CN116022719A - Getter film structure - Google Patents

Abstract

The present invention provides a getter film structure comprising: a thin getter layer and a plurality of continuous pores extending in an in-plane direction of the thin getter layer; the pores have openings at the sides of the getter sheet. The invention can increase the specific surface area of the getter film by forming the transverse channels of the getter film in the gaps in the film surface direction, so that the gettering capability and speed of the getter film are greatly improved. The getter film structure can have sufficient mechanical strength and workability is ensured. Compared with the common getter film, the invention can achieve the same gettering effect by using less getters, thereby reducing the overall cost of the device.

Description

Getter film structure

Technical Field

The invention belongs to the field of MEMS design and manufacture, and particularly relates to a getter film structure.

Background

It is well known that some semiconductor devices, particularly those of the microelectromechanical systems (MEMS: micro Electro Mechanical Systems), require packaging to operate in a vacuum environment. Such as MEMS acceleration sensors, gyroscopes, vacuum gauges, etc. with high-speed moving (displacement or vibration or rotation) parts, require the moving parts to be enclosed in a relatively stable vacuum environment. For another example, a MEMS pressure sensor having a vacuum chamber is required, and a high vacuum is required in the vacuum chamber, and the vacuum degree thereof needs to be kept stable. In addition, some infrared sensors also require the device to be packaged in a vacuum chamber with a relatively high vacuum level.

On the one hand, achieving a higher vacuum package is inherently challenging. Because, during the encapsulation process, some residual gas is often trapped in the vacuum chamber. For this reason, it is often necessary to enclose a getter in the vacuum chamber, activate the getter at the same time as packaging, or activate the getter after packaging is completed, and absorb the residual gas in the vacuum chamber, so as to achieve a higher vacuum required for the operation of the device. Getters (getters), also known as getters, refer in the field of vacuum technology to materials that are capable of efficiently adsorbing and immobilizing certain or certain gas molecules. The getter material is typically a porous structure, and when reactive gas molecules collide with the surface of the clean getter material, some of the gas molecules are adsorbed, which is the physical adsorption of the getter material; some of the gas molecules will chemically react with the getter material to form a stable solid solution, which is the chemisorption of the getter material. And the gas molecules can continuously diffuse into the material, thereby achieving the aim of pumping a large amount of active gas. Generally, the adsorption effect of the getter on the surface layer is better and the adsorption is faster, so the larger the surface area of the getter is, the better the adsorption performance (i.e., the larger the amount of adsorbable gas is, the faster the adsorption rate is). This is also why the getter is made of porous material. The thin film type getter structure has the advantages of small occupied space, easy compatibility with the device technology, convenience for wafer level packaging, suitability for mass production and the like.

However, the existing getter has a small specific surface area, so that the getter performance is difficult to improve.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a thin film structure of a getter, which is used for solving the problem that the specific surface area of the getter in the prior art is small, so that the gettering performance of the getter is difficult to be improved.

To achieve the above and other related objects, the present invention provides a getter film structure comprising: a thin getter layer and a plurality of continuous pores extending in an in-plane direction of the thin getter layer; the pores have openings on the sides of the thin getter layer.

Optionally, the getter film structure comprises: n thin layers of getter are stacked in sequence, wherein N is more than or equal to 2, the pore is formed in the in-plane direction of each thin layer of getter, and the pore is provided with an opening at the side face of the thin layer of getter.

Optionally, the apertures extend through both sides of the thin getter layer in an in-plane direction of the thin getter layer to form openings on both sides of the thin getter layer to form lateral channels in the thin getter layer.

Optionally, the projections of the apertures in adjacent two thin layers of getter have an intersection within the thin layers of getter.

Optionally, projections of apertures in adjacent two thin layers of getter perpendicularly intersect within the thin layers of getter.

Optionally, the length of the aperture in the in-plane direction of the thin getter layer is not less than the thickness of the thin getter layer.

Optionally, the width of the pores in the in-plane direction of the thin getter layer is not less than 50nm.

Optionally, the material of the getter thin layer includes one of Zr-based non-evaporable getter and Ti-based non-evaporable getter.

