KR100758822B1 - Highly sensitive field effect transistor type bio sensor and method of manufacturing the same - Google Patents

Abstract

A highly sensitive field effect transistor type bio sensor is provided to increase driving current and physical contacting area with a bio sensing target material, and enhance electric capacity of the device by structurally modifying the shape of a semiconductor substrate, and improve sensing reproducibility and accuracy of the bio sensor by increasing S/N ratio(signal to noise ratio) of the bio sensor. A highly sensitive field effect transistor type bio sensor comprises: a gate insulating membrane(203) deposited on a semiconductor substrate; a gate electrode(204) formed on the gate insulating membrane; a source region(201) and a drain region(202) formed in both sides of the gate insulating membrane; and a bio sensing membrane formed on the gate electrode, wherein a reference electrode is formed on the gate electrode and the semiconductor substrate has at least one predetermined prominence and depression part. The prominence and depression part is prepared by coating a polymer thin film with resist materials, performing an imprinting process on the resist with a micro stamp, repeating the imprinting process to form the pattern on the total substrate, removing a residual layer from the resist, and forming a predetermined shape on the semiconductor substrate with the resist pattern as a mask.

Description

High sensitivity field effect transistor type biosensor and manufacturing method thereof {HIGHLY SENSITIVE FIELD EFFECT TRANSISTOR TYPE BIO SENSOR AND METHOD OF MANUFACTURING THE SAME}

1 is a cross-sectional view of a field effect transistor type biosensor according to the prior art.

2 is a plan view illustrating a field effect transistor type biosensor according to an embodiment of the present invention.

3 is a cross-sectional view in the direction of the channel width W between the source 201 and the drain 202.

FIG. 4 is a view illustrating a process of forming irregularities on a semiconductor circuit board using an imprint process using a micro stamp.

5 is a cross-sectional view illustrating various shapes of an uneven portion that may be formed on a substrate of the field effect transistor according to an embodiment of the present invention.

<Explanation of symbols for main parts of the drawings>

101: semiconductor substrate 108: reference electrode

201: source region 202: drain region

203: gate insulating film 204: gate electrode

430: micro stamp

The present invention relates to a field effect transistor type biosensor and a method for manufacturing the same, and more particularly, to structurally change the shape of a semiconductor substrate to increase the driving current of the device and the physical contact area with the bio-sensing target material and improve electrical performance. The present invention relates to an improved field effect transistor type biosensor and a method of manufacturing the same.

Biosensors selectively detect chemicals (especially complex organic compounds) contained in a sample by using a biological sensing function in which a living organism reacts sensitively to a specific substance such as an enzyme or an antibody, or a microorganism. A chemical sensor used for measurement. The biosensor is a sensor that can quickly quantify the concentration of various bioactive substances by using the intermolecular selective reactivity of the biomaterial alone, and it is a small analytical combination of the biomaterial and the conventional physical, chemical and optical signal transducers. It is a bioelectronic tool, and biochip technology is the first to apply electrical signals from various biochemical reactions.

The biggest advantage of analytical methods using biosensors compared to conventional analytical methods is that they can be analyzed quickly and easily without going through a complex process such as processing a sample. This requires that the biological material reacting with the analyte be immobilized in the receptor. A method of confining a large molecular weight biomaterial in a polymer membrane or a sol-gel membrane or fixing the biomaterial on a solid substrate by chemical bonding is used.

The first biosensor was known as a Glucose sensor manufactured by Clark using a dialysis membrane to measure glucose in 1962. In the early days, most enzymes were immobilized on a signal transduction device, but recently, with the rapid development of molecular biology, Sensors manufactured using monoclonal antibodies or antibody-enzyme conjugates have been developed and used. In addition, research on the development of chip sensors such as DNA chips and protein chips for processing a large amount of genetic information at high speed is encouraging, and many efforts are being made to develop advanced sensors incorporating molecular biology technology, nanotechnology and information and communication technology. This is concentrated.

Biosensors designed to measure specific materials using biomaterials that selectively react only with specific materials have advantages not found in many other types of physical and chemical sensors. However, due to the instability of the biomaterial itself, the activity decreases with repeated measurements, and thus there is an inconvenience of frequently replacing the sensing film. Recently, due to the introduction of thick film device manufacturing technology, mass production is possible at low production cost, and products that treat the sensor as a single-use and attach it to the main body of the measuring machine are discarded after one measurement. The situation is leading the direction of product development of the sensor.

