JP2004526575A - Ultraviolet laser ablation patterning method of fine structure in semiconductor - Google Patents

Abstract

By using ultraviolet laser ablation, a pattern with a shape size smaller than 50 microns is formed at high speed directly in a semiconductor, especially silicon. These patterns are for the connection of integrated circuits and have very high aspect ratio through-holes, singulation of the processed semiconductor dies contained on the semiconductor wafer, and the work of microcircuits from the parent wafer. Microtab cutting for separating pieces. Diode-pumped Q-switching frequency tripled Nd: YAG, Nd: YVO ₄ or Nd: laser output pulse (32) from YLF, directed to the workpiece (12) at high speed precision using the composite beam positioner. The optics generates a Gaussian spot size or top hat beam profile of about 10 microns. The pulse energy used to rapidly ablate silicon using this focused spot size is greater than 200 μJ per pulse at a PRF greater than 5 kHz, preferably greater than 15 kHz. The laser pulse width measured at the full width at half maximum is preferably smaller than 80 ns.

Description

[Related application]
[0001]
This patent application claims priority from US Provisional Application No. 60 / 265,556 filed on January 31, 2001 and US Patent Application No. 09 / 803,382 filed on March 9, 2001. is there.
【Technical field】
[0002]
The present invention relates to a method and / or apparatus for high-speed formation of fine-dimension structural features by ablating semiconductors, particularly silicon, using the pulsed output of an ultraviolet (UV) laser.
BACKGROUND OF THE INVENTION
[0003]
In the semiconductor industry, various techniques are used to separate individual electronic devices, often referred to as semiconductor dies, from semiconductor wafers on which the electronic devices are formed. A general method of achieving such a division is to use a diamond saw. In order to increase the utilization area of the wafer for available semiconductor dies, and thereby increase the yield of semiconductor dies per wafer, there are many ways to reduce the area on the semiconductor wafer that must be allocated to the saw path. Is desired. Laser technology offers the opportunity to reduce the size of dicing paths in semiconductor wafers.
[0004]
The use of an infrared laser, such as a Q-switch 1064 nm Nd: YAG laser, to laser silicon is well known to those skilled in the art. However, since silicon is a weak wavelength absorber at a wavelength of 1064 nm, significant problems have been encountered with laser dicing processes operating at or near this wavelength. Typically, it has been determined that silicon re-volumes along the wafer surface and cutting wall surface, thereby impairing cutting quality.
[0005]
U.S. Pat. Nos. 4,541,035 and 4,589,190 describe an acousto-optic Q-switched infrared (IR) Nd: YAG laser integrated with a model ESI Model 25 laser scribing system at a wavelength of 1064 nm. A method is disclosed for forming structural features in silicon devices using pulsed output. (See also TR Anthony's paper "Diodes Formed by Laser Drilling and Diffusion", pages 9154-9164 of the magazine "Applied Physics", Vol. 53, published December 1982.) US Patent No. No. 4,618,380 also discloses a method of manufacturing an imaging spectrometer by treating a silicon device with a laser.
[0006]
U.S. Pat. No. 5,543,365 discloses a laser intended to form polysilicon stripes on a silicon wafer using a pulsed output at a wavelength of 1064 nm and a pulse width greater than 4 nanoseconds, such as that produced by a Nd: YAG laser. A scribing device is disclosed. Alternatively, the U.S. patent discloses that a wavelength of 532 nm that is twice the frequency can be used.
[0007]
Lee and his colleagues are able to manufacture multi-chip modules in the paper "Excimer VS Nd: YAG laser Creation of Silicon Vias for 3D Interconnctions" used in the international symposium called "1992 IEEE / CHMT Int'l Electronics Manufacturing Technology Symposium". It has been reported that Nd: YAG laser wavelengths of 1064 nm and 532 nm are used to form holes in the surface of a silicon wafer for the purpose of making the holes. Lee et al. Also reported that when laser drilling (laser drilling) through-holes in silicon at a wavelength of 1064 nm, molten material often condenses on the walls of the holes when reaching a significant depth. I have. This apparent redeposition of silicon renders the holes unsuitable for other processing. Lee et al. Report the use of a double drilling process at a wavelength of 1064 nm to improve hole quality. Lee et al. Used a ramp to cut a 4 mil (~ 100 micron) diameter hole in silicon using a rotating lens offset with respect to the incoming laser beam. It discloses the use of a so-called double pulsed laser output at a wavelength of 532 nm resulting from a pump Q-switch Nd: YAG. Further, Lee et al. Report processing parameters used as 833 μJ per pulse with a pulse width of 70 nanoseconds and a pulse repetition frequency of 3 kHz. It was still observed that silicon was redeposited around the perforated hole or along the wall of the hole, and a chemical etching process was used to clean the hole.
[0008]
Lee et al. Further report the use of an excimer laser with a wavelength of 248 nm to drill holes in silicon. The sidewalls of the holes were reported to be extremely smooth due to the very high pulse energy employed. Lee et al. Report a pulse repetition frequency of 250 Hz, a focused spot size of 5 mils (about 125 μm), and an energy per pulse of 290 mJ for piercing a silicon wafer in 30 seconds. . Lee and colleagues compared this drilling time to the 3 seconds required to drill using their Nd: YAG trepanning technique using a wavelength of 532 nm. Lee et al. Propose a method of reducing the drilling time required to drill holes in silicon with a 248 nm excimer laser using projection technology. As those skilled in the art will recognize, such techniques will be reliable if an appropriate aperture mask is used for each pattern of holes to be formed using such techniques.
[0009]
In U.S. Pat. No. 5,870,421, Dahm discusses the problem of using near-infrared lasers for dicing silicon wafers. Dahm states that the main cause of poor cutting quality due to redeposition when using near-infrared lasers is to use laser pulse widths greater than about 1 nanosecond. Dahm further states that near-infrared lasers with pulse widths shorter than about 1 nanosecond should be used to resolve the deep absorption depth of near-infrared wavelengths in silicon, It can produce a surface plasma that can act as a superabsorbent layer. Dahm further notes that UV lasers cannot generate enough energy to process silicon at high speeds, and near-infrared lasers such as 1064 nm wavelength Nd: YAG lasers generate more energy than UV lasers. It states that near-infrared lasers are used in high-speed fields because of their ability to operate.
[0010]
In U.S. Pat. No. 5,593,606, Owen et al. Use a UV laser system to generate a laser output pulse within a parameter range that is advantageous for forming a hole through at least two layers of a multilayer device. State benefits. These parameters generally reduce the instantaneous pulse width to less than 100 nanoseconds, reduce the spot diameter of the spot area to less than 100 μm, and increase the average intensity or emission over the spot area when the repetition rate is greater than 200 Hz. Includes output pulses of non-excimer lasers (lasers other than excimer lasers) with illuminance greater than 100 mW.
