Systems and processes that singulate materials

Systems and methods for material singulation. According to some embodiments, methods for material singulation may include applying a first laser output to the material, the first laser output causing a modification of a material property of the material when exposed to the first laser output; and applying a second laser output to the material that was exposed to the first laser output to cause singulation of the material in such a way that surfaces created by the singulation of the material are substantially free from defects.

FIELD OF THE TECHNOLOGY

The present technology relates generally to laser processing of materials, and more specifically, but not by way of limitation, to systems and methods that singulate materials.

BACKGROUND

Generally speaking, singulation is a material separation process that often involves the application of chemical processes and/or mechanical forces to materials, particularly brittle materials, such as strengthened glass. Other common examples of materials that are often processed to create products via singulation include, but are not limited to, amorphous solid materials, crystalline materials, semiconducting materials, a crystalline ceramics, polymers, resins, and so forth.

SUMMARY OF THE TECHNOLOGY

According to some embodiments, the present technology may be directed to methods for material singulation. The methods may include: (a) applying a first laser output to the material, the first laser output causing a modification of a material property of the material when exposed to the first laser output; and (b) applying a second laser output to the material that was exposed to the first laser output to cause singulation of the material while substantially reducing the impartation of defects into the material.

In other embodiments, the present technology may be directed to laser devices for causing material singulation. These laser devices may include: (a) a first laser device that generates laser output for modifying one or more material properties of a material when applied to at least a portion of the material; and (b) a second laser device that generates laser output that, when applied to the material exposed to the laser output of the first laser device, produces a singulated product while substantially reducing the impartation of defects into the product.

In additional embodiments, the present technology may be directed to singulated products created by a process. In some embodiments, the process may include: (a) providing a stock of material; (b) applying a first laser output to the stock material along a beam path, the first laser output causing a modification of a material property of the stock material along the beam path; and (c) applying a second laser output along the beam path to cause separation of the singulated material from the stock material, along the beam path in such a way that surfaces of the singulated material, created by the separation, are substantially free from defects.

DETAILED DESCRIPTION

It will be understood that like or analogous elements and/or components, referred to herein, may be identified throughout the drawings with like reference characters. It will be further understood that several of the figures are merely schematic representations of the present technology. As such, some of the components may have been distorted from their actual scale for pictorial clarity.

The present technology relates generally to laser processing of materials, and more specifically, but not by way of limitation, to systems and methods that singulate materials, particularly brittle materials, by applying two or more types of laser output to the material, wherein the resultant singulated product is substantially free from defects.

Singulation allows for the separation of the material into individual products, or the milling of features into the material. Common singulation processes often involve numerous processing steps that are conducted slowly and iteratively in an attempt to avoid introducing defects such as micro-cracks or chips into the final product. Even with multi-step processes, current processes have low yield rates as any application of mechanical forces to the material can easily impart defects into the material.

Therefore, what is needed is a simplified process for singulating materials that does not require the use of mechanical material separation devices and/or processes.

Generally speaking, the present technology may include synchronous exposure of a material to two or more different types of laser beam output where each type of laser beam output induces a different physical mechanism of change to the material. The combination of these exposures creates a product with a clean, defect-free shape. A product with a clean, defect-free shape may also be referred to as a product having surfaces that are “substantially smooth.”

As stated above, common examples of materials that are often processed to create products via singulation include, but are not limited to, amorphous solid materials, crystalline materials, semiconducting materials, a crystalline ceramics, polymers, resins, and so forth.

For example, a sheet of strengthened glass may be subjected to two or more types of laser beam output to transform the sheet of strengthened glass into one or more touchscreen substrates that can be utilized to create touchscreen devices. Examples of strengthened glass may include glass that has been improved by high temperature exposure or by chemical treatment, such as Gorilla Glass from Corning or Dragontrail from Asahi. The sheet of strengthened glass may be especially thin—approximately 0.5 mm or thinner—which may impose increased susceptibility to defect impartation during conventional singulation methods.

