WO2018196089A1

WO2018196089A1 - Miniature heater and processing method therefor

Info

Publication number: WO2018196089A1
Application number: PCT/CN2017/086296
Authority: WO
Inventors: 罗彪
Original assignee: 广东美的制冷设备有限公司
Priority date: 2017-04-24
Filing date: 2017-05-27
Publication date: 2018-11-01

Abstract

Disclosed are a miniature heater and a processing method therefor, wherein the miniature heater comprises: a substrate (1), a supporting membrane (2), a heating member (3) and an enclosure, wherein the substrate (1) is provided with a first surface (11) and a second surface (12) which are arranged opposite each other in a thickness direction thereof; the substrate (1) is provided with a heat insulation through hole (13) penetrating same in the thickness direction; an aeration structure (14) connecting the heat insulation through hole (13) and the outside is arranged on the substrate (1); the supporting membrane (2) is arranged on the first surface (11) of the substrate (1) and covers a first end of the heat insulation through hole (13); the heating member (3) is arranged on a surface, away from the heat insulation through hole (13), of the supporting membrane (2); and the enclosure is arranged on the second surface (12) of the substrate (1) and covers a second end of the heat insulation through hole (13).

Description

Micro heater and processing method thereof

Technical field

The invention relates to the technical field of MEMS, and in particular to a micro heater and a processing method thereof.

Background technique

In the related art, the structure of the surface type micro-heater mainly has a closed film structure and a cantilever beam structure, and the power consumption of the cantilever beam structure is lower than that of the closed film structure, and the cantilever beam structure is caused by the thermal stress release problem of the composite film. The device undulates in the horizontal plane, and as the reaction temperature of the device increases, the composite film will be thermally expanded, which will increase the local accumulation of thermal stress in the cantilever beam structure. The mechanical properties of the closed film are better, the mechanical properties of the suspension film are worse, but the compatibility with the CMOS process is better. Most sensors use this design because of the better mechanical strength of the closure film and the subsequent coating of sensitive materials and subsequent sensor life.

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

Summary of the invention

The present application is based on the discovery and recognition of the following facts and problems by the inventors: the inventors discovered through research that the surface type micro-heater with a closed membrane structure is damaged by the internal device during long-term work. Caused by fatigue fracture. Through further research and exploration by the inventors, it is found that the cause of fatigue fracture of the device is that the gas pressure change in the cavity of the surface-type micro-heating of the closed film structure causes the support film to be affected by the thermal stress and the pressure difference. The periodic/long-term pressure difference caused, so that the support film is 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. To this end, the present invention proposes a micro-heater which is simple in structure, long in service life, and high in reliability.

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

A micro-heater according to an embodiment of the first aspect of the present invention, comprising: a substrate having a first surface and a second surface disposed opposite to each other in a thickness direction thereof, the substrate being provided with a thickness direction extending therethrough a heat insulating through hole, and the substrate is provided with a ventilation structure connecting the heat insulating through hole and the outside; a supporting film, the supporting film is disposed on the first surface of the substrate and is covered a first end of the heat insulating through hole; a heating member disposed on a surface of the supporting film away from the heat insulating through hole; a package shell, wherein the package shell is disposed on the substrate And sealing the second end of the heat insulating through hole on the second surface.

A micro-heater according to an embodiment of the present invention, by providing a ventilation structure that communicates a heat-insulating through hole and an outside on a substrate, thereby defining a cavity defined by the heat-insulating through hole, the support film, and the package case when the micro-heater operates The room is connected to the outside world. Prevents the problem of damage to the device due to the pressure difference existing inside and outside the chamber.

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

Optionally, the grooves are plural and disposed along a circumferential interval of the heat insulating through holes.

Optionally, the groove has a curved or U-shaped cross section.

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

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

Optionally, the heat insulating through hole is formed in a truncated cone shape.

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

Optionally, the projection of the heating resistance wire on the support film is a round, elliptical, involute or rounded polygon at the vertex.

Optionally, the heating resistor wire comprises a plurality of straight segments arranged parallel to each other and spaced apart, and a curved segment connecting adjacent two straight segments, the curved portion and the straight segment connecting smoothly.

A method of processing a micro-heater according to an embodiment of the second aspect of the present invention includes the steps of: S10, depositing the support film on the first surface of the substrate; S20, laying on the support film a heating member; S30, etching the substrate from the second surface of the substrate along a thickness direction thereof to form the heat insulating through hole, etching on the second surface of the substrate The substrate to form the recess; S40, connecting the package to the substrate with an adhesive to encapsulate an internal device of the micro-heater.

