CN115215283A

CN115215283A - Thin film getter structure with micro heater and manufacturing method thereof

Info

Publication number: CN115215283A
Application number: CN202110414598.9A
Authority: CN
Inventors: 王诗男; 鲁涛
Original assignee: Shanghai Jingwei Material Technology Co ltd; Shanghai Industrial Utechnology Research Institute
Current assignee: Shanghai Jingwei Material Technology Co ltd; Shanghai Industrial Utechnology Research Institute
Priority date: 2021-04-16
Filing date: 2021-04-16
Publication date: 2022-10-21

Abstract

The present application provides a thin-film getter structure having a microheater and a method of making the same, the thin-film getter structure comprising: a substrate; a heater formed on one main surface side of the substrate; and a getter film formed on a surface of the heater, wherein the heater includes: a first insulating film; a thin film resistor formed on an upper surface of the first insulating film; and a second insulating film covering the thin film resistor, wherein two ends of the thin film resistor are electrodes exposed from the second insulating film, the main surface of the substrate is provided with a cavity, the part of the thermion bearing the getter film is positioned above the cavity, and the part of the thermion bearing the getter film is supported on the main surface around the cavity through a connecting part.

Description

Thin film getter structure with micro heater and manufacturing method thereof

Technical Field

The present application relates to the field of semiconductor technology, and more particularly, to a thin film getter structure having a micro-heater and a method for manufacturing the same.

Background

Some semiconductor devices, particularly Micro Electro Mechanical Systems (MEMS) devices, require packaging in a vacuum environment. For example, MEMS acceleration sensors, gyroscopes, and vacuum gauges with high-speed vibrating components require that the vibrating parts be enclosed in a relatively stable vacuum. For another example, a MEMS pressure sensor requiring a vacuum chamber also requires a higher vacuum in the vacuum chamber, and the vacuum level remains stable. Some infrared sensors also require the device to be enclosed in a relatively high vacuum chamber.

On the one hand, achieving higher vacuum packaging is inherently challenging. Because, during the encapsulation process, there is often some residual gas trapped in the vacuum chamber. Therefore, it is often necessary to seal a getter in a vacuum chamber, activate the getter during the packaging process, or activate the getter after the packaging process is completed, so as to absorb the residual gas in the vacuum chamber, thereby achieving a high vacuum required for the device operation. Getters (getters), also known as getters, in the field of vacuum technology refer to materials that are capable of efficiently adsorbing and immobilizing certain or certain gas molecules. The getter material is generally a porous structure, when the active gas molecules collide with the clean getter material surface, some gas molecules are adsorbed, which is the physical adsorption of the getter material; some gas molecules will react chemically with the getter material to form a stable solid solution, which is chemisorption of the getter material. And gas molecules are continuously diffused into the material, so that the aim of pumping out a large amount of active gas is fulfilled. Activating the getter often requires several hundred degrees of high temperature warming of the getter. If the entire packaged device is heated from the outside, it is necessary that both the MEMS device itself and the packaging method and materials must be able to withstand such high temperatures, and there are significant limitations. In order to solve this problem, there is a technique in which a getter is coated on a resistance wire, both ends of the resistance wire are connected to conductive terminals of a package case, and the getter is heated by applying power to the resistance wire after the package, thereby activating the getter.

It should be noted that the above background description is only for the convenience of clear and complete description of the technical solutions of the present application and for the understanding of those skilled in the art. Such solutions are not considered to be known to the person skilled in the art merely because they have been set forth in the background section of the present application.

Disclosure of Invention

The inventor believes that the application of the activator on the resistance wire in the existing getter structure with the heater is large in size, is not suitable for a scene with a compact packaging space and is not suitable for mass production.

The embodiment of the application provides a film getter structure with a micro heater and a manufacturing method thereof, in the film getter structure, a getter film is arranged on the surface of a heater, the heater is of a laminated film structure, and the thickness of a film resistor of the heater is smaller, so that the thickness of the film getter structure can be reduced, the miniaturization of the film getter structure is facilitated, and the suspended structure of the heater can prevent heat loss and improve the heating efficiency of the getter film.

