JP4773836B2 - Thin film bulk acoustic wave oscillator and manufacturing method thereof - Google Patents

Description

  The present invention relates to a thin film bulk acoustic wave oscillator and a method for manufacturing the same, and more particularly to a high frequency oscillator in which an active element such as a transistor and a thin film bulk acoustic wave resonator are integrated on the same substrate, a voltage variable high frequency oscillator, and an oscillator thereof. Integrated circuit and a manufacturing method thereof.

  An oscillator is an element frequently used in various devices or circuits for a clock source, a local oscillator for frequency conversion, and other applications.

  Crystal and oscillators are used for watches and cellular phones that require the most accurate oscillation source. The crystal resonator is formed by cutting the crystal plane at a specific angle after crystal growth and then depositing electrodes on both sides. Since the frequency is determined by the thickness and shape of the vibrator and the speed of the acoustic wave in the quartz crystal is relatively slow, the upper limit of the current technology is to generate a frequency of about 155 MHz in the high frequency region.

  As an oscillator that can oscillate in a wide frequency range from a low frequency to a high frequency, an LC oscillator using an inductor and a capacitor and an RC oscillator using a resistor and a capacitor are used in various circuits and applications. However, these oscillators have poor oscillation frequency purity and temperature stability, and in many cases, sufficient performance cannot be obtained depending on applications.

  A ferroelectric material such as PZT is used in order to obtain oscillation with a higher frequency purity than LC oscillators and RC oscillators, although it does not require the accuracy of a quartz crystal oscillator from several hundreds of kHz to several tens of MHz. The ceramic oscillator used is used.

  In order to obtain oscillation with high frequency purity in a high frequency range from several hundred MHz band to 1 GHz, an oscillator using a SAW vibrator is used.

  Furthermore, in a high frequency GHz band, an oscillator using a resonator composed of a dielectric resonator, a coaxial line, and a microstrip line is used. It is difficult to reduce the size of an oscillator using a dielectric or a line, and it is difficult to make an oscillator together with a transistor circuit on a silicon substrate except for an LC oscillator.

US Pat. No. 5,075,641 IEEE Microwave Symposium Digest, Vol. 2,2003, p717-720

  In recent years, it has become possible to grow a piezoelectric material thin film with good crystallinity by the progress of thin film deposition technology. Using this technique, a high-frequency thin film bulk acoustic wave filter and a thin film bulk acoustic wave duplexer (demultiplexer) are manufactured.

  Non-Patent Document 1 is an example in which an active element and a resonator are separately manufactured and then connected on an aluminum substrate and actually oscillated at 2 GHz.

  As described in Patent Document 1, an oscillator in which an active element and a thin film bulk acoustic wave resonator are formed on the same substrate has been proposed.

  However, the lower side of the thin film bulk acoustic wave resonator is hollowed by etching from the back side, making it difficult to ensure reliability because it is brittle in structure, difficult to improve yield in manufacturing, and harmful to the oscillator There are drawbacks in that spurious vibrations are likely to occur and nothing can be placed under the resonator, including wiring.

  Accordingly, an object of the present invention is to provide a thin film bulk acoustic wave oscillator that can be integrated and miniaturized and that has high reliability, and a method for manufacturing the same.

  Another object of the present invention is to provide a thin-film bulk acoustic wave oscillator that does not require an external oscillator and has high frequency purity in a high-frequency band from several hundred MHz to around 10 GHz, and a method for manufacturing the same. is there.

  Another object of the present invention is to provide a thin film bulk acoustic wave oscillator capable of having a wide frequency variable range and a method for manufacturing the same.

  The present invention relates to a thin film bulk acoustic wave oscillator, in which a circuit element portion including at least a transistor element and a capacitor element is formed on a substrate, and the circuit element portion is made of a high acoustic impedance material. An acoustic mirror part in which an acoustic mirror layer is formed by alternately stacking thin films and thin films made of a low acoustic impedance material, and a piezoelectric body directly above the area of the acoustic mirror part where the acoustic mirror layer is formed A thin film bulk acoustic wave resonator comprising a thin film and two electrode portions sandwiching the piezoelectric thin film from above and below is formed, and the thin film bulk acoustic wave resonator is disposed on the substrate side via the acoustic mirror layer. A resonator unit acoustically separated from the circuit element, the circuit element of the circuit element unit, and the thin film bulk acoustic wave resonator of the resonance unit; By electrically wired connection, constituting the thin film bulk acoustic wave oscillator.

  The capacitive element may be a fixed capacitive element or a variable capacitive element for setting the oscillation frequency of the thin film bulk acoustic wave resonator to a predetermined value.

  The piezoelectric thin film may be aluminum nitride.

  The circuit element may be a silicon MOS transistor, a silicon bipolar transistor, or a silicon germanium transistor.

  The wiring connection distance between the thin film bulk acoustic wave resonator and the capacitive element may be set to be longer than the wiring connection distance between the thin film bulk acoustic wave resonator and the transistor element.

  A plurality of the thin film bulk acoustic wave resonators may be used, and the thin film bulk acoustic wave resonators may be connected in parallel.

  Changes in mechanical vibration and capacitive coupling due to the thin film bulk acoustic wave resonators do not affect the oscillation frequency characteristics, and the thin film bulk acoustic wave resonators are disposed immediately above the circuit elements. Also good.

  When the capacitive element is connected to the two electrode portions of the thin film bulk acoustic wave resonator, the capacitance value or the number of elements of the other capacitive element is asymmetric with respect to the capacitance value or the number of elements of one capacitive element. It may be.

  When the thin film bulk acoustic wave resonator includes a plurality of thin film bulk acoustic wave resonators, the thin film bulk acoustic wave resonators may have different resonance frequencies.

  The capacitive element may be connected to at least one of the electrode portions of the thin film bulk acoustic wave resonator.

  It may be a part of an integrated circuit on a semiconductor substrate. The present invention relates to a manufacturing method of manufacturing a thin film bulk acoustic wave oscillator using a microfabrication technique and a thin film formation technique, and a circuit element portion including at least a transistor element and a capacitor element is formed on a substrate. And an acoustic mirror portion having an acoustic mirror layer formed by alternately stacking a thin film made of a high acoustic impedance material and a thin film made of a low acoustic impedance material on the circuit element portion. A thin film bulk acoustic wave resonator comprising: a step of forming; and a piezoelectric thin film and two electrode portions sandwiching the piezoelectric thin film from above and below immediately above a region of the acoustic mirror portion where the acoustic mirror layer is formed And acoustically separating the thin film bulk acoustic wave resonator from the circuit element on the substrate side via the acoustic mirror layer Forming a pendulum part; and electrically wiring-connecting the circuit element of the circuit element part and the thin film bulk acoustic wave resonator of the resonator part, thereby providing a thin film bulk acoustic wave An oscillator manufacturing method is provided.

