Transducer, resonator, oscillator, and method for manufacturing the same

Abstract

To easily manufacture a transducer having a vibrator with a resonant frequency having a target temperature characteristic using a semiconductor manufacturing technology.SOLUTION: A transducer 10 includes a single crystal silicon 11 and a silicon oxide film 12. The single crystal silicon 11 has an anchor region 17 and a vibrating body 13 supported by the anchor region 17. The silicon oxide film 12 is formed on the surface of the single crystal silicon 11. The silicon oxide film 12 has a silicon portion 14 reduced from silicon oxide.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to transducers, resonators, oscillators, and methods of manufacturing transducers. [Background technology]

[0002] Vibrators that utilize semiconductor manufacturing technology are manufactured using silicon with an oxidized surface. The resonant frequency of this vibrator has temperature characteristics that are determined by the temperature characteristics of silicon and silicon oxide. By manufacturing the vibrator using an appropriate combination of silicon and silicon oxide, it is possible to achieve the target temperature characteristics for the resonant frequency of the vibrator.

[0003] [overview] If variations occur in the quality of the silicon oxide produced in the process of oxidizing the silicon surface, it becomes difficult to consistently manufacture a vibrating body having a resonant frequency with the target temperature characteristics.

[0004] An object of the present disclosure is to provide a transducer, a resonator, an oscillator, and a method for manufacturing a transducer that can easily manufacture a vibrating body having a resonant frequency with a target temperature characteristic using semiconductor manufacturing technology.

[0005] In order to solve the above-mentioned problems, one aspect of the present disclosure provides a transducer including single-crystal silicon and a silicon oxide film. The single-crystal silicon has an anchor region and a vibrating body supported by the anchor region. The silicon oxide film is formed on a surface of the single-crystal silicon. The silicon oxide film includes a silicon portion reduced from the silicon oxide. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of an actuator according to an embodiment. [Figure 2] FIG. 2 is a diagram showing another example of the configuration of the actuator according to the embodiment. [Figure 3]FIG. 3 is a diagram showing the frequency temperature coefficients of single crystal silicon and silicon oxide used in the vibrating bodies of the actuators of FIGS. [Figure 4] FIG. 4 is a flowchart showing an example of a procedure for a method for manufacturing an actuator according to this embodiment. [Figure 5] FIG. 5 is a diagram showing an example of a resonance mode specific to the vibrating body. [Figure 6] FIG. 6 is a diagram showing another example of a resonance mode specific to the vibrating body. [Figure 7] FIG. 7 is a diagram showing still another example of a resonance mode specific to the vibrating body. [Figure 8] FIG. 8 is a diagram illustrating an example of an oscillator according to the embodiment.

[0007] [Detailed explanation] Hereinafter, semiconductor devices according to several embodiments will be described in detail with reference to the drawings. However, it should be noted that the drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each part, etc. may differ from the actual ones. Furthermore, it goes without saying that the drawings may include parts with different dimensional relationships or ratios.

[0008] The embodiments described below are comprehensive or specific examples. The numerical values, shapes, materials, components, installation positions, and connection forms of the components shown in the following embodiments are merely examples and are not intended to limit the scope of the present disclosure. Furthermore, among the components in the following embodiments, components that are not recited in the independent claims that represent the highest concepts are described as optional components. Furthermore, the dimensional proportions in the drawings are exaggerated for the sake of explanation and may differ from the actual proportions. Furthermore, the following embodiments and their variations may include similar components, and the same reference numerals will be used to denote similar components, and redundant explanations will be omitted.

[0009] An example of the configuration of an actuator as a transducer according to an embodiment will be described with reference to Figures 1 and 2. The actuator according to the embodiment is manufactured as a MEMS (Micro Electro Mechanical System).

[0010] The actuator 10 of the example shown in FIG. 1 includes single crystal silicon 11 and a silicon oxide film 12. The silicon oxide film 12 is formed by thermal oxidation on the surface of the single crystal silicon 11, which is the main surface, i.e., the upper surface in the figure. The method for forming the silicon oxide film 12 on the surface of the single crystal silicon 11 is not limited to thermal oxidation. For example, the silicon oxide film 12 may be formed on the surface of the single crystal silicon 11 by a CVD (Chemical Vapor Deposition) method, a sputtering method, or the like. The actuator 10 has a vibrating body 13 with a cantilever structure formed by etching the single crystal silicon 11 after the silicon oxide film 12 has been formed. The silicon oxide film 12 has a silicon portion 14 reduced from silicon oxide.

[0011] The actuator 20 in the example shown in FIG. 2 includes single-crystal silicon 21 and a silicon oxide film 22. The actuator 20 has a vibrating body 23 with a cantilever structure formed by etching the single-crystal silicon 21. The silicon oxide film 22 is formed on the upper surface in the figure, which is the main surface of the single-crystal silicon 21, and on the lower and both side surfaces in the horizontal direction in the figure, which are surfaces other than the main surface of the vibrating body 23. The silicon oxide film 22 on the upper surface of the single-crystal silicon 21 may be formed before or after the formation of the vibrating body 23. The silicon oxide film 22 can be formed on the surface of the single-crystal silicon 21 by thermal oxidation treatment, CVD, sputtering, or the like. The silicon oxide film 22 on both sides of the vibrating body 23 has silicon portions 24 reduced from silicon oxide. FIG. 2 shows only the silicon portions 24 provided on the lateral silicon oxide film 22 on the front side of the figure.

