JP2003332573A - Gate insulating transistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gate insulating transistor having a ferroelectric dielectric layer in a gate insulator. <P>SOLUTION: A heat detector is provided with a conversion layer constituted of a semiconductor yttrium barium copper oxide, and this conversion layer with sensitivity to radiation at room temperature is configured to detect an infrared ray. In the embodiment of a gate insulation type transistor, a gate insulating layer is formed of a ferroelectric semiconductor yttrium barium copper oxide, and the capacity of the transistor is increased, or the transistor is latched in accordance with the polarizing direction of the ferroelectric dielectric layer. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared detector, and more particularly to a gate insulation type transistor,
In particular, it relates to a gate insulation transistor having a ferroelectric substance in the gate insulation.

[0002]

Radiation detectors are devices that produce an output signal that is dependent on the amount of radiation incident on the active region of the detector, among which infrared detectors are those that emit radiation in the infrared region of the electromagnetic spectrum. It is a detector that responds. There are two types of infrared detectors: heat detectors and photon detectors.

Photon detectors work based on the number of photons incident on the conversion region of the detector. Photon detectors make use of the direct relationship between electrons and photons and are more sensitive than thermal detectors. However, in order to obtain high sensitivity with a photon detector, there is a problem that it must be operated at a low temperature and cooling is required.

The thermal detector operates on the basis of a change in the temperature of the conversion region of the detector due to the absorption of the radiation to be detected and produces an output signal in proportion to the temperature of the conversion region. In general, absorption of radiation occurs over a wide wavelength range, so that the thermal detector responds over a wide wavelength range. However, thermal detectors usually have lower sensitivity and slower response speed than photon detectors.

The bolometer has a conversion region whose resistance value changes depending on temperature. The voltage response of a bolometer is a measure of the effectiveness of the bolometer in detecting radiation, and the voltage response of a bolometer is defined as:

[Equation 1] Where I _b is the bias current through the conversion region of the detector,
R is the electrical resistance of the conversion region of the detector, η is the absorption rate of electromagnetic radiation incident on the surface of the conversion region of the detector, G is the thermal conductivity from the conversion region of the detector, and ω is the conversion region of the detector. The angular modulation frequency of incident electromagnetic radiation, T is the temperature of the conversion region, and γ is the thermal time coefficient of the conversion region of the detector. γ is C /
Equal to G, where C is the heat capacity of the conversion region of the detector.

The standardized (normalized) bolometer voltage detection rate D ^* _VB is another measure of sensitivity and is defined as follows:

[Equation 2] Here, Δf represents the frequency bandwidth associated with the bolometer (generally the bandwidth of the amplifier), and V _n represents the noise voltage of the output signal of the bolometer. Therefore, in order to obtain a high detection rate, (1) the noise voltage V _n is low,
(2) It is necessary that the response rate R _VP is high.

The pyroelectric detector is a thermal detector incorporating a pyroelectric material as the conversion material. Pyroelectric materials have an electric polarization and have a dielectric constant that is a function of temperature. As the temperature of the pyroelectric material changes, the electrical polarization of the pyroelectric material changes. Due to the pyroelectric effect, insulating pyroelectric materials generate surface charges that are proportional to their electrical polarization. The pyroelectric detector can be composed of a capacitor using a pyroelectric material as the dielectric.

Response of the pyroelectric detector R_VPA pyroelectric detector
Ratio of the output voltage of the laser to the power of radiation incident on the pyroelectric detector
Is defined as Standardized voltage detection for pyroelectric detectors
Rate D ^* _VPIs defined as follows.

[Equation 3] Where R _VP is the voltage response of the pyroelectric detector, V _n is the noise voltage of the output signal of the pyroelectric detector, Δf is the frequency bandwidth associated with the pyroelectric detector (generally the bandwidth of the amplifier), A indicates the surface area of the pyroelectric material heated by the incident radiant energy.

Another method for assessing the sensitivity of a pyroelectric detector is:
It is the minimum pyroelectric sensitivity M _T defined by the following equation.

[Equation 4] Here, C _P is the specific heat of the heated portion of the pyroelectric detector, ρ is the density of the heated portion of the pyroelectric detector, ε _r is the relative dielectric constant of the pyroelectric material (ε = ε _r × ε ₀ , and ε ₀ is the dielectric constant of the vacuum), δ =
(Σ / (ω · ε)) ^1/2 . Further, σ is the electrical conductivity of the pyroelectric material, and ω is the angular frequency at which the radiation incident on the pyroelectric detector is modulated. The change in temperature of the pyroelectric material can be measured based on the change in the dielectric constant and the electrical polarization of the pyroelectric material or its layer.

A change in the electrical polarization of the pyroelectric material causes a pyroelectric current, which is caused by a change in the surface charge of the pyroelectric material per unit time caused by a change in the degree of the electric polarization of the pyroelectric layer. It is determined.

In conventional thermal detectors, ie bolometers and pyroelectric detectors, the infrared detection rate D ^* was less than 10 ¹⁰ . Therefore, it has higher sensitivity, less noise,
There is still a strong demand for heat detectors with high detection rates.

Most of the conventional infrared detecting materials have used conversion materials that are not suitable for the thin film deposition technique. For example, the barium strontium titanate converter used as a pyroelectric converter first forms a bulk of ceramic,
The bulk is then mechanically thinned to produce the heat capacity.

