RU2484483C1 - Manufacturing method of nano-electromechanical converter, and nano-electromechanical converter with autoelectronic emission - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: first, the appropriate planar integral circuit is created; for that purpose, contact platforms are formed on reverse side of the base; then, the first conducting layer is created; after that, circuit of a sensitive element of the converter is formed and a sacrificial layer is removed, and the method is completed with formation of the converter housing and formation of whiskers. Besides, at formation of the converter housing in a closed volume of the housing, gas medium with specified parameters is created, and formation of a whisker is performed due to supply of pulses of the specified shape to electrodes. As specified parameters of the medium, for example, pressure and/or dew point are used. Pulses in the form of half-period of sine wave of the specified amplitude and frequency are supplied to electrodes.

EFFECT: unification of different types of sensors with autoelectronic emission and reduction of standard sizes of different sensors.

4 cl, 12 dwg

Description

The invention relates to the field of measurement technology, in particular to means for measuring linear accelerations, angular velocities and low-intensity thermal fields in the infrared and terahertz regions.

Micromechanical gyroscope accelerometers — linear acceleration and angular velocity meters (see, for example, US Pat. No. 5,392,650 of February 28, 1995) use capacitive transducers of mechanical inertial mass displacement due to inertia forces or Coriolis forces to voltage.

Currently, capacitive converters are the most high-precision and have a large dynamic range of measurement. In micromechanical accelerometers and gyroscopes, working capacitances are several picofarads with inertial mass sizes in the region of 300 × 300 μm, and the sensitivity of a capacitive transducer is determined by its output parasitic capacitors, a preliminary amplifier of service elements.

In converters with nano-sizes, the working capacity will be significantly lower and amounts to (0.1 ÷ 1) femtofarads and, accordingly, the use of capacitive converters is almost impossible.

Thermal field meters are known in an uncooled infrared detector (see Uncooled Infrared Detectors Achieve New Performance Levels and Cost Targets Sofradis EC, Inc. Pesourece Center, 2009) based on microbolometric transducers.

The main type of uncooled detectors today are microbolometers. Infrared radiation in the wavelength range of 7–13 μm, reaching the surface of the material of the microbolometer detector, is absorbed and its surface heats up. As a result of this, the electrical resistance of the material changes, which is proportional to the temperature.

Currently, amorphous silicon (a-Si) and vanadium oxide (VOx) have been used in microbolometric detectors.

Amorphous silicon-based microbolometers are quite widespread due to the low manufacturing cost, but have worse noise characteristics compared to VOx-based detectors.

So known is a bolometric detector, a device for detecting infrared radiation using such a bolometric detector and a method for manufacturing this detector (RF Patent No. 2356017, IPC G01J 5/20, 10/14/2004).

The bolometric detector contains a sensitive part having one or more layers of sensitive material, the resistivity of which varies with temperature, the electrodes isolated from each other also act as infrared absorbers. Moreover, these electrodes are in contact with the sensitive material along at least one supporting region to position said sensitive part, acting as an electrical conductor relative to the readout circuit associated with the bolometric detector. The detector also contains at least one heat-insulating structure that electrically and mechanically connects each supporting region with the sensitive part. Areas of sensitive material that are not in contact with the electrodes have at least one corrugation oriented along a direction perpendicular to the plane containing the sensitive part of the bolometric detector.

The disadvantage of this technical solution is the low measurement accuracy and a narrow range of radiation registration.

Elimination of these disadvantages can be achieved by using as a transducer a measured quantity (angular velocity and linear acceleration) into electric voltage, field-effect converters (see, for example, RF patent No. 511114, 2003). In this case, an emission layer is applied to the earth electrode (cathode) during the manufacturing process, with a low electron output energy and being a source of electrons.

The deposition of carbon (diamond-like) films on the cathode surface allows one to reduce the electron work function, thus modifying the emitting surface and thereby reduces the magnitude of the applied voltage.

It should be noted that, despite the apparent attractiveness of using carbon films in the technology of manufacturing nanoelectromechanical sensors, their practical use is hindered by the high sensitivity of carbon films to any subsequent operations, as a result of which they lose all of their above properties.

This drawback is partially eliminated in the patent of the Russian Federation for a utility model (see patent No. 107593, IPC G01P 15/08, August 20, 2011), which presents a nanoelectromechanical accelerometer.

