RU2528541C1 - Method of pressure resistive tensor transducer built around thin-film nano- and microelectromechanical system (mamos) - Google Patents

Abstract

FIELD: instrument making.

SUBSTANCE: proposed method consists in grinding of membrane surface, forming thereon of dielectric film and strain gages with low-resistance jumpers and contact sites there between and connecting output terminals to contact sites. After connecting of said output conductors to contact sites of MAMOS, voltage (or feed current) is switched on and kept up for time required for settlement of initial output signal to magnitude U₀₁=U₀₀±Δ(U₀₁), where U₀₀ is MAMOS initial output signal magnitude, Δ(U₀₁) is admissible fluctuation of initial output signal. Voltage (or feed current) is switched off. After keeping MAMOS in OFF state for time sufficient for rendering said system to state before switching on of voltage (or feed current), voltage (or feed current) is switched on to define time interval Δ(τ₀₂) from switching of voltage to initial output signal of test magnitude U₀₂=U₀₀±Δ(U₀₂), where Δ(U₀₂)=γ₀ U_H is admissible deviation of initial output signal U₀₂; γ₀ us transducer basic error; U_H - is nominal output signal of the transducer. In case time interval Δ(τ₀₂) from switching of voltage (or feed current) to initial output signal of test magnitude U₀₂ does not exceed tolerable magnitude taken as a time stability criterion and defined experimentally by statistical data for particular transducer, then this assembly is transferred to next operations.

EFFECT: higher time stability, longer life, lower error at transient temperatures and higher vibration accelerations.

2 dwg

Description

The present invention relates to measuring equipment, in particular to strain gauge pressure sensors based on thin-film nano- and microelectromechanical systems (NIMEMS) with a bridge measuring circuit, intended for use in control systems, monitoring and diagnostics of technically complex objects of long-term functioning under conditions of unsteady temperature and increased vibration acceleration.

A known method of manufacturing a strain gauge pressure sensor based on NiMEMS, intended for use in control systems, monitoring and diagnostics of technically complex objects with long-term functioning under the influence of unsteady temperatures and increased vibration accelerations, consists in polishing the surface of the membrane, applying a dielectric to it, forming a strain-sensitive circuit on it attaching a terminal block to an elastic element and attaching a terminal block to a contact area am tensosensitivity circuit, wherein prior to application of the dielectric is manufactured dielectric sleeve directly into the recess of the elastic member, polished surface of the membrane simultaneously with the polishing of the end face of the sleeve, and then applying a dielectric on the membrane of the elastic member and the bushing end and forming tenzoskhemu on a dielectric membrane and sleeve [1].

A disadvantage of the known manufacturing method is the relatively large temporary instability due to the different shapes of the circumferential and radial strain gauges included in the opposite arms of the bridge measuring circuit. This is due to the fact that the different shape of the strain gages leads to different temporary changes in the resistance of these strain gages, including due to the different rates of degradation and relaxation processes in the circumferential and radial strain gages.

A known method of manufacturing a strain gauge pressure sensor based on a thin-film NIMEMS, intended for use in control systems, monitoring and diagnostics of technically complex objects with long-term functioning under the influence of unsteady temperatures and high vibration accelerations, which consists in polishing the surface of the membrane, forming on it a dielectric film and strain elements with low resistance jumpers and pads between them using a strain gauge template a layer having a configuration of strain elements in zones compatible with low-resistance jumpers and contact pads, in the form of strips including images of strain elements and their continuation in two opposite directions, and in areas combined with contact pads, partially coinciding with the configuration of contact pads and remote from strip sites, connecting lead-out conductors to the contact pads in areas remote from the strip sites [2].

A disadvantage of the known manufacturing method is the relatively low temporary stability and a large error when exposed to unsteady temperatures and increased vibration accelerations due to the lack of detection of potentially unstable NiMEMS with an imperfect structure at the early stages of manufacturing. The absence of such detection during operation leads to different temporary changes in the resistance of the NiMEMS strain elements, including due to the different rates of degradation and relaxation processes in the strain elements included in different arms of the bridge measuring circuit. Insufficient temporal stability leads to an increase in temporal error and a decrease in the resource and service life of the sensor. In addition, the imperfection of the NiMEMS structure is the cause of the sensor error under the influence of unsteady temperatures and increased vibration accelerations due to the different reactions of the strain gauges included in different arms of the bridge measuring circuit to the above effects.

The aim of the invention is to increase the temporal stability, resource, service life, reduce the error under the influence of unsteady temperatures and increased vibration acceleration, as well as increase the manufacturability of forecasting by more accurately and quickly identifying potentially unstable NiMEMSs with an imperfect structure at the early stages of manufacturing.

