JP3768583B2 - Laser processing equipment - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a laser processing apparatus for processing a semiconductor device such as an IC or LSI, a liquid crystal display, a plasma display, or the like, particularly when removing a part of a conductor layer and an insulator layer in a semiconductor device. The present invention relates to a laser processing apparatus to be used.
[0002]
[Prior art]
Conventionally, a laser processing apparatus as disclosed in JP-A-8-010971 is known. In JP-A-8-010971, the laser processing apparatus uses a KrF excimer laser oscillator (oscillation wavelength 248 nm) or an ArF excimer laser oscillator (oscillation wavelength 193 nm) as a light source.
[0003]
Further, in addition to the above-mentioned Japanese Patent Application Laid-Open No. 8-010971, the laser processing apparatus disclosed in Japanese Patent Application Laid-Open No. 7-333514 applies a laser beam in order to prevent the laser beam from entering the human eye. The optical system leading to the workpiece was surrounded by a light-shielding member.
[0004]
[Problems to be solved by the invention]
However, in the laser processing apparatus disclosed in JP-A-8-010971, a KrF excimer laser oscillator or an ArF excimer laser oscillator is used as a light source, so that materials such as silicon dioxide having a large bond dissociation energy are removed. Had the problem of insufficient photon energy.
[0005]
In addition, in the laser processing apparatus disclosed in JP-A-7-333514 in addition to the above-mentioned JP-A-8-010971, oxygen in the air is absorbed by the laser beam, and ozone is generated. There was a risk of damaging parts.
[0006]
The present invention has been made in view of the above problems, and an object thereof is to provide a laser processing apparatus that can remove even a material having a relatively large bond dissociation energy.
[0007]
[Means for Solving the Problems]
Hereinafter, in this specification, F₂Laser light is F₂The laser beam emitted by the laser oscillator shall be said.
[0008]
  A laser processing apparatus according to the present invention is a laser processing apparatus that processes a workpiece by irradiating the workpiece with laser light,₂F emitting laser light₂Laser oscillator and F₂F from laser oscillator₂A light guide optical system for guiding laser light to the workpiece, a light shielding case in which the light guide optical system is housed and a gas discharge port for discharging gas is formed, and the F₂Protective cover for accommodating laser oscillator and light shielding case, and light shielding caseInsideSupply inert gas toAnd the inside of the light shielding case is in a pressurized state.Gas supply means for carrying out the protection cover from the gas outlet of the light shielding caseー insideLed gas toOf the protective coverDischarge outsideAnd the inside of the protective cover is in a negative pressure state.And an evacuation means for performing the above.
[0009]
  The laser processing apparatus is F₂The material is to be processed by laser light. Processing based on the principle of directly breaking the bonds between molecules constituting the material can be performed by laser light from a conventional KrF or ArF excimer laser oscillator.₂According to the laser beam, it is possible to cut even silicon dioxide such as a material having a high bond dissociation energy that could not be cut by a conventional laser beam. F₂Laser light is absorbed by oxygen in the air and may generate ozone.In this invention, an inert gas is supplied from a gas supply source into a light shielding case that houses the light guide optical system. The generation of ozone is prevented by replacing the air in the light shielding case with this inert gas. At this time, since the inside of the light shielding case is in a pressurized state, it is difficult for air to enter from the outside. Further, the gas in the light shielding case is discharged through the gas discharge port provided in the light shielding case, and the light shielding case is accommodated in the protective cover, and the gas in the protective cover is exhausted by the exhaust means.Negative pressure stateAnd so on. For this reason, the outside of the light shielding case is also filled with the inert gas, further preventing air from entering the light shielding case. Further, in the present invention, since the inert gas is supplied not in the protective cover but in the light shielding case, the air is replaced with the inert gas in a short time, thereby shortening the waiting time until processing is performed. It becomes possible.
[0010]
Moreover, it is preferable that the light shielding case has an oxygen sensor inside, and the supply amount of the inert gas from the gas supply source is adjusted based on the output of the oxygen sensor.
[0011]
By providing the oxygen sensor, it is possible to know the oxygen concentration in the light shielding case, and it is possible to adjust the supply amount of the inert gas from the gas supply source based on this oxygen concentration. For this reason, it becomes possible to supply an inert gas efficiently.
