 mm, 3 mm, 2 mm, 1 mm, or 0.5 mm from the substrate surface. In some embodiments, the laser beam has a width in the range of about 0.5 mm to about 1 m. In one or more embodiments, the laser beam has a width in the range of about 1 mm to about 0.5 m. The width of the beam can be static or dynamic throughout processing. A plurality of lasers can be employed to make the beam wider. The beam can be shaped or manipulated using any known technique including, but not limited to, cylindrical or diffracting optics.
The laser power can be controlled by a separate controller (not shown). The controller can be used to change the power of the laser, including turning the laser on and off, during processing of the substrate. For example, it may be useful to only use the laser for the deposition of the first few ALD layers, at which point the laser can be turned off. Additionally, the controller can power and coordinate multiple lasers, allowing for the rapid switching between lasers during processing. For example, hydrazine can be activated by a UV laser or a hydrogen radical can be generated by an IR laser. The controller is capable of rapidly switching between the UV laser and IR laser to generate both species.
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 one or more embodiments, the top surface 67 of the susceptor 66 includes a recess 68 configured to accept the substrate 60, as shown in
In embodiments with a window 177 there is potential for film deposition on the window 177, as with any other part of the processing chamber. However, deposition on the window 177 could result in, for example, decreased laser intensity reaching the target area (i.e., the gas distribution plate 30), no laser intensity reaching the target area and laser scattering. Therefore, the window 177 of some embodiments is heated to minimize deposition thereon. The window 177 can be heated by any suitable means including, but not limited to, heating lamps directed at the window, heating elements (e.g., ceramic heaters, resistive heaters) located around the edges of the window and ceramic heats directed at the window.
Another embodiment includes a purge gas flow between the window 177 and the gas distribution plate 30. The purge gas flow may help isolate the window 177 from reactive gases from the gas distribution plate 30. To include a purge gas flow, the processing chamber may include one or more of a purge gas source, a purge gas flow controller and a purge gas injector. The flow of the purge gas can be continuous or pulsed. In some embodiments, to maximize the benefit of a purge gas isolating the window, the purge gas flow is continuous. The purge gas flow can be directed anywhere throughout the processing chamber, not just in the area of the window. For example, there can be one or more purge gas flows (i.e., different purge gas injectors) spaced around the entire chamber body to help form a barrier between the gases from the gas distribution plate and the walls of the chamber.
In some embodiments, the processing chamber 20 includes a substrate carrier 65 that moves 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
In some embodiments, the reactive gas injectors on either end of the gas distribution plate 30 are the same so that the first and last reactive gas seen by a substrate passing the gas distribution plate 30 is the same. For example, if the first reactive gas is A, then the last reactive gas will also be A. If gas A and B are switched, then the first and last gas seen by the substrate will be gas B.
Referring to
Similarly,
Some embodiments of the invention are 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. As used in this specification and the appended claims, the term “consisting essentially of”, and the like, mean that the gas injector 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
The number and arrangement of the laser sources 171 can vary depending on the specific processing requirement.
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 require substantially less space than stand-alone tools. 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.
