CN208192128U - A kind of MEMS euthermic chip integrating multiple Pt film resistor temperature sensors - Google Patents

Abstract

The utility model discloses a MEMS heating chip integrating a plurality of Pt thin film resistance temperature sensors, comprising: a first substrate (1‑1), a concave microcavity (2) on the front; the microcavity (2) There are micro-through holes (3) through the first substrate (1-1) inside; the second substrate (1-2) has a micro-channel array (4) perpendicular to the back of the second substrate, and a central area of the front is set There is a porous structure (5) perpendicular to its front, and the microfluidic channel array (4) communicates with the porous structure (5); there are a plurality of Pt thin film resistance temperature sensors (6) on its front surface; the first substrate (1-1 ) is glued together with the back side of the second substrate (1-2). The heating chip of the utility model can measure the temperature of the heating chip in real time, effectively avoiding problems such as inaccurate temperature measurement.

Description

A MEMS heating chip integrating multiple Pt thin film resistance temperature sensors

technical field

The utility model relates to the technical field of electronic cigarettes, in particular to a MEMS electronic cigarette heating chip integrating a plurality of Pt thin film resistance temperature sensors.

Background technique

Most commercially available e-cigarettes use a heating wire as a heating element. In the power supply state, the heating wire heats the e-liquid through the high heat generated by electrothermal conversion to atomize it. Due to the spiral structure of the heating wire itself and the way the oil guide is wound on it, it is inevitable that the heating wire will experience local high temperature during operation. E-liquid components and oil-conducting materials will change in physical and chemical properties when the temperature of the e-cigarette is too high, and harmful cracking products may be produced; at high temperatures, some aroma components in the e-liquid will be destroyed, affecting the richness of the flavor; Excessively high smoke temperature will also cause excessively high temperature of the smoke generated by atomization, which may cause damage to the respiratory tract; in the case of insufficient supply of liquid smoke, the excessively high temperature will also burn the atomizing core (fuzzy core), resulting in paste. taste, and the vaping experience becomes worse.

In order to improve the above defects, in recent years, temperature control technology has appeared in electronic cigarettes. The basic principle of this temperature control technology is: the electronic cigarette temperature control chip monitors the temperature of the heating wire by reading the resistance of the heating wire. The heating wire is essentially a resistance wire. When the temperature of the heating wire rises, the number of collisions between metal ions inside the heating wire increases, and the resistivity of the metal changes with temperature. The temperature and resistance are related by the temperature coefficient of resistance. couplet. Specifically, the electronic cigarette has a built-in heating wire resistance detection circuit, which allows users to set the maximum temperature of the heating wire according to their own preferences. The reference resistance of the heating wire is measured at room temperature in order to determine the correct temperature related to the reference resistance value, and then, the operating temperature of the electronic cigarette is estimated by continuously measuring the resistance value when the electronic cigarette is started and applying the resistance-temperature formula. Through the specific algorithm of the temperature control chip, the output power of the battery is adjusted so that the resistance of the heating wire does not exceed the calculated value corresponding to the temperature set by the user. At present, the commonly used temperature control heating wire types mainly include nickel 200, titanium and 316 stainless steel wire. The advantage of this technology is that the heating wire will not be overheated or dry-burned, and it also avoids the odor and harmful substances produced by the high evaporation temperature of the e-liquid, which greatly improves the overall experience and safety of e-cigarettes.

At present, the "temperature control" applied to electronic cigarettes is actually based on the change of the resistance value of the metal to convert the corresponding temperature to realize the so-called "temperature control", which is finally realized based on the resistance change of the heating wire. This temperature control method does not use a temperature sensor to detect the temperature, but calculates the temperature information through the electronic cigarette host chip to calculate the change of the resistance of the heating wire. Therefore, in fact, the current temperature control of the electronic cigarette is based on the change of the resistance of the heating wire The basis is not judged by the actual temperature. As a result, the accuracy of the temperature is directly related to the accuracy of the resistance value. If the initial resistance value detected by the chip is not accurate, the temperature calculated according to the temperature coefficient of resistance will not be Exactly, if the base is wrong, the whole calculation is wrong. In addition, this temperature control method still has the following problems: the resistance value of the heating wire can only reflect the overall temperature situation, and when the local temperature is too high, it cannot be effectively monitored; secondly, during use, the heating wire will be aging due to high temperature, Oxidation and other reasons lead to changes in resistance, which will lead to larger and larger temperature measurement errors.