[0011]
In U.S. Pat. No. 5,841,099, Owen et al. Vary the UV laser output within a range of parameters similar to those described above to produce different energy densities and process different materials. Owen et al. Change the intensity by changing the repetition rate of the laser to change the energy density of the laser spot irradiating the workpiece, or to change the spot size, or both. .
[0012]
In U.S. Pat. No. 5,751,585, Cutler et al. Disclose a high-speed, high-precision multi-stage positioning system that accurately and quickly positions various tools, such as positioning a laser beam against a target on a workpiece. are doing. Cutler et al. Employ a multi-rate positioner system that processes workpiece target positioning commands and translates them into commands for low and high speed positioners. These positioners move without stopping in response to the flow of positioning data. In one example, this technique allows a laser to micro-pattern small structural features on large workpieces, thereby increasing the throughput of laser micro-machined components.
Summary of the Invention
[0013]
An object of the present invention is to provide a semiconductor including any one or any combination of silicon, gallium arsenide (GaAs), silicon carbide (SiC), silicon nitride (SiN), and Ge: Si, and a semiconductor including such a semiconductor. Semiconductor processing including, but not limited to, photolithographic techniques and etching processes well known to those skilled in the art to include additional layers for the purpose of forming useful electronic and optoelectronic circuits on semiconductor substrates, including wafers. It is an object of the present invention to provide an improved method of using a laser to form micro-flow structural features on the processed material.
[0014]
It is another object of the present invention to provide a method as described above employing a reliable non-excimer UV laser that is operable to produce a high pulse energy output at a high pulse repetition frequency.
[0015]
SUMMARY OF THE INVENTION The present invention provides a method for directly and rapidly forming a pattern having structural features with dimensions less than 50 μm on a semiconductor workpiece using ablation with an ultraviolet laser. A combined beam positioner is used to rapidly position the focused output of a non-excimer UV laser capable of emitting high energy per pulse output at a high pulse repetition frequency to a workpiece. The patterns described above include the formation of columnar holes with very large aspect ratios, such as through holes or blind holes for connecting integrated circuits, or the curved or curved shape of a processed semiconductor die provided on a silicon wafer. Such as square singulation (cutting), microtub cutting to separate microcircuits formed in a semiconductor workpiece from a parent wafer, arrayed waveguide grating (AWG) or microelectronic machine system (MEMS) Include the formation of curved or square structural features in the optical waveguide, and the scribing of alignment marks, identification marks or other marks on the wafer surface.
[0016]
The present invention uses laser wavelengths shorter than 390 nm, and therefore, makes the light absorption coefficient of silicon 1000 times the light absorption coefficient at the 1064 nm wavelength used in U.S. Patent Nos. 4,541,035, 4,589,190 and 5,543,365. Larger than Q switch frequency triple Nd: YAG, Nd: YVO_FourAlternatively, a Nd: YLF diode pump laser is a suitable ablation UV power source. According to the laser optical system, a Gaussian spot size of about 10 μm is obtained. Alternatively, an optical system that produces a top hat beam profile can be used. Exemplary pulse energies for rapid ablation of silicon using this focused spot size are greater than 200 μJ per pulse at pulse repetition frequencies greater than 5 kHz, preferably greater than 15 kHz. Preferably, the laser pulse width measured at the full width at half maximum is less than 80 nanoseconds (ns).
[0017]
The advantage of using UV wavelengths is that spot sizes can be generated that are significantly smaller than those available with longer wavelength laser sources. The ability to form such small spot sizes allows for the formation of micro-dimensional structural features in silicon. For certain fixed spot sizes that can be achieved with conventional Gaussian focusing techniques, shortening the wavelength can increase the depth of focus at ultraviolet wavelengths to form structural features with increased aspect ratios.
[0018]
The present invention uses stray-reflective materials and employs novel fabrication techniques for the workpiece support structure, resulting in stray reflections of the UV treatment beam from the workpiece support structure, such as a wafer chuck. A method for reducing damage to a processed semiconductor workpiece is also provided.
[0019]
Other objects and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments when taken in conjunction with the drawings.
Detailed Description of the Preferred Embodiment
[0020]
FIG. 1 shows the light absorption coefficient of silicon as a function of wavelength. Referring to FIG. 1, silicon exhibits a very steep increase in light absorption coefficient at the wavelength of ultraviolet light. The present invention makes efficient use of laser wavelengths shorter than 390 nm, and takes advantage of the fact that the light absorption coefficient of silicon increases with ultraviolet light, efficiently erodes and removes silicon, thereby providing various effective patterns or structures. Is formed directly in silicon. This light absorption characteristic significantly reduces the region that is thermally adversely affected by ultraviolet light and makes silicon extremely easy to use, compared to a structure formed using a pulse output of 532 nm or 1064 nm wavelength as taught in the prior art. Erosion removal.
[0021]
FIG. 2 shows the light absorption coefficient of GaAs as a function of wavelength. Referring to FIG. 2, GaAs exhibits a very steep increase in light absorption coefficient at the wavelength of ultraviolet light. The light absorption coefficients of GaAs and silicon are very similar at 355 nm. GaAs is a key material in optoelectronic devices such as diode lasers and detectors.
[0022]
3 and 4 illustrate laser processing systems 10a and 10b, respectively, according to the present invention that employ a combined beam positioning system 30 with a wafer chuck assembly 140 that can be employed to erosion pattern microstructures on a semiconductor workpiece 12 with an ultraviolet laser. (These laser processing systems are typically shown at 10). Referring to these FIGS. 3 and 4, in a preferred embodiment of the laser system 10, Nd: YAG, Nd: YLF or Nd: YVO_FourA Q-switched diode pump (DP) solid-state (SS) UV laser 14, which preferably includes a solid-state laser material (lasant) such as This laser 14 is mainly a TEM₀₀UV laser with one or more laser pulses at a wavelength such as 355 nm (frequency tripled Nd: YAG), 266 nm (frequency quadrupled Nd: YAG) or 213 nm (frequency quadrupled Nd: YAG) having a spatial mode profile of The output 16 is preferably generated harmonically.
[0023]
Although a Gaussian function can be used to represent the irradiance profile of the laser output 16, those skilled in the art will recognize that most lasers 14^TwoIt is understood that it does not emit a full Gaussian output 16 having a value of = 1. Here, the Gaussian function is M^TwoIs preferably less than 1.3 or 1.2, but is used for convenience as including profiles that are about 1.5 or less.
[0024]
In a preferred embodiment, laser 14 comprises a Model 210-V06 Q-switched frequency tripled Nd: YAG laser marketed by Lightwave Electronics, which operates at about 355 nm. This laser is used in a Micro Via Drilling System, model number ESI Model 2700, marketed by Electro Scientific Industries, Inc. of Portland, Oregon. In another embodiment, to increase the pulse repetition frequency (PRF) and the energy per pulse, a Q-switched frequency doubling Nd of Model Model 210-V09 sold by Lightwave Electronics operating at about 355 nm. : YAG laser can be used. As will be apparent to those skilled in the art, other lasers can be employed and other wavelengths can be obtained from the other laser materials listed. Although the construction of the laser cavity, generation of harmonics, Q-switching, and positioning systems are all well known to those skilled in the art, some of these details will be introduced in the description of the preferred embodiment.