Optionally, the Zr-based non-evaporable getter comprises one of Zr-V-Fe, zr-Al and Zr-Mn-Fe, and the Ti-based non-evaporable getter comprises one of Ti-Fe-V-Mn, ti-Mo and Ti-Zr-Ni.

Optionally, the thickness of the getter thin layer is 100 nm-1 μm.

As described above, the getter film structure of the present invention has the following advantageous effects:

the invention provides a getter film structure, wherein transverse channels of the getter film are formed through gaps in the in-plane direction, so that the specific surface area of the getter film can be increased, and the gettering capability and speed of the getter film can be greatly improved. On the other hand, the getter film structure of the invention can have sufficient mechanical strength, and the usability is ensured. On the other hand, compared with the common getter film, the invention can achieve the same gettering effect by using less getters, thereby reducing the overall cost of the device.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the application and 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 apparent that the drawings in the following description are only some of the embodiments of the present application.

Fig. 1 is a schematic perspective view showing a getter film structure according to an embodiment of the present invention, fig. 2, 3, 4 and 5 are schematic cross-sectional views of the getter film structure at A-A 'and fig. 6, 7, 8 and 9 are schematic cross-sectional views of the getter film structure at B-B' in the respective steps of the method for manufacturing the getter film structure according to the embodiment of the present invention.

Description of element reference numerals

10. Substrate board

20. Getter film structure

21. First layer of getter sheet

21' first getter layer

31. First layer of pattern sacrificial layer

22. Second layer of getter sheet

22' second getter layer

32. Second layer of pattern sacrificial layer

23. Third layer getter sheet

23' third layer getter sheet

33. Third layer of pattern sacrificial layer

24. Fourth getter layer

24' fourth getter layer

34. Fourth layer of pattern sacrificial layer

25. Fifth layer getter lamina

25' fifth layer getter lamina

41. Pores of the material

Detailed Description

Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention.

As described in detail in the embodiments of the present invention, the cross-sectional view of the device structure is not partially enlarged to a general scale for convenience of explanation, and the schematic drawings are only examples, which should not limit the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in actual fabrication.

For ease of description, spatially relative terms such as "under", "below", "beneath", "above", "upper" and the like may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that these spatially relative terms are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures. Furthermore, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers or one or more intervening layers may also be present.

In the context of this application, a structure described as a first feature being "on" a second feature may include embodiments where the first and second features are formed in direct contact, as well as embodiments where additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

It should be noted that, the illustrations provided in the present embodiment merely illustrate the basic concept of the present invention by way of illustration, and only the components related to the present invention are shown in the drawings rather than the number, shape and size of the components in actual implementation, and the form, number and proportion of each component in actual implementation may be arbitrarily changed, and the layout of the components may be more complex.

Sputtering is a common technique for forming getter film structures. In the getter film structure formed by the sputtering method, continuous voids are easily formed in the film thickness direction, but it is difficult to form continuous voids in the film in-plane direction. However, when the thickness of the getter film reaches a certain level, it becomes difficult to realize communication from the film surface to the pores of the film bottom layer, and the pores become small inside the film. Thus, not only the surface area of the film is limited, but also the speed at the time of adsorption is slow. Therefore, when the film thickness reaches a certain level, the effect of increasing the getter adsorption property by increasing the film thickness is reduced. Moreover, getters are generally costly, increasing the thickness of the getter film means increasing the cost of the entire packaged device. On the other hand, the pores and thus the surface area of the getter film can be increased by decreasing the density of the getter film. However, too loose a density may deteriorate the mechanical properties of the film, and chipping and peeling of the film may be easily caused, thereby affecting the usability.

As shown in fig. 1 and 9, fig. 9 is a schematic cross-sectional structure at B-B' in fig. 1, where the present embodiment provides a getter film structure, and the getter film structure includes: a thin getter layer and a plurality of continuous pores extending in an in-plane direction of the thin getter layer; the pores have openings on the sides of the thin getter layer.

In one embodiment, the getter film structure is disposed on a substrate, which may be a silicon substrate, a glass substrate, a quartz substrate, a metal cover plate in MEMS packaging, or the like.

In one embodiment, the getter film structure comprises: n thin layers of getter are stacked in sequence, wherein N is more than or equal to 2, the pore is formed in the in-plane direction of each thin layer of getter, and the pore is provided with an opening at the side face of the thin layer of getter.

