KR101173582B1 - Methods and systems for synchronized pulse shape tailoring - Google Patents

Abstract

The plurality of sub-resonators 12, 14 having different design configurations are coherents that fuse the pulse width characteristics given by the respective pulse energy profiles and / or the configurations of the sub-resonators 12, 14 with different laser actions. The common resonator section 18 is shared such that it can be substantially synchronized to provide a coherent laser pulse. The subresonators 12, 14 may share the laser medium 42 in a common section, or each separate subresonator section 28, 36 may have its own laser medium 42. Exemplary long and short sub-resonators 12, 14 are specially adapted with short rise times and long pulse widths at one or two wavelengths that can benefit a variety of laser and micromachining applications including memory link processing. Generated laser pulses.

Description

METHODS AND SYSTEMS FOR SYNCHRONIZED PULSE SHAPE TAILORING}

The present invention relates to controlling the laser pulse width and / or power profile, which can be improved by using a laser having two or more sub-resonators sharing a common section.

Diode-pumped (DP), solid-state (SS) lasers operating at high pulse repetition rates are widely used in a variety of applications, including laser micromachining. In these lasers, the pulse width is primarily determined by the resonator design and is affected by the laser pumping level and pulse repetition rate for a given laser medium. Once the resonator is configured, there are few practical ways to change the pulse width or temporal power profile for a given laser medium at a given pumping level and pulse repetition rate. However, in some applications, such as in processing links, especially stacks, better control of pulse width and time energy profile is desirable while maintaining other laser pulse parameters.

Lasers using fast diode master oscillator / fiber amplifier (MOPA) configurations can provide substantially square energy profile laser pulses with adjustable pulse widths of about 1 dB to 10 dB, but current fiber amplifiers Is a real difficulty in achieving a focused beam spot size that is small enough to provide any unpolarized laser power and typically achieve the desired micromachining behavior without adversely affecting nearby substrates or other materials. Has a disadvantageous wider wavelength spectral output. US patent applications 10 / 921,481 and 10 / 921,765 to Sun et al., Assigned to the assignee of the present patent application, describe how to obtain a MOPA pulse with an energy profile that is specifically adapted to a particular application.

Electro-optic (E-O) devices can also be used as optical gates to reshape the energy profile or pulse width of a laser pulse. However, operating the E-O device at high repetition rates, particularly above about 40 Hz, and synchronizing the laser pulses and action (s) of the E-O device to the desired accuracy are very difficult to achieve under practical constraints.

The laser pulses emitted by two independent lasers, each generating pulses having different temporal energy profile and pulse width, can be theoretically combined to provide an energy profile combined with the pulse width of the desired characteristic. In practice, however, the combination of such independently made pulses suffers from laser pulse jitter, which jitter causes any fluctuations in the laser pulse initiation to the laser pulse initiation control signal inherent in a typical Q-switched laser. (fluctuation). In many applications, pulse jitter is often greater than 5 Hz to 30 Hz, depending on the laser design and the laser pulse half speed. Such jitter is often too large to facilitate pulse coupling with the desired accuracy, especially when a set of combined pulses is desired to occur at intervals less than 200 microseconds. For example, a consistent and reproducible pulse energy profile in applications such as laser link processing may require timing stability between two pulses better than 1 ms. This synchronization problem becomes more important at high repetition rates, especially at repetition rates above about 40 Hz, for example.

It is an object of some embodiments to provide a method of controlling the energy profile and / or pulse width of a laser and / or laser pulse.

One embodiment of the present invention utilizes two or more sub-resonators that share a common resonator section such that the laser action is substantially self-synchronized. Each subresonator has a different design configuration, such as a subresonator length that is adapted to provide at least one different pulse energy profile and / or pulse width characteristic. When the shared portion of the resonator includes an output port, the resulting laser output provides a unique laser output pulse that fuses the energy profile and / or pulse width characteristics given by the configuration of the subresonator. In some embodiments, the sub-resonators share the laser medium in the common resonator section, and in some embodiments, each sub-resonator section may have its own laser medium. In one embodiment, the long and short sub-resonators share a common resonator section to produce laser pulses with short rise times and long pulse widths.

In some embodiments, the common resonator section includes a mirror with high reflectance, each subresonator section having its own output port. The laser profile characteristics from each subresonator can then be recombined outside the resonator, while many of the adverse effects of laser pulse jittering can be significantly reduced. The separate profile of the subresonator output undergoes a different selective harmonic conversion before the profiles are recombined into a laser output pulse that allows the laser output pulse to have a profile specially adapted using two or more laser wavelengths. Can be. In other embodiments, such different wavelength profiles may be controlled to occur at different times with respect to each other.

Further aspects and advantages will be apparent from the following detailed description of the preferred embodiment made with reference to the accompanying drawings.

1 is a schematic diagram of a laser consisting of two sub-resonators having a common resonator section comprising a laser medium and an output port.

FIG. 2A is a schematic diagram of a laser consisting of two sub-resonators, each comprising a laser medium sharing a common resonator section in which no laser medium is received;

2B is a schematic diagram of an alternative laser consisting of two sub-resonators comprising an AOM and a laser medium that each share a common resonator section in which no laser medium is received.

