CN209930222U - Filter assembly - Google Patents

Abstract

A filter assembly includes a substrate, a back cover member, and a sonic oscillation assembly. The substrate is provided with a plurality of through silicon vias penetrating through the substrate; the back cover part is arranged on the lower surface of the substrate and covers the through silicon holes; the acoustic wave oscillation assembly is arranged on the upper surface of the substrate. The acoustic wave oscillating assembly includes: the device comprises a plurality of excitation electrodes, a passivation layer, a first wall, a second wall, a conducting layer, a plurality of metal plugs and a connecting component arranged on each metal plug. A plurality of first holes are formed in the first wall body on the passivation layer, and part of the surface of the passivation layer is exposed; the second wall body is arranged on the first wall body, a plurality of second holes are formed in the second wall body on the partial surface corresponding to the passivation layer, and the side walls of the first holes of the first wall body and part of the second wall body form an oscillation space.

Description

Filter assembly

Technical Field

The utility model provides a semiconductor technology field especially relates to a filter subassembly.

Background

The piezoelectric film (piezoelectric membrane) and the circuit of the filter element are both fabricated on the substrate, and the filter element should not be turned upside down during packaging, resulting in that the electrical signal can only be conducted outwards by wire bonding. The wire bonding method is disadvantageous for the preparation of the filter assembly due to the disadvantages of long interconnection delay, large inductance, low packaging efficiency and the like. At present, a wire bonding method is gradually replaced with a Through-Silicon Via (TSV) packaging technology, which has a shorter interconnection path, lower resistance and inductance, and more efficient signal and power transmission, and also has the advantages of not limiting the number of die stacks, etc., and the TSV technology is already adopted in complementary metal oxide semiconductor sensors (CMOS sensors) and memories, and is expected to be more and more widely applied to fundamental frequencies, radio frequencies, filters, etc. in the future.

TSV technology requires drilling a substrate to form a through-silicon via, which is completed before any semiconductor process, and thus has more technical challenges, such as difficulty in forming the through-silicon via. When the filter component is used for drilling holes due to the fact that the substrate is very thin, for example, the thermal expansion change is caused by the influence of the material of the substrate, the thermal expansion coefficients of various layer materials are not matched, and the problem of warping is caused; even more serious is the structural strength of the final product.

The background section is only used for illustrating the invention, and therefore the disclosure in the background section may include some known techniques which are not known to those skilled in the art. The disclosure in the "background" section does not represent that or the problems which may be solved by one or more embodiments of the present invention are known or appreciated by those of ordinary skill in the art prior to the filing of the present application.

SUMMERY OF THE UTILITY MODEL

In order to overcome the above-mentioned shortcomings, the present invention provides a filter assembly, which has a back cover on the back surface to protect the thin substrate from warpage in wafer level bumping (wafer level bumping process), thereby maintaining better structural strength.

To achieve the above object, the filter assembly of the present invention includes a substrate, a back cover member, and an acoustic wave device (acoustic wave device). The substrate is provided with an upper surface and a lower surface and is provided with a plurality of through silicon vias penetrating through the substrate; the back cover piece is arranged on the lower surface of the substrate and covers the through silicon holes; the acoustic wave oscillating assembly is disposed on the upper surface of the substrate. The acoustic wave oscillating assembly includes: a plurality of excitation electrodes (excitation electrodes) are arranged on the upper surface of the substrate and aligned to the through silicon vias of the substrate; the passivation layer is arranged on the upper surface of the substrate, part of the upper surface of the substrate is exposed, and a spacing distance is reserved between the passivation layer and the adjacent excitation electrode; the first wall body is arranged on the passivation layer and between every two adjacent excitation electrodes, a plurality of first holes (via) are formed in the first wall body on the passivation layer, and part of the surface of the passivation layer is exposed; the second wall body is arranged on the first wall body, a plurality of second holes are formed in the second wall body on the part of the surface corresponding to the passivation layer, and the second holes are aligned and communicated with the first holes, so that the side walls of the first holes of the first wall body and part of the second wall body form an oscillation space; the conductive layer (conductive layer) is arranged on the passivation layer exposed out of each first hole of the first wall body and each second hole of the second wall body; a plurality of metal plugs (metal plugs) are arranged in each first hole of the first wall body and each second hole of the second wall body and connected with the conductive layer; a connecting assembly is disposed on each metal plug.

