Patent Application
20070173075
1. Field of the Invention
This invention generally relates to laser processing systems and methods, including systems and methods for removing, with high yield, closely-spaced conductive link structures or “fuses” on a substrate of an integrated circuit or memory device.
2. Background Art
The following exemplary non-patent references relate to laser memory repair processes and interconnect technology:
Chapter 19 of [5] also shows various arrangements of links on die, typically groups of links having a pre-determined pitch. The links are generally arranged in rows and column. Sometimes the links are staggered as shown in
Reference [5] indicates designers would like to avoid adjacent link damage. Such damage was attributed to at least spot size, link width, and position error. The present trend is toward 1 micron pitch structures having link widths well below a visible wavelength of light (<0.4 μm, and below 0.1 μm).
Conventional near IR laser based systems, for instance those using 1-1.3 μm wavelengths, have limited process capability—no finer than about 2.0 μm pitch. The diffraction limited spot size and depth of focus (DOF) are two specific limiting factors. Now, as fuse pitches continue to decrease to about 1 micron, neighbor fuse damage is also major failure mode which further limits processing capability at long wavelengths. The benefit of reduced substrate damage is offset by such limiting factors.
Additional margin, so to avoid substrate damage or collateral link damage, may be provided for fine pitch by the shielding layers or other material modification, for instance as disclosed in EP published application No. 0902474, and U.S. Pat. Nos. 5,936,296; 6,057,180; 6,297,541; 6,320,243; 6,664,173; and 6,979,798. The links may have one or more passivation layers between the incident beam and the link. Similarly, there may be one or more metal or dielectric layers between the link and substrate. Link materials may be aluminum, copper, gold, polysilicon or other suitable materials.
Numerous memory devices include multi-level, stacked link structures having highly conductive aluminum lines, with overlying and/or underlying metal films.
The metal film materials may selected based on various physical properties, including optical properties. For example, TiN offers protection from oxidation and minimizes contact of the metal interconnect with SiO2. However, TiN is also useable as an anti-reflection coating (ARC) at certain wavelengths. For example, high absorption is advantageous in lithography steps for patterning of interconnects (metal lines). A standard UV wavelength of 266 nm is often used for the patterning.
U.S. Pat. Nos. 5,936,296 (the '296 patent) and 6,320,243 (the '243 patent) further disclose TiN, TiW, and Ti/TiN ARCs, various associated properties, and various link (fuse) structures. The benefits of ARC are recognized to provide for a reduction in laser energy. This in turn reduces stress on peripheral elements and can reduce adjacent (neighbor) link damage. Specific reference is made to at least cols. 3 and 9 of the '296 patent, and cols. 3, 6, and 7 of the '243 patent for further information.
An object of the present invention is to provide laser-based methods and systems for processing multi-material devices having conductive link structures.
In carrying out the above object and other objects of the present invention, a method of laser processing a multi-material device including a silicon substrate, conductive target and adjacent link structures and at least one inner dielectric layer which separates the link structures from the silicon substrate is provided. The method includes generating at least one focused laser pulse which has a predetermined visible or near UV wavelength long enough to sufficiently tolerate variations of at least one of the thickness and reflectance of a layer of the device or variations over a batch of the devices. The silicon substrate has a relatively high absorption coefficient at the predetermined wavelength. The at least one dielectric layer has a relatively low absorption coefficient at the predetermined wavelength. The method further includes applying the at least one focused laser pulse which has the predetermined wavelength into an approximate diffraction-limited spot during motion of the substrate relative to the at least one focused pulse. The spot has a 1/e2 spot diameter in a range of about 0.5-1.5 microns. The at least one focused laser pulse has an energy density over the spot sufficient to completely process the target link structure while avoiding undesirable change to the adjacent link structure, the substrate and any layers between the substrate and the link structures. The target link structure and the adjacent link structure have a pitch of about 2.0 microns or less.
The step of generating may generate a pulsed laser output having a wavelength below an absorption edge of the substrate and in the range of about 0.3-0.55 microns.