3A is a schematic diagram of a laser consisting of a laser medium sharing a common resonator section with mirrors having high reflectance and two sub-resonators including an output port;

3b is a schematic diagram of an alternative laser consisting of two sub-resonators comprising a laser medium, an AOM and an output port, each sharing a common resonator section with high reflecting mirrors;

4A-4C show power vs. time graphs of each short subresonator profile, long subresonator profile and consequently a specially adapted profile of output pulses.

5A-5C show power versus time graphs of each short subresonator profile, long subresonator profile, and consequently a specially adapted profile of output pulses when a first typical time delay is used.

6A-6C show power versus time graphs of each short subresonator profile, long subresonator profile, and consequently a specially adapted profile of output pulses when a second typical time delay is used.

7A-7C show power versus time graphs of each short subresonator profile, long subresonator profile, and consequently a specially adapted profile of output pulses when a third typical time delay is used.

1 is a schematic diagram of a laser 10 having a long subresonator 12 and a short subresonator 14 in which a beam splitter 16 is integrated to use a common resonator section 18. The beam splitter 16 may be partially reflective and transmissive mirrors to allow oscillation to occur simultaneously in both substantially long and short subresonators 14. Beam splitter 16 may alternatively be polarized to allow oscillation of substantially p-polarized laser beam in short sub-resonator 14 and substantially s-polarized laser beam in long sub-resonator 12. It may be a flag.

Referring to FIG. 1, the long negative resonator 12 is defined by the long negative resonator mirror 22 and the output port 24 located along the optical path 26. The long negative resonator 12 includes a common resonator section 18 and a long negative resonator section 28. The short sub-resonator 14 may be defined by the short sub-resonator mirror 34 and the output port 24 and thus comprise a common resonator section 18 and a short sub-resonator section 36. The laser 10 may also utilize an optional loss reduction subsection 38 with a loss reduction mirror 40. Preferably, the long subresonator mirror 22, the short subresonator mirror 34 and any loss reduction mirror 40 are to a desired wavelength made by the laser medium 42 located in the common resonator section 18. All are highly reflective (HR).

The laser medium 42 preferably utilizes conventional solid state lasers such as Nd: YAG, Nd: YLF, Nd: YVO ₄ or Yb: YAG, which make available all conventional laser wavelengths and their harmonics. Include. In some embodiments, the laser medium 42 is pumped directly or indirectly from the side by one or more diodes or diode arrays (not shown). However, those skilled in the art will appreciate that the pumping source may be located behind them if one or more of the long resonator mirrors 22, the short resonator mirrors 34 or the optional loss reduction mirrors 40 are suitably adapted to be an input coupler at the desired pumping wavelength. Get to know. Other known optical components (not shown) may additionally or alternatively be used to facilitate end pumping. One skilled in the art can also use one or more lamps, lasers or other pumping devices to provide the pumping light, and the laser medium 42 may be a different type of laser medium, such as a gas, CO ₂ , excimer or copper vapor laser medium. It can be seen that alternatively can be used.

The common resonator section 18 also includes a Q-switch 44, an acousto-optic modulator (AOM) or an electro-optic modulator (EOM), preferably located along the optical path 26. An aperture 48 may also be included in the common resonator section 18 and may preferably be located between the laser medium 42 or the Q-switch 44 and the output port 24. The output port 24 is preferably a partly reflective (PT) (about 5% to 20% transmissive) output coupling mirror to the desired wavelength produced by the laser medium 42.

Typical laser power repetition rates are greater than about 1 Hz, greater than about 1 Hz, greater than about 25 Hz, greater than about 40 Hz, greater than about 100 Hz and up to about 500 Hz or more. In a typical embodiment, other pulse parameters may include, but are not limited to, laser energy of 0.1 μJ to 10 μJ and even laser energy of up to 100 mJ at laser output repetition rates from about 1 Hz to about 500 Hz.

If desired, one or more wavelength converters 52 may be located along the optical path 26 outside of the common resonator section 18 to convert the laser output 50a into a harmonic laser output. Each wavelength converter 52 is preferably for potassium titanium oxide phosphate (KTiOPO ₄ ), beta-barium borate, beta-BaB ₂ O ₄ (BBO) and lithium triborate (LB ₃ O) for laser wavelength conversion. One or more non-linear crystals such as ₅ ). Typical fundamental laser wavelengths include, but are not limited to, 1064 nm, at 532 nm (twice frequency), 355 nm (three times frequency), 266 nm (four times frequency), and 213 nm (five times frequency). It has a harmonic wavelength. Those skilled in the art will appreciate that the wavelength converter 52 can be placed in the common resonator section 18 for internal cavity frequency conversion.

Since the short resonator 14 and the long resonator 12 share a common resonator section 18, the laser energy and the laser action in both subresonators 12, 14 are combined. This combination of laser action can resemble injection seeding from one subresonator to another, so that the laser action of two (or more) resonators is a single with substantially high profile stability. Self-synchronized with laser pulses.

