JP2008107336A - Production method of sensor and production method of resonator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method of sensors and the like capable of achieving high productivity. <P>SOLUTION: In production of sensors which are equipped with a disk-like vibrator, a driving electrode and a detecting electrode arranged at a circumference of the vibrator on the other side of gap, the production method of the sensors is designed to include a first pattern forming process implementing pattern formation on the vibrator and the gap section between the driving electrode and the detecting electrode by irradiating electron beam and also a second pattern forming process implementing pattern formation on the vibrator and the section other than gap section between the driving electrode and a detecting electrode by a stepper. An alignment mark M for performing pattern formation by irradiating electron beam is formed so as not to penetrate an active Si layer 53 to prevent charge-up in a box layer 52. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a sensor suitable for use in detecting the presence or absence of a substance having mass, detecting the mass of a substance, and the like.

Advances in micromachining technology such as micromachine / MEMS (Micro Electro Mechanical Systems) technology have made it possible to make mechanical vibrators extremely small. As a result, the mass of the vibrator itself can be made small, so even if the mass changes due to the adhesion of extremely small substances (such as molecules or viruses) at the molecular level, the frequency and impedance characteristics fluctuate. Highly sensitive vibrators are being realized. By using such a highly sensitive vibrator, it is possible to configure a sensor or the like that can detect the presence or amount of a very small substance.
An apparatus that detects the amount of a substance by changing the frequency of a mechanical vibrator is well known as a QCM (Quarts Crystal Micro balance) sensor. This utilizes the property that when a substance adheres to the crystal unit, the vibration frequency varies (decreases) depending on the mass of the substance, and has excellent performance as a mass sensor that measures minute masses. In addition, it is often used as a film thickness meter (evaporation monitor).
Such a vibrator is greatly reduced in size, so that the frequency of the vibrator is increased to the GHz level, and Si can be used as a material. The research is developing.

  In addition, high-frequency filters that are actively used in personal wireless communication devices such as mobile phones are mainly dielectric resonators designed to reduce the size and performance of electrical resonators, and surface-wave filters that use the characteristics of sound waves. (SAW Filter) and a quartz filter (Quarts Crystal Filter) that uses the mechanical vibration characteristics of a crystal resonator, and are widely used in high-frequency parts of mobile phones, etc., taking advantage of each characteristic. However, because there is a strong demand for lower prices as well as higher performance such as further miniaturization and higher frequency of wireless devices, it is replaced with these conventional filters and integrated with semiconductor integrated circuits, that is, one-chip There is a need for a new high-frequency filter that can be made smaller and less expensive. A mechanical vibrator created by the MEMS processing technique is a promising candidate because the material is Si, which is the same as that of a semiconductor. Therefore, basic research aimed at increasing the frequency and high quality factor (Q) of MEMS vibrators and applying research to high-frequency filters and transmitters using this MEMS vibrator are also active. (For example, refer nonpatent literature 1.).

  One type of such a vibrator is a disk-shaped vibrator. Basic research on the mechanical vibration of disk-shaped vibrators has been conducted for a long time, and basic research on vibration modes (vibration modes) that define the vibration state of disk-shaped vibrators has already been completed. You can say that.

  However, in the sensor and the filter using the vibrator whose vibration characteristics are changed by adhesion of a minute mass as described above, further higher sensitivity, smaller size, and lower price are always required. Therefore, as a research subject associated with MEMS of disk-shaped vibrators, characteristics control by combining vibrators for the purpose of improving Q value for high sensitivity, driving and detecting methods of vibrators, and applying to filters Etc., and intensive research has been conducted on these.

C. T.-C. Nguyen, “Vibrating RF MEMS Technology: Fuel for an Integrated Microchemical Circuit Revolution ?.” The 13th International Conference on Solid-State Sensors, Actuators and Microsystems (Transducers `05), Korea, June 5-9, 2005

  An ultra-small vibrator formed by MEMS processing can be miniaturized and is often driven and detected via a capacitance between electrodes that can be detected with high accuracy. In this case, driving is often performed by the electrostatic force of the vibrator and the drive electrode, and detection is often performed by changing the capacitance between the vibrator and the detection electrode. Here, if the gap between the vibrator, the drive electrode, and the detection electrode is large, the capability of driving and detection becomes small. If the gap is made small, it is possible to detect a change in vibration of the vibrator with high sensitivity. Furthermore, the smaller the gap, the more the power can be driven by the vibrator, so energy saving can be achieved. When this vibrator is used in a portable device, the power source can be made smaller and smaller. Since the capacity can be increased, the size of the device can be reduced. Thus, it is preferable that the gap between the vibrator and the electrode is small.

