WO2011043357A1

WO2011043357A1 - Irradiation method of laser, frequency adjustment method of piezoelectric vibrator using same, and frequency-adjusted piezoelectric device using same

Info

Publication number: WO2011043357A1
Application number: PCT/JP2010/067501
Authority: WO
Inventors: 耕三多田; 伊藤　義郎
Original assignee: シチズンファインテックミヨタ株式会社; 国立大学法人長岡技術科学大学
Priority date: 2009-10-07
Filing date: 2010-10-06
Publication date: 2011-04-14
Also published as: JPWO2011043357A1

Abstract

Disclosed are an irradiation method of a laser, a frequency adjustment method of a piezoelectric vibrator using the same, and a frequency-adjusted piezoelectric device using the same capable of minimizing damage to silicon material or surrounding constituent elements, while the laser is transmitted through the silicon material and is irradiated preferably onto an object ahead of the same. Accordingly, as a laser to be used, a so-called "femtosecond laser" which is a pulse laser of a pulse width of 50 to 1000 fs (femtoseconds) is selected. This technology can, for example, preferably be used when irradiating a laser onto a piezoelectric vibrator contained in the interior of an electronic component package comprising silicon material to adjust the resonance frequency thereof.

Description

Laser irradiation method, frequency adjustment method of piezoelectric vibrator using the same, and piezoelectric device frequency adjusted using the same

The present invention relates to a laser irradiation method, a frequency adjustment method of a piezoelectric vibrator using the same, and a piezoelectric device frequency-adjusted using the method.

Lasers are widely used in the field of electronic component manufacturing, and in particular in the field of semiconductor electronic component manufacturing, it is known that a laser beam is transmitted through a silicon material to irradiate a target object. (For example, see Patent Documents 1 and 2)

FIG. 12 is a cross-sectional view schematically showing a part of the semiconductor electronic component manufacturing process. First, the semiconductor electronic component shown here is an electronic component package formed by bonding a flat lid member (lid) 2 made of silicon material to a box-shaped substrate (package substrate) 1 made of silicon material. This is a so-called package type piezoelectric device in which a plate-like piezoelectric vibrator 3 is hermetically sealed. In this piezoelectric device, an excitation electrode (not shown) formed on the surface of the piezoelectric vibrator 3 is connected to an external connection provided on the outer surface of the package substrate 3 via a through wiring 4 provided on the bottom of the package substrate 1. It is electrically connected to the terminal 5, and electrical signals are input / output through the external connection terminal 5.

In manufacturing the piezoelectric device as described above, the resonance frequency of the piezoelectric vibrator 3 is adjusted as part of the manufacturing process. Resonance frequency (hereinafter simply referred to as frequency) may be adjusted to the higher frequency side or to the lower frequency side, but mainly when adjusting the frequency to the higher frequency side. A laser is used as one of the means.

In the case of adjusting the frequency using a laser, for example, as shown in FIG. 12, the lid member 2 forming a part of the exterior of the piezoelectric device is irradiated with a laser L having a wavelength of about 1300 nm and transmitted. A portion (vibration unit) that contributes to excitation drive of the piezoelectric vibrator 3 by irradiating the laser L that has been formed on a surface of the piezoelectric vibrator 3 in advance to a mass film (metal film or the like) 6 for frequency adjustment that is removed in stages. ), The frequency is changed to the high frequency side.

As described above, the frequency adjustment using the laser is performed at an arbitrary stage of the manufacturing process, and can be selected before and after the lid member 2 is joined to the package substrate 1 in large steps. What is performed after the lid member 2 is bonded to the substrate 1 is that the frequency can be adjusted in a state closer to the final product. Therefore, the frequency is adjusted again in the manufacturing process after the frequency is adjusted once until the final product is obtained. The effect of changing (frequency shift) can be suppressed, and there is an advantage that foreign matter such as dust can be prevented from entering the electronic component package during frequency adjustment. In many cases, it is more preferable in terms of the manufacturing process than before the lid member 2 is bonded to the first member.

The purpose of transmitting a laser beam to a silicon material is not limited to the example described above, but various. In any case, in the field of electronic component manufacturing, it is often required to transmit a laser beam to a silicon material.