[0025]
The UV laser output 16 optionally passes through various well-known magnification and / or collimation optics 18, propagates along an optical path 20, and is directed by a beam positioning system 30. The system output pulse 32 illuminates a desired laser target location 34 on the workpiece 12. The beam positioning system 30 preferably has a translation stage positioner, which supports positioning mirrors 42 and 44 in any combination of, for example, X, Y and Z directions and a plurality of positions on the same or different workpieces 12. Preferably, at least two lateral translation stages 36 and 38 are employed to achieve rapid movement between the target positions.
[0026]
In a preferred embodiment, the translation stage positioner includes a Y-direction translation stage 36, which is typically moved along a rail 46 by a linear motor to support and move the workpiece 12, and typically along a rail 48 by a linear motor. The moved X translation stage 38 is an axis separation system adapted to support and move the high-speed positioner 50 and its associated focusing lens. The dimension in the Z direction between the X-direction translation stage 38 and the Y-direction translation stage 36 may also be adjustable. The positioning mirrors 42 and 44 align the optical path 20 via any diverter between the laser 14 and a high speed positioner 50 located along the optical path 20 (alignment process). The high-speed positioner 50 may employ, for example, a high-resolution linear motor or a pair of galvanometer motors capable of performing one or repeated processing operations based on given inspection data or design data. The X and Y translation stages 38 and 36 and the high-speed positioner 50 can be controlled and moved independently of each other or cooperatively in response to panelized or non-paneled data. .
[0027]
High-speed positioner 50 also preferably includes a vision system that can be aligned with one or more reference points on the surface of workpiece 12. Beam positioning system 30 may employ a conventional vision or beam-work alignment system known to those skilled in the art, which operates via off-axis to objective 36 or another camera. In one embodiment, the alignment between the laser system 10 and a target location 34 on the workpiece 12 is implemented using an HRVX vision box using freedom library software in a positioning system 30 marketed by Electro Scientific Industries. Execute Other suitable alignment systems are commercially available. The alignment system preferably employs bright field, on-axis illumination, especially for specular workpieces such as wrapped or polished wafers.
[0028]
In addition, beam positioning system 30 determines Abbe errors due to pitch, yaw or roll sway of X and Y translation stages 38 and 36 that are not indicated by an on-axis position indicator such as a linear scale encoder or laser interferometer. However, it is also preferable to employ a non-contact type small displacement sensor. The Abbe error correction system can be calibrated against an accurate reference gauge such that the correction does not depend on the absolute accuracy of the sensor reading, but only on small changes detected in the sensor reading. Such Abbe error correction systems are described in detail in WO 01/52004 and US Patent Publication No. 2001-0029674. The relevant portion of US Patent Application Serial No. 09 / 755,950, which corresponds to this US Patent Publication, is incorporated by reference.
[0029]
Many variations of the positioning system 30 are well known to those skilled in the art, and several embodiments of the positioning system 30 are described in detail in US Pat. No. 5,751,585. A micro via drilling system, model number ESI Model 5320, marketed by Electro Scientific Industries, Inc. of Portland, Oregon, is a preferred configuration of the positioning system 30 and is used for laser drilling of resin-coated copper packages for the electronics industry. Other suitable positioning systems may be employed such as model numbers 27xx, 43xx, 44xx or 53xx manufactured by Electro Scientific Industries, Inc. of Portland, Oregon. Some of these positioning systems, which use an XY linear motor to move the workpiece 12 and an XY translation stage to move the scan lens, are cost-effective positioning systems for performing long linear cuts. is there. One of ordinary skill in the art would instead employ a system having a single XY translation stage to position the workpiece relative to a fixed beam position and / or a fixed galvanometer for beam positioning. It is clear that you can do that. Such a system uses a toolpath file that dynamically positions the focused output pulse 32 of the UV laser system at high speed, producing various useful patterns that can be periodic or non-periodic. Those skilled in the art will recognize that programming is possible. Those skilled in the art will also appreciate that doing so provides many advantages over the above-mentioned proposal by Lee et al. Of forming holes (via holes) in silicon using a projection imaging apparatus. It has recognized.
[0030]
An optical laser power controller 52, such as a half-wave plate polarizer, can be located along the optical path 20. Further, one or more beam detectors 54, such as photodiodes, may be located downstream of the laser output controller 52 so as to be aligned with the positioning mirror 44, which is partially transparent to the wavelength of the laser output 16. it can. The beam detector 54 is preferably combined with beam diagnostic electronics that produces a signal that alters the effect of the laser power controller 52.
[0031]
Referring to FIG. 4, a laser system 10b employs at least two lasers 14a and 14b, respectively, emitting laser outputs 16a and 16b, respectively, that are laterally linearly polarized, and these laser outputs are coupled to reflectors 42a and 42b, respectively. Is preferably propagated along the optical paths 20a and 20b. An optional wave plate 56 can be arranged along the optical path 20b. Preferably, the reflector 42a is a polarization sensitive beam combiner, located along both optical paths 20a and 20b, and combines the laser outputs 16a and 16b to propagate along the common optical path 20.
[0032]
Lasers 14a and 14b can be the same or different types of lasers, and can produce laser outputs 16a and 16b of the same or different wavelengths. For example, laser output 16a may have a wavelength of about 266 nm and laser output 16b may have a wavelength of about 355 nm. As will be apparent to those skilled in the art, the lasers 14a and 14b can be arranged side by side or one above the other, both of which can be mounted on one translation stage 36 or 38. The laser system 10b is capable of producing a laser output pulse 32b with very high energy. A particular advantage of the configuration shown in FIG. 4 is that the combined laser output with increased energy per pulse can be directed onto the workpiece, and such a laser output can be delivered from a typical single laser head. It is difficult to produce. Increasing the energy per pulse in this manner is particularly advantageous for eroding deep trenches or deep cylindrical holes in thick silicon wafers.
[0033]
Despite the substantially circular shape of the laser output pulse 32, an optional imaging optics module 62 spatially filters out residual astigmatism or unwanted beam characteristics such as ellipses and other shape characteristics. Beam shape quality can be improved. Referring to FIG. 5, the imaging optics module 62 is positioned at or near the optical waist formed by the optical element 64, the lens 66, and the optical element 64, and includes any unwanted side lobes of the beam. Preferably, an aperture mask 68 is provided to block the peripheral portion and subsequently image a precisely shaped spot profile on the workpiece. In the preferred embodiment, the optical element 64 is a focusing lens and the lens 66 is a collimating lens to provide flexibility in the configuration of the laser system 10.