Conventionally, a vibrator and an electrode disposed in the vicinity of the vibrator are generally formed on a substrate by a stepper for manufacturing a semiconductor element.
In the pattern formation technique using an exposure apparatus such as a MEMS stepper or contact aligner, it is possible to form a fine pattern of about 1 μm or less, but such an exposure apparatus is very expensive. High, and greatly affects the manufacturing cost of the vibrator.
On the other hand, in recent years, EB (Electron Beam) irradiation technology is being used to form fine patterns. In the case of the EB irradiation technique, pattern formation is performed by irradiating EB generated from an EB generation source. Therefore, the gap between the vibrator and the electrode can be expected to be reduced to about the beam diameter. However, in pattern formation by EB irradiation, the pattern formation object and the EB are moved relative to each other so that the surface of the pattern formation object is scanned and EB is drawn in a linear shape. It takes an enormous amount of time to form the pattern, which is unrealistic in terms of productivity.
The present invention has been made to solve the technical problems as described above. The gap between the vibrator and the electrode is reduced, the detection sensitivity of the vibrator is increased, the drive power is saved, and the vibrator device. It is an object of the present invention to provide a sensor manufacturing method and the like that can reduce the size of the sensor and achieve high productivity at low cost.

The inventors of the present invention have considered using a combination of pattern formation by EB and pattern formation by a stepper in the course of intensive studies to solve the above-described problems. We thought that productivity could be improved by patterning other portions using a stepper while minimizing the gap between the vibrator and the electrode by EB.
That is, the present invention is a method for manufacturing a sensor including a vibrator and an electrode that is disposed on the outer periphery of the vibrator with a gap therebetween and detects vibration of the vibrator or a change in vibration of the vibrator. Then, in the substrate material constituting the sensor, the first pattern forming step of patterning the gap portion between the vibrator and the electrode by electron beam irradiation, and the portion other than the gap portion between the vibrator and the electrode And a second pattern forming step of forming a pattern by exposing light having a longer wavelength than that. Here, pattern formation by exposing light having a wavelength longer than that of an electron beam is a pattern formation by a stepper that performs batch exposure of light in a predetermined wavelength region using a mask, or a reduced exposure apparatus and a 1: 1 exposure apparatus. It is. Such a stepper or the like does not require a high resolution level like a MEMS stepper or a contact aligner, and can reduce the cost of the apparatus.

Thus, it has been found that there are various problems when trying to combine pattern formation by so-called line drawing in EB and pattern formation by batch exposure in a stepper or the like.
First, in both cases of EB and stepper, when forming a pattern, an alignment mark is formed on the substrate material, and after performing alignment with the alignment mark as a reference, the pattern is formed.
In the case of a stepper, when forming a pattern on a substrate material, an alignment mark is formed on the surface of the substrate material, and then a resist film is formed on the surface of the substrate material for pattern formation. However, when pattern formation is performed in EB, when alignment is performed using an alignment mark formed on the surface of the substrate material, it is made of a dielectric material such as a resist material or a box layer made of Si oxide constituting the substrate material. If the layer is exposed, the charge generated in the EB pattern forming apparatus is charged to the dielectric layer. Then, the field of view of the alignment system of the EB pattern forming apparatus is hindered, the alignment mark is difficult to recognize, and alignment is difficult.
That is, if the pattern formation by EB and the pattern formation by the stepper are simply combined, the overlay accuracy of the pattern formed by the EB and the pattern formed by the stepper cannot be guaranteed.

Therefore, in the present invention, a substrate composed of a base support substrate, a box layer made of Si oxide formed on the support substrate, and an Si layer formed on the box layer and forming a vibrator. The method further includes the step of forming an alignment mark for aligning the substrate material on the plate material in the first pattern forming step and the second pattern forming step. In the step of forming the alignment mark, it is preferable that at least the alignment mark used in the first pattern forming step is formed on the Si layer so as not to reach the box layer.
In this way, since the alignment mark does not reach the box layer but remains in the Si layer, the EB pattern forming apparatus prevents the charge from being charged to the resist material or the box layer made of a dielectric material. It becomes possible to perform alignment reliably. The alignment marks can be provided separately for EB pattern formation and for pattern formation with a stepper. In that case, by forming both at the same time in the process of forming the alignment mark, it is possible to ensure the accuracy of the alignment reference when forming the pattern by EB and when forming the pattern by the stepper.

  In the first pattern formation step, it is preferable to remove the oxide film formed on the surface of the substrate material prior to pattern formation by electron beam irradiation. Thereby, it can prevent that a crack etc. arise around the pattern formed by electron beam irradiation.

  By the way, when the pattern formed by electron beam irradiation and the pattern formed by photolithography are overlapped in this way, in the first pattern forming step, the width of the pattern formed by electron beam irradiation is set to the second pattern. It is preferable to form a portion wider than other portions in the portion where the pattern to be formed in the formation step is overlapped. Thereby, it is possible to absorb an error in overlaying the pattern formed by electron beam irradiation and the pattern formed by the stepper.

In addition, in order to connect the wiring from the power source and the wiring to the detection circuit to the electrode arranged in the vicinity of the vibrator, a wiring pattern is formed on the substrate from the electrode to the wiring connection portion. A conductive metal is deposited on the substrate by sputtering or the like. At this time, if a fine gap is formed by EB first, even if it is attempted to remove the conductive metal after sputtering or the like, the conductive metal that has entered the fine gap is removed in the subsequent pattern formation or etching process. It may be difficult to remove completely.
Therefore, in the second pattern formation step, when the connection electrode that is electrically connected to the electrode and connected to the external power supply or detection circuit and the ground electrode are formed on the support substrate, the substrate material is subjected to the first pattern formation step. After applying the resist material to the range including the formed pattern portion, the resist material at the connection electrode and ground electrode portions is removed, and the metal constituting the connection electrode and the ground electrode is deposited or sputtered, and then the resist material Is preferably removed. In this way, by covering the portion of the pattern formed by the electron beam with the resist material, the conductive metal is sputtered onto the resist material in the portion of the minute gap. If removed, the conductive metal can be reliably removed, and the above-described problems can be avoided.

