KR20060102419A - Fabrication methods of wafer level fbar package and fbar duplexer by using the same - Google Patents

Abstract

The present invention relates to a method for manufacturing a thin film bulk acoustic resonator (FBAR) package and a method for manufacturing a FBAR duplexer package using the same, the method comprising: forming a plurality of FBARs each comprising a piezoelectric layer and an upper and lower electrodes on a wafer; Forming a connection pad each connected to an electrode, forming a photoresist on the upper surface of the wafer, and selectively removing the photoresist to form a sidewall structure surrounding each of the FBARs; Exposing a region of each of the connection pads, laminating a dry film resist on top of the sidewall structure, selectively removing the dry film to form the roof structure, and the sidewall structure and the roof. Forming a protective cap to seal each FBAR by curing the structure And, it provides a wafer level package FBAR manufacturing method comprising the step of cutting the wafer into individual FBAR element unit having the protective cap.

Thin film bulk acoustic resonator (FBAR), duplexer, wafer level package

Description

FABRICATION METHODS OF WAFER LEVEL FBAR PACKAGE AND FBAR DUPLEXER BY USING THE SAME}

1 shows a schematic structure of a conventional duplexer.

2A and 2B are cross-sectional views illustrating a conventional FBAR duplexer package, respectively.

3A to 3G are cross-sectional views showing a wafer level FBAR package manufacturing process according to an embodiment of the present invention.

4A to 4D are cross-sectional views illustrating a method of manufacturing a FBAR duplexer package according to an embodiment of the present invention.

<Code Description of Main Parts of Drawing>

31: wafer 33: sacrificial material

35: FBAR element 36: connection pad

37: photoresist 38: dry film resist

39: protective cap 45: wafer-level FBAR package

42: adhesive layer 46: wire

47: preliminary resin molding 48: EMC molding

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film bulk acoustic resonator (FBAR) package, and more particularly, to a wafer level FBAR package manufacturing method capable of implementing a simpler process and an FBAR duplexer package using the same.

In general, an FBAR element refers to a filter element including an upper and lower electrodes and a piezoelectric layer therebetween on a semiconductor substrate. In general, the FBAR device has various types of isolation structures, such as a Bragg reflector structure and an air gap structure, in the substrate region corresponding to the active region so that acoustic waves of the piezoelectric layer are not affected by the substrate.

Such FBAR devices are implemented in various types of packages. In particular, the FBAR duplexer includes a FBAR filter unit for transmitting and receiving, and a package substrate for implementing various circuits and input / output terminals for duplexing the same. That is, as shown in FIG. 1, the FBAR duplexer is connected to each filter and a face shifter (indicated by "λ / 4") connected between the transmission / reception bandpass FBAR filters (Tx, Rx) and the filters (Tx, Rx). It includes connected external terminals (P1, P2).

In the FBAR duplexer package, a PCB substrate and an LTCC substrate are mainly used as the package substrate in order to implement a complicated circuit pattern and an external terminal. 2A and 2B show schematic cross-sectional structures of a conventional FBAR duplexer package.

Referring to FIG. 2A, a duplexer package in which FBAR filters 5a and 5b for transmitting and receiving are disposed on a PCB substrate 1 is illustrated. The resin molding part 7 is formed on the PCB substrate through an EMC molding process.

The FBAR filters 5a and 5b for transmission and reception shown in Fig. 2A are provided in a wafer level package. That is, in the manufacturing process of the FBAR device, it is provided in a package implemented form in each FBAR device at the wafer level. For example, the wafer level FBAR package may be referred to the wafer level package described in Korean Patent Application No. 2003-63556 filed on Feb. 15, 2015 filed by the same applicant as the present application.

In general, the wafer-level FBAR packages 5a and 5b not only have a complicated connection structure but also use a substrate such as a silicon substrate as a protective cap structure for structural stability, so that the manufacturing process is very complicated.

On the contrary, a package using a conventional LTCC substrate includes LTCC substrates 11a and 11b in which various circuit patterns are implemented as shown in FIG. 2B. The FBAR filters 15a and 15b for transmitting and receiving are respectively die-bonded to the cavity regions of the LTCC substrates 11a and 11b and connected to predetermined circuit patterns 12 provided to the LTCC substrates 11a and 11b by the wires 16. do. In this package 20, the FBAR filters 15a and 15b for transmitting and receiving are protected by the LTCC substrates 11a and 11b and the leads 19, respectively, so that the wafer-level package process for the FBAR element itself is not required. There is this.