[0034]
By varying the size of the aperture, the sharpness of the edge of the spot shape can be controlled, resulting in a smaller and sharper edge beam intensity profile, thereby increasing alignment accuracy. Further, with this configuration, the aperture can be made exactly circular or have a square, elliptical or other non-circular shape that can be aligned parallel or perpendicular to the cutting direction. The aperture of the aperture mask 68 can optionally be flared outward on its light exit side. In the imaging optics module 62, the aperture mask 68 may have a UV-reflective or UV-absorbing material, such as sapphire or UV-grade quartz glass coated with a multi-layer, highly UV-reflective coating or other UV-resistant coating. It is preferable to form the aperture mask 68 using a suitable dielectric material. As will be apparent to those skilled in the art, the aperture mask 68 can be used without the optical elements 64 and 66.
[0035]
In another preferred embodiment, the optical element 64 has one or more beam-shaping elements near the aperture mask 68 downstream of the optical element 64, such that the laser-shaping element emits a laser pulse having an original Gaussian irradiance profile. It converts to a shaped (and focused) pulse having a substantially uniform "top hat" profile or especially a super Gaussian irradiance profile. Such a beam shaping element may have an aspherical optical system or a diffractive optical system. In the preferred embodiment, lens 66 has imaging optics effective to control beam size and divergence. As will be apparent to those skilled in the art, one or more lens elements for imaging may be employed. Further, it will be apparent to those skilled in the art that the shaped laser output can be employed without using the aperture mask 68.
[0036]
In a preferred embodiment, the beam shaping element comprises a diffractive optical element (DOE) that can achieve high efficiency, high accuracy and complex beam shaping. The beam shaping element not only converts the Gaussian irradiance profile to a substantially uniform irradiance profile, but also focuses the shaped output to a particular spot size. Preferably, the diffractive optical element DOE is one, but as will be apparent to those skilled in the art, the diffractive optical element DOE may be a plurality of separate optical elements such as a phase plate and a conversion element disclosed in US Pat. No. 5,864,430. Devices. The U.S. patent also discloses a technique for designing a diffractive optical element DOE for beam shaping purposes. The shaping and imaging techniques described above are described in detail in WO 00/73013. The relevant part of US patent application Ser. No. 09 / 580,396 corresponding to this international publication is incorporated by reference.
[0037]
For the purpose of increasing the flexibility of the dynamic range of energy per pulse, a fast response amplitude control mechanism such as an acousto-optic modulator or an electro-optic modulator can be employed to modulate the pulse energy of successive pulses. . The pulse energy of successive pulses can be changed by increasing or decreasing the pulse repetition frequency instead of or in combination with the high-speed response amplitude control mechanism. FIG. 6 shows a characteristic relationship between the pulse energy and the pulse repetition frequency (PRF) of the laser 14 employed during the practice of the present invention. As shown in FIG. 6, a pulse energy larger than 200 μJ can be obtained from the laser “Lightwave 210-V06”. Further, the characteristic relation between pulse energy and PRF for other lasers “Lightwave 210-V09L” and “Lightwave 210-V09H” is also shown. As will be apparent to those skilled in the art, FIG. 6 illustrates the above-described principle, and variations of the laser system 10 may vary the characteristic relationship between pulse energy and pulse repetition frequency in the art.
[0038]
The performance characteristics described above of the UV laser system 10 can be used to rapidly fabricate micron-scale structural characteristics by laser ablation of semiconductors, particularly silicon. The formation of these structural features includes the formation of a cylindrical hole 100 that has fully penetrated or partially penetrated the silicon or other silicon workpiece 12 and has a very high aspect ratio and a silicon wafer or The formation of fully penetrated or partially penetrated grooves of complex geometry for the purpose of singulating (cutting) the processed semiconductor die on the silicon workpiece 12 and the microminiature formed in the silicon Includes, but not limited to, the formation of microtub structures that separate circuits from the parent wafer, the formation of structures on the AWG and / or the formation of laser singulation, and the formation of structures in MEMS. It is not limited. Further, the present invention facilitates the formation of structural features without causing significant lip formation due to melting, significant slag formation, and peelback of structural feature edges.
[0039]
FIG. 7 shows a 0.5 μm thick SiO._TwoA cylindrical hole formed by patterning by ultraviolet ablation on a silicon workpiece 12 such as a 500 μm thick intrinsic silicon substrate 70 covered with a surface stabilizing layer (not shown) is shown. As will be apparent to those skilled in the art, the thickness of the silicon workpiece and the surface stabilization layer can vary.
[0040]
Cylindrical hole 100 positions laser target position 34 of silicon workpiece 12 in the focal plane of laser system 10 and directs a series of laser system output pulses 32 onto laser target position 34 on silicon workpiece 12. Patterning is preferred. In this example, the silicon workpiece 12 is moved in the X and Y axes to direct the laser system 10 to a computer programmed central target position 34 that is the desired position for the cylindrical hole 100. Each of a series of laser system output pulses 32 is incident on a programmed central target position 34.
[0041]
In the case of ablation patterning (herein referred to as punching) of a cylindrical hole 100 in a silicon workpiece with successive overlapping pulses, a suitable range including energy per pulse, pulse repetition frequency (PRF) and focused spot size. Synthetic processing parameters are particularly advantageous for rapidly punching effective cylindrical holes 100.
[0042]
In the punching process, the workpiece 12 is fixed in the X and Y directions and each successive output pulse 32 of the laser system is incident on a programmed central target position 34. In the case of the silicon patterning process by ablation of the present example, a suitable energy range per pulse is about 100 μJ to 1500 μJ, more preferably about 200 μJ to 1000 μJ, more preferably about 300 μJ to 800 μJ, and most preferably about 300 μJ to 800 μJ. This is a value exceeding 360 μJ. A preferred PRF range is from about 5 kHz to 100 kHz, more preferably from about 7 kHz to 50 kHz, and even more preferably from 10 kHz to 30 kHz. The preferred focused spot size range is from about 1 μm to 25 μm, more preferably from about 3 μm to 20 μm, and most preferably from about 8 μm to 15 μm. As will be apparent to those skilled in the art, the laser performance shown in FIG. 6 can achieve energy per pulse output at a PRF within the most preferred ranges described above. Specifically, by programming a micro via drilling system of model number ESI Model 2700 to operate with the most preferred processing parameters to form a cylindrical hole with a diameter of 35 μm in a 750 μm thick silicon wafer workpiece. 1. A processing capacity of forming 100 cylindrical holes per second is obtained.
[0043]
In another embodiment, the laser focus position is moved in the height direction Z in response to each successive laser system output pulse 32, and the laser focus is sequentially positioned deeper in the silicon workpiece 12, thereby: Ensure that the focused spot is held in a position that more closely matches the rest of the silicon surface.