The step of applying may include the step of directing the pulsed laser output at the target link structure at an incident beam energy sufficient to completely process the target link structure.
The target link structure and the at least one laser pulse both have a position. The method may further include generating computer-controlled timing signals synchronized with the position of the at least one pulse relative to the position of the target link structure.
The step of generating computer-controlled timing signals may be based on the position of the at least one laser pulse relative to the position of the target link structure.
The method may further include providing an optical switch and switching the optical switch based on the timing signals to cause a plurality of focused laser pulses to be transmitted to the target link structure.
The step of generating may be performed with a pulsed laser subsystem having a near UV, blue or green wavelength.
The subsystem may include a frequency doubled or tripled MOPA.
The target link structure may have a relatively high absorption at the predetermined wavelength.
The pitch may be about 1.5 microns or less.
The diameter may be about 0.7 microns.
Energy delivered to the target link structure when the pitch is about 1-1.3 microns may be about 0.014 micro joules to less than about 0.055 micro joules over the 0.7 micron diameter.
Energy density over the diameter may be in a range of about 1 J/cm2 to about 20 J/cm2.
Further in carrying out the above object and other objects of the present invention, a system for laser processing a multi-material device including a silicon substrate, conductive target and adjacent link structures, and at least one inner dielectric layer which separates the link structures from the silicon substrate is provided. The system includes means including a pulsed laser subsystem for generating at least one focused laser pulse having a predetermined visible or near UV wavelength long enough to sufficiently tolerate variations of at least one of the thickness and reflectance of a layer of the device or variations over a batch of the devices. The silicon substrate has a relatively high absorption coefficient at the predetermined wavelength and the at least one dielectric layer has a relatively low absorption coefficient at the predetermined wavelength. The system further includes means for applying the at least one focused laser pulse which has the predetermined wavelength into an approximate diffraction-limited spot during motion of the substrate relative to the at least one focused pulse. The spot has a 1/e2 spot diameter in a range of about 0.5-1.5 microns. The at least one focused laser pulse has an energy density over the spot sufficient to completely process the target link structure while avoiding undesirable change to the adjacent link structure, the substrate and any layers between the substrate and the link structures. The target link structure and the adjacent link structure have a pitch of about 2.0 microns or less.
The means for generating may generate a pulsed laser output having a wavelength below an absorption edge of the substrate and in the range of about 0.3-0.55 microns.
The means for applying may include means for directing the pulsed laser output at the target link structure at an incident beam energy sufficient to completely process the target link structure.
The target link structure and the at least one laser pulse both have a position. The system may further include a computer programmed to generate timing signals synchronized with the position of the at least one pulse relative to the position of the target link structure.
The computer may be further programmed to generate the timing signals based on the position of the at least one laser pulse relative to the position of the target link structure.
The system may further include an optical switch and means for switching the optical switch based on the timing signals to cause a plurality of focused laser pulses to be transmitted to the target link structure.
The pulsed laser subsystem may have a near UV, blue or green wavelength.
The subsystem may include a frequency doubled or tripled MOPA.
The target link structure may have a relatively high absorption at the predetermined wavelength.
The pitch may be about 1.5 microns or less.
The diameter may be about 0.7 microns.
Energy delivered to the target link structure when the pitch is about 1-1.3 microns may be about 0.014 micro joules to less than about 0.055 micro joules over the 0.7 micron diameter.
Energy density over the diameter may be in a range of about 1 J/cm2 to about 20 J/cm2.
The multi-material device may include a multi-layer stack, the stack having at least one dielectric layer over one or more of the link structures.
The diffraction-limited spot may be centered about the target link structure to within about 0.15 μm, wherein damage to the adjacent link structure is avoided.
The laser pulses may be produced at a pulse repetition rate of about 70 KHz or greater.
The multi-material device may also include conductive link structures having a pitch of about 2.0 microns or greater, and wherein timing signals may adjust the speed of movement of the substrate based on the pitch of about 2.0 microns or greater so as to provide for an improvement in throughput.
