Patent Application
20230219171
The present disclosure relates to a glass processing method.
In recent years, a semiconductor exposure apparatus is required to improve the resolution thereof as semiconductor integrated circuits are increasingly miniaturized and highly integrated. To this end, reduction in the wavelength of light outputted from a light source for exposure is underway. For example, a KrF excimer laser apparatus, which outputs a laser beam having a wavelength of about 248 nm, and an ArF excimer laser apparatus, which outputs a laser beam having a wavelength of about 193 nm, are used as a gas laser apparatus for exposure.
As a method for processing glass to form a microscopic hole, there is, for example, a method for creating an altered portion with a femtosecond or ultraviolet laser and utilizing the fact that the etching rate in the altered section is greater than that in the other portion, and a method for directly processing glass with an excimer laser apparatus.
A glass processing method according to a viewpoint of the present disclosure includes generating a pulse laser beam by using a laser oscillator, and irradiating alkali-free glass to be processed with the pulse laser beam. A wavelength of the pulse laser beam ranges from 248 nm to 266 nm, and the pulse laser beam has an energy ratio greater than or equal to 91% but smaller than or equal to 99% in a region from 5 ns after a pulse rises to 400 ns.
A glass processing method according to another viewpoint of the present disclosure includes generating a first pulse laser beam having a wavelength ranging from 248 nm to 266 nm by using a laser oscillator, generating a second pulse laser beam having an energy ratio greater than or equal to 91% but smaller than or equal to 99% in a region from 5 ns after a pulse rises to 400 ns by using an optical pulse stretcher disposed in an optical path of the first pulse laser beam to stretch a pulse width of the first pulse laser beam, and irradiating alkali-free glass to be processed with the second pulse laser beam.
A glass processing method according to still another viewpoint of the present disclosure includes generating a plurality of pulse laser beams each having a wavelength ranging from 248 nm to 266 nm by using a plurality of laser oscillators at different timings, generating a combined pulse laser beam having an energy ratio greater than or equal to 91% but smaller than or equal to 99% in a region from 5 ns after a pulse rises to 400 ns by using a propagation optical system configured to parallelize optical path axes of the plurality of pulse laser beams to combine the plurality of pulse laser beams with one another, and irradiating alkali-free glass as an object to be processed with the combined pulse laser beam.
Embodiments of the present disclosure will be described below only by way of example with reference to the accompanying drawings.
1. Description of terms
2. Overview of laser processing system
3. Description of excimer laser apparatus according to Comparative Example
4.3 Factors contributing to high processing rate achieved by pulse laser beam having long pulses
4.4 Relationship between OPS circulation distance and TIS
4.5 Relationship between reflectance of beam splitter in OPS and TIS
5.3 Relationship between the number of OPSes, pulse waveform, and TIS
8. Example of preferable conditions for pulse laser beam
9. Wavelength of pulse laser beam
10. Hardware configuration of laser controller
Embodiments of the present disclosure will be described below in detail with reference to the drawings. The embodiments described below show some examples of the present disclosure and are not intended to limit the contents of the present disclosure. Furthermore, all configurations and operations described in the embodiments are not necessarily essential as configurations and operations in the present disclosure. The same component has the same reference character, and no redundant description of the same component will be made.
“TIS” stands for an indicator of the pulse width of a pulse laser beam and is expressed by Expression (1) below.
TIS=[∫I(t)dt]2/∫I(t)2dt (1)
The term I(t) in Expression (1) is a time function of the optical intensity (intensity) of the pulse laser beam.
That is, let I(t) be the optical intensity of the temporal waveform of the pulse laser beam at time t, and TIS is the pulse width defined by Expression (1). TIS is known as a method for defining the pulse width of a time function, of the intensity, that is a non-rectangular wave. TIS may be referred, for example, to as a “TIS pulse time width” or a “TIS width”.
The glass object GL as a processing target (workpiece) is placed on the XYZ stage 66. The XYZ stage 66 is a stage provided with an actuator and movable in the directions of three axes perpendicular to one another, an axis-X direction, an axis-Y direction, and an axis-Z direction. The excimer laser apparatus 10 is, for example, a KrF excimer laser that outputs a laser beam having a wavelength of 248 nm and an ArF excimer laser that outputs a laser beam having a wavelength of 193 nm.
