A method of dividing a wafer having a plurality of devices, which are formed in a plurality of areas sectioned by streets formed in a lattice pattern on the front surface, and having test metal patterns which are formed on the streets, comprising the steps of: a laser beam application step for carrying out laser processing to form a dividing start point along a street on both sides of the test metal patterns by applying a laser beam along the street on both sides of the test metal patterns in the street formed on the wafer; and a dividing step for dividing the wafer which has been laser processed to form dividing start points along the dividing start points by exerting external force to the wafer, resulting in leaving the streets having the test metal patterns formed thereon behind.

Wafer dividing method

This invention is a catheter-based device for generating an ultrasound excitation in biological tissue. Pulsed laser light is guided through an optical fiber (10) to provide the energy for producing the acoustic vibrations. The optical energy is deposited in a water-based absorbing fluid, e.g. saline, thrombolytic agent, blood or thrombus, and generates an acoustic impulse in the fluid through thermoelastic and/or thermodynamic mechanisms. By pulsing the laser at a repetition rate (which may vary from 10 Hz to 100 kHz) an ultrasonic radiation field can be established locally in the medium. This method of producing ultrasonic vibrations can be used in vivo for the treatment of stroke-related conditions in humans, particularly for dissolving thrombus or treating vaspasm. The catheter (14) can also incorporate thrombolytic drug treatments as an adjunct therapy and it can be operated in conjunction with ultrasonic detection equipment for imaging and feedback control and with optical sensors for characterization of thrombus type and consistency.

Opto-acoustic thrombolysis

An EUV light source is disclosed that may include a laser source, eg CO2 laser, a plasma chamber, and a beam delivery system for passing a laser beam from the laser source into the plasma chamber Embodiments are disclosed which may include one or more of the following; a bypass line may be provided to establish fluid communication between the plasma chamber and the auxiliary chamber, a focusing optic, eg mirror, for focusing the laser beam to a focal spot in the plasma chamber, a steering optic for steering the laser beam focal spot in the plasma chamber, and an optical arrangement for adjusting focal power

Laser produced plasma euv light source

Systems and methods are disclosed for reducing the influence of plasma generated debris on internal components of an EUV light source. In one aspect, an EUV metrology monitor is provided which may have a heater to heat an internal multi-layer filtering mirror to a temperature sufficient to remove deposited debris from the mirror. In another aspect, a device is disclosed for removing plasma generated debris from an EUV light source collector mirror having a different debris deposition rate at different zones on the collector mirror. In a particular aspect, an EUV collector mirror system may comprise a source of hydrogen to combine with Li debris to create LiH on a collector surface; and a sputtering system to sputter LiH from the collector surface. In another aspect, an apparatus for etching debris from a surface of a EUV light source collector mirror with a controlled plasma etch rate is disclosed.

Systems and methods for reducing the influence of plasma-generated debris on the internal components of an EUV light source

An injection seeded modular gas discharge laser system (2) capable of producing high quality pulsed beams at pulse rates of about 4,000 Hz or greater and at pulse energies of about 5 mJ or greater. Two separate discharge chambers are provided, one of which is a part of a master oscillator (10) producing a very narrow band seed beam, which is amplified (12) in the second discharge chamber. The chambers can be controlled separately permitting separate optimization of wavelength parameters in the master oscillator and optimization of pulse energy parameters in the amplifying chamber. A preferred embodiment in the ArF excimer laser system configured as a MOPA and specifically designed for use as a light source for integrated circuit lithography. In the preferred MOPA embodiment, each chamber comprises a single tangential fan (10A) providing sufficient gas flow to permit operation at pulse rates of 4,000 Hz or greater by cleaning debris from the discharge region in less time that the approximately 0.25 milliseconds between pulses. The masters oscillation is equipped with a line narrowing package having a very fast tuning mirror capable of controlling centerline wavelength on a pulse-to-pulse basis at repetition rates of 4000 Hz or greater to a precision of less than 0.2 pm.

Very narrow band, two chamber, high rep rate gas discharge laser system

A fiber optic device for remote delivery of intense ultraviolet optical signals comprising an excimer laser source and an optical fiber. The output of the pulsed, transverse discharge, high pressure laser source is coupled to an articulating reflection mechanism which directs the pulsed laser output to an input end of the optical fiber. The optical fiber serves to transmit the light from the laser source to a remote location or target. The excimer laser further comprises a segmented first elongated laser electrode and a coextensive second laser electrode which is substantially solid. The discharge is stabilized by inductors connected to each segment of the first electrode and further by preionization electrodes located adjacent and coextensive with the second electrode. The preionization electrodes comprise a central conductor surrounded by a dielectric sleeve. The laser further comprises a closed gas system for the lasing medium gas. The gas system comprises a circulating blower, a heat exchanger and a cryogenic trap. The optical fiber comprises a central core having a substantially constant index of refraction and a cladding having an index of refraction which varies as the radius of the cladding. Thus, the invention advantageously permits high intensity ultraviolet light to be generated over extended periods of time utilizing a sealed laser and furthermore delivers the high intensity ultraviolet light to a remote location through an optical fiber with minimal damage to the fiber. The system is particularly well suited for application as a percutaneously introduced laser angioplasty system for removal of vascular obstructions.

Laser catheter system

An electrical excitation circuit (10) for a gas laser. The electrical excitation circuit includes a charging circuit (16), connected in series with a pulse forming network (18) between a power source (12) and the laser load (14). The charging circuit (10) includes a capacitor charged by the power source (12) and a thyratron (S1) for transferring voltage to the pulse forming network (18). Alternatively, the charging circuit (10) includes a capacitor charged upon the firing of a silicon controlled rectifier (SCR1) through a saturable step-up transformer (XFMR1) which saturates for transferring voltage to the pulse forming network (18). The pulse forming network (18) includes a saturable inductor switch (S2) positioned with respect to a capacitor so that, when the voltage on the capacitor reaches a predetermined level, saturation on the saturable inductor switch (S2) releases electrical energy stored in the capacitor to the laser load (14). The saturable inductor switch (S2) is biaised by means of an electrical bias current which can be adjusted so that the saturable inductor switch (S2) saturates after the capacitor is fully charged, thereby controlling the time of application of the high voltage pulse to the laser load (14). The pulse forming network (18) preferably includes an additional capacitor and a magnetic diode charging inductor (L3) which is also biased by means of an electrical bias current. The capacitor is charged through the magnetic diode charging inductor (L3) and discharges in series with the other capacitor when the saturable inductor switch (S2) saturates, thereby doubling the voltage across the laser load (14) at the time of discharge. The magnetic diode charging inductor (L3) also minimizes prepulse across the laser load (14) during charging of the additional capacitor. Neither the saturable inductor switch (S2) nor the magnetic diode charging inductor (L3) are in the discharge loop (LD) with the laser load (14) thereby minimizing the inductance of the discharge loop (LD).

Theodore S. Fahlen

Papers

Laser catheter system

Electrical excitation circuit for gas lasers

Magnetically switched 150-W XeCl laser

Corona preionized 300-W excimer laser

All solid-state power conditioning for a 150-W XeCl laser