According to an aspect of an embodiment of the present application, there is provided a thin film getter structure having a micro-heater, comprising:

a substrate;

a heater formed on one main surface side of the substrate; and

a getter film formed on the surface of the heater,

wherein the heater comprises:

a first insulating film;

a thin film resistor formed on an upper surface of the first insulating film; and

a second insulating film covering the thin film resistor,

both ends of the thin film resistor are electrodes exposed from the second insulating film,

wherein the one main surface of the substrate has a cavity,

the part of the heater carrying the getter film is located above the hollow,

the portion of the heater carrying the getter film is supported on the one main surface around the cavity by a connecting portion.

According to another aspect of the embodiments of the present application, there is provided a vacuum packaging structure of a mems device, including:

the vacuum packaging device comprises a vacuum packaging shell, a vacuum cavity and a vacuum pump, wherein the vacuum packaging shell is internally formed into the vacuum cavity;

the micro-electro-mechanical system device is packaged in the vacuum packaging shell;

the conductive terminal is arranged inside the vacuum packaging shell at one end, and the other end of the conductive terminal is arranged outside the vacuum packaging shell; and

the thin-film getter structure of the foregoing aspect of the embodiments, being enclosed inside the vacuum-sealed enclosure,

wherein an electrode of the thin-film resistor of the thin-film getter structure is in electrical communication with the conductive terminal.

According to yet another aspect of embodiments of the present application, there is provided a method of making a thin film getter structure having a micro-heater, comprising:

forming a heater on one main surface of a substrate;

etching the heater to form a connecting part and a pattern of a part of the heater, which is used for bearing the getter film, and corroding the main surface of the substrate to suspend the part of the heater, which is used for bearing the getter film; and

forming a getter film on the surface of the heater;

wherein the step of forming the thermions comprises:

forming a first insulating film on one main surface of the substrate;

forming a thin film resistor on the upper surface of the first insulating film; and

forming a second insulating film covering the thin film resistor,

wherein both ends of the thin film resistor are formed as electrodes exposed from the second insulating film.

The beneficial effect of this application lies in: in the thin film getter structure, the getter thin film is arranged on the surface of the heater, the heater is a laminated thin film structure, and the thin film resistance thickness of the heater is small, so that the thickness of the thin film getter structure can be reduced, the miniaturization of the thin film getter structure is facilitated, the suspended structure of the heater can prevent heat loss, and the heating efficiency of the getter thin film is improved.

Specific embodiments of the present application are disclosed in detail with reference to the following description and drawings, indicating the manner in which the principles of the application may be employed. It should be understood that the embodiments of the present application are not so limited in scope. The embodiments of the application include many variations, modifications and equivalents within the spirit and scope of the appended claims.

Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments, in combination with or instead of the features of the other embodiments.

It should be emphasized that the term "comprises/comprising" when used herein, is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps or components.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the application, are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. It is obvious that the drawings in the following description are only some embodiments of the application, and that for a person skilled in the art, other drawings can be derived from them without inventive effort. In the drawings:

FIG. 1 is another schematic view of a getter structure provided herein;

FIG. 2 is another schematic view of a getter structure provided herein;

FIG. 3 is another schematic view of a process for making a getter structure provided herein;

fig. 4 is a schematic view of a method of applying the getter structure provided herein.

Detailed Description

The foregoing and other features of the present application will become apparent from the following description, taken in conjunction with the accompanying drawings. In the description and drawings, particular embodiments of the application are disclosed in detail as being indicative of some of the embodiments in which the principles of the application may be employed, it being understood that the application is not limited to the embodiments described, but, on the contrary, is intended to cover all modifications, variations, and equivalents falling within the scope of the appended claims.

In the description of the following examples of the present application: area refers to the area of the film in the "lateral direction", where "lateral" refers to the direction parallel to the substrate surface; "longitudinal" means a direction perpendicular to the substrate surface; in the "longitudinal direction", a direction pointing from the substrate toward the thermions is an "up" direction, a direction opposite to the "up" direction is a "down" direction, a surface of each layer structure along the "up" direction is an "upper surface", and a surface of each layer structure opposite to the "upper surface" is a "lower surface". The above directions are set for convenience of description of the technical solution of the present application, and do not represent the orientation of the thin film getter structure or the vacuum package structure during processing and use.