Broadly speaking, the first laser output may induce a modification into the material and the second laser output may cause separation of the material at the modification. This two step process may create a singulated product having edge surfaces (as well as an overall product) that are substantially free from defects such as cracks or other surface irregularities/variations. That is, the present technology creates singulated products that have smoother singulated edges, more uniform planar surfaces, lower surface roughness, and greater mechanical strength relative to singulated products created via mechanical processes.

The present technology may be utilized to create singulated products with greatly varying geometrical configurations. Additionally, the systems and methods provided herein may be utilized to fabricate features into products with fine precision. Examples of features may include, but are not limited to slits, apertures, grooves, notches, etching, and so forth.

More specifically, a first laser beam may induce a discrete change to the molecular structure of the material along a beam path (also known as a tool path). The modification may comprise any of: a separation of molecular bonds in the material lattice, a geometrical reorientation of molecular constituents, and/or spatial movement of molecular species—just to name a few. Modifications may manifest macroscopically as a perturbation to a refractive index, an optical absorption, a variation in mechanical stress relative to the rest of the material, or a change in the physical density of the material.

In some embodiments, the second laser beam may follow the same path as the first laser beam and create a heating effect along the path that produces complete separation between sections of the substrate (along the modification) along the path traced by the laser beams. The two laser beams may be imaged onto the substrate with very little time delay. That is, there may be very little time delay between the delivery of the second beam after the delivery of the first beam (in some cases within a fraction of a second). Moreover, the two laser beams may be imaged using a single motion control and beam delivery apparatus. The exposure of the substrate to the two laser beams may occur substantially simultaneously so as to function as one laser beam with respect to time, yet the net material modification (e.g., singulation) is produced by the combined effects of two discrete laser induced mechanisms.

According to other exemplary embodiments, the present technology may utilize a short pulse laser to produce a first modification in the material and a long pulse or continuous wave laser to separate the material. The peak power associated with the short pulse laser may readily invoke any of the aformentioned molecular perturbations, while material exposed to the short pulse laser remains in a solid phase. It will be understood that these perturbation may be caused by rapid acceleration of electrons in response to application of the strong electric field of the short laser pulse to the material. The first modification may include any of a family of ionization effects, such as discontinuities in the lattice pattern (molecular level) of the material.

The second laser may generate a laser beam with a relatively high average power and low peak power. The laser beam may generate heat in the material through optical absorption. Localized heating within the second laser beam exposure area may selectively heat the modification created by the first laser beam and cause the material to separate along the lattice pattern discontinuity (e.g., the modification). Other causes for separation may include propagation of an acoustic shockwave (generated by the application of the laser beam of the second laser) through the area of material modification, and/or to severe thermal gradation of the area of material modification.

FIG. 1illustrates an exemplary singulation system (hereinafter “system100”) for use in practicing embodiments of the present technology. Generally speaking, the system100may comprise a first laser device105and a second laser device110that are each selectively coupled with a beam delivery assembly115. Each of the first and second laser devices will be discussed in greater detail infra. For the purposes of clarity, the first and second laser devices105and110are shown as being disposed within the same housing120, although it will be understood that the first and second laser devices may be housed separately from one another, and optionally in separate systems (not shown).

The beam delivery assembly115may be generally described as comprising optical and/or structural components that are utilized to focus and direct laser beams generated by the first and second laser devices105and110. The construction and operation of beam delivery assemblies would be well known to one of ordinary skill in the art with the present disclosure before them. Therefore, a detailed discussion of the beam delivery assembly115will be omitted for the purpose of brevity.

The system100may also include a platform125positioned below the first and second laser devices105and110. The platform125may be utilized to support a material130, also known as a stock material.

Referring now toFIGS. 1-2Bcollectively, the first laser device105may include any one of a number of different types of lasers that is adapted to generate a laser beam135that induces a primarily electronic energy excitation within the material130. It will be understood that the first laser device105may generate a laser beam that comprise a wavelength of light selected from any of visible, near infrared, or ultraviolet.