[0044]
In a preferred embodiment, the cylindrical hole 100 is formed by using approximately 100 successive output pulses 32 of the laser system using the output pulse energy from the laser 14 with an energy greater than 300 microjoules (μJ). It has completely penetrated the thickness 102 of the workpiece 12. The output pulse 32 of the laser system has its focused spot size (1 / e^Two) A diameter of about 12 μm is incident on the processing surface. The columnar hole 100 obtained in this example is typically about 20 μm in top opening diameter (d_t) 104 and an exit diameter (d_b), Whereby the cylindrical hole as the through hole has an aspect ratio of about 30: 1 and a taper angle of the hole of 0.4 °.
[0045]
As will be appreciated by those skilled in the art, the exact values of energy per pulse, focused spot size, and number of pulses required to effectively form a high quality cylindrical hole 100 in silicon are determined by the silicon workpiece 12. Thickness 102 and a coating layer (an example is SiO_Two) Can be varied depending on the relative thickness and composition and the exact UV wavelength employed. For example, to form a cylindrical through-hole in silicon for use as a point of direct conductive connection of an integrated circuit patterned on a silicon semiconductor die to a printed circuit, the silicon may be, for example, only 50 μm thick. Can be thick. In this example, only about 10 pulses need be used to form the desired cylindrical through-hole 100. One of ordinary skill in the art can form a cylindrical hole (blind via) that does not completely penetrate the entire thickness 102 of silicon by appropriately selecting the parameters described above.
[0046]
As will be apparent to those skilled in the art, such cylindrical holes formed in silicon with a high aspect ratio and a very small taper angle are extremely advantageous for the packaging and interconnecting fields of electronic devices. In addition, one or more groups of these small through-hole cylindrical holes 100 may be located near the periphery of the workpiece 12, circuit or semiconductor die, or on a top surface in a scribe, slice, or dicing passage. The rear or bottom surface of the workpiece 12 can be accurately aligned with the structural features on the top surface. Such alignment facilitates backside processing such as laser scribing or laser sawing to increase processing speed or performance. Wafer slicing or dicing techniques on the front and / or back side are described in U.S. patent application Ser. No. 09 / 803,382, filed Mar. 9, 2001, and U.S. Pat. It is described in detail in provisional application No. 60 / 301,701.
[0047]
FIG. 8 shows a state where the groove 110 is patterned on the silicon workpiece 12 by ultraviolet ablation. The groove 110 places the silicon workpiece 12 at the focal plane of the laser system 10 and causes the beam positioning system 30 to move the silicon workpiece 12 along its X and / or Y axis while the series of overlapping series. Preferably, patterning is achieved by directing successive laser system output pulses 32 to the silicon workpiece 12.
[0048]
In the case of a patterning process by ablation for forming a groove in silicon, a preferable energy range per pulse is about 100 μJ to 1500 μJ, more preferably about 200 μJ to 1000 μJ, further preferably about 300 μJ to 800 μJ, and most preferably. This is a value exceeding about 360 μJ. A preferred PRF range is from about 5 kHz to 100 kHz, more preferably from about 7 kHz to 50 kHz, and even more preferably from 10 kHz to 30 kHz. The preferred focused spot size range is from about 1 μm to 25 μm, more preferably from about 3 μm to 20 μm, and most preferably from about 8 μm to 15 μm. The preferred bite size range is about 0.1 μm to 10 μm, more preferably about 0.3 μm to 5 μm, and most preferably about 0.5 μm to 3 μm. The byte size can be adjusted by controlling the speed of one or both stages of the laser beam positioning system and adjusting the repetition rate of the laser and the speed of movement relative to the firing of the laser.
[0049]
In a preferred embodiment, the output pulse energy from the laser 14 of about 360 μJ is used and a 180 μm thickness is achieved by passing 180 times over the workpiece 12 at a stage speed of 10 mm / sec using a 1 μm byte size. SiO_TwoA straight groove 110 is formed by completely penetrating 750 μm thick intrinsic silicon covered with a surface stabilizing layer. These laser pulses have a focused spot size (1 / e^Two) With a diameter of 12 μm, the light is incident on the processing surface. As will be appreciated by those skilled in the art, the programming of the toolpath file used by the positioning system 30 and the laser system 10 to position the silicon workpiece 12 along the X and Y axes during processing may result in square, rectangular, elliptical, and spiral shapes. Alternatively, various patterns of variable geometric shapes can be created, including, but not limited to, any combination of these. In the case of laser cutting, it is preferred to align the beam positioning system 30 with a typical typical saw cutting or other criteria or pattern on the wafer surface. If a notch is already mechanically formed in the wafer, alignment to the cutting edge is preferred to eliminate sawing and alignment errors.
[0050]
The material that is destroyed by laser cutting (the cut width is smaller than 50 μm, preferably smaller than 25 μm) is smaller than the material that is destroyed by mechanical cutting (slicing lane is about 300 μm and dicing path is about 150 μm). Also, the devices on the wafers can be manufactured very close to each other, and thus more devices can be manufactured on each wafer. Therefore, the laser cutting process minimizes the line pitch and the device pitch.
[0051]
The elimination of mechanical cutting also simplifies the manufacture of the device on the workpiece 12. In particular, mechanical cutting exerts large mechanical stresses on the devices, which may cause them to be displaced from their carriers. To avoid losing rows, the device manufacturer may employ a strong adhesive or epoxy between the rows and the carrier. Any laser treatment significantly reduces the requirements on the mechanical strength of the adhesive used to secure the rows on the carrier. Thus, laser cutting eliminates the need for the strong adhesives or epoxy resins used to secure the rows to the carrier and the strong chemicals needed to remove them. Instead, the stripping time can be reduced, and in some cases the exposure time to corrosive chemicals can be reduced, making it easier to strip and adaptable to UV laser treatment, significantly reducing the risk of equipment damage. The adhesive may be selected so as to increase the yield.
[0052]
Laser row slicing reduces row bending. The reason is that laser slicing does not exert a large mechanical stress unlike mechanical slicing. However, if row bends or other row defects appear, the rows are diced (and again sliced) with a laser and, in the case of critical equipment, the equipment required between rows for mechanical dicing. These defects can be compensated for without being related to the alignment of the device. For convenience, it is common to use the term "(through) cutting" to include slicing (often associated with row separation of wafers) or dicing (often associated with singulation of parts from rows of wafers). Alternatively, slicing and dicing can be used interchangeably in the context of the present invention.
[0053]
Because the beam positioning system 30 can perform alignment with respect to the through-hole 100 or reference, the laser system 10 can process each row and / or each device independently. For diagonal rows, the laser spot provides the desired position relative to the outer edge of the device that translates the stage and / or beam between each cutting to obtain the desired rectangular or curvilinear waveform pattern. Thus, cross cutting can be performed across an oblique line. Thus, laser dicing could compensate for row fixing defects and protect all rows of equipment that could be destroyed by mechanical dicing.
