JP3404930B2 - Fine processing device and fine processing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fine processing technique, and more particularly to a technique for forming fine trench holes and the like with a high aspect ratio.

[0002]

2. Description of the Related Art Conventionally, a fine processing apparatus / method is a fine processing apparatus using a focused ion beam (FIB) (Shiokawa, Journal of Precision Engineering 55/2/1989, P32-36) (hereinafter FI
B machine) and a fine electric discharge machine. These are excellent methods for forming fine trench holes. F
The IB device realizes sub-μm level processing.
However, since the FIB device is processed by ions, there are various problems. Further, in the case of fine electric discharge machining, the machining target is limited to a conductive object. In both cases, since the residue generated during processing is a neutral substance, it is necessary to use an air flow or a liquid flow to remove this residue from the processing site, but if the diameter of the processing hole is small, it will be difficult to remove it. Since the FIB device is in a vacuum, it is difficult to remove it using a fluid and redeposition occurs, and there is a problem that these restrictions limit the processing.

Therefore, the group of the inventors is set forth in JP-A-6-68.
A proposal was made to solve the above-mentioned problems by the methods as shown in Japanese Patent Application No. 4 and Japanese Patent Application No. 5-120816 (Japanese Patent Application Laid-Open No. 6-310473). With this proposal, it has become possible to form fine holes having a higher aspect ratio than ever before.

The outline of the proposal is as follows. A laser beam made into an ultra-fine beam by a condenser lens is radiated through a quartz window to a predetermined place in the vacuum chamber where negative pressure or more is to be processed, and at the same time, a voltage is applied to the counter electrode to the work material. To charge the surface. Then, the material to be processed irradiated with the laser causes laser ablation, and atoms, ions, and electrons fly out from the processed portion. Since an electric field is applied to this area in the same direction as the laser beam direction,
Upon receiving the Coulomb force, the charged particles that have jumped out make a motion that is determined by the electric field strength, the amount of charge, the particle mass, and the like, and quickly move from the processing site. The atoms that have jumped out in neutrality are also ionized and moved away because they collide with the electrons that have jumped out. This means that the exhaust conductance is increased.

As a result, since no processing residue remains on the processed portion, the processing can be deeply formed within the reach of the laser beam,
Even a non-conductive material could be processed to form a high aspect ratio hole. As a general rule, there is no concern of contamination because etching is not performed with other substances, and there is an advantage that processing is efficiently performed because processing and residue removal are performed alternately by pulse operation.

[0006]

However, it is difficult to observe the hole depth of the high aspect ratio hole thus formed unless it is a through hole, and even if a monitor camera is installed, it is difficult to process the hole. It is impossible to detect the bottom of the inner hole, and it must be said that the condition of the machining space cannot be grasped at all. Therefore, conventionally, the actual processing is performed after the condition is set such that the degree of processing is determined in advance. The processing location is not limited to one, and it is necessary to determine the conditions for all locations. For that reason, it takes a lot of time and labor for processing, and there is a big problem in terms of manufacturing throughput.

Therefore, an object of the present invention is to provide a microfabrication apparatus capable of monitoring a machining site and performing machining control in micromachining using laser ablation.

[0008]

In order to solve the above problems, the structure of the present invention is such that a material to be processed is placed in a vacuum chamber and an electric field is applied to the material to be processed in a laser incident direction,
In a microfabrication apparatus for processing the material to be processed while forcibly excluding scattered particles of the material to be processed positively charged by laser ablation by an electric field applied to a counter electrode, a charge for discriminating the type of the charged particles. Particle type discrimination means, and controlling the scattering direction of the charged particles,
Controlling the laser ablation by providing a particle scattering control unit that guides the scattered charged particles to the charged particle type determination unit, and the charged particle type determination unit constantly monitors the state of the processing site during processing. Is.
The configuration of the related invention is characterized in that the particle scattering control means is a magnetic field applied in a direction perpendicular to the laser incident direction, or alternatively, the particle scattering control means is parallel to the laser incident direction, and It is characterized in that an electric field is applied on the counter electrode coaxially and in the opposite direction.

Further, in the structure of the method for realizing the above processing, the material to be processed is placed in a vacuum chamber, an electric field is applied to the material to be processed in the laser incident direction, and the material is positively charged by laser ablation. In the fine processing method of processing the processed material while forcibly excluding the scattered particles of the processed material by the electric field applied to the counter electrode, while controlling the scattering direction of the charged particles by the particle scattering control means, That is, the scattered charged particles are guided to a charged particle type discriminating means, the type of the charged particles is discriminated by the charged particle type discriminating means, and the laser ablation is controlled. The configuration of the related invention is that the particle scattering control means is one of electrostatic field application by a pair of electrode pairs, static magnetic field application by magnetic field generation means, or electrostatic field application and static magnetic field application. is there. Alternatively, the laser irradiation of the laser ablation is pulse-driven.

