Multiple beam drilling system

(Cross-reference of related applications) US Provisional Patent Application No. 61 / 020, 273 dated January 10, 2008, "Multiple Laser Beam Positioning and Energy Delivery System", the disclosure of which is described in this specification. It is used as a reference in the document, and its priority is claimed based on Articles 1.78 (a) (4) and (5) (i) of the US Patent Law Enforcement Regulations (CFR).

This application relates to the PCT patent application "Multiple Mirror Calibration System" filed on the same day and assigned to the assignee of the present invention, and the disclosure contents thereof are also incorporated herein by reference.

The present invention relates comprehensively to a drilling apparatus, specifically to multiple holes using a laser beam.

For many years, laser beams have been used in manufacturing systems that operate for the purpose of drilling, melting, or cutting objects such as substrates. Multiple laser beams can be used in such systems to reduce manufacturing time. However, there is a need to improve the operational flexibility of well-known systems that use multiple beams for perforation.

The present invention provides an improved system and method for laser perforating a substrate with varying simultaneity.

According to a preferred embodiment of the invention, a laser is run to generate a single output beam with a beam pulse having a total energy, said single. A method in which the output beam is divided into a plurality of beams over time (to an extent which varies over time), and the plurality of beams are applied to a plurality of drilling positions on the substrate, and laser drilling is performed on the substrate with various simultaneities. The corresponding plurality of beams among the plurality of beams having pulse energy occupying the first fraction of the total energy (using corresponding). Ones of the plural beams), the first parts of multiple holes, and then at least the second proportion (ratio, portion) of the total energy, which is different from the first proportion. , Fraction) (a second At least one second part of at at least one of the plurality of holes, using at least one of the plurality of beams each having pulse energy occupying a fraction. Methods are provided that include drilling the least one of said multiple holes).

According to a preferred embodiment of the present invention, the first ratio is a function of the number of holes.

According to a preferred embodiment of the present invention, the second ratio is a function of the number of holes in which at least the second portion is perforated.

Further, according to a preferred embodiment of the present invention, a laser is operated to generate a single output beam having a total power, and a plurality of the single output beams are generated over time. This is a method of performing laser perforation on a substrate with various simultaneities by dividing the beam into multiple beams and irradiating the plurality of beams to a plurality of perforation positions on the substrate. The first portion of the plurality of holes is simultaneously perforated using the corresponding plurality of beams among the plurality of beams having the beam power occupying the fraction), and then the total power different from the first ratio is obtained. A method of perforating at least one second portion of at least one of the plurality of holes using at least one of the plurality of beams, each of which has a beam power that occupies at least a second proportion of the above. Is provided.

According to a preferred embodiment of the present invention, the first ratio is a function of the number of holes.

According to a preferred embodiment of the present invention, the second ratio is a function of the number of holes in which at least the second portion is perforated.

Preferably, the single output beam comprises a plurality of pulses having a single beam pulse energies generated at a pulse repetition rate. A pulse in which the corresponding plurality of beams out of the plurality of beams perforating the first portion of the plurality of holes occupy the first ratio of the pulse repetition rate and the single beam pulse energy. Includes multiple pulses with energy. Further, at least one of the plurality of beams perforating at least one second portion of at least one of the plurality of holes has the pulse repetition rate and the single beam pulse energy. Includes a plurality of pulses having at least the pulse energy occupying the second proportion. Alternatively, at least one of the plurality of beams perforating at least one second portion of at least one of the plurality of holes is a sub-multiple of the pulse. repetition A plurality of pulses having rate) and pulse energies which are a function of the single beam pulse energies are included, and the fractions and functions are the first. It is selected according to the ratio of 2.

According to a preferred embodiment of the present invention, the single output beam comprises a plurality of pulses having a single beam pulse energy generated at a certain pulse repeat rate, the first portion of the plurality of holes. The corresponding plurality of beams among the plurality of beams to be perforated are the first fraction of the pulse repeat rate selected according to the first ratio and the first of the single beam pulse energies. Includes a plurality of pulses having pulse energies that are a function of 1. Further, at least one beam of the plurality of beams perforating at least one second portion of at least one of the plurality of holes is the second divisor of the pulse repetition rate and the single beam. A plurality of pulses having a pulse energy, which is a second function of the pulse energy, are included, and the second divisor and the second function are selected according to the second ratio.