[0054]
The throughput of UV laser cutting on silicon and similar materials can be increased by dividing the long cutting path into shorter segments. For cutting through-holes or grooves in thick silicon, these segments are preferably, for example, in the range of about 10 μm to 1 mm, more preferably in the range of about 100 μm to 1000 μm, most preferably Is in the range of 200 μm to 500 μm. The laser beam scans for a predetermined number of passes in a first short segment, then moves to a second short segment and scans for a predetermined number of passes in this second short segment. The byte size, segment size, and segment overlap amount can be adjusted so that the groove backfill amount and the like are minimized.
[0055]
FIG. 9 shows a simplified example of a segmented cutting profile 112a. Referring to FIG. 9, for convenience, the cutting path direction is from left to right, and the individual cutting segments 116k₁~ 116r_Three(Generally cutting segment 116) shows a cutting profile 112a formed from right to left. Cutting segment 116k₁~ 116r_ThreeAre shown in parallel in FIG. 9 for convenience, these cutting segments 116k₁~ 116r_ThreeAre actually collinear. FIG. 9 shows a plurality of segment sets 114a, each set having an initial segment 116k and a plurality of gradually increasing and overlapping segments 116m-116r, which are in alphabetical order. Processing is preferred. Each set 114a is preferably processed to a selected intermediate depth or a completely penetrating cutting is formed before the next set is processed. Although only five overlapping segments are shown for each set 114a, any number of overlapping segments required as appropriate for the intended material thickness can be employed, especially in sequential order. It will be apparent to those skilled in the art that the increase in length can be small. It will also be apparent to those skilled in the art that any or all of the segments 116 used in the cutting profile 112a may be processed bidirectionally, rather than being processed unidirectionally as shown in FIG.
[0056]
FIG. 10 shows a simplified example of a segmented cutting profile 112b, which is somewhat similar to profile 112a. Referring to FIG. 10, the profile 112b starts from the same segment set 114a that starts the profile 112a. However, segment set 114b does not have segment 116k, and segment set 114b overlaps the previously processed segment set by 60% so as to increase sequentially. In this example, the segment 116k₁Is cut in 30 passes, and the length is set to 200 μm. Next, segment 116m₁Was cut in 6 passes (1/5 of 30 passes) and its length was 240 μm (200 μm and segment 116 k₁(Sum of 2/5 of the length). Next, the segment 116n₁Is cut in six passes and its length is 280 μm (200 μm and segment 116 k₁(Sum of 2/5 of the length). This procedure is continued until the predetermined segment set 114b is completed. In this example, the dicing speed may be 8.5 mm / min or more.
[0057]
Real-time monitoring may also be employed to reduce the risk of rescanning portions of the cutting path where cutting has already been completed. Further, the polarization direction of the laser beam can be corrected according to the cutting direction, so that the processing capability can be further enhanced. These segmented cutting techniques are disclosed in US Provisional Application No. 60 / 297,218, filed Jun. 8, 2001.
[0058]
Another application of the patterning method by ultraviolet ablation of the present invention is to form a MEMS (micro electronic machine system) device 120. FIG. 11 diagrammatically shows a patterning method of the MEMS device 120 by ultraviolet ablation. In one preferred embodiment, the MEMS device 120 is patterned to form through grooves 122a, 122b, 122c, 122d, and 122e (typically referred to as grooves 122) in silicon using the methods described above. As will be apparent to those skilled in the art, the computer control of the X and / or Y axis of the laser positioning system 30 causes the directional laser system output pulses 32 to be directed toward the work surface. The pulses allow the formation of patterns that represent any complex curvilinear geometry. By using this control ability in combination with a patterning method by ultraviolet ablation, it is possible to form a complicated curved pattern in silicon that is effective for efficiently manufacturing various MEMS devices 120. FIG. 11 also shows a square hole formed by a pattern of adjacent grooves.
[0059]
Yet another application of the ultraviolet ablation patterning method of the present invention is in processing optical integrated circuits such as arrayed waveguide grating (AWG) devices 130 formed on a semiconductor wafer workpiece 12. FIG. 12 diagrammatically shows a patterning method of the AWG device 130 by ultraviolet ablation. In one preferred embodiment, the AWG 130 was patterned using the method described above, for example, to form a curved groove 132 in silicon having portions 132a, 132b, 132c, 132d, and 132e. Although the grooves 132 are shown as symmetric, it will be apparent to those skilled in the art that by controlling the X and / or Y axis of the laser positioning system 30, the directional laser system can be controlled. With the output pulses 32 directed at the work surface, the overlapped pulses 32 allow the formation of patterns that represent any complex curvilinear profile or geometry. By using this control ability in combination with a patterning method by ultraviolet ablation, it is possible to form a complicated curved pattern in silicon that is effective for efficiently manufacturing various AWG devices 130.
[0060]
It is not advantageous to employ a conventional metal chuck, such as formed from aluminum, to penetrate silicon workpiece 12. The reason for this is that the reflectivity of these conventional metal materials is high in ultraviolet light, which may introduce backside damage to the silicon workpiece 12. After the penetrating process was completed, a remarkable trace of backside damage around the cylindrical through hole 100 or the through groove 110 due to the reflected energy generated from the top of the metal chuck was confirmed by an experiment. However, unexpectedly, no backside damage was found near the cylindrical through-hole 100 or the through-groove 110 formed on the reference hole (tooling hole) of the metal chuck top.
[0061]
FIG. 13 diagrammatically shows a chuck assembly 140 in which the silicon workpiece 12 is positioned to perform the penetrating process using a patterning method by ultraviolet ablation. The chuck assembly 140 preferably has a vacuum chuck base 142, a chuck top 144, and an optional holding carrier 146. The vacuum chuck base 142 is preferably formed from a conventional metal material and is preferably bolted to an additional plate 148 (FIG. 4). Plate 148 is adapted to be easily connected to and / or separated from at least one of stages 36 and 38. The engagement mechanism is preferably mechanical, may have opposing grooves and ridges, and may have a locking mechanism. As will be apparent to those skilled in the art, the base 142 may be secured directly to the stage 36 or 38.
[0062]
The chuck top 144 is preferably formed from a dielectric material having low reflectivity at the ultraviolet wavelength selected for the particular patterning field. In a preferred embodiment employing a 355 nm output from a frequency tripled Q-switched diode pumped Nd: YAG laser, the UV transparent chuck top 144 is made of UV or excimer grade quartz glass, MgF_TwoOr CaF_TwoFormed from In another example, or in addition to the above, the UV transparent chuck top 144 may be liquid cooled to help maintain the temperature stability of the silicon workpiece 12. As will be apparent to those skilled in the art, quartz glass is an ultraviolet transparent material consisting of amorphous silicon dioxide, consisting of a chemical bond of silicon and oxygen.