This goal is achieved by the fact that in the method of manufacturing a strain gauge pressure sensor based on a thin-film NiMEMS, which consists in polishing the surface of the membrane, forming a dielectric film and strain elements on it with low resistance jumpers and contact pads between them using a strain gauge layer template having the configuration of strain elements in the zones combined with low-resistance jumpers and contact pads, in the form of strips, including images of strain elements and their continuation in two opposite directions, and in areas compatible with the contact pads, which partially coincides with the configuration of the contact pads and sections remote from the strips, connecting the lead conductors to the contact pads in areas remote from the strip strips in accordance with the claimed invention, after connecting the lead conductors to The contact pads of NiMEMS strain elements include the voltage (or supply current) of NiMEMS and can withstand for the time necessary to establish the initial output signal to values

$$U_{01}=U_{00}\pm \Delta (U_{01}),$$

where U ₀₀ is the value of the initial output signal NIMEMS;

- допустимая флуктуация начального выходного сигнала; $$\Delta (U_{01})$$

- permissible fluctuation of the initial output signal;

they turn off the voltage (or supply current) and after holding NiMEMS in the off state for a time sufficient to return NiMEMS to the state preceding the voltage (or supply current) was turned on, turn on the voltage (or supply current) and determine the time interval Δ (τ ₀₂ ) from the moment the voltage (or supply current) is turned on until the initial output signal of the test value is reached

$$U_{02}=U_{00}\pm \Delta (U_{02}),$$

- допустимое отклонение значения начального выходного сигнала U₀₂; $$\Delta (U_{02})={\gamma }_0{\text{U}}_{\text{H}}$$

- permissible deviation of the value of the initial output signal U ₀₂ ;

γ ₀ is the basic error of the sensor;

U _H is the nominal output signal of the sensor, and if the time interval Δ (τ ₀₂ ) from the moment the voltage (or supply current) is turned on until the initial output signal reaches the test value, U ₀₂ does not exceed the maximum permissible value, which is taken as a criterion of temporary stability and is determined experimentally according to statistics for a specific sensor size, this assembly is passed on to subsequent operations.

The inventive method is implemented as follows.

A membrane with a peripheral base in the form of a shell of revolution is made (for example, from 36NKVKhBTY alloy) using blade cutting methods using in the last stages of electric discharge machining. The surface of the membrane is polished using electrochemical-mechanical finishing and polishing or diamond finishing and polishing. Using thin-film methods, a dielectric film in the form of a SiO - SiO ₂ structure with a chromium sublayer and a strain-sensitive film (for example, from X20H75Y alloy) are successively applied in continuous layers on a planar surface of the membrane. When forming jumpers and contact pads by photolithography, a low film (for example, Zl gold 999.9 m), with a sublayer (vanadium) is applied in a continuous layer to a strain-sensitive film (from X20H75Y alloy). Jumpers and pads are formed by photolithography using a jumper template and pads. The formation of jumpers and pads can be carried out mask method. In this case, the low-resistance film is not applied in a continuous layer, but is sprayed through a mask. The formation of strain elements is carried out by the method of photolithography using ion-chemical etching in an argon medium and a template of a strain-sensitive layer having the configuration of the strain elements in zones combined with low-resistance jumpers and contact pads, in the form of strips including images of the strain elements and their continuation in two opposite directions, and in areas combined with contact pads - partially coinciding with the configuration of contact pads and sections remote from the strips. After connecting the output conductors to the NiMEMS pads, they include the voltage (or supply current) of the NiMEMS and stand for the time necessary to establish the initial output signal to the value

$$U_{01}=U_{00}\pm \Delta (U_{01}),$$

where U ₀₀ is the value of the initial output signal NIMEMS;

- допустимая флуктуация начального выходного сигнала. $$\Delta (U_{01})$$

- permissible fluctuation of the initial output signal.

This operation is necessary to accurately determine the value of the initial output signal of NiMEMS; therefore, it is advisable to limit the allowable fluctuation to a value of (0.001 ... 0.01)% of the nominal output signal of NiMEMS. They turn off the voltage (or supply current) and maintain NiMEMS in the off state for a time sufficient to return NiMEMS to the state preceding the inclusion of voltage (or supply current). Turn on the voltage (or supply current) and determine the time interval Δ (τ ₀₂ ) from the moment the voltage (or supply current) is turned on until the initial output signal of the test value is reached

$$U_{02}=U_{00}\pm \Delta (U_{02}),$$

- допустимое отклонение значения начального выходного сигнала U₀₂; $$\Delta (U_{02})={\gamma }_0{\text{U}}_{\text{H}}$$

- permissible deviation of the value of the initial output signal U ₀₂ ;

γ ₀ is the basic error of the sensor;

U _H - nominal output signal of the sensor.