Among the many temperature measurement methods, the resistance temperature sensor (or resistance temperature detector, usually referred to as RTD) is one of the most accurate methods, and the advantage of the thin film resistance temperature sensor compared with the traditional RTD is high sensitivity and fast thermal response, which is Because of its smaller size reduces heat exchange between sensitive components and the environment. Platinum (Pt) metal is the material of choice for thin-film resistive temperature sensors due to its good response to heat, highly linear positive correlation between resistivity and temperature, and long-term chemical stability at high temperatures. At present, most Pt thin-film resistance temperature sensors can be prepared on silicon or metal substrates by CMOS (complementary metal oxide semiconductor) technology or MEMS (micro-electromechanical system) technology. The use of Pt in MEMS devices in particular allows the fabrication of structures that are highly resistant to plastic deformation at elevated temperatures.

Utility model content

The purpose of the utility model is to solve the problems existing in the existing electronic cigarette temperature control technology, and adopt advanced MEMS processing technology to design a MEMS electronic cigarette heating chip with integrated temperature sensor and its manufacturing method. Through the integrated temperature sensor, the temperature of the MEMS heating chip can be accurately measured in real time, and with the external temperature controller, the accurate control of the MEMS heating chip can be realized, so that the smoke liquid can be evenly atomized.

The first aspect of the utility model discloses a MEMS heating chip integrating multiple Pt thin film resistance temperature sensors, including:

The first substrate (1-1) is in the shape of a sheet, and has a concave microcavity (2) on its front; the microcavity (2) has a microscopic cavity penetrating through the first substrate (1-1). through hole (3);

The second substrate (1-2), in sheet shape, has a microfluidic channel array (4) perpendicular to its backside on its back side, and a porous structure (5) perpendicular to its front side is provided in the front central area, and the microfluidic The channel array (4) communicates with the porous structure (5); there are multiple Pt thin film resistance temperature sensors (6) on its front surface;

The front side of the first substrate (1-1) is glued together with the back side of the second substrate (1-2).

Preferably, the depth of the microcavity (2) is 1 mm to 5 mm; the diameter of the micro through hole (3) is 500 microns to 1 mm.

Preferably, there is a metal film on the front side of the second substrate (1-2), and the thickness of the metal film is 200-500nm; the sputtered metal film material is one of Ti/Pt or Cr/Pt or several.

Preferably, the diameter of the micro-channels of the micro-channel array (4) is 10 microns to 500 microns, and the depth of the micro-channels is 1/2 to 1/2 of the height of the second substrate (1-2). 3/4.

Preferably, the pore diameter of the porous structure (5) is 100 nm to 1000 nm.

Preferably, the first substrate is made of glass or high-resistance single-crystal silicon, and the resistivity of the high-resistance single-crystal silicon is greater than 10Ω·cm.

Preferably, the second substrate is made of low-resistance single-crystal silicon, and the resistivity of the low-resistance single-crystal silicon is less than 0.01Ω·cm.

The second invention of the utility model discloses a method for preparing a MEMS heating chip integrating a plurality of Pt thin film resistance temperature sensors, comprising the following steps:

Preparation of the first substrate (1-1):

(1) Photolithographically form a microcavity pattern on the front surface of a glass sheet or a high-resistance single crystal silicon wafer with a resistivity greater than 10Ω cm, and then use an etching solution to etch the microcavity (2);

(2) photolithography is carried out to the back side of the glass sheet or the high-resistance monocrystalline silicon wafer obtained in step (1), and then adopt the etching solution to corrode the micro-vias (3 ); That is, obtain the first substrate (1-1);

Preparation of the second substrate (1-2):

(a) photoetching the back of a silicon wafer with a low resistivity of less than 0.01Ω·cm to form a microchannel array pattern;

(b) Etching the back side of the low-resistivity silicon wafer in step (a) by using a deep reactive ion etching process to form a microchannel array (4);

(c) using a low-pressure chemical vapor deposition process to deposit a layer of silicon nitride on the front side of the low-resistivity silicon wafer obtained in step (b);

(d) performing photolithography on the front side of the low-resistivity silicon wafer obtained in step (c), and removing the exposed silicon nitride layer in the middle by a reactive ion etching process;

(e) using an electrochemical etching process to corrode a porous structure (5) on the front side of the low-resistivity silicon wafer obtained in step (d), so that the porous structure communicates with the microchannel array on the back;

(f) photolithography on the front side of the low-resistivity silicon wafer obtained in step (e), and magnetron sputtering deposition to form a metal film;

(g) carrying out spin-coating photoresist photolithography on the front side of the silicon wafer of the sputtered metal thin film obtained in step (f), forming a temperature sensor pattern;

(h) dry etching the metal film exposed in step (g), leaving the desired metal film pattern;

(i) remove the remaining photoresist on the surface of step (h) with acetone;