[0063]
Referring again to FIG. 13, a holding carrier 146 can be placed on the chuck top 144 for the purpose of supporting the silicon workpiece 12 and holding it after patterning by ultraviolet ablation. Preferably, the holding carrier 146 is also formed from an ultraviolet transparent material to prevent backside reflection from damaging the workpiece 12 being penetrated. The holding carrier 146 is preferably machined to have a shallow recess for receiving the processed silicon workpiece 12 after the penetrating operation.
[0064]
In another example, chuck top 144 or holding carrier 146 is formed from a UV absorbing material such as Al or Cu, and laser system 10 has a tool path file of a pattern of shallow recesses to be formed in workpiece 12. Can be used to cut the corresponding pattern into the material of the chuck top 144 or the holding carrier 146. These recesses, for example, correspond to intentionally drilled holes or edge patterns to prevent backside damage to the workpiece 12 during the through-cutting process. Further, any debris debris resulting from the process can be contained in a recess remote from the back surface of the workpiece 12. In one preferred embodiment, the pattern of shallow recesses has dimensions that are slightly larger than the dimensions of the workpiece 12 after processing, so that the processed workpiece 12 can fit within the recesses of the holding carrier 146. To do. In another example, the holding carrier 146 is formed from an ultraviolet transparent material by other means, such as an optical manufacturing or etching process, after which the holding carrier is aligned and secured on the chuck top 144. The chuck assembly 140 of the example described above may be effectively applied to UV piercing other materials such as polyamide.
[0065]
As will be apparent to those skilled in the art, purge gases such as nitrogen, argon, helium, and dry air can be effectively used to help remove waste fumes from the workpiece 12. Such a purge gas may be exhausted to the immediate vicinity of the work surface using an exhaust nozzle attached to the laser system 10.
[0066]
In order to improve the surface quality of the silicon workpiece 12 treated using the patterning method by ultraviolet ablation, the treated workpiece is treated using an ultrasonic bath containing water, acetone, methanol and ethanol (but not limited thereto). 12 can be washed. As will be apparent to those skilled in the art, cleaning the treated workpiece 12 in hydrofluoric acid can be beneficial in removing unwanted oxide layers.
[0067]
While most of the foregoing has been directed toward processing silicon and GaAs, the methods described above generally apply to other semiconductors used as a substrate 70 for the workpiece 12, such as SiC, SiN or indium phosphide. Can.
[0068]
It is obvious that the present invention is not limited to the above-described embodiments, but can be variously modified.
[Brief description of the drawings]
[0069]
FIG. 1 is a graph showing the light absorption coefficient of silicon as a function of wavelength.
FIG. 2 is a graph showing the light absorption coefficient of gallium arsenide (GaAs) as a function of wavelength.
FIG. 3 is a simplified diagrammatic perspective view of a preferred laser system for patterning microstructures in semiconductors using ultraviolet laser ablation according to the present invention.
FIG. 4 is a simplified diagrammatic perspective view of another preferred laser system for patterning microstructures in semiconductors using ultraviolet laser ablation.
FIG. 5 is a simplified diagram illustrating an imaging optical module that can be used in a laser system for patterning microstructures in a semiconductor using ultraviolet laser ablation.
FIG. 6 is a graph illustrating the characteristic relationship between pulse energy and pulse repetition frequency of a laser (a high average power diode pumped 355 nm laser) used during the practice of the present invention (patterning a semiconductor by ablation).
FIG. 7 is a diagram showing a state where a cylindrical hole is patterned in silicon by ultraviolet ablation.
FIG. 8 is a diagram showing a state in which a groove pattern is patterned in silicon by ultraviolet ablation.
FIG. 9 is a simplified diagram showing an example of a segmented cutting profile for performing long cutting in a semiconductor material.
FIG. 10 is a simplified diagram showing another example of a segmented cutting profile for performing long cutting in a semiconductor material.
FIG. 11 is a diagram showing patterning of a MEMS device on a semiconductor wafer by ultraviolet ablation.
FIG. 12 is a diagram showing a state in which an AWG device is patterned on a semiconductor wafer by ultraviolet ablation.
FIG. 13 is a diagram illustrating an ultraviolet transmissive chuck on which a semiconductor workpiece is placed during processing using a patterning method by ultraviolet ablation.

Claims (37)

In laser processing silicon, GaAs, indium phosphide or single crystal sapphire substrate,
Generating low and high speed motion control signals from a positioning signal processor;
Controlling a large relative motion range of the translation stage using a low speed positioner driver in response to the low speed motion control signal;
Controlling a small relative motion range of the high-speed positioner using a high-speed positioner driver in response to the high-speed motion control signal;
Generating a first laser system output having an output pulse energy greater than 200 μJ at a wavelength shorter than 400 nm;
Directing the first laser system output to a target location on the substrate, removing the substrate material at the target location with a first spot area less than 25 μm on the surface of the target material;
Generating a second laser system output having an output pulse energy greater than 200 μJ at a wavelength shorter than 400 nm;
Directing the output of the second laser system to hit a second target location with a second spot area less than 25 μm on the surface of the target material, the second spot area at least partially overlapping the first spot area; A laser processing method. In laser processing silicon, GaAs, indium phosphide or single crystal sapphire substrate,
Generating a first laser system output having an output pulse energy greater than 200 μJ at a wavelength shorter than 400 nm;
Directing the first laser system output to a target location on the substrate, removing the substrate material at the target location with a first spot area less than 25 μm on the surface of the target material;
Generating a second laser system output having an output pulse energy greater than 200 μJ at a wavelength shorter than 400 nm;
Directing the output of the second laser system to hit a second target location with a second spot area less than 25 μm on the surface of the target material, the second spot area at least partially overlapping the first spot area; Forming a through hole in the substrate having a thickness of at least 50 μm, and making an aspect ratio of the through hole greater than about 20: 1. 3. The laser processing method according to claim 2, wherein the laser system output has at least five laser system output pulses. 3. The laser processing method according to claim 2, wherein a laser system output is irradiated on a front surface of the substrate to form a through hole reaching the back surface, and the laser processing method further includes:
A laser processing method including a step of performing alignment of an apparatus for performing processing on a back surface of a substrate using characteristics of a through hole in the back surface of the substrate. 5. The laser processing method according to claim 4, wherein at least two through holes are formed, and alignment of the back surface of the substrate for another processing is performed using both of the through holes. 3. The laser processing method according to claim 2, wherein a laser system output is irradiated on the front surface of the substrate, a through hole reaching the rear surface is formed, and the substrate has a surface material that is almost non-reflective to the laser system output. Laser processing method supporting 7. The laser processing method according to claim 6, wherein the surface material of the chuck causes almost no laser damage to the back surface of the substrate. 7. The laser processing method according to claim 6, wherein the surface material of the chuck transmits the laser system output almost completely. 7. The laser processing method according to claim 6, wherein the surface material of the chuck exhibits substantially perfect absorbency at the wavelength of the laser system output. 3. The laser processing method according to claim 2, wherein a laser system output is irradiated on the front surface of the substrate to form a through hole reaching the rear surface, and the substrate including the surface material having the hole is supported by a chuck. And a laser processing method for performing a through-hole forming process on these holes. In laser processing silicon, GaAs, indium phosphide or single crystal sapphire substrate,