In this case, an emitting surface (whisker) is formed on the cathode in the form of a paraboloid of revolution. This allows you to increase the emission current without degradation of the emission properties.

The technical result from the use of the proposed inventions is to unify various types of sensors with field emission and reduce the size of various sensors, based on the fact that when measuring linear accelerations, angular velocities and thermal fields, a console placed in an electric field is used as a sensitive element, and the current value of linear acceleration, angular velocity, and temperature is judged by the change in the emission current depending on the mechanical deformation of the console when externally m disturbance.

The creation of an emission layer (whisker) after the formation of the sensitive element and its packaging in the housing allows the use of typical technological processes in the formation and packaging of the sensitive element.

For a method of manufacturing a nanoelectromechanical transducer based on surface micromechanical technology for a silicon or sapphire base, this technical result is achieved by first creating the corresponding planar integrated circuit, for which contact pads are formed on the back of the base, then the first conductive layer is created, and then the formation of the contour of the sensitive element of the transducer and remove the sacrificial layer, and complete the process sob by wrapping the transducer and forming whiskers.

In addition, when the converter is encased in a closed enclosure volume, a gaseous medium with specified parameters is created, and the whisker is formed by applying pulses of a given shape to the electrodes.

In addition, for example, the pressure and / or dew point are used as predetermined parameters of the medium.

In addition, pulses are applied to the electrodes in the form of a half-wave of a sine wave of a given amplitude and frequency.

For a nanoelectromechanical converter with field emission, containing a semiconductor structure with an electronic circuit and at least one sensing element made in the form of a console placed on the base of the converter with a gap relative to the conductive substrate, on the surface of which is facing the console, at least at least one whisker, the specified technical result is achieved by the fact that the whisker is formed at a distance from the free end of the console, less than or equal to Y1, determined according to the formula

Y ₁ ≤L - L cos (α) + (Z ₁ + d ₀ ) ctg (α)

where d ₀ is the distance from the cathode to the bottom surface of the console, when touching the end of the console of the substrate;

Z1 is the thickness of the first conductor layer of the semiconductor structure;

L is the length of the console;

α is the angular movement of the console from the no-load position to the touch of the end of the substrate console;

In addition, the sensitive element is made in the form of a bimorph element located on the base of the transducer with a gap relative to the conductive pad, on the surface of which, facing the bimorph element, at least one whisker is formed.

In addition, the first layer of the bimorph element is made of vanadium oxide, the second is made of tungsten.

In addition, two or more bimorph elements are combined into a matrix structure on a common crystal, on which are located the contact pads of rows and columns of the corresponding bimorph elements and contact pads of the “earth”, and the electronic circuit contains the corresponding electronic keys and multiplexers for polling rows and columns general video output.

The invention is illustrated by drawings.

Figure 1 shows the design of the sensitive element of the nanoelectromechanical accelerometer (NMA) with field emission.

Figure 2 shows the design of a nanoelectromechanical gyroscope-accelerometer (NMGA) with field emission.

Figure 3 shows the design of the sensitive element of the nanothermoelectromechanical transducer (NTEMP) with field emission.

Figure 4 shows the functional diagram of the sensitive element of the nanoelectromechanical sensor.

Figure 5 shows an enlarged diagram of the manufacturing technology of nanoelectromechanical sensors (NMA and NMHA).

Figure 6 shows an enlarged diagram of the manufacturing technology of a nanoelectromechanical sensor (NTEMP).

Figure 7 shows the sensitive element of the nanoelectromechanical transducer (NMA and NMHA) with field emission in the absence of disturbance (acceleration).

On Fig shows a sensitive element of nanothermoelectromechanical converters (NMA and NMHA) with field emission under the action of the acceleration vector opposite to the vector Y.

Figure 9 shows the sensitive element of nanothermoelectromechanical converters (NMA and NMHA) with field emission under the action of the acceleration vector along the vector Y.

Figure 10 shows the sensitive element of the nanothermoelectromechanical transducer (NTEMP) with field emission in the absence of a disturbing effect (heat flux).

11 shows a sensitive element of a nanothermoelectromechanical converter (NTEMP) with field emission at T> T0.

12 shows a sensitive element of a nanothermoelectromechanical converter (NTEMP) with field emission at T <T0.

Figure 1 shows:

1 - sapphire substrate (base);

2 - cathode;

3 - console;

4 - console support;

5 - emission layer (whisker);

7, 9 - contact pads.