A deeper understanding of the present invention can be obtained by referring to the following detailed description of the embodiments shown together with the drawings. A brief description of the drawings is as follows.

<figref num="1">It is the schematic schematic diagram of the multiple drilling apparatus by embodiment of this invention.</figref><figref num="2A">It is the schematic schematic diagram which showed the different operation mode of the acoustic optical deflector by embodiment of this invention.</figref><figref num="2B">It is the schematic schematic diagram which showed the different operation mode of the acoustic optical deflector by embodiment of this invention.</figref><figref num="2C">It is the schematic schematic diagram which showed the different operation mode of the acoustic optical deflector by embodiment of this invention.</figref><figref num="3A">It is a schematic schematic diagram which showed various steps in the drilling process of the 1st substrate by embodiment of this invention.</figref><figref num="3B">It is a schematic schematic diagram which showed various steps in the drilling process of the 1st substrate by embodiment of this invention.</figref><figref num="3C">It is a schematic schematic diagram which showed various steps in the drilling process of the 1st substrate by embodiment of this invention.</figref><figref num="3D">It is a schematic schematic diagram which showed various steps in the drilling process of the 1st substrate by embodiment of this invention.</figref><figref num="3E">It is a schematic schematic diagram which showed various steps in the drilling process of the 1st substrate by embodiment of this invention.</figref><figref num="3F">It is a schematic schematic diagram which showed various steps in the drilling process of the 1st substrate by embodiment of this invention.</figref><figref num="3G">It is a schematic schematic diagram which showed various steps in the drilling process of the 1st substrate by embodiment of this invention.</figref><figref num="3H">It is a schematic schematic diagram which showed various steps in the drilling process of the 1st substrate by embodiment of this invention.</figref><figref num="3I">It is a schematic schematic diagram which showed various steps in the drilling process of the 1st substrate by embodiment of this invention.</figref><figref num="4A">It is a schematic schematic diagram which showed various steps in the drilling process of the 2nd substrate by embodiment of this invention.</figref><figref num="4B">It is a schematic schematic diagram which showed various steps in the drilling process of the 2nd substrate by embodiment of this invention.</figref><figref num="4C">It is a schematic schematic diagram which showed various steps in the drilling process of the 2nd substrate by embodiment of this invention.</figref><figref num="4D">It is a schematic schematic diagram which showed various steps in the drilling process of the 2nd substrate by embodiment of this invention.</figref><figref num="4E">It is a schematic schematic diagram which showed various steps in the drilling process of the 2nd substrate by embodiment of this invention.</figref><figref num="4F">It is a schematic schematic diagram which showed various steps in the drilling process of the 2nd substrate by embodiment of this invention.</figref><figref num="4G">It is a schematic schematic diagram which showed various steps in the drilling process of the 2nd substrate by embodiment of this invention.</figref><figref num="4H">It is a schematic schematic diagram which showed various steps in the drilling process of the 2nd substrate by embodiment of this invention.</figref><figref num="4I">It is a schematic schematic diagram which showed various steps in the drilling process of the 2nd substrate by embodiment of this invention.</figref><figref num="5">FIG. 5 is a schematic flowchart showing steps performed in a processing unit for drilling a substrate according to an embodiment of the present invention.</figref>

With reference to FIG. 1, FIG. 1 is a schematic view schematically showing a multiple perforation apparatus 20 according to an embodiment of the present invention. The entire device 20 is controlled by the processing unit 36, which is typically operated by the operator of the device.

The processing unit 36 typically comprises a general purpose computer processor, which is programmed in software to perform the functions described herein. This software can be downloaded to the processor in electronic form, for example, via a network. Alternatively or additionally, the software may be provided on a tangible medium such as an optical storage medium, a magnetic storage medium, or an electronic storage medium. Further, instead, at least some of the functions of the processor may be executed by dedicated hardware or programmable hardware.