When transmitting a laser through a silicon material, it is necessary to use a laser that transmits at least the silicon material. Depending on the values of various parameters (wavelength, pulse width, intensity, focal length, etc.) that determine the properties of the laser In addition to excessive damage to the silicon material and its surrounding components due to the thermal shock of the laser, the silicon material and its surrounding components may be damaged or altered, and the fragments generated by the damage may scatter and adversely affect the surrounding components. .

FIG. 13 is a diagram schematically showing the mechanism of damage caused by laser. As shown here, when the nature of the laser used is not suitable for transmitting the silicon material, the silicon material and its surface Excessive thermal shock is applied to the deposit, and further to the irradiation object itself, and there is a possibility that a portion that should not be processed is processed or deteriorated. Therefore, it is desirable to optimize various parameters that determine the properties of the laser when transmitting the laser through the silicon material.

JP 7-37911 A Special table 2007-512739

The present invention has been made in view of the above problems, and is suitable for a target object by transmitting a laser beam to a silicon material while minimizing damage to the silicon material and its surrounding components. It is an object of the present invention to provide a laser irradiation method capable of irradiating a laser beam, a frequency adjustment method of a piezoelectric vibrator using the same, and a piezoelectric device frequency-adjusted using the method.

In order to achieve the above object, according to the first aspect of the present invention, there is provided a laser that irradiates a silicon material with a laser and transmits the laser, and irradiates the transmitted object to a target object separated from the silicon material. The laser is a pulse laser having a pulse width of 50 to 1000 fs.

The wavelength of the laser can be a laser irradiation method of 1200 to 4000 nm.

According to the second aspect of the present invention, the resonance frequency of the piezoelectric vibrator is adjusted by irradiating the piezoelectric vibrator housed in the electronic component package at least partially made of a silicon material with a laser. A method of adjusting a frequency of a piezoelectric vibrator, wherein the pulsed laser in any one of the above laser irradiation methods is irradiated as a laser to the silicon material region of the electronic component package and the transmitted laser is transmitted through the piezoelectric vibration. The frequency of the piezoelectric vibrator is adjusted by irradiating the child.

The resonance frequency of the piezoelectric vibrator may be adjusted by removing the mass film formed on the surface of the piezoelectric vibrator with the laser.

The resonance frequency of the piezoelectric vibrator may be adjusted by removing the base material of the piezoelectric vibrator with the laser.

According to the third aspect of the present invention, the resonance frequency of the piezoelectric vibrator is adjusted by irradiating the piezoelectric vibrator housed in the electronic component package, at least part of which is made of a silicon material, with a laser. A method of adjusting a frequency of a piezoelectric vibrator, the pulse laser in any of the laser irradiation methods as the laser is irradiated to and transmitted through a silicon region of the electronic component package, and the transmitted laser is transmitted to the electronic component package The mass film formed on the inner surface is irradiated to scatter the mass film, and the scattered mass film is attached to the piezoelectric vibrator to adjust the resonance frequency of the piezoelectric vibrator.

According to a fourth aspect of the present invention, there is provided a piezoelectric device in which a piezoelectric vibrator is housed in an electronic component package at least partially made of a silicon material, and the frequency of any of the above piezoelectric vibrators The frequency is adjusted using the adjustment method.

According to the present invention, when the laser is transmitted through the silicon material, the parameters that determine the properties of the laser are optimized, so that damage to the silicon material is minimized and the object separated from the silicon material is separated. A laser can be suitably irradiated. Further, if this technique is used when adjusting the frequency of the piezoelectric vibrator, it is possible to suitably adjust the frequency while minimizing damage to the electronic component package that accommodates the piezoelectric vibrator.
The objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings.