FIG. 2A is a schematic diagram of a laser 80a having a long subresonator 82a and a short subresonator 84a integrated with the beam splitter 16 to use a common resonator section 88a. Common resonator section 88a is optically associated with long subresonator section 92a to form long subresonator 82a, and common resonator section 88a is short subresonator to form short subresonator 84a. Optically associated with section 94a. The laser 80a of FIG. 2A is very similar to the laser 10 of FIG. 1, so that many of their corresponding components are similarly named.

One significant difference in the laser 80 is that the long subresonator section 92a is provided to allow more diversity in the energy profile 160 (FIGS. 4-7) of the laser output 50b ₁ pulse. It contains the laser medium 42a, and the short subresonator section 94a contains the laser medium 42b. In most embodiments, the laser media 42a, 42b preferably comprise the same laser, but those skilled in the art will appreciate that the laser media 42a may be, for example, of construction, size, configuration or so long as their laser wavelengths are substantially similar. It will be appreciated that the dopant concentration may be different than the laser medium 42b. In one embodiment, the laser medium 42a has rods, disks, rectangular parallelepipeds, cubes, chips, slabs, or other shapes, and the laser medium 42b has these shapes. Have a different one.

In some preferred embodiments, the laser media 42a, 42b are pumped by the same pumping source and with the same pumping coupling method with the same pumping level and timing scheme through the use of conventionally known drive electronics. In some applications, such as link breaks, CW pumping is generally preferred. In other embodiments, the laser media 42a, 42b are pumped by different pumping sources and / or by different pumping coupling methods with different pumping levels and timing schemes through the use of conventionally known drive electronics. In some embodiments, for example, the laser medium 42a may be end pumped while the medium 42b is side pumped, and vice versa.

Although the common resonator section 88a may also include the laser medium 42, such embodiments are less preferred. Any polarizer 90 may be used in both the long resonator section 92a and the short subresonator section 94a, but is shown as being located within the long subresonator section 92a as an example.

2B is a schematic representation of an alternative laser 80b that is very similar to laser 80a, with the majority of their corresponding components being similarly named. One major difference with the laser 80a is that the common Q-switch 44 is removed from the common resonator section 88b and the two independent Q-switches 44a and 44b (such as AOM) are long. That is inserted into the subresonator section and the short subresonator sections 92b and 94b, respectively. Q-switches 44a and 44b may be initiated at the same time by the same driver (such as an RF driver not shown) or by separate but synchronized independent drivers.

Alternatively, Q-switches 44a and 44b may be initiated at different times by separate independent drivers to further enhance the retrofit capability of profile 160 of the pulse of laser output 50b ₂ . In order to ensure laser energy coupling between the two subresonators 82b and 84b, one skilled in the art will ensure that the Q-switches described later are initiated before the laser action is stopped in the sub-resonators that accommodate the remaining Q-switches. It will be appreciated that the delay time between the commencement of 44a and 44b should be limited. Although polarizer 90 is not shown in FIG. 2B, polarizers may be used in one or more subresonator sections 92b, 94b and / or common resonator section 88b.

3A is a schematic diagram of a laser 110a having a long subresonator 112a and a short subresonator 114a integrated with the beam splitter 16 to utilize a common resonator section 118a. Common resonator section 118a is optically associated with long subresonator section 122a to form long subresonator 112a, and common resonator section 118a is short subresonator section to form short subresonator 114a. Optically associated with 124a. The laser 110a of FIG. 3A is very similar to the laser 80a of FIG. 2A, so that many of their corresponding components are similarly named. The big difference between these lasers is that in the laser 110a, the output port 24 is replaced by a highly reflective mirror 116, and the long and short subresonator mirrors 22, 34 are short and long output ports 24c, 24d. Substituted with, it provides separate but time-synchronized profiles 150, 152 (FIGS. 4-7) of the laser power 50c ₁ , 50d ₁ , respectively. One or more additional or alternative openings 48 may be included in the subresonator sections 122a and 124a between the laser media 42c and 42d and the respective output ports 24c and 24d.

Those skilled in the art will regard these profiles 150, 152 as forming single time pulses with specially modified energy profile characteristics, regardless of whether the profiles 150, 152 of the laser outputs 50c ₁ , 50d ₁ are recombined. It can be seen that the profiles 150, 152 are merged in time by a common resonator section with high timing accuracy. The laser outputs 50c ₁ , 50d ₁ are directed and recombined through conventional optics such as mirror 130 and combiner 132 to provide a synchronized laser output 50e ₁ with specially adapted pulses. Can be. Alternatively, laser power 50c ₁ , 50d ₁ can be used to independently provide different energy profile portions or target positions that collide with separate targets to specially adapted synchronized pulses.

The laser outputs 50c and 50d may also pass through any of the wavelength converters 52c and 52d, respectively, thereby splitting the same or different wavelength conversions. In one example, laser output 50c is converted to the second harmonic wavelength and laser output 50d is converted to the fourth harmonic wavelength. Such laser outputs 50c ₁ , 50d ₁ may be recombined to provide a specially adapted pulse of laser output 50e ₁ such that each pulse contains two or more selected wavelengths.

