CN106976837A - Microheater and its processing method - Google Patents

Abstract

The invention discloses a micro-heater and a processing method thereof. The micro-heater comprises: a substrate, a supporting film, a heating element and an encapsulation shell. The substrate has a first surface and a second surface opposite to each other along its thickness direction, the substrate is provided with a heat-insulating through-hole passing through it in the thickness direction, and the substrate is provided with a ventilation structure communicating with the heat-insulating through-hole and the outside world , the support film is arranged on the first surface of the substrate and covers the first end of the heat insulation through hole, the heating element is arranged on the surface of the support film away from the heat insulation through hole, and the package shell is arranged on the second surface of the substrate and cap the second end of the thermal isolation via. According to the micro heater of the present invention, by setting the ventilation structure communicating with the heat insulation through hole and the outside world on the substrate, thus when the micro heater is working, the chamber defined by the heat insulation through hole, the support film and the packaging shell and the The external communication prevents the problem that the device is easily damaged due to the pressure difference between the inside and outside of the chamber.

Description

Micro heater and its processing method

technical field

The invention relates to the technical field of micro-electro-mechanical systems, in particular to a micro-heater and a processing method thereof.

Background technique

In related technologies, the structure of the surface micro-heater mainly includes a closed membrane structure and a cantilever beam structure. The power consumption of the cantilever beam structure is lower than that of the closed membrane structure, and the cantilever beam structure will cause thermal stress release due to the composite membrane. The device undulates on the horizontal plane, and as the reaction temperature of the device increases, the composite film will be thermally expanded, which will increase the local concentration of thermal stress in the cantilever beam structure. The mechanical properties of the closed film are better, and the mechanical properties of the suspended film are worse, but the compatibility with the CMOS process is better. Because the mechanical strength of the closed film is better, and it is beneficial to the coating of subsequent sensitive materials and the improvement of the service life of subsequent sensors, most sensors use this design scheme.

However, in the long-term working process of the surface-type micro-heater with a closed membrane structure, the internal devices are prone to damage, which affects the actual use effect and reliability of the sensor.

Contents of the invention

The application is based on the inventor's discovery and understanding of the following facts and problems: the inventor has found through research that the surface micro heater with a closed membrane structure is damaged mainly by the material in the long-term work process. caused by fatigue fracture. Through further research and exploration by the inventors, it was found that the reason for the fatigue fracture of the device is that the gas pressure change in the micro-heated chamber of the closed membrane structure causes the supporting membrane to be affected by the pressure difference in addition to its own thermal stress. The resulting periodic/long-term pressure difference makes the support membrane prone to fatigue fracture under the action of periodic/long-term pressure difference.

The present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, the present invention proposes a micro heater, which has a simple structure, long service life and high reliability.

The present invention also proposes a processing method for the micro heater.

The micro heater according to the embodiment of the first aspect of the present invention includes: a substrate, the substrate has a first surface and a second surface oppositely arranged along its thickness direction, and The thermal insulation through hole, and the substrate is provided with a ventilation structure that communicates with the thermal insulation through hole and the outside world; a support film, the support film is provided on the first surface of the substrate and covers The first end of the heat insulation through hole; the heating element, the heating element is arranged on the surface of the support film away from the heat insulation through hole; the package shell, the package shell is set on the substrate The second end is on the second surface and covers the heat insulation through hole.

According to the micro-heater of the embodiment of the present invention, by providing a ventilation structure communicating with the heat-insulating through-hole and the outside world on the substrate, when the micro-heater is working, the cavity defined by the heat-insulating through-hole, the supporting film and the package shell The chamber communicates with the outside world, preventing the problem that the device is easily damaged due to the pressure difference between the inside and outside of the chamber.

According to some optional embodiments of the present invention, a groove is provided on the second surface of the substrate, and the ventilation structure is defined between the groove and the package case.

Optionally, there are multiple grooves arranged at intervals along the circumference of the heat insulation through hole.

Optionally, the cross section of the groove is arc-shaped or U-shaped.

According to some optional embodiments of the present invention, an end portion of the heat insulation through hole located on the first surface is formed in a circular shape.

Further, the cross-sectional area of the heat insulation through hole increases in a direction from the first surface to the second surface.

According to some optional embodiments of the present invention, the heating element is a heating resistance wire, and the curvature change of the heating resistance wire in its extending direction is continuous.

Optionally, the projection of the heating resistance wire on the support film is in the shape of a circle, an ellipse, an involute or a polygon with rounded corners at the vertices.