[0012] The vibrating bodies 13, 23 in FIGS. 1 and 2 have first ends 15, 25 and second ends 16, 26. The first ends 15, 25 of the vibrating bodies 13, 23 are fixed to anchor regions 17, 27 remaining in the single-crystal silicon 11, 21 after etching. The second ends 16, 26 of the vibrating bodies 13, 23 are the tips of the vibrating bodies 13, 23 extending from the anchor regions 17, 27 of the single-crystal silicon 11, 21. Hereinafter, the extension direction of the vibrating bodies 13, 23 will be referred to as extension direction X. The first ends 15, 25 are fixed ends, and the second ends 16, 26 are free ends. The vibrating bodies 13, 23 can vibrate in the vertical direction Z or horizontal direction Y in the drawings. The extension direction X, horizontal direction Y, and vertical direction Z are perpendicular to each other.

[0013] For example, the actuator 10 in Fig. 1 can be configured as a piezoelectric actuator in which the vibrating body 13 vibrates in the vertical direction Z or the horizontal direction Y by forming a metal layer 18 such as an electrode or a piezoelectric film on the upper side of the silicon oxide film 12 of the vibrating body 13 in the figure. For example, the actuator 20 in Fig. 2 can be configured as a capacitance type actuator in which the vibrating body 23 vibrates in the horizontal direction Y by forming metal layers such as electrodes (not shown) on the silicon oxide film 22 on both sides of the vibrating body 23 in the horizontal direction Y.

[0014] The vibrating bodies 13 and 23 of the actuators 10 and 20 in FIGS. 1 and 2 resonate by vibrating at their natural frequencies. For example, when the actuators 10 and 20 are used as resonators, if the resonant frequency, which is the vibration frequency at which the vibrating bodies 13 and 23 resonate, changes with temperature, the frequency of the standing wave generated by the resonator also changes with temperature. For example, when the actuators 10 and 20 are used as oscillators, if the resonant frequency of the vibrating bodies 13 and 23 changes with temperature, the frequency of the clock signal output by the oscillator also changes with temperature. The temperature characteristics of the resonant frequency of the vibrating bodies 13 and 23 are the sum of the temperature characteristics of the resonant frequency of the single crystal silicon 11 and 21 used in the vibrating bodies 13 and 23 and the temperature characteristics of the resonant frequency of the silicon oxide films 12 and 22. The temperature characteristics of the resonant frequency of the single crystal silicon 11 and 21 and the silicon oxide films 12 and 22 can be expressed, for example, by the temperature coefficient of frequency (TCF) of the resonant frequency.

[0015] Figure 3 shows the temperature coefficients of frequency (TCF) of the resonant frequencies of the single crystal silicon 11, 21 and the silicon oxide films 12, 22. The resonant frequencies of the single crystal silicon 11, 21 have a temperature characteristic in which the frequency deviation Δf / f decreases as the temperature increases. The temperature coefficient of frequency TCF1 of the resonant frequencies of the single crystal silicon 11, 21 is negative. The resonant frequencies of the silicon oxide films 12, 22 have a temperature characteristic in which the frequency deviation Δf / f increases as the temperature increases. The temperature coefficient of frequency TCF2 of the resonant frequencies of the silicon oxide films 12, 22 is positive. Because the vibrating bodies 13, 23 are composed of the single crystal silicon 11, 21 and the silicon oxide films 12, 22, if the absolute values ​​of the temperature coefficients of frequency TCF1 and TCF2 are the same, the temperature coefficient of frequency TCF3 of the vibrating bodies 13, 23 will be zero. If the frequency temperature coefficient TCF3 becomes zero, the frequency deviation Δf / f of the resonant frequency of the vibrating bodies 13 and 23 with respect to temperature change becomes constant regardless of temperature, and the resonant frequency of the vibrating bodies 13 and 23 becomes a constant frequency even when the temperature changes.

[0016] When the vibrating bodies 13 and 23 have a metal layer, such as the metal layer 18 in FIG. 1, on the surface of the silicon oxide film 12 and 22, the temperature characteristic of the resonant frequency of the vibrating bodies 13 and 23 is a temperature characteristic that further adds the temperature characteristic of the resonant frequency of the material that makes up the metal layer. When the silicon oxide film 12 and 22 has a metal layer on the surface, the frequency temperature coefficient of the resonant frequency of the material that makes up the metal layer is taken into consideration. In this case, the absolute value of the frequency temperature coefficient TCF2 is calculated so that the absolute value of the frequency temperature coefficient, obtained by adding the frequency temperature coefficient of the resonant frequency of the material that makes up the metal layer, is the same as the absolute value of the frequency temperature coefficient TCF1. If the frequency temperature coefficient TCF2 is set to the calculated absolute value, the frequency deviation Δf / f of the resonant frequency of the vibrating bodies 13 and 23 with respect to temperature change becomes constant regardless of temperature, and the resonant frequency of the vibrating bodies 13 and 23 remains constant even when the temperature changes.

[0017] Even if silicon oxide films 12, 22 are formed on the surfaces of single crystal silicon 11, 21 in a manner calculated to achieve a desired temperature coefficient of frequency (TCF2), variations occur in the actual quality of the silicon oxide films 12, 22. If the quality of the silicon oxide films 12, 22 varies, the resonant frequency of the vibrating bodies 13, 23 cannot be made constant regardless of temperature. Conventionally, single crystal silicon with a silicon oxide film formed in a larger amount than calculated was not used in the manufacture of actuators because it was out of spec. The actuators 10, 20 of the embodiment are manufactured using the manufacturing method described below to ensure that the resonant frequency of the vibrating bodies 13, 23 is constant.