3B is a schematic diagram of an alternative laser 110b that is very similar to the laser 110a shown in FIG. 3A, with the majority of the corresponding components being similarly named. One big difference in laser 110b is that common Q-switch 44 is removed from common resonator section 118b, and two independent Q-switches 44a and 44b have a long sub resonator section and a short portion. Is inserted into the resonator sections 122b and 124b, respectively. Q-switches 44a and 44b may be initiated at the same time by a single driver (such as an RF driver not shown) or by separate but synchronized independent drivers.

The Q-switches 44a and 44b can be initiated at different times by separate independent drivers, further improving the retrofit capability of the profile 160 of the pulses of the laser output 50e ₂ . In some embodiments, the delay time between the initiation of the Q-switches 44a and 44b (or vice versa) further improves the laser energy coupling between the two sub-resonators 112b and 114b, which is later disclosed by the Q-switch. To do so, it can be limited so that the laser action in the sub-resonator accommodating the remaining Q-switch can be started before it is stopped.

Pulses of laser power 50a, 50b ₁ , 50b ₂ , 50c ₁ , 50c ₂ , 50d ₁ , 50d ₂ , 50e ₁ , 50e ₂ as provided by any of the exemplary embodiments {generally laser power ( 50) is also preferably directed towards each target that can be moved by the target positioning system by the beam delivery system. The beam delivery system may include any of a variety of conventional optical components, such as a beam expander, a mirror, and a focusing lens to create a focused spot size. For link processing, the diameter of the focused laser spot is usually in the range between about 0.5 μm and about 3 μm, preferably with link width, link pitch size, link material and other link structures and treatments. 40% to 100% greater than the width of the link, depending on considerations. In other laser applications, the laser spot size can be adjusted from tens of microns to hundreds of microns to suit the application requirements.

Preferred beam delivery and positioning systems are described in detail in US Pat. No. 4,532,402 entitled "Method and Apparatus for Positioning a Focused Beam on an integrated Circuit" by Overbeck. Such positioning systems may alternatively or additionally include the improvements described in US Pat. No. 5,751,585 to Cutler et al., US Pat. No. 6,430,465B2 to Cutler et al. US Pat. Beam positioners can be used, which are assigned to the assignee of the present patent application. Other fixed-head systems, galvanometers, piezoelectric or voice coil control mirrors or linear motor driven conventional positioning systems or 5300 manufactured by Electro Scientific Industries, Inc., Portland, Oregon Fast positioner-head systems such as those used in the 9300 or 9000 model series can also be used.

Since the overall duration of each laser pulse is shorter than 1000 ms (typically 300 ms to 500 ms), conventional link processing positioning systems require less than about 0.1 μm (shorter than the link width) laser spot position within such 1000 ms duration. Can be moved. Thus, the laser system can handle on-the-fly links, i.e., the positioning system does not need to interrupt movement when the laser system emits a laser pulse. In some embodiments, regardless of when the spike or peak is located, the laser spot of the long and short subresonator profile includes the link width.

1 to 3, the long negative resonators 12, 82a, 82b, 112a, 112b (generally the long negative resonator 12) and the short negative resonators 14, 84a, 84b, 114a, 114b { The characteristics of the generally short resonator 14 are different and are independently selected to give the laser output 50 the desired properties. In one embodiment, the lengths of the long resonator 12 and the short resonator 14 are selected to impart specific pulse profile characteristics to the laser output 50. In particular, the length of the short subresonator sections 36, 94a, 94b, 124a, 124b (collectively, the short resonator section 36) divides the short duration during the rising edge by the pulse of the laser output 50. In order to adjust the length of each common resonator section 18, 88a, 88b, 118a, 118b (collectively the common resonator section 18) and the long subresonator sections 28, 92a, 92b, 122a. , 122b) (generally long resonator section 28) is adjusted to cooperate with the length of each common resonator section 18 to impart a long pulse width to the pulse of laser output 50. Specific values of these pulse characteristics can be independently selected, and then the length or other characteristics of the short subresonator section 36, the long subresonator section 28 and the common resonator section 18 are desired for the laser output 50. It may be selected in cooperation with other laser parameters to achieve a pulse profile.

The relationship between the resonator characteristics and the pulse profile is relatively complex. However, for a given laser gain factor with a given pumping energy, the pulse width generally depends on the number of "round trips" that photons make between the resonator end mirrors during the laser period. Therefore, for a particular laser operated under a similar parameter with a given laser medium 42, a given pumping level and a given pulse repetition rate, the pulse width is generally directly proportional to the cavity length. Therefore, in general, the shorter the cavity, the shorter the pulse width, and the longer the cavity, the longer the pulse width. In the link processing example, a typical Nd: YAG laser with an 8-10 cm long resonator pumped by a 3W diode has a pulse width of 20 kHz to about 10 kHz. Thus, by keeping the remaining parameters generally the same and selectively shortening the resonator, a pulse width of 5 [mu] s can be obtained, or optionally by making the resonator longer, a pulse width of 20 [mu] s can be obtained. The rise time is also affected by the pulse width. The rise time will generally be close to the maximum width at about half of the maximum peak power (time between points of the pulse profile at half of its maximum power). Thus, shorter pulse widths result when a shorter rise time is defined.