FIG. 1 is a diagram showing the principle of a laser irradiation method according to the present invention. FIG. 2 is a graph showing the relationship between the laser wavelength and transmittance for a silicon single crystal. FIG. 3 is a diagram showing an example of a laser irradiation apparatus used for carrying out the laser irradiation method according to the present invention. FIG. 4 is a diagram showing a basic experiment method for evaluating the effectiveness of the laser irradiation method according to the present invention. 5A and 5B are plan views of an evaluation sample that has undergone the basic experiment shown in FIG. 4. FIG. 5A shows a state in which the surface of the upper silicon substrate is viewed from the laser irradiation side, and FIG. The surface of the thin film is viewed from the laser irradiation side. FIG. 6 is a diagram showing a basic experiment using a conventional laser irradiation method as a comparative example to the laser irradiation method according to the present invention. 7A and 7B are plan views of an evaluation sample that has undergone the basic experiment shown in FIG. 6. FIG. 7A shows the state of the surface of the silicon substrate viewed from the laser irradiation side, and FIG. The surface is seen from the side opposite to the laser irradiation side. FIG. 8 is a diagram illustrating a frequency adjustment method (first embodiment) of a piezoelectric vibrator according to the present invention. FIG. 9 is a diagram illustrating a frequency adjustment method (Example 2) of a piezoelectric vibrator according to the present invention. 10A and 10B are images observed by a laser microscope of an evaluation sample subjected to frequency adjustment using the frequency adjustment method of the piezoelectric vibrator shown in FIG. 9, and FIG. 10A shows the surface of the piezoelectric vibrator on the laser irradiation side. 10B shows a state in which the lid member through which the laser is transmitted is viewed from the side opposite to the laser irradiation side. 11A to 11D are SEM observation images of an evaluation sample subjected to frequency adjustment using the frequency adjustment method of the piezoelectric vibrator shown in FIG. 9, and FIG. 11A shows the surface of the piezoelectric vibrator from the laser irradiation side. FIG. 11B shows an enlarged view of a part of FIG. 11A (around the end of scanning 1), and FIG. 11C shows a part of FIG. 11A (around the start of scanning 2). 11D shows a state seen from an enlarged view, and FIG. 11D shows a state seen from an enlarged portion of FIG. FIG. 12 is a cross-sectional view schematically showing a part of the manufacturing process of the semiconductor electronic component. FIG. 13 is a diagram schematically showing a mechanism of occurrence of damage by a laser.

The laser irradiation method according to the present invention is characterized by setting a pulse width of 50 to 1000 fs (femtoseconds), which is one of the parameters that determine the properties of the laser used when transmitting the laser through the silicon material. .

Such a short-pulse-width laser is commonly called a femtosecond laser, and the photon absorption range is limited to a range of μm order because the irradiation time of the laser is extremely short. It is characterized by a narrower range of thermal shock than lasers, less damage to the irradiated object, and non-linear optical effects due to steep rising pulses, so it is usually difficult to absorb lasers and reflective materials. The laser energy can be efficiently transmitted even to a material having a high rate, and the micro area can be selectively processed by focusing the micro area on the micro area.

The present applicant has found that by irradiating a silicon material with a femtosecond laser having such characteristics, it is possible to transmit the silicon material while minimizing damage to the silicon material. The idea was to use a laser beam through a silicon material and irradiate the object ahead of it.

FIG. 1 is a diagram showing in principle the laser irradiation method according to the present invention, and FIG. 2 is a graph showing the relationship between the wavelength and transmittance of a laser with respect to a silicon material. In carrying out the laser irradiation method according to the present invention, first, the wavelength of the femtosecond laser to be used must be at least transmitted through the silicon material. As the wavelength, for example, about 900 nm as shown in FIG. As described above, a wavelength band of about 1200 nm or more in which the transmittance is about 50% or more is more preferable.

Here, it is considered to use a laser having a wavelength band of 1200 to 4000 nm, which has a particularly high transmittance. First, as shown in FIG. 1, from a laser light source capable of outputting a femtosecond laser, visible light is generally used. A laser having a wavelength of 780 nm as an area is output, and the wavelength is converted to 1200 to 4000 nm by passing it through a wavelength conversion element (OPO: Optical Parametric Oscillator). Then, the wavelength-converted laser is condensed by a condensing optical system such as a lens and then irradiated onto the irradiation object.

Here, if the focus of the laser is adjusted to an arbitrary point on the irradiation object and a silicon material is placed between the focus and the condensing optical system, the laser that has passed through the condensing optical system will damage the silicon material significantly. Without being given, it passes through the silicon material and irradiates the irradiation object ahead.