Example 1

Example 1 of the present application provides another getter structure. Such getter structures are self-heating. Fig. 1 is a schematic diagram of the present embodiment. In the present embodiment, in order to highlight the main idea of the present application, the schematic diagram of fig. 1 includes only the most basic elements. A) of fig. 1 is a plan view of the getter structure 100, b) of fig. 1 is a cross-sectional view of the getter structure 100 cut along the line designated AA' in a) of fig. 1, and c) of fig. 1 is a plan view of the sheet resistance 3 of the getter structure 100.

As shown in a) of fig. 1 and b) of fig. 1, the getter structure 100 comprises: a substrate 1, a heater 10 formed on the main surface 1a of the substrate 1, and a getter film 5 formed on the heater 10. The heater 10 includes a first insulating film 2 formed on the main surface 1a of the substrate 1, a conductive thin film resistor 3 formed on the first insulating film 2, and a second insulating film 4 formed on the thin film resistor 3. Wherein the second insulating film 4 has a better heat conductivity than the first insulating film 2. And, the area of the getter film 5 is smaller than that of the second insulating film 4 a. The overall area of the getter structure 100 is designed according to the gettering requirements. For example, the surface of getter structure 100 is a square as shown in fig. 1a, with one side having a length in the range of about 0.5-5 mm.

In this embodiment 1, the substrate 1 below the heater 10 has the cavity 6. That is, the main portion of the heater 10 (i.e., the portion on which the getter film 5 is mounted) is suspended above the cavity 6 and supported by the main surface of the substrate 1 around the cavity 6 through the connection portion. Wherein the connecting portion is, for example, a cantilever beam 7 (e.g., comprising 7a,7b,7c, 7d), and the cantilever beam 7 may be connected to the main face 1a of the substrate 1. The cantilever beam 7 may have two or more branches. For example, in this embodiment, the cantilever 7 comprises four

branches

7a,7b,7c,7 d. In this configuration, the bulk of the heater 10 and the getter film 5 are separated from the remaining regions and connected only by the cantilever beam 7. Thus, the heat generated by energizing the thin film resistor 3 is only lost in terms of solid conduction through the cantilever 7. The width, length and thickness of the cantilever beam are designed appropriately so that the solid conduction heat loss generated by the cantilever beam 7 becomes sufficiently small. As a result, compared with the case where the heater is in contact with the main surface 1a of the substrate 1, the getter structure 100 of the present embodiment conducts the heat generated by the heater to the upper surface of the getter film 5 more intensively, thereby improving the heating efficiency required for activating the getter film 5, and being effective in saving the heating energy and increasing the maximum heatable temperature.

The substrate 1 has two corresponding main faces, namely a first main face 1a and a second main face 1b. The substrate 1 may be a wafer commonly used in the field of semiconductor manufacturing, such as a Silicon wafer, a Silicon On Insulator (SOI) wafer, a Silicon germanium wafer, a gallium nitride wafer, or a SiC wafer, or may be an insulating wafer such as quartz, sapphire, or glass. The substrate 1 may be a wafer commonly used in the field of semiconductor manufacturing, and the surface of the wafer may further include various films and various structures required for semiconductor devices and MEMS devices. The present embodiment does not limit this. In a particular example, the substrate 1 is a silicon substrate, with a thickness of about 700 microns and a diameter of about 200mm. Although the present application has been described with reference to the substrate 1 being a semiconductor substrate, the present application is not limited thereto, and the substrate 1 may be replaced with a non-semiconductor substrate.