A field effect transistor type biosensor is a microminiature manufactured by a microfabrication technique such as a semiconductor integrated circuit process and refers to a sensor that operates on the same principle as a field-effect transistor. Field effect transistor type sensors are manufactured in combination with advanced technologies such as new material technology, sophisticated microfabrication technology, electronic circuit integration technology, and artificial intelligence technology, and have many advantages such as miniaturization, multidimensionalization, multifunction, intelligence, and systemization of the sensor. Have. Field-effect transistor-type biosensors can integrate many sensor elements on a single chip, multidimensional by arranging several same types of sensors, multifunctional by integrating different types of sensors together, and with intelligent circuits. It is becoming very popular as a state-of-the-art sensor because it can be intelligent by integration and systemized by integrating related circuits and devices together.

US Patent No. 4,238,757, filed in 1980, is a source patent for measuring biological responses using field effect transistors. It relates to a biosensor that measures the antigen-antibody reaction as a change in the semiconductor inversion layer due to a change in surface charge concentration, which includes proteins in the biomolecule. I was. U.S. Patent No. 4,777,019, filed in 1986, adsorbs bio monomers onto a gate surface to measure the degree of hybridization with complementary monomers with a field effect transistor. Subsequently, U.S. Patent No. 5,846,708, filed in 1998, discloses a method of measuring hybridization by absorbance by a bound biomolecule using a charged coupled device (CCD). In addition, US Pat. Nos. 5,466,348 and 6,203,981 disclose a description of using a thin film transistor (TFT) and incorporating a circuit to improve a signal-to-noise ratio (S.N ratio). In the case of using the TFT, the cost can be reduced compared to the transistor formed on the silicon substrate, and there is an advantage in that an array type chip can be manufactured in which the integration degree is improved by increasing the substrate area.

1 is a cross-sectional view of a field effect transistor type biosensor according to the prior art.

Referring to FIG. 1, a conventional field effect transistor type biosensor has four terminals including a substrate 101, a source region 102, a drain region 103, and a gate 107. And metal wires. Here, in the general field effect transistor, all four terminals are connected to the measurement circuit to send and receive electrical signals and are controlled by the measurement circuit. Unlike the gate of the general field effect transistor is protected by an insulating protective film, the gate surface of the field effect transistor type biosensor also has a measurement circuit by stacking a biosense layer 106 that reacts with a material to be measured, that is, a liquid sample. There is a fundamental difference that you cannot connect directly to. For this reason, in order to normally use the field effect transistor type sensor, a method of applying the gate voltage of the field effect transistor type sensor by impregnating the reference electrode 108 together with the measurement sample solution and connecting to the measurement circuit is generally used. do.

The use of such a field effect transistor type biosensor has a great advantage in that it costs less time and time than in the conventional method and is easy to integrate with an integrated circuit (ICS) / MEMS process. However, such a conventional field effect transistor type biosensor exhibits a low S / N ratio in actual experiments and has a large disadvantage of low reproducibility and accuracy.

A field effect transistor type biosensor using a reference electrode 108 has an electrical potential between the source 102 and the reference electrode 108 and the drain 103 and the reference electrode 108 according to the basic operating principle. potential). Biomolecules charged by electro-kinetic force under the influence of their electric field are not uniformly distributed on the gate 107 between the source 102 and the drain 103, The distribution is wrong. For example, when a DNA having negative charge is measured using a p-type field effect transistor, the immobilization rate of the probe DNA or the degree of hybridization of the target DNA is relatively high between the source 102 and the reference electrode 108. Under the influence of the electric field, the immobilization rate of the probe DNA and the hybridization rate of the target DNA on the gate 107 near the source become high. Accordingly, the charge density of the biomolecule attached to the gate surface directly affects the current change of the field effect transistor type biosensor. As such, since the charge density on the gate varies depending on its position, a method of improving the gate structurally and increasing the signal-to-noise ratio of the field effect transistor type biosensor is required.

The present invention has been made to improve the prior art as described above, the structure of the semiconductor substrate to improve the field effect transistor to increase the drive current and physical contact area of the device and the bio-sensing target material structurally to improve the electrical performance An object of the present invention is to provide a type biosensor and a method of manufacturing the same.

Still another object of the present invention is to provide an electrically stable gate reference voltage to the field effect transistor type biosensor to increase the reliability of the output signal.

Another object of the present invention is to improve the reproducibility and accuracy by implementing a high signal-to-noise ratio (S / N) ratio through structural improvement of the shape of the semiconductor substrate of the field effect transistor type biosensor to improve electrical performance. do.

The present invention to achieve the above object and to solve the problems of the prior art, the present invention is a gate insulating film stacked on a semiconductor substrate; A gate electrode formed on the gate insulating film; Source and drain regions in contact with the gate insulating layer and formed at both sides thereof; And a bio-sensing film formed on the gate electrode, wherein the semiconductor substrate provides a field-effect transistor-type biosensor, wherein at least one predetermined portion is formed.