позволяет увеличить быстродействие прогнозирования без ухудшения точности и качества, так как разница $$U_{02}-\Delta (U_{02})$$

находится в пределах погрешности, а быстродействие увеличивается на 20…30%. При идентичности структур тонкопленочных тензорезисторов, размеров и характеристик их элементов и переходов, включенных в различные плечи мостовой цепи НиМЭМС, обеспечивается минимум интервала времени Δ(τ₀₂). Если интервал времени Δ(τ₀₂) от момента включения напряжения (или тока питания) до достижения начального выходного сигнала тестового значения U₀₂ не превышает предельно допустимого значения, которое принимается за критерий временной стабильности и определяется экспериментальным путем по статистическим данным для конкретного типоразмера датчика, то данную сборку передают на последующие операции. Если интервал времени Δ(τ₀₂) от момента включения напряжения (или тока питания) до достижения начального выходного сигнала тестового значения U₀₂ превышает предельно допустимое значение, то данную сборку списывают в технологический отход или реставрируют.Using a text value $$U_{02}$$

allows you to increase the speed of forecasting without compromising accuracy and quality, since the difference $$U_{02}-\Delta (U_{02})$$

It is within the margin of error, and speed increases by 20 ... 30%. With the identity of the structures of thin-film strain gauges, the sizes and characteristics of their elements and transitions included in different shoulders of the NiMEMS bridge circuit, a minimum of the time interval Δ (τ ₀₂ ) is provided. If the time interval Δ (τ ₀₂ ) from the moment the voltage (or power supply current) is turned on until the initial output signal reaches the test value U ₀₂ does not exceed the maximum permissible value, which is taken as a criterion of temporary stability and is determined experimentally from statistics for a specific sensor size, then this assembly is passed on to subsequent operations. If the time interval Δ (τ ₀₂ ) from the moment the voltage (or supply current) is turned on until the initial output signal reaches the test value U ₀₂ exceeds the maximum permissible value, then this assembly is written off as a process waste or restored.

To establish a causal relationship of the claimed features and the achieved technical effect, we consider the most common elements of thin-film strain gauges used in the creation of NiMEMS. We note the most common elements that affect the temporal stability of thin-film strain gauges used to create NiMEMS with identical strain gauges used in the manufacture of pressure sensors for long-term operation under conditions of unsteady temperatures and increased vibration accelerations. An analysis of the known solutions showed that the following thin-film elements shown in Fig. 1 can be attributed to such elements: dielectric 7, strain resistance 2, adhesive 3, contact 4. Thin-film conductive elements must also be referred to elements of thin-film strain gauges that affect stability. In Fig. 1, the relations between the thicknesses of thin-film elements and etching wedges are not conventionally shown.

The conductive elements of the strain gages are connected in series with the contact elements and are used to connect the strain gages to the bridge measuring circuit and to the power supply and signal conversion circuit. From the point of view of increasing stability, we will consider only conductive elements located in areas from contact elements to nodes of a bridge measuring circuit. As a rule, these nodes coincide with the connection points of the output conductors connecting the bridge circuit to the power supply and signal conversion circuit. When performing NiMEMS in the form of a bridge measuring circuit with four working strain gages, as shown in figure 2, in a stationary temperature mode, you can record the output signal NiMEMS in the form

$$U=E(R_2{R}_{\mathrm{four}}-R_{\mathrm{one}}{R}_3){[(R_{\mathrm{one}}+R_2)(R_3+R_{\mathrm{four}})]}^{-\mathrm{one}},\text{(one)}$$

where E is the supply voltage of the bridge measuring circuit;

R ₁ , R ₂ , R ₃ , R ₄ - resistance of the strain gages R1, R2, R3, R4.

We define the condition of temporary stability of NiMEMS in the form

$$U(\tau +\Delta \tau )=U(\tau ),\text{(2)}$$

- начальный выходной сигнал в момент времени $$(\tau +\Delta \tau )$$

;Where $$U(\tau +\Delta \tau )$$

- initial output signal at time $$(\tau +\Delta \tau )$$

;

- начальный выходной сигнал в момент времени τ; $$U(\tau )$$

- the initial output signal at time τ;

- любой интервал времени в пределах срока службы датчика. $$\Delta \tau$$

- any time interval within the life of the sensor.

получим условие стабильности НиМЭМС в развернутом видеAfter substituting expression (1) into expression (2) and ensuring the necessary temporary stability of the power source $$E(\tau +\Delta \tau )=E(\tau ),$$

we obtain the condition of stability of NIMEMS in expanded form

$$\begin{array}{l}[R_2(\tau +\Delta \tau )R_{\mathrm{four}}(\tau +\Delta \tau )-R_{\mathrm{one}}(\tau +\Delta \tau )R_{\mathrm{one}}(\tau +\Delta \tau )]\times {\{}^{[}=\\ =[R_2(\tau )R_{\mathrm{four}}(\tau )-R_{\mathrm{one}}(\tau )R_3(\tau )]\times {\{}^{[}\text{(3)}\end{array}$$