The material and thickness of the first insulating film 2 formed on the main surface 1a of the substrate 1 are designed according to the thermionic performance requirements. Its main effects are two. One is to realize electrical insulation between the conductive thin film resistor 3 and the substrate 1. And secondly, the thermal insulation between the thin film resistor 3 and the substrate 1 is realized, so that the heat generated after the thin film resistor 3 is electrified flows towards the getter film 5 effectively. For example, if the thermal insulation of the substrate 1 is not sufficient, the thermal insulation of the first insulating film 2 may be sufficiently higher than the thermal insulation of the substrate 1. The first insulating film 2 may be a film made of a single material, a composite film made of a plurality of materials, or a composite film formed by laminating a plurality of films made of a single material. For example, the first insulating film 2 is a single film made of silicon oxide. The thickness of the first insulating film 2 is, for example, 0.1 to 2 μm.

The thin film resistor 3 formed on the first insulating film 2 can be designed according to the requirement of activating the getter film 5. The function of the thin film resistor 3 is to generate a sufficiently high temperature after the current is applied to activate the getter film 5. Therefore, the material, shape, etc. of the thin film resistor 3 can be designed according to the requirement of the getter activating film 5. The material of the thin-film resistor 3 must be able to withstand the temperatures required to activate the getter film 5, and its resistance must be of a size suitable to produce, after suitable energization, a sufficiently high temperature to activate the getter film 5. The material of the thin-film resistor 3 may be metal. For example, the material of the thin film resistor 3 is a metal containing one or two or more of Pt, W, au, al, cu, ni, ta, ti, and Cr. The material of the thin-film resistor 3 may be a semiconductor. For example, the material of the thin film resistor 3 is polysilicon. When the material of the thin film resistor 3 is polysilicon, the polysilicon can be doped as required to adjust the conductivity thereof. The material sheet of the thin-film resistor 3 may be a metal compound. For example, the material of the thin film resistor 3 is TiN or TaAlN. The thickness of the thin film resistor 3 is, for example, 0.1 to 1 μm. The thin film resistor 3 may be a continuous thin film or a patterned thin film as shown in fig. 1 a), b, and c.

For example, the sheet resistor 3 is a single-fold line-shaped film as shown in the plan view of c) of fig. 1. One end of the thin film resistor 3 is connected with the electrode 3a through the cantilever beam 7a, and the other end of the thin film resistor 3 is connected with the electrode 3b through the cantilever beam 7 b. The

electrodes

3a and 3b of the thin-film resistor 3 are exposed through a window 4d formed in the second insulating film 4 so as to be connected to an external power supply (not shown).

The second insulating film 4 is formed on the thin film resistor 3, and its material and thickness are designed according to the thermionic performance requirements. It has three main functions. One is to achieve electrical isolation between the conductive thin-film resistor 3 and the getter film 5. Secondly, the heat generated by the thin film resistor 3 is collected and conducted to the getter film 5, so that the temperature of the getter film 5 reaches the activation temperature. Thirdly, the heat generated by the thin film resistor 3 is uniformly conducted to the getter film 5. The second insulating film 4 has a better heat conductivity than the first insulating film 2, which facilitates the effective conduction of the heat generated by the thin film resistor 3 after being energized to the getter film 5. The second insulating film 4 may be a film made of a single material, a composite film made of a plurality of materials, or a composite film formed by laminating a plurality of films made of a single material. For example, the first insulating film 2 is a single film made of silicon oxide, and the second insulating film 4 is a single film made of silicon nitride. At this time, the long film conditions of the first insulating film 2 and the second insulating film 4 are adjusted so that the second insulating film 4 has a higher thermal conductivity than the first insulating film 2. The thickness of the second insulating film 4 is, for example, 0.1 to 2 μm. The second insulating film 4a covering the major portion of the conductive thin film resistor 3 is separated from the second insulating film 4b of the remaining region by the isolation groove 4c, so that the heat generated from the thin film resistor 3 is efficiently conducted to the getter film 5. The isolation groove 4c is a channel formed on the second insulating film 4, penetrating the upper and lower surfaces of the second insulating film 4 to reach the surface of the underlying first insulating film 2. The isolation groove 4c is formed in the periphery of the thin film resistor 3.

The first insulating film 2, the thin film resistor 3 formed on the first insulating film 2, and the second insulating film 4 formed on the thin film resistor 3 constitute a heater 10.