The apparatus 20 includes a set of selectably directable mirrors 38, and the directions of the variable mirrors in each direction are generated by the processing unit 36. It is individually controlled by a command or command. In this specification, variable directional mirrors are also referred to as "orientable mirrors" and are steering mirrors for the beams incident on the mirrors. Functions as mirrors). The device 20 can be used as a laser drilling facility, where the multiple (multiple) directional mirrors drill multiple holes in the substrate 44 mounted on the movable table 42. In order to do this, each laser subbeam (respective laser) is performed during the production stage of the above equipment. It is used to align the direction of sub-beams). The substrate 44 may be either a single-layer substrate or a multilayer substrate. It will be appreciated that in the production phase, the equipment can be used for similar processes other than drilling, such as cutting and / or processing materials. In the following description, different substrates 44 are distinguished by adding different characters to the identification code 44 of the substrate, if necessary. Table 42 can be moved in the x, y, and z directions orthogonal to each other according to the received command from the processing unit 36.

The device 20 comprises a laser 22, which is typically a solid-state laser, producing a single beam 24 of pulses at ultra-violet wavelength. .. The beam parameters, including their overall energy, are set according to the instructions from the processing unit 36. In the following description, as an example, it is assumed that the laser 22 generates pulses (plural) of a single beam 24 at a fixed repetition rate F [Hz], and each pulse has a total energy Et [J]. Therefore, the beam has an average power of P = EtF [W]. In one embodiment of the invention, the beam pulses have a width of approximately 30 ns. The pulses (plural) are generated at a fixed repeat rate F100 kHz, and each pulse has a total energy Et100 [μJ], so the average power of the beam is P10 [W]. Normally, almost all the energy of the laser pulse is used in the above production stage.

The beam 24 passes through the cylindrical lens 26, where it is focused into a substantially parallel beam, where the parallel beam travels to the Acousto-Optic Deflector (AOD) 28. The AOD28 receives a radio frequency (RF) drive input from the processing unit 36. This RF input diffracts the incident collimated laser beam into one or more sub-beams 29. The sub-beam 29 is usually generated in a two-dimensional plane. The processing unit 36 can select the number of the sub-beams and the energy distribution between the sub-beams by changing the parameters of the RF input with respect to the AOD 28. An example of AOD that can be used in the embodiment of the present invention is the part MQ180-A0,2-UV manufactured by AA Optoelectronic of Saint-Remy-Les-Chevreuse, France.

To generate one or more sub-beams 29, the processing unit 36 can operate the AOD 28 in a number of different modes. The sub-beam will have different characteristics in different modes. These different modes of operation and the different possible characteristics of generated sub-beams 29 are described in more detail below in connection with FIGS. 2A, 2B, and 2C. To do.

The plurality of sub-beams 29 are sent to the first mirror group 32 by the relay lens 30. The mirrors 32 are oriented so that each incident beam is reflected toward the second mirror group 34 as a three-dimensional sub-beam group 41. For clarity, only the path 39 of one of the three-dimensional sub-beams is shown in FIG. In the following description, each beam of the sub-beam group 41 is distinguished by a subscript as necessary. Therefore, as shown in FIG. 1, when 20 mirrors 34 and 20 mirrors 38 are present, the sub-beam group 41 includes 20 sub-beams 41A, 41B, ..., 41T. In the following description, where appropriate, the corresponding characters are also added to the elements that need to be distinguished. For example, first a sub-beam 41B is generated from a sub-beam 29B. The sub-beam 41B is then sequentially reflected by the mirrors 32B and 34B, and finally by the orientable mirror 38B. The mirror groups 32 and 34 are typically fixed in position and orientation, and are configured such that the reflected three-dimensional sub-beams from the mirror group 34 are substantially parallel to each other.

The 3D sub-beam group reflected by the mirror group 34 is sent to the orientable mirror group 38. Optical elements for beam adjustment and relay are provided between the mirror group 32, the mirror group 34, and the mirror group 38, and are schematically shown by the lens 35 in FIG. 1 for the sake of clarity. There is. Due to these beam adjustment and relay optical elements, the sub-beam group reflected by the mirror group 38 becomes parallel and collimated and narrow. These optics are controlled by the processing unit 36 to generate sub-beam groups of different diameters as needed. In the following description, the elements (configuration) of the device 20 that generates the sub-beam group 41, that is, the elements 22, 26, 28, 30, 32, 34, and 35 are also referred to as the sub-beam generation system 33.