The laser processing system 1 irradiates the aperture or mask 60 with a pulse laser beam outputted from the excimer laser apparatus 10 and forms an image of the aperture or mask 60 at the glass object GL via the reduction transfer optical system 64 to process the glass object GL. The thus configured laser processing system 1 allows simultaneous formation of a plurality of microscopic holes. In place of the configuration shown in
The excimer laser apparatus 10 includes a laser oscillator 12, a monitor module 16, and a laser controller 20. The laser oscillator 12 includes a chamber 120, a rear mirror 126, and an output coupling mirror 128. The output coupling mirror 128 may, for example, be a partially reflective mirror having a reflectance ranging from 8% to 15%. The output coupling mirror 128 and the rear mirror 126 are arranged so as to constitute an optical resonator.
The chamber 120 is disposed in the optical path of the optical resonator. The chamber 120 includes a pair of electrodes 130a and 130b, and two windows 134 and 136, which transmit the laser beam. An excimer laser gas is supplied into the chamber 120 from a gas supply source that is not shown. The excimer laser gas contains, for example, a rare gas, a halogen gas, and a buffer gas. The rare gas may, for example, be an Ar or Kr gas. The halogen gas may, for example, be an F2 gas, and the buffer gas may, for example, be an Ne gas.
The monitor module 16 is disposed in the optical path of the pulse laser beam outputted from the laser oscillator 12. The monitor module 16 includes a beam splitter 162, a condenser lens 163, and a photosensor 164.
The beam splitter 162 is disposed in the optical path of the pulse laser beam. The beam splitter 162, the condenser lens 163 and the photosensor 164 are so disposed that the light reflected off the beam splitter 162 is incident on the photosensor 164 via the condenser lens 163.
The photosensor 164 is so disposed that a light receiver of the photosensor 164 is located at the focal point of the condenser lens 163. The photosensor 164 may, for example, be a photodiode or a bi-plane-structured photoelectric tube that responds at high speed.
When discharge occurs between the electrodes 130a and 130b in the chamber 120, the excimer laser gas is excited, and a pulse laser beam amplified by the optical resonator including the output coupling mirror 128 and the rear mirror 126 is outputted via the output coupling mirror 128.
Part of the pulse laser beam outputted from the laser oscillator 12 is reflected off the beam splitter 162 in the monitor module 16 and incident on the photosensor 164 via the condenser lens 163.
The laser controller 20 receives a signal from the photosensor 164 and integrates the pulse temporal waveform carried by the signal to calculate the pulse energy.
The laser controller 20 controls the voltage applied to the space between the electrodes 130a and 130b in the laser oscillator 12 in such a way that the pulse energy measured with the photosensor 164 is equal to target pulse energy.
The method for directly processing glass to form a microscopic hole with an excimer laser has a problem of a low processing rate (processability) and hence a high processing cost.
The OPS 100 includes a beam splitter BS1 and four concave mirrors 101, 102, 103, and 104. The other configurations may be the same as those in
The concave mirrors 101, 102, 103, and 104 constitute an optical delay path of the pulse laser beam reflected off a first surface of the beam splitter BS1. The four concave mirrors 101 to 104 may be concave mirrors having substantially the same focal lengths. A focal length f of each of the concave mirrors 101 to 104 may correspond, for example, to the distance from the beam splitter BS1 to the concave mirror 101.
The concave mirror 101 is disposed so as to reflect the pulse laser beam reflected off the first surface of the beam splitter BS1 and be incident on the concave mirror 102. The concave mirrors 101 and 102 are disposed so as to cause the pulse laser beam reflected off the first surface of the beam splitter BS1 to transfer an image at the first surface of the beam splitter BS1 as a first image at equal magnification (1:1).
The concave mirror 103 is disposed so as to reflect the pulse laser beam reflected off the concave mirror 102 and be incident on the concave mirror 104. The concave mirror 104 is disposed so as to cause the pulse laser beam reflected off the concave mirror 104 to be incident on a second surface of the beam splitter BS1, that is the surface opposite from the first surface. The concave mirrors 103 and 104 are disposed so as to cause the first image to transfer as a second image at equal magnification at the second surface of the beam splitter BS1.