Figure 2 shows:

1 - sapphire substrate (base);

2 - cathode;

3 - console;

4 - console support;

5 - emission layer (whisker);

6 - excitation electrodes;

7, 8, 9, 10 - contact pads.

Figure 3 shows:

1 - sapphire substrate (base);

2 - cathode;

3 - console;

3.1 - VOx layer;

3.2 - Layer W

4 - console support;

5 - emission layer (whisker).

Figure 4 shows:

11 - load resistor;

12 - operational amplifier;

13 is a sensitive element of a nanoelectromechanical measuring transducer.

Figure 5 shows:

1 - sapphire substrate (base);

3 - console;

5 - emission layer (whisker);

14 - sacrificial layer;

15 - cover;

16 - case.

Figure 6 shows:

1 - sapphire substrate (base);

3 - console;

3.1 - VOx layer;

3.2 - Layer W

5 - emission layer (whisker);

14 - sacrificial layer;

15 - cover;

15.1 - light filter;

15.2 - quartz.

16 - case.

7 shows:

1 - sapphire substrate (base);

3 - console;

On Fig shows:

1 - sapphire substrate (base);

3 - console;

Figure 9 shows:

1 - sapphire substrate (base);

3 - console;

Figure 10 shows:

1 - sapphire substrate (base);

3 - console;

3.1 - VOx layer;

3.2 - Layer W

11 shows:

1 - sapphire substrate (base);

3 - console;

3.1 - VOx layer;

3.2 - Layer W

12 shows:

1 - sapphire substrate (base);

3 - console;

3.1 - VOx layer;

3.2 - Layer W

In the process of manufacturing a nanoelectromechanical transducer based on surface micromechanical technology for a silicon or sapphire base, a corresponding planar integrated circuit is first created, for which contact pads are formed on the back of the base, then the first conductive layer (Z1) is created, and then the contour of the sensitive element is formed transducer and remove the sacrificial layer, and complete the method by encasing the transducer and forming Isker. When the transducer is packed in a closed volume of the housing, a gaseous medium is created with the given parameters, and the formation of the whisker is carried out by applying pulses of a given shape to the electrodes. As the specified parameters of the medium, for example, pressure and / or dew point, as well as other technological parameters are used depending on the required metrological characteristics of the converter. Most often, pulses are applied to the electrodes in the form of a half-wave of a sinusoid of a given amplitude and frequency. However, other pulse shapes may also be used.

A nanoelectromechanical converter with field emission in general contains a semiconductor structure (1, 5, 14) with an electronic circuit (11, 12) and at least one sensing element made in the form of a console 3 located on the base of the 1 converter with a gap with respect to a conductive pad (cathode) 2, on the surface of which facing the console, at least one whisker 5 is formed. The whisker 5 is formed at a distance from the free end of the console less than or equal to Y1, determined by the formula

Y ₁ ≤L - L cos (α) + (Z ₁ + d ₀ ) ctg (α)

where d ₀ is the distance from the cathode 2 to the bottom surface of the console 3, when touching the end of the substrate console;

Z ₁ is the thickness of the first conductor layer of the semiconductor structure;

L is the length of the console 3;

α is the angular movement of the console from the no-load position until it touches the end of the console 3 of the substrate. The sensitive element can be made in the form of a bimorph element (3.1, 3.2) placed on the base of the transducer with a gap relative to the conductive pad 2, on the surface of which, facing the bimorph element, at least one whisker is formed 5. The first layer of the bimorph element 3.1 can be made from vanadium oxide, the second 3.2 - from tungsten. Two or more bimorph elements can be combined into a matrix structure (not shown) on a common crystal, on which the contact pads of rows and columns (not shown) of the corresponding bimorph elements and contact pads of the earth are placed, and the electronic circuit can contain the corresponding electronic keys and multiplexers (not shown) for polling rows and columns associated with a common video output.

The design of the sensitive element of the nanoelectromechanical accelerometer (NMA) with field emission is shown in figure 1. The sensitive element is formed on the sapphire substrate (base) 1 and has a cantilever structure 3 fixed to the support 4. The formation of the emission layer (whisker) 5 occurs on the surface of the cathode 2, after the crystal is packed into the housing. The electrical connection of the crystal with the housing is through the contact pads of the crystal 7, 9.

