KR102284252B1 - Tunneling field effect transistor biosensor and method for manufacturing the same - Google Patents

Abstract

In the present invention, a space for inserting a biomaterial is separately formed in a portion adjacent to a source region, and a separate gate capable of controlling an electric field at a portion into which the biomaterial is inserted is formed to sense the biomaterial of the existing biosensor. In order to overcome the volume limitation of and a first gate for forming a channel region between the regions, and a biomaterial sensing region formed with a source region interposed therebetween.

Description

Tunneling field effect transistor biosensor and manufacturing method thereof

The present invention relates to a tunneling field effect transistor biosensor using sensing of separate gate and source regions, and a method for manufacturing the same.

Recently, as process technology for nano-sized semiconductor devices has been developed, many studies have been conducted on biosensors, particularly biosensors, using the same. This is because the size of biological entities such as DNA, proteins, and viruses is similar to the size of semiconductor devices in nanometers.

Among biosensors, a sensor using a fluorescent material leveling (labeling) and light detection and a chemical method is widely used. However, this technique has problems in that it takes a lot of time to analyze the results and prepare samples, and it is expensive. For this reason, nano-sized field effect transistors (FETs) that do not require leveling and can be measured in real time are in the spotlight as biosensors.

However, general field effect transistors (FETs) such as MOSFETs cannot be manufactured to operate with a Subthreshold Swing (SS) of 60 mV/dec or less due to the physical limitations of the device. Tunneling FETs (TFETs) with high sensitivity to biomolecules by forming a current in a self-injection method are receiving much attention as biosensors.

The TFET biosensor, as shown in FIG. 1, has no gate metal in the conventional MOSFET and has a structure changed by asymmetric source/drain doping, and a biomaterial (taeget) is bound to a receptor artificially bound by digging out a part of the gate insulating film. Bio-molecules are detected on the principle that the gate potential change that occurs while the drain current changes.

Therefore, since the TFET biosensor forms a current by a carrier injection method using tunneling, it induces a large drain current difference even with a smaller gate potential change than a conventional field effect transistor represented by a MOSFET, and has excellent sensitivity.

However, the conventional TFET biosensor removes the insulating film portion existing at the source region boundary among the insulating film portion between the gate portion and the channel portion and inserts the biomaterial thereto. , and if the thickness of the gate insulating film is increased to accommodate the biomaterial, the influence of the gate on the channel is reduced, so that the characteristics of the TFET are rapidly deteriorated.

In the present invention, a space for inserting a biomaterial is separately formed in a portion adjacent to a source region, and a separate gate capable of controlling an electric field at a portion into which the biomaterial is inserted is formed to sense the biomaterial of the existing biosensor. It is a technical task to overcome the volume limit of

The technical problem of the present invention is not limited to those mentioned above, and another technical problem not mentioned will be clearly understood by those skilled in the art from the following description.

A tunneling field effect transistor biosensor according to an embodiment of the present invention forms a semiconductor substrate, a drain region and a source region formed in opposite conductivity types on the semiconductor substrate, and a channel region between the drain region and the source region when a voltage is applied. and a first gate, and a biomaterial sensing region formed with a source region interposed therebetween.

In an embodiment, a second gate configured to change the potential of the source region according to the biomaterial present in the biomaterial sensing region when a voltage is applied, wherein the biomaterial sensing region is disposed between the source region and the second gate It is characterized in that it is placed.

In an embodiment, the biosensor senses the biomaterial by changing the source potential with the amount of electric charge of the biomaterial.

In one embodiment, the biosensor is characterized in that the sensing characteristic of the biomaterial is changed by applying a voltage to the second gate.

In an embodiment, the biosensor senses the biomaterial using only a change in dielectric constant of the biomaterial by applying a voltage to the second gate.

In an embodiment, the source region has an n-type conductivity and the drain region has a p-type conductivity.

In one embodiment, the biomaterial sensing region is characterized in that it has a thickness of 10 nm to 300 nm.

A method for manufacturing a tunneling field effect transistor biosensor according to an embodiment of the present invention includes the steps of forming a drain region having a p-type conductivity type, forming a source region having an n-type conductivity type, when a voltage is applied, and a drain region and forming a first gate for forming a channel region between the source regions, and forming a biomaterial sensing region with the source region interposed therebetween.