Based on the above, the utility model discloses a filter assembly is provided with the back lid piece in the lower surface of substrate, but the front side of balanced filter assembly and the pressure that the back side received avoid warp deformation, and can protect the acoustic oscillation subassembly to suffer vacuum destruction and the pollution and the chemical damage that warp, developer arouse during carrying out wafer level lug technology.

Drawings

Fig. 1A is a schematic diagram illustrating a front side of a substrate having filter components in accordance with the techniques of the present invention.

Fig. 1B is a schematic diagram illustrating a back side of a substrate having a filter assembly, according to the techniques of the present invention.

Fig. 2A-2G are process flow diagrams illustrating a filter assembly according to the techniques of the present invention.

Detailed Description

In order to make the objects, technical features and advantages of the present invention more comprehensible to those skilled in the relevant art and to enable implementation of the present invention, accompanying drawings are provided herein to illustrate the technical features and embodiments of the present invention, and preferred embodiments are described below. The drawings referred to below are for illustrative purposes only and are not necessarily drawn to scale. The description of the embodiments related to the present invention will not be repeated, except for those skilled in the art.

The filter element described in the description of the embodiments of the present invention is a medium for filtering signals of a specific frequency, prevents noise interference of different frequencies, and functions mainly as a sound wave oscillation element. The Acoustic Wave oscillating elements can be divided into Surface Acoustic Wave (SAW) filters and Bulk Acoustic Wave (BAW) filters according to their differences; although surface acoustic wave filters are the mainstream in the market, with the demand for high frequency and high performance filtering products, the internal acoustic wave filters with higher price and better performance gradually become the trend for higher-order semiconductor devices.

Referring to fig. 1A and fig. 1B, fig. 1A is a schematic diagram of a front surface of a substrate with a filter element, and fig. 1B is a schematic diagram of a back surface of the substrate with the filter element. In the present invention, the filter assembly (not shown) is a wafer-level (wafer-level) processTo fabricate, a plurality of acoustic wave oscillating devices 100 are disposed on the upper surface 10A of the substrate 10, and a back cover 20 is attached to the lower surface 10B of the substrate 10. After the acoustic wave oscillating device 100 is fabricated on the substrate 10, a dicing (sawing) process is performed after the scribe lines 101 on the upper surface 10A and the scribe lines 102 on the lower surface 10B of the substrate 10 are aligned, so as to obtain a plurality of filter device dies (die). In the present invention, a back cover member 20, which is a dry film (dry film) having optical sensitivity, is attached to the lower surface 10B of the substrate 10, for example, a resin dedicated for lithography such as epoxy resin, polyimide resin, BCB resin, or acryl resin, so that the back cover member 20 is formed by patterning the resin by photolithography and thermosetting the patterned resin. Then, using a semiconductor process, an exposure and development process is performed on the dry film disposed on the lower surface 10B of the substrate 10, so that scribe lines 102 are formed on the dry film, and the scribe lines 102 correspond to the scribe lines 101 on the upper surface 10A of the substrate 10. In the embodiment applied to 4 inch substrates, the thickness of the back cover 20 is preferably 20 μm

40μm。

In one embodiment, when the acoustic wave device 100 is in the form of in-vivo acoustic wave, the substrate 10 is drilled to form the through-silicon via 10t and thus has a void, which is prone to warpage, vacuum damage and contamination in the subsequent wafer level packaging process, and the back cover 20 is attached to the bottom surface 10B of the substrate 10 to protect the acoustic wave device 100 and improve the warpage.

Fig. 2A to fig. 2G are process flow diagrams illustrating the filter assembly according to the present invention.

