TW201307840A - Biosensor and manufacturing method thereof - Google Patents

Abstract

A biosensor and a manufacturing method thereof are disclosed. The manufacturing method comprises the following steps: forming a first electrode layer on one side of a substrate; etching the substrate to form a chamber; forming a piezoelectric layer on the side of the substrate; forming a second electrode layer on the piezoelectric layer; forming a bonding metal layer in the chamber and on the first electrode layer; forming a biocompatible metal layer on the bonding metal layer; and forming a bio-sensing layer on the biocompatible metal layer.

Description

Biosensor and method of manufacturing same

The present invention relates to a biosensor and a method of fabricating the same, and more particularly to a dual-mode film bulk acoustic resonator (FBAR) for fabricating a highly sensitive biosensor and Its manufacturing method.

In the field of environment, pharmacy or biomedicine, it is always a development goal to develop an analytical monitoring method that is simple in operation, fast in analysis and accurate in results, and can automatically and continuously perform multi-species and multi-samples.

With the advancement of semiconductor process technology, conventional sensor components have been upgraded from Surface Wave Acoustic (SAW) resonators to Film Bulk Acoustic Resonator (FBAR) resonators. Dual-mode film bulk acoustic resonator (FBAR) is mainly composed of upper and lower electrodes and a piezoelectric layer, which uses body elastic waves to propagate in solids, which can reduce energy loss and improve Quality factor. Among them, the body shape processing is one of the two-mode film bulk acoustic resonators, and the body shape processing method is to leave a structural layer from the back etching, thereby using air as a reflective layer to reduce loss.

However, the conventional film bulk acoustic resonator structure cannot be directly used for detecting biological targets, and thus it is impossible to manufacture a highly sensitive biosensor using the highly sensitive characteristics of the film bulk acoustic resonator.

SUMMARY OF THE INVENTION It is therefore an aspect of the present invention to provide a biosensor and a method of fabricating the same that utilizes a bimodal film bulk acoustic resonator (FBAR) structure to detect biomarkers to improve sensing sensitivity.

According to an embodiment of the present invention, the biosensor of the present invention comprises: a substrate, a first electrode layer, a piezoelectric layer, a second electrode layer, a bonding metal layer, a bio-organic metal layer, and a bio-detection layer. The substrate has a cavity for accommodating a biological target to be tested, a first electrode layer is formed on one side of the substrate, and a piezoelectric layer is formed on the side of the substrate, wherein the piezoelectric layer is at least partially covered by the substrate The first electrode layer has an inclined angle between the C axis of the piezoelectric layer and the substrate, which is less than 90 degrees. The second electrode layer is formed on the piezoelectric layer, the bonding metal layer is formed in the cavity, and is located on the first electrode layer, and the biological metal layer is formed on the bonding metal layer, and the biodetection layer Formed on the biophilic metal layer.

Moreover, in accordance with an embodiment of the present invention, a method of fabricating a biosensor of the present invention includes the steps of: providing a substrate; forming a first electrode layer on one side of the substrate; etching the substrate to form a cavity; forming a piezoelectric layer on the side of the substrate, wherein the piezoelectric layer at least partially covers the first electrode layer and exposes the first electrode layer, and between the C axis of the piezoelectric layer and the substrate Having an oblique angle, which is less than 90 degrees; forming a second electrode layer on the piezoelectric layer; forming a bonding metal layer in the cavity and located on the first electrode layer; forming a biological metal layer On the bonding metal layer; and forming a bio-detection layer on the bio-organic metal layer.

In an embodiment of the invention, the angle of inclination is less than 70 degrees.

In an embodiment of the invention, the biosensor further includes a second protective layer formed on opposite sides of the substrate and exposing the cavity and the biological metal layer.

In an embodiment of the invention, the material of the bonding metal layer is chromium.

In an embodiment of the invention, the material of the biophilic metal layer is gold.

In an embodiment of the invention, the piezoelectric layer is made of aluminum nitride, zinc oxide or barium sulfide.

In an embodiment of the invention, the biodetection layer is a cysteine layer.

In an embodiment of the invention, the manufacturing method further includes the step of etching a portion of the piezoelectric layer to form the sloped sidewall on the piezoelectric layer.