In an embodiment, the method may further include forming a second gate configured to change the potential of the source region according to the biomaterial present in the biomaterial sensing region when a voltage is applied.

According to the present invention, it is possible to implement a biosensor that is less affected by the size of a material to be measured in a biosensor using a TFET, and improves the sensing margin through a separate gate and enables the sensing of biomaterials through dielectric constant. have

Effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

1 is a front view for explaining the structure of a conventional TFET biosensor.
2A is a cross-sectional view for explaining the structure of a TFET biosensor according to an embodiment of the present invention.
2B is a multidimensional diagram for explaining the structure of a TFET biosensor according to an embodiment of the present invention.
2C is a front view illustrating the structure of a TFET biosensor according to an embodiment of the present invention.
3A to 3D are diagrams of electrical characteristics when a voltage of 0V is applied to the second gate in the TFET biosensor according to an embodiment of the present invention.
4A to 4D are diagrams of electrical characteristics when a separate voltage is applied to the second gate in the TFET biosensor according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Although the present invention has been described with reference to the embodiment shown in the drawings, which will be described as one embodiment, the technical idea of the present invention and its core configuration and operation are not limited thereby.

2A is a cross-sectional view for explaining the structure of a TFET biosensor according to an embodiment of the present invention. Wherein the TFET 100 is fabricated on a semiconductor substrate 102, which semiconductor substrate 102 may be made of any suitable semiconductor material, for example, silicon (Si), germanium (Ge), silicon germanium (SiGe), indium. arsenide (InAs), silicon germanium (Sin), germanium tin (GeSn), silicon germanium tin (SiGeSn), or any other III-V or II-VI semiconductors.

The semiconductor substrate 102 may include doped or undoped regions. The semiconductor substrate 102 may include one or more doped regions, and if it includes multiple doped regions, these regions may be the same or may have different conductivity and doping concentrations. These doped regions are known as wells and can be used to define various device regions.

Referring back to FIG. 2A , the TFET 100 includes a drain region 104 , a source region 106 , a channel region 108 , a gate insulating film 110 , a first gate 112 , and a second gate 114 . include

The drain region 104 may include a semiconductor material doped with a p-type dopant species, and the source region 106 may include a semiconductor material doped with an n-type dopant species. Here the drain region 104 and the source region 106 are doped with opposite carriers. That is, the drain region 104 and the source region 106 are formed to have opposite conductivity types on the semiconductor substrate 102 . Here, the channel region 108 may or may not be doped for optimal performance.

The first gate is arranged to form a channel region 108 between the drain region 104 and the source region 106 when a voltage is applied. The first gate voltage greater than or equal to the threshold voltage applied to the first gate 112 switches the TFET 100 from the off state to the on state. Tunneling under the first gate occurs when a hole or electron passes through a potential barrier at the source/channel junction that is modulated by the applied first gate voltage. When the first gate voltage is low, the potential barrier at the source/channel junction is wide and tunneling is suppressed to provide a _{low I off current.} When the first gate voltage is high, the potential barrier narrows and the tunneling current is high, providing a _{high ratio of I on} /I _{off .} Here, holes or electrons tunnel between the conduction band of the channel region 108 and the valence band of the source region 106 at the source/channel junction for the TFET, and they are readily transported to the drain region 104 . Thus, TFETs enable _{higher I on} values compared to MOSFETs at lower supply voltages. The second gate 114 will be described later with reference to FIG. 2C .

2B is a multidimensional view for explaining the structure of a TFET biosensor according to an embodiment of the present invention, and FIG. 2C is a front view for explaining the structure of a TFET biosensor according to an embodiment of the present invention. Elements having the same reference numbers or names as those of FIG. 2A may operate or function in a similar manner as described above, and thus redundant descriptions will be omitted. 2B shows a channel 114 formed under the first gate 112 and its width.

Referring to FIG. 2C , the TFET includes a biomaterial sensing region 116 and a second gate 114 .