Each mirror of mirror group 38 is coupled to each steering assembly in a set of mounts, and the steering assembly is referred to herein as an adjustable mount. Call it 43. Each mount 43 of the above mount group is individually controlled by the processing unit 36. The processing unit 36 can direct the orientation of a particular mount, and thus the mirror coupled to the mount, within a range according to the characteristics of that mount. The mount group and the mirror group connected to the mount group are configured so that the sub-beam group reflected by the mirror group is substantially orthogonal to the surface of the movable table 42. Typically, the mount group 43 implements two-axis mirror steering using galvanometric elements to which the mirror group 38 is attached.

2A, 2B and 2C are schematic views showing three different modes of operation of AOD28 according to the embodiment of the present invention. The first two modes can be realized by an AOD such as the AA Optoelectronic AOD illustrated above. In all modes, the incident laser beam, the direction of the acoustic wave traveling in the AOD, and one or more sub-beams generated by the acoustic wave are in a single plane.

In the first mode shown in FIG. 2A, the processing unit 36 generates an RF signal having an amplitude A1 and a frequency F1. The RF signal constitutes an acoustic wave, which causes the AOD28 to function as a diffraction grating having a single pitch. The grid deflects the incident laser beam 24 from the lens 26 (FIG. 1) by an angle α1 to form a single sub-beam 29. The processing unit 36 can change the angle α1 by changing the value of the frequency F1. Further, the energies of the pulses (plurality) in the sub-beam can be changed by changing the amplitude A1.

In the first mode, the AOD typically operates under a beam transfer efficiency (η) of up to approximately 90%, and thus the single sub-beam pulses by varying the value of A1. The energy of is E = ηEt. Here, Et is the pulse energy of the beam 24, and η 0.9. The remaining energies are undeflected pulse energy and low efficiency higher harmonics. The unbiased pulse energy is usually absorbed by a beam dump. The repetition rate of the pulse (plurality) of the single sub-beam is the same as the repetition rate of the pulse (plurality) of the beam 24, and the average power of the sub-beam is ηP. Where P is the average power of the beam 24.

In the second mode shown in FIG. 2B, the processing unit 36 generates a combined RF signal having two or more different frequencies F1, F2, .... The second mode of operation is described in DL Hecht's paper "Multifrequency acoustooptic deffraction", IEEE Trans. Sonics Ultrasonics SU-24 (1), 7-18 (1977).

For simplicity, only the effects of two different frequencies are shown in FIG. 2B. The processing unit 36 generates each of the frequencies whose amplitudes are A1, A2, .... When the processing unit 36 generates different frequencies of the RF signal, the AOD28 effectively functions as a multi-pitched diffraction grating, and the RF input causes the acoustic wave to travel in the AOD. In this case, the incident laser beam 24 is divided into a large number of sub-beams 29A, 29B, ... Corresponding to the number of different frequencies F1, F2, .... The angles α1, α2, ... Of each sub-beam of the sub-beam group are determined by the frequencies F1, F2, ..., Respectively.

The energies Ea and Eb of the pulses (plural) of each sub-beam can be expressed as Ea = ηaEt and Eb = ηbEt (ηa &lt;1, ηb &lt;1). Typically, due to the characteristics of the AOD, the total pulse energy of the exiting beams can be reduced to about 70% or less, and therefore Ea + Eb 0.7Et here. Within this overall constraint, the processing unit 36 can change the pulse energy of each of the sub-beams by changing the amplitude value of each RF frequency, here A1 and A2. As in the first mode, any unbiased energy can be absorbed by the beam dump. The pulse repetition rate of the outgoing sub-beams is the same as the pulse repetition rate of the incident beam, and if the average power of the incident beam is P, the average power of each sub-beam is Pa = ηaP and Pb = It is given by ηbP.

In the third mode shown in FIG. 2C, the processing unit 36 generates an RF signal that effectively divides the AOD 28 into two or more grids with different pitches. In order to realize this third mode, the operating window of the AOD needs to be extended from the values normally available in "commercial" acoustic-optical deflectors such as the illustrated AOD. .. With the above expansion, different gratings can be formed in the AOD in an "adjacent" form (in a "side-by-side" manner). A person skilled in the art will be able to determine the amount of the extension and the requirements for producing the extension without conducting more experiments than necessary.