[0018] In the manufacturing method of the embodiment, silicon oxide films 12, 22 are intentionally formed on the surfaces of single crystal silicon 11, 21 in excess of a calculated target amount, and then, as shown in FIGS. 1 and 2 , an electron beam EB is irradiated onto the silicon oxide films 12, 22. The electron beam EB irradiation reduces silicon oxide to form silicon portions 14, 24 at the irradiated locations of the silicon oxide films 12, 22. By forming the silicon portions 14, 24 in the silicon oxide films 12, 22, the absolute value of the temperature coefficient of frequency TCF1 of the single crystal silicon 11, 21 of the vibrating bodies 13, 23 increases, and the absolute value of the temperature coefficient of frequency TCF2 of the silicon oxide films 12, 22 decreases. The electron beam EB irradiation of the silicon oxide films 12, 22 is repeated until the temperature characteristics of the resonant frequency of the vibrating bodies 13, 23 reach the target temperature characteristics where the resonant frequency does not change with temperature.

[0019] FIG. 4 is a flowchart illustrating an example of a procedure for manufacturing the actuators 10 and 20 according to the embodiment. In this manufacturing method, a measurement step (step S11) is first performed to measure the temperature characteristics of the resonant frequency of the oscillators 13 and 23, which have silicon oxide films 12 and 22 intentionally formed on the surfaces of the single-crystal silicon 11 and 21 in excess of a target amount. In the measurement step, a probe (not shown) is connected to the actuators 10 and 20, and the oscillators 13 and 23 are vibrated at, for example, two or more ambient temperatures to measure the resonant frequencies of the oscillators 13 and 23 at each ambient temperature. By measuring the resonant frequencies of the oscillators 13 and 23 at two or more ambient temperatures, the amount of change in the resonant frequency of the oscillators 13 and 23 with respect to changes in ambient temperature can be calculated, and the temperature characteristics of the resonant frequency of the oscillators 13 and 23 can be measured. The measurement step of step S11 may be performed on a wafer before the semiconductor chips constituting the actuators 10 and 20 are singulated, or may be performed after the semiconductor chips are singulated and packaged.

[0020] Next, a determination step is performed to determine whether or not to continue the manufacturing work of the actuators 10, 20 (step S12). In the determination step, it is determined whether or not the temperature characteristics of the resonant frequencies of the vibrating bodies 13, 23 measured in step S11 are the target temperature characteristics described above. If the temperature characteristics measured in step S11 are the target temperature characteristics, the determination result of the determination step is "end" (NO in step S12). If the determination result is "end", the manufacturing work of the actuators 10, 20 is ended. If the temperature characteristics measured in step S11 are not the target temperature characteristics, the determination result of the determination step is "continue" (YES in step S12). If the determination result is "continue", the manufacturing work of the actuators 10, 20 is continued, and the procedure proceeds to step S13 and subsequent steps.

[0021] In step S13, the irradiation conditions of the electron beam EB irradiated onto the silicon oxide films 12 and 22 are set to change the temperature characteristics of the resonant frequency of the vibrating bodies 13 and 23 from the temperature characteristics measured in step S11 to a target temperature characteristic. As shown in FIGS. 1 and 2, silicon oxide is reduced to form silicon portions 14 and 24 in the portions of the silicon oxide films 12 and 22 irradiated with the electron beam EB. As the silicon portions 14 and 24 are formed in the silicon oxide films 12 and 22, the amount of silicon oxide film 12 and 22, which was formed in excess of the target amount on the single-crystal silicon 11 and 21, decreases. Because the amount of silicon oxide in the vibrating bodies 13 and 23 decreases and the amount of silicon increases, the frequency temperature coefficient TCF3 of the vibrating bodies 13 and 23, calculated by adding the frequency temperature coefficients TCF1 and TCF2, approaches the target temperature characteristic. In step S13, the irradiation conditions of the electron beam EB are determined based on the difference between the temperature characteristics of the resonant frequency of the vibrating bodies 13 and 23 measured in step S11 and the target temperature characteristic.

[0022] The beam diameter of the electron beam EB is sufficiently smaller than the size of the silicon oxide films 12 and 22. The size of the silicon portions 14 and 24 formed by irradiating one spot on the silicon oxide films 12 and 22 with the electron beam EB is also sufficiently smaller than the size of the silicon oxide films 12 and 22. When irradiating the silicon oxide films 12, 22 with an electron beam EB to form silicon portions 14, 24 in the silicon oxide films 12, 22, the electron beam EB is irradiated at multiple locations on the silicon oxide films 12, 22 while shifting the irradiation locations as indicated by the dashed arrows. When the vibrating bodies 13, 23 vibrate at their resonant frequency, locations that experience large displacements are subjected to greater stress due to the vibration of the vibrating bodies 13, 23. Irradiating these locations with the electron beam EB reduces silicon oxide to silicon, resulting in a greater change in the temperature coefficient of frequency (TCF3) of the vibrating bodies 13, 23 than when irradiating other locations with the electron beam EB. A greater change in the temperature coefficient of frequency (TCF3) of the vibrating bodies 13, 23 brings the temperature characteristics of the resonant frequency of the vibrating bodies 13, 23 closer to the target temperature characteristics.