Optionally, the heating resistance wire includes a plurality of straight sections parallel to each other and arranged at intervals, and a bent section connecting two adjacent straight sections, and a junction between the bent section and the straight section transitions smoothly.

The method for processing a micro heater according to the embodiment of the second aspect of the present invention includes the following steps: S10, depositing and forming the support film on the first surface of the substrate; S20, disposing the support film on the support film The heating element; S30, etching the substrate from the second surface of the substrate along its thickness direction to form the heat insulation via hole, and etching the second surface of the substrate The substrate is used to form the groove; S40, using an adhesive to connect the encapsulation case to the substrate to encapsulate the internal components of the micro heater.

According to the processing method of the micro-heater of the embodiment of the second aspect of the present invention, the processing process is simple, easy to operate, and the molding quality is high.

According to some optional embodiments of the present invention, in the step S30, the step of etching the heat-insulating via hole and the groove is as follows: firstly, the first part of the substrate is formed by dry etching technology. The second surface of the substrate is etched on the second surface of the substrate to form the first part of the thermal insulation via hole, and the substrate is etched on the second surface of the substrate by using the above-mentioned dry etching technology. forming the first part of the groove; and then using wet etching technology to continue etching the substrate along the thickness direction of the substrate on the basis of the first part of the thermal insulation via hole to form the thermal insulation For a through hole, the above-mentioned wet etching technique is used to continuously etch the substrate on the basis of the first part of the groove to form the groove.

Optionally, the dry etching technique is deep reactive ion etching.

Optionally, the etchant of the wet etching technique is a mixed solution of polyethylene glycol octylphenyl ether and tetramethylammonium hydroxide.

Additional aspects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and comprehensible from the description of the embodiments in conjunction with the following drawings, wherein:

Fig. 1 is a partial three-dimensional structure diagram of a micro heater according to an embodiment of the present invention;

Fig. 2 is a partial three-dimensional structural view of another angle of the micro heater according to the embodiment of the present invention.

Reference signs:

The substrate 1, the first surface 11, the second surface 12, the thermal insulation through hole 13, the first segment 131, the second segment 132, the ventilation structure 14,

support membrane 2,

Heating element 3, straight section 31, curved section 32,

Electrode 4.

detailed description

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

In describing the present invention, it is to be understood that the terms "center", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", The orientation or positional relationship indicated by "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential" etc. is based on the orientation or position shown in the drawings The relationship is only for the convenience of describing the present invention and simplifying the description, but does not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, the features defined as "first" and "second" may explicitly or implicitly include one or more of these features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

In the description of the present invention, it should be noted that unless otherwise specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connected, or integrally connected; it can be mechanically connected or electrically connected; it can be directly connected or indirectly connected through an intermediary, and it can be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention in specific situations.

A micro heater according to an embodiment of the present invention is described below with reference to FIGS. 1 and 2 .

As shown in FIG. 1 and FIG. 2 , the micro heater according to the embodiment of the first aspect of the present invention includes: a substrate 1 , a supporting film 2 , a heating element 3 and an encapsulation shell (not shown in the figure). For example, the above-mentioned micro-heater can be a surface-type micro-heater, and the above-mentioned micro-heater can be applied in the field of sensors.

Specifically, the substrate 1 has a first surface 11 and a second surface 12 oppositely arranged along its thickness direction. When the substrate 1 is placed in a horizontal direction, the first surface 11 and the second surface 12 are the upper surface of the substrate 1 surface and subsurface. The substrate 1 is provided with a thermal insulation through hole 13 passing through it in the thickness direction, and the substrate 1 is provided with a ventilation structure 14 communicating with the thermal insulation via hole 13 and the outside world. Optionally, the substrate 1 may be a silicon substrate.

The support film 2 is arranged on the first surface 11 of the substrate 1 and covers the first end of the heat insulation through hole 13, the middle part of the support film 2 covers the first end of the heat insulation through hole 13, and the support film 2 adjacent to it Part of the outer periphery is supported on and connected to the substrate 1 . The supporting film 2 may be a silicon oxide film, a silicon nitride film, or a silicon oxide/silicon nitride composite film.