An analysis of the obtained condition (3) shows that it can be provided with countless combinations of resistance of strain gauges and their functional time dependences. At the same time, any combinations in the case of inequality of the resistances of different strain gages of the NiMEMS bridge circuit will require, in order to fulfill the stability conditions, various, interconnected and accurate functional time dependences of the resistance of the strain gages. Similarly, any combinations in case of differences in the functional dependences of the strain gages on time will require, for the stability conditions to be met, the various and interconnected resistances of the strain gages to be dependent on their functional time dependences. Given that such functional dependences are very difficult to implement, from the point of view of practical feasibility, the particular stability conditions in the form of equality of the resistance of the strain gauges at the initial time and the same functional dependence of these resistance on time are optimal, i.e.

$$R_{\mathrm{one}}(\tau )=R_2(\tau )=R_3(\tau )=R_{\mathrm{four}}(\tau )=R(\tau ),\text{(four)}$$

$$R_{\mathrm{one}}(\tau +\Delta \tau )=R_2(\tau +\Delta \tau )=R_3(\tau +\Delta \tau )=R_{\mathrm{four}}(\tau +\Delta \tau )=R(\tau +\Delta \tau ),\text{(5)}$$

- сопротивления тензорезисторов в различные моменты времени вне зависимости от номера тензорезистора в мостовой схеме. Тогда можно записать соотношения (6), (7) в сокращенном видеWhere $$R(\tau ),R(\tau +\Delta \tau )$$

- resistance of strain gages at various points in time, regardless of the number of the strain gauge in the bridge circuit. Then we can write relations (6), (7) in abbreviated form

$$R_j(\tau )=R(\tau ),R_j(\tau +\Delta \tau )=R(\tau +\Delta \tau )\text{(6)}$$

и $$(\tau +\Delta \tau )$$

соответственноIn the case of the execution of strain gauges in the form of a number N of uniformly distributed identical strain gauges connected by low-resistance jumpers as a result of the analysis of the relationship of thin-film elements of the strain gauge (Fig. 1), it is possible to determine the resistance of the jth thin-film strain gauge at a time $$\tau$$

and $$(\tau +\Delta \tau )$$

respectively

$$R_j(\tau +\Delta \tau )={\displaystyle \sum _{i=1}^N{R}_{Pij}(\tau +\Delta \tau )+2R_{PAij}(\tau +\Delta \tau )+2R_{Аij}(\tau +\Delta \tau )+2R_{АКij}(\tau +\Delta \tau )+2R_{Кij}(\tau +\Delta \tau )+2R_{КПj}(\tau +\Delta \tau )+2R_{Пj}(\tau +\Delta \tau )},\text{ (8)}$$

где $$R_{Pij},R_{Аij},R_{Кij},R_{Пj}$$

- соответственно сопротивление тензорезистивного, адгезионного, контактного элемента i-го тензоэлемента j-го тензорезистора; $$R_j(\tau )={\displaystyle \sum _{i=\mathrm{one}}^N{R}_{Pij}(\tau )+2R_{PAij}(\tau )+2R_{\mathrm{BUT}ij}(\tau )+2R_{\mathrm{BUT}\mathrm{TO}ij}(\tau )+2R_{\mathrm{TO}ij}(\tau )+2R_{\mathrm{TO}Pj}(\tau )+2R_{Pj}(\tau )},\text{(7)}$$

$$R_j(\tau +\Delta \tau )={\displaystyle \sum _{i=\mathrm{one}}^N{R}_{Pij}(\tau +\Delta \tau )+2R_{PAij}(\tau +\Delta \tau )+2R_{\mathrm{BUT}ij}(\tau +\Delta \tau )+2R_{\mathrm{BUT}\mathrm{TO}ij}(\tau +\Delta \tau )+2R_{\mathrm{TO}ij}(\tau +\Delta \tau )+2R_{\mathrm{TO}Pj}(\tau +\Delta \tau )+2R_{Pj}(\tau +\Delta \tau )},\text{(8)}$$

Where $$R_{Pij},R_{\mathrm{BUT}ij},R_{\mathrm{TO}ij},R_{Pj}$$

- respectively, the resistance of the strain gauge, adhesive, contact element of the i-th strain element of the j-th strain gauge;

- соответственно сопротивление переходов элементов тензорезистивный - адгезионный, адгезионный - контактный, контактный - проводящий i-го тензоэлемента j-го тензорезистора; $$R_{P\mathrm{BUT}ij},R_{F\mathrm{TO}ij},R_{\mathrm{TO}Pj}$$

- respectively, the resistance of the transitions of the elements of the strain gauge - adhesive, adhesive - contact, contact - conductive i-th strain element of the j-th strain gauge;

7 = 1, 2, 3, 4 - the number of the strain gauge in the bridge circuit;

i = 1 ... N is the number of the strain gauge in the strain gauge.