The getter film 5 formed on the heater 10 is made of a getter material. The material, area and thickness of the getter film 5 are designed according to the type and quantity of the gas to be adsorbed. The area of the getter film 5 is smaller than that of the second insulating film 4a so that the getter film 5 can be effectively activated through the second insulating film 4 a. For example, the getter film 5 can be a Zr-based non-evaporable getter including ZrVFe, zrAl, zrC, and the like. The getter film 5 can be a Ti-based non-evaporable getter including materials such as Ti — Mo. The size, the ratio, and the like of the pores of the getter film 5 can be appropriately adjusted. For example, the pore ratio of the getter film 5 is 40% or more. The thickness of the getter film 5 is, for example, about 0.1 to 5 μm.

The getter structure 100, as described above, allows the getter film 5 to reach a maximum temperature during activation comprised between 200 ℃ and 1000 ℃. The overall design of the getter structure 100, and in particular the design of the thermionic device 10, can be optimized according to the actual desired activation temperature. For example, the film structure formed by the heater 10 and the getter film 5 needs to be designed with proper consideration of the overall stress, so that the getter structure 100, especially the cantilever beam 7, will not be damaged by the stress during the manufacturing and using processes. The cantilever beam 7 also has sufficient strength to support the membrane structure formed by the heater 10 and the getter membrane 5 in good suspension.

As described above, the present embodiment provides a thin film getter structure with a small volume and a self-contained heater, which can reduce the occupation of the volume of the tiny vacuum chamber. The structure can be processed by a semiconductor process, and has better mass production; in addition, the film getter structure of the embodiment can activate the film getter at any time as required due to the self-contained heater, so that gas which is increased along with time in the vacuum cavity is effectively adsorbed, and the service life of the MEMS device sealed in the vacuum cavity together is prolonged; moreover, in the structure of embodiment 1, the main portion of the heater 10 and the getter film 5 are connected to the remaining region only by the cantilever beam 7, so that the loss of heat generated by the energization of the thin film resistor 3 due to solid conduction becomes sufficiently small, and as a result, the getter structure of this embodiment can conduct the heat generated by the heater to the getter film more intensively, thereby increasing the heating efficiency required for activating the getter film, and having effects of saving heating energy and increasing the highest heating temperature.

Example 2

Example 4 of the present application provides another getter structure. This getter structure is self-contained with the MEMS heater. Fig. 2 is a schematic plan view of the present embodiment. In the present embodiment, in order to highlight the main idea of the present application, the schematic diagram of fig. 2 includes only the most basic elements. In this embodiment 2, similar to the above embodiment 1, reference is made to embodiment 1, and a detailed description thereof will be omitted.

In example 1, the getter structure 100 has two or more getter structure units composed of the heater 10 and the getter film 5 formed thereon. For example, as shown in fig. 2, the getter structure 100 has two getter structure units. Each getter structure unit has a similar structure to the getter structure 100 of example 1. The getter film 5-1 of the first getter structural unit corresponds to one heater 10-1 and the getter film 5-2 of the second getter structural unit corresponds to the other heater 10-2. The thermite 10-1 and the thermite 10-2 may be completely independent. However, in order to save the power input terminal, the heater 10-1 and the heater 10-2 may share one electrode 3c. Such a structure allows the thermionic valve 10-1 to be independently energized through the electrode 3-1a and the electrode 3c, and the thermionic valve 10-2 to be independently energized through the electrode 3-2a and the electrode 3c. That is, the getter film 5-1 and the getter film 5-2 may be separately activated by heating independently.

In addition to the effects of embodiment 1, the getter structure of this embodiment can also activate the independent thin film getters respectively at different time points more effectively, and prolong the service life of the MEMS devices sealed together in the vacuum chamber.

Example 3

Example 3 of the present application provides another method of making a getter structure. Fig. 3 is a schematic sectional view of the present embodiment. The getter structure 100 of embodiment 1 depicted in fig. 1 and embodiment 2 depicted in fig. 2 can be fabricated using the fabrication method of this embodiment. In the present embodiment, in order to highlight the main idea of the present application, the schematic diagram of fig. 3 includes only the most basic elements. The structure, material, and the like in embodiment 3 are the same as those in embodiments 1 and 2, and reference is made to embodiments 1 and 2, and detailed description thereof is omitted. For the sake of simplicity, this embodiment 3 will describe the manufacturing method by taking the getter structure 100 of embodiment 1 as an example.