In one embodiment of the invention, the biodetection layer is a cysteine layer, and the surface of the biophilic metal layer is immersed in the cysteine solution for a predetermined period of time to form the cystine layer.

Therefore, the biosensor of the present invention and the method of manufacturing the same can use the FBAR structure to detect a biological target, thereby greatly improving the sensing sensitivity. Moreover, the cavity of the biosensor can be directly used as a detecting tank to improve the convenience and accuracy of detection. Furthermore, the C-axis of the piezoelectric layer of the biosensor and the substrate may have an oblique angle for sensing a change in the horizontal component of the oscillation energy.

The above and other objects, features, advantages and embodiments of the present invention will become more apparent and understood. It is to be understood that the embodiments are not intended to limit the invention.

Please refer to FIG. 1 , which is a cross-sectional view of a biosensor according to an embodiment of the invention. The biosensor of the present embodiment can be used to detect a biological target to be tested (not shown), for example, to detect immunoglobulin E (IgE), immunoglobulin G (IgE) concentration or fetal globulin (AFP) index. The biosensor may include a substrate 110, a first electrode layer 120, a piezoelectric layer 130, a second electrode layer 140, a bonding metal layer 150, a bio-organic metal layer 160, a second protective layer 170, and a bio-detection layer 180. The substrate 110 has a cavity 111 for receiving the biological target to be tested. The first electrode layer 120 is formed on one side of the substrate 110, and the piezoelectric layer 130 is also formed on the side of the substrate 110. The piezoelectric layer 130 is at least partially covered on the first electrode layer 120 and exposes the first electrode. The layer 120 and the second electrode layer 140 are also formed on the side of the substrate 110 and formed on the piezoelectric layer 130. The bonding metal layer 150 is formed in the cavity 111 of the substrate 110 and located on the first electrode layer 120. The bio-active metal layer 160 is also formed in the cavity 111 of the substrate 110 and formed on the bonding metal layer 150. The bio-detection layer 180 is also formed in the cavity 111 of the substrate 110 and formed on the bio-organic metal layer 160. The protective layer 170 is formed on opposite sides of the substrate 110 and exposes the cavity 111 and the bio-detection layer 180.

As shown in FIG. 1 , the substrate 110 of the present embodiment is, for example, a substrate. The cavity 111 of the substrate 110 is recessed in the substrate 110 and exposes the biological detection layer 180 for receiving the biological target to be tested. It is convenient to carry out the detection of the biological target to be tested, and improve the accuracy of the detection of the biological standard. The material of the first electrode layer 120 may be a metal material such as aluminum, gold, molybdenum or platinum. In this embodiment, the material of the first electrode layer 120 may be platinum. The piezoelectric layer 130 is made of a piezoelectric material, such as aluminum nitride, zinc oxide or barium sulfide. In the present embodiment, the material of the piezoelectric layer 130 may be zinc oxide. The C-axis of the piezoelectric layer 130 and the substrate 110 have an inclination angle θ, and the inclination angle θ is at least less than 90 degrees, preferably less than 70 degrees, to increase the sensing sensitivity.

As shown in FIG. 1 , the material of the second electrode layer 140 of the present embodiment may be a metal material such as aluminum, gold, molybdenum or platinum. In this embodiment, the material of the second electrode layer 140 may be molybdenum. The bonding metal layer 150 is formed on the surface of the first electrode layer 120 exposed by the cavity 111 to improve the bonding strength between the bio-organic metal layer 160 and the first electrode layer 120, so that the bio-organic metal layer 160 It can be firmly bonded to the first electrode layer 120. In the present embodiment, the material of the bonding metal layer 150 is, for example, chromium. The bio-organic metal layer 160 is made of a highly bio-metallic material, such as gold, for forming and joining the bio-detection layer 180 within the cavity 111. In the present embodiment, the material of the bio-organic metal layer 160 is, for example, gold. The material of the protective layer 170 is, for example, tantalum nitride (SiNx) for protecting and supporting the substrate 110 in the process. The bio-detection layer 180 is used to capture the biomarker to be tested. In the present embodiment, the bio-detection layer 180 can be, for example, a cystine layer.