[0023] 5 to 7 are diagrams showing vibration modes in resonance modes specific to the vibrating body. The resonance mode in FIG. 6, which is a secondary bending mode, has a higher frequency than the resonance mode in FIG. 5, which is a primary bending mode, and the resonance mode in FIG. 7, which is a tertiary bending mode, has a higher frequency than the resonance mode in FIG. 6. When the vibrating bodies 13 and 23 vibrate in each resonance mode in FIGS. 5 to 7, the portions of the first ends 15 and 25 fixed to the anchor regions 17 and 27 of the vibrating bodies 13 and 23, which correspond to the portion indicated by reference numeral A1 in FIGS. 5 to 7, are included in areas where the amount of displacement is large when the vibrating bodies 13 and 23 resonate. The antinodes of vibration in the resonance modes of the vibrating bodies 13 and 23, which correspond to the portions indicated by reference numerals A2 and A3 in FIGS. 6 and 7, are also included in areas where the amount of displacement is large when the vibrating bodies 13 and 23 resonate. In step S13, the silicon oxide films 12, 22 of at least one of the first ends 15, 25 of the vibrating bodies 13, 23 and the antinodes of vibration in the resonance mode of the vibrating bodies 13, 23 may be set as the irradiation points of the electron beam EB. If a metal layer is present on the surfaces of the silicon oxide films 12, 22, the irradiation points of the electron beam EB are set to the exposed surface portions of the silicon oxide films 12, 22 that are not covered by the metal layer. The irradiation points of the electron beam EB are set to positions where a probe (not shown) connected to the actuators 10, 20 does not block the optical path of the electron beam EB. If the semiconductor chips that make up the actuators 10, 20 are individually divided and packaged, the irradiation points of the electron beam EB are set to positions that can be irradiated with the electron beam EB in a packaged state.

[0024] For example, in the actuator 10 of FIG. 1, when the vibration direction of the vibrating body 13 is the vertical direction Z, the resonating vibrating body 13 vibrates in the vibration modes shown in FIGS. 5 to 7 when the actuator 10 is viewed from the horizontal direction Y. In this case, a portion of the silicon oxide film 12 of FIG. 1 corresponding to at least one of the portions A1 to A3 of FIGS. 5 to 7 in the extension direction X is set as the irradiation point of the electron beam EB. As shown in FIG. 1, when the vibrating body 13 vibrates in the vertical direction Z, the main surface of the single crystal silicon 11 on which the silicon oxide film 12 is formed hits a surface that intersects with the vibration direction of the vibrating body 13. The irradiation point of the electron beam EB is set to the silicon oxide film 12 formed on the surface of the single crystal silicon 11 that intersects with the vibration direction of the vibrating body 13.

[0025] 1, when the vibration direction of the vibrating body 13 is the horizontal direction Y, the resonating vibrating body 13 vibrates in the vibration modes shown in Figures 5 to 7 when the actuator 10 is viewed from the up-down direction Z. In this case as well, a portion of the silicon oxide film 12 in the extension direction X that corresponds to at least one of the portions A1 to A3 in Figures 5 to 7 is set as the irradiation portion of the electron beam EB.

[0026] When the silicon oxide film 12 is irradiated with the electron beam EB, the electron beam EB may be irradiated at a plurality of locations spaced apart in the horizontal direction Y of the silicon oxide film 12.

[0027] For example, in the actuator 20 of FIG. 2, when the vibration direction of the vibrating body 23 is the vertical direction Z, the resonating vibrating body 23 vibrates in the vibration modes shown in FIGS. 5 to 7 when the actuator 20 is viewed from the horizontal direction Y. In this case, for example, the silicon oxide film 22 formed on the upper surface of the single crystal silicon 21 of FIG. 2, which intersects with the vibration direction of the vibrating body 23, is set as the silicon oxide film 22 to be irradiated with the electron beam EB. The silicon oxide film 22 formed on the lower surface of the single crystal silicon 21, which intersects with the vibration direction of the vibrating body 23, may also be included as the target of irradiation with the electron beam EB. Furthermore, the silicon oxide films 22 formed on both sides of the single crystal silicon 21 in the horizontal direction Y may also be included as the target of irradiation with the electron beam EB. A portion of the target silicon oxide film 22, which corresponds to at least one of the portions A1 to A3 of FIGS. 5 to 7 in the extension direction X, is set as the irradiation portion of the electron beam EB.

[0028] In the actuator 20 of FIG. 2, when the vibration direction of the vibrating body 23 is the horizontal direction Y, the resonating vibrating body 23 vibrates in the vibration modes shown in FIGS. 5 to 7 when the actuator 20 is viewed from the up-down direction Z. In this case, for example, the silicon oxide film 22 formed on both surfaces of the single crystal silicon 21 of FIG. 2 that intersect with the vibration direction of the vibrating body 23 is set as the silicon oxide film 22 to be irradiated with the electron beam EB. The silicon oxide film 22 formed on the upper surface of the single crystal silicon 21 may also be included in the targets to be irradiated with the electron beam EB. Furthermore, the silicon oxide film 22 formed on the lower surface of the single crystal silicon 21 may also be included in the targets to be irradiated with the electron beam EB. A portion of the target silicon oxide film 22 that corresponds to at least one of the portions A1 to A3 in FIGS. 5 to 7 in the extension direction X is set as the irradiation portion of the electron beam EB.