FIG. 3 is a diagram showing an example of a laser irradiation apparatus used for carrying out the laser irradiation method according to the present invention. The laser irradiation apparatus shown here is configured based on the principle of the laser irradiation method according to the present invention shown in FIG. 1, and a laser light source 11 that outputs a femtosecond laser having a wavelength in the visible light region (for example, 780 nm). Then, the wavelength conversion element 12 that converts the wavelength of the laser output from the laser light source 11 into a wavelength in the near-infrared region (for example, 1200 to 4000 nm), and the laser that has been wavelength-converted by the wavelength conversion element 12 are condensed. A condensing optical system 13 such as a lens, a triaxial direction (XYZ directions) orthogonal to each other, a movable table 14 movable around each axis, a vacuum chamber 15 for storing the movable table 14 in a vacuum atmosphere, And an N ₂ chamber 16 for storing components other than the laser light source 11 in a nitrogen atmosphere (N ₂ purge).

The movable table 14 is provided with a holding mechanism that holds the laser irradiation object 17 in a predetermined posture, so that the movable table 14 appropriately moves in the XYZ directions and the rotation directions around those axes while holding the irradiation object 17. Thus, the position of the irradiation object 17 with respect to the laser can be arbitrarily changed.

The N ₂ chamber 16 is mainly for preventing the laser from being attenuated. Since the laser converted into a wavelength of 1200 to 4000 nm by the wavelength conversion element 12 is significantly absorbed in moisture, it is in the optical path of the laser. It is filled with nitrogen, which is an inert gas, to eliminate moisture in the air.

The vacuum chamber 15 is for performing laser irradiation on the irradiation object 17 in a vacuum atmosphere, and an arbitrary degree of vacuum can be created by a vacuum exhaust means such as a vacuum pump 18. The vacuum chamber 15 is necessary only when it is necessary to perform laser irradiation on the irradiation object 17 in a vacuum atmosphere due to the nature of the irradiation object 17, and may be omitted as appropriate depending on the situation. it can.

FIG. 4 is a diagram showing a basic experiment for evaluating the effectiveness of the laser irradiation method according to the present invention. As a basic experiment, a single-crystal silicon substrate 23 having no deposit on the surface thereof is opposed to the Au thin film 21 on the silicon single crystal substrate 22 on which the Au thin film 21 is formed on one side (upper surface in the drawing) of the main surface. In this manner, the sample bonded through the spacer 24 is used as an evaluation sample, and the evaluation sample is slightly tilted with respect to the sample mounting surface, and the lower silicon single crystal from the upper silicon single crystal substrate 23 side. The Au thin film 21 of the substrate 22 was focused and irradiated with the femtosecond laser L, and at the same time, it was scanned linearly in a certain direction without changing the focal length.

In the above basic experiment, when the laser L is scanned as the direction from the lower side to the higher side of the evaluation sample inclined in the scanning direction of the laser L (arrow direction in the figure), the evaluation sample is inclined. As the irradiation position moves, the Au thin film 21 is processed while the focal position of the laser L moves relatively and continuously toward the lower silicon single crystal substrate 22. In this experimental method, a change in the processing state of the Au thin film 21 in accordance with a change in the focal position of the laser L can be observed simultaneously.

The specifications of the basic experiment are as follows.
Laser type: Fiber laser wavelength: 1552.5nm
Pulse width: 800 fs
Output intensity: 5 μJ / pulse (average intensity 2.5 W, maximum intensity 0.8 MW or more)
Repetition frequency: 100 kHz
Beam diameter: 5 mm x 5 mm (during emission)
Laser scanning speed: 1 mm / s
Evaluation sample tilt angle: 0.96 °

The specifications of the evaluation sample are as follows.
Outline of silicon single crystal substrate: 20 mm square silicon single crystal substrate thickness: 350 μm
Gold (Au) thin film thickness: 200 mm (200 angstroms)
Gap between silicon single crystal substrates: 64 μm

5A and 5B are plan views of an evaluation sample that has undergone the basic experiment shown in FIG. 4. FIG. 5A shows the surface of the upper silicon single crystal substrate viewed from the laser irradiation side, and FIG. 5B shows the Au thin film. The surface is seen from the laser irradiation side. First, referring to FIG. 5A, two linear irradiation marks can be seen on the surface of the silicon single crystal substrate 23 (irradiation marks A and B), and the lower irradiation mark B in the figure directly focuses the laser beam. Focusing on this irradiation mark B, the surface layer of the silicon single crystal substrate 23 is physically removed along the laser irradiation region as a result of analysis. The silicon single crystal substrate 23 was not significantly damaged. Although not shown, no particularly large irradiation marks were found on the surface of the silicon single crystal substrate 23 opposite to the laser irradiation side.