The pulsed laser subsystem may include a diode-pumped, frequency-doubled laser. The laser may have an infrared (IR) fundamental wavelength and a minimum available pulse repetition rate of at least 50 KHz with available output energy of about 4 μJ or greater at the minimum available pulse repetition rate, residual IR of less than 1% of total power, peak-peak stability of about 5% or better, and output beam quality corresponding to M2 of about 1.1 or better.
The above object and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.
a and 3b are side cross-sectional views which illustrate examples of link structures and surrounding materials representative of various memory devices;
a-4e are side cross-sectional views which illustrate exemplary link structures of
a-6c are graphs which illustrate a relationship between dielectric layer reflectance and dielectric layer thickness at various wavelengths;
a and 8b illustrate top-view images of links processed with a laser spot size of 0.7 μm (1/e2 diameter); laser energies: (a) from 0.005 μJ to 0.045 μJ and (b) from 0.050 μJ to 0.090 μJ with a 0.005 μJ step, respectively;
a and 9b are SEMs which illustrate FIB images of laser-cut sites processed with 0.04 μJ at 0.7 μm 1/e2 spot in diameter; (a) top view of the processed fuses and (b) cross-sectional view;
a and 10b are graphs with curves which illustrate electrical measurement results of 300 links processed with 0.7 μm (1/e2 spot diameter); link pitch: 1.0 μm, (a) parallel structure for checking cut qualities and (b) serial structure for checking damages to adjacent link structures; and
a and 11b are graphs with curves which illustrate electrical measurement results (each set has 300 links) processed with 0.04 μJ and 0.7 μm 1/e2 spot in diameter; link pitch: 1.0, 1.1, 1.2 and 1.3 μm, (a) parallel structure for checking cut qualities and (b) serial structure for checking damages to adjacent link structures.
A method and system for processing very fine pitch link structures of a multi-material semiconductor memory device is disclosed. In at least one embodiment the method includes applying at least one laser pulse to a target link structure. The at least one laser pulse has a short wavelength below the absorption edge of the silicon substrate. The at least one laser pulse provides sufficient energy density over a spot size small enough to cleanly remove the link and avoid unacceptable damage to neighbor links. The energy density of the at least one laser pulse is also small enough to avoid unacceptable damage to the substrate, and to any functional layers between the link structure and the substrate.
A system for processing very fine pitch link structures of a multi-material semiconductor memory device is disclosed. In at least one embodiment the system includes a laser pumping source, a laser resonator cavity configured to be pumped by the laser pumping source, and a laser output system configured to produce a laser output from energy stored in the laser resonator cavity and to direct the laser output at the target structure on the silicon substrate in order to vaporize the target structure, at a wavelength below an absorption edge of the silicon substrate and in the range of about 0.3 to 0.55 microns. The silicon substrate is positioned beneath the target structure with respect to the laser output. The laser output system is configured to produce the laser output at an incident beam energy. The system also includes a computer programmed to generate computer-controlled timing signals synchronized with the position of the pulsed laser beam relative to the target structure, and an optical switch that is controllably switchable based on the timing signals so as to cause output pulses of the pulsed laser beam to be transmitted to the target structure. The incident beam energy at which the target structure is vaporized is reducible relative to an incident beam energy necessary to deposit unit energy in the target structure sufficient to vaporize the target structure at a higher wavelength below the absorption edge of the silicon substrate.
A method of processing very fine pitch link structures of a multi-material semiconductor memory device is disclosed. The method includes the steps of providing a laser system configured to produce a laser output at a wavelength below an absorption edge of the silicon substrate and in the range of about 0.3-0.55 microns, and directing the laser output at the target structure on the silicon substrate at the wavelength and at an incident beam energy, in order to vaporize the target structure. The silicon substrate is positioned beneath the target structure with respect to the laser output. The method also includes the steps of generating computer-controlled timing signals synchronized with the position of the pulsed laser beam relative to the target structure, and controllably switching an optical switch based on the timing signals so as to cause output pulses of the pulsed laser beam to be transmitted to the target structure. The incident beam energy at which the target structure is vaporized is reducible relative to an incident beam energy necessary to deposit unit energy in the target structure sufficient to vaporize the target structure at a higher wavelength below the absorption edge of the silicon substrate.