[0029] The vibration modes of the vibrating bodies 13, 23 to be referred to when setting the irradiation points of the electron beam EB on the silicon oxide films 12, 22 are not limited to the first to third bending modes shown in Figures 5 to 7, but may also include, for example, fourth or higher bending modes and butterfly modes.

[0030] 2, in the silicon oxide films 22 formed on both side surfaces of the single crystal silicon 21, the electron beam EB may be irradiated at multiple locations spaced apart in the vertical direction Z of the silicon oxide film 22. In the silicon oxide films 22 formed on the upper and lower surfaces of the single crystal silicon 21, the electron beam EB may be irradiated at multiple locations spaced apart in the horizontal direction Y of the silicon oxide film 22.

[0031] 1 and 2 resonate, the portions of the anchor regions 17 and 27 of the single crystal silicon 11 and 21 where the first ends 15 and 25 of the vibrating bodies 13 and 23 are fixed are also displaced, and a considerable amount of stress is applied due to the vibration of the vibrating bodies 13 and 23. Therefore, of the silicon oxide films 12 and 22 formed on the surfaces of the anchor regions 17 and 27 of the single crystal silicon 11 and 21, the portions corresponding to the portions where the first ends 15 and 25 of the vibrating bodies 13 and 23 are fixed may be added to the set targets for the irradiation points of the electron beam EB. If this portion is added to the set targets, at least one of all the set target portions of the silicon oxide films 12 and 22 is set as the irradiation point of the electron beam EB.

[0032] The irradiation conditions of the electron beam EB set in step S13 include, for example, at least one of the irradiation energy of the electron beam EB and the irradiation density of the electron beam EB with respect to the silicon oxide films 12, 22. The irradiation energy of the electron beam EB changes the beam diameter of the electron beam EB and the distribution positions and distribution ranges of the silicon portions 14, 24 formed in the silicon oxide films 12, 22 by irradiation with the electron beam EB. Changing the irradiation energy of the electron beam EB changes the size, or the distribution positions and distribution ranges of the silicon portions 14, 24 formed in the silicon oxide films 12, 22 at the locations irradiated with the electron beam EB. The amount of increase or decrease in the amount of silicon oxide and silicon resulting from the formation of the silicon portions 14, 24 by irradiation with the electron beam EB can be changed by adjusting the irradiation energy of the electron beam EB. By adjusting the irradiation energy of the electron beam EB, the increase or decrease in the amount of silicon oxide and silicon due to irradiation with the electron beam EB can be set to an amount corresponding to the magnitude of the difference between the temperature characteristics of the resonant frequencies of the vibrating bodies 13 and 23 measured in step S11 and the target temperature characteristics. The irradiation energy of the electron beam EB can be adjusted by at least one of the beam diameter, beam intensity, irradiation time, and irradiation location of the electron beam EB.

[0033] The irradiation density of the electron beam EB can be adjusted by changing the irradiation interval of the electron beam EB with respect to the silicon oxide films 12, 22. By adjusting the irradiation density of the electron beam EB, it is possible to adjust the distribution density of the silicon portions 14, 24 formed at the locations of the silicon oxide films 12, 22 irradiated with the electron beam EB. The irradiation interval of the electron beam EB may be adjusted by increasing or decreasing the number of locations irradiated with the electron beam EB as described with reference to FIGS. 5 to 7. When the electron beam EB is irradiated to multiple locations on the silicon oxide film 12 at intervals in the horizontal direction Y or the up-down direction Z, the irradiation interval of the electron beam EB may be adjusted by increasing or decreasing the interval in the horizontal direction Y or the up-down direction Z.

[0034] By adjusting the irradiation energy and irradiation density of the electron beam EB irradiated onto the silicon oxide films 12 and 22, the frequency temperature coefficient TCF3 of the vibrating bodies 13 and 23 can be changed so that the temperature characteristics of the resonant frequencies of the vibrating bodies 13 and 23 efficiently approach the target temperature characteristics.

[0035] In the manufacturing method of the actuators 10 and 20 according to the embodiment, the irradiation conditions of the electron beam EB to be set when the procedure of step S13 in FIG. 4 is first performed can be determined in advance through experiments or the like. The irradiation conditions of the electron beam EB may be determined, for example, for each difference between the temperature characteristics of the resonant frequency of the oscillating body 13 or 23 measured in step S11 and the target temperature characteristics. When the procedure of step S13 is performed for the second time or later, at least one of the irradiation energy and irradiation density of the electron beam EB is adjusted according to the difference between the temperature characteristics of the resonant frequency of the oscillating body 13 or 23 measured in the immediately preceding step S11 and the target temperature characteristics. The irradiation energy and irradiation density of the electron beam EB are increased, for example, if the difference between the measured temperature characteristics of the resonant frequency of the oscillating body 13 or 23 and the target temperature characteristics is large, and decreased, for example, if the difference is small.

[0036] In step S14, a reduction step is performed in which the silicon oxide films 12 and 22 are irradiated with the electron beam EB under the irradiation conditions for the electron beam EB set in step S13, and silicon portions 14 and 24 are formed by reducing the silicon oxide in the portions of the silicon oxide films 12 and 22 irradiated with the electron beam EB.