  By the way, the sensor of the present invention can be used as a mass sensor or the like for detecting the amount of a substance attached to the vibrator. In such a sensor, the substance to be detected can be a specific molecule or a plurality of types of molecules having specific characteristics or characteristics. Thereby, this sensor can be used for a gas detection sensor, an odor sensor, etc., for example. For this purpose, when a gas, a biological molecule, a living space floating molecule, a volatile molecule, or the like is targeted as a specific molecule, it is desirable to detect only a specific type of molecule with high selectivity. In addition, by using a plurality of such highly selective sensors, a plurality of types of molecules can be recognized, and the application range of applications can be expanded. It is also possible to detect a group of molecules having specific characteristics or a group of molecules having the same side chain, which is called global recognition. In this case, a plurality of sensors may be used, and molecular groups may be recognized by signal processing, processing using software, or the like based on the difference in detection ability between the plurality of sensors. In addition, a specific protein, enzyme, sugar chain, or the like may be detected by changing the configuration to operate in a liquid.

The detection of minute mass can be used for film thickness monitoring during thin film formation, detection of biomolecules such as antibody-antigen reaction and protein adsorption, and bioresearch. The sensor of the present invention is suitable for such applications.
In addition, the sensor and vibrator of the present invention are used for small and stable high-sensitivity home and personal gas sensors, and for use in the detection of harmful substances floating in the air, etc. with a disposable portable type excellent in portability. It is also possible. If the sensitivity is further increased, the range of application will be further expanded and it can be developed until “smell” can be detected and identified. Furthermore, the sensor of the present invention can be used for other purposes. It does not prevent it.

The present invention is not limited to the sensor, and can also be applied to the case of manufacturing a resonator used in a high-frequency circuit, a filter, or the like.
In this case, a method for manufacturing a resonator is a method for manufacturing a resonator including a vibrator and an electrode disposed on the outer periphery of the vibrator with a gap therebetween. In the substrate material composed of the formed Si oxide box layer and the Si layer that is formed on the box layer and forms the vibrator, the gap portion between the vibrator and the electrode is patterned by electron beam irradiation. And a second pattern forming step of patterning a portion other than the gap portion between the vibrator and the electrode by exposing light having a wavelength longer than that of the electron beam, Prior to the first pattern formation process, the alignment mark is formed on the Si layer so as not to reach the box layer. In the first pattern formation process and the second pattern formation process, an alignment mark is formed. It aligns the substrate material using a placement marks, and performs pattern formation.

  According to the present invention, the pattern formation by EB can reduce the gap between the vibrator and the electrode to increase the detection sensitivity of the vibrator, reduce the drive power energy, and reduce the size of the vibrator device. it can. Moreover, high productivity can be realized at low cost by performing pattern formation with a stepper or the like except for a portion where a fine pattern needs to be formed.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
FIG. 1 is a diagram for explaining a basic configuration of a sensor 10 according to the present embodiment.
The sensor 10 shown in FIG. 1 includes a vibrator 20 whose vibration frequency changes when a detection object such as a molecule having mass is attached, a drive source 30 for vibrating the vibrator 20, and vibration in the vibrator 20. And a detection unit 40 that detects a change in characteristics.

The vibrator 20 has, for example, a disk shape and has a circular shape, a rectangular shape, or another shape (circular shape in the example of FIG. 1) as a whole, and is supported only by the support member 22 connected to a predetermined position on the outer peripheral portion. All remaining parts are in a free state.
A driving unit 30 for driving (vibrating) the vibrator 20 and a detecting unit 40 for detecting a change in vibration of the vibrator 20 are disposed on the outer periphery of the vibrator 20. That is, the drive electrode (electrode) 30a and the detection electrode (electrode) 40a are disposed so as to face the vibrator 20 with a predetermined gap. The drive electrode 30a and the detection electrode 40a are formed such that their tip portions continue along the outer peripheral portion of the vibrator 20 for a certain length.

A current generated by an external controller (not shown) is supplied from the connection electrode 30b to the drive electrode 30a, whereby the drive electrode 30a vibrates the vibrator 20 using an electrostatic effect or a piezoelectric effect (piezoelectric effect).
Similarly, the detection electrode 40a detects vibration in the vibrator 20 from the connection electrode 40b by an electrostatic effect or a piezo effect generated between the detection electrode 40a and the vibrator 20, and outputs it as an electric signal. Yes. At this time, if a substance having a mass adheres to the vibrator 20, the vibration frequency of the vibrator 20 changes under the influence of the mass. In the external detection device (detection circuit), by monitoring the electrical vibration output from the connection electrode 40b, whether or not the substance is attached to the vibrator 20 or the amount of the substance attached to the vibrator 20 is determined. It is possible to detect.
The drive unit 30 composed of the drive electrode 30a and the connection electrode 30b and the detection unit 40 composed of the detection electrode 40a and the connection electrode 40b are structurally the same, and the connection of the detection device to the connection electrodes 30b and 40b is performed. By replacing it, its role can be changed.