For simplicity, the following description of the third mode assumes that AOD28 is effectively divided into two grids. The RF signal for the third mode has two frequency components F1 and F2, each of which has an amplitude of A1 and A2. Unlike the RF input of the second mode, the RF input for the third mode does not combine the frequency components as in the second mode, but alternates between different frequency components.

In the third mode, a beam splitter (not shown in FIG. 2C) in front of the AOD28 splits the incident beam 24 into two beams 24A and 24B. The beam splitter is typically an optical beam splitter and can have any suitable split ratio, such as 50:50. Alternatively, another AOD typically configured to operate in the second mode described above may be used as the beam splitter. If the beam 24 has pulse energies Et, the beams 24A and 24B have pulse energies aEt and bEt, respectively. Here, a and b satisfy a and b &lt;1, and the values of a and b are unique to the beam splitter.

The beams 24A and 24B are deflected according to their respective pitches by a different grating, as described above for the first mode. The sub-beams 29C and 29D resulting from the third mode of operation have pulse energies Ec and Ed given by Ec = aηaEt and Ed = bηbEt (ηa &lt;1, ηb &lt;1), respectively. Similar to the first mode, the values of ηa and ηb can be changed by changing the values of A1 and A2, respectively, and typically have a maximum value of about 0.9. Further, when the incident average beam power is P, the average power of the sub beam is given by Pc = aηaP and Pd = bηbP.

Further, as in the first and second modes, any unbiased energy in the third mode can be absorbed by the beam dump.

In the description of the above three modes of operation of the AOD28, the sub-beam output from the AOD28 has the same pulse repeat rate, ie, the same frequency as the incident beam 24. However, this is not a necessary condition, and in one embodiment of the present invention, the processing unit 36 is such that the frequency of the sub-beam output is a sub-multiple of the input frequency. Adjusts the RF input to the AOD. For example, in the system shown in FIG. 2A, the processing unit 36 may alternately switch the input frequency to the AOD28 between F1 and F2 according to the pulse repetition rate of the beam 24. As a result, the dispersion of the pulse from the beam 24 is switched between the angles α1 and α2, and the frequency of the pulse output in each of the sub-beams becomes half the pulse frequency of the beam 24.

Here, the pulse energies (plural) may be substantially the same as the incident pulse energies (plural). However, the average sub-beam power is significantly different from the average incident beam power due to the decrease in the repetition rate of the pulses (plural) in the sub-beams. For example, if the incident beam has a pulse energy Et and an average power P, and the values of A1 and A2 are set so that the pulses (plural) of each sub-beam have the same energy ηEt, the pulse repetition is performed. Due to the halving of the return rate, the average power of the sub-beams is ηP / 2.

Allowing the pulse repeat rate of the sub-beams to be set to a divisor of the pulse repeat rate of the incident beam provides additional flexibility in drilling a particular material. Since the pulse energy is typically the parameter that most affects the material, as illustrated above, the average power of the sub-beam while keeping the pulse energy substantially equal to the incident beam. Is convenient when drilling materials. For example, lowering the above average power extends the cooling time between pulses (reducing the average power provides extra cooling time between pulses).

In addition to the various sub-beams described above, the processing unit 36 adjusts the parameters of the RF input to the AOD to effectively set the energy of each pulse, thereby overall the overall of any particular sub-beam. The energy profile can be tailored over time. For example, in the first mode, the processing unit does not abruptly change the energy of the sub-beam pulses (plurality) due to a sudden change in A1, but the energy decreases linearly over a large number of pulses. It may be configured as follows. A ramped linear decrease with such a gradient can be used to prevent the metal such as copper from being unintentionally removed from the substrate layer.

Considering the above description of the operation of the AOD28, it can be seen that the apparatus 20 provides a system in which the processing unit 36 can change the number of laser subbeams 29 that are used simultaneously at any specific time. In addition, the processing unit 36 can select the percentage of pulse energy in each sub-beam 29 and adjust the overall energy profile at the time of each sub-beam. , And the pulse frequency of each sub-beam 29 can be set to the same frequency as the incident beam 24 or a divisor thereof.