The heating element 3 is arranged on the surface of the supporting film 2 away from the heat insulating through hole 13 , and the supporting film 2 supports the heating element 3 and separates the heating element 3 from the heat insulating through hole 13 . Optionally, the heating element 3 may be in the shape of a wire, a sheet, or the like. An electrode 4 connected to the heating element 3 is also provided on the substrate 1 , and the electrode 4 can be arranged adjacent to the outer periphery of the substrate 1 . For example, when the substrate 1 is square, the electrodes 4 may be provided at four corners of the substrate 1 .

The encapsulation shell is arranged on the second surface 12 of the substrate 1 and covers the second end of the heat insulation through hole 13, and the second end and the first end of the heat insulation through hole 13 are respectively covered by the encapsulation shell and the support film 2, A cavity is jointly defined between the package shell, the support film 2 and the heat insulation through hole 13 .

It can be understood that, during the working process of the micro heater, the heating element 3 will generate heat, and the supporting film 2 separates the heating element 3 from the heat-insulating through hole 13. At this time, the two surfaces of the supporting film 2 bear different loads. One of the two surfaces of the supporting film 2 faces the heating element 3 and the other faces the above-mentioned chamber, so that the supporting film 2 will not only be affected by its own thermal stress, but also be subjected to a pressure difference caused by heat.

By setting the above-mentioned ventilation structure 14 on the substrate 1, the chamber can be communicated with the outside through the ventilation structure 14, thus when the micro heater is working, the gas pressure in the above-mentioned chamber and the gas pressure outside can be reduced The pressure difference makes the gas pressure in the above-mentioned chamber tend to be consistent with the gas pressure outside, so that the pressure difference on the supporting membrane 2 can be reduced, so that the pressure on both sides of the supporting membrane 2 tends to be consistent, thereby preventing the supporting membrane from 2. Due to the fatigue damage caused by periodic/long-term pressure difference, prolong the service life of the micro-heater and improve the reliability of the micro-heater.

According to the micro heater of the embodiment of the present invention, by setting the ventilation structure 14 on the substrate 1 that communicates with the heat insulating through hole 13 and the outside world, when the micro heater is working, the heat insulating through hole 13, the support film 2 and the The cavity defined by the package shell communicates with the outside world, preventing the problem that the device is easily damaged due to the pressure difference between the inside and outside of the cavity.

According to some optional embodiments of the present invention, referring to FIG. 2, a groove is provided on the second surface 12 of the substrate 1, and the groove can extend radially and penetrate through the inner wall of the heat-insulating through hole 13 and the inner wall of the substrate 1. A ventilation structure 14 is defined between the peripheral wall, the groove and the packaging shell. Therefore, by providing grooves on the second surface 12 of the substrate 1 , the processing and shaping of the ventilation structure 14 can be facilitated, and the ventilation structure 14 can be simplified.

Optionally, referring to FIG. 2 , there may be a plurality of grooves arranged at intervals along the circumference of the heat insulation through hole 13 . Thus, the gas in the chamber and the gas outside can be quickly and evenly circulated, so that the gas pressure in the chamber and the gas pressure outside can be more consistent, and at the same time, the gas pressure in each part of the chamber can be reduced. more uniform. For example, the above-mentioned multiple grooves can be arranged in a radial shape, thereby shortening the flow path of the gas and increasing the flow area of the gas, which can better make the pressure on both sides of the support membrane 2 tend to be consistent, which is more significant The pressure difference on the supporting membrane 2 is greatly reduced.

Optionally, the cross-section of the above-mentioned groove may be arc-shaped or U-shaped. Therefore, the structure of the groove is simple and easy to process and form, and at the same time, the inner wall surface of the groove is smoothed to avoid stress generation, and the reliability of the micro heater is further improved.

According to some optional embodiments of the present invention, referring to FIG. 1 and FIG. 2 , the end portion of the heat insulation through hole 13 located on the first surface 11 is formed in a circular shape, so that the part of the support film 2 that covers the heat insulation through hole 13 It is also circular, that is, the suspended part in the support film 2 is circular, so that the edge of the suspended part in the support film 2 can be smooth and continuous to avoid the appearance of convex corners, thereby preventing the support film 2 from The problem of stress concentration is solved, and the service life of the support film 2 and the reliability of the micro heater work are further improved. Optionally, the supporting film 2 may be circular or square as a whole.

Further, the cross-sectional area of the heat-insulating through hole 13 increases in the direction from the first surface 11 to the second surface 12 (refer to the direction from top to bottom in FIG. 2 ). Thus, the overall structural stability and strength of the micro-heater can be improved, and the chip density of the micro-heater can be increased at the same time.

For example, the heat insulating through hole 13 may be formed in a truncated cone shape.