Therefore, there is a need for conversion materials compatible with thin film deposition techniques. Furthermore, using the vacuum deposition method,
More preferred is a conversion material that can be formed into a thin layer or film so that the substrate is not heated too much (ie, a thickness of 2-3 microns).

Although not relevant to the sensor per se, the technique of which the present invention is simultaneously concerned is gate-insulated transistor technology. A transistor serves to switch between a conductive "open" state and a non-conductive "closed" state by opening and closing a semiconductor conduction channel. The gate-insulated transistor uses the voltage supplied to the gate electrode to change the potential of the conduction channel of the semiconductor. Charge carriers (ie, electrons or holes) when an electromotive force is present along the conduction channel due to the potential applied to the conduction channel by the gate electrode.
Is determined to pass through the conduction channel. Thus, the voltage on the gate electrode determines whether the conduction channel is in a conductive "open" state or a non-conductive "closed" state.

In general, in order to keep the potential of the conduction channel and, in particular, the switching state (open or closed) of the transistor constant, the voltage applied to the gate electrode must be kept constant. Further, the gate electrode is insulated from the conduction channel of the transistor by an electric insulating layer (so-called gate insulating layer).

If the gate insulating material comprises a ferroelectric layer, the polarization of the ferroelectric layer will affect the potential of the conduction channel. Therefore, it is possible to switch the conduction state of the channel of the transistor by changing the polarization state of the ferroelectric layer.

The polarization of the ferroelectric layer can also be changed by applying a voltage pulse of an appropriate polarity to the gate electrode to produce an electric field in the ferromagnetic layer. When a voltage pulse is applied to the gate electrode, the ferroelectric state of the ferroelectric gate insulator switches, causing a change in the electrical polarization of the ferroelectric gate. This change in electrical polarization changes the potential of the conduction channel of the transistor.

A gate insulation type transistor having a ferroelectric insulation layer is also demanded as a memory cell.
The ferroelectric layer in the gate insulator attracts or repels charge carriers in the conduction channel, thus providing a mechanism for storing charges. The charge storage capacity of a gate insulating transistor having a ferroelectric insulating layer in the gate insulator is larger than that of a gate insulating transistor having no ferroelectric layer in the gate insulator.

However, a ferroelectric material known as a ferroelectric material that can be deposited on a commonly used semiconductor such as silicon has a relatively high deposition temperature. Such a high vapor deposition temperature is harmful to the structure for forming an element on a commonly used semiconductor substrate such as a silicon substrate. That is, there has been a long-felt need for a ferroelectric material that can be used as a ferroelectric layer in a gate insulator in a transistor such as a silicon base and can be adapted to a commonly used semiconductor process technology.

[0020]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat detector which has high detection sensitivity and does not require cooling. Another object of the present invention is to provide a bolometer having high detection sensitivity and requiring no cooling. Another object of the present invention is to provide a pyroelectric detector that has high detection sensitivity and does not require cooling. Another object of the present invention is to provide a gate insulation transistor having a ferroelectric layer in the gate insulation.

[0021]

SUMMARY OF THE INVENTION The present invention provides a bolometer and pyroelectric detector that includes a transducer and operates at room temperature. These converters have a resistivity at 20 ° C. of at least 0.1 Ωcm, a rate of change in resistance with temperature at 20 ° C. of at least 0.4% / ° C., more preferably at least 2.5% / ° C. At least 5
0, change in dielectric constant with temperature is at least 0.20 / ℃
Is.

The present invention also provides a transistor having a gate insulator. The gate insulator comprises a layer of material that is a ferroelectric at room temperature and is capable of being deposited at temperatures compatible with conventional semiconductor processes.

The layer of material provided by the present invention is formed essentially from yttrium, other rare earths, lanthanum, or combinations thereof; barium, strontium, calcium, or combinations thereof; copper, and oxygen. It has one or more solid phases. Hereinafter, "yttrium, other rare earths, lanthanum, or a combination thereof", "barium, strontium, calcium, or a combination thereof", "copper", and "oxygen" are referred to as "YBCO". This solid phase is crystalline or amorphous. Then, the solid layer of the material exhibits semiconductor-like resistance-temperature characteristics, and its resistivity is
Metal or orthorhombic YBa ₂ which is crystalline and has conductivity
It is higher than Cu ₃ O ₇ and the resistance of the layer increases with increasing temperature. Since lanthanum and rare earth elements replace Y in the YBCO phase, some or all of yttrium in the YBCO phase may be replaced by these elements. These rare earth elements include Ce, Pr, Nd, Pm and S.
m, Eu, Gd, Tb, Dy, Ho, Er, Tm, Y
b and Lu are included.

The resistivity of the YBCO layer at 20 ° C. is
0.1 Ωcm or more, more preferably 1.0 Ωcm
That is all. The preferable range of the resistivity of the YBCO layer is 1.
It is 4 to 15 Ωcm. The rate of change of the resistance value with the temperature change of the YBCO layer at 20 ° C. is 0.4% / ° C. or more, and more preferably 2.0% / ° C. or more. The rate of change of resistance value with temperature change means 1 / R × dR / dT. Here, R is resistance and T is temperature. Regarding the YBCO layer of the present invention, the rate of change in the resistance value with the actual temperature change was 0.4 to 3.9% / ° C. Due to advances in material processing, a YBCO layer having a resistance change rate of 5 to 10% / ° C. with temperature change at 20 ° C. will eventually be obtained. The dielectric constant of the layer of the material according to the present invention at 20 ° C. is 50 or more, more preferably 50 or more and 87 or less. The change in permittivity with temperature at 20 ° C is 0.2 / ° C or more, and more preferably 0.5 /
℃ or above.