The following description shows various ways to effectively drill different substrates by varying the number of sub-beams, the pulse energy in each sub-beam, and the characteristics of the sub-beams in device 20. An example is provided. As shown below, the time required to drill different substrates can be minimized by varying the number of beams, pulse energy and beam characteristics. In the following description, the processing unit 36 is composed of an arbitrary single sub-beam having a maximum sub-beam pulse energy Em and a plurality of sub-beams having a pulse energy less than Em by the processing unit 36. It shall be possible to generate it.

Further, although the three-layer substrate is used as an example in the following description, it can be naturally applied to drilling or processing a substrate having two layers or any other number of layers by making changes as necessary. ..

3A-3I are schematic views of various stages in a time progression of drilling according to an embodiment of the present invention. 3A-3I are schematic cross sections of the substrate 44A, where FIG. 3A corresponds to the first stage and FIG. 3I corresponds to the last stage. The substrate shall have an upper first layer 102 that is relatively difficult to perforate, a second layer 104 that is easy to perforate, and a third layer 106 that is not perforated. Further, it is assumed that four holes 110, 112, 114 and 116 having substantially the same diameter, that is, having the same diameter, are drilled in the substrate. However, the two holes 114 and 116 shall have the lower bound on the upper surface 108 of the layer 104, which is finished in the first process. The other two holes 110 and 112 shall have a lower boundary finished in a different second process.

As an example, the four holes 110, 112, 114 and 116 are the four separated sub-beams 41A, 41B, 41C and 41D reflected by the mirrors 38A, 38B, 38C and 38D, respectively. Shall be perforated by. As mentioned above, the sub-beams 41A, 41B, 41C and 41D are formed from the sub-beams 29A, 29B, 29C and 29D, respectively.

Since layer 102 is difficult to perforate, the processing unit 36 first uses one sub-beam at a. time) Perforate layer 102. Each sub-beam has a pulse energy Em. For example, each sub-beam is assumed to be generated by operating the AOD28 in a first mode (see FIG. 2A) and sequentially supplying different frequencies F1, F2, F3 and F4 to the AOD. Sub-beams 29A, 29B, 29C, and 29D are sequentially generated by different frequencies, forming sub-beams 41A, 41B, 41C, and 41D, respectively. The processing unit 36 sequentially irradiates the sub-beams 41A, 41B, 41C and 41D reflected by the mirrors 38A, 38B, 38C and 38D, respectively, to perforate the holes 110, 112, 114 and 116 in the layer 102. To do. As shown in FIG. 3A, the layer 102 at the location of the hole 110 is first drilled. Then, as shown in FIGS. 3B, 3C and 3D, the layers 102 at the positions of holes 112, 114 and 116 are sequentially drilled. Sub-beams with pulse energy Em are used respectively. FIG. 3E shows the state of the substrate 44A after all four holes have been drilled in the layer 102.

Since the layer 104 is easy to drill and all four holes can be accessed for drilling, the processing unit 36 is the same as when the layer 102 is drilled, as shown in FIG. 3F. Two sub-beams 41A, 41B, 41C and 41D are operated simultaneously. These four sub-beams have the total sub-beam energy E available._availableA ratio (ratio) 1 / 4E that is substantially equal_availableIt shall be used in. These four sub-beams operate the AOD28 in a second mode (see FIG. 2B) by the processing unit and combine frequencies F1, F2, F3 and F4 for each frequency, each with amplitudes A1, A2, A3 and A4. Is formed simultaneously by giving the AOD an RF input with.

The amplitudes A1, A2, A3, and A4 are selected so that the pulse energies of the respective sub-beams are substantially the same, but the second mode has different characteristics from the first mode described above. E_availableIs typically found to be less than Em. The four sub-beams pierce layer 104 with mirrors 38A, 38B, 38C and 38D, and piercing with these four sub-beams pierces the layer 104 with the appropriate depth required. Perforation continues until all four sub-beams are completed.