By way of example, specific reference is made to at least Col 3, Line 1-Col 4 Line 4 and corresponding figures of the '622 patent. A link blowing system is disclosed for short wavelength processing wherein coupling of energy into the target structure and substrate absorption are both considered at wavelengths where the substrate is not very transparent.
A method of processing very fine pitch link structures of a multi-material semiconductor memory device is disclosed In at least one embodiment the method may include laser processing a multi-level, multi-material device including a substrate, a conductive link and a multi-layer stack, the stack having at least two inner dielectric layers which separate the conductive link from the substrate is disclosed. The method includes: generating a pulsed laser beam having a predetermined wavelength less than an absorption edge of the substrate, the substrate having a relatively high absorption coefficient at the predetermined wavelength and the stack having a low absorption coefficient at the predetermined wavelength and including at least one laser pulse wherein at least reflections of the laser beam by the layers of the stack substantially reduce pulse energy density at the substrate relative to at least one other wavelength; and processing the conductive link with the at least one laser pulse wherein pulse energy density at the conductive link is sufficient to remove the conductive link while avoiding damage to the substrate and the inner layers of the stack.
By way of example, specific reference is made to at least the following sections of the '268 patent:
In at least one embodiment processing may be carried out a short visible wavelength. The visible wavelength may produce a larger process energy window relative to that achievable at a shorter UV wavelength.
Also, a preferred motion control system, including precision stage(s) for wafer motion, is disclosed in the '844 patent. Reference is generally made to
Further, the positioning accuracy of the at least one pulse relative to the link is sufficient to avoid the neighbor link damage, and will typically be about 0.15 μm or better (1 mean 1+3*sigma), at a typical 70 KHz link processing rate.
The commercially available model M-455 memory repair machine, available from the assignee of the present invention, includes an NdYVO4 short pulse laser system as generally shown in
In at least one embodiment of the present invention:
The laser output may be generated by a frequency doubled, diode-pumped, NdYVO4, solid state laser.
The frequency doubled output may produce a 532 nm wavelength.
The laser output may include at least one pulse having pulse width less than about 25 ns, for instance about 15-20 ns.
The laser output incident on the target structure may be focused into a spot having a 1/e2 spot diameter in the range of about 0.5-1.5 microns, for instance, about 0.7 μm.
The energy delivered to each target structure of a group of links having about 1-1.3 μm pitch may be about 0.015 μJ to less than 0.055 μJ over a spot size of about 0.7 μm, as measured at the 1/e2 diameter, with slightly larger energy for link pitch approaching 1.5 μm.
The energy density, over a 1/e2 diameter, may be in an approximate range of about 1 J/cm2 to less than 20 J/cm2, for processing of various fuse structures. Slightly larger energy may be used for link pitch approaching 1.5 μm.
Preferably the energy density will be less than about 5 J/cm2 over the 1/e2 spot diameter, and may be less than about 1 J/cm2 over the 1/e2 diameter.
Certain very fine pitch link structures, for instance the stacked structures shown in
A target structure may be a link having a width of about 0.1 μm or less, and spaced about 1-1.5 apart from one or more adjacent links, thereby corresponding to pitch of about less than 1.5 microns, for example 1 μm.
The links may be positioned relative to the at least one pulse with accuracy of 0.15 microns or better (3*sigma).
In at least one exemplary embodiment: the spot size is about 0.7 μm diameter (measured at the 1/e2 diameter); a single q-switched pulse having a pulse width about 15-20 ns is applied to the link, and the laser wavelength is 532 nm. The links are arranged with 1.5 micron pitch, and at least one dielectric layer separates the link and substrate.
The second harmonic of the 1.064 μm source, which yields a wavelength in the green portion (532 nm) of visible spectrum, with a near diffraction limited lens, can provide for a minimum 0.7 μm 1/e2 spot in diameter at focus. The arrangement provides the same approximate depth of focus (DOF) compared with IR at a spot size of 1.4 μm 1/e2 spot in diameter.