The solid phase in the YBCO layer according to the present invention has, firstly, a semiconductor phase in the YBCO phase diagram, especially a tetragonal Y ₁ Ba ₂ Cu ₃ O _{6 + x} phase (0≤x <0. .5),
It contains a Y ₂ BaCuO _{5 + δ} phase (−0.5 <δ <0.5) and a YBa ₃ Cu ₂ O _x phase.

Further, the YBCO layer according to the present invention comprises a material
A small amount of YBCO metal crystals, which is disadvantageous in terms of characteristics
Phase or YBCO polycrystalline phase may be included. here
"Metallicity" means that it is less than 0.05 Ωcm at 20 ° C.
It has a resistivity and shows that the resistance decreases as the temperature decreases.
means. As a metal phase contained in the YBCO phase structure
Is Y₁Ba_TwoCu_ThreeO_7-xPhase (0 ≦ x <0.5),
Y₁Ba_TwoCu_3.5O _{7 + x}Phase (0 <x ≦ 1), Y₁
Ba_TwoCu_FourO_{8 + x}Phase (0 ≦ x ≦ 1), Y_TwoBa₁C
u₁O₅Phase, and Y₁Ba_ThreeCu_TwoO_xPhase
It The resistivity of each of these metal phases is at 20 ° C.
Is less than about 0.05 Ωcm.

Since the resistivity of the conductive phase is generally much lower than the resistivity of the semiconductor phase of YBCO, the YBCO of the present invention.
It is desirable that the fractional volume of the conductive crystalline phase in the layer be sufficiently small so as not to form a continuous conductive path in the YBCO layer. Therefore, generally, the fraction volume of the conductive phase in the YBCO layer needs to be less than 20%, more preferably less than 5%. YB according to the present invention
In the CO material, the most preferable content rate of the conductive phase is 0%
Is. On the contrary, the fraction volume of the semiconductor phase in the YBCO layer needs to be at least 80% or more of the whole, more preferably 95% or more, and most preferably 100%.

An important point in the present invention is that the YBCO layer can be coated (deposited) on the substrate without heating the substrate and has the above-mentioned resistivity, dielectric constant and temperature resistivity. is there. If the substrate is not heated during vapor deposition, the substrate temperature during vapor deposition can always be kept below 100 ° C. The YBCO layer can be deposited by a reactive co-evaporation method, a sputtering method, a pulsed laser deposition method, or the like. Further, the YBCO layer is formed by chemical vapor deposition (CVD
Method).

Although it is possible to heat the substrate during vapor deposition in order to increase the crystallinity of the vapor deposited layer, it is not always necessary to heat the substrate during vapor deposition in the present invention.

After deposition of the layer, it is possible to adjust the oxygen composition of the YBCO layer by annealing the layer under controlled oxygen partial pressure. By performing the annealing treatment in the state where the oxygen partial pressure is low after vapor deposition, the YBCO
It is also possible to remove oxygen from the layer, which allows Y
A semiconductor layer of BCO is obtained. However, the annealing treatment is not always necessary in the present invention. As described above, according to the present invention, it is possible to deposit the YBCO layer at a temperature suitable for a commonly used semiconductor process. The obtained YBCO layer has high resistivity, high temperature resistivity,
It is suitable for bolometers. Moreover, since this YBCO layer has a high dielectric constant and a high temperature dielectric constant, it is also suitable for a pyroelectric detector. Further, since this YBCO layer has ferroelectricity, it can be suitably applied to a transistor.

Further, the YBCO thin film that is vapor-deposited at room temperature and is not annealed after vapor deposition has a behavior as a semiconductor, has a fine amorphous structure, and has high detection sensitivity and high responsiveness. .

[0032]

The invention will be appreciated and its advantages will be readily appreciated by the following drawings and the following detailed description.

The present invention will be described in detail below with reference to the drawings. Throughout the drawings, the same reference numerals indicate the same or corresponding parts. 1A and 1B show a bolometer B, which comprises a support layer 1 and a crystalline or polycrystalline semiconductor YBCO layer 2 according to the invention formed on this support layer 1. is doing. Two conductor electrodes 3 and 3 are provided on the YBCO layer 2. The support layer 1, the YBCO layer 2, and the conductor electrodes 3 and 3 form an integrated conversion structure 42. Preferably, the conversion structure 42 is supported by a plurality of connection leads 4, which are connected to the electrodes 3, 3 made of a conductor.
Are electrically connected to the conductor columns 5 and 5. The height of the conductor columns 5, 5 is greater than the combined height of the support layer 1, the YBCO layer 2, and the conductor electrode 3, whereby the conversion structure 42 floats above the upper surface of the substrate 6. Suspended in the state. The base 6 may be the semiconductor substrate of the integrated circuit 7. Alternatively, the integrated circuit 7 may be attached to the base 6. Integrated circuit 7 is YBCO layer 2
Is electrically connected to the YBCO layer 2 from the integrated circuit 7 via electric conductor columns 5 and 5. Above the exposed surface of the YBCO layer 2,
A shutter or chopper S is provided as schematically shown, by means of which the YBCO layer 2 can be turned on and off. The support layer 1 is an insulator.

