Laser dicing system for filamenting and singulating optical devices

A process of producing optical devices is provided including transferring a first substrate comprising one or more devices to a laser dicing tool, the laser dicing tool including a filamentation stage and a singulation stage. One or more device contours are created on the first substrate in the filamentation stage. The optical devices are singulated from the first substrate along the one or more device contours in the singulation stage. The devices are transferred to storage or for further backend processing.

BACKGROUND

Field

Embodiments of the present disclosure generally relate to a laser dicing system for optical devices.

Description of the Related Art

In the manufacture of optical devices, such as optical devices for virtual reality or augmented reality, one or more devices having structures with sub-micron critical dimensions are disposed on a substrate for processing, such as a front side of the substrate. To manufacture the optical devices, a surface of the substrate having the one or more devices disposed on the surface must be retained on a substrate support assembly without contacting the one or more devices, and a plurality of substrates must be processed at a plurality of processing stations throughout the manufacturing process. Current systems for processing substrates are throughput limited due to the number of processing stations for processing the substrates and because of the care that is used for handling the substrates. Once manufactured, the optical devices are separated from the substrates without deforming the optical devices, which can be challenging.

Accordingly, what is needed in the art are methods for processing substrates without deforming the optical devices, and a processing system to handle the substrates at high throughput and without deforming the substrate.

SUMMARY

In one embodiment, a process of producing optical devices is provided. The process includes transferring a first substrate comprising one or more devices to a laser dicing tool, the laser dicing tool comprising a filamentation stage and a singulation stage. One or more device contours are scribed on the first substrate in the filamentation stage. The first substrate is cut along one or more device contours in the singulation stage and the devices are transferred for further processing.

In another embodiment, a system for fabricating devices is provided. The system includes a plurality of stages, each stage disposed below a corresponding optical head of a plurality of movable optical heads with each optical head corresponding to a laser. A conveyor system is coupled to the plurality of stages, and a sorting system includes a robot capable of moving devices from the conveyor system.

In yet another embodiment, a system for fabricating devices is provided including a first stage disposed below a first optical head. The first optical head is operable to direct a first laser beam from a first laser source toward the first stage. A second stage is disposed below a second optical head. The second optical head is operable to direct a second laser beam from a second laser source toward the second stage. The first stage and second stage are operable simultaneously with respect to one another. A forward conveyor system is coupled to the plurality of stages. A vision assembly includes a camera disposed above the conveyor system, and a sorting system includes a robot capable of moving devices from the conveyor system. The robot is communicatively coupled to the vision assembly.

DETAILED DESCRIPTION

Embodiments of the present disclosure generally relate to a laser dicing system for optical devices, and methods for processing optical devices. The system includes several processing stations capable of operating simultaneously with respect to one another. A two part laser dicing system is included which subjects the substrate to a first laser and to a second laser. The system provided herein enables simultaneous processing of a first substrate with the second laser as a second substrate is processed with the second laser. The system is fully automated and substrates are easily transferred from station to station using a substrate carrier. In this manner, throughput and automation is enhanced.

FIG.1is a perspective, frontal view of a first surface102(i.e., top surface) of a substrate100. The substrate100includes a second surface104(i.e., bottom surface visible inFIG.2) opposite the first surface102(as shown inFIG.2). The substrate100may be glass, plastic, silicon carbide, polycarbonate, or any other suitable material. In one embodiment, which can be combined with other embodiments described herein, the substrate100is transparent, such as transparent glass. The materials may have rollable and flexible properties. In one embodiment, which can be combined with other embodiments described herein, the substrate100has a thickness116(shown inFIG.2) of less than about 1 millimeter (mm). In some embodiments, the thickness is less than 0.5 mm. The substrate100includes one or more optical devices106, disposed on the first surface102and/or the second surface104of the substrate. The one or more optical devices106can include structures114(i.e., fins) having sub-micron critical dimensions, e.g., nano-sized critical dimensions.

The embodiments of the substrate support assembly200(shown inFIG.2) described herein are operable to retain the substrate100having one or more optical devices106without contacting the structures114and without deforming the substrate100.FIG.2is a schematic, cross-sectional view of a system201including a substrate support assembly200. The substrate support assembly200is capable of supporting substrates100with different thicknesses, shapes and sizes for laser processing.