[0010]

[Function] When the exhaust conductance is increased during laser ablation to actively eject ions from the bottom of the processing hole, a part of charged particles such as an electric field or a magnetic field is used to control some charged particles in a mass analyzer or the like. Guide to charged particle detection means,
Detects which region of the material to be processed the charged particles emitted during processing belong to. As a result, the degree of processing or the processing depth is known, and the laser irradiation can be controlled. In the configuration of claim 2, the magnetic field is used as the particle scattering control means, and the charged particles can be guided to the charged particle detection means side without being directed to the objective lens side by the Lorentz force. Further, in the structure of the third aspect, since it is deflected by the electric field, it can be similarly guided to the charged particle detecting means. Further, according to the method of claim 4, the state of the processed portion as described above can be monitored, and the processing control can be facilitated. According to the method of claim 5, the charged particles are generated intermittently, and the charged particles do not remain as a residue in the processed portion.

[0011]

The present invention has the effect that the state during laser processing can be monitored and that processing can be performed without the need for preconditioning for the processing position, and the number of steps is greatly shortened. According to the configuration of claim 2, since it is easy to form a strong magnetic field with a permanent magnet or the like, the charged particles can be easily guided to the charged particle detection means, and such fine processing can be easily realized. Have. According to the third aspect of the invention, since the electric field application can be easily controlled, there is an advantage that fine adjustment of the introduction to the charged particle detection means is easy. Further, as in the prior art, it is possible to perform the machining and the residue removal alternately by the pulse operation, so the machining proceeds efficiently.

[0012]

EXAMPLES The present invention will be described below based on specific examples. FIG. 1 is a schematic cross-sectional view of a vacuum chamber (vacuum chamber) 1 for carrying out the present invention, in which a sample 4 as a material to be processed is placed between opposing electrodes 2 and 3 in the vacuum chamber 1 whose pressure is reduced by a vacuum pump (not shown). Is installed in. The lower counter electrode is called the lower electrode 2 and the upper counter electrode is called the upper first electrode 3. A laser beam 5 (hereinafter referred to as a laser beam) is transmitted through a transmission window 7 made of quartz or the like so as to form a processing hole perpendicularly to the surface of the sample 4.
Through the objective lens 6 and condensed to 2 μm or less for irradiation. The irradiation center line is the optical axis 10. The laser light 5 uses an ArF excimer laser device (not shown) having a wavelength of 193 nm to cause laser ablation on the sample 4. Further, the laser light 5 is movable in the horizontal direction so that it can irradiate a predetermined processing site. The counter electrodes 2 and 3 are arranged by a high-voltage power supply (not shown) so that an electric field is applied to the sample 4 in a vertical direction which is a processing direction, and the laser light 5 transmitted through the transmission window 7 is transmitted to the upper first electrode 3. The sample 4 is irradiated through the provided opening.

A static magnetic field 11 provided on the counter electrode is adapted to apply a magnetic field in a direction perpendicular to the optical axis direction 10, and the charged particles (scattered particle group) 8 jumping out from the sample 4 are statically moved. The magnetic field 11 is directed in a direction substantially perpendicular to the optical axis 10 and is introduced into a mass analyzer 9, which is a charged particle type analyzing means installed around the direction. In FIG. 1, the range of the magnetic field coil 12 for generating the static magnetic field 11 is shown by a rectangular dotted line.
The static magnetic field 11 does not need to be rectangular, and FIG. 1 is only a schematic diagram.

Further, in consideration of the case where the charged particles 8 cannot be introduced into the mass analyzer 9 due to a high velocity, the reverse deceleration electric field 14 is applied so as to decelerate the ejected charged particles. The second electrode 13 is provided on the upper side of the upper counter electrode 3 and reduces the speed of the charged particles 8. Since the voltage applied to the second electrode 13 is easy to adjust, it can be introduced into the mass spectrometer 9 by adjusting the voltage of the second electrode 13 without adjusting the static magnetic field strength.

Mass spectrometer 9 as means for analyzing charged particle type
The method using a quadrupole (quadrupole electrode) is small and lightweight and convenient. Since the principle and operation of the mass spectrometer 9 are conventionally known, detailed description thereof will be omitted.

The mass spectrometer 9 may be installed at any position corresponding to the traveling direction of the charged particles. For example, the detector of the mass spectrometer 9 is installed in the plane orthogonal to the laser optical axis 10 in the optical axis direction, and the magnetic field of the static magnetic field 11 is 3000 Gauss,
When the area has a diameter of 1 cm, the value of the deceleration electric field 14 is adjusted so that the translational kinetic energy of the ions becomes about 10 eV at the exit of the electric field 14, that is, the entrance of the static magnetic field 11. At this time, the turning radius of each ion is about 5 mm to 1 cm, though it depends on the type of ion.
It is considered that the course of the static magnetic field 11 is bent by about 90 ° and is introduced into the detection unit. At the same time, due to this action, the ionized charged particles are prevented from coming to the transmission window 7 and adhering thereto because the course of the ionization is bent. Conventionally, it is possible to prevent the charged particles from adhering to the transmission window 7 and forming a kind of vapor deposition film, thereby lowering the intensity of the incident laser light.