  According to the present invention, a circuit element portion in which a circuit element of a transistor or a capacitance is formed on a substrate using a microfabrication technique, and an upper layer of the circuit element portion that is acoustically separated from the circuit element portion An acoustic mirror layer is formed by alternately stacking thin films made of high acoustic impedance material and thin film made of low acoustic impedance material in the region, and formed using a thin film forming technique directly on the acoustic mirror layer. A thin film bulk acoustic wave resonator having a structure in which a piezoelectric thin film is sandwiched between an upper electrode layer and a lower electrode layer and acoustically separated from the substrate side. Since the oscillation circuit and the resonator are built on the same substrate by wiring connection using microfabrication technology, the integrated and miniaturized one-chip oscillator and voltage enable It is possible to fabricate the oscillator.

  Further, according to the present invention, it is possible to manufacture an oscillator with high frequency purity in a high frequency band from several hundreds of MHz to around 10 GHz and with low spurious and high reliability.

  Furthermore, according to the present invention, a thin film bulk acoustic wave voltage variable oscillator having a wide frequency variable range can be manufactured by connecting a plurality of divided resonators in parallel.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[First example]
A first embodiment of the present invention will be described with reference to FIGS.
<Cross-section structure>
FIG. 1 shows an example of the structure of a thin film bulk acoustic wave oscillator 100 according to the present invention.

  The thin film bulk acoustic wave oscillator 100 includes a circuit element unit 110 in which a circuit element 111 is formed on a substrate 1 (here, a silicon substrate), and an acoustic mirror unit 120 in which an acoustic mirror layer 121 is formed on the circuit element unit 110. And a resonator unit 130 in which a thin film bulk acoustic wave resonator 131 is formed on the acoustic mirror unit 120.

  Hereinafter, the structure of each part is demonstrated concretely.

(Circuit element part)
In the circuit element unit 110, a circuit element 111 including at least a transistor element and a capacitor element is formed on the silicon substrate 1.

  In this example, a transistor 2, a capacitance 3, and a wiring layer 4 are formed on a silicon substrate 1. A well 2a structure is formed on the silicon substrate 1, and a MOS transistor 2 is formed as a transistor by performing gate oxidation and gate formation, and then performing source / drain formation.

(Acoustic mirror part)
The acoustic mirror unit 120 is located above the circuit element unit 110. However, in the example of FIG. 1, the acoustic mirror layer 121 is composed of a thin film 5a composed of a high acoustic impedance material and a low acoustic impedance material corresponding to a region not directly above the region where the circuit element 111 is formed. The thin films 5b to be formed are alternately stacked. The acoustic mirror layer 121 plays a role of preventing the acoustic wave of the resonator from leaking to the substrate 1, and the function thereof will be described later.

(Resonant part)
The resonating unit 130 is a thin film bulk acoustic wave resonance composed of a piezoelectric layer 7 made of a piezoelectric thin film, a lower electrode 6, and an upper electrode 8 immediately above a region where the acoustic mirror layer 121 of the acoustic mirror unit 120 is formed. A child 131 is formed.

  The thin film bulk acoustic wave resonator 131 has a structure that is acoustically separated from the substrate 1 and the circuit element 111 on the substrate via the acoustic mirror layer 121.

  The upper side of the upper electrode 8 has a structure in which acoustic energy is confined as a free end by using a hollow package of an air layer. The lower electrode 6 has a structure in which an elastic wave is confined by a reflection structure using the acoustic mirror layer 121.

  As the piezoelectric material of the piezoelectric layer 7, aluminum nitride and zinc oxide are useful. Although not limited to these two materials, aluminum nitride is particularly preferable because of its low loss in the high frequency region, temperature characteristics, and the fact that it is a material that does not pose a problem even if it is put into a silicon semiconductor device production line. .

  The lower electrode 6 can be selected from platinum, molybdenum, aluminum, ruthenium, tungsten and the like according to the purpose.

  The upper electrode 8 can be selected from aluminum, molybdenum and the like according to the purpose.

(Wiring section)
The circuit element 111 of the circuit element unit 110 and the thin film bulk acoustic wave resonator 131 of the resonance unit 130 are electrically connected by wiring. In the case of the example of FIG. 1, a capacitance 3 as a capacitive element is connected to one electrode portion of the thin film bulk acoustic wave resonator 131, that is, the lower electrode 6 or the upper electrode 8.

  In this example, the capacitance 3 is connected to the electrode of the upper electrode 8.

  As described above, the thin film bulk acoustic wave resonator 131 is formed on the silicon substrate 1, and the circuit element 111 on the substrate side and the upper and lower electrodes 8 and 6 on the resonator side are connected by wiring. .

<Layout>
FIG. 2 shows an example of the layout of the thin film bulk acoustic wave oscillator 100 of FIG.
21 is a thin film bulk acoustic wave resonator (thin film bulk acoustic wave resonator 131 in FIG. 1).
Reference numeral 22 denotes an inverter (consisting of the transistor 2 and the like in FIG. 1).
Reference numeral 23 denotes a capacitance (consisting of the capacitance 3 and the like in FIG. 1).
Reference numeral 24 denotes a polysilicon resistor.
Reference numerals 25 and 26 denote peripheral circuits such as an output driver and electrode pads.

  The thin film bulk acoustic wave resonator 21 and the capacitance 23 are preferably disposed near the inverter 22 to reduce wiring resistance and parasitic capacitance. However, on the other hand, it is necessary for the frequency adjusting capacitance 23 to avoid the deterioration of the phase noise characteristic due to the interference of the mechanical vibration by the thin film bulk acoustic wave resonator 21 and the coupling through the parasitic capacitance. .

  Therefore, the distance between the capacitance 23 and the thin film bulk acoustic wave resonator 21 is preferably longer than the distance between the capacitance 23 and the inverter 22.

<Circuit example>
FIG. 3 shows an example of the circuit configuration of the thin film bulk acoustic wave oscillator 100 of FIG.
Here, a Pierce oscillation circuit often used in a crystal oscillator is taken as an example.
Reference numeral 13 denotes an inverter (inverter 22 in FIG. 2), which has a function of performing inverting amplification.
A resistor 14 is used to control the gain of the amplifier.
Reference numeral 15 denotes a thin film bulk acoustic wave resonator (thin film bulk acoustic wave resonator 131 in FIG. 1), which plays a role of extracting only a specific component from the output side and feeding it back to the input side.
Reference numeral 16 denotes a capacitance (capacitance 3 in FIG. 1).

  Owing to the action of the thin film bulk acoustic wave resonator 15 and the capacitance 16, the oscillation grows at a frequency at which the feedback signal is 180 degrees in phase, and after reaching the saturation value, the oscillation becomes constant and stable.

  In addition to this example, Colpitts oscillation circuits, Hartley oscillation circuits, and modified circuits thereof can be used as the basic form of an oscillation circuit using a resonator or an inductor and a capacitor. It is possible.