[0012]
Furthermore, the light shielding case preferably includes a microscope for observing the workpiece.
[0013]
  Further, it is preferable that an imaging means for imaging the workpiece is attached to the microscope.
  Further, the light shielding case has one end at the F side. ₂ A cylindrical member connected to a case of a laser device including a laser oscillator and having the other end connected to the microscope; and a housing case surrounding a part of the microscope, the cylindrical member being inactive Preferably, a gas supply port for supplying gas is formed, and the gas discharge port is formed in the housing case.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, a preferred embodiment of a laser processing apparatus according to the present invention will be described with reference to the drawings.
[0015]
FIG. 1 is a cross-sectional view of a substrate with an integrated circuit applied in a laser processing apparatus, and FIG. 2 is a perspective view of a laser processing apparatus according to an embodiment of the present invention. 3 is a schematic cross-sectional view of the laser processing apparatus of FIG. 2 taken along the line AA, and FIG. 4 is a block diagram showing the configuration of the laser processing apparatus.
[0016]
In this embodiment, as an example of the workpiece, a substrate 2 with an integrated circuit (ROM) as shown in FIG. 1 (hereinafter referred to as a substrate) is used. The substrate 2 has a silicon substrate 2a as a base, and a silicon dioxide insulating film 2b, an aluminum electrode 2c, a silicon dioxide interlayer insulating film 2d, an aluminum ground electrode 2e, and a silicon nitride protective film 2f are sequentially stacked thereon. . In the following description, the laser processing apparatus 1 of this embodiment is used to remove the silicon nitride protective film 2f, the aluminum ground electrode 2e, and the silicon dioxide interlayer insulating film 2d described above, and finally expose the aluminum electrode 2c. Shall.
[0017]
In FIG. 2, in order to perform the above-described laser processing, the laser processing apparatus 1 is placed on the top plate 6 of the desk 4 on the substrate 2.₂A laser device 8 for irradiating a laser beam; and F₂It is confirmed that the desired portion is irradiated with the laser beam, the microscope 10 for fixing the substrate 2 as the workpiece, and the F emitted from the laser device 8₂It has a light guide optical system 12 for guiding laser light and condensing it at a desired position on the substrate 2. Further, since vibrations during laser processing are problematic, it is preferable to provide a vibration isolation table 14 between the laser device 8 and the microscope 10.
[0018]
The laser device 8 is F₂F emitting laser light₂A laser oscillator 16 is included. F₂The reason why the laser oscillator (hereinafter referred to as a laser oscillator) 16 is used is to remove the silicon dioxide interlayer insulating film 2d of the substrate 2 which cannot be removed by a conventional ArF excimer laser oscillator or the like. F₂Since the laser light has a high photon energy depending on the wavelength, the bond between the molecules constituting the material can be directly broken.
[0019]
The laser oscillator 16 has an F wavelength of 157 nm.₂Oscillates laser light. For this reason, compared with the case where an ultraviolet, visible, or infrared laser is used, the heat dripping around the processing part and the carbonization of the processing part are suppressed, and sharp processing becomes possible. According to the laser oscillator 16, F₂The laser light is absorbed by 99.9% for the silicon nitride 2f having a thickness of 0.5 μm and absorbed by 98.2% for the silicon dioxide 2d having a thickness of 0.5 μm. Thus, F₂Most of the laser light is absorbed at the surface of the material. Also, silicon dioxide 2d having a bond dissociation energy of 9.0 eV can be melted and evaporated, and F₂By controlling the number of irradiation pulses of laser light, the processing depth can be adjusted.
[0020]
Further, F from the laser oscillator 16₂Laser light has a shorter pulse width and higher peak output than those from KrF excimer lasers and XeCl excimer lasers. For this reason, even if the light energy absorbed on the surface is converted into heat energy, the diffusion of heat is very small, and there is almost no influence of drooling in the area around the processed portion.