Therefore, the components of each subresonator can be adapted by the skilled worker, for example, to facilitate the generation of its independent pulse propagation properties according to known techniques. For example, the placement and curvature of the highly reflective mirrors, the surface curvature and length of the laser medium 42, and the pumping and doping levels can all be adjusted to sufficiently similar constant propagation characteristics from the two combined sub-resonators so that they are manufactured It is aligned on the surface of the product in the process and produces a substantially similar spot size. Alternatively, the components of each subresonator may be adapted such that certain propagation characteristics, such as spot size, are intentionally different. The transmittance of the output coupler can also be adjusted to affect the pulse duration. As the transmittance increases, the pulse width decreases, and as the transmittance decreases, the pulse width increases.

Link processing with specially modified pulse shapes derived from the lasers described herein provides better processing of broken links than performing conventional link processing without sacrificing a wider processing window and throughput. Provide quality. The versatility of the laser output pulses allows for better modification of particular link characteristics or other laser processing operations.

4A-4C (collectively, FIG. 4) illustrate the time graph versus power and typically a specially adapted profile 160a of each hypothetical short resonator profile 150 and long subresonator profile 152. Illustrated. The short sub-resonator profile 150 and the long sub-resonator profile 152 are virtual in that they can represent what each sub-resonator provides, unless they are combined, but such a short sub-resonator profile ( 150 and elongated sub-resonator profile 152 are not actually present separately in many typical embodiments such as those shown in FIGS. 1, 2A and 2B.

Referring to FIG. 4A for some embodiments, the short subresonator section 36 has a short pulse width of typically 2 ms to 15 ms and a shorter resonator profile 150 of less than about 8 ms, preferably about It is adapted to provide rise times less than 5 ms. Those skilled in the art will appreciate that various subranges or alternative ranges regarding the pulse width and rise time of such a short subresonator profile 150 are possible. Typical alternative ranges include pulse widths less than 10 ms and rise times less than 2 ms.

Referring to FIG. 4B for some embodiments, the long subresonator section 28 is a long pulse width having a typical pulse width of greater than 10 ms, preferably 15 ms to 50 ms in the long sub resonator profile 152. , It is adapted to provide rise times longer than 5 ms and rise times, typically greater than 8 ms or 10 ms. Those skilled in the art will appreciate that various alternative ranges for the pulse width and rise time of such long resonator profiles 152 are possible. Some typical alternative ranges include pulse widths from 15 ms to 30 ms or pulse widths greater than 20 ms.

Referring to FIG. 4C, power profile 160 is a specially adapted energy including spike, rise time and pulse width characteristics derived from hypothetical short subresonator profile 150 and hypothetical long subresonator profile 152. Show the profile. Each power profile 160a represents a power profile of a single time pulse of the laser output 50 which may generally be the sum of the hypothetical profiles 150, 152. However, those skilled in the art will appreciate that the virtual profiles 150, 152 may not be entirely additive, and that the remaining derivatives of the virtual profiles 150, 152 may produce the power profile 160. The power profile 160a may be characterized by having a short rise time and a long pulse width. Alternatively, power profile 160a may be characterized as having two attached spikes with separate peaks. Peaks can preferably be separated within a time period from about 15 ms to about 300 ms, so that the duration of each pulse can be greater than 300 ms.

The short rise time (and somewhat higher peak power) provided by the short resonator section 36 facilitates, for example, the removal of most of the passivation or other layers overlying the semiconductor memory link, even some implementations. In the example, link removal is similarly started. The longer pulse widths and lower peak power resulting from the long resonator 12 help to remove the link completely without compromising the integrity of the underlying or neighboring substrates.

5A-5C (collectively, FIG. 5) show that when a typical time delay Td ₁ is used, a long negative resonator profile 152 and typically a specially modified profile 160b and each virtual short negative resonator The time graph versus power of the profile 150 is shown.

2B, 3B, and 5, embodiments such as those illustrated by lasers 80b, 110b having Q-switches 44a, 44b in separate subresonator sections may be described as short subresonators and long subresonators. It is tailored to introduce a time delay (typically Td) between the onset of the laser action and vice versa. In the exemplary embodiment shown in FIG. 5, the Q-switch 44a in the long subresonator 82 is opened with a short delay time Td ₁ , ie, the short resonator 84 in which the Q-switch 44b is short. Immediately after opening, produces a specially adapted profile 160b. Each power profile 160b represents the power profile of a single time pulse of laser output 50. As discussed above, the virtual profiles 150 and 152 may or may not be additionally overall and other derivatives thereof may produce variations of the power profile 160b.

Similarly, FIGS. 6A-6C (collectively, FIG. 6) typically show each virtual short resonator profile 150 and long subresonator profile 152 and typical when a long time delay Td ₂ is used. Shows the power graph versus the power graph of the profile 160c, which has been specially adapted. In the exemplary embodiment shown in FIG. 6, the Q-switch 44a in the long subresonator 82 opens after a long delay time Td ₂ which ends immediately before the laser action is stopped in the short subresonator 84. Create a modified profile 160c. Each power profile 160c represents the power profile of a single time pulse of laser output 50. As mentioned above, the virtual profiles 150 and 152 may or may not be additive overall, or other derivatives from them may produce variations of the power profile 160c.