According to one aspect of the invention, the step of stacking a gate insulating film on a semiconductor substrate; Forming a gate electrode on the gate insulating film; Contacting the gate insulating layer to form source and drain regions on both sides; And forming a biosensor film on the gate electrode, wherein the field effect transistor type biosensor comprises forming a predetermined one or more uneven portions on the semiconductor substrate. Provided is a method of manufacturing an effect transistor type biosensor.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention;

2 is a plan view illustrating a field effect transistor type biosensor according to an embodiment of the present invention.

Referring to FIG. 2, a field effect transistor type biosensor is formed on a substrate on which an uneven portion is formed, and includes a gate insulating film 203, a gate electrode 204, a source electrode 201, a drain electrode 202, and a biosense film. .

The gate insulating layer 203 and the gate electrode 204 are sequentially formed on the uneven portion of the substrate, and the gate electrode 204 is deposited only at a desired position on the uneven portion of the substrate by using a shadow mask. In addition, the gate insulating layer 203 is formed by depositing a high dielectric constant inorganic insulating material on the entire surface of the substrate on which the gate electrode is formed.

The substrate may be made of silicon itself, or may be formed by further depositing silicon on an insulator (SOI).

3 is a cross-sectional view in the direction of the channel width W between the source 201 and the drain 202.

Referring to FIG. 3, a gate insulating film 203 and a gate electrode 204 are sequentially formed on a semiconductor substrate having a predetermined shape formed by a micro stamp, and a biosense film is formed on the semiconductor substrate 301 on which the gate insulating film and the gate electrode are formed. 302 is stacked.

The biosensor layer 302 is composed of a film capable of sensing a biomolecule recognition material such as DNA, RNA, or protein, and is formed by depositing on the gate region.

In the field effect transistor, the ratio of the width (W) of the gate to the length (L) of the gate serves as an important factor in determining the I-V characteristic of the device. Therefore, even if the widths W and lengths L of the gates are different from each other, the same electrical characteristics are exhibited when the W / L ratios are the same. The saturation region current of the field effect transistor can be calculated by Equation 1 below.

In Equation 1, ISD is source-drain current, μ is charge mobility, C0 is capacitance of oxide, W is channel width, L is channel length, and VG is gate voltage. And VT is the threshold voltage.

From Equation 1, it can be seen that the source-drain current ISD is closely related to the structural factors of the field effect transistor, and the source-drain current ISD can be increased by increasing the value of W / L in the field effect transistor. .

2 and 3, as a result of forming the gate insulating film 203 and the gate electrode 204 formed between the source 201 and the drain 202 along the uneven shape of the substrate, an electric field formed on a conventional substrate. Rather than the effect transistor, the field effect transistor according to the present invention can increase the width W of the channel. Therefore, the field effect transistor according to the present invention can increase the ratio of W / L than the conventional field effect transistor, and can also increase the drive current during the ON operation of the transistor as described above in Equation 1 above. do.

Field effect transistor type biosensors are generally divided into p-type and n-type according to the type of channels, such as MOSFET (metal oxide silicon field effect transistor). In the case of measuring negatively charged biomolecules, a p-type field effect transistor type biosensor is used to apply a negative bias to a reference electrode relative to a source, which is a first impurity region. And the binding of the target biomolecule. Therefore, not only the negatively charged biomolecule and the p-type field effect transistor type biosensor, but also the same may be applied to the n-type field effect transistor type biosensor of the positively charged biomolecule.

FIG. 4 is a view illustrating a process of forming irregularities on a semiconductor circuit board using an imprint process using a micro stamp.

Referring to FIG. 4, in step I, a resist is coated on the semiconductor circuit board 410 and hard baked to form a resist layer 420. The micro stamp 430 having a predetermined shape in step II is pressed onto the resist layer 420 so that the predetermined shape of the micro stamp is formed in the resist. In step III, the micro stamp 430 is separated from the resist layer 420. Dry / wet etching is performed using the resist layer having the shape selected in step IV as a mask to form the uneven portion having the same shape as that of the micro stamp on the semiconductor circuit board. Thereafter, a shadow insulating layer 203 is formed by depositing a high dielectric constant inorganic insulating material on the entire substrate where the gate region is formed using a shadow mask only at a desired position on the uneven portion of the semiconductor substrate. Then, the gate electrode 204 is formed by depositing a metal material, and the biosensor 302 is formed on the gate electrode through a predetermined process.