When discharge occurs in the chamber 120 of the laser oscillator 12, the excimer laser gas is excited, and a pulse laser beam generated by the optical resonator, which includes the output coupling mirror 128 and the rear mirror 126, is outputted via the output coupling mirror 128. The pulse laser beam having exited via the output coupling mirror 128 enters the OPS 100, which extends the pulse width of the pulse laser beam.
That is, the pulse laser beam having entered the OPS 100 is incident on the first surface of the beam splitter BS1. The beam splitter BS1 transmits part of the pulse laser beam incident on the first surface of the beam splitter BS1, and the transmitted pulse laser beam exits out of the OPS 100 as a zero-circulation pulse laser beam that has not circulated on the optical delay path. The zero-circulation beam is synonymous with no-circulation beam and is also called a “through beam”.
On the other hand, out of the pulse laser beam incident on the first surface of the beam splitter BS1, the pulse laser beam reflected off the first surface of the beam splitter BS1 enters the optical delay path and is reflected off the concave mirrors 101 to 104. Part of the pulse laser beam incident from the concave mirror 104 on the second surface of the beam splitter BS1 is reflected off the second surface of the beam splitter BS1, and exits out of the OPS 100 as a one-circulation pulse laser beam having circulated on the optical delay path once. The one-circulation pulse laser beam exits later by a delay period Δt1 than the zero-circulation pulse laser beam. The delay period Δt1 can be expressed as Δt1=LOPS/c, where LOPS represents the optical path length (circulation distance) of the optical delay path of the OPS 100, and c represents the speed of light.
Out of the pulse laser beam incident from the concave mirror 104 on the second surface of the beam splitter BS1, the pulse laser beam that the beam splitter BS1 has transmitted further enters the optical delay path, is reflected off the four concave mirrors 101 to 104, and is incident on the second surface of beam splitter BS1. The pulse laser beam reflected off the second surface of the beam splitter BS1 then exits out of the OPS 100 as a two-circulation pulse laser beam having circulated on the optical delay path twice. The two-circulation pulse laser beam exits later by the delay period Δt1 than the one-circulation pulse laser beam.
After the beam repeatedly circulates on the optical delay path as described above, the OPS 100 outputs a pulse laser beam as a result of superposition of the pulses of the beams having circulated none, once, twice, three times, and so on on one another. The optical intensity of the circulation beam that exits out of the OPS 100 decreases as the number of circulations of the optical delay path increases.
The one-circulation beam and the following beams are each delayed by an integer multiple of the delay period Δt1 from the zero-circulation beam, combined with one another, and outputted from the OPS 100, so that the pulse waveforms of the circulation beams including the no-circulation beam are superimposed on one another with time differences. The pulse width of the pulse laser beam is thus extended by the OPS 100.
The pulse laser beam having passed through the OPS 100 passes through the monitor module 16 and is outputted from the excimer laser apparatus 10A. The pulse laser beam having exited via the output coupling mirror 128 is an example of the “first pulse laser beam” in the present disclosure. The pulse laser beam having the pulse width stretched by the OPS 100 is an example of the “second pulse laser beam” in the present disclosure.
On the other hand, assuming in the excimer laser apparatus 10A according to the first embodiment, for example, that the beam splitter BS1 of the OPS 100 has a reflectance of is 60%, and the circulation distance is 7 m, TIS of the pulse laser beam outputted from the excimer laser apparatus 10A is extended to about 74 ns. The pulse laser beam that exits out of the OPS 100 has a pulse waveform having the pulses of the no-circulation beam and the pulses of each circulation beam having circulated on the optical delay path at least once, the pulses successively combined with one another, and the entire combined pulse waveform can be a single irradiation pulse.
Extending TIS from 32 ns to 74 ns therefore provides the effect of increasing the processing rate and reducing the number of pulses required for the processing by 25%.
Similarly, a regression line RL62 is derived from the relationship between the fluence of the pulse laser beam having the TIS of 62 ns and D2, and a regression line RL74 is derived from the relationship between the fluence of the pulse laser beam having the TIS of 74 ns and D2. The regression line RL62 shows that the processing threshold Fth is 17.0 J/cm2 when the pulse laser beam has the TIS of 62 ns, and the regression line RL74 shows that the processing threshold Fth is 12.8 J/cm2 when the pulse laser beam has the TIS of 74 ns.