The design of the sensitive element of the nanoelectromechanical gyroscope-accelerometer (NMGA) with field emission is shown in figure 2. The sensitive element is formed on the sapphire substrate (base) 1 and has a cantilever structure 3 fixed to the support 4. The formation of the emission layer (whisker) 5 occurs on the surface of the cathode 2, after the crystal is packed into the housing. The excitation electrodes 6 are used to set the longitudinal vibrations of the console in the plane of the substrate. The electrical connection of the crystal with the body is carried out through the contact pads of the crystal 7, 8, 9, 10.

The design of the nanothermoelectromechanical converter (NTEMP) with field emission is shown in Fig.3. The sensitive element is formed on a sapphire substrate (base) 1 and has a cantilever structure 3 mounted on a support 4. The cantilever 3 has a bimorph structure consisting of two layers - vanadium oxide (VOx) 3.1 and tungsten W 3.2.

The scheme for switching on a nanoelectromechanical converter with field emission is shown in Fig. 4. The supply voltage U is supplied through the load resistor 11 to the sensing element 13. The operational amplifier is used to coordinate the input and output of the sensor.

Figure 5, 6 shows an enlarged diagram of the manufacturing technology of nanoelectromechanical sensors (NMA, NMGA, NTEMP). The scheme consists of four main operations: the formation of the first layer, the formation of the contours of the sensitive element, the removal of the sacrificial layer 14, the packaging of the crystal of the nanoelectromechanical sensor (NMA, NMHA or NTEMP) and initialization.

Figure 7 shows the sensitive element of intangible magnetic resonance, NMGA in the absence of external disturbance. When the acceleration vector appears, acting along the H axis, the deformation of the sensitive element occurs: Fig. 8 - acceleration acts opposite to the vector Y, Fig. 9 - acceleration acts in the direction of the vector.

Figure 10 shows the sensitive element NTEM in the absence of external disturbance. When the temperature difference T> T0 (Fig. 11) and T <T0 (Fig. 12) appears, the console material expands linearly. Since the cantilever of the NTEMP sensitive element has a bimorph structure consisting of vanadium oxide (VOx) and tungsten (W), the expansion coefficients of which are different, the cantilever deforms mechanically, leading to a change in the gap d0.

The essence of the work of nanoelectromechanical sensors is to change the emission current due to a change in the working gap d0. In this case, the emission current i will be proportional to the measured physical quantity

$$i_a=K_a\dot{W}$$

$$i_g=K_g\dot{\omega }$$

$$i_t=K_{t}T$$

where K _a = K _ma K _ea

K _g = K _mg K _eg

K _t = K _mt K _et

K _a , K _g , K _t - conversion coefficients (scale factors) of the accelerometer, gyroscope and thermionic converter;

- измеряемые величины: линейные ускорения, угловые скорости и температура; $$\dot{W},\dot{\omega },\text{T}$$

- measured values: linear accelerations, angular velocities and temperature;

K _ma , K _mg , K _mt — conversion factors of measured quantities (linear accelerations, angular velocities and temperature) into mechanical displacement;

To _ea , To _eg , To _et - the conversion coefficients of the mechanical movement of the console in the magnitude of the emission current.

As a result, we obtain a technical result from the use of the proposed inventions, which consists in unifying various types of sensors with field emission and reducing the sizes of various sensors, based on the fact that when measuring linear accelerations, angular velocities and thermal fields, a console located in electric field, and the current value of linear acceleration, angular velocity and temperature is judged by the change in the emission current depending on the mechanical def mation console with external perturbations.

Claims (4)

1. A method of manufacturing a nanoelectromechanical transducer based on surface micromechanical technology for a silicon or sapphire base, which consists in the fact that previously on a silicon or sapphire base create a layered semiconductor structure with contact pads, containing at least a layer of a sensitive element, an emission layer and a sacrificial layer between them, then the contour of the console of the sensor element of the transducer is formed from the layer material element by removing the middle sacrificial layer between the layer of the sensing element, the base and the emission layer formed on this basis, and complete the method by wrapping the transducer and forming whiskers on the emission layer. 2. The manufacturing method according to claim 1, characterized in that when the transducer is packed in a closed enclosure volume, a gaseous medium is created with predetermined parameters, and the whisker is formed by applying pulses of a given shape to the electrodes. 3. The manufacturing method according to claim 2, characterized in that, for example, the pressure and / or dew point is used as the specified medium parameters. 4. The manufacturing method according to claim 2, characterized in that the pulses are applied to the electrodes in the form of a half-wave of a sine wave of a given amplitude and frequency.

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