According to the above method, a small area stamp can be manufactured, and a step-and-repeat method of performing an imprint process on a part of a semiconductor circuit board and repeating work by moving a stamp position is performed. It is possible.

As the material of the micro stamp, a semiconductor material such as silicon (Si), silicon oxide (SiO 2), a metal material such as nickel (Ni), a transparent material such as quartz, and polymer materials may be used. In addition, as the imprint method, a thermosetting imprint technique for applying a heat to form a resist and an ultraviolet curing imprint technique for curing and molding a polymer of a resist using ultraviolet light while pressing with a stamp may be used.

A micro stamp which is the most important role of the imprint process of FIG. 4 is manufactured. The micro stamp is manufactured by using a wafer on which an oxide layer having a predetermined thickness is formed on a substrate. The PMMA polymer is applied to the wafer and then patterned into a shape to be formed on the gate through lithgraphy. After the pattern is developed with a developer, dry etching of the oxide layer using a reactive ion etch (RIE) apparatus completes the manufacture of a micro stamp having a desired shape.

5 is a cross-sectional view illustrating various shapes of an uneven portion that may be formed on a substrate of the field effect transistor according to an embodiment of the present invention.

Referring to FIG. 5, the substrate of the field effect transistor is provided with various uneven parts according to the shape of the micro stamp as shown in (a) to (d), so that the W / L of the unit field effect transistor according to the use is determined. Can increase the ratio.

In the present invention as described above has been described by the specific embodiments, such as specific components and limited embodiments and drawings, but this is provided to help a more general understanding of the present invention, the present invention is not limited to the above embodiments. For those skilled in the art, various modifications and variations are possible from such description.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and all the things that are equivalent to or equivalent to the claims as well as the following claims will belong to the scope of the present invention. .

According to the present invention, there is provided a field effect transistor type biosensor and a method of manufacturing the same, which structurally improves the shape of a semiconductor substrate to increase the physical current of the device and the physical contact area with the biosense target material and improve electrical performance.

In addition, according to the present invention, it is possible to increase the reliability of the output signal by providing an electrically stable gate reference voltage to the field effect transistor type biosensor.

In addition, according to the present invention, it is possible to improve the reproducibility and accuracy by implementing a high S / N (signal-to-noise) ratio through the structural improvement of the shape of the semiconductor substrate of the field effect transistor type biosensor to improve the electrical performance.

Claims (16)

A gate insulating layer stacked on the semiconductor substrate; A gate electrode formed on the gate insulating film; Source and drain regions in contact with the gate insulating layer and formed at both sides thereof; And A biosensor film formed on the gate electrode In the field effect transistor type biosensor comprising: The reference electrode is formed on the gate electrode, and the semiconductor substrate is a field effect transistor type biosensor, characterized in that at least one uneven portion is formed. delete delete The method of claim 1, The uneven portion formed on the semiconductor substrate, Coating a resist material on the polymer thin film; Performing an imprint process locally using a micro stamp on the resist; Repeating an imprint process while moving the micro stamp to form a pattern for the entire substrate; Removing the radial layer of the resist; And Forming a predetermined shape on the semiconductor substrate using the resist pattern as a mask; Field effect transistor type biosensor characterized in that the irregularities produced by. delete delete delete The method of claim 1, The bio-sensing membrane is a field effect transistor type biosensor, characterized in that the biomolecule consisting of any one of DNA, RNA or protein. Depositing a gate insulating film on the semiconductor substrate; Forming a gate electrode on the gate insulating film; Contacting the gate insulating layer to form source and drain regions on both sides; And Forming a biosensor layer on the gate electrode In the manufacturing method of the field effect transistor type biosensor comprising: Forming at least one predetermined portion of the uneven portion in the semiconductor substrate; And Forming a reference electrode on the gate electrode Method of manufacturing a field effect transistor type biosensor comprising a. delete delete The method of claim 9, The forming of the at least one recessed portion on the semiconductor substrate may include: Coating a resist material on the polymer thin film; Performing an imprint process locally using a micro stamp on the resist; Repeating an imprint process while moving the micro stamp to form a pattern for the entire substrate; Removing the radial layer of the resist; And Forming a predetermined shape on the semiconductor substrate using the resist pattern as a mask; Method of manufacturing a field effect transistor type biosensor comprising a. delete The method of claim 12, The forming of the predetermined shape on the semiconductor substrate using the resist pattern as a mask is performed by dry etching or wet etching to pattern the manufacturing method of the field effect transistor type biosensor. delete The method of claim 9, The bio-sensing film is a method for producing a field effect transistor type biosensor, characterized in that the biomolecule consisting of any one of DNA, RNA or protein.

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