Incidentally, the upper irradiation mark A in the drawing is considered to be a secondary irradiation mark formed by reflecting a part of the laser inside the silicon single crystal substrate 23 and focusing in the vicinity of the surface layer. This indicates that regions different from the actual focus of the laser are also processed. This also means that silicon materials are processed for the first time by focusing a short-pulse-width laser to produce a nonlinear optical effect, and conversely, a laser with a wavelength that passes through the silicon material. Even so, it means that the silicon material has no influence unless it is condensed to produce a nonlinear optical effect. That is, focusing on that point and reviewing the physical numerical conditions (parameters) of the laser, it is possible to process the target object by passing the laser through the silicon material without damaging the silicon material. I understand that.

5B, three linear irradiation marks can be seen on the surface of the Au thin film 21 (irradiation marks C, D, E), and the laser output intensity is 5 μJ, 2. The irradiation traces in the case of 5 μJ and 1 μJ are shown. In particular, when attention is paid to the irradiation trace E corresponding to 5 μJ set in this basic experiment, the Au thin film 21 is physically removed along the laser irradiation area. As a result, the lower silicon single crystal 22 is exposed, and it can be seen that the Au thin film 21 is processed by the laser that has passed through the upper silicon single crystal 23.

That is, the above results show that no large laser irradiation traces are formed on the surface of the silicon single crystal substrate 23 located immediately above the processing region of the Au thin film 21 on either the laser incident side or the opposite side. This shows that the object (Au thin film 21) can be processed with a laser through the silicon material without damaging the silicon material.

FIG. 6 is a diagram showing a basic experiment using a laser irradiation method according to the prior art as a comparative example to the laser irradiation method according to the present invention. As a basic experiment, as shown in the drawing, a silicon single crystal substrate 32 having an Au thin film 31 formed on one side of the main surface (lower surface in the drawing) is used as an evaluation sample, and the side on which the Au thin film 31 is formed with respect to the evaluation sample. The Au thin film 31 was focused from the opposite side to the high-power laser L having a longer pulse width than the femtosecond laser.

The specifications of the basic experiment are as follows.
Laser type: Holmium YAG laser wavelength: 2080 nm
Pulse width: 250 μs (half value 150 μs)
Output intensity: 2J / pulse (10W)
Number of irradiations: 2 pulse beam diameter: 200-300 μm
F value of objective lens: f = 20

The specifications of the evaluation sample are as follows.
Outline of silicon single crystal substrate: 30 mm square silicon single crystal substrate thickness: 370 μm (surface is mirror finished)
Au thin film thickness: 0.1 μm (sputter deposition)

7A and 7B are plan views of an evaluation sample that has undergone the basic experiment shown in FIG. 6. FIG. 7A shows the surface of the silicon single crystal substrate as viewed from the laser irradiation side, and FIG. 7B shows the surface of the Au thin film. The state seen from the side opposite to the laser irradiation side is shown. Referring to FIG. 7A, an irradiation mark is seen in the entire laser irradiation region on the surface of the silicon single crystal substrate 32, and a recess R formed by laser thermal shock can be confirmed particularly near the focal point. It turns out that there is a big damage in 32.

7B, a part of the Au thin film 31 is physically removed to expose the lower silicon single crystal substrate 32, and the Au thin film 31 is processed by a laser transmitted through the silicon single crystal substrate 32. However, the contour of the machining area is irregularly disordered, and machining residues (residues) are also seen, so it cannot be said that the machining accuracy is high.

Since the specifications of the basic experiment and the specifications of the evaluation sample do not completely match each other, the basic experiment result of the comparative example and the basic experiment result using the laser irradiation method of the present invention shown in FIG. Although it cannot be compared, it can be sufficiently confirmed that the use of the laser irradiation method according to the present invention can process the Au thin film on the surface of the silicon material while minimizing damage to the silicon material substrate.

FIG. 8 is a diagram showing a frequency adjustment method for a piezoelectric vibrator according to the present invention. The application of the laser irradiation method according to the present invention described above can be arbitrarily selected, and one of them is to use it when adjusting the resonance frequency of the piezoelectric vibrator.