However, the LTCC substrate has a problem in that twisting is caused during firing, so that bonding with the lead is poor, and since a multilayer LTCC substrate is used, leakage of the package itself is serious.

On the other hand, a package using a PCB substrate is advantageous over an LTCC substrate package in terms of cost and production yield, but has a disadvantage in that a wafer-level package process for each FBAR device is complicated, and silicon used as a cap structure for structural stability Since the substrate and the like are poor in workability, it is difficult to precisely manufacture the manufacturing process, which may cause a defect in the wire bonding process.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide a wafer level FBAR package manufacturing method capable of precise processing while simplifying the process at the wafer level.

Another object of the present invention is to provide a novel FBAR duplexer package manufacturing method capable of reinforcing the structural stability of each transmit and receive filter package obtained in the wafer-level FBAR package manufacturing method.

In order to realize the above technical problem, the present invention,

Forming a plurality of FBARs each comprising a piezoelectric layer and an upper and lower electrodes on the wafer, forming a connection pad respectively connected to the upper and lower electrodes on the wafer, forming a photoresist on the upper surface of the wafer, and Selectively removing the photoresist to form a sidewall structure surrounding each of the FBARs, wherein a portion of each connection pad is exposed to the outside of the sidewall structure; and a dry film resist on top of the sidewall structure. : Stacking DFR), selectively removing the dry film resist to form the roof structure, and forming a protective cap for sealing each FBAR by curing the sidewall structure and the roof structure. And cutting the wafer into individual FBAR device units having the protective cap. Provided is a method for manufacturing a perlevel FBAR package.

Advantageously, forming the plurality of FBARs on the wafer comprises: forming a plurality of cavities on the wafer, filling the cavity with a sacrificial material to have a flat top surface with the wafer top surface, at least And sequentially forming a lower electrode, a piezoelectric layer, and an upper electrode on the cavity region. In this case, the package manufacturing method further includes removing the sacrificial material using a via hole.

Preferably, removing the sacrificial material is performed after forming the sidewall structure and before laminating the dry film resist. In the present embodiment, after removing the sacrificial material and before laminating the dry film resist, the method may further include adjusting a resonance frequency of each FBAR by partially etching the upper electrode.

Preferably, the forming of the protective cap may be a step of curing the sidewall structure and the roof structure using a thermal curing or UV-curing method.

The present invention also provides a novel method for manufacturing a FBAR duplexer package. The FBAR duplexer package manufacturing method includes a FBAR having a piezoelectric layer and a top and bottom electrodes formed on a substrate, a connection pad connected to the top and bottom electrodes, and a region of the connection pad, respectively, being formed on the substrate so as to be located outside the Providing a transmission / reception FBAR package each including a protective cap for sealing an FBAR, die-bonding the transmission / reception FBAR package to a package substrate on which a duplexing circuit is implemented, and the FBAR package of the transmission / reception. Wire bonding each of the exposed connection pad areas and the designated areas of the duplexing circuit pattern, and forming a preliminary resin molding unit outside the protective FBAR package protective cap using an encapsulating agent, and the resin molding Forming an EMC molding on the portion.

As the FBAR package for transmission and reception employed in the present invention, each of the FBAR packages obtained by the above-described method for manufacturing a wafer-level FBAR package can be used.

Hereinafter, with reference to the accompanying drawings, the present invention will be described in more detail.

3A to 3G are cross-sectional views showing a wafer level FBAR package manufacturing process according to an embodiment of the present invention.

In the method according to the present invention, as shown in FIG. 3A, a plurality of FBARs 35 are formed by sequentially stacking a lower electrode, a piezoelectric layer, and an upper electrode (not shown) on the wafer 31, respectively. Begins. This embodiment illustrates a form in which an air gap is employed as the isolation structure. That is, before stacking each layer of the FBAR 35, a process of forming a plurality of cavities on the wafer 31 and filling the sacrificial material 33 in the cavity to have a flat upper surface with the upper surface of the wafer 31. It may include a process.

In addition, connection pads 326 connected to upper and lower electrodes (not shown) are formed on the wafer 31. The connection pads 36 may be formed of Au, Al, or an alloy thereof. The connection pad 36 is formed outside the FBAR resonance region, and is formed to extend to provide a partial region of the connection pad 36 on the outer side of the protective cap structure formed later.

Next, as shown in FIG. 3B, a photoresist 37 is formed on the upper surface of the wafer 31. In the present invention, the photoresist 37 is employed to form the sidewall structure of the protective cap. In general, the photoresist 37 is not only easier to process than a silicon substrate, but also has an advantage of allowing a very precise process of the photolithography process. .