The biomaterial sensing region 116 is formed in a portion adjacent to the source region 106 . The biomaterial sensing region 116 is formed by being disposed vertically when the source region 106 is viewed from the front with the source region 106 interposed therebetween. The biomaterial sensing region 116 may be formed to insert a biomaterial to sense the biomaterial entering the sensing region.

The potential of the junction portion between the source and the channel changes according to the amount of charge and the dielectric of the biomaterial entering the biomaterial sensing region 116 , so that the current flowing through the TFET changes, thereby enabling the identification of the biomaterial. Specifically, when a biomaterial having an electric charge is attached to the source region 106 of the TFET, the potential of the source is changed, and the tunneling width existing between the source and the channel is changed to change the current of the TFET, and the current of the TFET By measuring the biomaterial, it is possible to identify the biomaterial by the genome.

In the TFET biosensor according to the present invention, unlike the conventional TFET biosensor, since the biosensing region 116 is disposed adjacent to the source region 106, a large volume of biomaterial and a low amount of charge are difficult to measure in the conventional TFET biosensor. It is possible to identify biomaterials with For example, the biomaterial sensing region may be formed to have _{a thickness D L of 10 nm to 300 nm.} Conventional TFET biosensors sense biomaterials between the gate and the channel, so it is difficult to sense large volumes of biomaterials due to the narrow width between the gates and channels. There was a problem in that the characteristics of the TFET were deteriorated because the insulating film had to be thickened by increasing the width of the TFET. However, in the TFET biosensor according to the present invention, by disposing the biosensing region 116 adjacent to the source region 106, it is possible to discriminate a large-volume biomaterial, and the insulating film existing between the gate and the channel is affected. It is also possible to maintain the advantages of TFET because it does not give

The second gate 114 is formed in a portion adjacent to the biomaterial sensing region 116 . Specifically, the second gate 114 is located above and below the biomaterial sensing region 116 located on the upper side of the biomaterial sensing region 116 when the TFET is viewed from the front. Accordingly, the biomaterial sensing region 116 is disposed between the source region 106 and the second gate 114 .

The second gate 114 may be formed of the same material as the first gate 112 in the same process, but is not limited thereto. The second gate 114 may change the potential of the source region according to the biomaterial present in the biomaterial sensing region 116 . The second gate 114 is formed to control the electric field of the biomaterial sensing region 116 into which the biomaterial is inserted, and may enable sensing of the biomaterial only with a dielectric constant. For example, the second gate 114 may input a separate voltage regardless of the first gate 112 , and this second gate voltage controls the potential of the source according to the values of the dielectric constant and charge amount of the biomaterial part. can be changed In this way, as the second gate 114 is provided, a biomaterial sensing characteristic different from the conventional TFET biosensor may be provided. That is, as the voltage is applied to the second gate voltage 114, the biomaterial can be sensed using only the change in the permittivity of the biomaterial, so it is possible to adjust the signal-to-noise ratio due to the low current and improve the sensing margin. can

3A to 3D are diagrams of electrical characteristics when a voltage of 0V is applied to the second gate in the TFET biosensor according to an embodiment of the present invention.

3A to 3D are graphs showing transfer curves according to molecular weight at different dielectric constants of molecules. The permittivity (epsilon) K in Fig. 3A is 2, the permittivity K = 5 in Fig. 3B, the permittivity K in Fig. 3C is 7, the permittivity K in Fig. 3D is 10, and in Figs. 3A to 3D, the drain voltage is 1V. , the second gate voltage is equal to 0V.

As shown, it can be seen that the drain current is changed by the charge of the biomolecules. At this time, since the drain current appears higher as the negative charge of the biomolecules is higher, it is possible to sense the biomolecules by measuring the value of the drain current, which can be seen as a result of the Poisson equation. And, it can be seen that the value of the drain current changes as the dielectric constant changes. As the dielectric constant increases, the drain current decreases. This is because as the dielectric constant increases, the effect of the source bias decreases and the tunneling path becomes wider. That is, the drain current appears high as the dielectric constant decreases and the negative charge of the biomolecules increases, and it is possible to sense what kind of material the biomolecules are based on the measured drain current. Also, although not shown, it can be confirmed that the energy band due to the potential changes and the interval of the tunneling path is changed by the bio-molecules, so that it is possible to sense the bio-molecules.