The system201includes one or more optical heads205, such as a first swappable optical head. The first optical head205is configured to receive energy from one or more lasers from one or more laser sources, such as a first laser from a first laser source213. The one or more laser sources direct one or more laser beams, such as first laser beam209to the second surface104of the substrate100. The first surface having the optical devices106is faced away from the first laser beam209. It has been found that facing the optical devices106away from the first laser beam209protects the structures114on the optical devices106to prevent device defects. The first laser beam209is operable to heat the edges of the optical devices106on the substrate100and provide an outline of the optical devices. In some embodiments, that can be combined with other embodiments described herein, the one or more laser sources includes an infrared laser and a CO2laser source. The laser sources can be any suitable electromagnetic energy of various wavelengths, such as ultraviolet, infrared, and the like.

The substrate100is retained on a support surface204of the substrate support assembly200. In one embodiment, which can be combined with other embodiments described herein, a body202of the substrate support assembly200is coupled to an actuator211. The body202of the substrate support assembly200can be made from any suitable material, such as aluminum. The actuator211, in operation, moves the body202along an x-direction, a y-direction and/or a z-direction. In some embodiments, which can be combined with other embodiments described herein, one or more actuators211can be coupled to one or more stages to move the substrate100disposed thereon. The substrate support assembly200includes a controller206operable to be in communication with a system controller (not shown) and is operable to control aspects of the substrate support assembly200during processing.

The body202of the substrate support assembly200includes a plurality of projections208. In one embodiment, which can be combined with other embodiments described herein, the body202and the projections208include stainless steel and/or aluminum containing materials. In another embodiment, which can be combined with other embodiments described herein, the body202and the projections208include ceramic containing materials.

The first surface102(i.e., top surface) of the substrate100is securable to the support surface204of the plurality of projections208without the one or more optical devices106contacting the support surface204. Adjacent projections of the plurality of projections208form pockets214. The pockets214have a width216and a length corresponding to a width120and a length122(as shown inFIG.1) of the one or more optical devices106and a height222. The plurality of projections208correspond to portions124of one of the first surface102and the second surface104without one of the optical devices106disposed thereon. The pockets214can also include one or more posts240that support the optical devices106at portions126of the optical device without structures114disposed thereon. When the substrate100is secured to the support surface204of the substrate support assembly200, regions220are formed, in each of the pockets214, between the body202of the substrate support assembly200and the optical devices106of one of the first surface102and second surface104secured to the support surface204.

Each of the pockets214are operable to be coupled to a pocket conduit224in fluid communication with a vacuum source228via a vacuum flow controller226, such as a MFC. The vacuum source228is operable to supply vacuum pressure through a respective pocket conduit224to a respective pocket214to retain portions of the substrate100corresponding to the support surface204of the projections208by maintaining a vacuum pressure in a respective region220. In one embodiment, which can be combined with other embodiments described herein, the vacuum pressure is about 380 Torr to about 760 Torr. The controller206is operable to operate each vacuum flow controller226according to embodiments described herein.

FIGS.3A and3Bare schematic, top views of substrate carriers302A,302B according to some embodiments. In some embodiments, which can be combined with other embodiments described herein, the substrate100is retained on a substrate carrier, such as substrate carrier302A,302B. In some embodiments, which can be combined with other embodiments described herein, the substrate support assembly200is capable of receiving a substrate retained on a substrate carrier302A,302B, such as substrate carrier302A,302B. The substrate carrier302A,302B includes a base plate304. The base plate304is made from a lightweight material such as a material including carbon fiber. It has been found that the lightweight material of the base plate304enables the carrier to be transferred easily between processing stations, such as transferring the carrier302A,302B with a pick and place robot. In some embodiments, which can be combined with other embodiments described herein, the base plate is about 2 kg or less, such as about 1.5 kg or less, such as about 1 kg to about 1.4 kg. Conventional base plates are greater than about 2 kg, such as greater than about 3 kg. The base plate304is capable of retaining substrates of different shapes and sizes. The substrate carrier302A,302B includes a vacuum diaphragm306A,306B which approximates a shape and size of a substrate to be retained. The vacuum diaphragm306A shown inFIG.3Aaccommodates a round substrate with a first diameter, and vacuum diaphragm306B shown inFIG.3Baccommodates a round substrate with a second diameter. The first diameter shown inFIG.3Ais smaller than the second diameter shown inFIG.3B. The substrate is retained on the substrate carrier302A,302B using a retaining ring308A,308B, such as a clamp ring. The retaining ring308A,308B is positioned above the substrate100and is capable of securing the substrate100using magnets disposed below the substrate100. The substrate100is assembled on the substrate carrier302A,302B to provide a stack in a build station, as shown in the build station402depicted inFIG.4. In some embodiments, which can be combined with other embodiments described herein, the substrate carrier is capable of a substrate with a diameter of about 100 mm to about 350 mm, such as about 150 mm, about 200 mm, or about 300 mm.