<Frequency dependence>
FIG. 4 shows the frequency dependence of the admittance near the resonance frequency in the thin film bulk acoustic wave oscillator 100 shown in FIG.

  In FIG. 4, the point 17 at which the left admittance is maximum is a resonance point, and the point 18 at which the right admittance is minimum and the impedance is maximum is called an antiresonance point.

  A region between the resonance point 17 and the antiresonance point 18 is a region where the resonator operates as an inductor. The oscillation frequency is mainly determined by the resonator, but the oscillation frequency changes due to the influence of the capacitance of the oscillation circuit.

<Piezoelectric effect>
The piezoelectric effect of the piezoelectric layer 7 constituting the thin film bulk acoustic wave resonator 131 of FIG. 1 will be described.

  When a voltage is applied between the upper and lower electrodes 8 and 6 from the outside of FIG. 1 due to the piezoelectric effect of the piezoelectric body, an elastic wave (acoustic wave) is applied to the resonator composed of the upper and lower electrodes 8 and 6 and the piezoelectric layer 7. ) Is induced.

  A standing wave is generated under a frequency condition in which the thickness of the piezoelectric body structure including the electrode is equal to the half wavelength of the elastic wave, causing a resonance phenomenon, and the resonator exhibits properties as an inductor. In the other frequency regions, the characteristics of capacitors are mainly shown. Due to its characteristics, it is suitable for oscillation at a narrow specific frequency, and has a Q value much higher than that of a normal LC oscillation circuit, and high-purity oscillation can be obtained.

  In addition, since the elastic wave is 5 to 6 orders of magnitude slower than the electromagnetic wave, the wavelength is short, and it is possible to cause a resonance phenomenon with an element much smaller than an element that handles the electromagnetic wave as it is.

  If the thin film bulk acoustic wave resonator 131 is formed on the silicon substrate 1 as in this example, it is smaller and more reliable than the case where the conventional piezoelectric vibrator and the oscillation circuit are separately created and connected. It is possible to manufacture a high-use and easy-to-use oscillator.

<Acoustic mirror effect>
The acoustic mirror effect by the acoustic mirror layer 121 which comprises the acoustic mirror part 120 of FIG. 1 is demonstrated.

  In the example of the thin film bulk acoustic wave oscillator 100 of FIG. 1, the example in which the acoustic mirror layer 121 is used to confine the acoustic wave is shown.

  On the other hand, as described in the prior art, a similar oscillator can be formed by hollowing the lower portion of the lower electrode 6 using the surface micromachining technique.

  However, as in the present invention, it is considered that the configuration below the thin film bulk acoustic wave resonator 131 as an acoustic mirror is more preferable based on the following three reasons.

  The first reason is that the method of confining with an acoustic mirror can suppress an extra oscillation called spurious. Spurious is a factor that lowers the quality of oscillation, but spurious is easily generated in the structure where the lower part is hollow and the resonator is supported at the end, and it is difficult to suppress the spurious.

  The second reason is that a structure without a hollow portion has higher resistance to dropping and impact, and is advantageous in terms of reliability. This is an important characteristic for portable devices that are often carried.

  The third reason is that a smaller oscillator chip can be obtained by forming the resonator on a portion of the transistor circuit that does not affect the oscillation characteristics. On the other hand, in the case of a hollow structure, a part of the circuit structure cannot be placed under the resonator. One of the advantages of an oscillator using this acoustic mirror is that it is possible to make a structure in which a circuit and a resonator are overlapped, and further miniaturization is possible, although a certain amount of trial and error is required. As is well known, downsizing is not only very advantageous for mounting when it is put in a mobile device etc., but in the case of semiconductor elements and parts, many products can be made from the same wafer, so the cost per product It is also a very effective means for lowering.

  However, in the case of confinement using the acoustic mirror layer 121, wiring must be performed through the thickness of the acoustic mirror. If this portion is thick, the connection between the thin film bulk acoustic wave resonator 131 and the transistor 2 becomes difficult. Therefore, it is important to produce an acoustic mirror that is as thin as possible and has a high performance.

  For this production, a material having a large acoustic impedance difference between the thin film 5a made of the high acoustic impedance material and the thin film 5b made of the low acoustic impedance material and a low acoustic velocity of both materials is selected. It is important to do.

[Second example]
A second embodiment of the present invention will be described with reference to FIGS. In addition, about the same part as the 1st example mentioned above, the description is abbreviate | omitted and the same code | symbol is attached | subjected.

<Cross-section structure>
FIG. 5 shows a modification of the thin film bulk acoustic wave oscillator 100 shown in FIG. 1 of the first example described above.

  In this example, the transistor element which is the circuit element 111 is configured by the bipolar transistor 12.

  A buried n + layer 10 is formed on the silicon substrate 1, an epi layer 11 is grown on the buried n + layer 10, and a bipolar transistor 12 including a collector, a base, and an emitter is formed on the epi layer 11.

  The transistor used for the oscillation circuit may be a silicon bipolar transistor, a silicon MOS transistor, a silicon germanium heterojunction bipolar transistor, or any other high-speed transistor that can be formed on a silicon substrate. An optimum transistor may be selected depending on the application and purpose.

  Further, the on-chip capacitance 3 as a capacitive element which is the circuit element 111 is formed by sandwiching a dielectric layer such as a silicon oxide film between polysilicon layers.

  However, the capacitor element is not limited to such a formation method, and may be formed by sandwiching between a MOS capacitor and a metal, or using surface micromachining technology.

  In addition, the polysilicon resistor 24 as a resistance element which is the circuit element 111 is formed by depositing polysilicon on a silicon oxide film, and then adjusting the dose so as to obtain a predetermined resistivity and implanting dopant by ion implantation. After implantation and annealing, a pattern is formed. A desired resistance value can be obtained by adjusting the length and width of the pattern during layout.

<Layout>
FIG. 6 shows an example of the layout of the thin film bulk acoustic wave oscillator 100 of FIG.

  This example is an example in which a part of the thin film bulk acoustic wave resonator 21 divided into a plurality is arranged directly on another circuit element, for example, the polysilicon resistor 24. The two resonators arranged on the lower side of the transistor section (inverter) 22 on the layout of FIG. The other basic configuration of the layout is the same as the layout example of FIG.

  By arranging in this way, the chip area can be reduced, and a thin film bulk acoustic wave oscillator having a small size and cost competitiveness can be manufactured.

[Third example]
A third embodiment of the present invention will be described with reference to FIGS. In addition, about the same part as each example mentioned above, the description is abbreviate | omitted and the same code | symbol is attached | subjected.

<Voltage variable oscillator>
FIG. 7 shows an example of the configuration of the thin film bulk acoustic wave voltage variable oscillator 200.

  The thin film bulk acoustic wave voltage variable oscillator 200 is configured by using the MOS transistor 2 as a transistor element, similarly to the thin film bulk acoustic wave oscillator 100 of FIG. 1 described above. explain.