In one embodiment, the holes penetrate through both sides of the thin getter layer in the in-plane direction of the thin getter layer to form openings on both sides of the thin getter layer, thereby forming transverse channels in the thin getter layer, wherein the transverse channels are of a structure with two ends penetrated, so that the flow speed of gas can be effectively increased, and the air suction speed of the thin getter layer can be increased.

In one embodiment, the projections of the apertures in adjacent two thin layers of getters within the thin layers of getters have intersections. For example, the intersection angle of the projections of the apertures in two adjacent patterned getter sheets within the getter sheet plane may be 30 degrees, 45 degrees, 60 degrees, 90 degrees, etc., and in one implementation, the projections of the apertures in two adjacent getter sheets within the getter sheet plane intersect perpendicularly.

In one embodiment, the length of the aperture in the in-plane direction of the thin getter layer is not less than the thickness of the thin getter layer, thereby ensuring at least the gettering capability and gettering speed of the thin getter layer.

In an embodiment, the width of the pores in the in-plane direction of the getter thin layer is not less than 50nm, for example, the width of the pores in the in-plane direction of the getter thin layer may be 80nm, 100nm, 150nm, etc., which may ensure the specific surface area of the getter thin layer on the one hand and the mechanical strength of the getter thin layer on the other hand.

In one embodiment, the material of the thin getter layer includes one of a Zr-based non-evaporable getter and a Ti-based non-evaporable getter. Specifically, the Zr-based non-evaporable getter comprises one of Zr-V-Fe, zr-Al and Zr-Mn-Fe, and the Ti-based non-evaporable getter comprises one of Ti-Fe-V-Mn, ti-Mo and Ti-Zr-Ni.

In one embodiment, the thickness of the thin getter layer is 100nm to 1 μm, and the thickness of the thin getter layer may be, for example, 200nm, 500nm, 800nm, etc.

As shown in fig. 1 and 9, the process for preparing a 5-layer getter film structure 20 is described in detail below, wherein the getter film structure 20 includes a first layer of getter film 21', a second layer of getter film 22', a third layer of getter film 23', a fourth layer of getter film 24', and a fifth layer of getter film 25'. Each thin getter layer is penetrated and divided into a plurality of strip-shaped getter patterns by the pores 41, and the patterns of each thin getter layer are mutually perpendicular to the patterns of the thin getter layers of the adjacent layers, so that the mechanical strength of the finally prepared thin getter film structure is effectively improved. At the same time, since the pores 41 in the adjacent thin getter layers are also perpendicular to each other, the gettering capability of the thin getter film structure can be effectively improved.

As shown in fig. 1 to 9, the present embodiment further provides a method for manufacturing a getter film structure, the method comprising the steps of: providing a substrate, forming a first getter thin layer above one main surface of the substrate, and forming a plurality of grooves which are arranged at intervals in the first getter thin layer so as to form a getter thin layer; filling a pattern sacrificial layer in the groove, and forming a second getter thin layer on the pattern sacrificial layer and the pattern getter thin film; the patterned sacrificial layer is removed to form pores 41 in an in-plane direction of the thin getter layer, the pores 41 having openings at sides of the thin getter layer.

In one embodiment, the manufacturing method may include the steps of: 1) Forming a first getter thin layer over the substrate, forming a plurality of trenches in the getter thin layer in spaced apart arrangement to form a getter thin layer; 2) Filling a first pattern sacrificial layer in the groove of the getter thin layer; 3) Repeating the steps to form N getter thin layers and N-1 pattern sacrificial layers, wherein N is more than or equal to 2, and the pattern sacrificial layers do not need to be formed on the getter thin layers at the topmost layer; 4) N-1 of the patterned sacrificial layers are removed to form voids 41 in the in-plane direction of each of the thin getter layers, the voids having openings at the sides of the thin getter layers.

In one embodiment, the substrate may be a silicon substrate, a glass substrate, a quartz substrate, a metal cover plate in MEMS packaging, or the like.

In one embodiment, the apertures extend through both sides of the thin getter layer in an in-plane direction of the thin getter layer to form openings on both sides of the thin getter layer.