In such a sensor 10, as shown in FIG. 2A, a box layer 52 made of SiO ₂ (Si oxide) and an active Si layer (Si layer) 53 are stacked on a Si support substrate 51. This is realized by forming a predetermined pattern on the substrate material 50 configured as described above. Here, in the present embodiment, the thickness of the support substrate 51 is 400 μm, the thickness of the box layer 52 is 1 μm, and the thickness of the active Si layer 53 is 2 μm.
Hereinafter, a method for realizing the sensor 10 by forming a pattern on the substrate material 50 will be described.

First, as shown in FIG. 2B, a resist material is applied to the surface of the substrate material 50 on the active Si layer 53 side (hereinafter referred to as “front surface” and the surface on the support substrate 51 side is referred to as “back surface”). Apply R1.
Next, using a mask for forming alignment marks for patterning by EB and patterning by a stepper, exposure is performed by a stepper apparatus, followed by development. Thereby, the resist material R1 is removed only in the portion P1 where the alignment mark is to be formed.

  Subsequently, as shown in FIG. 2C, etching is performed by a D-RIE (Deep Reactive Ion Etching) method. Thereby, the portion P <b> 1 that forms the alignment mark is etched, and the alignment mark M is formed in the active Si layer 53. At this time, in the etching by the D-RIE method, the thickness of the active Si layer 53 is set so that the active Si layer 53 having a thickness of 2 μm does not penetrate the active Si layer 53 and reach the box layer 52. Etching to a small depth, for example, 1 μm.

FIG. 3 is an example of an alignment mark M for patterning by EB. If the alignment mark M is formed through the active Si layer 53, the box layer 52 is exposed. Since the box layer 52 is a dielectric, the resist material R1 and the box layer 52 may be charged up when the alignment mark M is checked when forming the pattern with the EB pattern forming apparatus. It is expected that M will be difficult to see. 4A and 4B show a state where the resist material R1 is charged up. Therefore, the etching by the D-RIE method is limited to 1 μm, for example, so as not to penetrate the active Si layer 53, thereby confirming the alignment mark M as shown in the two-dot chain line in FIG. Make it easy.
4A shows a state in which the alignment mark M is visually recognized by the alignment system of the EB pattern forming apparatus when the alignment mark M is formed through the active Si layer 53. FIG. FIG. 4B is an enlarged view of the dotted line range of FIG. 4A, and FIG. 4C shows the case where the alignment mark M is formed so as not to penetrate the active Si layer 53, and FIG. In the same range, the alignment mark M is visually recognized by the alignment system of the EB pattern forming apparatus.

Next, as shown in FIG. 5A, after removing the resist material R1 with acetone or IPA (isopropyl alcohol), O ₂ ashing is further performed, and the resist remaining on the front and back surfaces of the substrate material 50 is obtained. The material R1 is removed.
After removing the resist material R1, the natural oxide film formed on the surface of the active Si layer 53 is removed with a BHF solution (NH ₄ F / HF / H ₂ O).
If there is a natural oxide film on the surface of the active Si layer 53, when a pattern is formed by EB later, cracks or the like starting from the pattern may occur, and this is prevented by removing the natural oxide film.

Subsequently, as illustrated in FIG. 5B, a resist material R <b> 2 used for pattern formation by EB is applied to the surface of the active Si layer 53.
Then, the periphery of the previously formed alignment mark M is exposed and developed. Thereby, the resist material R2 covering the alignment mark M can be removed.
In this state, the alignment mark M is used to perform alignment (positioning) of the substrate material 50 in the EB pattern forming apparatus.

After that, as shown in FIG. 5C, in the EB pattern forming apparatus, the substrate material 50 is irradiated with EB and scanned along a predetermined locus. At this time, for example, the dose and the scan speed of EB can be adjusted, so that the pattern P2 having a line width of 100 nm can be exposed to the resist material R2.
At this time, as shown in FIG. 6, the slit-shaped pattern P2 formed by EB irradiation is formed thick in the overlapping portion X with the pattern formation by the stepper to be performed later. This is for compensating the alignment accuracy between the pattern Ps formed by the stepper and the pattern P2 formed by the EB. That is, if the pattern P2 is within a thick range in the overlapped portion X, the pattern Ps formed by the stepper is as shown in (b) with respect to the designed position shown in (a) in FIG. Even if they are misaligned, the vibrator 20 and the electrode can be reliably divided. The dimension for thickening the slit-shaped pattern P2 formed by EB irradiation is determined within a range that allows an alignment error, and is, for example, about 1 to 2 μm.
When the resist material R2 is developed, only the portion irradiated with EB is removed from the resist material R2, and a slit-like pattern P2 having a line width of 100 nm is formed on the resist material R2.