[0021]
Gas is required to operate the laser oscillator 16 of the laser device 8. This gas is F₂It is composed of a mixed gas of a gas and a rare gas, and is filled in a cylinder 18. The mixed gas is supplied to the laser oscillator 16 by piping. In FIG. 1, the cylinder 18 is arranged in a first cylinder chamber 20 a below the top plate 6 of the desk 4. In addition, another cylinder 22 filled with a purge gas is disposed in the first cylinder chamber 20a in order to purge the mixed gas remaining in the laser oscillator 16. Further, in order to discharge the mixed gas and purge gas in the laser oscillator 16, a vacuum pump 24 is disposed in the second cylinder chamber 20b adjacent to the first cylinder chamber 20a.
[0022]
The mixed gas and the purge gas are supplied to the laser oscillator 16 by appropriately adjusting the pressure and flow rate of the mixed gas and the purge gas by open / close valves and pressure reducing supply valves (not shown) provided in the cylinders 20a and 20b. Further, the main device 1 is provided with a main plug shut-off valve 26 so that the supply of the mixed gas and the purge gas can be stopped if the mixed gas and the purge gas leak in the laser oscillator 16. In addition, this laser processing apparatus 1 is also provided with the gas detector 28 which operates the main stopper shut-off device 26 when there is a gas leak. Also, the vacuum pump 24 is toxic F₂F to remove gas₂The mixed gas and the purge gas are sucked through the gas pipe 30 having the gas filter 29 and discharged through another gas pipe 32.
[0023]
Since the second cylinder chamber 20b communicates with the outside and the first cylinder chamber 20a, unnecessary gases in the first and second cylinder chambers 20a and 20b are exhausted to the outside of the laser processing apparatus 1. It is like that. Further, a door 34 is provided in front of the first and second cylinder chambers 20a and 20b for exchanging cylinders. Further, a moving roller 36 is attached below the desk 4 so that the entire laser processing apparatus 1 can be easily moved. Furthermore, a fixing stopper 38 is attached to the lower part of the desk 4 in order to firmly fix the laser processing apparatus 1 to the floor when not moving.
[0024]
As shown in FIGS. 2 and 3, F emitted from the laser device 8 described above.₂The laser light passes through the light guide optical system 12 and is guided to the substrate 2 fixed to the microscope 10. The light guide optical system 12 includes a first mirror 40, a variable attenuator 42, a second mirror 44, a variable slit 46, a third mirror 48, and an objective lens 50. A mask illumination light source 52 is provided on the back side of the second mirror 44 to illuminate the removal region of the substrate 2.
[0025]
As the second mirror 44, F from the laser oscillator 16 is used.₂A dichroic mirror is used so that the laser light is reflected and the light from the mask illumination light source 52 is transmitted. The second mirror 44 is disposed in parallel with the first mirror 40 and is disposed at an angle of 45 ° with respect to the top plate 6 in the present embodiment.
[0026]
As the variable attenuator 42, MgF₂Or CaF₂A substrate in which a dielectric multilayer film is coated is used, and it is rotatably mounted between the first mirror 40 and the second mirror 44, and the substrate 2 is irradiated with F.₂Adjust the laser beam output. F₂When adjusting the output of the laser beam, the variable attenuator 42 is rotated and F₂Change the incident angle of the laser beam. F₂The output of the laser light changes as shown in FIG. 6 with respect to the incident angle. The variable attenuator 42 may be manually rotated.₂In order to adjust the output of the laser beam with good reproducibility, it can be rotated using a motor (not shown).
[0027]
Furthermore, the light guide optical system 12 is F₂A variable slit 46 is provided between the second mirror 44 and the third mirror 48 in order to determine the removal region on the substrate 2 by the laser light. The removal region on the substrate 2 is confirmed by illuminating with the mask illumination light source 52. The removal area is adjusted by opening and closing a shutter (not shown) of the variable slit 46. Further, as the third mirror 48, F that has passed through the variable slit 46 is used.₂A dichroic mirror that reflects the laser light and the light from the mask illumination light source 52 is used. Further, the objective lens 50 has F reflected by the dichroic mirror.₂The laser beam is imaged on the removal region on the substrate 2. In the present embodiment, the magnification of the objective lens 50 is 55 times.
[0028]
The light guide optical system 12 described above is surrounded by a hollow light shielding case 54. The light shielding case 54 includes a tubular member 56, a microscope 10 connected to the tubular member 56, and a housing case 58 that houses the microscope 10. One end of the cylindrical member 56 is substantially airtightly connected to the case of the laser device 8, and the other end is substantially airtightly connected at an opening 59 formed in the upper portion of the microscope 10.