For another example, referring to FIG. 2 , the heat insulating through hole 13 may include a first segment 131 and a second segment 132 with different inner diameters. The first segment 131 and the second segment 132 are all formed in a cylindrical shape, wherein the first segment 131 is adjacent to the partition On the first surface 11 of the thermal via 13 , the second segment 132 is adjacent to the second surface 12 of the thermal isolation via 13 , and the inner diameter of the first segment 131 is smaller than the inner diameter of the second segment 132 .

According to some optional embodiments of the present invention, referring to FIG. 1 , the heating element 3 may be a heating resistance wire, and the curvature change of the heating resistance wire in its extending direction is continuous. As a result, each part of the heating resistance wire is smoothly connected and transitioned, which can prevent structural stress concentration on the heating element 3 and further improve the reliability of the micro-heater.

For example, the projection of the heating resistance wire on the support film 2 can be in the shape of a circle, an ellipse, an involute or a polygon with rounded corners at the vertices.

For another example, referring to FIG. 1 , the heating resistance wire may include a plurality of straight sections 31 arranged parallel to each other at intervals and a bent section 32 connecting two adjacent straight sections 31 , and the junction between the bent section 32 and the straight section 31 transitions smoothly. Thus, the heating resistance wires can be evenly distributed on the support film 2, so that the micro heater can obtain a large area and high-quality temperature uniform area during operation.

Referring to Fig. 1 and Fig. 2, the method of processing the micro heater according to the embodiment of the second aspect of the present invention will be described below.

The processing method of the micro-heater according to the embodiment of the second aspect of the present invention includes the following steps:

S10 , depositing and forming a supporting film 2 on the first surface 11 of the substrate 1 . The above support film 2 can be deposited on the first surface 11 of the substrate 1 by chemical vapor deposition technology, and the support film 2 can be a composite film structure. For example, a silicon oxide/silicon nitride composite film may be deposited on the first surface 11 of the substrate 1 by using a low pressure chemical vapor deposition technique or a plasma enhanced chemical vapor deposition technique. Wherein, before depositing the supporting film 2 on the substrate 1, the first surface 11 and the second surface 12 of the substrate 1 can be polished, thus the connection strength and reliability between the supporting film 2 and the substrate 1 can be enhanced .

S20, arranging the heating element 3 on the support film 2, the heating element 3 can be deposited on the support film 2 by a sputtering process, for example, a magnetron sputtering method can be used. According to the design requirements, the heating element 3 is sputter-deposited on the support film 2 into a sheet or filament shape. The graphic shape of the heating element 3 can be circular, elliptical, involute, polygonal or serpentine with rounded corners at the apex. .

S30, etch the substrate 1 from the second surface 12 of the substrate 1 along its thickness direction (refer to the direction from bottom to top in FIG. The substrate 1 is etched to form grooves. The etching of the heat insulating through hole 13 and the groove can be performed simultaneously or successively (for example, the heat insulating through hole 13 can be etched first, and then the groove can be etched). Of course, simultaneous etching of the heat-insulating through hole 13 and the groove can improve processing efficiency.

S40, using an adhesive to connect the encapsulation shell to the substrate 1 to encapsulate the internal components of the micro heater. During encapsulation, an adhesive is applied on the encapsulation shell, and then the encapsulation shell is bonded to the second surface 12 of the substrate 1 . When applying the adhesive on the package, the thickness of the adhesive in the bonding area on the package can be uniform and less than the depth of the groove, so as to prevent the groove from being filled with the adhesive when the package is bonded to the substrate 1 The ventilation structure 14 of the micro heater is blocked.

According to the processing method of the micro-heater of the embodiment of the second aspect of the present invention, the processing process is simple, easy to operate, and the molding quality is high.

According to some optional embodiments of the present invention, in the above step S30, the step of etching the heat-insulating via hole 13 and the groove is as follows:

First use dry etching technology to etch the substrate 1 from the second surface 12 of the substrate 1 along its thickness direction to form the first part of the thermal insulation via hole 13, and use the above dry etching technology on the second surface 12 of the substrate 1. The substrate 1 is etched on the surface 12 to form a first portion of the recess.

On the basis of the first part of the thermal insulation via hole 13, wet etching technology is used to continue etching the substrate 1 along the thickness direction of the substrate 1 to form the thermal insulation via hole 13. On the basis of the first part, continue to etch the substrate 1 to form grooves.