In one or more embodiments the laser may be a diode-pumped NdYVO4 laser with the following specifications:
Crystalaser is a supplier of diode-pumped, q-switched lasers.
In one alternative embodiment an output may be produced using a MOPA configuration as shown in the '458 patent with a frequency doubler in the optical path. The output may include a plurality of pulses having a square temporal pulse shape, or other suitable pulse shape.
In at least one embodiment the laser wavelength may be a non-standard laser wavelength in the range of about 400 nm -550 nm. Operation at wavelengths from about 400 nm to about 500 nm may be achieved by frequency tripling a laser having a wavelength in the range of 1.2 to about 1.55 μm.
In at least one embodiment the frequency tripled laser may include a MOPA. The MOPA may include a semi-conductor seed laser, fiber optic amplifier, and frequency tripler.
In another embodiment the laser wavelength may be a frequency tripled output of a near IR laser, in the range of about 0.3 μm to 0.4 microns, and above the absorption edge of an inorganic dielectric layer.
Further, in the wavelength range of blue through violet, there are many choices:
A. Solid State Lasers
(1) Similar wavelengths can be obtained from fiber or disk lasers through harmonics;
(2) Ti:sapphire laser tunable from 380-465 nm SHG of Ti:sapphire laser;
(3) Rare earth doped solid state or fiber lasers plus harmonics that will generate wavelengths in the 350-490 range. Many examples can be found in the literature.
B. Semiconductor Lasers
(1) The quest for a blue laser started with II-VI zinc-selenide compounds, but striking achievements have been made with wide-gap III-V nitride materials, which emit light with a much shorter wavelength. While the wavelength of blue laser is around 450 nm, that of GaN lasers is around 400 nm (from 380 to 450 nm);
(2) Use SHG lightwave guide element (like LiNbO3), a 425-nm laser can be obtained from an 850-nm diode laser.
C. Gas-ion Lasers
Wavelengths achievable with gas-ion lasers include 375, 420, 450, 514.5 nm.
Materials and Optical Properties:
a and 3b each illustrate a portion of a wafer having a link and surrounding materials.
a shows a conventional arrangement having a link and overlying passivation layer separated from the substrate by a single dielectric layer.
b shows another device structure with a link as in
Some link materials include a stack of conductive materials. The stack materials may be selected from various combinations of Aluminum, Copper, Gold, Tungsten, Titanium, Polysilicon, various refractory metals, metal nitrides, or other suitable materials.
As shown in
Sometimes one or more overlying passivation layers may be removed (etched) for link processing. As can be seen from
d shows an example of another link structure, in this case a Copper fuse. The graph shows absorption is maximized near a standard green wavelength of 532 nm. This type of link structure is typical of the Dual Damascene process as reference in the '268 patent and some non-patent references therein.
Optical properties of the Silicon substrate are also of general interest, and illustrated by two publications are cited herein:
Donald Rapp, “Thermo-Optical Properties of Silicon”
Haapalinna et. al., “Spectral Response of Silicon Photodiodes,”
Applied Optics, Vol 37, No. 4, 1 Feb. 1998
The publications are incorporated by reference in their entirety. Plots of spectral reflectance and absorption are shown, including results based on Si covered with SiO2. Spectral reflectance and absorption curves of Si have also been published in numerous other publications and handbooks.
Increased reflectance of Si at wavelengths below about 400 nm can also affect performance, and useful to consider for modeling and/or predicting link blowing performance at short wavelengths results. The Si absorption and reflectance increases as shown
The polarization sensitivity is interesting, particularly when the high N.A. of the beam delivery optics is considered. The '786 patent generally teaches adjustment of polarization to increase the energy processing window, including the upper end of the energy window to avoid neighbor link damage.
The increased reflectance at the UV wavelengths may also result in increased adjacent link damage of very fine pitch devices.
Manufacturing tolerances of various materials can limit yield at short wavelengths. The laser energy required for link processing may need frequent adjustment. At longer wavelengths the energy required for link processing is less sensitive to oxide thickness or other thickness variations and reflectance variations of the substrate.