FIG.4is a flow diagram400of a system for processing substrates andFIG.5is a plan view of a system500for processing substrates according to an embodiment. The flow diagram of the system is described herein with reference to the system shown inFIG.5. The system500includes a plurality of load ports502A,502B,502C,502D, such as a front opening unified pod (“FOUP”). The substrates100and substrate carriers302A,302B are stored in separate ports until the substrates100are ready for processing. Each load port includes a plurality of substrates100or a plurality of substrate carriers302A,302B. In some embodiments, which can be combined with other embodiments described herein, ports502A and502D include substrates100and ports502B and502C include substrate carriers302A,302B.

The substrates100and substrate carriers302A,302B are transferred to a build station402for assembly. For example, substrates from port502A and substrate carriers from port502B are transferred to build station402A. Similarly, substrates from port502D and carriers from port502C are transferred to build station402B. In operation410, the substrates100are assembled onto substrate carriers302A,302B in the build station402. Each substrate100together with a substrate carrier302A,302B forms a stack. The stack is transferred from the build station402to a laser dicing assembly404. In operation412, the stack is aligned in preparation for dicing. The alignment includes positioning the stack on a stage for laser dicing. Fiducials placed about the substrate are used as a reference for determining alignment. As used herein, the term “fiducials” refer to markings disposed on a substrate which are readable to determine an alignment of the substrate. Each stack is retrieved from the build station by a robot and aligned to a substrate support assembly200as depicted inFIG.2. The substrate100or stack is secured on the body202of the substrate support assembly200of a laser dicing tool by the robot. The robot508can move substrates100to the laser dicing tool while the laser dicing assembly404is in operation. The simultaneous operation enables high substrate throughput and efficiency.

In operation414, the substrate100is patterned with a laser dicing process which outlines the optical devices in the substrate. In operation416, the substrate100is heated through the outlines to singulate the optical devices while supported by the substrate carrier302A,302B. Heating the outlines separates the devices from the substrate using thermal expansion. The power densities of the power beams used are directly proportional to the laser spot size. The processed substrate is transferred to a backend packaging station406. The processed substrate is transferred using one or more forward conveyors507. The backend packaging station406includes a vision station506for inspecting the optical devices and a sorting station. The sorting station includes a pick and place robot508for sorting the optical devices (e.g., operation418). The vision station506includes one or more cameras disposed above the processed substrate100. An image of the substrate is captured by the one or more cameras to determine alignment and to identify the presence of defective optical devices. In some embodiments, which can be combined with other embodiments described herein, the substrate is illuminated by a side LED light to illuminate the edges of the optical devices for imaging. In this manner, the vision station506camera is capable of determining the location and orientation of each of the optical devices. The vision station506is communicatively coupled to the robot508such that robot508is capable of transferring the substrate carrier302A,302B without contacting the optical devices and transferring optical devices from the substrate. The backend packaging station406includes one or more forward conveyors507, such as conveyor belts. The stacks are transferred by the forward conveyors507to one or more robots508. The robots508are configured to remove the optical devices106from the stacks.

The defective optical devices are discarded (e.g., operation430) and the optical devices without defects are transferred to backend packaging (e.g., operation422). The packaged optical devices are further processed at backend processors, such as in an edge blackening station (e.g., operation428). The substrates100with optical devices removed, are separated from the substrate carriers302A,302B (e.g., operation420) and the broken substrates100are separated from the carriers (e.g., operation432). The laser dicing process performed on the stack described herein enables the substrate carrier within the stack to collect debris that results from dicing. The carriers are removed from the substrate with the debris. The resulting optical devices with structures facing away from the lasers are free of defects and contaminants such as particulates from the debris left behind by laser dicing. A plurality of backend storage ports or trays514A,514B,514C,514D are used to store the separated and sorted components, such as defective optical devices, non-defective optical devices, and different types of optical devices.