[0037] Although not shown in FIGS. 1 and 2 , the single crystal silicon 11, 21 has a portion (not shown) that remains after the vibrating bodies 13, 23 are formed by etching, separate from the vibrating bodies 13, 23 and the anchor regions 17, 27. The single crystal silicon 11, 21 in the portion (not shown) exists around the vibrating bodies 13, 23 except above, and is connected to the anchor regions 17, 27 of the single crystal silicon 11, 21. A gap (not shown) exists between the vibrating bodies 13, 23 and the single crystal silicon 11, 21 remaining around them. In the figures, a space (not shown) is formed in the single crystal silicon 11, 21 below the vibrating bodies 13, 23 because the single crystal silicon 11, 21 was removed when the vibrating bodies 13, 23 were formed by etching. Due to the presence of this space and the gap described above, the vibrating bodies 13, 23 vibrate in the vertical direction Z and the horizontal direction Y. In the reduction step of step S14, when the electron beam EB is irradiated onto the silicon oxide films 12, 22 other than those above the oscillators 13, 23, the electron beam EB can be irradiated onto the irradiation points through, for example, the gap or space described above.

[0038] After step S14, the procedures from the measurement step onward in step S11 described above are performed. The procedure in Fig. 4 is performed until the determination result in step S12 is "end," thereby repeating the irradiation of the electron beam EB onto the silicon oxide films 12 and 22 until the temperature characteristics of the resonant frequencies of the vibrating bodies 13 and 23 become the target temperature characteristics.

[0039] 4, the temperature characteristics of the resonant frequency of the vibrating bodies 13, 23 become the target temperature characteristics in which the resonant frequency does not change even when the temperature changes. According to the manufacturing method of the embodiment, the actuators 10, 20 are manufactured in which the resonant frequency of the vibrating bodies 13, 23 is constant regardless of temperature.

[0040] The process of irradiating the silicon oxide films 12, 22 with an electron beam EB to form the silicon oxide films 12, 22 by reducing silicon oxide to silicon portions 14, 24 can be performed even after the silicon oxide films 12, 22 have been formed on the surfaces of the single crystal silicon 11, 21. The process of forming the silicon oxide films 12, 22 on the surfaces of the single crystal silicon 11, 21 in excess of the target amount does not require strict control of the amount of silicon oxide films 12, 22 formed. The amount of silicon oxide films 12, 22 formed in excess of the target amount can be adjusted later to an appropriate amount by adjusting the amount of silicon portions 14, 24 reduced from silicon oxide to silicon by irradiation with the electron beam EB. Therefore, the manufacturing method of the embodiment makes it easy to manufacture actuators 10, 20 having vibrating bodies 13, 23 with resonant frequencies with target temperature characteristics using semiconductor manufacturing technology.

[0041] In the manufacturing method of the embodiment, even if the silicon oxide films 12, 22 are formed in an amount greater than calculated due to variations in the finish, the silicon oxide films 12, 22 after formation can be adjusted to the target amount by irradiating them with the electron beam EB, and can be used to manufacture the actuators 10, 20.

[0042] The actuators 10 and 20 manufactured by the manufacturing methods described in the above embodiments can be used in, for example, resonators and oscillators.

[0043] The resonator has the actuators 10 and 20 shown in FIGS. 1 and 2 as transducers. The resonator vibrates the vibrating bodies 13 and 23 in response to an input signal, and converts the vibration of the vibrating bodies 13 and 23 to generate a high-frequency signal. The actuators 10 and 20 of the resonator have metal layers as electrodes on the surfaces of the silicon oxide films 12 and 22. The metal layers as electrodes include, for example, the metal layer 18 shown in FIG. 1. The resonator may be in the form of a semiconductor chip that constitutes the actuators 10 and 20, or in the form of a device in which the semiconductor chip and its external wiring, etc. are sealed with a mold resin.

[0044] 8 is a diagram illustrating an example of an oscillator according to an embodiment. The oscillator 100 includes, for example, actuators 10 and 20 and a dedicated circuit 30. The oscillator 100 includes vibrating bodies 13 and 23 of the actuators 10 and 20 as vibrators. The dedicated circuit 30 includes an oscillation sustaining circuit that mechanically vibrates the vibrating bodies 13 and 23. The oscillation sustaining circuit may include, for example, a charge pump, a phase-locked loop, etc. The oscillator 100 may be a MEMS device.

[0045] In the above embodiments, the vibrating bodies 13, 23 have been described as having a cantilever structure. However, the manufacturing method of the present disclosure is also applicable to an actuator having a vibrating body with a membrane structure in which the first ends 15, 25 and second ends 16, 26 of the vibrating bodies 13, 23 are supported by anchor regions 17, 27 of the single crystal silicon 11, 21, respectively.

[0046] In the above embodiments, the actuators 10 and 20 and their manufacturing methods have been described as examples of transducers and their manufacturing methods. The transducer to which the present disclosure is applied may include, other than actuators, for example, a diaphragm-type pressure sensor that outputs an electrical signal corresponding to the vibration of a vibrating body.

[0047] Although the present disclosure has been described in detail above, it will be apparent to those skilled in the art that the present disclosure is not limited to the embodiments described herein. One or more elements of one embodiment may be combined with one or more elements of another embodiment. The present disclosure can be implemented in modified and altered forms without departing from the spirit and scope of the present disclosure, as defined by the claims. Therefore, the description of the present disclosure is intended to be illustrative and explanatory and is not intended to be limiting of the present disclosure.

[0048] (Addendum) The technical ideas that can be understood from the present disclosure are described below. Note that, for the purpose of aiding understanding and not intending to be limiting, the components described in the appendices are given the reference numerals of the corresponding components in the embodiments. The reference numerals are shown as examples to aid understanding, and the components described in each appendix should not be limited to the components indicated by the reference numerals.