In the most general case, the resistance of each element of a thin-film strain gauge is determined by the specific surface resistance, length and width of the element or transition. Theoretical and experimental studies of the long-term influence of external factors on NiMEMS (ideally in the absence of defects) have shown that, to the greatest extent, the parameters determining the resistance of strain gages are affected by deformations, temperatures and time. In accordance with expressions (7), (8), we present mathematical models of resistances of thin-film strain gauges in the form of the following expressions:

$$\begin{array}{l}{R}_j(\tau )={\displaystyle \sum _{i=\mathrm{one}}^N{\rho }_{PiJ}({\epsilon }_{PiJ},T_{PiJ},\tau )l_{PiJ}({\epsilon }_{PiJ},T_{PiJ},\tau ){[({\epsilon }_{PiJ},T_{PiJ},\tau )]}^{-\mathrm{one}}+2}{\rho }_{P\mathrm{BUT}iJ}({\epsilon }_{P\mathrm{BUT}iJ},T_{P\mathrm{BUT}iJ},\tau )l_{P\mathrm{BUT}iJ}({\epsilon }_{P\mathrm{BUT}iJ},T_{P\mathrm{BUT}iJ},\tau )\times \\ {[}^{(}+2{\rho }_{\mathrm{BUT}iJ}({\epsilon }_{\mathrm{BUT}iJ},T_{\mathrm{BUT}iJ},\tau )l_{\mathrm{BUT}iJ}({\epsilon }_{\mathrm{BUT}iJ},T_{\mathrm{BUT}iJ},\tau )\times {[}^{(}+\\ 2{\rho }_{\mathrm{BUT}\mathrm{TO}iJ}({\epsilon }_{\mathrm{BUT}\mathrm{TO}iJ},T_{\mathrm{BUT}\mathrm{TO}iJ},\tau )l_{\mathrm{BUT}\mathrm{TO}iJ}({\epsilon }_{\mathrm{BUT}\mathrm{TO}iJ},T_{\mathrm{BUT}\mathrm{TO}iJ},\tau )\times {[}^{(}+2{\rho }_{\mathrm{TO}iJ}({\epsilon }_{\mathrm{TO}iJ},T_{\mathrm{TO}iJ},\tau )l_{\mathrm{TO}iJ}({\epsilon }_{\mathrm{TO}iJ},T_{\mathrm{TO}iJ},\tau )\times {[}^{(}+\\ 2{\rho }_{\mathrm{TO}PJ}({\epsilon }_{\mathrm{TO}PJ},T_{\mathrm{TO}PJ},\tau )l_{\mathrm{TO}PJ}({\epsilon }_{\mathrm{TO}PJ},T_{\mathrm{TO}PJ},\tau )\times {[}^{(}+2{\rho }_{PJ}({\epsilon }_{PJ},T_{PJ},\tau )l_{PJ}({\epsilon }_{PJ},T_{PJ},\tau )\times {[}^{(}\text{(9)}\end{array}$$

$$\begin{array}{l}{R}_j(\tau )={\displaystyle \sum _{i=\mathrm{one}}^N\begin{array}{l}{\rho }_{PiJ}({\epsilon }_{PiJ},T_{PiJ},\tau +\Delta \tau )l_{PiJ}({\epsilon }_{PiJ},T_{PiJ},\tau +\Delta \tau ){[}^{(}+\\ 2\end{array}}\\ {\rho }_{P\mathrm{BUT}iJ}({\epsilon }_{P\mathrm{BUT}iJ},T_{P\mathrm{BUT}iJ},\tau +\Delta \tau )l_{P\mathrm{BUT}iJ}({\epsilon }_{P\mathrm{BUT}iJ},T_{P\mathrm{BUT}iJ},\tau +\Delta \tau )\times \\ {[}^{(}+2{\rho }_{\mathrm{BUT}iJ}({\epsilon }_{\mathrm{BUT}iJ},T_{\mathrm{BUT}iJ},\tau +\Delta \tau )l_{\mathrm{BUT}iJ}({\epsilon }_{\mathrm{BUT}iJ},T_{\mathrm{BUT}iJ},\tau +\Delta \tau )\times {[}^{(}+\\ 2{\rho }_{\mathrm{BUT}\mathrm{TO}iJ}({\epsilon }_{\mathrm{BUT}\mathrm{TO}iJ},T_{\mathrm{BUT}\mathrm{TO}iJ},\tau +\Delta \tau )l_{\mathrm{BUT}\mathrm{TO}iJ}({\epsilon }_{\mathrm{BUT}\mathrm{TO}iJ},T_{\mathrm{BUT}\mathrm{TO}iJ},\tau +\Delta \tau )\times {[}^{(}\\ +2{\rho }_{\mathrm{TO}iJ}({\epsilon }_{\mathrm{TO}iJ},T_{\mathrm{TO}iJ},\tau +\Delta \tau )l_{\mathrm{TO}iJ}({\epsilon }_{\mathrm{TO}iJ},T_{\mathrm{TO}iJ},\tau +\Delta \tau )\times {[}^{(}+\\ 2{\rho }_{\mathrm{TO}PJ}({\epsilon }_{\mathrm{TO}PJ},T_{\mathrm{TO}PJ},\tau +\Delta \tau )l_{\mathrm{TO}PJ}({\epsilon }_{\mathrm{TO}PJ},T_{\mathrm{TO}PJ},\tau +\Delta \tau )\times {[}^{(}+\\ 2{\rho }_{PJ}({\epsilon }_{PJ},T_{PJ},\tau +\Delta \tau )l_{PJ}({\epsilon }_{PJ},T_{PJ},\tau +\Delta \tau )\times {[}^{(}\text{(10)}\end{array}$$