In one embodiment, the projections of the apertures in adjacent two thin getter layers on the substrate have an intersection. In one specific implementation, the projections of the apertures in adjacent two thin getter layers perpendicularly intersect on the substrate.

In one embodiment, the length of the aperture in the in-plane direction of the thin getter layer is not less than the thickness of the thin getter layer, thereby ensuring at least the gettering capability and gettering speed of the thin getter layer.

In an embodiment, the width of the pores in the in-plane direction of the getter thin layer is not less than 50nm, for example, the width of the pores in the in-plane direction of the getter thin layer may be 80nm, 100nm, 150nm, etc., which may ensure the specific surface area of the getter thin layer on the one hand and the mechanical strength of the getter thin layer on the other hand.

In one embodiment, before the first getter layer is formed, the method further comprises the step of: a bottom layer getter layer is formed over one major surface of the substrate, which may or may not be patterned and gettered through the apertures above it (the apertures of the first layer getter layer) to improve the gettering capability of the getter film structure while making better use of space.

In one embodiment, the thin getter layer is formed using a sputtering method or a vacuum evaporation method.

In one embodiment, the method of removing the patterned sacrificial layer includes one of a liquid solvent dissolution method and a gas plasma etching method.

In one embodiment, the sacrificial pattern layer includes one of a pattern formed of photoresist and a pattern formed of polyimide.

In one embodiment, the patterned sacrificial layer comprises a pattern formed of a silicon compound having a selectivity ratio, for example greater than 50:1, in the same etching process as the thin getter layer.

In one embodiment, the material of the thin getter layer may be a Zr-based non-evaporable getter, such as Zr-V-Fe, zr-Al, zr-Mn-Fe, etc., or a Ti-based non-evaporable getter, such as Ti-Fe-V-Mn, ti-Mo, ti-Zr-Ni, etc.

In one embodiment, the thickness of the thin getter layer is 100nm to 1 μm, and the thickness of the thin getter layer may be, for example, 200nm, 500nm, 800nm, etc.

As shown in fig. 1 to 8, fig. 1 is a schematic perspective view of the getter film structure 20 prepared in this embodiment, fig. 2, 3, 4, and 5 are schematic views of the cross-sectional structure at A-A 'in the corresponding step, and fig. 6, 7, and 8 are schematic views of the cross-sectional structure at B-B' in the corresponding step. The process of preparing a 5-layer getter film structure 20 is described in detail below.

As shown in fig. 2, step 1) is first performed to provide a substrate 10, and a first thin getter layer 21 is sputter deposited on the substrate 10 at room temperature, wherein the thickness of the thin getter layer may be 100nm to 1 μm. The getter thin layer is made of Zr-based non-evaporable getter or Ti-based non-evaporable getter. Of course, a bottom getter layer (not shown) may also be formed over one of the main faces of the substrate 10 before the first getter layer 21 is prepared.

As shown in fig. 3, step 2) is then performed to pattern the first getter layer 21 to form a first getter layer 21', thereby forming a desired pattern of grooves on the surface of the first getter layer 21, wherein the grooves may completely penetrate the first getter layer 21' in the thickness direction or may not penetrate the first getter layer 21' in the thickness direction, and a portion of the first getter layer 21 remains at the bottom of the grooves. The width of the grooves can be 50 nm-1 mu m, the number of the grooves is not less than 2, and the grooves can be specifically designed according to actual requirements. The patterning process may use one of an etching method or a hard mask method. The etching method comprises spin-coating photoresist on the first getter thin layer 21, exposing, developing, etching to form required grooves on the first getter thin layer 21, and removing the photoresist. The hard mask method is to use a metal mask with patterns, firstly deposit a layer of metal on the surface of a first layer of getter thin layer 21 as a mask, then use an etching method to pattern the metal mask so as to form the metal mask with patterns, then etch the getter thin layer so as to form the patterns of grooves on the getter thin layer, and finally remove the metal mask.

As shown in fig. 4, step 3) is performed next, and photoresist is filled in the trench of the first getter thin layer 21 as the first pattern sacrificial layer 31, and the photoresist filling method may be spin coating process or the like.