Referring to FIG. 2A to FIG. 2I, a schematic diagram of a process of a biosensor according to an embodiment of the present invention is shown. In the method of manufacturing the biosensor of the present embodiment, as shown in FIG. 2A, first, the substrate 110 is provided. Preferably, the substrate 110 is subjected to a cleaning process step in advance to clean the surface of the substrate 110. Next, as shown in FIG. 2B, protective layers 170 are formed on opposite side surfaces of the substrate 110, respectively. In the present embodiment, the protective layer 170 may be formed by a Low Pressure Chemical Vapor Deposition (LPCVD) method to form, for example, a tantalum nitride layer. Next, as shown in FIG. 2C, the protective layer 170 on the other side surface of the substrate 110 is patterned to form an etched window. In the present embodiment, the patterning method is, for example, a reactive ion etching process in a dry etching method. Next, as shown in FIG. 2D, a first electrode layer 120 (eg, platinum) is formed on the protective layer 170 on the side surface of the substrate 110, and a portion of the protective layer 170 is exposed, wherein the method of forming the first electrode layer 120 is It is DC sputter. Next, as shown in FIG. 2E, the substrate 110 is etched to form a cavity 111. In this embodiment, the protective layer 170 having an etched window may be used as a mask to etch the surface of the substrate 110 exposed by the etched window to form the cavity 111 and simultaneously expose the protective layer on the side surface. 170. The etching method of the substrate 110 may be a wet or dry etching method. At this time, a lithography process can be used to form a thick photoresist layer 102 on the first electrode layer 120.

Next, as shown in FIG. 2F, a piezoelectric layer (for example, zinc oxide) 130 is formed on the first electrode layer 120. The piezoelectric layer 130 is formed by RF sputter. Next, as shown in FIG. 2G, the thick photoresist layer 102 is removed to expose a portion of the surface of the first electrode layer 120. At this time, for example, a portion of the piezoelectric layer 130 may be etched to form the inclined sidewalls 131 on the piezoelectric layer 130. Next, as shown in FIG. 2H, a second electrode layer 140 (eg, molybdenum) is formed on the piezoelectric layer 130, wherein the second electrode layer 140 is formed by a DC sputter method. Next, as shown in FIG. 2I, the protective layer 170 exposed in the cavity 111 is etched to expose the first electrode layer 120. Next, the bonding metal layer 150, the biologically active metal layer 160, and the bio-detection layer 180 are sequentially formed on the first electrode layer 120 exposed in the cavity 111 to complete the bimodal film bulk acoustic wave as shown in FIG. Biosensor with resonator (FBAR) structure.

In the present embodiment, when, for example, a cystine layer is formed as the biodetection layer 180, the surface of the biosensor metal layer 160 of the biosensor may be immersed in the cysteine solution for a predetermined time (for example, 1 hour) to form the cystine layer, followed by DI water to clean the cystine layer.

When the biosensor of the embodiment is used to detect the biomarker to be tested, the cavity 111 of the biosensor may be open upward to serve as a detection trough for the instillation of the biomarker to be tested and By arranging, the biological target to be tested can be directly detected, thereby greatly improving the convenience of detection of the biological target. Moreover, since the biosensor is detected by a bimodal film bulk acoustic resonator (FBAR) structure with a high operating frequency, the sensing sensitivity can be greatly improved. When the biological target to be tested is detected in the cavity 111 of the biosensor, the change of the parameter of the biological target to be tested may cause the conductivity of the piezoelectric layer 130 to change, and further change the surface acoustic wave velocity of the piezoelectric layer 130. The relative oscillation frequency of the oscillator circuit (not shown) connected to the biosensor changes accordingly. Among them, the change of the acoustic wave velocity will be affected by the type of the biological target to be tested, such as microorganisms, enzymes, antibodies, and the like.

In this embodiment, the relationship between the amount of change in the wave velocity and the conductivity of the film can be expressed as:

Where Δv is the front-to-back wave velocity difference, v ₀ is the original wave velocity, k ² is the electromechanical coupling coefficient, σ is the pre-sensing film conductivity, and σ _m is the sensed film conductivity.