- Удельное поверхностное сопротивление соответствующих элементов и переходов i-го тензоэлемента j-го тензорезистора;Where $${\rho }_{RiJ},{\rho }_{R\mathrm{BUT}iJ},{\rho }_{\mathrm{BUT}iJ},{\rho }_{\mathrm{BUT}\mathrm{TO}iJ},{\rho }_{\mathrm{TO}iJ},{\rho }_{PJ},{\rho }_{\mathrm{TO}PJ},$$

- The specific surface resistance of the corresponding elements and transitions of the i-th strain element of the j-th strain gauge;

- относительная деформация, воздействующая на соответствующие элементы и переходы i-го тензоэлемента j-го тензорезистора; $${\epsilon }_{RiJ},{\epsilon }_{R\mathrm{BUT}iJ},{\epsilon }_{\mathrm{BUT}iJ},{\epsilon }_{\mathrm{BUT}\mathrm{TO}iJ},{\epsilon }_{\mathrm{TO}iJ},{\epsilon }_{PJ},{\epsilon }_{\mathrm{TO}PJ},$$

- relative deformation acting on the corresponding elements and transitions of the i-th strain element of the j-th strain gauge;

- температура, воздействующая на соответствующие элементы и переходы i-го тензоэлемента j-го тензорезистора. $$T_{RiJ},T_{R\mathrm{BUT}iJ},T_{\mathrm{BUT}iJ},T_{\mathrm{BUT}\mathrm{TO}iJ},T_{\mathrm{TO}iJ},T_{PJ},T_{\mathrm{TO}PJ},$$

is the temperature acting on the corresponding elements and transitions of the i-th strain element of the j-th strain gauge.

Then the extended particular conditions for the stability of NiMEMS can be represented as

$$\begin{array}{l}{R}_j(\tau )={\displaystyle \sum _{i=\mathrm{one}}^N{\rho }_{PiJ}({\epsilon }_{PiJ},T_{PiJ},\tau )l_{PiJ}({\epsilon }_{PiJ},T_{PiJ},\tau ){[({\epsilon }_{PiJ},T_{PiJ},\tau )]}^{-\mathrm{one}}+2}{\rho }_{P\mathrm{BUT}iJ}({\epsilon }_{P\mathrm{BUT}iJ},T_{P\mathrm{BUT}iJ},\tau )l_{P\mathrm{BUT}iJ}({\epsilon }_{P\mathrm{BUT}iJ},T_{P\mathrm{BUT}iJ},\tau )\times \\ {[}^{(}+2{\rho }_{\mathrm{BUT}iJ}({\epsilon }_{\mathrm{BUT}iJ},T_{\mathrm{BUT}iJ},\tau )l_{\mathrm{BUT}iJ}({\epsilon }_{\mathrm{BUT}iJ},T_{\mathrm{BUT}iJ},\tau )\times {[}^{(}+\\ 2{\rho }_{\mathrm{BUT}\mathrm{TO}iJ}({\epsilon }_{\mathrm{BUT}\mathrm{TO}iJ},T_{\mathrm{BUT}\mathrm{TO}iJ},\tau )l_{\mathrm{BUT}\mathrm{TO}iJ}({\epsilon }_{\mathrm{BUT}\mathrm{TO}iJ},T_{\mathrm{BUT}\mathrm{TO}iJ},\tau )\times {[}^{(}+2{\rho }_{\mathrm{TO}iJ}({\epsilon }_{\mathrm{TO}iJ},T_{\mathrm{TO}iJ},\tau )l_{\mathrm{TO}iJ}({\epsilon }_{\mathrm{TO}iJ},T_{\mathrm{TO}iJ},\tau )\times {[}^{(}+\\ 2{\rho }_{\mathrm{TO}PJ}({\epsilon }_{\mathrm{TO}PJ},T_{\mathrm{TO}PJ},\tau )l_{\mathrm{TO}PJ}({\epsilon }_{\mathrm{TO}PJ},T_{\mathrm{TO}PJ},\tau )\times {[}^{(}+2{\rho }_{PJ}({\epsilon }_{PJ},T_{PJ},\tau )l_{PJ}({\epsilon }_{PJ},T_{PJ},\tau )\times {[}^{(}=\text{R (}\tau \text{) (eleven)}\end{array}$$