The manufacturing method of the getter structure 100 provided in this embodiment 3 includes: a heater 10 is formed on one main surface 1a of a substrate 1, and a getter film 5 is formed on the heater 10. Further, the manufacturing method includes: before the getter film 5 is formed on the surface of the heater, the heater 10 is etched to form a pattern of a connection portion and a portion of the heater for supporting the getter film 5, and the main surface 1a of the substrate 1 is etched to suspend the portion of the heater 10 for supporting the getter film 5, for example: the heater 10 and the substrate 1 are processed so that a cavity is formed below the heater 10, and the substrate 1 is connected to the cantilever 7 (including 7a,7b,7c, and 7 d). The present manufacturing method will be described step by step below.

First, as shown in a) of fig. 3, the substrate 1 is prepared. In the present embodiment, the substrate 1 has two corresponding main surfaces, i.e., a first main surface 1a and a second main surface 1b. The substrate 1 is the substrate 1 described in example 2. For simplicity and convenience, the present embodiment will be described by taking the substrate 1 as an example of a Si substrate conventionally used in a semiconductor process.

Then, as shown in b) of fig. 3, the first insulating film 2 is formed on the one principal surface 1a of the substrate 1. The first insulating film 2 is the first insulating film 2 described in embodiment 2. For example, the first insulating film 2 is a silicon oxide film having a thickness of 0.4 μm, and is formed by conventional TEOS CVD (TEOS: CVD: chemical Vapor Deposition, chinese: chemical Vapor Deposition) and a supporting process.

Then, as shown in c) of fig. 3, the conductive thin film resistor 3 is formed on the first insulating film 2. The conductive thin film resistor 3 is the conductive thin film resistor 3 described in example 1. For example, the conductive thin film resistor 3 is metal Pt with a thickness of 0.2 μm and is formed by a conventional magnetron sputtering process.

Then, as shown in d) of fig. 3, the conductive thin film resistor 3 is processed to form a polygonal conductive thin film resistor 3 shown in c) of fig. 1, and

electrodes

3a and 3b at both ends. The conductive thin film resistor 3 is fabricated by conventional photolithography and Ion Beam Etching (IBE).

Then, as shown in e) of fig. 3, a second insulating film 4 is formed on the thin film resistor 3. The second insulating film 4 is the second insulating film 4 described in embodiment 2. For example, the second insulating film 4 is a silicon nitride film having a thickness of 0.4 μm, and is grown by a conventional PECVD (PECVD: plasma Enhanced Chemical Vapor deposition, chinese: plasma Enhanced Chemical Vapor deposition).

Then, as shown in f) of fig. 3 and a) of fig. 1, the second insulating film 4 and the first insulating film 2 below the second insulating film are processed to form the trench 8 and the window 4d. The trench 8 is formed to penetrate the second insulating film 4 and the first insulating film 2 thereunder in the depth direction, and the first main surface 1a of the substrate 1 is exposed at the bottom. The window 4d penetrates the second insulating film 4 in the depth direction, and the bottom exposes the surfaces of the

electrodes

3a and 3b. The processing of the second insulating film 4 and the first insulating film 2 below it may be performed separately or continuously. When the etching is performed separately, after the second insulating film 4 is etched by using the conventional photolithography, silicon nitride etching, and a matching process, the photolithography is performed again and the first insulating film 2 is etched by using the silicon oxide etching and the matching process. In the case of continuous etching, conventional photolithography may be performed only once, and then the second insulating film 4 and the first insulating film 2 may be continuously etched by dry etching and a matching process.