  In this example, a variable capacitor is used as the capacitor.

  Here, an example is shown in which a MOS varactor is used as the variable capacitance element. The MOS varactor is an element that utilizes a change in capacitance between the gate and the substrate 1 by an applied bias with a gate oxide film interposed therebetween.

  The variable capacitance element is not limited to a MOS varactor, and a variable capacitance element configured by a diode varactor or manufactured by using surface micromachining technology may be used.

<Circuit example>
FIG. 8 shows an example of the circuit configuration of the thin film bulk acoustic wave voltage variable oscillator 200 of FIG.

  The thin film bulk acoustic wave voltage variable oscillator 200 has substantially the same configuration as that of FIG. 3 described above, but a varactor 19 (for example, a MOS varactor 20 of FIG. 7) as a voltage variable capacitance element is connected instead of the capacitor.

  When the capacitance value of the varactor 19 is changed by voltage control, an oscillator capable of controlling the frequency by voltage can be created by utilizing the fact that the oscillation frequency is shifted by this capacitance value.

  Although not included in the circuit of FIG. 8, the range of the variable frequency can be further expanded by connecting an on-chip inductor in series to the thin film bulk acoustic wave resonator 15. However, it should be noted that since the Q value of the on-chip inductor is low, the purity of oscillation is lowered.

[Fourth example]
A fourth embodiment of the present invention will be described with reference to FIG. In addition, about the same part as each example mentioned above, the description is abbreviate | omitted and the same code | symbol is attached | subjected.

<Voltage variable oscillator>
FIG. 9 shows a modification of the thin film bulk acoustic wave oscillator 200 shown in FIG. 7 of the third example.

  The thin film bulk acoustic wave voltage variable oscillator 200 is configured using variable capacitance elements (for example, the MOS varactor 20 in FIG. 7, the varactor 19 in FIG. 8, etc.) in the same manner as the thin film bulk acoustic wave oscillator 200 in FIG. However, different parts from the configuration of FIG. 7 will be described below.

  In this example, the bipolar transistor 12 as shown in FIG. 5 of the second example is used as the transistor element.

  With such a configuration, an oscillator capable of controlling the frequency with a voltage as in the third example can be created using the bipolar transistor 12.

[Fifth Example]
A fifth embodiment of the present invention will be described with reference to FIGS. In addition, about the same part as each example mentioned above, the description is abbreviate | omitted and the same code | symbol is attached | subjected.

  This example is an example of a circuit in which a plurality of thin film bulk acoustic wave resonators are connected in parallel.

  In the following description, a thin film bulk acoustic wave voltage variable oscillator capable of variable voltage is used as a thin film bulk acoustic wave resonator, and a circuit using a variable capacitive element as a capacitive element is taken as an example.

  FIG. 10 shows an example of the circuit configuration of the thin film bulk acoustic wave voltage variable oscillator 300.

  The thin film bulk acoustic wave voltage variable oscillator 300 has a plurality of thin film bulk acoustic wave resonators 42 connected in parallel.

  Each thin film bulk acoustic wave resonator 42 has the same configuration as that of the first to third examples described above. For example, the thin film bulk acoustic wave resonator 15 of FIG. 3 (the thin film bulk acoustic wave resonator of FIG. 131).

  The capacitive element is configured using the variable capacitive element 20 (for example, the MOS varactor 20 in FIG. 7, the varactor 19 in FIG. 8, etc.) as in the third example described above.

  As other configurations, the inverter 13 and the resistor 14 are the same as those of the thin film bulk acoustic wave oscillator 100 of FIG.

<Expansion of variable frequency range>
The reason why the variable frequency range can be expanded using the thin film bulk acoustic wave resonator 42 will be described.

FIG. 11 schematically shows an equivalent circuit of the thin film bulk acoustic wave resonator 42.
37 is a series resonant inductance _{L m.}
38 is a series resonant capacitance _{C m.}
39 is a series resonance resistance _{R m.}
Reference numeral 40 denotes a parallel resonance capacitance _CO .
41 is a parallel resonance resistance R _O.

  An equivalent circuit of the thin film bulk acoustic wave resonator 42 shown in FIG. 11 is called a modified Butterworth fan-Dyke model.

  In general, regarding the characteristics of the voltage variable oscillator, there are various demands depending on applications such as quick rise of oscillation, low power consumption, and resistance to pushing. Among these, the following two types of requirements are important.

  The first requirement is to increase the Q value of the thin film bulk acoustic wave resonator and provide high purity oscillation, although the variable frequency range may be narrow.

The Q value is expressed as Equation 1 when using the series resonance inductance L _m , the series resonance capacitance C _m , and the series resonance resistance R _m of the equivalent circuit.

In this case, to increase the reduced L _m the C _m within the range that can reduce the value of R _m is effective. Since C _m is proportional to the resonator area and the electromechanical coupling constant, it is not necessary to increase the area of the resonator.

  The second requirement is that the Q value of the thin film bulk acoustic wave resonator 42 does not need to be increased so much, but it is desired to expand the variable frequency range.

In this case, the resonance frequency f _r of the thin film bulk acoustic wave resonator 42, the effective electromechanical coupling constant K _eff ² , the parallel resonance capacitance C ₀ , the maximum capacitance C _Lmax and the minimum capacitance when two varactors are connected in series _. When _CLmin is used, the variable frequency Δf can be expressed approximately as shown in Equation 2.

From Equation 2, it can be understood that it is better to increase the effective electromechanical coupling constant K _eff ^2, to increase the maximum capacitance C _Lmax as much as possible, and to reduce the minimum capacitance C _Lmin as much as possible _. When the parallel resonant capacitance C ₀ is too small, since the small molecules variable frequency width is small, too large, the variable frequency range is reduced since the denominator is increased by C 0 _{/ (C} 0 * _{C 0),} C There is an optimum value for the _zero value.

FIG. 12 shows an example of the relationship between the value of the parallel resonant capacitance C ₀ and the variable frequency width Δf.

The C ₀ value that takes the maximum value of the variable frequency width is obtained by obtaining a value that becomes ₀ by partially differentiating Δf with C ₀ in Equation 2 to obtain 0.

The preferred C ₀ value range for the thin film bulk acoustic wave voltage variable oscillator 300 to obtain a wide tuning range is _1/7 of C _0max , which is a tuning range that is half the maximum tuning range on the low C ₀ side, and a high C value. _{The 0} value side is considered to be a range up to three times C _0max , which is a three-quarter tuning range of the maximum tuning range, taking into account the disadvantage that the area increases.

Although it is approximate because of the effect of the electrode, the area of the C ₀ value and the thin film bulk acoustic wave resonator 42 is in a proportional relationship as shown in Equation 4.

Where S is the area of the bulk acoustic wave resonance of the thin film, v _piezo is the bulk acoustic wave velocity in the piezoelectric thin film, ε _r is the relative dielectric constant of the piezoelectric material, ε ₀ is the dielectric constant of vacuum, and f _r is the resonant frequency. To express.