$$\begin{array}{l}{R}_j(\tau )={\displaystyle \sum _{i=\mathrm{one}}^N\begin{array}{l}{\rho }_{PiJ}({\epsilon }_{PiJ},T_{PiJ},\tau +\Delta \tau )l_{PiJ}({\epsilon }_{PiJ},T_{PiJ},\tau +\Delta \tau ){[}^{(}+\\ 2\end{array}}\\ {\rho }_{P\mathrm{BUT}iJ}({\epsilon }_{P\mathrm{BUT}iJ},T_{P\mathrm{BUT}iJ},\tau +\Delta \tau )l_{P\mathrm{BUT}iJ}({\epsilon }_{P\mathrm{BUT}iJ},T_{P\mathrm{BUT}iJ},\tau +\Delta \tau )\times \\ {[}^{(}+2{\rho }_{\mathrm{BUT}iJ}({\epsilon }_{\mathrm{BUT}iJ},T_{\mathrm{BUT}iJ},\tau +\Delta \tau )l_{\mathrm{BUT}iJ}({\epsilon }_{\mathrm{BUT}iJ},T_{\mathrm{BUT}iJ},\tau +\Delta \tau )\times {[}^{(}+\\ 2{\rho }_{\mathrm{BUT}\mathrm{TO}iJ}({\epsilon }_{\mathrm{BUT}\mathrm{TO}iJ},T_{\mathrm{BUT}\mathrm{TO}iJ},\tau +\Delta \tau )l_{\mathrm{BUT}\mathrm{TO}iJ}({\epsilon }_{\mathrm{BUT}\mathrm{TO}iJ},T_{\mathrm{BUT}\mathrm{TO}iJ},\tau +\Delta \tau )\times {[}^{(}\\ +2{\rho }_{\mathrm{TO}iJ}({\epsilon }_{\mathrm{TO}iJ},T_{\mathrm{TO}iJ},\tau +\Delta \tau )l_{\mathrm{TO}iJ}({\epsilon }_{\mathrm{TO}iJ},T_{\mathrm{TO}iJ},\tau +\Delta \tau )\times {[}^{(}+\\ 2{\rho }_{\mathrm{TO}PJ}({\epsilon }_{\mathrm{TO}PJ},T_{\mathrm{TO}PJ},\tau +\Delta \tau )l_{\mathrm{TO}PJ}({\epsilon }_{\mathrm{TO}PJ},T_{\mathrm{TO}PJ},\tau +\Delta \tau )\times {[}^{(}+\\ 2{\rho }_{PJ}({\epsilon }_{PJ},T_{PJ},\tau +\Delta \tau )l_{PJ}({\epsilon }_{PJ},T_{PJ},\tau +\Delta \tau )\times {[}^{(}=R(\tau +\Delta \tau )\text{(12)}\end{array}$$

The obtained extended particular stability conditions (11) and (12) can be satisfied for countless combinations of resistances of strain gauge elements and their functional dependences on deformations, temperature, and time. By analogy with the previous arguments, any combinations in the case of inequality of the resistances of the elements of the strain gauges of the NiMEMS bridge circuit and the identity of their functional dependences on the influencing factors will require different, interconnected and accurate functional dependencies of the resistance of the strain gauges to fulfill the extended particular stability conditions. Given that such functional dependencies are very difficult to implement, we can write the particular conditions for stability of NiMEMS in the form

$$\begin{array}{l}{\rho }_{Pij}={\rho }_P,{\epsilon }_{Pij}={\epsilon }_P,T_{Pij}=T_P,l_{Pij}=l_P,b_{Pij}=b_P,{\rho }_{PAij}={\rho }_{PA},{\epsilon }_{PAij}={\epsilon }_{PA},T_{PAij}=T_{PA},l_{PAij}=l_{PA},b_{PAij}\\ =b_{PA},{\rho }_{Aij}={\rho }_A,{\epsilon }_{Aij}={\epsilon }_A,T_{Aij}=T_A,l_{Aij}=l_A,b_{Aij}=b_A,{\rho }_{Aij}={\rho }_A,{\epsilon }_{AKij}={\epsilon }_{AK},T_{AKij}=T_{AK},l_{AKij}=l_{AK},b_{AKij}=b_{AK},\\ {\rho }_{AKij}={\rho }_{AK},{\epsilon }_{Kij}={\epsilon }_K,T_{Kij}=T_K,l_{Kij}=l_K,b_{Kij}=b_K,{\rho }_{Kij}={\rho }_K,{\epsilon }_{\mathrm{TO}Pij}={\epsilon }_{\mathrm{TO}P},T_{\mathrm{TO}Pij}=T_{\mathrm{TO}P},l_{\mathrm{TO}Pij}=l_{\mathrm{TO}P},b_{\mathrm{TO}Pij}=b_{\mathrm{TO}P},\\ {\rho }_{\mathrm{TO}Pij}={\rho }_{\mathrm{TO}P},{\epsilon }_{Pij}={\epsilon }_P,T_{Pij}=T_P,l_{Pij}=l_P,b_{Pij}=b_P,{\rho }_{Pij}={\rho }_P,(13)\end{array}$$