  Subsequently, as shown in FIG. 7A, a portion of the slit-like pattern P2 having a line width of 100 nm formed on the resist material R2 is formed by a D-RIE method at a depth corresponding to the thickness of the active Si layer 53. Etching is performed (2 μm in this embodiment). As a result, a slit 200 having a line width of 100 nm penetrating the active Si layer 53 is formed. Here, the D-RIE method is used to form the slit 200, but other methods may be used depending on the width and depth of the slit 200, the aspect ratio (width / depth of the slit 200), and the like. .

Here, other methods that can be used for forming the slit 200 include the following.
One of the etching techniques that has been widely used in the MEMS field is the Bosch process. In the Bosch process, SF ₆ gas and C ₄ F ₈ gas are alternately used for etching.
In recent years, the SHARP (Super High Aspect Ratio Process) process of ALCATEL has attracted attention as an etching technique used for forming a fine pattern. Also in this process, the etching is performed by alternately using SF ₆ gas and C ₄ F ₈ gas. Then, after the etching, O ₂ gas is introduced to form an oxide film on the surface to protect the surface. However, since O ₂ gas is used in this method, the resist, which is an organic substance, reacts with O ₂ and is discharged as gas when plasma is generated. Therefore, the resist mask selection ratio (the etching depth relative to the resist thickness) is reduced. Ratio) will be low. For example, the limit is to etch through an SOI wafer having an active Si layer of about 2.5 μm.
Therefore, it is considered that the resist material R2 for forming a resist mask and Al or SiO _2. However, in the case of using Al, there is a possibility that the plasma generated at the time of etching causes Al to become particles and move in the atmosphere, which adheres to the unmasked portion and impairs pattern reproducibility. In addition, when SiO ₂ is used, there is a problem that the reproducibility of a fine pattern is low.
Further, when the fine slit 200 is formed, each time the SF ₆ gas and the C ₄ F ₈ gas are alternately switched, as shown in FIG. 14A, a scallop (a wave-like surface is formed on the side surface of the groove formed by etching. There is also a problem that occurs. In the case of a fine pattern, when a scallop is formed, it is disadvantageous in terms of capacitance and the like.

As described above, the conventional etching method is not sufficient to form a fine slit 200 having a line width of 100 nm. On the other hand, as a result of trial and error by the present inventors, it has been found that it is effective to perform etching using a mixed gas of SF ₆ gas and C ₄ F ₈ gas.
By using a mixed gas of SF ₆ gas and C ₄ F ₈ gas, the selection ratio, which was about 1: 4 in the conventional SHARP process of ALCATEL, was improved to 1:13 or more. As a result, for example, when a pattern having a line width of 200 nm is formed on a Si substrate, it has hitherto been limited to etching at a depth of about 2.5 μm, but can be etched at a depth of about 8 μm. Furthermore, as shown in FIG. 14B, there was also a merit that no scallop was generated on the side surface of the groove formed by etching.
Therefore, it is preferable to use the method as described above in this step.

Next, as shown in FIG. 7B, the resist material R <b> 2 is removed from the surface of the active Si layer 53.
Thereby, the pattern formation process by EB is complete | finished and it transfers to the pattern formation process by a stepper etc. In the stepper or the like, the substrate material 50 is aligned using a dedicated alignment mark formed separately from the alignment mark M formed for EB.

As shown in FIG. 7C, in the pattern forming process in the stepper, first, a resist material R3 is applied to the surface of the active Si layer 53.
Next, as shown in FIG. 8A, in order to form a ground electrode, the stepper is exposed to a predetermined position of the resist material R3 using a mask and then developed. Thereby, the ground electrode pattern P3 is formed on the resist material R3.
Then, as shown in FIG. 8B, the portion of the ground electrode pattern P3 formed on the resist material R3 by the D-RIE method has a depth corresponding to the thickness of the active Si layer 53 (this embodiment). In this case, etching is performed at 2 μm. As a result, the box layer 52 is exposed through the active Si layer 53.
Further, as shown in FIG. 8C, the box layer 52 is removed at the portion of the ground electrode pattern P3 with the BHF solution, and the support substrate 51 is exposed.

Thereafter, as shown in FIG. 9A, the resist material R3 is peeled off by acetone or IPA, and then the resist material R4 is applied again as shown in FIG. 9B.
Next, as shown in FIG. 9C, in order to form the connection electrodes 30b and 40b that are electrically connected to the drive electrode 30a and the detection electrode 40a, the stepper is exposed to a predetermined position of the resist material R4 using a mask. After development, develop. Thereby, the electrode pattern P4 is formed in the portion where the resist material R4 has been removed by exposure. At this time, the portion of the ground electrode pattern P3 is also exposed and developed simultaneously to remove the resist material R3 and expose the ground electrode pattern P3.

Subsequently, as shown in FIG. 10A, Ti and Pt are respectively formed on the surface of the substrate material 50 with a predetermined film thickness by a sputtering method. At this time, desirable film thicknesses of the Ti / Pt film 60 are 10 to 100 nm for the Ti film and 10 nm to 1 μm for the Pt film. Further, instead of Ti, other substances such as Cr, Ta, TiW can be used. In addition to Pt, other materials such as Au, Al, AlSi, W, and Poly-Si can be substituted.
As shown in FIG. 10B, after sputtering, the substrate material 50 is immersed in acetone or a resist remover to lift off the resist material R4 and the Ti / Pt film 60 on the resist material R4. Then, the Ti / Pt film 60 remains only in the portions of the ground electrode pattern P3 and the electrode pattern P4, which become the connection electrodes 30b and 40 and the ground electrodes 61 and 62.