Additionally, the first laser device105may utilize a laser pulse duration of less than or equal to about ten nanoseconds. In other embodiments, the first laser device105utilizes a laser pulse duration of less than or equal to about fifty picoseconds. In some embodiments, the first laser device105may utilize a laser pulse duration of less than or equal to about one picosecond. The laser pulse duration of the first laser device105may be selected based a desired electric field strength that is to be generated within the irradiated area (desired area of modification). The laser pulse duration and laser pulse strength may be varied based upon the physical properties of the material such as density and opacity.

The first laser device105may selectively apply a laser beam to the material along a beam path140, or according to a pattern. Selective adjustments of the beam delivery assembly115may cause electronic energy excitation to any depth of the material (seeFIG. 3). Additionally, the amount of electronic energy excitation may be selectively adjusted by varying additional parameters of the first laser device105such as beam delivery speed and beam energy level.

The electronic energy excitation of the material may cause a perturbation of molecules within the material along the beam path140. It will be understood that in general terms, perturbation of the material may include inducing a change in one or more physical properties of the material130. A perturbation may include, for example, a separation of the molecular bonds in molecular lattice of the material (also known as creating a lattice pattern discontinuity), a localized volume of removed material (also known as a scribe), a geometrical reorientation of molecules of the material, and/or a change in material density along the beam path—just to name a few.

FIGS. 2A and 2Billustrate a modification145that extends between a top surface150and a bottom surface155of the material130, along the length of the beam path140.

FIG. 3illustrates material modifications of varying length and depth within a material300. For example, a modification305may extend between a top surface310and a bottom surface315of the material300(similar to the modification145ofFIGS. 2A and 2B). Modification320is shown as extending from the top surface310to a depth within the material300. Modification325is shown as beginning at a distance below the top surface310and terminating at a predetermined distance above the bottom surface315. Modification330is shown as extending upwardly from the bottom surface315of the material300and terminating within the material300at a predetermined distance from the top surface310. These modifications are merely exemplary and illustrate that modifications may extend at any depth between the top surface310and the bottom surface315of the material300.

Additionally, the width of the beam path140may be selectively adjusted by varying the optical configurations of the beam delivery assembly115. According to some embodiments, the beam delivery assembly115may focus the output of the first laser device105to approximately 1 micrometer to 100 micrometers in width. One of ordinary skill in the art with the present disclosure before them will appreciate that the beam width may be selectively varied to vary the dimensions of the modification305.

Modifications to material properties of the material may be evidenced by inspection of the mechanical properties of the material. For example, a modification may induce a change in the refractive index (particularly for transparent or semi-transparent materials) of the material along the modification. Therefore, upon refractive inspection of the material, the modification may appear visually distinct from the unmodified material.

FIGS. 4A and 4Billustrate microscopic photographs of refractive inspection of a modified material400. The material400has been exposed to a first laser output that induced a modification405within the material400. It will be understood that the modification resulted in a change in the density of the material400along a beam path emitted by the first laser device. Inspection included application of light to the material. Upon application of light to the material, the modification405appears as a dark line that extends through the material400. This darkening is due to the light traveling more slowly or with greater absorption through the modification405relative to the rest of the material400adjacent (on either side) the modification405.

It is noteworthy to mention thatFIG. 4Billustrates the same portion of the material400asFIG. 4A, with the exception thatFIG. 4Bis focused three millimeters into the material400. Moreover, magnification and imaging of the material400is made possible because the material400is at least partially transparent and able to pass light therethrough.

FIG. 5illustrates separation (e.g., singulation) of modified material500(shown in an already singulated configuration) into separate sections, such as a first section505and a second section510. The first and second sections505and510are shown offset from one another for illustrative purposes only, to show an edge surface515of the first section505. A modified material will be understood to include a material that has previously been subjected to a first laser output of a first laser device105.

The singulation of the modified material500may be caused by laser output of the second laser device110along the beam path520. It is noteworthy to mention that the beam path520is shown as extending past the edges of the modified material500for illustrative purposes only.

The laser output of the second laser device110may cause a heating of the modified material500along the beam path520, which results in a separation or singulation of the modified material along the modification (represented by beam path520). It will be understood that the separation of the modified material500by the second laser device110produces a singulated product that is substantially free from defects. For example, an edge surface such as singulated edge surface515and corners525and530that are created during singulation are substantially free from defects such as cracking, chipping or misshaping. These defects may degrade mechanical integrity, fracture strength, and/or cosmetic value of the product. Although not shown, the second section510also includes a singulated edge surface that is substantially free from defects.