7A-7C (collectively, FIG. 7) typically show the respective short subresonator profile 150 and the long subresonator profile 152 and specially adapted profiles when a long time delay Td ₃ is used. 160d) time graph versus each power. In the exemplary embodiment shown in FIG. 7, the AOM 44b in the short sub-resonator 84 has a median delay Td _{3 that} is substantially in the middle of the spike of the profile 150 with respect to the spike of the profile 152. Is opened after AOM 44a to produce a specially modified profile 160b. Each power profile 160d represents the power profile of a single time pulse of laser output 50. As mentioned above, the imaginary profiles 150 and 152 may or may not be additive overall, or other derivatives thereof may produce variations of the power profile 160d.

With respect to the lasers 10, 80a. 80b, the laser profile 160 of the pulses emitted at each output port is generally inseparable into their virtual profiles 150, 152 from the combined subresonators (polarizing element Unless used). However, those skilled in the art will appreciate that the short subresonator profile 150 and the long subresonator profile 152 appear from separate output ports from the lasers 110a, 110b and continue to have high profile stability and pulse-to-pulse. It is recombined to provide a single pulse of laser output 50 with profile 160 with consistency.

Alternative embodiments of the lasers 110a and 110b allow for various unique and useful possibilities regarding the profile 160. In one embodiment, the short sub-resonator profile 150 is harmonic converted to ultraviolet wavelength (UV), and the long sub-resonator profile 152 has a short rise time in UV and a long pulse width in the green wavelength range. Harmonic is converted to the green wavelength to provide. In another embodiment, the short sub-resonator profile 150 is harmonic transformed to a wavelength of 355 nm, and the long resonator profile 152 remains at the fundamental wavelength of 1064 nm, resulting in short rise times at 355 nm and long at 1064 nm. Provide a profile 160 having a pulse width. In another embodiment, a fundamental wavelength of 1.32 μm is used to produce a long resonator profile 152 and a short resonator profile 150 of twice harmonic (660 nm) or tripled (440 nm), It provides a laser output pulse with a short rise time at a purple or blue wavelength and a long pulse width at a wavelength of 1.32 μm. Initial small spot size UV short pararesonator profile 150 removes or ruptures the passivation layer on top, minimizing crater size and reducing cracking expansion or formation, while the portion of the link. Can be used to remove it. The long sub-resonator profile 152, which is then a large spot size visible or IR, reduces the risk of damage to silicon or other substrates, especially below conventional visible or IR output pulse energy or peak power. Remove

Alternatively, spikes in the short resonator profile 150 may be delayed to occur somewhere along the pulse width of the long subresonator profile 152. Such delayed spikes may be useful, for example, with respect to machining through the embedded passivation layer. Visible or IR spikes may alternatively be introduced to occur somewhere along the pulse width of the long subresonator profile 152 of UV, as required for other applications.

The ability to modify the pulses specifically for different profile portions at different wavelengths adds extra versatility. For link blowing and other applications, mixing conventional IR laser wavelengths and their harmonics presents a smaller laser beam spot size for processing some layers of the target and less problems with other layers of the target. Allows the use of wavelengths that become Because the profile and duration of the laser output 50 can be modified and reduce the risk of damage to underlying or neighboring passivation structures, new materials or sizes can be used.

Since wavelengths much shorter than about 1.06 μm can be used to produce critical spot size diameters less than about 1.5 μm, the pitch between the centers between the links treated with laser output 50 is a conventional single IR laser. It may be substantially smaller than the pitch between links broken by the beam break pulse. Therefore, processing of narrower and more dense links can be facilitated, resulting in a better link removal solution and allowing such links to be placed closer together, increasing circuit density.

Similarly, the versatility of better adaptation of laser pulse power profile 160 provides better flexibility in accommodating different or more complex passivation characteristics. For example, the passivation layer above or below the link can be made of materials other than conventional materials or can be modified to have a height other than the usual height if desired.

The underlying passivation layer can include any conventional passivation material, such as silicon dioxide (SiO ₂ ), silicon oxynitride (SiON), and silicon nitride (Si ₃ N ₄ ). The underlying passivation layer may comprise the same passivation material or different passivation material (s) as the passivation layer above. The underlying passivation layer, in particular in the target structure, includes low K materials, low K dielectric materials, low K oxide based dielectric materials, orthosilicate glass (OSG), fluorosilicate glass, organo Silicate glass, tetraethylorthosilicate-based oxide (TEOS-based oxide), methyltriethoxyorthosilicate (MTEOS), propylene glycol monomethyl ether acetate (PGMEA), silicate esters , Hydrogen silsesquioxane (HSQ), methyl silsesquioxane (MSQ), polyarylene ethers, benzocyhclobutene (BCB), SiCOH or SiCOH-derived membranes ( films (such as "Black Diamond" sold by Applied Materials) or spin on-based low K dielectric polymers (Dow Chemical Company) One that is comprises a material formed from the same) and "SiLK" can be formed from a brittle material that is not limited to these. Underlying passivation layers made from some of these materials are more prone to rupture when their targeted links are broken or removed by conventionally shaped laser pulse link-removal operations. Those skilled in the art will appreciate SiO ₂ , SiON, Si ₃ N ₄ , low K materials, low K dielectric materials, low K oxide based dielectric materials, OSGs, fluorosilicate glasses, organosilicate glasses, HSK, MSQ, BCB , SiLK ^TM and Black Diamond ^TM are the actual layer materials and TEOS, MTEOS and polyarylene ethers are the semiconductor condensate precursors. Although some of the newer overlying passivation layers are less receptive to conventional laser processing and / or the underlying passivation layer may be less sensitive to conventional laser processing, the techniques described herein are different. It often shows greater flexibility in handling layers with properties.