3C, the photoresist 37 is selectively etched to provide a sidewall structure 37 'surrounding the FBAR 35. As shown in FIG. The selective removal process is performed such that at least one region of the connection pad 36 is located outside the sidewall structure 37 '. After the step of forming the side wall structure 37, the desired air gap a is formed by forming a predetermined via hole v in the resonance region of the FBAR 35 and removing the sacrificial material 33 through the via hole v. . The air gap (a) forming process may be advantageously performed by performing a dry etching process using polysilicon as the sacrificial material 33 and using xenon-based gas in step 3a. In addition, after the dry etching process, an etching process may be performed on the upper electrode for tuning the resonance frequency as necessary. This tuning process can be implemented by adjusting the thickness of the upper electrode.

Next, as shown in FIG. 3D, a dry film resist (DFR) is stacked on the sidewall structure 37 ′. Since the dry film resist 38 has a certain structural stability, it may be provided as a roof of the protective cap. The dry film resist 38 may also be precisely patterned into a desired shape through a simple lithography process like the photoresist 37.

3E, the dry film resist 38 is selectively removed to form the roof structure 38 ′. Through this process, the cap structures 37 'and 38' protecting the FBAR 35 region can be obtained. The connection pads 36 are extended to be exposed to the outside of the cap structures 37 ′ and 38 ′. Thus, the exposed connection pads 36 area may be provided as a wire bonding area in a wafer-level package. have.

Next, as shown in FIG. 3F, the sidewall structure 37 ′ and the roof structure 38 ′ are hardened to complete the protection cap 39 for sealing the FBAR 35. The present curing process may be implemented by irradiating ultraviolet (UV) light on each of the structures 37 'and 38', but is not limited thereto, and an appropriate temperature when the material of the structures 37 'and 38' is a thermosetting resin. It may be implemented by heat treatment at.

Finally, the wafer level FBAR package 45 shown in FIG. 3G can be obtained by cutting the wafer 31 in units of individual FBARs 35 having the protective cap 39.

In the wafer level FBAR package 45 described in this embodiment, the protective cap 39 is formed by using the photoresist 37 and the dry film 38, so that the process is simple and precise processing is possible. However, the protective cap 39 obtained in the present embodiment has a disadvantage in that its structural stability is weaker than that of a conventional cap structure such as a silicon substrate, but the present invention provides a new duplexer package manufacturing process to compensate for this.

4A to 4D are cross-sectional views illustrating a method of manufacturing a FBAR duplexer package according to an embodiment of the present invention. The FBAR duplexer package manufacturing method according to the present invention is based on the wafer level FBAR manufacturing method described above.

The method of manufacturing the FBAR duplexer package begins with preparing the FBAR packages 45a and 45b for transmission and reception. The transmission / reception FBAR packages 45a and 45b may be wafer level FBAR packages obtained in FIGS. 3A and 3G. The wafer-level FBAR package includes FBARs 35a and 35b having piezoelectric layers and upper and lower electrodes formed on substrates 31a and 31b, respectively, connection pads 36a and 36b and connection pads 36a and 36b respectively connected to the upper and lower electrodes. And protective caps 39a and 39b formed on the substrates 31a and 31b to seal one area of the 36b to seal the FBARs 35a and 35b.

As shown in FIG. 4A, the FBAR packages 45a and 45b for transmitting and receiving are respectively die-bonded on the package substrate 41 on which the duplexing circuit pattern (not shown) is implemented. The package substrate 41 may be a PCB substrate advantageous for a package manufacturing process. In addition, as will be apparent to those skilled in the art, the present diebonding process can be readily performed using a suitable adhesive material 42.

Subsequently, as shown in FIG. 4B, wire bonding is performed to connect the exposed connection pads 36a and 36b of the FBAR packages 45a and 45b and the specific regions of the duplexing circuit pattern, respectively. Since the protective caps 39a and 39b employed in the present invention can be precisely formed so that one region of the connection pads 36a and 36b is exposed to the outside thereof, the bonding pads 36a and 36b having an appropriate area are bonded to each other. Can be provided as

Next, as shown in FIG. 4C, the preliminary resin molding 47 is formed by sealing the FBAR packages 45a and 45b for transmission and reception using an encapsulating agent. As such, the sealing process using the encapsulating agent can prevent damage or collapse of the protective caps 39a and 39b which are somewhat weak in structure by using a material having a high fluidity unlike the final EMC process. In addition, the preliminary resin molding 47 formed through the present process may compensate for the weak structural stability of the protective caps 39a and 39b.