[0029]
A part of the microscope 10 is surrounded by a housing case 58 and is connected almost airtightly through an upper opening (not shown) of the housing case 58. The microscope 10 is provided with an XYZ stage 60 in order to adjust the position of the substrate 2. The XYZ stage 60 is provided on the storage case 58. These positions can be adjusted manually, but are preferably adjusted via the controller 62 as shown in FIG. Furthermore, a sample stage 64 is provided on the XYZ stage 60 in order to fix the substrate 2. Further, the microscope 10 is provided with an epi-illumination light source 66 for observing the surface of the substrate 2, and guides light from the epi-illumination light source 66 to the surface of the substrate 2 inside the microscope 10. A half mirror 68 that transmits the reflected light from the surface of the substrate 2 is provided. Further, as shown in FIG. 3, the laser processing apparatus 1 has a TV monitor 70, and in order to confirm an image of the surface of the substrate 2 on the TV monitor 70, a CCD is further provided above the microscope 10. A camera 72 is attached. In addition, the storage case 58 is provided with a door (not shown) that can be opened and closed so that an operator can install the substrate 2 on the sample stage 64 of the microscope 10.
[0030]
Of the light guide optical system 12 described above, the first mirror 40, the variable attenuator 42, the second mirror 44, and the variable slit 46 are attached to the inside of the cylindrical member 56, as shown in FIG. The mirror 48 and the objective lens 50 are attached to the inside of the microscope 10 and the lens revolver 76, respectively. The reason why the light guide optical system 12 is surrounded by the light shielding case 54 is mainly to prevent light leakage and ensure the safety of the operator.
[0031]
F₂Laser light is O in the air₂To absorb ozone and generate ozone. This ozone not only harms the human body but also damages the optical components that make up the optical system. For this reason, in this embodiment, the inside of the light shielding case 54, that is, the cylindrical member 56, the microscope 10, and the housing case 58 is F.₂Replacement with an inert gas that is not absorbed by the laser beam, such as nitrogen gas, is made. As shown in FIGS. 2 and 3, the nitrogen gas is supplied from a gas supply source 80 through a gas supply pipe 78. The gas supply source 80 is provided with a flow rate adjustment valve 82 for adjusting the flow rate of nitrogen gas supplied to the light shielding case 54 as necessary. Specifically, the supply amount of nitrogen gas is increased when it is desired to purge air in a short time, and is maintained constant when air is sufficiently purged. In the present embodiment, a mass flow controller is used as the flow rate adjustment valve 82. In this embodiment, nitrogen gas is used as the inert gas, but helium, argon, or the like may be used.
[0032]
In order to replace the inside of the light shielding case 54 with nitrogen gas, it is ideal that the nitrogen gas does not leak out as the light shielding case 54. However, in practice, it is difficult to completely seal the connection portion. In particular, the storage case 58 of the light shielding case 54 has a door that can be opened and closed to attach the substrate 2 to the sample stage 64 of the microscope 10 and the like, so that leakage of nitrogen gas from the storage case 58 is prevented. Can not. Therefore, in the present invention, as shown in FIGS. 2 to 4, the laser oscillator 16, the cylindrical member 56, the microscope 10 and the housing case 58 are entirely covered with a protective cover 84. The protective cover 84 has an exhaust duct 86 and an exhaust fan 88 serving as exhaust means at an opening formed in the protective cover 84 in order to circulate nitrogen gas leaked from the light shielding case 54 and internal air. Is attached. In addition, the protective cover 84 is provided with an access panel 90 so that an operator can put his / her hand in for placing the substrate 2 on the microscope 10 or the like.
[0033]
In FIG. 3, in order to distribute nitrogen gas as described above, a gas supply port 92 for supplying nitrogen gas is formed in the laser processing apparatus 1, particularly in the cylindrical member 56. The reason why the gas supply port 92 is formed in the cylindrical member 56 in this way is that nitrogen gas can be circulated more efficiently in a shorter time than when the gas supply port 92 is formed in the protective cover 84. Further, the accommodation case 58 is formed with a gas discharge port 94 for discharging gas in order to circulate nitrogen gas.