[0049] (Appendix 1) The transducers 10 and 20 of Appendix 1 include single crystal silicon 11 and 21 and silicon oxide films 12 and 22. The single crystal silicon 11 and 21 have anchor regions 17 and 27 and vibrating bodies 13 and 23 supported by the anchor regions 17 and 27. The silicon oxide films 12 and 22 are formed on the surfaces of the single crystal silicon 11 and 21. The silicon oxide films 12 and 22 are provided with silicon portions 14 and 24 reduced from silicon oxide.

[0050] The silicon portions 14, 24 can be formed by irradiating the silicon oxide films 12, 22 with an electron beam EB to reduce the silicon oxide portions 12, 22 irradiated with the electron beam EB from silicon oxide to silicon. The process of reducing the silicon oxide portions 12, 22 irradiated with the electron beam EB from silicon oxide to silicon can be performed even after the silicon oxide films 12, 22 have been formed on the surfaces of the single crystal silicon 11, 21. When forming the silicon oxide films 12, 22 on the surfaces of the single crystal silicon 11, 21, it is sufficient to form the silicon oxide films 12, 22 in excess, and strict control of the amount of the silicon oxide films 12, 22 formed is not required. The amount of silicon oxide films 12, 22 formed in excess of the target amount can be adjusted later to an appropriate amount by adjusting the amount of silicon portions 14, 24 reduced from silicon oxide to silicon by irradiation with the electron beam EB. According to the transducers 10 and 20 described in Supplementary Note 1, the transducers 10 and 20 having the vibrating bodies 13 and 23 with the resonant frequency of the target temperature characteristics can be configured to be easily manufactured using semiconductor manufacturing technology.

[0051] (Appendix 2) In the transducers 10 and 20 described in Appendix 1, the vibrating bodies 13 and 23 have a cantilever structure in which the first ends 15 and 25 are fixed to the anchor regions 17 and 27. The transducers 10 and 20 having the vibrating bodies 13 and 23 with a cantilever structure can be easily manufactured using semiconductor manufacturing technology.

[0052] (Appendix 3) In the transducers 10 and 20 described in Supplementary Note 2, the silicon portions 14 and 24 are provided in at least one portion of the silicon oxide films 12 and 22. The portion where the silicon portions 14 and 24 are provided is set to at least one of the first ends 15 and 25 of the vibrating bodies 13 and 23, the antinodes of vibration of the vibrating bodies 13 and 23 in a resonance mode specific to the vibrating bodies 13 and 23, and the anchor regions 17 and 27. By providing the silicon portions 14 and 24 in at least one of these portions, it is possible to increase the efficiency of approximating the temperature characteristics of the resonant frequency of the vibrating bodies 13 and 23 to the target temperature characteristics by reducing silicon oxide to silicon.

[0053] (Appendix 4) In the transducers 10 and 20 described in Supplementary Note 1 or 2, silicon portions 14 and 24 are provided in silicon oxide films 12 and 22 on the main surfaces of the single crystal silicon 11 and 21. By irradiating the silicon oxide films 12 and 22 on the main surfaces of the single crystal silicon 11 and 21 with an electron beam EB, the temperature characteristics of the resonant frequencies of the vibrating bodies 13 and 23 vibrating in a direction intersecting the main surfaces of the single crystal silicon 11 and 21 can be made to greatly approximate the target temperature characteristics.

[0054] (Appendix 5) In the transducers 10 and 20 described in Supplementary Note 1 or 2, silicon portions 14 and 24 are provided in silicon oxide films 12 and 22 on a plurality of surfaces including the main surfaces of the single crystal silicon 11 and 21. By irradiating the silicon oxide films 12 and 22 on the plurality of surfaces of the single crystal silicon 11 and 21 with an electron beam EB, the temperature characteristics of the resonant frequencies of the vibrating bodies 13 and 23 vibrating in directions intersecting with each surface can be made to greatly approach the target temperature characteristics.

[0055] (Appendix 6) The surface acoustic wave filter described in Supplementary Note 4 includes the transducer 10, 20 described in any one of Supplementary Notes 1 to 5, and extracts an electrical signal in a predetermined frequency band from an input signal by the electrodes 18 on the vibrating bodies 13, 23 of the transducers 10, 20. The surface acoustic wave filter including the transducers 10, 20 having the vibrating bodies 13, 23 can be configured to be easily manufactured using semiconductor manufacturing technology.

[0056] (Appendix 7) The oscillator 100 of Supplementary Note 7 has, as an oscillator, the vibrating body 13, 23 of the transducer 10, 20 described in any one of Supplementary Notes 1 to 5. The oscillator 100 including the transducer 10, 20 having the vibrating body 13, 23 as an oscillator can be configured to be easily manufactured using semiconductor manufacturing technology.

[0057] (Appendix 8) Supplementary note 8 provides a method for manufacturing transducers 10, 20 having vibrating bodies 13, 23 supported by anchor regions 17, 27. The method for manufacturing transducers 10, 20 includes a measurement step S11 and a reduction step S14. In the measurement step S11, the vibrating bodies 13, 23 are vibrated to measure the temperature characteristics of the resonant frequencies of the vibrating bodies 13, 23. In the reduction step S14, if the measured temperature characteristics are not the target temperature characteristics, an electron beam EB is irradiated onto silicon oxide films 12, 22 on the surfaces of single crystal silicon 11, 21 formed on the transducers 10, 20. By irradiating the electron beam EB, silicon portions 14, 24 are formed by reducing the silicon oxide at the locations of the silicon oxide films 12, 22 irradiated by the electron beam EB.