Laying maximum capacitance of _{C Lmax} of the variable capacitance of the oscillation circuit, and _{S min} of formula 5 obtained the minimum capacitance as _{C Lmin,} as within the range of _{S max} of Equation 6, the thin film bulk acoustic wave resonator 42 Thus, the thin film bulk acoustic wave voltage variable oscillator 300 having a wide tuning range can be obtained.

Although depending on the frequency to be oscillated and the piezoelectric material, a thin film bulk acoustic wave resonator having a large C ₀ is required to achieve a wide variable frequency.

  By expanding the area of the resonator, it is possible to produce such a resonator even in a circuit configuration composed of only one resonator, and it is considered as one of the options.

However, the C ₀ value was increased by fabricating a plurality of thin film bulk acoustic wave resonators 42 and connecting these resonators in parallel as in the circuit shown in FIG. 10 of this example. It is possible to obtain the equivalent effect.

  Therefore, by connecting a plurality of thin film bulk acoustic wave resonators 42 in parallel, the degree of freedom in layout can be improved, and options for realizing desired circuit fabrication can be diversified.

If the number of resonators in the circuit of FIG. 10 is the N, excluding the parasitic components, as compared with the case of a single resonator, the parallel resonant capacitance C ₀ is N times, the series resonant capacitance C _m is N times , the series resonant inductance _{L m} is to 1 / N times.

  The area of one resonator can be varied while maintaining the center frequency by connecting N resonators in parallel, even if the size is 1 / N of the resonator area defined in the range of Equations 5 and 6. A thin film bulk acoustic wave voltage variable oscillator 300 with an expanded frequency range can be manufactured.

  Such a circuit configuration is most suitable for a thin film bulk acoustic wave oscillator, regardless of whether a single resonator or a plurality of resonators are manufactured. Judging from the above, the circuit configuration divided into a plurality of resonators and connected in parallel is one of the characteristics of a thin film bulk acoustic wave oscillator different from the case of a resonator cut out from a crystal.

  Another feature of the circuit configuration in which a plurality of resonators are connected in parallel is also effective when the resonator is placed on the circuit portion as described in the first example.

  Mechanical vibrations from thin film bulk acoustic wave resonators and potential changes in the electrodes of the resonators may affect oscillation characteristics such as phase noise through capacitive coupling. There are few things to do, and it often exists in several parts.

  Even in such a case, it is an effective means for reducing the area of the chip by arranging the resonators divided into appropriate sizes at appropriate locations.

  For example, in the case of each circuit shown in FIGS. 3, 8, and 10, it is preferable to avoid a capacitance and a varactor that form a feedback loop together with the thin film bulk acoustic wave resonator.

[Sixth example]
A sixth embodiment of the present invention will be described with reference to FIGS. In addition, about the same part as each example mentioned above, the description is abbreviate | omitted and the same code | symbol is attached | subjected.

<Circuit example>
In this example, when a capacitive element is connected to each of two electrode portions of a thin film bulk acoustic wave resonator, the capacitance value or the number of elements of the other capacitive element is set to the capacitance value or the number of elements of the other capacitive element. This is an example of an asymmetric configuration.

  FIG. 13 shows an example of the circuit configuration of the thin film bulk acoustic wave oscillator 400.

The basic configuration of the thin film bulk acoustic wave oscillator 400 is the same as that of the circuit of FIG. 3 described above, and different parts will be described below.
Reference numeral 15 denotes a thin film bulk acoustic wave resonator (thin film bulk acoustic wave resonator 131 in FIG. 1).
Reference numeral 19 denotes a voltage variable capacitance element.
Reference numeral 44 denotes a parasitic capacitance component.

(Characteristics of asymmetric circuit)
Usually, increasing the voltage variable capacitance is an effective means for expanding the variable frequency range, but it cannot be said that the direction is generally preferable for an oscillator in a high frequency region.

  In the circuit configuration of FIG. 3 described above, the negative resistance (the real part of the complex impedance of the circuit including the inverter and the voltage variable capacitor) can be expressed as Equation 7.

  Here, gm is the mutual conductance of the transistor used in the inverter, C1 and C2 are the capacitance values of the voltage variable capacitive elements connected to the left end and the right end of the thin film bulk acoustic wave resonator, and r1 and r2 are the voltage variable capacitive elements, respectively. Represents parasitic resistance.

  When the negative resistance exceeds zero and becomes a positive resistance, oscillation does not occur. Further, even if the negative resistance value is negative, when it is lowered to several Ω, there are problems that it takes a long time for the oscillation to rise or that oscillation does not occur stably.

  As the frequency increases, the denominator of the fourth term of Equation 7 increases, and the transconductance of the transistor decreases, so the negative resistance value cannot maintain a large negative value and decreases.

  When the variable frequency range is expanded in the frequency range limited by the cutoff frequency of such a transistor, the oscillation frequency range is limited by the negative resistance value rather than the voltage variable capacitance element. By reducing the resistances r1 and r2 or by reducing C1 or C2, the upper limit of the oscillation frequency can be extended to the high frequency side, and the frequency variable range can be increased.

  When a plurality of voltage variable capacitance elements 19 are connected, the number of voltage variable capacitance elements connected to one electrode of the thin film bulk acoustic wave resonator 15 is reduced, or as shown in the example of FIG. If the voltage variable capacitance element 19 on the inverter input side is omitted, the parasitic resistance of the wiring portion on one side is eliminated, and the capacitance on the inverter input side is only the parasitic capacitance component.

  As a result, the value of C1 is significantly reduced, the negative resistance can be maintained at a high value up to a high frequency, and the oscillatable frequency range can be taken up to a high frequency. This is a configuration example in which the oscillation frequency can be expanded to a higher frequency by reducing the load capacity of the oscillator. In the frequency region where the gate resistance of the MOS transistor starts to affect, it is difficult to maintain a certain degree of oscillation margin while maintaining symmetry (both C1 and C2 load capacitances are kept small to maintain symmetry). Can be realized relatively easily. What confirmed the characteristic of such an asymmetric circuit by simulation is shown in FIG. 14 and FIG. 15 below.

  FIG. 14 shows the frequency dependence of the negative resistance obtained by simulation when 3 V is applied to the MOS type voltage variable capacitor connected to the thin film bulk acoustic wave resonator 15.

  FIG. 15 shows the frequency dependence of the negative resistance obtained by simulation when 0 V is applied to the MOS type voltage variable capacitor connected to the thin film bulk acoustic wave resonator 15.

  FIG. 14 and FIG. 15 show examples in which the inverter 13 is constituted by NMOS and PMOS transistors and the voltage variable capacitance element 19 is constituted by a MOS varactor in the circuit of FIG.

  A comparison is made between a case where a MOS varactor is connected to both ends of the thin film bulk resonator and a case where a MOS varactor is connected to only one side (output side).