[0034]
There are various possible positional relationships between the gas supply port 92 and the gas discharge port 94. In order to efficiently purge air with nitrogen gas, as shown in FIG. It is preferable that the gas flows from the adjacent portion to the bottom of the housing case 58.
[0035]
When nitrogen gas is supplied from the gas supply port 92 of the cylindrical member 56, the nitrogen gas purges the air in the cylindrical member 56 and then purges the air in the microscope 10 through an opening formed in the lens revolver 76. Further, the storage case 58 is filled with nitrogen gas. The filled nitrogen gas flows into the protective cover 84 through the gas discharge port 94, and the nitrogen gas filled in the protective cover 84 is sent to the exhaust duct 86 by the exhaust fan 88 and discharged to the outside. At this time, the inside of the light shielding case 54 is in a pressurized state, and the inside of the protective cover 84 is in a negative pressure state. For this reason, even if nitrogen gas in the light shielding case 54 leaks into the protective cover 84, air in the protective cover 84 does not enter the light shielding case 54. In addition, although the purge of the air in the microscope 10 or the discharge of nitrogen gas was performed through the opening of the lens revolver 76, a flow path is provided in the objective lens 50 or a reflection type objective lens 50 having a hollow structure is used. Thus, nitrogen gas can be sprayed onto the surface of the substrate 2.
[0036]
FIG.₂F against concentration₂It is a graph which shows the light guide rate of a laser beam. The measurement was performed at an optical path length of 50 cm and an atmospheric pressure of 1 atm. As shown in FIG.₂When the concentration is relatively small, it does not change much, but O₂The concentration changes remarkably in the vicinity of 100 ppm. This is an O concentration around 100 ppm.₂O suddenly in concentration₂Is F₂It is absorbed by the laser beam and ozone is generated. In this way, the light guide rate may change abruptly at a certain concentration, and ozone may be generated. For this reason, this laser processing apparatus 1 includes O₂It is preferable to provide a sensor 96 or the like. O₂If there is a sensor 96, O displayed on it₂Based on the concentration, the flow rate of the nitrogen gas supplied to the light shielding case 54 can be adjusted by the flow rate adjusting valve 82, which is economical without wasting nitrogen gas. In addition, O₂The sensor 96 is preferably provided inside the housing case 58. This is because in the storage case 58, the door is often opened and closed because the substrate 2 is placed on the sample stage 64 and the like, and thus the exposure to oxygen is most frequent compared to the inside of the cylindrical member 56 and the microscope 10. Because.
[0037]
In this embodiment, O₂As the sensor 96, a sensor employing a diaphragm galvanic system is used. This O₂The sensor 96 detects the diaphragm in an electrolyte solution having an anode and a cathode.₂This is based on the fact that current flows when the light passes through. O₂As the sensor 96, ionized O, such as a zirconia type, is used.₂Detecting ionic conductivity when molecules penetrate the ceramic interior, O₂For example, a light wave interference method for measuring a change in interference fringes of light accompanying a change in optical refractive index due to density may be used.
[0038]
As shown in FIGS. 2 and 4, in order to use nitrogen gas more economically, O₂A control unit 98 that controls the laser oscillator 16 and the flow rate adjusting valve 82 described above may be provided based on the output of the sensor 96. In order to operate the control unit 98, the protective cover 84 is provided with an operation panel 100.
[0039]
The control unit 98 is O₂O in the housing case 58 detected by the sensor 96₂Concentration value is predetermined O₂If the concentration value is equal to or higher than the concentration value (hereinafter referred to as a specified value), the flow rate adjustment valve 82 is controlled to₂Nitrogen gas is allowed to flow at the maximum flow rate until the concentration value reaches the specified value. Further, the control unit 98 is connected to the O in the housing case 58.₂If the concentration reaches the specified value, the O₂The flow rate adjustment valve 82 is controlled so as to maintain the concentration, and the consumption of nitrogen gas is minimized. At this time, adjustment of the flow rate of nitrogen gas by the control unit 98 is performed by feedback control.