Furthermore, the C-axis of the piezoelectric layer 130 of the biosensor of the present embodiment may have an oblique angle with the substrate 110. Therefore, when the piezoelectric layer 130 oscillates, except in the vertical direction of the piezoelectric layer 130. In addition to the oscillating energy, a horizontal component change of the oscillating energy occurs in the horizontal direction of the piezoelectric layer 130, thereby increasing the detection and analysis basis of the biological target to be tested, and improving the biological sensor for the biological target to be tested. Sensing sensitivity.

It can be seen from the above embodiments of the present invention that the biosensor of the present invention can have a bimodal film bulk acoustic resonator (FBAR) structure with a high operating frequency, and can be used for detecting biological targets, thereby greatly improving the sensing. Sensitivity. And due to the structural design of the biosensor, the cavity of the biosensor can be directly used as a detecting tank to sense the biological target to be tested, thereby improving the convenience and accuracy of the detection of the biological label. Furthermore, compared with the general FBAR structure, the piezoelectric layer of the biosensor of the present invention has a slanted sidewall design for sensing the horizontal component variation of the oscillating energy, thereby further improving the sensing sensitivity of the biosensor. .

In view of the above, the present invention has been disclosed in the above preferred embodiments, and is not intended to limit the invention, and the present invention may be made without departing from the spirit and scope of the invention. Various modifications and refinements are made, and the scope of the present invention is defined by the scope of the appended claims.

102. . . Thick photoresist layer

110. . . Substrate

111. . . Cavity

120. . . First electrode layer

130. . . Piezoelectric layer

140. . . Second electrode layer

150. . . Bonding metal layer

160. . . Bio-organic metal layer

170. . . The protective layer

180. . . Bioassay layer

The above and other objects, features, advantages and embodiments of the present invention will become more apparent and understood.

1 is a cross-sectional view of a biosensor in accordance with an embodiment of the present invention.

2A to 2I are schematic diagrams showing the process of a biosensor according to an embodiment of the present invention.

110. . . Substrate

111. . . Cavity

120. . . First electrode layer

130. . . Piezoelectric layer

140. . . Second electrode layer

150. . . Bonding metal layer

160. . . Bio-organic metal layer

170. . . The protective layer

180. . . Bioassay layer

Claims (10)

A biosensor includes: a substrate having a cavity for accommodating a biological target to be tested; a first electrode layer formed on one side of the substrate; and a piezoelectric layer formed on the side of the substrate The piezoelectric layer is at least partially covered on the first electrode layer, and the C-axis of the piezoelectric layer has an oblique angle with the substrate, which is less than 90 degrees; a second electrode layer is formed on the a piezoelectric layer formed in the cavity and located on the first electrode layer; a bio-organic metal layer formed on the bonding metal layer; and a bio-detection layer formed on the piezoelectric layer On the biological layer of the metal. The biosensor of claim 1, wherein the tilt angle is less than 70 degrees. The biosensor of claim 1, further comprising: a second protective layer formed on opposite sides of the substrate and exposing the cavity and the biological metal layer. The biosensor of claim 1, wherein the material of the bonding metal layer is chromium. The biosensor of claim 1, wherein the material of the biophilic metal layer is gold. The biosensor of claim 1, wherein the piezoelectric layer is made of aluminum nitride, zinc oxide or barium sulfide. The biosensor of claim 1, wherein the biodetection layer is a cysteine layer. A method of manufacturing a biosensor, comprising: providing a substrate; forming a first electrode layer on one side of the substrate; etching the substrate to form a cavity; forming a piezoelectric layer on the side of the substrate The piezoelectric layer is at least partially covered on the first electrode layer, and exposes the first electrode layer, and the C-axis of the piezoelectric layer and the substrate have an oblique angle, which is less than 90 degrees; Forming a second electrode layer on the piezoelectric layer; forming a bonding metal layer in the cavity and located on the first electrode layer; forming a bio-organic metal layer on the bonding metal layer; and forming a A biodetection layer is on the biophilic metal layer. The method of claim 8, wherein the angle of inclination is less than 70 degrees. The method of claim 8, wherein the biodetection layer is a cysteine layer, and the surface of the biophilic metal layer is immersed in a cysteine solution for a predetermined period of time to form the cyst Amine acid layer.