Therefore, the combination of dry etching technology and wet etching technology can reduce the processing cost of the micro heater and ensure the molding quality. Moreover, when etching the heat-insulating through hole 13, first adopt dry etching and then wet etching, which can avoid possible damage to the supporting film 2 caused by dry etching; when etching the groove, use dry etching The technology combined with wet etching can increase the depth of the groove, and avoid the formation of a closed cavity in the above-mentioned cavity of the micro-heater after packaging.

Optionally, the above dry etching technique may be deep reactive ion etching.

Optionally, the etchant of the above wet etching technique may be a mixed solution of polyethylene glycol octylphenyl ether and tetramethylammonium hydroxide. For example, when the substrate 1 is a silicon substrate, the etchant of the wet etching technique uses the above-mentioned mixed solution, which can eliminate the acute-angle stress concentration structure caused by the anisotropy of silicon, and is beneficial to eliminate the formation of protrusions on the groove. corrosion problem.

In the description of this specification, references to the terms "one embodiment," "some embodiments," "exemplary embodiments," "example," "specific examples," or "some examples" are intended to mean that the implementation A specific feature, structure, material, or characteristic described by an embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications, substitutions and modifications can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the invention is defined by the claims and their equivalents.

Claims (13)

1. a kind of microheater, it is characterised in that including：

Substrate, the substrate has the first surface and second surface being oppositely arranged along its thickness direction, and the substrate is provided with Run through its heat-insulated through hole in thickness direction, and the heat-insulated through hole and extraneous ventilation device are communicated with the substrate；

Support membrane, the support membrane is located on the first surface of the substrate and covers the first end of the heat-insulated through hole；

Heating member, the heating member is located on the surface of the remote heat-insulated through hole of the support membrane；

Encapsulating shell, the encapsulating shell is located on the second surface of the substrate and covers the second end of the heat-insulated through hole.

2. microheater according to claim 1, it is characterised in that the second surface of the substrate is provided with recessed Groove, limits the ventilation device between the groove and the encapsulating shell.

3. microheater according to claim 2, it is characterised in that the groove is multiple and along the heat-insulated through hole Be provided at circumferentially spaced.

4. microheater according to claim 2, it is characterised in that the cross section of the groove is curved or U-shaped.

5. the microheater according to any one of claim 1-4, it is characterised in that the heat-insulated through hole is located at institute The end for stating first surface is formed as circular.

6. microheater according to claim 5, it is characterised in that the cross-sectional area of the heat-insulated through hole is by institute The side for stating first surface to the second surface is increased up.

7. the microheater according to any one of claim 1-4, it is characterised in that the heating member is adding thermal resistance Silk, the Curvature varying of the resistive heater in their extension direction is continuous.

8. microheater according to claim 7, it is characterised in that the resistive heater is on the support membrane Project the polygon of rounded, oval, involute shape or apex rounding.

9. microheater according to claim 7, it is characterised in that the resistive heater include it is parallel to each other and Every the multiple straight sections and the curved segment of the two neighboring straight section of connection of setting, the curved segment and the junction of the straight section are smooth Transition.

10. a kind of processing method of microheater according to any one of claim 2-9, it is characterised in that including Following steps：

S10, in the first surface of the substrate deposit to form the support membrane；

S20, the heating member is laid on the support membrane；

S30, from the second surface of the substrate along its thickness direction the substrate is etched to form the heat-insulated through hole, The substrate is etched on the second surface of the substrate to form the groove；

S40, use bonding agent to be connected the encapsulating shell with the substrate to encapsulate the internal components of the microheater.

11. the processing method of microheater according to claim 10, it is characterised in that in the S30 steps, is carved The step of losing the heat-insulated through hole and the groove is as follows：

Dry etching technology is first used to etch the substrate along its thickness direction to be formed by the second surface of the substrate The Part I of the heat-insulated through hole, is etched on the second surface of the substrate described using above-mentioned dry etching technology Substrate is to form the Part I of the groove；

Continued again using wet etching technique on the basis of the Part I of the heat-insulated through hole along the thickness side of the substrate To etching the substrate to form the heat-insulated through hole, using above-mentioned wet etching technique the Part I of the groove base Continue to etch the substrate to form the groove on plinth.

12. the processing method of microheater according to claim 11, it is characterised in that the dry etching technology is Deep reaction ion etching.

13. the processing method of microheater according to claim 11, it is characterised in that the wet etching technique Corrosive agent is the mixed solution of Triton X-100 and TMAH.