[0040]
In addition, the control unit 98 is O₂O in the housing case 58 detected by the sensor 96₂The laser oscillator 16 is controlled based on the density value. O in the storage case 58₂When the concentration is equal to or higher than the specified value, the interlock is activated to lock the oscillation operation of the laser oscillator 16. O in the storage case 58₂When the concentration is smaller than the specified value, the oscillation operation of the laser oscillator 16 is unlocked.
[0041]
In the housing case 58, the control unit 98 controls the flow rate adjustment valve 82 based on the output of a door opening / closing sensor (not shown) attached to the door of the housing case 58. In this case, when the control unit 98 detects that the door is opened by the door opening / closing sensor, the control unit 98 controls the flow rate adjustment valve 82 to stop the supply of nitrogen gas.
[0042]
In the above configuration, an example of the procedure for actually processing the substrate 2 will be described.
[0043]
First, after opening the access panel 90 of the protective cover 84 and further opening the door of the housing case 58, the substrate 2 is placed on the sample stage 64 of the microscope 10. When the substrate 2 is placed on the sample stage 64, the epi-illumination light source 66 is turned on. At this time, the state of the surface of the substrate 2 is observed by the TV monitor 70 connected to the CCD camera 72.
[0044]
Next, F irradiated to the surface of the substrate 2₂In order to know the shape and position of the laser light in advance, the mask illumination light source 52 is turned on and the slit pattern projected onto the surface of the substrate 2 is observed. Then, while watching the TV monitor 70, the controller 62 operates the XYZ stage 60 to determine the removal area on the substrate 2.
[0045]
Then, the vacuum pump 24 and the exhaust fan 88 are operated to exhaust the inside of the protective cover 84, and the inside of the protective cover 84 is brought into a negative pressure state. Subsequently, nitrogen gas is supplied from the gas supply source 80 by the flow rate adjusting valve 82. And O₂The sensor 96 allows O₂If the concentration falls below the specified value, F₂Irradiate with laser light.
[0046]
FIG. 6 shows the F for the variable attenuator 42.₂Laser beam incident angle and F₂It is a graph which shows the relationship with the relative output of a laser beam. F₂In irradiating the laser beam, first, depending on the type of material to be processed, based on FIG.₂Adjust the relative output of the laser beam. As mentioned above, F₂The relative output of the laser light can be adjusted by rotating the variable attenuator 42. Point A is the minimum F that can remove the silicon nitride protective film 2f.₂The relative output of the laser beam is shown. Accordingly, when it is desired to remove the silicon nitride protective film 2f, F₂The relative output of the laser beam may be made larger than the relative output corresponding to the point A.
[0047]
The point B is for the silicon dioxide interlayer insulating film 2d, and the point C is for the aluminum electrode films 2c and 2e. Again, F₂Each material can be removed by setting the relative output of the laser light to be equal to or greater than the relative output of each point.
[0048]
The processing of the substrate 2 is started by first removing the silicon nitride protective film 2f on the uppermost layer of the substrate 2. In this case, the F ground is not processed to the aluminum ground electrode layer 2e immediately below the silicon nitride 2f.₂The relative output of the laser beam is set between the relative output of point A and the relative output of point B. And the repetition frequency is 10 Hz, the pulse width is 2 nsec, the pulse energy is 1 mJ, and the peak output is 500 kW.₂Oscillate laser light. At this time, F is applied to the silicon nitride protective film 2f.₂When 30 pulses of laser light are irradiated, only the silicon nitride protective film 2f is removed, and the aluminum ground electrode 2e is exposed.
[0049]
Next, the exposed aluminum ground electrode layer 2e is removed. In this case, F₂The relative output of the laser light is set to be equal to or higher than the relative output corresponding to the point C, and F is used under the same conditions as the silicon nitride protective film 2f is removed.₂Oscillate laser light. At this time, F is applied to the aluminum ground electrode layer 2e.₂When one or two pulses of laser light are irradiated, only the aluminum ground electrode layer 2e is removed, and the silicon dioxide interlayer insulating film 2d immediately below is exposed without being damaged.
[0050]
Then, the silicon dioxide interlayer insulating film 2d is removed. In this case, F₂The relative output of the laser beam is set between the relative output of point B and the relative output of point C. Then, under the same conditions as the silicon nitride protective film 2f is removed, F₂Oscillate laser light. At this time, F is applied to the silicon dioxide interlayer insulating film 2d.₂When 50 pulses of laser light are irradiated, the target aluminum electrode layer 2c is exposed without being damaged.