The integral conversion structure 42 is arranged away from the base 6 so as to be thermally isolated, thereby improving the response speed. Preferably, the conversion structure 4
The thickness of 2 (that is, the total thickness of the support layer 1, the YBCO layer 2, and the conductor electrode 3) is smaller than 10 μm, and more preferably smaller than 5 μm. This is to reduce the heat capacity and improve the thermal response to radiation.

FIG. 1B is a plan view of the upper surface of the integrated conversion structure 42, showing the upper surface of the support layer 1, the meandering pattern portion formed by the YBCO layer 2, and the upper surfaces of the conductor electrodes 3 and 3. It is shown.

The integrated circuit 7 is electrically connected to the YBCO layer 2 through the conductive support columns 5 and 5, and has means for measuring the electric resistance of the YBCO layer 2. The resistance measuring means comprises means for applying a voltage across the YBCO layer 2 and thereby means for measuring the current flowing through the YBCO layer 2 or for supplying a current across the YBCO layer 2. And means for measuring the voltage drop across the YBCO layer 2. The resistance measuring means also comprises means for dividing the voltage by the current.

The integral conversion structure 42 need not be connected to the base body 6 via the conductive posts 5,5. For connecting the conversion structure 42 and the integrated circuit 7, the conductor support pillars 5,
If 5 is not used, the stanchion need not be a conductor. The stanchions are for thermally isolating the conversion structure from the substrate 6. It is preferable that the conductive support columns 5 and 5 project from the substrate 6 by at least 100 nm.

The means for measuring the electrical resistance of the YBCO layer 2 need not be provided in the integrated circuit 7 or even on the substrate 6. The support layer 1 may be formed of, for example, silicon nitride, strontium titanate, or yttrium-stabilized zirconia.

2A and 2B are cross-sectional views of pyroelectric detector P, which is an integral conversion structure 42.
a and an integrated circuit 7a. Conversion structure 42
a has a support layer 1a having conductivity and a YBCO layer 2 deposited on the support layer 1a. Conductor electrodes 3a and 3a are formed on the YBCO layer 2. A chopper for selectively blocking infrared radiation is provided above the exposed surface of the YBCO layer 2. These conductor electrodes 3
a and 3a are Y as a dielectric together with the conductive support layer 1.
A capacitor is formed by sandwiching the BCO layer 2. The areas of the conductor electrodes 3a, 3a may be the same or different, and in that case, the capacitances of the capacitors formed by the conductor electrodes 3a are different from each other. In the illustrated embodiment, two capacitors are formed, but one capacitor is sufficient to form the pyroelectric detector.

FIG. 2B shows two conductive electrodes 3a, 3a.
And an equivalent circuit of the circuit formed by the conductive support layer 1, this equivalent circuit comprising two capacitors 23, 2,
It consists of 4.

The integrated circuit 7a corresponds to Y in the conversion structure 42a.
Means are provided for measuring the pyroelectric current caused by the change in electrical polarization of the BCO layer 2. Conversion structure 42
The means for measuring the pyroelectric current of a is a conductor electrode 3
a, 3a for supplying an alternating current or an alternating voltage (that is, an alternating current source or an alternating voltage source), and means for measuring the alternating voltage or the alternating current produced thereby. In this embodiment, two capacitors are formed by the two conductor electrodes 3a and 3a. However, when only one capacitor is formed, one electrode is sufficient, and the pyroelectric current in that case is sufficient. The measuring means may supply an alternating current or an alternating voltage to one conductor electrode 3a and measure the voltage or current through one conductor electrode 3a. No bias voltage needs to be applied to measure pyroelectric current.

The conversion structure 42a preferably has a thickness of less than 10 μm, more preferably less than 5 μm in order to reduce its heat capacity. Most preferably, the thickness of the conversion structure 42a is less than 1 μm.

One modification of the conversion structure 42a includes a connecting lead connected to the conductive support layer 1a instead of the one conductive electrode 3a, and the one conductive electrode 3a is unnecessary. Is. The change in the dielectric constant of the YBCO layer 2a with temperature is preferably at least 0.2 / ° C at 20 ° C.

FIG. 3 shows a cross section of a transistor 32, which is a Y gate insulator.
It has a BCO layer 36 and a field insulating layer 34 made of silicon dioxide, which are provided on an n-type semiconductor substrate 33. The source electrode 35 and the drain electrode 39 are connected to the p-type source connection region 35a and the p-type drain connection region 39a, respectively, which are spaced apart from each other, and Y is provided between the source electrode 35 and the drain electrode 39.
The BCO layer 36 and the gate electrode 37 are arranged.
A transistor channel 38 is formed below the gate electrode 37 and the gate insulating YBCO layer 36.
The gate insulating YBCO layer 36 is a ferroelectric substance having electric polarization, and the direction of the electric polarization is oriented along the first direction by applying a first voltage pulse larger than the first voltage to the gate electrode. At the same time, a second voltage pulse having a polarity opposite to that of the first voltage and larger than the second voltage is applied to the gate electrode so that the gate electrode can be oriented in the direction opposite to the first direction. There is. However, being able to reverse the polarization direction of the ferroelectric YBCO layer 36 is not necessary to increase the charge storage of the transistor T. If the transistor T constitutes the charge storage capacitor of the memory cell, the stored charge is increased by the presence of the YBCO layer 36.