In the next drilling step shown in FIG. 3G, the processing unit 36 operates the AOD28 in a second or third mode with respect to holes 114 and 116 by 1 / 4E._availableOperate sub-beams 41C and 41D with a greater than approximately equal fractional pulse energies Ef. Drilling of holes 114 and 116 continues until the holes reach the top surface 108. In one example, at this point the perforations of holes 114 and 116 are finalized. This finish is, by way of example, applied by reducing the energies of the two sub-beams from Ef to zero. When the energies of the two sub-beams for holes 114 and 116 decrease, the processing unit 36 increases the pulse energies of the sub-beams 41A and 41B for holes 110 and 112 from 0 to Ef, causing holes 110 and 112. Perforation may be initiated. The energy reduction and increase are achieved by giving the AOD28 an appropriate RF input by the processing unit, as described above.

As shown in FIG. 3H, the processing unit continues to drill holes 110 and 112 using pulse energy Ef until it reaches the top surface 108. In one example, the processing unit 36 shall maintain the pulse energy at Ef until the required finishing of the top surface 108 is complete. When finishing is complete, the processing unit finishes drilling holes 110 and 112. The completed hole is shown in FIG. 3I.

4A-4I are schematic views showing various stages in the drilling process of the substrate 44B according to the embodiment of the present invention. 4A-4I are schematic cross-sections of substrate 44B, where FIG. 4A corresponds to the first stage and FIG. 4I corresponds to the last stage.

Substrate 44B shall have an upper first layer 202, which is relatively difficult to perforate, a second layer 204, which is easy to perforate, and a third layer 206, which is not perforated. Further, it is assumed that eight holes 209, 210, 212, 214, 216, 218, 220 and 222 are drilled in the substrate. As an example, it is assumed that the holes 212, 214, 216, 218, 220 and 222 have the same diameter D1 and the holes 209 and 210 have the same diameter D2 larger than D1.

In one example, the eight holes 209, 210, 212, 214, 216, 218, 220 and 222 were eight separate (independent) reflected by mirrors 38A, 38B, 38C, 38D, 38E, 38F, 38G and 38H, respectively. ) Sub-beams 41A, 41B, 41C, 41D, 41E, 41F, 41G and 41H shall be perforated. Further, the sub beams 41A, ..., 41H are formed from the sub beams 29A, ..., 29H, respectively.

As shown in FIG. 4A, the processing unit 36 first drills a hole 209 with a sub-beam 41A having pulse energy E1 and diameter D2 oriented by mirror 38A. The perforation of layer 202 continues until it reaches the top surface 208 of layer 204, at which point the processing unit stops perforating hole 209.

As shown in FIG. 4B, the processing unit 36 then drills a hole 210 with a sub-beam 41B having pulse energy E1 and diameter D2 oriented by mirror 38B. This drilling continues until it reaches the top surface 208, at which point the processing unit stops drilling holes 210 and begins drilling holes 212 and 214.

Since the holes 212 and 214 have small diameters, the processing unit 36 drills both of these holes at the same time, as shown in FIG. 4C. To drill both holes, the processing unit produces two sub-beams 41C and 41D with the same pulse energy E2 and diameter D1. Here, E2 is a certain proportion (a fraction) of E1. Unit 36 uses two mirrors 38C and 38D to direct these sub-beams into each hole. Also, since the processing unit typically generates two sub-beams using the second mode of operation of the AOD28, the pulse repeat rate of these sub-beams is equal to the pulse repeat rate of the beam 24.

Alternatively, the two sub-beams may be generated by one or more of the other methods described above for AOD28. For example, the processing unit may operate the AOD28 in the first mode to switch between two different input frequencies. In this case, the two sub-beams 41C and 41D have the same pulse energy, but the pulse repeat rate is half the pulse repeat rate of the beam 24.

Drilling of holes 212 and 214 continues until each hole reaches top surface 208.

As shown in FIG. 4D, when the holes 212 and 214 reach the top surface 208, the processing unit stops drilling and begins drilling holes 216 and 218. To drill holes 216 and 218, the processing unit 36 produces two sub-beams 41E and 41F and uses two mirrors 38E and 38F to orient these sub-beams. The method of generating these sub-beams is typically as described above for the sub-beams 41C and 41D. Drilling of holes 216 and 218 continues until each hole reaches top surface 208.

As shown in FIG. 4E, when the holes 216 and 218 reach the top surface 208, the processing unit stops drilling and begins drilling holes 220 and 222. To drill holes 220 and 222, the processing unit 36 produces two sub-beams 41G and 41H and uses two mirrors 38G and 38H to orient these sub-beams. The method of generating these sub-beams is typically as described above for the sub-beams 41C and 41D. Drilling of holes 220 and 222 continues until each hole reaches top surface 208.