Although not shown, the laser beam generated by the second laser device110may be of sufficient width to increase the temperature of the material directly adjacent to the modified material. The increase in temperature to adjacent material aids in preventing the development of defects along the beam path520during singulation.

Depending upon the type of laser utilized, the second output of the second laser device110may generate an acoustic shockwave that propagates through the modified material500. This acoustic shockwave may cause failure of the modified material along the beam path520. It will be understood that a shockwave may be generated by the output of an ultrafast laser device.

In other embodiments, the laser beam of the second laser device110may utilize laser pulse durations that are greater than or equal to about ten picoseconds. Other embodiments may include laser pulse durations of greater than or equal to about one microsecond.

In some embodiments, the second laser output may comprise a wavelength selected from a range of approximately 0.78 to three micrometers (i.e. the near infrared light spectrum), inclusive. In other embodiments, the second laser output may comprise a wavelength selected from a range of approximately three to fifty micrometers (i.e. the mid infrared light spectrum), inclusive. In other applications, the second laser output comprises a wavelength selected from a range of approximately fifty to one thousand micrometers (i.e. the far infrared light spectrum), inclusive. In yet other embodiments, the second laser device110includes a continuous wave laser device.

As mentioned above, the width of the beam of the second laser device110may be selectively adjusted based upon the width of the modification145. The width of the beam may be selectively adjusted by varying the optical configuration of the beam delivery assembly115. According to some embodiments, the beam delivery assembly115may focus the output of the second laser device110to approximately 10 micrometers to 10 mm in width (based upon the width of the modification caused by the output of the first laser device, or approximately 1 to 100 micrometers).

In some embodiments, the system100may apply laser output from the first laser device105along the entire length of the beam path140of the material130before applying laser output from the second laser device110along the entire length of the beam path140. In other embodiments, laser outputs of both the first and second laser devices105and110occur substantially simultaneously. That is, the application of the output of the second laser device110may occur after the application of the output of the first laser device105. For example, a laser beam of the second laser device110may follow behind (at a predetermined distance) the laser beam of the first laser device105, along the beam path140.

While the above described examples contemplate separating a simple rectangular material into two separate rectangular sections, one of ordinary skill in the art will appreciate that the system100may be utilized to produce finely-shaped products from a stock material. For example, a sheet of strengthened glass may be processed to produce a plurality of touchscreen substrates according to the methods described above. The touchscreen substrates may have any desired geometrical configuration.

Additionally, fine details may be fabricated into the touchscreen substrates such as apertures or ports, utilizing the aforementioned processes.

In other exemplary uses, semiconductor substrates may be processed by the present technology. For example, features such as through-silicon vias may be fabricated into the semiconductor substrate with the use of the present technology.

According to some embodiments, rather than having separate first and second laser devices, the system may include a single laser generating and emitting device that can create a variety of laser output. For example, the single laser generating and emitting device can produce both short and long pulse duration laser beams. Moreover, the single laser generating and emitting device may also output laser beams that fall within any suitable wavelength.

With regard to both the first and second laser devices105and110, it will be understood that these laser devices may utilize any one of a number of techniques for laser beam delivery (e.g., propagation toward, or within) a material. Non-limiting examples of laser beam delivery techniques include linear and/or non-linear optical propagation, static and/or transient waveguiding effects, optical diffraction, refraction, reflection, filamentation, self-focusing, along with any other techniques/devices for placement of laser energy relative to any of a volume, a plane, a line, or a point that would be known to one of ordinary skill in the art with the present disclosure before them.

Additionally, the combined effects of the laser devices disclosed herein may be configured for use in a wide variety of micro-fabrication applications that include, but are not limited to, shaping precious gemstones, semiconductor wafer scribing or singulation, surgical cutting of hard tissue, and marking of indicia such as serial numbers or part numbers inside transparent devices—just to name a few.