Next, as illustrated in FIG. 10C, a resist material R <b> 5 is applied to the back surface (the support substrate 51 side) of the substrate material 50.
Then, as shown in FIG. 11A, a stepper or the like uses a mask to expose a region P5 corresponding to the vibrator 20, and then develops it. Thereby, the support substrate 51 is in a state where the region P5 corresponding to the vibrator 20 is exposed.

Subsequently, as illustrated in FIG. 11B, a resist material R <b> 6 is applied to the surface of the substrate material 50.
And as shown in FIG.11 (c), in the stepper, after developing the pattern P6 for forming the structure as a device of the sensor 10, it develops. Here, the slit-shaped pattern P2 having a line width of 100 nm patterned by EB and the pattern P6 for forming the device structure are aligned. At this time, as shown in FIG. 6, since the slit-like pattern P2 formed by EB irradiation is formed thick in the portion where the pattern P6 for forming the device structure is overlapped, the pattern P2 If the pattern P6 forming the device structure is displaced, there is no problem as long as the pattern P6 is within a thick range, and alignment can be performed reliably.

  Then, as shown in FIG. 12 (a), a portion corresponding to the thickness of the active Si layer 53 is formed on the portion of the pattern P6 that forms the device structure that is not covered with the resist material R6 by the D-RIE method. Etching is performed (2 μm in this embodiment). As a result, the box layer 52 is exposed through the active Si layer 53 in the portion of the pattern P6 that forms the device structure.

  Next, as shown in FIG. 12B, a bulk wafer 70 is bonded to the surface side of the substrate material 50 to which the resist material R6 is applied, and the structure formed on the substrate material 50 in the process is shown. Prevent damage.

  Thereafter, as shown in FIG. 12 (c), on the back side of the substrate material 50, a portion not covered with the resist material R5, that is, a portion corresponding to the vibrator 20 is etched by the D-RIE method. The support substrate 51 is removed, and the box layer 52 is exposed.

Subsequently, as shown in FIG. 13A, the bulk wafer 70 is peeled off from the substrate material 50, and the resist materials R5 and 6 are further removed by acetone or IPA, and then O _{2 on} both surfaces of the substrate material 50 is further removed. The remaining resist is completely removed with ashing or a resist remover.

Thereafter, as shown in FIG. 13B, a portion of the box layer 52 corresponding to the vibrator 20 is removed with a BHF solution.
Furthermore, the sensor 10 as shown in FIG. 1 can be formed by performing water washing and IPA drying.

Here, using a Novec HFE (hydrofluoroether) -7200 (trade name) manufactured by Sumitomo 3M Limited, a deposition film (a film made of a CF2 polymer) generated when C ₄ F ₈ gas is introduced is used. Can be peeled off. This resist remover has a lower surface tension and lower latent heat of vaporization than IPA. Therefore, by performing the treatment using the resist remover after the water washing, the resist remover enters the narrow gap portion, and the deposit film can be reliably removed.

In addition, although each process was demonstrated in the said embodiment, it can replace with another method suitably.
For example, the process of forming the ground electrodes 61 and 62 shown in FIGS. 8A to 10B can be replaced with the following process.
As shown in FIG. 15A, in order to form the ground electrodes 61 and 62, exposure is performed on a predetermined position of the resist material R3 using a mask in a stepper, and then development is performed. As a result, a ground electrode pattern P3 ′ is formed on the resist material R3.
Then, as shown in FIG. 15B, the portion of the ground electrode pattern P3 ′ formed on the resist material R3 has a depth corresponding to the thickness of the active Si layer 53 (2 μm in the present embodiment). Etch. As a result, the box layer 52 is exposed through the active Si layer 53. At this time, a taper etching method is used for the etching so that the cross-sectional shape of the etching portion 80 becomes a tapered shape in which the cross-sectional area gradually decreases from the surface of the active Si layer 53 toward the support substrate 51 side. As such a taper etching method, for example, there is an ICP (Inductively Coupled Plasma) method.

Further, as shown in FIG. 15C, the resist material R3 is peeled off by acetone or IPA, and after O ₂ ashing, the resist material R8 is applied again as shown in FIG. 16A.
Then, as shown in FIG. 16B, in order to form the ground electrodes 61 and 62, the stepper is exposed to a predetermined position of the resist material R8 using a mask and then developed. Thereby, the electrode pattern P4 is formed in the portion where the resist material R8 has been removed by exposure.
Subsequently, as shown in FIG. 16C, a portion corresponding to the thickness of the active Si layer 53 is formed on the portion of the electrode pattern P4 not covered with the resist material R8 by the D-RIE method (this embodiment). In this embodiment, etching is performed at 2 μm). As a result, the box layer 52 is exposed through the active Si layer 53 in the electrode pattern P4.