It will be apparent to those skilled in the art that many changes can be made in the details of the above-described embodiments without departing from the underlying principles of the invention. Therefore, the scope of the present invention should be determined only by the following claims.

As mentioned above, the present invention can be used to control the laser pulse width and / or power profile.

Claims (95)

A method of controlling the temporal energy profile of a laser output pulse, Using a first sub-resonator having a first sub-resonator length that gives rise time characteristics to the first sub-resonator pulse profile in response to laser pulse initiation, where the first sub-resonator is responsible for the first sub-resonator length Using a first subresonator section having a first subresonator section having a first subresonator section length, Using a second sub-resonator having a second sub-resonator length for imparting a pulse width characteristic to the second sub-resonator pulse profile in response to the laser pulse initiation, the second sub-resonator being the source of the second sub-resonator length. Using a second subresonator section having a second subresonator section having a second subresonator section length, the second subresonator length being longer than the first subresonator length, Using a common resonator subsection shared by the first and second subresonators to cause a given characteristic to be expressed from the first and second subresonator pulse profiles during the laser pulse, the common resonator subsection being the first Using a common resonator subsection, having a length that contributes to both the subresonator length and the second subresonator length, Initiating a laser pulse to express a given characteristic from the first and second subresonator pulse profiles, and Emitting a laser output pulse having a given rise time characteristic from the first sub-resonator and a given pulse width characteristic from the second sub-resonator; And controlling the time energy profile characteristic of the laser output pulse. 2. The first sub-resonator has a short first sub-resonator length that imparts a short rise time to the laser output pulses so that the laser output pulses exhibit a short rise time and a long pulse width. A method for controlling the time energy profile characteristic of a laser output pulse having a long second subresonator length that imparts a long pulse width to the laser output pulse. delete 2. The method of claim 1, wherein the laser output pulses exhibit two separate peaks within a time period of 15 microseconds to 300 microseconds. delete delete The method of claim 1, wherein the common resonator subsection comprises a Q-switch. The method of claim 1, wherein each of the first and second subresonator sections comprise a Q-switch. The method of claim 1, wherein the common resonator subsection comprises a solid state laser medium. delete The method of claim 1, wherein the laser output pulses are converted to different wavelengths by the use of redundant cavity wavelength converters. The method of claim 1, wherein the common resonator subsection comprises one or more wavelength converters. The method of claim 1, wherein initiation of the first and second subresonator pulse profiles is simultaneous. delete delete The method of claim 1, wherein a time delay is introduced between the start of the first subresonator pulse profile and the second subresonator pulse profile. delete delete The method of claim 1, wherein the first and second subresonator sections each comprise a solid state laser medium. delete delete delete 20. The method of claim 19, wherein the solid state laser media of the first and second subresonator sections have different dimensions. delete 20. The method of claim 19, wherein the first and second subresonator sections each comprise one or more wavelength converters. 20. The method of claim 19, wherein the solid state laser media of the first and second subresonator sections are pumped to different levels. delete 20. The method of claim 19, wherein pumping is initiated with respect to the solid state laser medium of the first and second subresonator sections at different times. 20. The method of claim 19, wherein pumping is initiated with respect to the solid state laser medium of the first and second subresonator sections at the same time. delete delete The method of claim 1, wherein the common resonator subsection comprises a common output port from which laser output pulses are emitted. 33. The method of claim 32, wherein the laser output pulse has a time energy profile that is inseparable into the pulse profiles of the first and second subresonators. delete delete delete delete delete delete delete delete delete delete delete delete delete A method of generating a laser output pulse having a laser output pulse profile comprising at least two wavelengths, the method comprising: Using a common resonator subsection having a common resonator subsection length along a common optical path, Using a beam splitter positioned to intersect the common optical path, Using a first sub-resonator section having a first sub-resonator section and having a first sub-resonator section length intersecting with the common optical path in the vicinity of the beam splitter, wherein the first sub-resonator section and the common resonator subsection are: Forming a first sub-resonator having a first sub-resonator length including a sub-resonator section length and a common resonator sub-section length, the first sub-resonator length imparting a first spike characteristic and a first pulse width characteristic to each laser pulse; Using, the first sub-resonator section, Using a second sub-resonator section having a second sub-resonator section having a second sub-resonator section length intersecting with the common optical path in the vicinity of the beam splitter, wherein the second sub-resonator section and the common resonator subsection Forming a second sub-resonator having a second sub-resonator length including a sub-resonator section length and a common resonator sub-section length, the second sub-resonator length imparting a second spike characteristic and a second pulse width characteristic to each laser pulse; Wherein the second subresonator length is longer than the first subresonator length, using the second subresonator section, Using first and second solid state laser media located in each of the first and second subresonator sections to receive laser pumping light from one or more laser pumping sources, the first and second laser media at a fundamental wavelength. Adapted to facilitate laser action, a common resonator section connects the laser action in the first sub-resonator and the laser action in the