The YBCO layer and integrated conversion structure according to the present invention are also compatible with conventional semiconductor processing techniques using positive or negative photoresist and lift-off techniques.

The integrated conversion structure of the present invention can also be formed by conventional thin film process techniques using photoresist etching or lift-off techniques.

A method of manufacturing the suspended integrated conversion structure will be described with reference to FIGS. 4A to 4D. The integrated conversion structure shown in FIG. 4C can be used as a bolometer according to the present invention. 4A to 4D show a method of manufacturing an integrated conversion structure for a bolometer according to the present invention, the same method is used to manufacture the integrated conversion structure for a pyroelectric detector according to the present invention. It is also possible to manufacture.

As shown in FIG. 4A, first, on a silicon substrate (base) 100, first silicon nitride (Si ₃ N ₄ ) is formed.
Layer, first yttrium-stabilized zirconia layer, YBCO
Layer and a second yttrium-stabilized zirconia layer are sequentially deposited, and the deposited layer is patterned to form a silicon nitride layer 1
01, first yttrium-stabilized zirconia layer 102, Y
A multi-layer structure 105 including the BCO layer 103 and the second yttrium-stabilized zirconia layer 104 is formed. The silicon nitride layer 101, the first yttrium-stabilized zirconia layer 102, the YBCO layer 103, and the second yttrium-stabilized zirconia layer 104 may be etched or formed by ion milling.

Next, a second silicon nitride layer 106 is deposited on the intermediate body shown in FIG. 4A, and the second silicon nitride layer 106 is patterned to remove a part of the second yttrium-stabilized zirconia layer 104. Expose. The exposed portion of the second yttrium-stabilized zirconia layer 104 is etched to form the connection notch 107. Ion milling can be used to etch the exposed portions of the second yttrium-stabilized zirconia layer 104. Next, as shown in FIG. 4B, a metal layer is deposited on the second silicon nitride layer 106, and the metal layer is patterned to form a metal lead 108.

After the metal leads 108 are formed, the second silicon nitride layer 106 is patterned and etched to
A groove 109 reaching the silicon substrate 100 is formed. Second
Plasma etching can be used to etch the silicon nitride layer 106.

FIG. 4D shows the multi-layer structure 105 of the conversion structure.
The arrangement of the groove 109 with respect to is shown. The groove 109 substantially surrounds the multilayer structure 105, but a part of the second silicon nitride layer 106 is left to be the supporting portions 111 and 111. The groove 109 penetrates the second silicon nitride layer 106,
The surface of the silicon substrate 100 is reached. Once the grooves 109 are formed, the silicon substrate 10 is passed through these grooves 109.
Etching is performed from the surface of 0 to the lower side of the multilayer structure 105, and a portion below the multilayer structure 105 is hollowed out to form a cavity 110. Similarly, since the lower sides of the supporting portions 111, 111 are also hollowed out by etching, the integrated conversion structure 112 is suspended by the supporting portions 111, 111. The supporting portions 111, 111 are the second silicon nitride layer 1
06, which is supported by the unetched columnar portion 113 of the silicon substrate 100. The columnar portion 113 has the original surface of the silicon substrate 100.

The number of supporting parts may be one. However, it is more beneficial to form the pair of support parts 111, 111 as in the embodiment of FIG. 4D. An etching solution that selectively dissolves the silicon substrate 100 does not dissolve silicon nitride. For example, a potassium hydroxide solution is a silicon substrate 100.
Can be used for etching. Forming the cavity 110 forms a suspended integral conversion structure, as shown in FIG. 4C.

The substrate on which the integrated conversion structure is formed is not limited to silicon. For example, the substrate is III-
It may be V semiconductor or polyamide.

5A to 5D are cross-sectional views showing various stages in the manufacturing process of the transistor T.

FIG. 5A shows an n-type semiconductor substrate 33, on which a source connection region 35a and a drain connection region 39a and a silicon dioxide field oxide layer 34a are formed. Field oxide layer 34
a is patterned, and the p-type source connection region 35 is formed.
Doping of the a and p type drain connection regions 39a is possible. Then the field oxide layer is grown again.

FIG. 5B shows the regrown field oxide layer 34 on the n-type substrate 33. Next, the field oxide layer 34 is removed from the gate region and the YBCO layer 36 is removed.
a is deposited on the structure to form a YBCO gate insulator.

FIG. 5C shows a state in which the YBCO layer 36a covers the structure. Next, YB other than the gate region
The CO layer 36a is removed, connection notches for forming the source electrode 35 and the drain electrode 39 are formed, and a metal layer is vapor-deposited and patterned to form the source electrode 35,
A metal wire portion for connecting the drain electrode 39 and the transistor T of FIG. 5D is formed.

<Experimental Example 1> (Bolometer) An integrated bolometer conversion structure was formed by the following manufacturing method. Magnesium oxide having a thickness of 1000 angstrom was formed on an n-type (100) silicon substrate by the RF sputtering method.

Next, on the magnesium oxide layer, Y ₁ Ba was formed.
_A YBCO layer was formed using a sputtering target made of ₂ Cu ₃ O ₇ under the conditions of 150 watts, 7 hours, and 10 millitorr of argon gas. The thickness of the YBCO layer was 500 nm. The substrate was not heated during the deposition of the YBCO layer.