Extending TIS from 32 ns to 62 ns therefore reduces the fluence required for the processing by 6% and hence provides the effect of increasing the processing area by 6% for the same pulse energy. Extending TIS from 32 ns to 74 ns reduces the fluence required for the processing by 29% and hence provides the effect of increasing the processing area by 29% for the same pulse energy.
To investigate factors contributing to the high processing rate achieved by the pulse laser beam having long pulses each having an extended pulse width as compared with the processing rate achieved by the pulse laser beam (TIS: 32 ns) according to Comparative Example, changes in the quantity of pulse laser beam absorbed by the glass over time was measured.
The measurement was performed by moving the glass object GL, which was the processing target object, in the direction of the optical path axis of the pulse laser beam to change the relative distance between the condenser lens 52 and the glass object GL so that the quantity of defocus of the pulse laser beam and hence the fluence thereof were changed. When the pulse laser beam is defocused, a low-fluence condition in which the fluence is smaller than the processing threshold is achieved. It may be understood that changes in the quantity of transmitted light over time that are observed when the pulse laser beam is defocused corresponds to changes in the intensity of the pulse laser beam over time with which the glass object GL is irradiated.
Comparison between the graphs G1 and G2 clearly shows that the quantity of transmitted light is large only at the beginning of the high-fluence first pulse. A conceivable reason for this is that the glass object GL is altered and the quantity of absorbed light increases after the beginning of the first pulse.
When the absorption coefficient of the glass is fixed, the two waveforms are believed to have the same shape, but they are not the same as shown in
The same phenomenon as that in
In the technical field of laser drilling of glass, narrowing the pulse width of the laser beam is believed to be beneficial. However, in view of the situation in which the small value of the transmitted light quantity ratio associated with the glass object GL is reset in a very short period after the falling edge of an irradiation pulse, as indicated by the result shown in
From the findings based on
The pulse end time of “400 ns” is determined from the viewpoint of a period long enough for the energy of the pulse laser beam to become zero. The pulse waveform of the pulse laser beam outputted from the OPS 100 varies depending on the specific configuration of the OPS 100 and other factors. Therefore, after a pulse rises, the period required for the energy to become zero depends on the waveform of the pulse. A variety of pulse waveforms are conceivable. In consideration of a practical configuration, the energy of the pulse laser beam can be zero in 400 ns at the latest after a pulse rises. In the present disclosure, the energy ratio in the region from 5 ns after a pulse rises to the end of the pulse is evaluated by determining the energy ratio in the region from 5 ns after the pulse rises to 400 ns.
Increasing the reflectance of the beam splitter BS1 in the OPS 100 to a value greater than or equal to 40% allows extension of TIS, as shown in
Further increasing the reflectance of the beam splitter BS1 in the OPS 100 to a value greater than 40% allows extension of TIS to 74 ns. Increasing the reflectance of the beam splitter BS1 in the OPS 100 to a value greater than or equal to 40% further allows the energy ratio in the region from 5 ns after a pulse rises to 400 ns to increase to a value greater than or equal to 91% but smaller than or equal to 99%.
Examination under the condition of the energy ratio in the region from 5 ns after a pulse rises to 400 ns in place of the condition of TIS for the graphs shown in
The OPS 100 described in the first embodiment has a form in which the optical delay path is formed by the four concave mirrors 101 to 104, but the configuration of the OPS is not limited thereto. For example, the optical delay path can be formed by six concave mirrors or eight or more concave mirrors.
The excimer laser apparatus 10B includes a plurality of OPSes, the OPS 100 and an OPS 200, in the optical path between the laser oscillator 12 and the monitor module 16. In the excimer laser apparatus 10B, the OPS 200 is disposed on the optical path between the OPS 100 and the monitor module 16.
The OPS 200 includes a beam splitter BS2 and four concave mirrors 201 to 204. The OPS 200 may have the same configuration as that of the OPS 100 described in
The pulse laser beam outputted from the OPS 100 enters the OPS 200. The pulse width of the pulse laser beam having entered the OPS 200 is further extended by the OPS 200. The OPS 200 operates in the same manner in which the OPS 100 operates. The beam splitter BS2 and the concave mirrors 201 to 204 of the OPS 200 play the same roles of the corresponding elements of the OPS 100.