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

According to some optional embodiments of the present invention, in the step S30, the step of etching the insulating via and the recess is as follows: first using the dry etching technique by the first The two surfaces etch the substrate along a thickness direction thereof to form a first portion of the insulating via, and etching the substrate on the second surface of the substrate by the above dry etching technique Forming a first portion of the recess; further etching the substrate along a thickness direction of the substrate to form the thermal insulation on a first portion of the thermally insulated through hole by a wet etching technique The via hole continues to etch the substrate to form the recess on the basis of the first portion of the recess using the wet etching technique described above.

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

Optionally, the etchant of the wet etching technique is a mixture of polyethylene glycol octyl phenyl ether and tetramethyl ammonium hydroxide. Mix solution.

According to some optional embodiments of the present invention, the support film is a composite film structure composed of a silicon oxide layer and a silicon nitride layer, and in the step S10, depositing a formation on the first surface of the substrate The step of supporting the film is as follows: a silicon oxide layer is deposited on the first surface of the substrate by a low pressure chemical vapor deposition (LPCVD) method; and then a plasma enhanced chemical vapor deposition (PECVD) method is applied to the silicon oxide layer. A silicon nitride layer is deposited.

The additional aspects and advantages of the invention will be set forth in part in the description which follows.

DRAWINGS

The above and/or additional aspects and advantages of the present invention will become apparent and readily understood from

1 is a partial perspective structural view of a micro-heater according to an embodiment of the present invention;

2 is a partial perspective structural view of another angle of a micro-heater according to an embodiment of the present invention.

Reference mark:

Substrate 1, first surface 11, second surface 12, thermal insulation through hole 13, first segment 131, second segment 132, aeration structure 14,

Support film 2,

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

Electrode 4.

detailed description

The embodiments of the present invention are described in detail below, and the examples of the embodiments are illustrated in the drawings, wherein the same or similar reference numerals are used to refer to the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are intended to be illustrative of the invention and are not to be construed as limiting.

In the description of the present invention, it is to be understood that the terms "center", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", The orientation or positional relationship of "horizontal", "top", "bottom", "inside", "outer", "axial", "radial", "circumferential", etc. is based on the orientation or position shown in the drawings. The present invention is to be construed as being limited to the invention and is not intended to limit the scope of the invention. Furthermore, features defining "first" and "second" may include one or more of the features, either explicitly or implicitly. In the description of the present invention, "a plurality" means two or more unless otherwise stated.

In the description of the present invention, it should be noted that the terms "installation", "connected", and "connected" are to be understood broadly, and may be fixed or detachable, for example, unless otherwise explicitly defined and defined. Connected, or integrally connected; can be mechanical or electrical; can be directly connected, or indirectly connected through an intermediate medium, can be the internal communication of the two components. The specific meaning of the above terms in the present invention can be understood in a specific case by those skilled in the art.

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

As shown in FIGS. 1 and 2, a micro-heater according to an embodiment of the first aspect of the present invention includes a substrate 1, a support film 2, a heating member 3, and a package case (not shown). For example, the above micro heater may be a face type micro heater, and the above micro heater may be applied to the field of sensors.

Specifically, the substrate 1 has a first surface 11 and a second surface 12 which are disposed opposite each other in the thickness direction thereof, and when the substrate 1 is placed in the horizontal direction, the first surface 11 and the second surface 12 are on the substrate 1 Surface and lower surface. The substrate 1 is provided with a heat insulating through hole 13 penetrating therethrough in the thickness direction, and the substrate 1 is provided with a ventilation structure 14 that communicates the heat insulating through hole 13 and the outside. Alternatively, the substrate 1 may be a silicon substrate.

The support film 2 is disposed on the first surface 11 of the substrate 1 and covers the first end of the heat insulating through hole 13. The middle portion of the support film 2 covers the first end of the heat insulating through hole 13, and the support film 2 is adjacent thereto. A portion of the peripheral edge is supported on the substrate 1 and connected to the substrate 1. The support film 2 may be a silicon oxide film, a silicon nitride film, or a silicon oxide/silicon nitride composite film.