Referring to fig. 2A, a device number 10 is a substrate, hereinafter referred to as a substrate, and a plurality of excitation electrodes 12 are formed at predetermined positions (not shown) on an upper surface 10A of the substrate 10, wherein the excitation electrodes 12 are made of a piezoelectric material, preferably a metal, and in another embodiment, the piezoelectric material may be aluminum or an aluminum alloy with copper added. Next, the substrate 10 is turned upside down, and Through Silicon Vias (TSVs) 10t are formed on the lower surface 10B of the substrate 10 at positions corresponding to each of the excitation electrodes 12 by using a semiconductor process, such as an exposure, development, and etching process, on the lower surface 10B of the substrate 10. In another embodiment, a via-first (via-first) process may be used to form the through-silicon vias 10t from the bottom surface 10A of the substrate 10 corresponding to the position of each excitation electrode 12.

Next, the substrate 10 is turned upside down, that is, the upper surface 10A of the substrate 10 faces upward in the drawing and the lower surface 10B faces downward in the drawing. A passivation layer (11) is formed on the upper surface 10A of the substrate 10 and covers the plurality of excitation electrodes 12 on the substrate 10, and then a portion of the passivation layer 11 corresponding to the excitation electrodes 12 is removed by a semiconductor process to expose a portion of the upper surface 10A of the substrate 10 and the plurality of excitation electrodes 12.

Please refer to fig. 2B. In fig. 2B, a back cover member 20 is formed on the lower surface 10B of the substrate 10. The purpose of the dry film as the backside lid 20 is to cover the through-silicon vias 10t of the substrate 10, so as to prevent the through-silicon vias 10t from being contaminated by impurities in the subsequent processes. In addition, the back cover member 20 can also increase the strength of the entire substrate 10, so that the substrate 10 can withstand the pressure during the process of manufacturing the acoustic wave oscillating device 1 on the substrate 10, and the substrate 10 does not have the problem of collapsing or warping. It should be noted that the step of forming the back cover member 20 on the lower surface 10B of the substrate 10 may be performed before or after the step of forming the passivation layer 11 on the upper surface 10A of the substrate 10, and the order of the formation steps is not limited herein.

Next, the fabrication of the acoustic wave oscillation device 100 is started. Referring to fig. 2C, a polymer material is formed on the passivation layer 11 as the first wall 14 by a semiconductor process, a portion of the polymer material is removed by the same processes of exposure and development in the semiconductor process, and a first hole 140 is formed in the first wall 14 to expose a portion of the surface of the passivation layer 11, a portion of the upper surface 10A of the substrate 10 and the plurality of excitation electrodes 12, and the polymer material remained between the adjacent excitation electrodes 12.

Please refer to fig. 2D. In fig. 2D, a second wall 16 is formed on the first wall 14 in the same manner as the first wall 14, in which the polymer material used as the second wall 16 is formed on the first wall 14, and then a semiconductor process is used to remove a portion of the polymer material to form the second wall 16. In the present invention, the second hole 160 in the second wall 16 is aligned with the first hole 140 in the first wall 14, and the polymer material covering the excitation electrode 12 can be regarded as the cover 161, so that the space surrounded by the cover 161 of the first wall 14 and the second wall 16 constitutes the oscillation space 120. In the present invention, the oscillation space 120 may provide a space for the excitation electrode 12 located in the oscillation space 120 to easily oscillate to propagate the surface acoustic wave. The first wall 14 between the adjacent excitation electrodes 12 can be used as a spacer (spacer) to support the oscillation space 120, so as to avoid the oscillation space 120 from warping.

In one embodiment, the first hole 140 and the second hole 160 are preferably reverse tapered, and the X radial width of the lower end opening of the second hole 160 is preferably greater than the X radial width of the lower end opening of the first hole 140. Due to the anchoring effect (anchoreffect), the adhesion between the conductive layer 13, the first wall 14, and the second wall 16 can be improved, and the welding capability of the connecting member 180 can be increased.

