CN108185526B - MEMS heating chip integrated with diode temperature sensor and manufacturing method thereof - Google Patents

Abstract

The invention discloses a MEMS heating chip integrated with a diode temperature sensor, comprising: a first substrate (1‑1), in the shape of a sheet, with a concave microcavity (2) on the front; the microcavity (2) ) has a micro-through hole (3) that runs through the first substrate (1-1) at the center; the second substrate (1-2) is sheet-shaped, and its back has micro-channels perpendicular to its back Array (4), the central area of the front is provided with a porous structure (5) perpendicular to its front, and the microfluidic channel array (4) communicates with the porous structure (5); there are metal lead pads (6) on its front edge; There is a diode temperature sensor (7) on the front surface; the front surface of the first substrate (1-1) is glued to the back surface of the second substrate (1-2). The invention also discloses a preparation method of the MEMS heating chip integrated with a diode temperature sensor.

Description

MEMS heating chip with integrated diode temperature sensor and manufacturing method thereof

technical field

The invention relates to the technical field of electronic cigarettes, in particular to a MEMS electronic cigarette heating chip integrated with a diode temperature sensor and a manufacturing method thereof.

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 make the smoke generated by atomization too high, which may cause damage to the respiratory tract; in the case of insufficient supply of smoke liquid, the excessively high temperature will also burn the atomizing core (burnt core), resulting in paste. smell, 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 by calculating the resistance change of the heating wire through the main chip of the electronic cigarette. Therefore, in fact, the current temperature control of the electronic cigarette is based on the resistance change 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 based on 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. Metallic platinum (Pt) 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.

Another type of temperature sensor is the heating diode. Among them, the silicon p-n junction diode is the most accurate temperature sensor, which can be used to sense the temperature according to its strong correlation between the forward bias voltage and the temperature. Due to its sensitive and accurate temperature measurement and absolute temperature measurement, simple voltage-temperature relationship in a wide temperature range, compatibility with integrated circuit technology (especially integrated with electronic devices on the same chip) and It is widely used in temperature measurement due to its low manufacturing cost. In high temperature applications, silicon diodes provide thermal feedback to accurately control the temperature of the heating element (or micro-heating device). When operating in constant current mode, silicon diodes can measure temperatures from -200°C to 850°C.

Contents of the invention

The purpose of the present invention 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 an integrated temperature sensor and a manufacturing method thereof. 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 present invention discloses a MEMS heating chip integrating a diode temperature sensor, comprising:

The first substrate 1-1 is sheet-shaped, and has a concave microcavity 2 on its front; the center of the microcavity 2 has a micro through hole 3 that runs through the first substrate 1-1;

The second substrate 1-2 is in the shape of a sheet, and its back has a microfluidic channel array 4 perpendicular to its back, and the central area of the front is provided with a porous structure 5 perpendicular to its front, and the microfluidic channel array 4 is connected to the porous structure. 5 connected; its front edge has a metal lead pad 6; its front surface has a diode temperature sensor 7;

The front side of the first substrate 1-1 is bonded to 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 200-500 nm; the material of the metal film is Ti/Pt/Au.

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˜3/4 of the height of the second substrate 1-2.

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 aspect of the present invention discloses a method for preparing a MEMS heating chip integrating a diode temperature sensor, 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) Perform photolithography on the back of the glass sheet or high-resistance single-crystal silicon wafer in step (1), and then use an etching solution to etch out the micro-vias penetrating through the glass sheet or high-resistance single-crystal silicon wafer; that is, the obtained The first substrate 1-1 described above;

Preparation of the second substrate 1-2:

(a) Photolithographically forming a micro-channel array pattern on the back of a low-resistivity silicon wafer with a resistivity less than 0.01Ω·cm;

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

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

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

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

(f) using LPCVD or sputtering to fabricate an n-type silicon thin film on the front side of the silicon wafer in step (e);

(g) removing excess silicon film from step (f) by reactive ion etching;

(h) locally heavily doping the silicon film of step (g) so as to form an ohmic contact;

(i) sputtering metal thin film, using stripping process to fabricate diode leads and metal lead pads 6 to obtain diode temperature sensor 7; that is, the second substrate 1-2;

Preparation of MEMS electronic cigarette heating chip with integrated diode temperature sensor:

(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 dice the chip obtained in step (A) to obtain the MEMS heating chip integrated with a diode temperature sensor.