Next, as shown in FIG. 17A, the box layer 52 in the electrode pattern P4 is removed with a BHF solution.
Further, as shown in FIG. 17B, after removing the resist material R8 with acetone or IPA, O ₂ ashing is performed on both surfaces of the substrate material 50 to remove the resist material R8 remaining on the front and back surfaces.

Subsequently, as illustrated in FIG. 17C, a resist material R <b> 9 is applied to the surface of the substrate material 50. Then, as shown in FIG. 18A, in the stepper, the portions of the ground electrode pattern P3 ′ and the electrode pattern P4 are exposed and then developed.
Then, as shown in FIG. 18 (b), Cr / Au film 90 is formed on the surface of the substrate material 50 with a predetermined film thickness by sputtering, thereby forming a Cr / Au film 90. At this time, it is also possible to use other substances such as Ti, Ta and TiW instead of Cr. In addition, Au can be replaced with other materials such as Pt, Al, AlSi, W, and Poly-Si.
As shown in FIG. 18C, after sputtering, the substrate material 50 is immersed in acetone, and the resist material R9 and the Cr / Au film 90 on the resist material R9 are lifted off. Then, the Cr / Au film 90 remains only in the portions of the ground electrode pattern P3 ′ and the electrode pattern P4, which become the connection electrodes 30b and 40b and the ground electrodes 61, 62, and 63.

Here, the resist material R9 applied in the step shown in FIG. 17C is for lifting off (removing) unnecessary portions of the Cr / Au film 90 formed in the sputtering step shown in FIG. 18B. It is. At this time, AZ5200NJ (trade name) manufactured by Clariant is preferably used as the resist material R9.
When a normal resist material (for example, a positive resist such as S1830 (trade name) or the like) is used as the resist material R9, when an unnecessary portion of the Cr / Au film 90 formed by sputtering with the resist material applied is lifted off, As shown in FIG. 19 (a), when removing the resist material R9 adhering to the wall surface of the groove or recess at the end of the groove or recess, as shown in FIG. 19 (b) and FIG. 20, Cr / Au The film 90 is broken. At that time, there is a problem that particles (foreign matter) are generated from the Cr / Au film 90 and adhere to the surface of the substrate material 50.
Therefore, when the above-mentioned AZ5200NJ made by Clariant is used as the resist material R9, as shown in FIG. 18A, the end portion of the resist film formed by the resist material R9 has a reverse taper cross section, and the wall surface of the groove or the recess is formed. The adhesion of the resist material R9 can also be prevented. Thereafter, if sputtering is performed, the Cr / Au film 90 is formed on the surface of the resist material R9 and the pattern portion, and does not adhere to the walls of the grooves and the recesses. As a result, even when lift-off is performed, the end of the Cr / Au film 90 in the pattern portion is not broken, and generation of particles can be prevented.

Further, as shown in FIG. 15B, the portion of the ground electrode pattern P3 ′ has a tapered shape in which the sectional shape gradually decreases from the surface of the active Si layer 53 toward the support substrate 51. Etched into. When this portion is sputtered, as shown in FIG. 18B, a Cr / Au film 90 is also formed on the tapered surface (inclined surface) of the etched portion 80. A through electrode (through via) that continues to the surface of the active Si layer 53 can be formed, and the ground electrode 63 is formed.
Here, other methods such as an electroforming process can be used to form the through electrode.
Thus, by forming the ground electrodes 61 and 62 on the surface of the support substrate 51, the following merits are produced.
That is, the ground electrodes 61, 62, and 63 are provided to set the potential of the vibrator 20 to 0 (zero) in order to set the reference potential of the output from the drive electrode 30a and the detection electrode 40a. In order to reduce the potential of the vibrator 20 to 0, conventionally, as shown in FIG. 21, wiring 95 connecting the vibrator 20 and the ground electrodes 61 and 62 is performed using a wire bonder. However, this has a problem that it takes time and labor for wire bonding. Further, when the sensor 10 is evaluated using a measurement probe, the layout of the drive electrode 30a, the detection electrode 40a, and the ground electrodes 61 and 62 needs to correspond to the electrode layout of a commercially available measurement probe. However, when wiring 95 is performed using a wire bonder, the layout is limited, and it is difficult to obtain an electrode layout corresponding to the measurement probe. On the other hand, by forming the ground electrodes 61, 62, and 63 by the through electrodes, the degree of freedom in layout increases, and as shown in FIG. 22, the connection electrode 30b of the drive electrode 30a, the connection electrode 40b of the detection electrode 40a, The electrode layout of the ground electrodes 61, 62, 63 can correspond to the measurement probe 300. This makes it possible to evaluate the sensor 10 more easily.

In the above embodiment, the sensor 10 having the configuration as shown in FIG. 1 is taken as an example. However, a sensor or a resonator manufactured by applying the present invention has a shape as long as it does not depart from the gist of the present invention. There is no intention to limit the configuration, material, and the like, and other shapes, configurations, materials, and the like can be appropriately used. In this case, the present invention can provide the same effects as described above.
Further, the manufacturing method of the sensor 10 described in the above embodiment and various methods specifically mentioned can be appropriately changed.
Further, here, a disk-type vibrator capable of obtaining high performance is taken as an example of the vibrator. However, the vibrator is not limited to the disk-type. It may be rectangular or square. In this case, the drive electrode and the detection electrode are parallel plate types, and the processing becomes easier.
In the above-described steps, the BHF solution is used for removing the oxide film. Of course, other oxide film removing methods may be used. Similarly, the D-RIE method is used for etching, but other silicon etching methods may be used.
In addition to this, as long as it does not depart from the gist of the present invention, the configuration described in the above embodiment can be selected or changed to another configuration as appropriate.