Finally, the EMC molding part 48 is formed on the sealed FBAR packages 45a and 45b as shown in FIG. 4D. The EMC molding part 48 employed in the present invention serves as the final molding part. The molding process may be a process similar to the conventional sealing process described in FIG. 2A. Even if the pressure applied in the present molding process is somewhat large as in the prior art, the protective caps 39a and 39b may be stably maintained by the preliminary resin molding part 47 by the encapsulating agent described above.

As such, the invention is not to be limited by the foregoing embodiments and the accompanying drawings, which are intended to be limited by the appended claims. Accordingly, various forms of substitution, modification, and alteration may be made by those skilled in the art without departing from the technical spirit of the present invention described in the claims, which are also within the scope of the present invention. something to do.

As described above, according to the present invention, not only the process can be simplified by manufacturing the wafer-level FBAR package using photoresist and dry film, but also more precise processing is possible, so that further miniaturization of the FBAR package can be realized.

In addition, in adopting the package obtained in the wafer-level FBAR package manufacturing method of the present invention in the duplexer package, it is possible to compensate for the low structural stability of the protective cap of the present invention by performing a pre-molding with an encapsulant with a low application pressure. .

Claims (8)

Forming a plurality of FBARs each comprising a piezoelectric layer and an upper and lower electrodes on the wafer; Forming connection pads respectively connected to upper and lower electrodes on the wafer; Forming a photoresist on the upper surface of the wafer; Selectively removing the photoresist to form a sidewall structure surrounding each of the FBARs, wherein a region of each connection pad is exposed outside of the sidewall structure: Stacking a dry film resist on top of the sidewall structure; Selectively removing the dry film to form the roof structure; Forming a protective cap for sealing each FBAR by curing the sidewall structure and the roof structure; And A wafer level FBAR package manufacturing method comprising the step of cutting the wafer in units of individual FBAR device having the protective cap. The method of claim 1, Forming the plurality of FBAR on the wafer, Forming a plurality of cavities on the wafer, filling a sacrificial material in the cavity so as to have a flat top surface with the wafer top surface, and sequentially forming a lower electrode, a piezoelectric layer, and an upper electrode on at least the cavity region To do so, The method further comprises removing the sacrificial material using via holes. The method of claim 2, Removing the sacrificial material is performed after forming the sidewall structure and prior to laminating the dry film resist. The method of claim 3, Fabricating a wafer level FBAR package further comprising adjusting the resonant frequency of each FBAR by partially etching the upper electrode after removing the sacrificial material and before laminating the dry film resist. Way. The method of claim 1, Forming the protective cap is a wafer level FBAR package manufacturing method, characterized in that for curing the side wall structure and the roof structure using a thermal curing or UV-curing method. FBARs having piezoelectric layers and upper and lower electrodes formed on the substrate, and connection pads respectively connected to the upper and lower electrodes, and protective caps formed on the substrate to seal one region of the connection pads outside thereof, respectively. Providing a FBAR package for transmitting and receiving; Die bonding each of the transmit and receive FBAR packages on a package substrate on which a duplexing circuit is implemented; Wire bonding each of the connection pad regions of the FBAR package for transmission and reception to be connected to a designated region of the duplexing circuit pattern; And Forming a preliminary resin molding part on an outer side of a protective cap of the FBAR package for transmitting and receiving using an encapsulating agent; And And forming an EMC molding part on the FBAR package for transmitting and receiving sealed in the resin molding part. The method of claim 6, Preparing the FBAR package for transmitting and receiving each, Forming a plurality of FBARs having a piezoelectric layer and upper and lower electrodes on a wafer, forming connection pads respectively connected to upper and lower electrodes on the wafer, forming a photoresist on the upper surface of the wafer, and Selectively removing the resist to form a sidewall structure surrounding each FBAR, wherein a region of each connection pad is exposed outside of the sidewall structure; and laminating a dry film resist on top of the sidewall structure; Selectively removing the dry film resist to form the roof structure, forming a protective cap for sealing each FBAR by curing the sidewall structure and the roof structure, and having the individual protective caps. FBAR duplex characterized in that the step of cutting the wafer in units of FBAR device Package method. The method of claim 6, The package substrate is a printed circuit board (PCB) characterized in that the FBAR duplexer package manufacturing method.

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