As shown in fig. 5, step 4) is then carried out, and a second thin getter layer 22 is sputter deposited again on top of the first thin getter layer 21', with a thickness comprised between 100nm and 1 μm.

As shown in fig. 6, step 5) is then performed to pattern the second getter layer 22 to form a second getter layer 22'. The pattern of the second getter layer 22 'is perpendicular to the pattern of the first getter layer 21'. If the getter layers are two in total (n=2), the removal of the sacrificial layer can be performed after this step is completed. However, the getter thin layers of the present example are 5 layers in total, so the following steps are required.

As shown in fig. 7, step 6) is performed, and after patterning the second getter thin layer 22, the trench of the second getter thin layer 22 is filled with photoresist as the second pattern sacrificial layer 32.

As shown in fig. 8, step 7) is then performed, and steps 1) to 6) are repeated until the third getter layer 23' is formed based on the third getter layer 23, the third pattern sacrificial layer 33 is formed based on the fourth getter layer 24, the fourth getter layer 24', the fourth pattern sacrificial layer 34 is formed based on the fourth getter layer 24, and the fifth getter layer 25' is formed based on the fifth getter layer 25. The trenches of the fifth getter layer 25' do not need to be filled with a patterned sacrificial layer. The pattern of each getter layer is perpendicular to the pattern of the adjacent getter layers, thereby effectively increasing the mechanical strength of the final getter film structure 20.

As shown in fig. 9, step 8) is finally performed, after the deposition and patterning of five getter thin layers are completed, the wafer is placed in an organic cleaning tank for soaking, and the patterned sacrificial layer is removed by a wet method, so as to finally realize the getter thin film structure 20 shown in fig. 1 and having the pores 41 (transverse channels), wherein in this embodiment, the projections of the pores 41 of two adjacent getter thin layers on the substrate 10 are vertical. The getter film structure 20 prepared using this scheme allows for the adsorption of greater amounts of gas and a faster gettering rate than normal film getters.

As described above, the method for manufacturing the getter film structure 20 of the present invention has the following advantageous effects:

the present invention provides a getter film structure 20, wherein transverse channels of the getter film are formed by voids in the in-plane direction, so that the specific surface area of the getter film can be increased, and the gettering capability and speed of the getter film can be greatly improved. On the other hand, the getter film structure 20 of the invention can have sufficient mechanical strength, and workability is ensured. On the other hand, compared with the common getter film, the invention can achieve the same gettering effect by using less getters, thereby reducing the overall cost of the device.

Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.

Claims (10)

1. A getter film structure, wherein said getter film structure comprises:

a thin getter layer and a plurality of continuous pores extending in an in-plane direction of the thin getter layer;

the pores have openings on the sides of the thin getter layer.

2. The getter film structure as recited in claim 1, wherein the getter film structure comprises: n thin layers of getter are stacked in sequence, wherein N is more than or equal to 2, the pore is formed in the in-plane direction of each thin layer of getter, and the pore is provided with an opening at the side face of the thin layer of getter.

3. The getter film structure of claim 2 wherein the apertures extend through both sides of the getter film in an in-plane direction of the getter film to form openings on both sides of the getter film to form lateral channels in the getter film.

4. The getter film structure of claim 2 wherein the projections of the apertures in adjacent two getter sheets have intersections within the getter sheet plane.

5. The getter film structure of claim 4 wherein the projections of the apertures in adjacent two getter sheets intersect perpendicularly within the getter sheet plane.

6. The getter film structure of claim 1 wherein the length of the aperture in the in-plane direction of the getter film is not less than the thickness of the getter film.

7. The getter film structure of claim 1 wherein the width of the pores in the in-plane direction of the thin getter layer is not less than 50nm.

8. The getter film structure as recited in claim 1, wherein the material of the getter film comprises one of Zr-based non-evaporable getters and Ti-based non-evaporable getters.

9. The getter film structure as recited in claim 8, wherein the Zr-based non-evaporable getter comprises one of Zr-V-Fe, zr-Al, and Zr-Mn-Fe, and wherein the Ti-based non-evaporable getter comprises one of Ti-Fe-V-Mn, ti-Mo, and Ti-Zr-Ni.

10. The getter film structure as recited in claim 1, wherein the thin getter layer has a thickness of 100nm to 1 μm.

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