4A to 4D are electrical characteristic diagrams when a separate voltage is applied to the second gate in the TFET biosensor according to an embodiment of the present invention.

4A to 4D are graphs showing transfer curves according to molecular weight at different dielectric constants of the molecule. The permittivity (epsilon) K in Fig. 3A is 2, the permittivity K = 5 in Fig. 3B, the permittivity K in Fig. 3C is 7, the permittivity K in Fig. 3D is 10, and in Figs. 3A to 3D, the drain voltage is 1V. , the second gate voltage is equal to 0V.

4A to 4D , it can be seen that when a negative voltage is applied to the second gate, the change amount of the drain current becomes larger. In addition, it can be seen that when the dielectric constant of the molecule is large, the change is larger than when the dielectric constant is small. As described above, as the voltage is applied to the second gate, the amount of change in the drain current becomes larger, so that the sensitivity and accuracy of sensing increase. In particular, when the dielectric constant of the molecule is small, the effect can be maximized.

In addition, since the amount of change in the drain current is large as a voltage is applied to the second gate, the second gate can be used to increase the ON current (drain current). The conventional TFET has a problem in that the ON current decreases as the intermolecular gap increases. However, the TFET according to the present invention is advantageous in that the ON current can be maintained even when the intermolecular gap is large.

In another example, a method of forming a TEFT biosensor is provided, comprising: forming a drain region having a p-type conductivity type; forming a source region having an n-type conductivity type; and forming a first gate allowing a channel region to be formed between the source regions, and forming a biomaterial sensing region with the source regions interposed therebetween.

In another embodiment, the method may further include forming a second gate configured to change the potential of the source region according to the biomaterial present in the biomaterial sensing region when a voltage is applied, wherein the second gate includes the first The gate may be formed of the same material and in the same process.

Although the present invention as described above has been described with reference to the embodiments shown in the drawings, it will be understood that these are merely exemplary and that various modifications and variations of the embodiments are possible therefrom by those of ordinary skill in the art. However, such modifications should be considered to be within the technical protection scope of the present invention. Accordingly, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

100: TFET 102: semiconductor substrate
104: drain region 106: source region
108: channel region 110: gate insulating film
112: first gate 114: second gate
116: biomaterial sensing area

Claims (9)

semiconductor substrate;
a drain region and a source region formed on the semiconductor substrate to have opposite conductivity types;
a first gate configured to form a channel region between the drain region and the source region when a voltage is applied;
a biomaterial sensing region formed with the source region interposed therebetween; and
a second gate configured to change the potential of the source region according to the biomaterial present in the biomaterial sensing region when a voltage is applied;
the biomaterial sensing region is disposed between the source region and the second gate;
The source region has an n-type conductivity and the drain region has a p-type conductivity,
A voltage is applied to the second gate and the biomaterial is sensed using a change in the dielectric constant of the biomaterial. When a negative voltage is applied to the second gate, the drain current is greater than when no voltage is applied. A tunneling field effect transistor biosensor, characterized in that generated. delete According to claim 1,
The biosensor is a tunneling field effect transistor biosensor, characterized in that sensing the biomaterial by changing the source potential with the amount of charge of the biomaterial. delete delete delete According to claim 1,
The biomaterial sensing region is characterized in that it has a thickness of 10nm to 300nm, tunneling field effect transistor biosensor. forming a drain region having a p-type conductivity;
forming a source region having an n-type conductivity;
forming a first gate allowing a channel region to be formed between the drain region and the source region when a voltage is applied;
forming a biomaterial sensing region with the source region interposed therebetween; and
forming a second gate to change the potential of the source region according to the biomaterial present in the biomaterial sensing region when a voltage is applied;
the biomaterial sensing region is disposed between the source region and the second gate;
A voltage is applied to the second gate and the biomaterial is sensed using a change in the dielectric constant of the biomaterial. When a negative voltage is applied to the second gate, the drain current is greater than when no voltage is applied. A method of manufacturing a tunneling field effect transistor biosensor, characterized in that it occurs. delete

Images