Referring back toFIG. 1, in operation, a stock of material130is placed upon the platform125of the system100. In some embodiments, executable instructions may be utilized to selectively vary the operational characteristics of the system100to singulate products from a stock material. These instructions may be executed by the processor of a computing system (not shown) such as computing system600described with reference toFIG. 6. The computing system may be particularly purposed to control the operation of the system100to singulate materials.

The executable instructions may include laser parameters for the first laser device105that are selected based upon the physical properties of the material130. The physical properties of the material130may be input by a user or input via data gather from one or more sensors (not shown). Next, the beam delivery assembly115is selectively adjusted to focus the beam of the first laser device105to a particular depth and width relative to the material130. The output of the first laser device105is applied along a beam path140according to a desired product profile. That is, the beam path140approximates an outline of the desired product profile (e.g., rectangular, circular, polygonal, irregular, and so forth).

Application of the output of the first laser device105causes a modification145of the material properties of the material130along the beam path140. To cause separation or singulation of the material130along the beam path140, the laser parameters for the second laser110are selectively adjusted, again, based upon the physical properties of the material and the modification145induced within the material130.

Next, the configuration of the beam delivery apparatus115is selectively adjusted. For example, the width of the beam of the second laser device110is selected such that the beam of the second laser device110is directed at portions of the material adjacent to the modification145, as well as the modification145itself.

Application of the output of the second laser device110causes singulation or separation of the product (not shown) from the stock material130along at the modification145without imparting defects into the edge surfaces of the material130(or any other portion of the material130).

FIG. 6illustrates an exemplary computing system600that may be used to implement an embodiment of the present technology. The system600ofFIG. 6may be implemented in the contexts of the likes of computing systems, networks, servers, or combinations thereof. The computing system600ofFIG. 6includes one or more processors610and main memory620. Main memory620stores, in part, instructions and data for execution by processor610. Main memory620may store the executable code when in operation. The system600ofFIG. 6further includes a mass storage device630, portable storage medium drive(s)640, output devices650, user input devices660, a graphics display670, and peripheral devices680.

The components shown inFIG. 6are depicted as being connected via a single bus690. The components may be connected through one or more data transport means. Processor unit610and main memory620may be connected via a local microprocessor bus, and the mass storage device630, peripheral device(s)680, portable storage device640, and display system670may be connected via one or more input/output (I/O) buses.

Mass storage device630, which may be implemented with a magnetic disk drive or an optical disk drive, is a non-volatile storage device for storing data and instructions for use by processor unit610. Mass storage device630may store the system software for implementing embodiments of the present technology for purposes of loading that software into main memory620.

Portable storage device640operates in conjunction with a portable non-volatile storage medium, such as a floppy disk, compact disk, digital video disc, or USB storage device, to input and output data and code to and from the computer system600ofFIG. 6. The system software for implementing embodiments of the present technology may be stored on such a portable medium and input to the computer system600via the portable storage device640.

Input devices660provide a portion of a user interface. Input devices660may include an alphanumeric keypad, such as a keyboard, for inputting alpha-numeric and other information, or a pointing device, such as a mouse, a trackball, stylus, or cursor direction keys. Additionally, the system600as shown inFIG. 6includes output devices650. Suitable output devices include speakers, printers, network interfaces, and monitors.

Display system670may include a liquid crystal display (LCD) or other suitable display device. Display system670receives textual and graphical information, and processes the information for output to the display device.

Peripherals680may include any type of computer support device to add additional functionality to the computer system. Peripheral device(s)680may include a modem or a router.

It is noteworthy that any hardware platform suitable for performing the processing described herein is suitable for use with the technology. Computer-readable storage media refer to any medium or media that participate in providing instructions to a central processing unit (CPU), a processor, a microcontroller, or the like. Such media may take forms including, but not limited to, non-volatile and volatile media such as optical or magnetic disks and dynamic memory, respectively. Common forms of computer-readable storage media include a floppy disk, a flexible disk, a hard disk, magnetic tape, any other magnetic storage medium, a CD-ROM disk, digital video disk (DVD), any other optical storage medium, RAM, PROM, EPROM, a FLASHEPROM, any other memory chip or cartridge.