Next, the positive photoresist "Mic
roposite 400-27 photoresist "
Spin drop on the BCO layer at 3000 rpm and
It was dried for 0 seconds. The photoresist was lightly baked and hardened under heating conditions of 90 ° C. for 30 minutes, and then exposed to ultraviolet light for 6 seconds using a pattern corresponding to the exposed region of the YBCO layer,
The photoresist in the non-electrode area was removed by immersing in the developer “MF319 developer”. After development, the photoresist was heated at 125 ° C. for 30 minutes to fully cure it.

Aluminum etching was performed for 1 to 1/2 minutes to remove the exposed YBCO. The remaining photoresist was removed from the YBCO layer and the connection lead was connected to the YBCO layer.

The resistance-temperature characteristics of Experimental Example 1 were measured using the system shown in FIG. FIG. 6 shows a semiconductor YBCO layer 8
It is a block diagram for measuring the resistance-temperature characteristics of
The YBCO layer 8 is set in the cryostat 9.
The YBCO layer 8 is connected to the DC current / voltage supply monitoring device via the DC leads 10 and 10 '. A temperature controller 12 is connected to the YBCO layer 8 via a plurality of leads 13, and the leads 13 are thermally coupled to the YBCO layer 8. The temperature controller 12 is connected to the YB through the lead 13.
The heat of the CO layer 8 is measured by a temperature sensor (not shown), and an electric current is supplied to the heater arranged near the YBCO layer 8 through the lead 13. A computer 15 is connected to the temperature controller 12 and the DC voltage / current source monitor 11, and the computer 15 adjusts the temperature of the YBCO layer 8 and receives the data from the DC voltage / current source monitor 11. 15 is capable of displaying resistance versus temperature.

The resistance value of the YBCO layer of Experimental Example 1 was 20 ° C.
Was 4 × 10 ⁶ Ω. The width of the YBCO layer is 0.
The thickness of the YBCO layer was 1 mm, the length of the YBCO layer was 11 mm, and the thickness of the YBCO layer was 500 nm. Therefore, the YBC of Experimental Example 1
The resistivity of the O layer is 1.8 Ωcm.

FIG. 7 shows the temperature dependence of the resistance value of the sample of Experimental Example 1 when measured while changing the temperature using two kinds of bias currents. At any temperature, the resistance value rapidly decreases from 7 × 10 ⁶ Ω at 0 ° C. to 2 × 10 ⁶ Ω at 50 ° C. The change in resistance value per 1 ° C. is 0.1 × 10 ⁶ Ω. The resistivity of the sample is 1.46 to 1.
It was 65 Ωcm. The measured noise voltage was 10 ⁻⁵ V / Hz ^1/2 at 30 Hz. The rate of change of the resistance value with the temperature change of the YBCO layer is 3.5% / ° C., and the calculated detection degree is 10 ⁹ .

The composition of the YBCO layer of the monolithic structure of Experimental Example 1 was subjected to electron probe analysis using standard YBCO on magnesium oxide. As a result, YBa _1.44 Cu _{1.65 was obtained.}
O _{4 .} It turned out to be ₅₉ . The first phase, shown by X-ray diffraction, is a tetragonal phase, stoichiometrically YBa
₂ Cu ₃ O _6.5 , and this tetragonal phase (110)
It had a peak at d = 2.72 corresponding to the X-ray diffraction line.

Experimental Example 2 (Pyroelectric Detector) An integrated pyroelectric conversion structure was formed by the following steps. n
A bottom electrode made of niobium having a thickness of 3000 angstrom was vapor-deposited on the upper surface of the mold (100) silicon substrate.

Next, on the bottom electrode made of niobium, 10
Y ₁ Ba ₂ Cu ₃ O under an argon atmosphere of millitorr
Using a sputtering target of No. ₇ , power of 150W
A YBCO layer having a thickness of 5000 Å was sputtered for 6 hours under the above conditions. The deposited layer was annealed in vacuum at 500 ° C. for 2 hours to remove oxygen from the deposited layer.

Next, a 3000 angstrom aluminum layer was formed on the YBCO layer by RF sputtering in an atmosphere of 15 mTorr argon for 10 minutes.

"Microposit 400-27"
A photoresist was spin-dropped on the vapor deposition layer at 3000 rpm and dried for 30 seconds. 90 layers deposited
It was lightly cured at 30 ° C. for 30 minutes and then exposed to UV light for 6 seconds. The photoresist was immersed in a developer "MF319" for 1 minute to form a plurality of photoresist circles having a diameter of 0.9 mm on aluminum. After development, the photoresist is kept at 125 ° C for 3
Heated for 0 minutes to fully cure. The layer was immersed in an aluminum etchant for 3 minutes to remove exposed aluminum and exposed YBCO. As a result, a cylindrical capacitor could be formed, and this capacitor had the YBCO layer according to the present invention between the lower niobium electrode and the upper aluminum electrode.

The capacitance of the capacitor of Experimental Example 2 versus temperature was measured using the apparatus of FIG. FIG. 8 is a block diagram for measuring the capacitance-temperature characteristic of a capacitor having the YBCO layer 25 as a dielectric. The condenser having the YBCO layer 25 is a cryostat (incubator).
26, which is a current lead 27.
L via a, 27b and voltage leads 27c, 27d
It is connected to the CR meter 30. Leads 27a, 2
7d is connected to an aluminum electrode and leads 27b, 2
7c is connected to the niobium electrode. LCR meter 3
0 generates an alternating current or voltage and measures the alternating voltage or current. A temperature controller 28 is connected to the YBCO sample 25 via a lead 29. YBCO layer 2
A temperature sensor (not shown) is thermally coupled to 5, and supplies temperature data to the temperature controller 28. The temperature regulator 28 supplies current to a resistance heater (not shown) that is thermally coupled to the YBCO layer 25 via leads 29.
The temperature obtained by the temperature regulator 28 is controlled by the computer 31 which transfers voltage and current data from the LCR meter 30, and the capacitance vs. temperature of the YBCO layer 25 is calculated and displayed.