second sub-resonator to impart from the first sub-resonator the first spike characteristics and the second sub-resonator Using the first and second solid state laser media, causing a propagation of a laser pulse exhibiting at least a second pulse width characteristic, wherein Each laser pulse propagates through a first output port and exhibits a first spike and pulse width characteristic, and a second laser propagates through a second output port and exhibits a second spike and second pulse width characteristic. Using a first output port from the first sub-resonator section and a second output port from the second sub-resonator section to divide into outputs, Using a first wavelength converter located along the first beam path from the first output port to convert the first laser output to the first wavelength or to convert the second laser output to the second wavelength; Using a second wavelength converter located along a second beam path from the port; and The first laser output to provide a laser output pulse having at least a first spike characteristic at the base or first wavelength and at least a second pulse width characteristic at the base or second wavelength such that the laser output pulse exhibits at least two separate wavelengths. And combining the second laser output And a laser output pulse having a laser output pulse profile comprising at least two wavelengths. A method of controlling the time energy profile or pulse width characteristics of a laser output pulse, Using a first subresonator with a first design feature to impart a first energy profile or pulse width characteristic to each laser pulse, Using a second subresonator having a second design feature for imparting a second energy profile or pulse width characteristic to each laser pulse, wherein the first and second design features impart different characteristics to the pulse of the laser output, Using the second secondary resonator, Using a common resonator subsection shared by the first and second sub-resonators to combine the laser action in the first and second sub-resonators; and Directing a laser output pulse having a laser output energy profile or pulse width characteristic derived from the first and second energy profile or pulse width characteristics to a target; And controlling the time energy profile or pulse width characteristic of the laser output pulse. delete delete delete delete delete delete delete delete As a solid state laser, A common resonator subsection having a common resonator subsection length along a common optical path, A solid state laser medium adapted to facilitate the generation of laser pulses and located along a common optical path for receiving laser pumping light from a laser pumping source, A Q-switch located along a common optical path to initiate each laser pulse propagation resulting in the generation of each laser pulse, Beam splitter positioned to intersect the common optical path, A first sub-resonator section having a first sub-resonator section length, the first sub-resonator section having a first sub-resonator section located along a first sub-resonator path that intersects with the common optical path in the vicinity of the beam splitter; The common resonator subsection forms a first sub-resonator having a first sub-resonator length including a first sub-resonator section length and a first resonator length including the common resonator sub-section length, the first sub-resonator length starting each laser pulse at each laser pulse. A first subresonator section, which gives rise time characteristics from the event, A second sub-resonator section having a second end resonator path located along a second sub-resonator path that intersects with the common optical path in the vicinity of the beam splitter and having a second sub-resonator section length, the second sub-resonator section and the common resonator section; The section forms a second sub-resonator having a second sub-resonator length including a second sub-resonator section length and a second sub-resonator length comprising a common resonator sub-section length, the second sub-resonator length being determined from each laser pulse initiation event at each laser pulse. A second subresonator section, imparting a pulse width characteristic, wherein the second subresonator length is longer than the first subresonator length; From each pulse start event, an output port located along a common optical path for propagating a laser pulse having a rise time characteristic derived from the first sub-resonator and a pulse width characteristic derived from the second sub-resonator Including, solid state laser. delete delete delete delete delete delete delete delete delete delete delete delete delete delete As a solid state laser, First and second solid state laser media adapted to facilitate laser action, for receiving laser pumping light from one or more laser pumping sources, A common resonator subsection having a common resonator subsection length along a common optical path, Beam splitter positioned to intersect the common optical path, A first subresonator section having a first laser resonator path located along a first subresonator path intersecting a common optical path in the vicinity of the beam splitter and having a first subresonator section length, the first subresonator section and the common resonator section. The section forms a first sub-resonator having a first sub-resonator length comprising a first sub-resonator section length and a first resonator sub-section length, the first sub-resonator length imparting spike characteristics to each laser pulse. Subresonator section and A second subresonator section having a second laser resonator path located along a second subresonator path intersecting the common optical path in the vicinity of the beam splitter and having a second subresonator section length, the second subresonator section and the common resonator part; The section forms a second sub-resonator having a second sub-resonator length including a second sub-resonator section length and a second resonator length including a common resonator sub-section length, the second sub-resonator length imparting a pulse width characteristic to each laser pulse. The second subresonator length comprises a second subresonator section, longer than the first subresonator length, The common resonator section links the laser action of the first sub-resonator with the laser action of the second sub-resonator to cause the propagation of a laser pulse having a given spike characteristic from the first sub-resonator and a given pulse width characteristic from the second sub-resonator. , Solid state laser. delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete

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