  When the MOS varactor is omitted, only the parasitic capacitance of the MOS transistor remains. In this simulation, this parasitic capacitance is estimated to be about 1/30 of the minimum capacitance of the MOS varactor.

  14 shows a case where 3 V is applied to the MOS varactor, and FIG. 15 shows a case where 0 V is applied to the MOS varactor. The horizontal axis represents frequency (GHz) and the vertical axis represents the negative resistance (Ω) of the oscillator.

  A broken line 45 is a conventional example when a normal MOS varactor is connected to both ends of the resonator. A solid line 46 is an example of the present invention when a MOS varactor is connected to only one side.

  In the case of the former 45 of the conventional example, the negative resistance value decreases at a frequency exceeding 800 MHz, and stable oscillation becomes difficult. On the other hand, in the case of the latter 46 of the present invention, it can be seen that the negative resistance can be maintained up to about 2.5 GHz.

  Since the thin film bulk acoustic wave oscillator 400 can oscillate in a high frequency region of 1 GHz or more, it is possible to oscillate the negative resistance on the high frequency side as in the present invention without changing the process (minimum gate length). It is very useful when actually designing.

[Seventh example]
A seventh embodiment of the present invention will be described with reference to FIGS. In addition, about the same part as each example mentioned above, the description is abbreviate | omitted and the same code | symbol is attached | subjected.

  This example is an example for explaining a method of manufacturing the thin film bulk acoustic wave oscillators 100 to 400 described in the first to sixth examples.

<Outline of manufacturing method>
FIG. 16 shows an outline of a manufacturing method for manufacturing the thin film bulk acoustic wave oscillators 100 to 400 of the present invention.

  Here, description will be made using the thin film bulk acoustic wave oscillator 100 of FIG.

  In step S <b> 1, the circuit element unit 110 including the circuit element 111 including at least the transistor element 2 and the capacitor element 3 is formed on the substrate 1.

  In step S2, an acoustic having an acoustic mirror layer 121 formed by alternately stacking thin films 5a made of a high acoustic impedance material and thin films 5b made of a low acoustic impedance material on the circuit element unit 110. The mirror part 120 is formed.

  In step S3, thin film bulk elasticity comprising the piezoelectric thin film 7 and the two upper and lower electrodes 8 and 6 sandwiching the piezoelectric thin film 7 from above and below, immediately above the region where the acoustic mirror layer 121 of the acoustic mirror unit 120 is formed. A wave resonator 131 is formed, and the thin film bulk acoustic wave resonator 131 is acoustically separated from the circuit element 111 on the substrate 1 side via the acoustic mirror layer 121 to constitute the resonator unit 130.

  In step S4, the circuit element 111 of the circuit element unit 110 and the thin film bulk acoustic wave resonator 131 of the resonator unit 130 are electrically connected by wiring. In many cases, the capacitive element 3 is connected to at least one electrode 8 or 6 of the thin film bulk acoustic wave resonator 131.

  Thereby, the thin film bulk acoustic wave oscillator 100 of FIG. 1 can be produced.

<Production example>
Hereinafter, an example of manufacturing a thin film bulk acoustic wave oscillator using a microfabrication technique and a thin film formation technique will be described.

  FIG. 17 is a flowchart illustrating the manufacturing method of FIG. 16 in detail for each manufacturing process.

  18 to 21 are explanatory views showing a cross-sectional structure of the thin film bulk acoustic wave oscillator 100 corresponding to the manufacturing process of FIG. In this case, the manufacturing process may be a MOS process or a bipolar process. Here, an example of a MOS process will be described.

(Circuit element part)
The production of the circuit element unit 110 will be described.
The circuit element unit 110 is manufactured according to steps S10 to S20 in FIG.
In step S10 to step S12, an element isolation formation region is formed on the silicon substrate 1, and then a P well and an N well are formed.
In steps S13 to S14, a gate oxide film is formed, and a polysilicon gate is formed.
In steps S15 to S16, capacitance 3 and LDD are formed.
In steps S17 to S19, a source / drain diffusion layer is formed and silicidation is performed to form a wiring layer of the transistor 2.
In step S20, surface planarization on the wiring layer is performed.

  FIG. 18 is a cross-sectional view of the circuit element portion 110 when the surface is flattened.

27 is a metal wiring layer, 28 is an interlayer film of a silicon oxide film, and 28 is flattened by CMP (Chemical Mechanical Polishing).
When the thin film bulk acoustic wave resonator 131 is formed, since the flatness of the base is important, the sacrificial silicon oxide film thickness and the CMP polishing thickness are adjusted to achieve a flatness of about 0.1 to 0.2 μm. It is desirable.

(Acoustic mirror part)
The production of the acoustic mirror unit 120 will be described.

The acoustic mirror unit 120 is manufactured according to steps S21 to S22 in FIG.
In step S21, the acoustic mirror layer 121 is formed.
In step S22, surface flattening on the acoustic mirror layer 121 is performed.

  FIG. 19 is a cross-sectional view when the acoustic mirror layer 121 is formed.

  29 represents a thin film (5a) composed of a high acoustic impedance material, and 30 represents a thin film (5b) composed of a low acoustic impedance material. Both have acoustic wave velocities specific to the material, but each layer is formed with a thickness of about ¼ wavelength of the center frequency.

  By alternately stacking the thin film 29 made of the high acoustic impedance material and the thin film 30 made of the low acoustic impedance material, it is possible to efficiently reflect an acoustic wave in a specific frequency band.

  At present, a silicon oxide film is most suitable for the thin film 30 made of a low acoustic impedance material. There are several candidates for the thin film 29 made of a high acoustic impedance material, and a material having a high density such as tungsten, aluminum nitride, or tantalum oxide is suitable.

  The high acoustic impedance layer may be formed on the entire surface of the wafer except for the contact portion, or may be formed while forming a pattern by etching.

  In the example of FIG. 19, the acoustic mirror layer 121 is formed only in a portion where the resonator is formed so as not to interfere with the connection between the resonator and the oscillation circuit.

  In this example, the acoustic mirror layer 121 is formed after planarization, but it is also effective to perform planarization immediately before the formation of the lower electrode 6 in addition to that.

(Resonator part)
The production of the resonator unit 130 will be described.
The resonator unit 130 is manufactured according to steps S23 to S27 in FIG.
In step S23, the lower electrode 6 is formed.
In step S24, the pattern of the lower electrode 6 is formed.
In step S25, the piezoelectric thin film 7 is formed.
In step S26, the upper electrode 8 is formed.
In step S27, the pattern of the upper electrode 8 and the piezoelectric thin film 7 is formed.

  FIG. 20 is a cross-sectional view when the piezoelectric layer is formed.

  Reference numeral 31 denotes a lower electrode, and 32 denotes a piezoelectric thin film. As described above, platinum, molybdenum, aluminum, ruthenium, tungsten, or the like can be used for the lower electrode 31. After depositing on the entire surface of the wafer using a thin film deposition method such as sputtering, a pattern is formed using a lithography technique.