Some test results indicated dielectric thickness variations can affect link processing performance at short wavelengths.
At least some data suggests operation at short visible wavelengths (e.g.: wavelengths greater than 400 nm) will provide for more consistent performance. For instance, visible wavelengths in the range of 400 nm-550 nm the reflectance and sensitivity to thickness is decreased while providing for decreased spot sizes for processing very fine pitch devices.
The '268 patent teaches at least one method and system for decreasing system sensitivity to such variations. Measurement of thickness and adjustment of laser power are disclosed in
The energy process window is a figure of merit used to characterize link processing results, a larger window provides increased process tolerance.
Each data point in
The Ehigh curve (Ehigh) indicates the maximum energy level that can be used to process each structure without any damage, and the results were determined based on the two failure modes. When the pitches are larger than 1.5 μm or so, Ehigh was limited by Si substrate damage (SUB DAMAGE curve) and neighbor fuse damage (NEIGH DAMAGE curve) occurred at higher levels. However, neighbor fuse damage occurred at lower energy levels than Si substrate damages with a decrease of pitch to less than 1.5 μm. In other words, neighbor fuse damages occurred at lower energy levels than substrate damages and limits the whole process window for tight pitch structures. Therefore, a smaller spot size is required in order to process tight pitch structures of 1.5 μm or less.
It is noted that this data was based on controlled, accurate alignments and the actual cross-over pitch of neighbor fuse to substrate damages at 1.5 μm will be likely even larger assuming a real production process. Lower corner cracking of aluminum link was not evaluated because the data was decided based on the results observed from the top view. However, the link structures were very thin relative to the link width and aspect ratio was less than one (1). Therefore, cracking at lower corners is unlikely and the data is considered to be valid. For further discussion of lower corner cracking see [2], Bernstein et al.
Short wavelength lasers, and reduced spot sizes, can reduce adjacent link damage. For an equivalent F # (number) and aperture objective lens, a shorter wavelength laser allows the laser beam to be focused to a much smaller spot. Furthermore, short wavelength lasers can create larger DOF than IR at the equivalent spot size. As is well known, a small spot and large DOF are both beneficial to the process of fine pitch metal link structures.
The following results show successful processing of metal fuse structures down to 1.0 μm pitch using a minimum 0.7 μm 1/e2 spot, 532 nm wavelength laser and employing FIB (Focused Ion Beam) image observations and electrical measurements.
The test wafer, with the aluminum lines, was fabricated using a standard two-level metal CMOS process for this particular short wavelength laser experiment. The metallization, used for this study, was sputtered Al (1% Si, 0.5% Cu) etched to form variously wide fuses and 0.6 μm thick lines. The Al lines were originally undercoated and overcoated with 0.05 μm thick TiN layer. However, an anti-reflection coating (ARC) over-coating TiN layer was etched away in order to optimize the fuse thickness to form 0.35 μm thick metal lines. During this etching process, surrounding SiO2 was recessed due to etch selectivity compared to aluminum. A passivation layer of 0.7 μm of Si3N4, covered the metallization for the purpose of reliability after the laser process.
Testing was carried out with on groups having 1.0 μm˜1.3 μm with a 0.1 μm step. Also, each pitch has 6 different fuse widths (0.1 μm˜0.6 μm with a 0.1 μm step). Therefore, there are a total of 24 different linear aluminum fuse structures. Each structure is designed to have two different formats; one is to check the cut quality (parallel) and the other is to check for any damages to adjacent structures in order to ensure the acceptability of the cut processing (serial). Electrical measurements were conducted after microscopic observations of the processed fuse structures.
The laser system used to perform these experiments was a GSI Group M455 laser processing system. The system employs a diode-pumped, Q-switched, frequency doubled Nd:YVO4 laser (532 nm) operated in the saturated single-pulse mode. Pulses, with lengths of approximately 19 ns in FWHM scale, were directed through focusing optics to produce a beam of 1/e2 diameter of approximately 0.7 μm spot at focus. The 3-sigma positioning accuracy of the laser system was approximately less than 0.15 μm.