First, in the frequency adjustment method of the piezoelectric vibrator shown here, for a package-type piezoelectric device in which the piezoelectric vibrator 3 is hermetically sealed inside an electronic component package made of a silicon material as shown in FIG. It shall be irradiated with a laser.

Here, an Au thin film 41 is formed as a mass film for frequency adjustment on the surface (the lower surface in the figure) of the lid member 2 facing the inside of the electronic component package at a position substantially opposite to the vibrating portion of the piezoelectric vibrator 3. ing.

When the frequency of the piezoelectric vibrator 3 is adjusted with respect to the above piezoelectric device, the frequency of the piezoelectric vibrator 3 is set to a higher frequency side than the target value in the manufacturing stage in advance, and then formed on the surface of the lid member 2. The femtosecond laser L is irradiated from the lid member 2 side so as to focus on the Au thin film 41, and at the same time, the locus of the laser L linearly scans in a certain direction so as to straddle the formation region of the Au thin film 41. To do.

The irradiated laser passes through the lid member 2 and is irradiated to the opposite Au thin film 41, and the Au thin film 41 is scattered by the thermal shock and adheres to the surface of the piezoelectric vibrator 3.

When the scattering particles of the Au thin film 41 adhere to the surface of the piezoelectric vibrator 3, the substantial mass of the vibrating portion of the piezoelectric vibrator 3 increases and the frequency of the piezoelectric vibrator 3 changes to the low frequency side. Here, if the correlation between the laser irradiation time and the amount of change in the frequency is grasped in advance, the frequency of the piezoelectric vibrator 3 can be adjusted to a desired value by controlling the laser irradiation time. .

In the above frequency adjustment method, since the femtosecond laser is used for the laser, the lid member 2 is not excessively damaged by the laser, and the lid member 2 is broken and a leak occurs between the inside and the outside. There is no such thing.

Further, the laser beam that has passed through the lid member 2 causes secondary scattering of the particles of the Au thin film 41 adhering to the surface of the piezoelectric vibrator 3 (secondary sputtering), and damage to the piezoelectric vibrator 3 itself. The frequency adjustment is performed stably without being affected.

In the above embodiment, the case where the frequency adjusting mass film is formed on the surface of the lid member 2 has been described. However, the mass film can be scattered and attached to the surface of the piezoelectric vibrator 3. If present, the mass film may be formed in any region of the inner surface of the piezoelectric device. For example, the mass film may be formed on the inner surface of the package substrate 1.

FIG. 9 is a diagram showing a frequency adjustment method for a piezoelectric vibrator according to the present invention. In Example 1 shown in FIG. 8, the frequency of the piezoelectric vibrator 3 is adjusted from the high frequency side to the low frequency side. However, in the frequency adjusting method of the piezoelectric vibrator shown in FIG. Is adjusted from the low frequency side to the high frequency side.

First, as a structural feature of the second embodiment, a mass film for frequency adjustment is formed on the surface of the lid member 2 in the first embodiment, whereas a mass is formed on the surface of the lid member 2 in the second embodiment. Instead of forming a film, a mass film for frequency adjustment (Au thin film 42) is formed on the surface of the piezoelectric vibrator 3 instead. In particular, here, it is assumed that the mass film is formed only on the main surface (upper surface in the drawing) of the main surface of the piezoelectric vibrator 3 on the side facing the lid member 2.

When the frequency of the piezoelectric vibrator 3 is adjusted, the Au thin film 42 formed on the surface of the piezoelectric vibrator 3 is set in advance in the manufacturing stage after setting the frequency of the piezoelectric vibrator 3 to be lower than the target value. The femtosecond laser L is irradiated from the lid member 2 side so as to be focused on, and at the same time, the locus of the laser L linearly scans in a certain direction so as to straddle the formation region of the Au thin film 43.

The irradiated laser is transmitted through the lid member 2 and irradiated onto the Au thin film 43 on the surface of the piezoelectric vibrator 3, and the Au thin film 43 is scattered and physically removed by the thermal shock.

When the Au thin film 43 scatters from the surface of the piezoelectric vibrator 3, the substantial mass of the vibration part of the piezoelectric vibrator 3 decreases, and the frequency of the piezoelectric vibrator 3 changes to the high frequency side.