(j) sputtering an aluminum oxide layer on the front surface of the silicon wafer from which the photoresist was removed in (i);

(K) Spin-coat photoresist photolithography again on the surface of the aluminum oxide layer described in (j) and dry etch the exposed aluminum oxide layer;

(l) After removing (k) residual photoresist with acetone, it is the second substrate (1-2)

Preparation of MEMS heating chip integrating multiple Pt thin film resistance temperature sensors:

(A) The front side of the first substrate (1-1) is in close contact with the back side of the second substrate (1-2), and bonded together by bonding process;

(B) using a dicing machine to scribe the chip obtained in step (a);

(c) The front side of the second substrate of the chip dicing obtained in step (b) is bonded to the wire with silver paste, then sintered at a high temperature, and then naturally cooled to room temperature to obtain the MEMS integrating multiple Pt thin film resistance temperature sensors. Heat chip.

Preferably, the etching solution described in step (1) or (2), wherein the etching solution for the glass sheet is hydrofluoric acid solution, and the etching solution for the high-resistance single crystal silicon wafer is potassium hydroxide solution or tetramethylammonium hydroxide One of the solutions.

Preferably, the material of the metal thin film sputtered in step (f) is one or more of Ti/Pt or Cr/Pt.

Preferably, the high temperature in step (c) is 300-700° C., and the sintering time is 10-20 minutes.

Beneficial results of the utility model:

(1) The utility model uses a MEMS heating chip integrated with multiple Pt thin film resistance temperature sensors to measure the temperature of the electronic cigarette heating chip in real time. The temperature measurement is accurate, the sensor has a long life and reliable operation, and effectively avoids the existing electronic cigarette heating element. Problems such as inaccurate temperature measurement and aging of the heating element lead to constant changes in the temperature measuring resistance; the chip can be controlled in real time to avoid overheating; the second is to adjust the temperature according to user needs, thereby changing the amount of atomization and the dispersion effect of smoke liquid Well, the heating is uniform, which can effectively increase the heat utilization rate and improve the atomization effect.

(2) The utility model can set a plurality of platinum resistance temperature sensors according to actual needs, and carry out distributed measurement on the surface temperature of the chip to obtain the temperature distribution of different regions of the chip, which can avoid the problem that the existing method cannot measure the local temperature of the heating element .

Description of drawings

Fig. 1 is the side sectional view of the MEMS heating chip integrating a plurality of Pt thin film resistance temperature sensors of the present utility model;

Fig. 2 is a side sectional view of the first substrate of the present invention;

Fig. 3 side sectional view of the second substrate;

Fig. 4 the front top view of the second substrate;

Fig. 5 is a top view of the back of the second substrate.

Reference numerals are: 1-1, first substrate; 1-2, second substrate; 2, microcavity; 3, micro-through hole; 4, micro-channel display; 5, porous structure; 6, Pt Temperature sensor; 7, silicon nitride layer; 8, Al ₂ O ₃ layer.

Detailed ways

The first aspect of the utility model discloses a MEMS heating chip integrating multiple Pt thin film resistance temperature sensors, including:

The first substrate (1-1) is in the shape of a sheet, and has a concave microcavity (2) on its front; the microcavity (2) has a microscopic cavity penetrating through the first substrate (1-1). through hole (3);

The second substrate (1-2), in sheet shape, has a microfluidic channel array (4) perpendicular to its backside on its back side, and a porous structure (5) perpendicular to its front side is provided in the front central area, and the microfluidic The channel array (4) communicates with the porous structure (5); there are multiple Pt thin film resistance temperature sensors (6) on its front surface;

The front side of the first substrate (1-1) is glued together with the back side of the second substrate (1-2).

The depth of the microcavity (2) is 3 mm; the diameter of the micro through hole (3) is 750 microns.

There is a metal film on the front side of the second substrate (1-2), and the thickness of the metal film is 350nm; the material of the metal film is Ti/Pt/Au.

The diameter of the micro-channels of the micro-channel array (4) is 35 microns, and the depth of the micro-channels is 1/2 of the height of the second substrate (1-2).

The pore diameter of the porous structure (5) is 500 nanometers.

The first substrate is made of glass or high-resistance single-crystal silicon, and the resistivity of the high-resistance single-crystal silicon is 20 Ω·cm.

The second substrate is made of low-resistance single-crystal silicon, and the resistivity of the low-resistance single-crystal silicon is 0.005Ω·cm.