[0051]
As mentioned above, although embodiment of this invention was described, according to the laser processing apparatus 1 which concerns on the said embodiment, besides glass nitride as a protective film, phosphorus glass and polyimide can be similarly removed, and as a metal film Titanium, chromium or tungsten can also be removed.
[0052]
In the above embodiment, F₂In order to adjust the output of the laser beam, adjustment is performed by the variable attenuator 42. However, adjustment is performed by controlling the voltage applied in the laser oscillator 16 by the control unit 98, or by using filters having different transmittances. You can also.
[0053]
【The invention's effect】
As described above, the laser processing apparatus according to the present invention is F₂F emitting laser light₂Since a laser oscillator is used, even a material having high bond dissociation energy that could not be removed by an ArF excimer laser or the like can be removed.
[0054]
In addition, since a replacement gas composed of an inert gas is introduced into the apparatus, the optical system constituting the apparatus is an O in air.₂F₂It is not damaged by the ozone generated when the laser light is absorbed. Therefore, the lifetime of the device can be extended.
[0055]
Furthermore, since the light shielding case has a double structure covered with a protective cover and the inside of the light shielding case and the inside of the protective cover are covered with an inert gas, the light shielding case does not need to have high sealing performance. Therefore, an inexpensive and simple device can be manufactured.
[0056]
In addition, laser processing equipment has O₂This sensor is installed₂Since the supply amount of the inert gas from the gas supply source can be adjusted based on the oxygen concentration value of the sensor, the inert gas can be used efficiently.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a substrate with an integrated circuit applied to a laser processing apparatus according to an embodiment of the present invention.
FIG. 2 is a perspective view of a laser processing apparatus according to an embodiment of the present invention.
FIG. 3 is a cross-sectional view of the laser processing apparatus of FIG.
FIG. 4 is a perspective view showing a configuration of a laser processing apparatus according to an embodiment of the present invention.
FIG. 5 shows F against oxygen concentration.₂It is a graph which shows the light guide rate of a laser beam.
FIG. 6 shows F for variable attenuator.₂Laser beam incident angle and F₂It is a graph showing the relationship with the relative output of a laser beam.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Laser processing apparatus, 2 ... Board | substrate (workpiece), 10 ... Microscope (light-shielding case), 12 ... Light guide optical system, 16 ... F₂Laser oscillator 24 ... exhaust fan (exhaust means) 54 ... light shielding case 56 ... cylindrical member (light shielding case) 58 ... accommodating case (light shielding case) 72 ... CCD camera (imaging means) 80 ... gas supply source 84 ... Protective cover, 94 ... Gas outlet, 96 ... O₂sensor.

Claims (5)

In a laser processing apparatus for processing the workpiece by irradiating the workpiece with laser light,
And _{F 2} laser oscillator which emits a F ₂ laser light,
A light guide optical system for guiding F ₂ laser light from the F ₂ laser oscillator to the workpiece;
A light shielding case in which the light guide optical system is housed and a gas discharge port for discharging gas is formed;
A protective cover that houses the F ₂ laser oscillator and the shielding case therein,
Supplying an inert gas into the shielding case, a gas supply means for the interior of the light shielding case and pressurized state,
And exhaust means for the said guided from the gas outlet to the interior of the protective cover gas shielding case is discharged to the outside of the protective cover, the inside of the protective cover and the negative pressure state,
A laser processing apparatus comprising:   The laser processing apparatus according to claim 1, wherein the light shielding case includes an oxygen sensor therein, and an amount of inert gas supplied from the gas supply source is determined based on an output of the oxygen sensor. .   The laser processing apparatus according to claim 1, wherein the light shielding case includes a microscope for observing the workpiece.   The laser processing apparatus according to claim 3, wherein an imaging unit for imaging the workpiece is attached to the microscope. One end of the light shielding case is the F ₂ A cylindrical member connected to a case of a laser device including a laser oscillator and having the other end connected to the microscope; and a housing case surrounding a part of the microscope; The laser processing apparatus according to claim 3, wherein a gas supply port for supplying gas is formed, and the gas discharge port is formed in the housing case.

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