The heating member 3 is provided on a surface of the support film 2 away from the heat insulating through hole 13, and the heating member 3 is supported by the support film 2 and the heating member 3 is spaced apart from the heat insulating through hole 13. Alternatively, the heating member 3 may be in the form of a filament, a sheet or the like. The substrate 1 is further provided with an electrode 4 connected to the heating member 3, and the electrode 4 can be disposed adjacent to the outer periphery of the substrate 1. For example, when the substrate 1 is square, the electrodes 4 may be provided at the four corners of the substrate 1.

The package is disposed on the second surface 12 of the substrate 1 and covers the second end of the heat insulating through hole 13. The second end and the first end of the heat insulating through hole 13 are respectively covered by the package shell and the support film 2, The package, the support film 2 and the heat insulating through hole 13 are mutually defined to define a chamber.

It can be understood that during the operation of the micro heater, the heating member 3 works to generate heat, and the supporting film 2 separates the heating member 3 from the heat insulating through hole 13, and at this time, the two surfaces of the supporting film 2 are different. The pressure, one of the two surfaces of the support film 2 faces the heating member 3 and the other surface faces the chamber, so that the support film 2 is subjected to a heat-induced pressure difference in addition to its own thermal stress.

By providing the above-mentioned ventilation structure 14 on the substrate 1, the chamber can be communicated with the outside through the ventilation structure 14, whereby the gas pressure in the chamber and the gas pressure outside thereof can be reduced when the micro heater is operated. The pressure difference causes the gas pressure in the chamber to converge with the pressure of the gas outside thereof, so that the pressure difference of the support film 2 can be reduced, so that the pressure on both sides of the support film 2 tends to be uniform, thereby preventing the support film. 2 The fatigue damage caused by the periodic/long-term pressure difference prolongs the service life of the micro heater. Improve the reliability of micro heater operation.

The micro-heater according to the embodiment of the present invention is provided with a ventilation structure 14 that communicates the heat-insulating through-hole 13 and the outside on the substrate 1, whereby the micro-heater operates, the heat-insulating through-hole 13, the support film 2, and The chamber defined by the encapsulating case communicates with the outside to prevent the device from being easily damaged due to a pressure difference existing inside and outside the chamber.

According to some alternative embodiments of the present invention, referring to FIG. 2, the second surface 12 of the substrate 1 is provided with a groove which is extendable in the radial direction and penetrates the inner wall of the heat insulating through hole 13 and the substrate 1. The peripheral wall defines a venting structure 14 between the recess and the encapsulating shell. Thus, by providing a groove on the second surface 12 of the substrate 1, the forming of the venting structure 14 can be facilitated and the venting structure 14 can be made simple.

Alternatively, referring to FIG. 2, the grooves may be plural and disposed along the circumferential interval of the heat insulating through holes 13. Thereby, the gas in the chamber and the gas outside it can be quickly and uniformly circulated, so that the gas pressure in the chamber tends to be more uniform with the pressure of the outside air, and the gas pressure of each part in the chamber can be made. More even. For example, the plurality of grooves may be arranged in a radial shape, thereby shortening the flow path of the gas and increasing the flow area of the gas, so that the pressure on both sides of the support film 2 tends to be uniform, which is more remarkable. The pressure difference experienced by the support film 2 is reduced.

Alternatively, the cross section of the groove may be curved or U-shaped. Thereby, the structure of the groove is simple and easy to be formed, and the inner wall surface of the groove is smoothed to avoid the generation of stress, thereby further improving the reliability of the micro heater.

According to some alternative embodiments of the present invention, referring to Figures 1 and 2, the end of the insulating through-hole 13 at the first surface 11 is formed in a circular shape such that the cover of the support film 2 insulates the portion of the through-hole 13 It is also circular, that is, the portion of the support film 2 that is suspended is circular, so that the portion of the support film 2 that is in a suspended state is smooth and continuous, and the appearance of the lobes is avoided, so that the support film 2 can be prevented. The stress concentration problem further improves the life of the support film 2 and the reliability of the operation of the micro heater. Alternatively, the support film 2 as a whole may have a circular shape or a square shape.

Further, the cross-sectional area of the heat insulating through hole 13 is increased in the direction from the first surface 11 to the second surface 12 (refer to the upward and downward directions in FIG. 2). Thereby, the overall structural stability and strength of the micro-heater can be improved, and the chip density of the micro-heater can be increased.