[0058] The process of irradiating the silicon oxide films 12, 22 with an electron beam EB to form the silicon oxide films 12, 22 by reducing silicon oxide to silicon portions 14, 24 can be performed even after the silicon oxide films 12, 22 have been formed on the surfaces of the single crystal silicon 11, 21. The process of forming the silicon oxide films 12, 22 on the surfaces of the single crystal silicon 11, 21 in excess of the target amount does not require strict control of the amount of silicon oxide films 12, 22 formed. The amount of silicon oxide films 12, 22 formed in excess of the target amount can be adjusted to an appropriate amount later by adjusting the amount of silicon portions 14, 24 reduced from silicon oxide to silicon by irradiation with the electron beam EB. The manufacturing method of Appendix 8 makes it easy to manufacture transducers 10, 20 having vibrating bodies 13, 23 with resonant frequencies with target temperature characteristics using semiconductor manufacturing technology.

[0059] (Appendix 9) In the method for manufacturing the transducers 10, 20 described in Appendix 8, an electron beam EB is irradiated to at least one portion of the silicon oxide film 12, 22. The portion to be irradiated with the electron beam EB is set to at least one of the first ends 15, 25 of the vibrating bodies 13, 23, the antinodes of vibration of the vibrating bodies 13, 23 in a resonance mode specific to the vibrating bodies 13, 23, and the anchor regions 17, 27. By irradiating at least one of these portions with the electron beam EB, it is possible to increase the efficiency of bringing the temperature characteristics of the resonant frequency of the vibrating bodies 13, 23 closer to the target temperature characteristics by reducing silicon oxide to silicon.

[0060] (Appendix 10) In the method for manufacturing the transducers 10 and 20 described in Supplementary Note 8 or 9, the irradiation energy of the electron beam EB is adjusted based on the difference between the measured temperature characteristics of the resonant frequency of the vibrating bodies 13 and 23 and the target temperature characteristics. By adjusting the irradiation energy of the electron beam EB, the increase or decrease in the amount of silicon oxide and silicon due to irradiation with the electron beam EB can be set to an amount corresponding to the magnitude of the difference between the temperature characteristics of the resonant frequency of the vibrating bodies 13 and 23 measured in step S11 and the target temperature characteristics.

[0061] (Appendix 11) In the method for manufacturing the transducers 10 and 20 described in Appendix 10, the irradiation energy of the electron beam EB is adjusted by at least one of the beam diameter, beam intensity, irradiation time, and irradiation location of the electron beam EB. The irradiation energy of the electron beam EB can be adjusted by at least one of the beam diameter, beam intensity, irradiation time, and irradiation location of the electron beam EB. [Explanation of symbols]

[0062] 10, 20 Actuators (transducers, surface acoustic wave filters) 11, 21 Single crystal silicon 12, 22 Silicon oxide film 13, 23 Vibration body 14, 24 Silicone part 15 1st end 17, 27 Anchor region 18 Metal layer (electrode) 100 Oscillators A1 First end A2, A3 vibration antinode EB electron beam

Claims

1. Single crystal silicon having an anchor region and a vibrator supported by the anchor region; a silicon oxide film formed on the surface of the single crystal silicon; It is equipped with The silicon oxide film is provided with a silicon portion reduced from silicon oxide. Transducer.

2. The transducer according to claim 1 , wherein the vibrating body has a cantilever structure with a first end fixed to the anchor region.

3. 3. The transducer according to claim 2, wherein the silicon portion is provided in the silicon oxide film in at least one of the first end portion of the vibrating body, an antinode portion of the vibration of the vibrating body in a resonance mode specific to the vibrating body, and a portion of the anchor region.

4. A resonator comprising the transducer according to any one of claims 1 to 3, which generates a high frequency signal of a predetermined frequency from a signal input to an electrode on a vibrating body of the transducer.

5. An oscillator having the vibrating body of the transducer according to any one of claims 1 to 3 as a vibrator.

6. A method for manufacturing a transducer having a vibrating body supported by an anchor region, comprising: a measuring step of vibrating the vibrating body and measuring the temperature characteristics of the resonant frequency of the vibrating body; a reduction step of irradiating an electron beam onto a silicon oxide film on the surface of the single crystal silicon forming the transducer, to form a silicon portion reduced from silicon oxide at a portion of the silicon oxide film irradiated with the electron beam, if the measured temperature characteristic is not a target temperature characteristic; It contains The measuring step and the reducing step are repeated until the measured temperature characteristic matches the target temperature characteristic. A method for manufacturing a transducer.

7. 7. The method for manufacturing a transducer according to claim 6, wherein the vibrating body has a cantilever structure with a first end fixed to the anchor region, and in the reduction step, the electron beam is irradiated onto the silicon oxide film in at least one of a portion of the first end of the vibrating body, an antinode of vibration of the vibrating body in a resonance mode specific to the vibrating body, and a portion of the anchor region.

8. 8. The method for manufacturing a transducer according to claim 6, further comprising adjusting irradiation energy of the electron beam based on a difference between the measured temperature characteristic and the target temperature characteristic.

9. The method for manufacturing a transducer according to claim 8, wherein the irradiation energy is adjusted by at least one of the beam diameter, beam intensity, irradiation time, and irradiation location of the electron beam.

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