FIG. 9 is a graph showing the relationship between the capacitance per unit area and the temperature of Experimental Example 2 measured using the system of FIG. The capacitance is between 0 and 30 ° C,
The change was about 20 nf / cm ² . Therefore, the rate of change in capacity per temperature is 0.67 nf / cm ² / ° C. The three types of curves in FIG. 9 are 150 Hz, 20
The case of 0 Hz and 250 Hz is shown. However, the capacity change rate per temperature is substantially the same at any of the three frequencies.

The composition of the YBCO layer of the capacitor of Experimental Example 2 was YBa ₂ Cu ₃ O _6.45 by electron probe analysis using the YBCO standard on magnesium oxide and the YBCO standard on lanthanum arsinate. all right. The first phase shown by X-ray diffraction of the YBCO layer of the capacitor of Experimental Example 2 is a tetragonal phase, the lattice constants a and b are 3.8 angstrom, and the lattice constant c is 1.
It was 1.75 angstroms. The first X-ray diffraction peak is d = 2.35, which is YBa ₂ Cu ₃ O.
A tetragonal YBCO phase having a composition of _6.5 (005)
It corresponded to the X-ray diffraction line. 200 at about 20 ° C
The relative permittivity of the YBCO layer at 87 Hz is about 20 ° C.
The change in dielectric constant with temperature was 0.275 / ° C.

<Experimental Example 3> (Bolometer) A bolometer was produced by using a manufacturing method substantially similar to that of the bolometer of Experimental Example 1, except for changing the following points.
A YBCO layer having a c-axis perpendicular to the substrate was formed on the (100) lanthanum aluminate substrate using a pulse laser deposition method. The YBCO layer was then annealed in vacuum at 500 ° C. for 2 hours. According to the electron probe analysis, the metal of the YBCO layer was stoichiometrically
It was Ba ₂ Cu ₃ . The resistivity of the YBCO layer is about 12.
It was 7 Ωcm. At about 20 ° C., the change in resistance was about 6000 Ω / ° C. The measured noise voltage was 10 ⁻⁵ V / Hz ^1/2 at 30 Hz. The rate of change of the resistance value with the temperature change of the YBCO layer is 2.
31% / ° C. and the calculated detectivity was 9 × 10 ⁹ .

Experimental Example 4 (bolometer) This experimental example relates to an amorphous YBCO thin film. The YBCO thin film was formed by vapor deposition by the above-described method, except that the substrate was not heated during vapor deposition and annealing was not performed after vapor deposition. These thin films behave like semiconductors, have an amorphous microstructure,
It has high sensitivity and responsiveness. The amorphous microstructure is
It was formed because the annealing that promotes recrystallization of the polycrystalline YBCO thin film was omitted. The elimination of annealing is preferred as it facilitates combining with other thin film technologies such as CMOS technology. The composition of the amorphous YBCO thin film was measured by Rutherford backscattering spectroscopy, and as a result, the element ratio of Y: Ba: Cu: O was 1: 1.29: 2.
It was 91: 7.05 to 1: 2.10: 3.44: 9.82. The preferable stoichiometric composition ratio is Y ₁ Ba.
_{(1.2 to 2.5)} and _{Cu (2. 5~3.5) O x,} has an amorphous microstructure. Preferably, x is 7.05 to 9.82. However, x may be substantially wider than the range shown here, since it cannot be accurately determined by the Rutherford backscatter technique.

Amorphous thin films were determined to be amorphous using 2θ and angle of incidence techniques. However, according to Raman spectroscopy, a broad peak was seen at 571 cm ⁻¹ . The rate of change in resistance of this amorphous thin film with temperature was about 3.5% / ° C. at 20 ° C., indicating good radiation response characteristics. The resistivity of the amorphous thin film was greater than about 0.1 Ωcm at 20 ° C. Therefore, these amorphous thin films could be an alternative to the crystalline thin films described above and the disclosed bolometer structure.

As is apparent from the above disclosure, the present invention can be variously modified. Therefore, the present invention is not limited to the examples described above.

[Brief description of drawings]

FIG. 1A is a side cross-sectional view showing a bolometer incorporating a YBCO material layer as an embodiment of the present invention.

FIG. 1B is a plan view showing the structure of the integrated detector shown in FIG. 1A.

FIG. 2A is a side sectional view showing a pyroelectric detector incorporating a YBCO material layer according to another embodiment of the present invention.

2B is a schematic diagram showing an equivalent circuit of the integrated detector of FIG. 2A. FIG.

FIG. 3 is a side sectional view of a semiconductor transistor having a YBCO material layer incorporated in a gate insulator according to another embodiment of the present invention.

FIG. 4A is a partially cutaway side view showing the structure of an intermediate in the manufacturing process of a suspended integrated transducer structure.