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

Preferably, the material of the step (i) sputtering the metal thin film is Ti/Pt/Au.

Preferably, the diode temperature sensor 7 is a Schottky diode temperature sensor, which includes an n-type silicon thin film 9 as a base, an n-type heavily doped region 10 and a metal lead 12 that together form the cathode of the diode, and a Schottky diode as the anode. The tertiary contacts the electrode 11 .

(1) A MEMS heating chip with an integrated diode temperature sensor of the present invention uses an integrated silicon diode temperature sensor to measure the temperature of the electronic cigarette heating chip in real time, one is to avoid overheating; the other is to adjust the temperature according to user needs, thereby changing atomization amount. The temperature measurement is accurate, the sensor has a long service life and reliable operation, which effectively avoids the problems of inaccurate temperature measurement of the heating element of the existing electronic cigarette, aging of the heating element and constant changes in the temperature measuring resistance;

(2) The present invention can set one or more silicon diode temperature sensors according to actual needs, and perform distributed measurement on the surface temperature of the chip to obtain the temperature distribution in different regions of the chip, which can avoid the failure of the existing method to measure the local temperature of the heating element question. It can effectively improve the heat utilization rate and improve the atomization effect of the e-liquid.

(3) The preparation method of the present invention is simple, the process is standard, and is suitable for mass production.

Description of drawings

Fig. 1 is the side sectional view of the MEMS heating chip of integrated diode temperature sensor of the present invention;

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 signs are: 1-1, first substrate; 2, microcavity; 3, micro through hole; 4, microchannel array; 5, porous structure; 6, metal lead pad; 7, diode temperature sensor ; 8, silicon nitride layer; 9, n-type silicon thin film; 10, n-type heavily doped region; 11, Schottky contact electrode; 12, metal lead.

Implementation

A kind of MEMS heating chip of integrated diode temperature sensor of the present invention comprises:

The first substrate 1-1 is sheet-shaped, and has a concave microcavity 2 on its front; the center of the microcavity 2 has a micro through hole 3 that runs through the first substrate 1-1;

The second substrate 1-2 is in the shape of a sheet, and its back has a microfluidic channel array 4 perpendicular to its back, and the central area of the front is provided with a porous structure 5 perpendicular to its front, and the microfluidic channel array 4 is connected to the porous structure. 5 connected; its front edge has a metal lead pad 6; its front surface has a diode temperature sensor 7;

The front side of the first substrate 1-1 is bonded to 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 thin film on the front side of the second substrate 1-2, and the thickness of the metal thin film is 300nm; the material of the metal thin film is Ti/Pt/Au.

The diameter of the micro-channels of the micro-channel array 4 is 100 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 high-resistance single-crystal silicon, and the resistivity of the high-resistance single-crystal silicon is 20Ω·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 kind of preparation method of the MEMS heating chip of integrated diode temperature sensor of the present invention, comprises the following steps:

Preparation of the first substrate 1-1:

(1) Photolithographically form a microcavity pattern on the front surface of a high-resistance single crystal silicon wafer with a resistivity greater than 20Ω·cm, and then use an etching solution potassium hydroxide solution to etch the microcavity;

(2) Perform photolithography on the back of the high-resistance single-crystal silicon wafer in step (1), and then use an etching solution, potassium hydroxide solution, to etch out micro-vias that run through the high-resistance single-crystal silicon wafer; first substrate 1-1;

Preparation of the second substrate 1-2:

(a) Forming microchannel array patterns by photolithography on the back of a low-resistivity silicon wafer with a resistivity of 0.005Ω·cm;

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

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

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

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

(f) using LPCVD or sputtering to fabricate an n-type silicon thin film on the front side of the silicon wafer in step (e);

(g) removing excess silicon film from step (f) by reactive ion etching;

(h) locally heavily doping the silicon film of step (g) so as to form an ohmic contact;

(i) sputtering metal thin film, the material is Ti/Pt/Au, using the stripping process to make diode leads and metal lead pads 6, to obtain a diode temperature sensor 7; the diode temperature sensor 7 is a Schottky diode temperature sensor, which It includes an n-type silicon thin film 9 as a base, an n-type heavily doped region 10 and a metal lead 12 that together form the cathode of the diode, and a Schottky contact electrode 11 as the anode of the diode; that is, the second substrate 1-2.

Preparation of MEMS electronic cigarette heating chip with integrated diode temperature sensor:

(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 dice the chip obtained in step (A) to obtain the MEMS heating chip integrated with a diode temperature sensor.