An analysis of relation (13) shows that the proposed criterion of temporal stability in the form of a time interval Δ (τ ₀₂ ) from the moment the voltage (or supply current) is turned on until the initial output signal of the test value U ₀₂ reaches the particular stability conditions (13), since only with the identity of the structures of thin-film strain gauges, the sizes and characteristics of their elements and transitions included in various shoulders of the NiMEMS bridge circuit, i.e. when the stability conditions are met, a minimum of the time interval Δ (τ ₀₂ ) is provided. In addition, only with the identity of the structures of thin-film strain gauges, the sizes and characteristics of their elements and junctions included in different shoulders of the NiMEMS bridge circuit, the error can be minimized under the influence of unsteady temperatures and increased vibration accelerations. Therefore, the proposed stability criterion provides a pass to the further assembly of NiMEMS with minimized error under the influence of unsteady temperatures and increased vibration accelerations. An advantage of the proposed criterion is also an increase in the technological effectiveness of forecasting due to a decrease in forecasting time and the absence of direct contact with NiMEMS and the negative impact of the environment and personnel on it due to the possibility of carrying out work in conditions meeting the requirements of nano- and microelectronic production. The implementation of the proposed method in the production of strain gauge pressure sensors based on thin-film NiMEMS provides increased temporary stability when exposed to influencing factors at relatively low cost, which allows to accordingly increase the life and service life of the sensors.

Thus, the technical result of the present invention is to increase the temporal stability, resource, service life, reduce the error under the influence of unsteady temperatures and increased vibration acceleration, as well as increase the technological effectiveness of forecasting due to more accurate and quick identification at the early stages of manufacturing potentially unstable NIMEMS with an imperfect structure with taking into account the influence of all elements of the NiMEMS bridge measuring circuit used to connect the strain gauges to the bridge KSR Control circuit and a supply circuit and converting the output signal.

Information sources

1. RU patent No. 2095772, C1, G01L 9/04. Pressure sensor and method of its manufacture. Publ.: November 10, 1997 BI No. 6.

2. RU patent No. 2423678, C1, G01L 9/00. A method of manufacturing a thin film pressure sensor. Published: 07/10/2011, BI No. 19.

Claims (1)

A method of manufacturing a strain gauge pressure sensor based on a thin-film nano- and microelectromechanical system (NiMEMS), which consists in polishing the surface of the membrane, forming a dielectric film and strain gauges on it with low resistance jumpers and contact pads between them using a strain gauge layer pattern having the configuration of the strain gauges in the zones combined with low-resistance jumpers and contact pads, in the form of strips including images of strain elements and their continuation in two opposite directions, and in areas compatible with the contact pads - partially coinciding with the configuration of the contact pads and sections remote from the strips, connecting the lead conductors to the contact pads in areas remote from the strip strips, characterized in that after connecting the lead conductors to contact pads of NiMEMS strain elements include the voltage (or supply current) of NiMEMS and can withstand for the time necessary to establish the initial output signal to
$$U_{01}=U_{00}\pm \Delta (U_{01}),$$

where U ₀₀ is the value of the initial output signal NIMEMS;
$$\Delta (U_{01})$$

- permissible fluctuation of the initial output signal;
they turn off the voltage (or supply current) and after holding NiMEMS in the off state for a time sufficient to return NiMEMS to the state preceding the voltage (or supply current) was turned on, turn on the voltage (or supply current) and determine the time interval Δ (τ ₀₂ ) from the moment the voltage (or supply current) is turned on until the initial output signal of the test value is reached
$$U_{02}=U_{00}\pm \Delta (U_{02}),$$

$$\Delta (U_{02})={\gamma }_0{\text{U}}_{\text{H}}$$

- permissible deviation of the value of the initial output signal U ₀₂ ;
γ ₀ is the basic error of the sensor;
U _H is the nominal output signal of the sensor,
and if the time interval Δ (τ ₀₂ ) from the moment the voltage (or supply current) is turned on until the initial output signal reaches the test value U ₀₂ does not exceed the maximum permissible value, which is taken as a criterion of temporary stability and is determined experimentally from statistics for a specific size sensor, then this assembly is passed on to subsequent operations.

Images