A method for preparing a MEMS heating chip integrating a plurality of Pt thin film resistance temperature sensors is as follows:

Preparation of the first substrate (1-1):

(1) Form microcavity figure by photolithography on the front side of the high-resistance monocrystalline silicon wafer with resistivity 20Ω·cm, then adopt corrosion solution as potassium hydroxide solution to corrode the microcavity (2);

(2) Photolithography is performed on the back of the high-resistance monocrystalline silicon wafer obtained in step (1), and then a potassium hydroxide solution is used to etch out the micro-through holes that run through the glass sheet or the high-resistance monocrystalline silicon wafer. (3); That is, obtain the first substrate (1-1);

Preparation of the second substrate (1-2):

(a) photolithographically forming a microchannel array pattern on the back of a silicon wafer with a low resistivity of 0.005Ω·cm;

(b) Etching the back side of the low-resistivity silicon wafer in step (a) by using a deep reactive ion etching process to form a microchannel array (4);

(c) using a low-pressure chemical vapor deposition process to deposit a layer of silicon nitride on the front side of the low-resistivity silicon wafer obtained in step (b);

(d) performing photolithography on the front side of the low-resistivity silicon wafer obtained in step (c), and removing the exposed silicon nitride layer in the middle by a reactive ion etching process;

(e) using an electrochemical etching process to corrode a porous structure (5) on the front side of the low-resistivity silicon wafer obtained in step (d), so that the porous structure communicates with the microchannel array on the back;

(f) Lithography on the front side of the low-resistivity silicon wafer obtained in step (e), magnetron sputtering deposition to form a Ti/Pt metal film;

(g) carry out spin-coating photoresist lithography on the front side of the silicon wafer sputtered with metal thin film obtained in step (f), to form a temperature sensor pattern;

(h) using dry etching step (g) exposed metal film, leaving the required metal film pattern;

(i) remove the remaining photoresist on the surface of step (h) with acetone;

(j) sputtering an aluminum oxide layer on the front surface of the silicon wafer from which the photoresist was removed in (i);

(K) Spin-coat photoresist photolithography again on the surface of the aluminum oxide layer described in (j) and dry etch the exposed aluminum oxide layer;

(l) After removing (k) residual photoresist with acetone, it is the second substrate (1-2)

Preparation of MEMS heating chip integrating multiple Pt thin film resistance temperature sensors:

(A) The front side of the first substrate (1-1) is in close contact with the back side of the second substrate (1-2), and bonded together by bonding process;

(B) using a dicing machine to scribe the chip obtained in step (a);

(c) Bond the front side of the second substrate of the chip obtained in step (b) with silver paste and sinter at 600°C for 10 minutes, then cool naturally to room temperature to obtain the integrated multiple Pt thin film resistance temperature The MEMS heating chip of the sensor.

Claims (5)

1. A MEMS heating chip integrating a plurality of Pt thin film resistance temperature sensors, is characterized in that, comprising: The first substrate (1-1) is sheet-shaped, and has a concave microcavity (2) on its front; microcavities (2) that penetrate the first substrate (1-1) are provided. A through hole (3); the first substrate is made of glass or high-resistance single-crystal silicon, and the resistivity of the high-resistance single-crystal silicon is greater than 10Ω·cm; The second substrate (1-2), in sheet shape, has a microfluidic channel array (4) perpendicular to its backside on its back side, and a porous structure (5) perpendicular to its front side is provided in the front central area, and the microfluidic The channel array (4) communicates with the porous structure (5); there are a plurality of Pt thin film resistance temperature sensors (6) on its front surface; the second substrate is made of low-resistance single-crystal silicon, and the low-resistance single-crystal silicon The resistivity is less than 0.01Ω·cm; The front side of the first substrate (1-1) is glued together with the back side of the second substrate (1-2). 2. the MEMS heating chip of integrating a plurality of Pt thin film resistance temperature sensors according to claim 1, is characterized in that, the depth of described microcavity (2) is 1 millimeter to 5 millimeters; Described microthrough hole (3 ) has a diameter of 500 microns to 1 mm. 3. the MEMS heating chip of integrating a plurality of Pt thin film resistance temperature sensors according to claim 1, is characterized in that, the front side of described second substrate (1-2) has metal thin film, and the thickness of described metal thin film is 200-500 nm; the material of the metal thin film is one or more of Ti/Pt/Au, TiW/Au, Al, Cr or Pt/Au. 4. the MEMS heating chip of integrating a plurality of Pt thin film resistance temperature sensors according to claim 1, is characterized in that, the diameter of the microchannel of described microchannel array (4) is 10 microns to 500 microns, and described The depth of the micro-channel is 1/2-3/4 of the height of the second substrate (1-2). 5. The MEMS heating chip integrating a plurality of Pt thin film resistance temperature sensors according to claim 1, characterized in that, the aperture of the porous structure (5) is 100 nanometers to 1000 nanometers.