It is to be noted that what is detected by the mass spectrometer 9 is the type of the charged particles 8, and the element contained in the processed portion is detected and identified. Therefore, in order to know the condition of the processed part as the monitor means, it is necessary to know in advance what the material of the processed part is. Based on the material data, the element identification data obtained from the mass spectrometer 9 can be checked to determine the condition of the processed portion, and the processing can be controlled.

(Second Embodiment) FIG. 2 shows a deflection for applying a deflection electric field which applies an electric field in a direction perpendicular to the protruding charged particles 8 instead of the static magnetic field 11 given to the charged particles by Lorentz force. Since the electrode plate 15 is provided and the charged particles cannot be deflected as strongly as in the case of the static magnetic field 11, the charged particles 8 just fly in the mass analyzer 9 to the side of the objective lens 6. It is located toward the direction of coming. The charged particles 8 jump out from the sample 4 and then above the counter electrode 3 above, where they are subjected to Coulomb force from the electric field of the deflecting electrode, are deviated from the direction toward the objective lens 6, and are introduced into the mass spectrometer 9. It Therefore, the transparent window 7 is not directly contacted with the charged particles 8, and the transparent window 7 is not clouded to slow down the processing. That is, it also serves as an alternative to the excluding means for electromagnetically excluding the charged particles from hitting the transmission window 7.

For example, the kinetic energy of the charged particles 8 is 10
0eV, the distance between the plates of the deflection electrode plate 15 is 10mm, and the plate length is
If it is 10 mm, if a potential difference of 20 V is applied between the plates, the path can be bent by 30 °. The detector of the mass spectrometer 9 may be installed ahead of this.

As described above, since the type of the charged particles 8 is discriminated by the monitor means using the mass spectrometer 9,
When the machining status can be grasped and the required depth is reached, the machining is stopped or the machining site is changed. Therefore, it is not necessary to check the processing site in advance and adjust the processing time, and it is possible to directly judge the current state of the processing target from the processing situation and perform fine processing corresponding to errors.

[Brief description of drawings]

FIG. 1 is a schematic configuration cross-sectional view of a vacuum chamber for performing microfabrication according to the first embodiment.

FIG. 2 is a schematic configuration cross-sectional view of a vacuum chamber for performing fine processing according to a second embodiment.

[Explanation of symbols]

1 vacuum chamber 2 Counter electrode Counter electrode on 3 4 sample (workpiece material) 5 laser light 7 transparent window 8 charged particles 9 Mass spectrometer (charged particle detection means) 10 optical axes 11 static magnetic field 13 Second electrode 15 Deflection electrode plate

Continuation of front page (56) Reference JP-A-1-103840 (JP, A) JP-A-4-225513 (JP, A) JP-A-63-224233 (JP, A) JP-A-63-128632 (JP , A) JP-A 63-64024 (JP, A) JP-A 53-128097 (JP, A) JP-A 48-29096 (JP, A) JP-A 51-17096 (JP, A) JP-A 3-253586 (JP, A) JP 60-240394 (JP, A) JP 51-145294 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B23K 26/00 -26/42 H01L 21/302

Claims (6)

(57) [Claims] 1. A material to be processed is placed in a vacuum chamber, an electric field is applied to the material to be processed in a laser incident direction, and scattered particles of the material to be processed which are positively charged by laser ablation are opposed to each other. In a microfabrication device for processing the material to be processed while forcibly excluding it by an electric field applied to an electrode, a charged particle type determination unit that determines the type of the charged particles, and a scattering direction while controlling the scattering direction of the charged particles. Controlling the laser ablation by means of particle scattering control means for guiding the charged particles to the charged particle type discriminating means, wherein the charged particle type discriminating means constantly monitors the state of the processing site during processing. A microfabrication device. 2. The microfabrication device according to claim 1, wherein the particle scattering control means is a magnetic field applied in a direction perpendicular to the laser incident direction. 3. The particle scattering control means is an electric field in which an electric field is applied in parallel with the laser incident direction, coaxially with the counter electrode, and in the opposite direction. Fine processing equipment. 4. A material to be processed is placed in a vacuum chamber, an electric field is applied to the material to be processed in a laser incident direction, and scattered particles of the material to be processed which are positively charged by laser ablation are opposed to each other. In a microfabrication method for processing the material to be processed while forcibly excluding it by an electric field applied to an electrode, the scattering direction of the charged particles is controlled by a particle scattering control means, and the scattered charged particles are discriminated by the charged particle type. A microfabrication method, wherein the laser ablation is controlled by determining the type of the charged particles by the charged particle type determination means. 5. The particle scattering control means is based on either electrostatic field application by a pair of electrode pairs, static magnetic field application by magnetic field generation means, or electrostatic field application and static magnetic field application. The fine processing method according to claim 4. 6. The fine processing method according to claim 4, wherein the laser irradiation of the laser ablation is pulse-driven.