TIS can be further extended by disposing the plurality of optical pulse stretchers 100 and 200 directly in the optical path of the pulse laser beam. The configuration in which two OPSes are disposed is presented by way of example, but the number of OPSes is not limited to two and can be three or more.
TIS is extended to 155 ns by disposing the two OPSes, and the energy ratio in the region from 5 ns after a pulse rises to 400 ns is improved to 98%, as shown in
TIS is extended to 259 ns by disposing the three OPSes, and the energy ratio in the region from 5 ns after a pulse rises to 400 ns is improved to 99%.
TIS is extended by employing the configuration in which one or more OPSes are disposed as described above, whereby the energy ratio in the region from 5 ns after a pulse rises to 400 ns can be increased, resulting in an increase in the processing rate.
Since energy loss greatly increases as the number of OPSes is increased to three or more, it is preferable to use one or two OPSes.
The glass processing method according to the second embodiment allows grater extension of the pulse width than in the first embodiment, and the energy ratio in the region from 5 ns after a pulse rises to 400 ns can therefore be increased, whereby the processing rate is further improved.
The laser apparatus 10C includes a solid-state laser apparatus 12C and a wavelength converter 13 in place of the laser oscillator 12 in
The wavelength converter 13 is disposed in the optical path between the solid-state laser apparatus 12C and the OPS 100. The wavelength converter 13 may be disposed in the optical path between the OPS 100 and the monitor module 16, but is preferably disposed upstream from the OPS 100, as shown in
The wavelength converter 13 may include two second harmonic generation (SHG) crystals or one fourth harmonic generation (FHG) crystal. The nonlinear optical crystal disposed in the wavelength converter 13 may, for example, be an LBO (LiB3O5) or CLBO (CsLiB6O10) crystal. The combination of the solid-state laser apparatus 12C and the wavelength converter 13 is an example of the “laser oscillator” in the present disclosure.
The pulse laser beam outputted from the solid-state laser apparatus 12C is converted by the wavelength converter 13 into a pulse laser beam having a wavelength of 257.5 nm, which is the wavelength of the fourth harmonic of a pulse laser beam having the wavelength of 1030 nm, or a pulse laser beam having a wavelength of 266 nm, which is the wavelength of the fourth harmonic of a pulse laser beam having the wavelength of 1064 nm.
The pulse width of the pulse laser beam outputted from the wavelength converter 13 is extended by the OPS 100.
The laser apparatus 10C according to the third embodiment, which generates the pulse laser beam having the UV wavelength of 257.5 nm or 266 nm, which is substantially equal to 248 nm, which is the wavelength at which a KrF excimer laser apparatus oscillates, can provide the same effects as those provided by the first embodiment.
The laser system 10D includes the plurality of laser oscillators 41, 42, and 43, a delay circuit 50, the monitor module 16, a laser controller 20D, highly reflective mirrors 71 and 72, and knife-edge mirrors 81 and 82. A propagation optical system including the highly reflective mirrors 71 and 72 and the knife-edge mirrors 81 and 82 is an example of the “propagation optical system” in the present disclosure. The highly reflective mirror 71 is an example of the “first mirror” in the present disclosure, and the highly reflective mirror 72 is an example of the “second mirror” in the present disclosure. The knife-edge mirror 81 is an example of the “first knife-edge mirror” in the present disclosure, and the knife-edge mirror 82 is an example of the “second knife-edge mirror” in the present disclosure.
The laser oscillators 41, 42, and 43 may, for example, each have the same configuration as that of the laser oscillator 12 in
The highly reflective mirror 71 and the knife-edge mirror 81 are disposed in the optical path of a first pulse laser beam PL1 outputted from the laser oscillator 41. The highly reflective mirror 71 is disposed so as to reflect the first pulse laser beam PL1 and cause the reflected beam to be incident on the knife-edge mirror 81. The knife-edge mirror 81 is disposed so as to reflect the first pulse laser beam PL1 incident via the highly reflective mirror 71 and cause the optical path axis of the reflected first pulse laser beam PL1 to be parallel to the optical path axis of a second pulse laser beam PL2 outputted from the laser oscillator 42.