In the present invention, a polymer material having optical activity and being cured by heat and having excellent mechanical strength and chemical resistance is used as the material of the first wall 14 and the second wall 16. The polymer material may be a resin such as an epoxy resin, a polyimide resin, a BCB resin, or an acrylic resin. The thickness of the first wall 14 and the second wall 16 is preferably several 10 μm, and more preferably 30 μm.

Please refer to fig. 2E. In fig. 2E, a conductive layer 13 is formed on the surface of the passivation layer 11 exposed by the first wall 14 and the second wall 16 by sputtering (sputtering). In the present invention, the material of the conductive layer 13 may be nickel, copper, gold, or an alloy of the above metals, but is not limited thereto.

Please refer to fig. 2F. In fig. 2G, a metal plug (metal plug)18 is formed on the exposed conductive layer 13 of the first wall 14 and the second wall 16 by using a semiconductor process technology, and the metal plug may be formed by deposition or sputtering. In the present invention, the material of the metal plug 18 may be the same as or different from that of the conductive layer 13, and may be copper, nickel, tin, gold, silver, or other metals. In the present invention, the height of the metal plug 18 is preferably 60 μm

And 90 μm. In another preferred embodiment, before forming the metal plugs 18, a metal seed layer (not shown) is formed on the conductive layer 13 exposed by the first wall 14 and the second wall 16 and on the sidewalls of the first wall 14 and the second wall 16, and then a metal layer is formed on the metal seed layer by using a sputtering or deposition process, so that the metal plugs 18 are formed in the first wall 14 and the second wall 16 by the metal seed layer and the metal seed layer.

Please refer to fig. 2G. In fig. 2G, a connecting component 180 is formed on the metal plug 18. In the present invention, the connecting component 180 may be a solder bump (solder bump) or a solder ball (solder ball), and in one embodiment, the solder paste may be used to perform a reflow process to complete the wiring interconnection.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention; while the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (8)

1. A filter assembly, comprising:

a substrate having an upper surface and a lower surface and having a plurality of through-silicon vias extending through the substrate;

a back cover member disposed on the lower surface of the substrate and covering the through-silicon-via; and

a sonic oscillating assembly disposed on the upper surface of the substrate, the sonic oscillating assembly comprising:

a plurality of excitation electrodes arranged on the upper surface of the substrate and aligned with the through-silicon-vias of the substrate;

a passivation layer disposed on the upper surface of the substrate to expose a portion of the upper surface of the substrate, the passivation layer having a spacing distance from the adjacent excitation electrode;

the first wall is arranged on the passivation layer and between every two adjacent excitation electrodes, a plurality of first holes are formed in the first wall on the passivation layer, and part of the surface of the passivation layer is exposed;

the second wall body is arranged on the first wall body, a plurality of second holes are formed in the second wall body on the part of the surface corresponding to the passivation layer, and the second holes are aligned with and communicated with the first holes, so that a side wall of the first hole of the first wall body and part of the second wall body form an oscillation space;

the conducting layer is arranged on the passivation layer exposed out of each first hole of the first wall body and each second hole of the second wall body;

a plurality of metal plugs, which are arranged in each first hole of the first wall body and each second hole of the second wall body and are connected with the conducting layer; and

and the connecting component is arranged on each metal plug.

2. The filter assembly of claim 1, wherein the lower surface of the substrate is provided with dicing streets.

3. The filter assembly of claim 1, wherein the back cover member is a dry film.

4. The filter assembly of claim 1, wherein an X radial width of an opening of the second aperture of the second wall is greater than an X radial width of an opening of the first aperture of the first wall.

5. The filter assembly of claim 1, wherein the metal plug is copper, nickel, tin, or silver.

6. The filter assembly of claim 1, wherein the first wall and the second wall are polymeric materials.

7. The filter assembly of claim 1 wherein said connecting elements are solder balls.

8. The filter assembly of claim 1, wherein the portion of the second wall forms a cover portion of the oscillation space.

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