Generating a first laser system output having an output pulse energy greater than 200 μJ at a wavelength shorter than 400 nm;
Directing the first laser system output to a target location on the substrate, removing the substrate material at the target location with a first spot area less than 25 μm on the surface of the target material;
Generating a second laser system output having an output pulse energy greater than 200 μJ at a wavelength shorter than 400 nm;
Directing the output of the second laser system to hit a second target location with a second spot area less than 25 μm on the surface of the target material, the second spot area at least partially overlapping the first spot area; Forming a kerf whose size in the longitudinal direction is larger than the spot size. 12. The laser processing method according to claim 11, wherein a laser system output has a characteristic of suppressing formation of a lip due to melting. 12. The laser processing method according to claim 11, wherein a laser system output has a characteristic of suppressing slag formation. 12. The laser processing method according to claim 11, wherein a laser system output has a characteristic of suppressing peelback of an edge of a kerf. The laser processing method according to claim 11, further comprising:
Generating a sequential laser system output having an output pulse energy greater than 200 μJ at a wavelength shorter than 400 nm;
The sequential laser system output is directed to a sequential target location with a spot area less than 25 μm on the surface of the target material, the sequential spot areas each at least partially overlap the previous spot area. Forming a kerf. 12. The laser processing method according to claim 11, wherein the kerf has a curved profile. The laser processing method according to claim 11, further comprising:
Generating low and high speed motion control signals from a positioning signal processor;
Controlling a large relative motion range of the translation stage using a low speed positioner driver in response to the low speed motion control signal;
Controlling the small relative range of motion of the high-speed positioner using a high-speed positioner driver in response to the high-speed motion control signal to enable the curved profile of the kerf. 12. The laser processing method according to claim 11, wherein a deep kerf having a bottom is formed in the substrate, and the apparatus is separated by the deep kerf, but the substrate is kept sufficiently thick at the bottom of the deep kerf. And a laser processing method for dividing the apparatus by using the output of the laser system. 12. The laser processing method according to claim 11, wherein the substrate is supported by a chuck having a surface material that is substantially non-reflective to the laser system output. 20. The laser processing method according to claim 19, wherein laser damage to the back surface of the substrate is substantially suppressed by the surface material of the chuck. 20. The laser processing method according to claim 19, wherein the surface material of the chuck is substantially completely transparent to the laser system output. 20. The laser processing method according to claim 19, wherein the surface material of the chuck exhibits near perfect absorption at the wavelength of the laser system output. 12. The laser processing method according to claim 11, wherein the kerfs extend to penetrate the depth of the substrate, and the chuck has holes, and the forming process of the kerfs is performed on these holes. Laser processing method. In order to increase the processing capacity for cutting a workpiece having a silicon, GaAs, indium phosphide or single crystal sapphire substrate and having a substrate material depth of at least 300 μm,
Identifying a first feature on a first surface of the workpiece;
Alignment of a first target position of the laser system with respect to a first feature on the first surface, such that the first target position is adjacent to the intended side of the element of the workpiece on the first surface. Process and
Directing one or more first laser system outputs to linearly illuminate a first surface at a first target location to form a first kerf to a kerf depth less than the depth of the substrate material; When,
Aligning a second target position of the laser system with respect to a second feature on the first surface or the second surface, the second target position being close to the intended side of the workpiece element on the second surface; An alignment step of being in the same plane as the first target position;
Directing one or more second laser system outputs to linearly illuminate a second surface at a second target location, forming a second kerf in the same plane as the first kerf; Forming a through cut that defines the intended side of the device. 25. The method of claim 24, wherein the first and second features are laser drilled throughout the depth of the substrate material, and appear on both the first and second surfaces. A method for increasing the cutting capacity so as to have a through hole. 25. The method according to claim 24, wherein the substrate is supported by a chuck having a surface material that is substantially non-reflective to the laser system output. 25. The method according to claim 24, wherein the surface material of the chuck substantially suppresses laser damage to the back surface of the substrate. 25. The method of claim 24, wherein the surface material of the chuck is substantially completely transparent to the output of the laser system. 25. The method of claim 24, wherein the surface material of the chuck exhibits near perfect absorption at the wavelength of the laser system output. 25. The method according to claim 24, wherein the chuck has holes and the through-cutting is formed on these holes. In laser processing a silicon, GaAs, indium phosphide or single crystal sapphire substrate of a workpiece having first and second surfaces,
Generating low and high speed motion control signals from a positioning signal processor;
Controlling a large relative range of motion of a translation stage comprising or supporting a chuck having a surface material that is substantially non-reflective to the laser system output using a low speed positioner driver in response to the low speed motion control signal;
Controlling a small relative motion range of the high-speed positioner using a high-speed positioner driver in response to the high-speed motion control signal;
Generating a sequential laser system output having an output pulse energy greater than 200 μJ at a wavelength shorter than 400 nm;
Directing the sequential laser system output to a sequential target location with a spot area less than 25 μm on the first surface of the workpiece, each sequential area at least partially over the previous spot area; Wrapping to form a through-hole or a through-cut in the substrate without substantially damaging the second surface. 32. The laser processing method according to claim 31, wherein the surface material of the chuck is substantially completely transparent to the output of the laser system. 32. The laser processing method according to claim 31, wherein the surface material of the chuck exhibits near perfect absorption at the wavelength of the laser system output. A laser system for processing a silicon, GaAs, indium phosphide or single crystal sapphire substrate of a workpiece, comprising:
A low-speed positioner having a translation stage with or supporting a chuck having a surface material that is substantially completely non-reflective to the laser system output to achieve a large range of relative movement between the tool and the workpiece;
A high speed positioner that achieves a small range of relative movement between the laser system output and the workpiece;
A positioning signal processor for extracting low-speed and high-speed motion control signals from a positioning command;
A low-speed positioner driver that controls a large range of relative motion of the translation stage in response to a low-speed motion control signal;
A high-speed positioner driver that controls the relative movement of a small range of the high-speed positioner in response to the high-speed motion control signal;
A laser system for generating a laser system output. 35. The laser system of claim 34, wherein the surface material of the chuck is substantially completely transparent to the laser system output. 35. The laser system according to claim 34, wherein the surface material of the chuck is substantially completely absorbing at the wavelength of the laser system output. 35. The laser system of claim 34, wherein the high speed positioner driver facilitates the production of a kerf having a curved profile.