It is a figure which shows the structure of the sensor in this Embodiment. It is a figure which shows the manufacturing process of the sensor in this Embodiment. It is an example of an alignment mark. It is a figure which shows a state when the alignment mark of FIG. 3 is visually recognized with the EB pattern formation apparatus. It is a figure which shows the manufacturing process of the sensor in this Embodiment, and is a figure which shows the process following FIG. It is a figure which shows the superposition state of the pattern formed by EB, and the pattern formed by a stepper. It is a figure which shows the manufacturing process of the sensor in this Embodiment, and is a figure which shows the process following FIG. FIG. 8 is a diagram showing a step following FIG. FIG. 9 is a diagram showing a step following FIG. FIG. 10 is a diagram illustrating a process following FIG. 9. FIG. 11 is a diagram illustrating a process following FIG. 10. It is a figure which shows the process following FIG. It is a figure which shows the process following FIG. (A) is a microscope picture which shows the scallop which arose in the etching part, (b) is a microscope picture which suppressed generation | occurrence | production of the scallop in an etching part by using mixed gas. It is a figure which shows the example at the time of replacing the process of forming the ground electrode shown to Fig.8 (a) from FIG.10 (b) with another method. It is a figure which shows the process following FIG. FIG. 17 is a diagram showing a step following FIG. It is a figure which shows the process following FIG. It is a figure which shows a mode that the edge part of a sputtered film is cut off by the lift-off of a resist material. It is a microscope picture which shows the example of the state which the edge part of the sputtered film cut off. It is a figure which shows the example which forms a ground electrode using the wiring by wire bonding. It is a figure which shows the electrode layout corresponding to the layout of the probe for a measurement.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Sensor, 20 ... Vibrator, 30a ... Drive electrode (electrode), 30b, 40b ... Connection electrode, 40a ... Detection electrode (electrode), 50 ... Substrate material, 51 ... Support substrate, 52 ... Box layer, 53 ... Active Si layer (Si layer), 61, 62, 63 ... ground electrode, M ... alignment mark, R1-R9 ... resist material

Claims (7)

A method of manufacturing a sensor comprising: a vibrator; and an electrode that is disposed on the outer periphery of the vibrator with a gap therebetween and detects vibration of the vibrator or a change in vibration of the vibrator.
In a substrate material constituting the detection sensor, a first pattern forming step of patterning a gap portion between the vibrator and the electrode by electron beam irradiation;
A second pattern forming step of patterning a portion other than the gap portion between the vibrator and the electrode by exposing light having a wavelength longer than that of the electron beam;
The manufacturing method of the sensor characterized by including. In the substrate material composed of a base support substrate, a box layer made of Si oxide formed on the support substrate, and a Si layer formed on the box layer and forming the vibrator, Further comprising a step of forming an alignment mark for aligning the substrate material in the first pattern forming step and the second pattern forming step,
2. The sensor according to claim 1, wherein in the step of forming the alignment mark, at least the alignment mark used in the first pattern forming step is formed on the Si layer so as not to reach the box layer. Manufacturing method.   3. The sensor manufacturing method according to claim 1, wherein, in the first pattern formation step, an oxide film formed on the surface of the substrate material is removed prior to pattern formation by electron beam irradiation. Method.   In the first pattern forming step, the width of the pattern formed by electron beam irradiation is formed wider than the other portions in the portion where the pattern formed in the second pattern forming step is overlapped. The method for manufacturing a sensor according to claim 1, wherein: In the second pattern formation step, when forming a connection electrode that is electrically connected to the electrode and connected to an external power supply or detection circuit, and a ground electrode on the support substrate,
After the resist material is applied to the substrate material in a range including the pattern portion formed in the first pattern forming step, the resist material is removed from the connection electrode and the ground electrode portion, and the connection electrode 5. The method of manufacturing a sensor according to claim 1, wherein the metal constituting the ground electrode is vapor-deposited or sputtered, and then the resist material is removed.   6. The sensor manufacturing method according to claim 1, wherein the sensor detects the amount of the substance attached to the vibrator. A method of manufacturing a resonator comprising: a vibrator; and an electrode disposed on the outer periphery of the vibrator with a gap therebetween,
In the substrate material comprising a support substrate serving as a base, a box layer made of Si oxide formed on the support substrate, and an Si layer formed on the box layer and forming the vibrator, A first pattern forming step of patterning a gap portion between the child and the electrode by electron beam irradiation;
Including a second pattern formation step of patterning a portion other than the gap portion between the vibrator and the electrode by exposing light having a wavelength longer than that of the electron beam,
Prior to the first pattern formation step, an alignment mark is formed on the Si layer so as not to reach the box layer,
In the first pattern forming step and the second pattern forming step, the substrate material is aligned using the alignment mark, and pattern formation is performed.

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