Claims (5)

1. A MEMS heating chip of integrated diode temperature sensor, is characterized in that, comprises: The first substrate (1-1) is sheet-shaped, and has a concave microcavity (2) on the front; the center of the microcavity (2) has a penetrating through the first substrate (1-1) The micro-via (3); the depth of the micro-cavity (2) is 1 mm to 5 mm; the diameter of the micro-via (3) is 500 microns to 1 mm; the first substrate is glass Or made of high-resistance single-crystal silicon, the resistivity of said high-resistance single-crystal silicon is greater than 10Ω·cm; The second substrate (1-2) is in the form of a sheet, with a microfluidic channel array (4) perpendicular to the back of the substrate, and a porous structure (5) perpendicular to the front central area of the front, the microfluidic The channel array (4) communicates with the porous structure (5); there are metal lead pads (6) on the front edge; there is a diode temperature sensor (7) on the front surface; the diode temperature sensor (7) is a Schottky diode temperature The sensor includes an n-type silicon thin film (9) as a base, an n-type heavily doped region (10) and a metal lead (12) that together form the cathode of the diode, and a Schottky contact electrode (11) as the anode of the diode; There is a metal film on the front of the second substrate (1-2), the thickness of the metal film is 200-500nm; the material of the metal film is Ti/Pt/Au; the microchannel array (4) The diameter of the micro-channel is 10 microns to 500 microns, and the depth of the micro-channel is 1/2 to 3/4 of the height of the second substrate (1-2); the pore diameter of the porous structure (5) is 100 nanometers to 1000 nanometers; 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 front side of the first substrate (1-1) is glued together with the back side of the second substrate (1-2). 2. a method for preparing a MEMS heating chip of an integrated diode temperature sensor, is characterized in that, comprises 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) Perform photolithography on the back of the glass sheet or high-resistance single-crystal silicon wafer in step (1), and then use an etching solution to etch out the micro-vias penetrating through the glass sheet or high-resistance single-crystal silicon wafer; that is, the obtained the first substrate (1-1); Preparation of the second substrate (1-2): (a) Photolithographically forming a micro-channel array pattern on the back of a low-resistivity silicon wafer with a resistivity less than 0.01Ω·cm; (b) Etching the back of the low-resistivity silicon wafer in step (a) by using a deep reactive ion etching process to form a microchannel array; (c) Depositing a layer of silicon nitride on the front side of the low-resistivity silicon wafer described in step (b) by using a low-pressure chemical vapor deposition process; (d) performing photolithography on the front side of the low-resistivity silicon wafer described in step (c), and removing the exposed silicon nitride layer in the middle by a reactive ion etching process; (e) Corroding a porous structure on the front side of the low-resistivity silicon wafer obtained in step (d) by using an electrochemical etching process, so that the porous structure communicates with the microchannel array on the back side; (f) using LPCVD or sputtering to fabricate an n-type silicon thin film on the front side of the silicon wafer in step (e); (g) removing excess silicon film from step (f) by reactive ion etching; (h) locally heavily doping the silicon film of step (g) so as to form an ohmic contact; (i) Sputtering a metal film, using a lift-off process to fabricate diode leads and metal lead pads (6), to obtain a diode temperature sensor (7); that is, the second substrate (1-2); Preparation of MEMS electronic cigarette heating chip with integrated diode temperature sensor: (A) bringing the front side of the first substrate (1-1) into close contact with the back side of the second substrate (1-2), and bonding them together through a bonding process; (B) Using a dicing machine to dice the chip obtained in step (A) to obtain the MEMS heating chip integrated with a diode temperature sensor. 3. The preparation method according to claim 2, characterized in that, the etching solution described in step (1) or (2), wherein the etching solution for the glass sheet is a hydrofluoric acid solution, the etching of the high-resistance single crystal silicon sheet The solution is one of potassium hydroxide solution or tetramethylammonium hydroxide solution. 4 . The preparation method according to claim 2 , wherein the material of the sputtering metal thin film in the step (i) is Ti/Pt/Au. 5. The preparation method according to claim 2, characterized in that, the diode temperature sensor (7) is a Schottky diode temperature sensor, which includes an n-type silicon thin film (9) as a substrate, and a The n-type heavily doped region (10), the metal lead (12) and the Schottky contact electrode (11) as the anode of the diode.