  The lower electrode 31 serves as a base for forming the piezoelectric thin film 32 and greatly affects the quality of the piezoelectric thin film 32. Therefore, it is necessary to select appropriate materials and conditions. When the piezoelectric thin film 32 is made of aluminum nitride, it is crystallized in the c-axis direction by a reactive plasma sputtering method in which an aluminum target is sputtered and simultaneously activated by introducing nitrogen into the plasma and reacting both on the wafer. Therefore, it is possible to grow an aluminum nitride thin film with good characteristics.

(Wiring section)
The production of the wiring portion will be described.

  The wiring portion is manufactured according to step S28 in FIG.

  In step S28, wiring between the transistor part of the circuit element part 110 and the resonator part 130 is performed.

  FIG. 21 is a cross-sectional view of a wiring process connecting the resonator unit 130 and the transistor unit.

  33 is an upper electrode. After the piezoelectric thin film 32 is formed, the upper electrode 33 is formed thereon.

  The material is preferably aluminum or an aluminum alloy containing an additive for improving electromigration resistance, but molybdenum or the like can also be used. After forming the upper electrode 33, pattern formation is performed using a lithography technique.

  In the example of FIG. 21, the piezoelectric thin film 32 is etched at this timing, and the silicon oxide film is etched to open a hole for connection to the metal wiring layer. After the upper electrode 33 of the resonator unit 130 is covered with the protective layer 34, a thick aluminum wiring layer 35 is deposited on the entire surface.

  Next, after protecting the portion left by the photoresist 36, the wiring unnecessary portion is removed by etching. Thereby, wiring between the resonator and the transistor circuit is finally formed, and the protective layer 34 is removed.

  Through the above steps, the resonator unit 130 is formed on the same substrate 1 as the circuit element unit 110 including the transistor unit, and the circuit element such as the active element can be operated by wiring connection therebetween.

[Eighth Example]
An eighth embodiment of the present invention will be described with reference to FIG. In addition, about the same part as each example mentioned above, the description is abbreviate | omitted and the same code | symbol is attached | subjected.

  This example is an example in the case where a plurality of thin film bulk acoustic wave resonators are formed and each of the thin film bulk acoustic wave resonators has a different resonance frequency.

  The first to seventh examples described above have described the case where the resonance frequencies of the plurality of resonators (thin film bulk acoustic wave resonator 131) are the same.

  However, as shown in FIG. 22, a step of forming a member 43 for causing a resonance frequency shift on the upper electrode 33, for example, a silicon oxide film, and a material selectively using a photoresist 36. By adding an etching step, a resonator with a shifted resonance frequency can be obtained.

  In this way, it is possible to configure an oscillator having a wide band by connecting resonators having different resonance frequencies to a selection switch including transistors and switching or combining them in a circuit.

  In addition to the above examples, a plurality of resonators can be used for other purposes. Even in that case, it is possible to reduce the size by devising the arrangement of the elements.

[Ninth example]
A ninth embodiment of the present invention will be described. In addition, about the same part as each example mentioned above, the description is abbreviate | omitted and the same code | symbol is attached | subjected.

  This example is an example in which the thin film bulk acoustic wave oscillators of the first to eighth examples described above are configured as part of an integrated circuit on a semiconductor substrate.

  In the first to eighth examples, the thin film bulk acoustic wave oscillator 100 and the thin film bulk acoustic wave voltage variable oscillators 200, 300, and 400 have been described. However, these circuits are not limited to other semiconductor integrated circuits. In some cases, it is preferable to be manufactured integrally with other semiconductor integrated circuits.

  The methods described in the seventh and eighth examples described above are not limited to the thin film bulk acoustic wave oscillator 100 and the thin film bulk acoustic wave voltage variable oscillators 200, 300, and 400, but a thin film bulk as a part thereof. The same applies to the semiconductor integrated circuit including the acoustic wave oscillator 100 and the thin film bulk acoustic wave voltage variable oscillators 200, 300, and 400.

It is sectional drawing which shows one example of the structure of the thin film bulk acoustic wave oscillator which is the 1st Embodiment of this invention. It is a top view which shows an example of the layout which spaced apart the thin film bulk acoustic wave resonator and the capacitive element for frequency adjustment. It is a circuit diagram which shows one example of the circuit structure of a thin film bulk acoustic wave oscillator. It is explanatory drawing which shows one example of the frequency characteristic of the admittance of a thin film bulk acoustic wave resonator. It is sectional drawing which shows one example of the structure of the thin film bulk acoustic wave oscillator which is the 2nd Embodiment of this invention. It is a top view which shows an example of the layout which has arrange | positioned the thin film bulk acoustic wave resonator divided | segmented into plurality on another element. It is sectional drawing which shows one example of the structure of the thin film bulk acoustic wave voltage variable oscillator which is the 3rd Embodiment of this invention. It is a circuit diagram which shows one example of the circuit structure of a thin film bulk elastic wave voltage variable oscillator. It is sectional drawing which shows one example of the structure of the thin film bulk acoustic wave voltage variable oscillator which is the 4th Embodiment of this invention. It is a circuit diagram which shows an example of the circuit structure of the thin film bulk acoustic wave oscillator connected in parallel which is the 5th Embodiment of this invention. It is a circuit diagram which shows the equivalent circuit of a thin film bulk acoustic wave. It is explanatory drawing which shows one example of the relationship between a variable frequency range and a parallel resonance capacitance. It is a circuit diagram which shows one example of the thin film bulk acoustic wave oscillator which excluded the voltage variable capacitance element of the one side of the thin film bulk acoustic wave resonator which is the 6th Embodiment of this invention. It is explanatory drawing which shows the frequency dependence of the negative resistance calculated | required by simulation, when 3V is applied to the MOS type voltage variable capacitance element connected to a thin film bulk acoustic wave resonator. It is explanatory drawing which shows the frequency dependence of the negative resistance calculated | required by simulation, when 0V is applied to the MOS type voltage variable capacitance element connected to a thin film bulk acoustic wave resonator. It is a flowchart which shows the outline of the manufacturing method of the thin film bulk acoustic wave oscillator which is the 7th Embodiment of this invention. It is a flowchart which shows the manufacturing process of a thin film bulk acoustic wave oscillator. It is sectional drawing which shows the manufacturing process at the time of the surface planarization of a circuit element part. It is sectional drawing which shows the manufacturing process at the time of acoustic mirror formation. It is sectional drawing which shows the manufacturing process at the time of piezoelectric material layer formation. It is sectional drawing which shows the manufacturing process at the time of a wiring process. It is sectional drawing which shows one example of the manufacturing process for shifting the resonant frequency which is the 8th Embodiment of this invention.