The carriers are cleaned (e.g., operation424) at cleaning station510using a vacuum module and the cleaned carriers are reused for further processing (e.g., operation426). The carriers with the debris can be cleaned in situ and collected for future use. In some embodiments, which can be combined with other embodiments described herein, the cleaned carriers are positioned on a return conveyor512and returned to a load port or a build station in a continuous loop process. In some embodiments, which can be combined with other embodiments described herein, the return conveyor comprises a cross conveyor portion and a return portion. The return portion of the conveyor is substantially parallel to the front conveyor. One or more of the operations410to432are carried out simultaneously with one another in a continuous process of multiple substrates. In some embodiments which can be combined with other embodiments described herein, a substrate is processed in one operation while another substrate is processed in another operation.

FIG.6is a schematic, top view of a laser dicing assembly404according to an embodiment. The laser dicing assembly404includes two or more stages620,630. The stages620,630are each capable of moving in each direction (X, Y, Z axis) and rotating about the Z axis (e.g.,8). Each stage includes a substrate support as described with reference toFIG.2. Each stage (e.g., first stage620, second stage630) corresponds to a laser source (e.g., first laser source602, second laser source632). The first laser source602emits a first laser along a first beam path604. The first beam path is directed to the first optical head612using a first set of one or more turning mirrors or steerers606,608, and a first set of one or more beam expanders610. The first optical head612is movable along a line parallel to the X-axis and directs the first laser beam toward a first substrate disposed on first stage for processing the first substrate. The first laser beam is from an infrared laser source, or any laser capable of filamenting, or dicing in a substrate. The filamentation process includes exposing the stack to a first laser beam to heat and outline (e.g., “scribe contour”) the edges of an optical device on the stack. The first optical head612is positioned above the second stage630for processing a second substrate disposed on the second stage.

Similarly, the second laser source632emits a second laser along a second beam path634. AlthoughFIG.6depicts the first and second optical heads612,642to be disposed on different positions along the Y-axis and the same position along the Z-axis, it is also contemplated for the first and second optical heads612,642to be on the same position along the Y-axis and on different positions along the Z-axis. Alternatively, the optical heads612,642are positioned at different locations along the Z-axis and the Y axis. It is appreciated that positioning the optical heads612,642along different positions along the z-axis enables processing of substrates simultaneously using a relatively small space. The second laser beam is from a CO2laser source, or any laser capable of singulating the optical devices from the substrate. The singulation process releases the optical device at the scribe contour created by filamentation. The first and second laser beams are selected based on the composition of the substrate, such as a glass substrate or a silicon carbide substrate. In some embodiments, which can be combined with other embodiments described herein, the substrate is a silicon carbide substrate and the first laser beam source includes a nanosecond (ns) UV laser. Each of the first and second laser beams are selected from a group consisting of UV, green, and IR. In particular, UV, green, and IR lasers can be used for filamentation and/or singulation of silicon carbide or glass substrates. Additionally, CO2lasers can be used for singulation of glass substrates. The laser sources include picosecond, femtosecond, or nanosecond laser sources. The second beam path634is directed to the second optical head642using a second set of one or more turning mirrors and steerers636,638, and a second set of one or more beam expanders640. The second optical head642is movable along a line parallel to the X-axis and directs the second laser beam toward the first substrate disposed on the first stage620. The second optical head642is positioned above the second substrate disposed on the second stage630. The system enables processing different substrates simultaneously with respect to one another using dedicated optical heads disposed above the stages. Each optical head includes a focusing element, a plurality of optical lenses. Although IR and CO2lasers are described and depicted herein, the filamentation and singulation processes can be done using any suitable laser or cutting techniques available. It has been found that filamentation and singulation reduces chipping, microcracks, delamination and other damage that can occur in optical device fabrication. The system described herein is capable of operating both filamentation and singulation simultaneously with one another and with other tools and operations used to process substrates allowing for high throughput.

In one embodiment, which can be combined with other embodiments of the present disclosure, a first stack can be processed in the filamentation process on a first stage620followed by the singulation process. As the first stack is processed in the singulation process, a second stack can be processed at the filamentation process. The first laser source602can transmit infrared (“IR”) energy to a first optical head612, the first optical head612can direct the energy to the stacks disposed on the first stage620. In some embodiments, which can be combined with other embodiments described herein, the first optical head is movable within a first plane and the second optical head is movable within a second plane. The first plane and the second plane are the same or are different with respect to the Z-axis.

In summation, the present disclosure generally relates to a laser dicing system for optical devices, substrate support assemblies for retaining a surface of a substrate having one or more optical devices disposed on the surface without contacting the one or more optical devices and deforming the substrate, and methods for processing optical devices.

While the foregoing is directed to examples of the present disclosure, other and further examples of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.