At this point, all eight holes in layer 202 of substrate 44B have been drilled.

As shown in FIG. 4F, the processing unit then begins drilling holes 209 and 210 into layer 204. Since layer 204 is easier to drill than layer 202, the processing unit 36 uses two sub-beams 41A and 41B to provide approximately equivalent pulse energies in which these two sub-beams are smaller than E1. Set to have. The processing unit continues to drill holes 209 and 210 until it reaches the top surface 224 of layer 206, where it turns off the sub-beams 41A and 41B.

Once the holes 209 and 210 are completed as shown in FIG. 4G, the processing unit 36 orients the mirrors 38A and / or 39B, as needed, typically to subsequently drill other areas of the substrate 44B. Can be reoriented.

Layer 204 is easier to perforate than layer 202. For this reason, the processing unit 36 typically drills holes 212, 214, 216, 218, 220, and 222 in two batches of three, rather than in three batches of two. ..

As shown in FIG. 4G, the processing unit 36 first drills holes 212, 214 and 216. The processing unit produces three sub-beams 41C, 41D and 41E substantially as described above to perforate these holes, but each of these sub-beams has a certain percentage of E2 ( It has the same pulse energy E3, which is (a fraction). Alternatively, these three sub-beams may be generated by one or more of the other methods described above for AOD28, eg, switching between three different input frequencies. In this case, the three sub-beams 41C, 41D and 41E have almost the same pulse energy as E1, but the pulse repeat rate is 1/3 of the pulse repeat rate of the beam 24.

Once the holes 212, 214 and 216 have been drilled, the processing unit 36 can orient the mirrors 38C, 38D and / or 38E to drill other areas of substrate 44B, if desired.

As shown in FIG. 4H, the processing unit 36 then uses the sub-beams 41F, 41G and 41H with the parameters of the sub-beam used for drilling the layer 202 appropriately modified, and the process described above with reference to FIG. 4G. Drill holes 218, 220 and 222 in much the same manner as above. Once the drilling of these holes is complete, the processing unit 36 can orient the mirrors 38F, 28G and / or 38H as needed to subsequently drill other areas of the substrate.

FIG. 4I shows the final state of the substrate 44B in which all the holes are perforated.

FIG. 5 is a flowchart 250 showing steps performed in the processing unit 36 to drill the substrate 44 according to an embodiment of the present invention. Each step of this flowchart corresponds to the multi-hole drilling process described above with reference to FIGS. 3A-3I and 4A-4I.

In beam generation step 252, the processing unit 36 operates the laser 22 to generate a single output beam 24 in which the total energy of the beam pulses (plural) is EtJ, as described with reference to FIG. Generate. Normally, the pulse repetition rate is constant.

In beam splitting step 254, the processing unit 36 splits the single beam into two or more sub-beams by supplying an RF input to the AOD28. This single beam split is as illustrated above with reference to FIGS. 3F and 4C. As described above, this division allows the pulse energy of the sub-beam to be a fraction of the total energy Et of the beam 24.

In the first drilling step 256, the processing unit 36 simultaneously drills a part of each of the plurality of holes so that the sub-beams simultaneously drill a part of each of the plurality of holes, as described above with reference to FIGS. 3F and 4C. -Align the mirrors (plural) that reflect the beam (plural).

In sub-beam adjustment step 258, the processing unit uses the sub-beam so that at least one of the sub-beams has a different fractional energy from the pulse energy of step 254. -Adjust (change) the beam (plural).

In the second drilling step 260, the unit 36 supplies one or more adjusted or sub-beams to continue drilling each hole. The adjustment of the sub-beam is as illustrated above with reference to, for example, FIGS. 3G and 4G.

Typically, the processing unit 36 drills all the holes in a particular substrate by repeating all or part of the steps in Flowchart 250 as needed.

As a matter of course, the above-described embodiment is given as an example, and the present invention is not limited to the contents illustrated and described above. Rather, the scope of the present invention includes combinations and sub-combinations of the various features described above, as well as variations and improvements not disclosed in the prior art that can be conceived by those skilled in the art by interpreting the above description.