The highly reflective mirror 72 and the knife-edge mirror 82 are disposed in the optical path of a third pulse laser beam PL3 outputted from the laser oscillator 43. The highly reflective mirror 72 is disposed so as to reflect the third pulse laser beam PL3 and cause the reflected beam to be incident on the knife-edge mirror 82. The knife-edge mirror 82 is disposed so as to reflect the third pulse laser beam PL3 incident via the highly reflective mirror 72 and cause the optical path axis of the reflected third pulse laser beam PL3 to be parallel to the optical path axis of the second pulse laser beam PL2.
The first pulse laser beam PL1, the second pulse laser beam PL2, and the third pulse laser beam PL3 having traveled via the knife-edge mirrors 81 and 82 travel along the optical paths parallel to each other, and are partially reflected off the beam splitter 162 in the monitor module 16, pass through the condenser lens 163, and are incident on the photosensor 164.
The delay circuit 50 receives light emission delay periods at the laser oscillator 41, 42, and 43 from the laser controller 20D and outputs light emission trigger signals to the laser oscillators 41, 42, and 43 at light emission timings corresponding to the light emission delay periods.
The laser oscillator 41 is an example of the “first laser oscillator” in the present disclosure. The laser oscillator 42 is an example of the “second laser oscillator” in the present disclosure. The laser oscillator 43 is an example of the “third laser oscillator” in the present disclosure. The laser oscillators 41, 42, and 43 are denoted as a “laser oscillator 1”, a “laser oscillator 2”, and a “laser oscillator 3”, respectively, in
The laser controller 20D preferably sets the delay periods Td1, Td2, and Td3 in such a way that the energy ratio in the region from 5 ns after a pulse rises to 400 ns in the combined pulse laser beam that is the combination of the first pulse laser beam PL1, the second pulse laser beam PL2, and the third pulse laser beam PL3 is greater than or equal to 91% but smaller than or equal to 99%. The delay periods may be set so as to satisfy a relationship Td1<Td2<Td3.
Thereafter, in step S12, the laser controller 20D sets target pulse energy values of the pulse laser beams to be outputted from the plurality of laser oscillators 41, 42, and 43. Let E1 be the target pulse energy of the first pulse laser beam PL1 (first target pulse energy), E2 be the target pulse energy of the second pulse laser beam PL2 (second target pulse energy), and E3 be the target pulse energy of the third pulse laser beam PL3 (third target pulse energy), and the laser controller 20D sets, for example, as follows: E1=70 mJ; E2=100 mJ; and E3=100 mJ. The target pulse energy values may be set so as to satisfy a relationship E1<E2<E3.
Thereafter, in step S13, the laser controller 20D transmits the light emission trigger signals to the delay circuit 50.
Thereafter, in step S14, the delay circuit 50 transmits the light emission trigger signals to the laser oscillators 41, 42, and 43 in accordance with the delay period settings.
Thereafter, in step S15, the laser controller 20D evaluates whether the processing target object has been processed. When the result of the evaluation in step S15 is No, the laser controller 20D returns to step S13. On the other hand, when the result of the evaluation in step S15 is Yes, the laser controller 20D terminates the flowchart of
The pulse waveform PW1 of the first pulse laser beam PL1 is an example of the “first pulse” in the present disclosure. The pulse waveform PW2 of the second pulse laser beam PL2 is an example of the “second pulse” in the present disclosure. The pulse waveform PW3 of the third pulse laser beam PL3 is an example of the “third pulse” in the present disclosure.
Let Du1 be the pulse duration from the rise to fall of the pulse in the pulse waveform PW1 of the first pulse laser beam PL1, Du2 be the pulse duration from the rise to fall of the pulse in the pulse waveform PW2 of the second pulse laser beam PL2, and Du3 be the pulse duration from the rise to fall of the pulse in the pulse waveform PW3 of the third pulse laser beam PL3, and the following relationship is preferably satisfied.