Then, as shown in g) of fig. 3 and a) of fig. 1, the substrate 1 is processed to form the cavity 6 below the heater 10 and the cantilever 7 (including 7a,7b,7c, and 7 d). Thus, the heater 10 is suspended in the air and connected to the substrate 1 only by the cantilever 7. The processing of the substrate 1 may be performed using conventional silicon processing techniques. For example, silicon is etched with a gas or plasma that has an etching effect on silicon. At this time, the gas or plasma reaches the surface of the substrate 1 through the channel 8 to perform etching. The gas is for example XeF2, or SF6, etc. The plasma is, for example, a plasma of SF6 or the like. For another example, silicon is etched with a liquid that has an etching effect on silicon. At this time, the gas or the like also reaches the surface of the substrate 1 through the trench 8 to be etched. Examples of the liquid include KOH (potassium hydroxide), TMAH (tetramethylammonium hydroxide), and the like.

By the processing shown in b) of fig. 3 to g) of fig. 3, the heater 10 composed of the first insulating film 2, the conductive thin film resistor 3 formed on the first insulating film 2, and the second insulating film 4a covering the main portion of the conductive thin film resistor 3 is formed. The heater 10 is suspended in the air and is connected to the substrate 1 only by the cantilever beam 7.

Then, as shown in h) of fig. 3 and a) of fig. 1, a getter film 5 is formed on the upper surface of the heater 10. The getter film 5 is the getter film 5 described in example 2. The area of the getter film 5 is smaller than that of the second insulating film 4 a. For example, the getter film 5 is a Ti-based non-evaporable getter material, including Ti — Mo, with a thickness of about 2 microns. The getter film 5 can be deposited on the second insulating film 4a by magnetron sputtering using a metal mask as described in example 5.

It is clear that the method for manufacturing the getter structure 5 described with reference to figure 3 can be used not only for manufacturing a single unit of getter structure 5 as shown in example 1, but also for manufacturing a plurality of units of getter structure 5 as shown in example 2.

As described above, this example provides another method for manufacturing a getter structure, suitable for manufacturing the getter structures shown in examples 1 and 2. The manufacturing method is simple and the manufacturing cost is low. A plurality of getter structures can be simultaneously manufactured on a semiconductor substrate, and the mass production is realized.

Example 4

Embodiment 4 of the present application provides a vacuum packaging structure of a MEMS device. Fig. 4 is a schematic sectional view of the present embodiment. In the present embodiment, in order to highlight the main idea of the present application, the schematic diagram of fig. 4 includes only the most basic elements.

As shown in fig. 4, a vacuum packaging structure 200 of a MEMS device of an embodiment of the present application includes: a vacuum package 30 (including 30a and 30 b), conductive terminals 32 (including 32a and 32 b) communicating with the inside and outside of the vacuum package 30b, a MEMS device 20 packaged inside the vacuum package 30, and a getter structure 100. The electrode 3 (not shown) of the getter structure 10 is in electrical communication with the conductive terminal 32b through the wire 31 b. The vacuum chamber 40 is formed inside the vacuum packing case 30.

The vacuum packaging case 30 is composed of a case 30a, a case 30b, and conductive terminals 32 (including 32a, 32 b) communicating the inside and outside of the vacuum packaging case 30 b. The vacuum package housing 30 is a standard component used for vacuum packaging of semiconductor devices and MEMS devices, and a vacuum chamber 40 is formed inside the vacuum package housing. The initial vacuum level of the vacuum chamber 40 corresponds to the vacuum level required for proper operation of the MEMS device 20. Conductive terminal 32a is a plurality of conductive terminals, each of which is connected to a respective electrode of MEMS device 20. The conductive terminal 32b is a plurality of conductive terminals, which are respectively connected to the electrodes of the getter structure 100.

The MEMS device 20 is a MEMS device that needs to operate under a certain vacuum atmosphere. For example, the MEMS device 20 may be one or more of the following MEMS devices: MEMS oscillators, MEMS pressure sensors, MEMS resonator filters, MEMS inertial sensors (MEMS gyroscopes, MEMS accelerometers, etc.), MEMS infrared imaging devices, and the like. The respective electrodes of the MEMS device 20 are in electrical communication with different conductive terminals 32a, respectively, via different conductive lines 31 a.

The getter structure 100 is the getter structure 100 described in examples 1 or 2. The getter structure 100 may be one or a plurality. Each getter structure 100 can comprise a single getter structure element as shown in example 1, or can comprise a plurality of getter structure elements as shown in example 2. The electrodes of the getter structure 100 are in electrical communication with different conductive terminals 32b through different conductive wires 31b, respectively.