For example, the heat insulating through holes 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 having different inner diameters, and the first segment 131 and the second segment 132 are each formed into a cylindrical shape, wherein the first segment 131 is adjacent to the partition. The first surface 11 of the thermal via 13 and the second segment 132 are adjacent to the second surface 12 of the insulating 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 alternative embodiments of the present invention, referring to Fig. 1, the heating member 3 may be a heating resistance wire whose curvature change in the direction in which the resistance wire extends is continuous. Thereby, between the various parts of the heating resistor wire The smooth connection transition can prevent the problem of structural stress concentration on the heating member 3, further improving the reliability of the micro heater.

For example, the projection of the heating resistor wire on the support film 2 may be a circular, elliptical, involute or rounded polygon at the apex.

For another example, referring to FIG. 1, the heating resistor wire may include a plurality of straight segments 31 arranged parallel to each other and spaced apart, and a curved segment 32 connecting adjacent two straight segments 31, the smooth transition of the junction of the curved segments 32 and the straight segments 31. Thereby, the heating resistor wire can be evenly distributed on the support film 2, so that the micro-heater can obtain a large-area and high-quality uniform temperature region during operation.

A method of processing a micro-heater according to an embodiment of the second aspect of the present invention will now be described with reference to FIGS. 1 and 2.

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

S10, depositing a support film 2 on the first surface 11 of the substrate 1. The support film 2 described above may be deposited on the first surface 11 of the substrate 1 by chemical vapor deposition techniques, and the support film 2 may 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 using a low pressure chemical vapor deposition technique or a plasma enhanced chemical vapor deposition technique. Wherein, before the support film 2 is deposited on the substrate 1, the first surface 11 and the second surface 12 of the substrate 1 may be polished, whereby the connection strength and reliability between the support film 2 and the substrate 1 can be enhanced. .

Optionally, the support film 2 is a composite film structure composed of a silicon oxide layer and a silicon nitride layer. In the step S10, the step of depositing the support film 2 on the first surface 11 of the substrate 1 is as follows: Depositing a silicon oxide layer on the first surface 11 of the substrate 1 by a low pressure chemical vapor deposition (LPCVD) method; then depositing a silicon nitride layer on the silicon oxide layer by plasma enhanced chemical vapor deposition (PECVD) A low stress composite film structure is formed.

S20, the heating member 3 is disposed on the support film 2, and the heating member 3 may be deposited on the support film 2 by a sputtering process. For example, a magnetron sputtering method may be employed. The heating element 3 is sputter-deposited on the support film 2 according to design requirements, and the heating element 3 may have a circular shape, an elliptical shape, an involute shape, a rounded polygon at the vertex or a serpentine shape. .

S30, etching the substrate 1 from the second surface 12 of the substrate 1 in a thickness direction thereof (refer to a downward-upward direction in FIG. 2) to form a heat-insulating through hole 13 on the second surface 12 of the substrate 1. The substrate 1 is etched to form a groove. The etching of the insulating via 13 and the recess may be performed simultaneously or sequentially (for example, the insulating via 13 may be etched first, and then the recess may be etched). Of course, simultaneous etching of the insulating via 13 and the recess can improve processing efficiency.

S40. Attaching the package to the substrate 1 with an adhesive to encapsulate the internal components of the micro-heater. At the time of encapsulation, an adhesive is applied to the package, and the package is bonded to the second surface 12 of the substrate 1. When the adhesive is applied on the package shell, the thickness of the adhesive on the bonding area on the package can be uniform and smaller than the depth of the groove to prevent When the encapsulating case is bonded to the substrate 1, the groove is filled with the adhesive so that the venting structure 14 of the micro-heater is blocked.

According to some optional embodiments of the present invention, in the step S30, the steps of etching the heat insulating through holes 13 and the grooves are as follows:

First, the substrate 1 is etched from the second surface 12 of the substrate 1 in the thickness direction thereof by a dry etching technique to form a first portion of the insulating via 13 by using the above dry etching technique in the second of the substrate 1. The substrate 1 is etched on the surface 12 to form a first portion of the recess.

Further, the wet etching technique is used to continue etching the substrate 1 along the thickness direction of the substrate 1 to form the heat insulating through holes 13 on the basis of the first portion of the heat insulating through holes 13, and the wet etching technique is used in the grooves. The substrate 1 continues to be etched based on the first portion to form a recess.

Thus, the combination of the dry etching technique and the wet etching technique can reduce the processing cost of the micro heater and ensure the molding quality. Moreover, the dry etching is performed by dry etching and then wet etching, thereby avoiding possible damage of the support film 2 by dry etching; dry etching is used when etching the groove The technique combined with wet etching can increase the depth of the groove and prevent the above-mentioned chamber of the micro-heater after packaging from forming a closed cavity.