Here, as in the first embodiment, if the correlation between the laser irradiation time and the amount of change in frequency is grasped in advance, the frequency of the piezoelectric vibrator 3 is controlled to a desired value by controlling the laser irradiation time. And can be adjusted.

10A and 10B are images observed by a laser microscope of an evaluation sample subjected to frequency adjustment using the frequency adjustment method of the piezoelectric vibrator shown in FIG. 9, and FIG. 10A shows the surface of the piezoelectric vibrator on the laser irradiation side. FIG. 10B shows a state where the lid member through which the laser is transmitted is viewed from the side opposite to the laser irradiation side. In order to evaluate the effectiveness of the frequency adjustment method of the piezoelectric vibrator shown in FIG. 9, the applicant of the present application conducted a basic experiment using an evaluation sample. As a basic experiment, a package-type piezoelectric device in which a piezoelectric vibrator 3 having a tuning-fork-type vibrating portion is hermetically sealed inside an electronic component package made of a silicon material as shown in FIG. 12 is used as an evaluation sample. The laser was transmitted through the lid member 2 to irradiate the surface of the vibrating portion of the piezoelectric vibrator 3 and simultaneously the laser was sequentially scanned in three directions in the direction indicated by the arrows in FIG. 10A. In the first scan (scan 1) and the second scan (scan 2), a laser is irradiated to the frequency adjusting mass film (Au thin film) formed on the surface of the vibrating portion, and the third scan (scan 3). Then, the base material (quartz crystal) of the vibration part was directly irradiated with a laser, thereby obtaining frequency change amounts of 26.4 ppm, 56.8 ppm, and 21.6 ppm, respectively. 10A shows only one end of the tuning-fork type vibration part, and FIG. 10B shows the surface of the lid member facing the one end of the vibration part shown in FIG. 10A.

The specifications of the laser are as follows.
Wavelength: 1552.5nm
Pulse width: 800 fs
Maximum strength: 0.8 MW or more

Referring to FIG. 10A, it can be confirmed that laser irradiation traces are formed on the surface of the vibrating part by each scanning of the laser (scanning 1 to 3). Referring to FIG. 10B, the surface of the lid member through which the laser is transmitted. Although the Au thin film and the crystal particles which are thought to have been scattered by the laser irradiation are attached, it can be confirmed that there is no significant damage such as a crack in the lid member.

11A to 11D are SEM observation images of an evaluation sample subjected to frequency adjustment using the frequency adjustment method of the piezoelectric vibrator shown in FIG. 9, and FIG. 11A shows the surface of the piezoelectric vibrator from the laser irradiation side. 11B is an enlarged view of a part of FIG. 11A (around the end of the scanning 1 end), FIG. 11C is an enlarged view of a part of FIG. 11A (around the starting end of the scanning 2), FIG. 11D shows a state in which a part of FIG. 11A (the vicinity of the end portion of the scanning 3) is enlarged. Referring to FIG. 11B, it can be confirmed that only the Au thin film has been removed in scan 1, and with reference to FIG. 11C, it can be confirmed that a part of the lower-layer crystal has been removed together with the Au thin film. Referring to 11D, it can be confirmed that in scanning 3, only the quartz crystal is removed to a certain depth. From the above results, it can be understood that the frequency of the piezoelectric vibrator hermetically sealed in the electronic component package made of silicon can be adjusted by the femtosecond laser transmitted through the electronic component package.

As described above, even if the mass film for frequency adjustment is formed on the surface of the piezoelectric vibrator 3, the lid member 2 and the piezoelectric vibrator 3 are excessively damaged by the laser similarly to the first embodiment. The frequency adjustment is performed stably.

In the above embodiment, the case where the mass film for frequency adjustment is formed on the upper surface of the piezoelectric vibrator 3 has been described. However, if the mass film for frequency adjustment can be scattered and removed. Alternatively, it may be formed on the other surface (lower surface or side surface) of the piezoelectric vibrator 3.

In the above embodiment, the mass film previously formed on the surface of the piezoelectric vibrator 3 is removed by the laser to reduce the mass of the piezoelectric vibrator. However, the piezoelectric vibrating piece which is a base material of the piezoelectric vibrator 3 is removed. You may make it reduce the mass of the piezoelectric vibrator 3 by removing a part of itself with a laser.