FIG. 4B is a side view, partially broken away, showing the structure of an intermediate in the manufacturing process of a suspended integrated transducer structure.

FIG. 4C is a partially cutaway side view showing the structure of an intermediate in the manufacturing process of a suspended integrated transducer structure.

4D is a partial plan view of the suspended integrated transducer structure of FIG. 4C.

5A is a side sectional view showing an intermediate in a process of manufacturing the semiconductor transistor shown in FIG.

5B is a side sectional view showing an intermediate in a process of manufacturing the semiconductor transistor shown in FIG.

FIG. 5C is a side sectional view showing an intermediate in the process of manufacturing the semiconductor transistor shown in FIG. 3.

FIG. 5D is a side sectional view showing an intermediate in the process of manufacturing the semiconductor transistor shown in FIG. 3.

FIG. 6 is a block diagram of an electronic device for measuring the resistivity versus temperature characteristics of a YBCO layer in a bolometer according to the present invention.

FIG. 7: YBC in an example of a bolometer according to the present invention
It is a graph which shows the resistivity-temperature characteristic of O layer.

FIG. 8: YB incorporated in a pyroelectric detector according to the present invention
It is a block diagram of the electronic device for measuring the capacitance-versus-temperature characteristic of a CO layer.

FIG. 9: YBCO in an example of a pyroelectric detector according to the present invention
3 is a graph showing capacitance vs. temperature characteristics of layers.

[Explanation of symbols]

33 n-type semiconductor substrate 35 source electrode 35a p-type source connection region 36 YBCO layer (gate insulating YBCO layer, ferroelectric YBCO layer) 37 gate electrode 38 transistor channel 39 drain electrode 39a p-type drain connection region

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 21/8247 H01L 37/02 5F140 27/105 29/78 301G 27/14 27/10 444A 29/788 29 / 78 371 29/792 27/14 K 37/00 37/02 (72) Inventor Donald P. Butler United States, Texas, 75225, Dallas Bose, 6425, Electrical Engineering Department, Southern Methodist University (72) Inventor Zinep Serrick-Butler United States, Texas, 75225, Dallas Bose, 6425, Electrical Engineering Department, Southern Southern Methodist University (72), Inventor Shan・ Pao Chun A United States, Texas, 75225, Dallas, Bose, 6425, Electrical, Engineering, Department, Southern, Methodist, University, F Term (reference) 2G065 AA04 AB02 BA08 BA12 BA13 2G066 BA01 BA09 4M118 AA01 AB01 BA03 CA16 CA40 CB14 EA04 GA10 5F083 FR05 GA29 JA12 PR21 PR22 5F101 BA62 BD02 BH02 5F140 AC01 AC32 BA01 BD13 BF01 BF05 BJ01 BJ05 BJ23 CB01 CF01

Claims (4)

[Claims] 1. A gate-insulated transistor having the following structure: a first-conductivity-type semiconductor substrate having a substrate lower surface and a substrate upper surface; a second-conductivity-type source formed below a first region of the substrate upper surface. Connection region; second on the upper surface of the substrate
A drain connection region of the second conductivity type formed under a region; a source electrode having a lower surface of a source electrode connected to the first region; a drain electrode having a lower surface of a drain electrode connected to the second region; a crystal A ferroelectric gate insulating layer made of a crystalline or polycrystalline oxide semiconductor, wherein the oxide is (1) one or more elements selected from barium, strontium, and calcium, (2)
Formed of one or more elements selected from yttrium, lanthanum, and rare earth elements, (3) copper, and (4) oxygen, and the gate insulating layer has a gate insulating layer lower surface and a gate insulating layer upper surface, The resistivity of the gate insulating layer is greater than 0.1 Ωcm at 20 ° C., the lower surface of the gate insulator is on the third region of the upper surface of the first layer, and the third region is the first region and the third region. A portion of the first layer located between the two regions and directly below the third region, a gate insulating layer forming a conduction channel of the transistor; a gate electrode having a gate electrode lower surface and a gate electrode upper surface. The lower surface of the gate electrode is connected to the upper surface of the gate insulating layer. 2. The transistor according to claim 1, wherein the gate insulating layer has a resistivity of 1.4 at 20 ° C.
Is about 15 Ωcm, and the dielectric constant of the gate insulating layer is 20.
A transistor characterized by being greater than 50 at ° C. 3. The transistor according to claim 1, wherein the gate insulating layer is (1) one or more elements selected from yttrium, lanthanum, and rare earth elements, (2) barium, strontium, and calcium. One or more elements selected from, (3) copper,
And (4) is a crystalline semiconductor phase formed substantially from four elements of oxygen, and the stoichiometric composition ratio of yttrium, lanthanum, and a rare earth element to barium, strontium, and calcium, and copper is , Substantially 1:
A transistor characterized by being 2: 3. 4. The gate insulating transistor according to claim 1, wherein the ferroelectric gate insulating layer is formed in a first direction when (a) a first voltage larger than a first value is applied to the gate electrode. Polarized, and after the first voltage is applied to the gate electrode, allows carriers to pass through the conduction channel in the presence of an electromotive force along the conduction channel; (b) the first When a second voltage having a polarity opposite to that of the first voltage and larger than a second value is applied to the gate electrode, the ferroelectric gate insulating layer is polarized in a second direction opposite to the first direction. A carrier is unable to pass through the conduction channel when an electromotive force is present along the conduction channel after the first voltage is applied to the gate electrode.