At least one getter structure unit of the getter structure 100 can be activated immediately after the packaging of the vacuum packaging structure 200 is completed, and absorb the gas remained in the vacuum cavity 40, so that the vacuum degree of the vacuum cavity 40 meets the operation requirement of the MEMS device 20. At least one getter structure unit of the getter structure 100 may be activated after the packaging of the vacuum packaging structure 200 is completed for a certain time, absorbing the gas generated in the vacuum chamber 40 or entering the vacuum chamber 40, so that the deteriorated vacuum degree of the vacuum chamber 40 again meets the operation requirement of the MEMS device 20. The activation of the getter film 5 can be achieved by the conductive terminal 32b delivering electrical energy to the heater 10 to raise the temperature of the getter film 5 to its activation temperature. The simultaneous vacuum encapsulation of the plurality of getter structure units with the MEMS device 20 by the at least one getter structure unit allows to activate the getter film 5 in time when required. Thus, this embodiment allows the MEMS device 20 to be in a more desirable vacuum environment for a longer period of time than if the getter were activated only once. This means that not only can promote the performance stability and the reliability of MEMS device, can also prolong the life of MEMS device and the vacuum packaging structure whole part that contains MEMS device several times to reduce use cost. In addition, the getter film 5 of each getter structure unit can be activated for a plurality of times due to the self-contained heater 10. Although the gettering effect of the getter film 5 is reduced after the second and subsequent activations as compared to that after the first activation, it may play a role of increasing the degree of vacuum inside the vacuum chamber 40.

As described above, the package structure of the MEMS device provided by this embodiment includes the micro heater, so that the getter structure can be activated at any time when needed, thereby improving the performance stability and reliability of the MEMS device, and also prolonging the service life of the MEMS device and reducing the use cost thereof. The heater and the getter film are integrated, so the volume is small, and the space of an MEMS device packaging structure can be saved.

The present application has been described in conjunction with specific embodiments, but it should be understood that these descriptions are exemplary and not intended to limit the scope of the present application. Various modifications and adaptations of the present application may occur to those skilled in the art based on the spirit and principles of the application and are within the scope of the application.

Claims

1. A thin film getter structure having a microheater, comprising:

a substrate;

a heater formed on one main surface side of the substrate; and

a getter film formed on the surface of the heater,

wherein, the heater includes:

a first insulating film;

a second insulating film covering the thin film resistor,

wherein the content of the first and second substances,

the one main surface of the substrate has a cavity,

the part of the thermion bearing the getter film is positioned above the hollow hole,

2. Thin film getter structure according to claim 1, wherein,

the second insulating film has a thermal conductivity higher than that of the first insulating film.

3. Thin film getter structure according to claim 1 wherein,

the second insulating film includes a first portion and a second portion separated from each other by an isolation trench,

the first portion covers an area of the thin film resistor.

4. Thin film getter structure according to claim 3 wherein,

the area of the getter film formed at the first portion of the second insulating film is smaller than that of the first portion of the second insulating film.

5. Thin film getter structure according to any of claims 1 to 4,

wherein the thin film getter structure comprises two or more of the thermions and two or more of the getter films,

each getter film is arranged on the upper surface of the corresponding heater.

6. A vacuum packaging structure for a mems device, comprising:

thin film getter structure according to any of claims 1 to 5, encapsulated inside said vacuum encapsulation envelope,

7. A method of making a thin film getter structure having a microheater, comprising:

forming a heater on one main surface of a substrate;

a getter film is formed on the surface of the heater,

wherein the step of forming the thermions comprises:

forming a first insulating film on one main surface of the substrate;

forming a second insulating film covering the thin film resistor,

8. The manufacturing method according to claim 7,

the step of forming the thermions further comprises:

forming an isolation groove in the second insulating film, the isolation groove separating a first portion and a second portion of the second insulating film from each other,

wherein the first portion covers an area of the thin film resistor.

9. The manufacturing method according to claim 8,

10. The manufacturing method according to claim 7,