In the first and second embodiments, various piezoelectric vibrators such as a so-called tuning fork-type piezoelectric vibrator having a tuning-fork type vibrating portion and a so-called AT-cut piezoelectric vibrator having a rectangular shape in plan view can be used. However, it is not limited to them.

Further, the mass film for adjusting the frequency is not limited to Au, and various other materials can be appropriately selected.

In addition, the pulse width of the laser used in the laser irradiation method of the present invention is not strictly limited to the numerical range defined in the present specification. As long as there is a critical point in the numerical range, some error can be allowed without departing from the spirit of the present invention.

In addition, the silicon material to be laser-transmitted in the present invention is not limited to the silicon single crystal shown in the embodiment, and covers all materials mainly composed of silicon (Si) without departing from the gist of the present invention. Become.

This application is based on Japanese Patent Application No. 2009-233301, filed by the applicant in Japan on October 7, 2009, the entire contents of which are incorporated into this application by reference. Further, the entire contents of JP-A-7-37911 and JP-T-2007-512739 cited as the background art of the present invention are incorporated into the present application by reference.

The above description of specific embodiments of the present invention has been presented for purposes of illustration. They are not intended to be exhaustive or to limit the invention to the precise form described. It will be apparent to those skilled in the art that many modifications and variations are possible in light of the above description.

The laser irradiation method according to the present invention can be applied to any application that requires transmission of a laser through a silicon material without departing from the spirit of the present invention. Examples include, but are not limited to, cutting, modification, and melting of an object.

1 Package substrate 2 Lid member
DESCRIPTION OF SYMBOLS 3 Piezoelectric vibrator 4 Through wiring 5 External connection terminal 6 Mass film | membrane 11 Laser light source 12 Wavelength conversion element 13 Condensing optical system 14 Movable table 15 Vacuum chamber 16 N ₂ chamber 17 Irradiation target 18 Vacuum pump 21 Au thin film 22 Silicon single crystal Substrate 23 Silicon single crystal substrate 24 Spacer 31 Au thin film 32 Silicon single crystal substrate 41 Mass film (Au thin film)
42 Mass film (Au thin film)

Claims

Irradiating a silicon material with a pulse laser having a pulse width of 50 to 1000 fs to transmit the silicon material;
Irradiating the laser beam that has passed through a target object that is separated from the silicon material.
2. The laser irradiation method according to claim 1, wherein a wavelength of the laser is 1200 to 4000 nm.
A method of adjusting a frequency of a piezoelectric vibrator, wherein a resonance frequency of the piezoelectric vibrator is adjusted by irradiating a laser on a piezoelectric vibrator housed in an electronic component package at least part of which is made of a silicon material,
Irradiating and transmitting the pulse laser according to claim 1 or 2 to the silicon material region of the electronic component package as the laser;
Irradiating the transmitted laser to the piezoelectric vibrator to adjust the resonance frequency of the piezoelectric vibrator.
The adjusting the resonance frequency of the piezoelectric vibrator includes adjusting a resonance frequency of the piezoelectric vibrator by removing a mass film formed on a surface of the piezoelectric vibrator with the laser. The method for adjusting the frequency of the piezoelectric vibrator according to claim 1.
The piezoelectric vibration according to claim 3, wherein adjusting a resonance frequency of the piezoelectric vibrator includes adjusting a resonance frequency of the piezoelectric vibrator by removing a base material of the piezoelectric vibrator with the laser. Child frequency adjustment method.
A method of adjusting a frequency of a piezoelectric vibrator, wherein a resonance frequency of the piezoelectric vibrator is adjusted by irradiating a laser on a piezoelectric vibrator housed in an electronic component package at least part of which is made of a silicon material,
Irradiating and transmitting the pulse laser according to claim 1 or 2 to the silicon material region of the electronic component package as the laser;
Irradiating the mass film formed on the inner surface of the electronic component package with the transmitted laser to scatter the mass film;
Adjusting the resonance frequency of the piezoelectric vibrator by attaching the scattered mass film to the piezoelectric vibrator.
An electronic component package at least partially composed of a silicon material;
A piezoelectric vibrator housed inside the electronic component package,
A piezoelectric device in which the resonance frequency of the piezoelectric vibrator is adjusted using the frequency adjustment method for a piezoelectric vibrator according to any one of claims 3 to 6.