Td2<(Td1+Du1)
Td3<(Td2+Du2)
As described above, when a subsequent pulse of a plurality of successive pulses partially overlaps with a preceding pulse, the entire combined waveform of the combination of the plurality of pulses can generate a combined pulse laser beam having a pulse duration Td3+Du3−Td1. According to the contents described above with reference to
The combined pulse laser beam produced by combining the pulse waveforms PW1, PW2, and PW3 with one another at the knife-edge mirrors 81 and 82 is an example of the “combined pulse laser beam” in the present disclosure.
The laser system 10D according to the fourth embodiment, which combines the plurality of pulse laser beams outputted from the plurality of laser oscillators 41, 42, and 43, can generate a combined pulse laser beam having the energy ratio greater than or equal to 91% but smaller than or equal to 99% in the region from 5 ns after a pulse rises to 400 ns, whereby the same effects as those provided in the first to third embodiments can be provided.
As described in the first to fourth embodiments, a preferable range of TIS of the pulse laser beam is greater than or equal to 62 ns but smaller than or equal to 259 ns, more preferably, greater than or equal to 62 ns but smaller than or equal to 155 ns, still more preferably, greater than or equal to 62 ns but smaller than or equal to 74 ns.
The preferable range of the energy ratio in the region from 5 ns after a pulse rises to 400 ns is greater than or equal to 91% but smaller than or equal to 99%, more preferably, greater than or equal to 91% but smaller than or equal to 95%.
It has been ascertained that the processing rate is improved by setting the energy ratio in the region from 5 ns after a pulse rises to 400 ns for the pulse laser beams having wavelengths ranging from 248 nm to 266 nm at a value greater than or equal to 91% as described above.
On the other hand, when an ArF excimer laser apparatus (wavelength: 193 nm) is used, no significant change in the processing rate has been observed even when the pulse width (TIS) is changed.
In the wavelength range shorter than 248 nm or longer than 266 nm, it is speculated that there may be wavelengths at which improvement in the processing rate is expected as the wavelengths from 248 nm to 266 nm, but the wavelength conditions at such wavelengths have not empirically been ascertained.
To the present inventor's current knowledge, it is believed that a unique phenomenon occurs at least under the condition where alkali-free glass is irradiated for processing with a pulse laser beam having a wavelength ranging from 248 nm to 266 nm, including a representative pulse laser beam from a KrF excimer laser apparatus (wavelength of 248 nm). Based on the novel findings described above, the technology according to the present disclosure achieves improvement in the processing rate by using a pulse laser beam having a specific wavelength range (248 nm to 266 nm).
The laser controllers 20 and 20D can each be realized by using one or more processors. The processor is a processing apparatus including a storage device that stores a control program and a CPU (central processing unit) that executes the control program. The processor is particularly configured or programmed to carry out a variety of processes described in the present disclosure.
The storage device is a tangible, non-transitory computer readable medium, including, for example, a memory that is a primary storage device and a storage that is an auxiliary storage device. The computer readable medium may, for example, be a semiconductor memory, a hard disk drive (HDD) device, or a solid state drive (SSD) device, or a combination of a plurality of the components described above. The program to be executed by the processor is stored in the computer readable medium.
Part of the processing functions of the laser controllers 20 and 20D may be achieved by using an integrated circuit represented by an FPGA (field programmable gate array) and an ASIC (application specific integrated circuit).
The description above is intended to be illustrative and the present disclosure is not limited thereto. Therefore, it would be obvious to those skilled in the art that various modifications to the embodiments of the present disclosure would be possible without departing from the spirit and the scope of the appended claims. Further, it would be also obvious for those skilled in the art that embodiments of the present disclosure would be appropriately combined.
The terms used throughout the present specification and the appended claims should be interpreted as non-limiting terms. For example, terms such as “comprise”, “include”, “have”, and “contain” should not be interpreted to be exclusive of other structural elements. Further, indefinite articles “a/an” described in the present specification and the appended claims should be interpreted to mean “at least one” or “one or more.” Further, “at least one of A, B, and C” should be interpreted to mean any of A, B, C, A+B, A+C, B+C, and A+B+C as well as to include combinations of any thereof and any other than A, B, and C.
The present application is a continuation application of International Application No. PCT/JP2020/038617, filed on Oct. 13, 2020, the entire contents of which are hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2020/038617 | Oct 2020 | US |
| Child | 18180495 | US |