Explanation of symbols

1 Silicon substrate 2 Transistor part (MOS transistor)
DESCRIPTION OF SYMBOLS 3 Capacitance part 4 Metal wiring layer between transistors 5a Thin film comprised with high acoustic impedance material 5b Thin film comprised with low acoustic impedance material 6 Lower electrode 7 Piezoelectric thin film 8 Upper electrode 9 Resonator-transistor metal wiring layer 10 n + Buried layer 11 Epi-grown layer 12 Transistor part (bipolar transistor)
13 Inverter amplifier circuit (negative resistance part)
DESCRIPTION OF SYMBOLS 14 Resistance 15 Thin film bulk acoustic wave resonator 16 Capacitance 17 Resonance point 18 Antiresonance point 19 Voltage variable capacity element 20 Voltage variable capacity element (MOS varactor)
DESCRIPTION OF SYMBOLS 21 Thin film bulk acoustic wave resonator 22 Inverter transistor area 23 Capacitance 24 Polysilicon resistance 25 Peripheral circuit, such as an output driver 26 Power supply / GND / Output pad and electrostatic breakdown prevention circuit 27 Metal wiring layer 28 Silicon oxide interlayer 29 High acoustic Impedance layer 30 Low acoustic impedance layer 31 Lower electrode 32 Piezoelectric thin film 33 Upper electrode 34 Upper electrode protective layer 35 Resonator-transistor wiring layer 36 Photoresist
37 Series Resonance Inductance 38 Series Resonance Capacitance 39 Series Resonance Resistance 40 Parallel Resonance Capacitance 41 Parallel Resonance Resistance 42 Parallel Connection of Multiple Thin Film Bulk Acoustic Wave Resonators 43 Film Added to Shift Resonance Frequency 44 Parasitic Capacitance Component 45 On Both Sides Characteristic curve when MOS varactor is connected (broken line)
46 Characteristic curve when MOS varactor is connected to only one side (solid line)
DESCRIPTION OF SYMBOLS 100 Thin film bulk acoustic wave oscillator 110 Circuit element part 111 Circuit element 120 Acoustic mirror part 121 Acoustic mirror layer 130 Resonator part 131 Thin film bulk acoustic wave resonator 200,300,400 Thin film bulk acoustic wave voltage variable oscillator

Claims (15)

A thin film bulk acoustic wave oscillator,
A circuit element portion in which a circuit element including at least a transistor element and a capacitor element is formed on a substrate;
On the upper part of the circuit element part, an acoustic mirror part in which an acoustic mirror layer is formed by alternately stacking a thin film made of a high acoustic impedance material and a thin film made of a low acoustic impedance material,
A thin film bulk acoustic wave resonator comprising a piezoelectric thin film and two electrode portions sandwiching the piezoelectric thin film from above and below is formed immediately above the region where the acoustic mirror layer of the acoustic mirror portion is formed, and The thin film bulk acoustic wave resonator includes a resonator unit configured to be acoustically separated from the substrate and the circuit element on the substrate side via the acoustic mirror layer,
A thin film bulk acoustic wave oscillator, wherein the circuit element of the circuit element section and the thin film bulk acoustic wave resonator of the resonance section are electrically connected by wiring.   2. The thin film bulk acoustic wave oscillator according to claim 1, wherein the capacitive element comprises a fixed capacitive element or a variable capacitive element for setting an oscillation frequency of the thin film bulk acoustic wave resonator to a predetermined value. 3. The thin film bulk acoustic wave oscillator according to claim 1, wherein the piezoelectric thin film is made of aluminum nitride. Said circuit element is a silicon MOS transistor, a silicon bipolar transistor, or claims 1 to film bulk acoustic wave oscillator according to any one of 3, characterized in that it consists of silicon germanium transistors. The wiring connection distance between the thin film bulk acoustic wave resonator and the capacitive element is set to be longer than the wiring connection distance between the thin film bulk acoustic wave resonator and the transistor element. The thin film bulk acoustic wave oscillator according to any one of claims 1 to 4 . Wherein using a plurality of thin film bulk acoustic wave resonator according to claim 1 to a film bulk acoustic wave oscillator according to any one of 5, characterized in that connecting the respective film bulk acoustic wave resonators in parallel. Changes in mechanical vibration and capacitive coupling due to the thin film bulk acoustic wave resonators do not affect the oscillation frequency characteristics, and the thin film bulk acoustic wave resonators are disposed immediately above the circuit elements. 6. Symbol mounting of the thin film bulk acoustic wave oscillator and said. When the capacitive element is connected to the two electrode portions of the thin film bulk acoustic wave resonator, the capacitance value or the number of elements of the other capacitive element is asymmetric with respect to the capacitance value or the number of elements of one capacitive element. claims 1, characterized in that the to film bulk acoustic wave oscillator according to any one of 7. In the case where the thin film bulk acoustic wave resonators comprising a plurality thin film bulk acoustic according to any one of claims 1 to 8, characterized in that respective film bulk acoustic wave resonators have different resonance frequencies from each other Wave oscillator. Wherein at least one of the electrodes of the thin film bulk acoustic wave resonator according to claim 1 to a film bulk acoustic wave oscillator according to any one of 9, characterized in that connecting the capacitive element. As part of an integrated circuit on a semiconductor substrate, a semiconductor integrated circuit, characterized in that it constitutes a film bulk acoustic wave oscillator according to claim 1 to 10 SL placement. A manufacturing method for manufacturing a thin film bulk acoustic wave oscillator using microfabrication technology and thin film formation technology,
Forming a circuit element portion including a circuit element including at least a transistor element and a capacitor element on a substrate;
Forming an acoustic mirror portion having an acoustic mirror layer formed by alternately stacking thin films made of a high acoustic impedance material and thin films made of a low acoustic impedance material on the circuit element portion; ,
A thin film bulk acoustic wave resonator including a piezoelectric thin film and two electrode portions sandwiching the piezoelectric thin film from above and below is formed immediately above the region where the acoustic mirror layer of the acoustic mirror portion is formed, Forming a resonator unit by acoustically separating a thin film bulk acoustic wave resonator from the substrate and the circuit element on the substrate side via the acoustic mirror layer; and
A method of manufacturing a thin film bulk acoustic wave oscillator, comprising the step of electrically connecting the circuit element of the circuit element section and the thin film bulk acoustic wave resonator of the resonator section. The capacitive element, said for setting the oscillation frequency of the film bulk acoustic wave resonator to a predetermined value, the thin film bulk acoustic wave oscillator according to claim 12 Symbol mounting characterized by comprising the fixed capacitance element or variable capacitance element Production method. The piezoelectric thin film, according to claim 12 or 13 Symbol mounting method of manufacturing a film bulk acoustic wave oscillator, characterized in that it consists of aluminum nitride. 15. The method of manufacturing a thin film bulk acoustic wave oscillator according to claim 12 , wherein the circuit element comprises a silicon MOS transistor, a silicon bipolar transistor, or a silicon germanium transistor.

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