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

Alternatively, the etchant of the above wet etching technique may be a mixed solution of polyethylene glycol octyl phenyl ether and tetramethylammonium hydroxide. For example, when the substrate 1 is a silicon substrate, the etching agent of the wet etching technique adopts the above mixed solution, which can eliminate the acute-angle stress concentration structure generated by the silicon anisotropy, and is advantageous for eliminating the formation of the boss on the groove. Corrosion problem.

In the description of the present specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiment", "example", "specific example", or "some examples", etc. Particular features, structures, materials or features described in the examples or examples are included in at least one embodiment or example of the invention. In the present specification, the schematic representation of the above terms does not necessarily mean the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples.

While the embodiments of the present invention have been shown and described, the embodiments of the invention may The scope of the invention is defined by the claims and their equivalents.

Claims

A miniature heater characterized by comprising:

a substrate having a first surface and a second surface disposed opposite to each other in a thickness direction thereof, the substrate being provided with a heat insulating through hole penetrating therethrough in a thickness direction, and having a communication on the substrate The heat insulating through hole and the external ventilation structure;

a support film, the support film is disposed on the first surface of the substrate and capping the first end of the heat insulating through hole;

a heating member, the heating member is disposed on a surface of the support film away from the heat insulating through hole;

An encapsulating shell disposed on the second surface of the substrate and covering a second end of the insulating through hole.
The micro-heater according to claim 1, wherein said second surface of said substrate is provided with a groove, and said venting structure is defined between said groove and said encapsulating case.
The micro-heater according to claim 2, wherein the plurality of grooves are plural and disposed along a circumferential interval of the heat insulating through holes.
A micro-heater according to claim 2 or 3, wherein the groove has a curved or U-shaped cross section.
The micro-heater according to any one of claims 1 to 4, wherein an end of the heat-insulating through hole at the first surface is formed in a circular shape.
The micro-heater according to claim 5, wherein a cross-sectional area of the heat insulating through hole increases in a direction from the first surface to the second surface.
The micro-heater according to claim 6, wherein the heat insulating through hole is formed in a truncated cone shape.
The micro-heater according to any one of claims 1 to 7, wherein the heating member is a heating resistance wire, and the change in curvature of the heating resistance wire in the extending direction thereof is continuous.
The micro-heater according to claim 8, wherein the projection of the heating resistance wire on the support film is a round, elliptical, involute or rounded polygon at a vertex.
The micro-heater according to claim 8, wherein said heating resistor wire comprises a plurality of straight segments arranged parallel to each other and spaced apart, and a bent segment connecting adjacent two of said straight segments, said bent segments and The connection of the straight segments is smoothly transitioned.
A method of processing a micro-heater according to any one of claims 2 to 10, comprising the steps of:

S10, depositing the support film on the first surface of the substrate;

S20, laying the heating member on the support film;

S30. etching the substrate from the second surface of the substrate along a thickness direction thereof to form the heat insulating through hole, and etching the substrate on the second surface of the substrate Forming the groove;

S40. Attaching the package shell to the substrate with an adhesive to encapsulate an internal device of the micro heater.
The method of processing a micro-heater according to claim 11, wherein in the step S30, the step of etching the heat-insulating through hole and the groove is as follows:

First etching the substrate from the second surface of the substrate along a thickness direction thereof by a dry etching technique to form a first portion of the insulating via, using the dry etching technique described above Etching the substrate on the second surface of the substrate to form a first portion of the recess;

And further etching the substrate along the thickness direction of the substrate to form the heat insulating through hole by using a wet etching technique on the first portion of the heat insulating through hole, using the above wet etching Technique continues to etch the substrate to form the recess based on the first portion of the recess.
The method of processing a micro-heater according to claim 12, wherein the dry etching technique is deep reactive ion etching.
The method of processing a micro-heater according to claim 12 or 13, wherein the etching agent of the wet etching technique is a mixed solution of polyethylene glycol octylphenyl ether and tetramethylammonium hydroxide.
The method of processing a micro-heater according to any one of claims 11 to 14, wherein the support film is a composite film structure composed of a silicon oxide layer and a silicon nitride layer, in the step S10 The step of depositing the support film on the first surface of the substrate is as follows:

First depositing a silicon oxide layer on the first surface of the substrate by low pressure chemical vapor deposition (LPCVD);

A silicon nitride layer is then deposited on the silicon oxide layer by plasma enhanced chemical vapor deposition (PECVD).