For this experiment, three optimum energies for each structure (a nominal energy of the process window and slightly higher energies) were selected based on laser energy studies and irradiated on each structure.
An example of a laser energy process study is shown in
Laser energy studies were performed on all different structures and at 3 process energies, within the energy process window at a 0.7 μm 1/e2 spot, were selected for each structure based on the results. Each laser energy was used to blast two sets of 600 links (a parallel set of 300 links and a serial set of 300 links) in order to ensure cut quality and no damage to adjacent links, a critical parameter as mentioned earlier.
a and 9b show SEM and FIB cross-sectional images of the 1.0 μm pitched 0.3 μm wide aluminum fuses that were processed with a laser energy of 0.04 μJ and 0.7 μm 1/e2 spot in diameter.
Various metal structure designs and laser parameters were tried and the results were measured electrically to ensure the possibility of implementing 532 nm wavelength on very fine pitch metal structures.
All the data show around 100 G Ω that is well beyond the value for acceptable laser link processing. The authors believe that there is still a range for optimum link width depending on particular fuse designs and laser parameters, and in-depth study is being performed and will be presented in a later publication.
The resistances of a series of fuses (the serial structures), which are next to processed fuses, were also measured. The results from electrical measurements of the unprocessed links are in
Average electrical resistance values for all the processed link structures including the data of 1.0 μm pitch structures (presented in
Results in
Microscopic observations and electrical measurements show that a 532 nm wavelength laser is fully capable of processing certain very fine pitch metal link structures down to 1.0 μm without any changes in current IC fabrication processes. The advantages of the 532 nm laser include larger DOF with smaller spot size compared with the current IR lasers.
At the very fine scale susceptibility to Silicon substrate damage, adjacent link damage, and damage to functional circuitry should all be considered simultaneously. In order to maximize the energy window, optical properties of the device materials is to be considered for additional experiments with different devices and various of combinations of device material.
Embodiments of the present invention may be used to process links arranged with not only very fine pitch layouts but also coarser pitch arrangements, for example, greater than 2 μm, 3 μm pitch, and the like. The above-noted LIA Handbook (reference 5,
While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.
This application claims the benefit of U.S. provisional application Ser. No. 60/765,291, filed Feb. 3, 2006. This application is a continuation-in-part of U.S. Ser. No. 11/441,763, filed May 26, 2006. That application is a continuation application of U.S. Ser. No. 11/125,367, filed May 9, 2005, which, in turn, is a divisional application of the application which resulted in U.S. Pat. No. 6,972,268, which claims the benefit of U.S. provisional application Ser. No. 60/279,644, filed Mar. 29, 2001. This application is related to U.S. Ser. No. 11/130,232, filed May 17, 2005 which, in turn, is a continuation application of the application which resulted in U.S. Pat. No. 6,911,622 which, in turn, is a continuation which resulted in U.S. Pat. No. 6,559,412 which, in turn, is a continuation of the application which resulted in U.S. Pat. No. 6,300,590. The following U.S. patents are hereby incorporated by reference in their entirety: U.S. Pat. No. 6,911,622 (the '622 patent) entitled “Laser Processing”; U.S. Pat. No. 6,949,844 (the '844 patent) entitled “High-Speed Precision Positioning Apparatus”; U.S. Pat. No. 6,727,458 (the '458 patent) entitled “Energy-Efficient, Laser-Based Method And System For Processing Target Material”; U.S. Pat. No. 6,972,268 (the '268 patent) entitled “Methods And Systems For Processing A device, Methods And Systems For Modeling Same And The Device”; and U.S. Pat. No. 6,987,786 (the '786 patent) entitled “Controlling Laser Polarization.”
| Number | Date | Country | |
|---|---|---|---|
| 60765291 | Feb 2006 | US | |
| 60279644 | Mar 2001 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10108101 | Mar 2002 | US |
| Child | 11125367 | May 2005 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11125367 | May 2005 | US |
| Child | 11441763 | May 2006 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11441763 | May 2006 | US |
| Child | 11699297 | Jan 2007 | US |
