KR100488491B1 - Film Bulk Acoustic Resonator and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a film bulk acoustic wave resonator and a method of manufacturing the same. Aluminum can be used as the upper and lower electrodes, thereby reducing a target cost, and allowing the upper and lower electrodes and the piezoelectric layer to have the same chamber. In order to maximize the productivity as well as to be deposited in the same etchant, the plate-shaped semiconductor substrate, the lower electrode of aluminum (Al) deposited on the upper surface of the semiconductor substrate, and the lower electrode And a piezoelectric layer made of aluminum nitride (AlN) material deposited to a predetermined thickness on an upper surface thereof, and an upper electrode made of aluminum (Al) deposited on an upper surface of the piezoelectric layer.

Description

Film bulk acoustic wave resonator and its manufacturing method {Film Bulk Acoustic Resonator and manufacturing method

The present invention relates to a film bulk acoustic wave resonator and a method of manufacturing the same, and more specifically, it is possible to use aluminum as the upper and lower electrodes, thereby reducing the target cost, and reducing the upper and lower electrodes and the piezoelectric layer. The present invention relates to a film bulk acoustic wave resonator and a method of manufacturing the same, which can be deposited in the same chamber as well as etched with the same etchant to maximize productivity.

In general, a film bulk acoustic acoustic resonator (FBAR) is a filter using elastic waves of the piezoelectric layer according to frequency. The size of a traditional frequency filter was equal to the wavelength of the electromagnetic wave in its frequency band. Therefore, the size of the filter using the electromagnetic wave is relatively large. For example, when the frequency of the electromagnetic wave is 1 GHz, the size of the classical filter is about 30 cm and about 1 mm at 300 GHz. However, when the elastic wave of the piezoelectric layer is used, the wavelength of the elastic wave is reduced to 1 / 10,000 as compared with the wavelength of the electromagnetic wave. Accordingly, the piezoelectric layer converts electromagnetic waves into elastic waves, and the size thereof becomes smaller by the wavelength of the elastic waves. In other words, its size is about several hundred microns, and it can be fabricated from a wafer, which makes it possible to manufacture a large amount of devices in a batch.

1A-1C, examples of conventional film bulk acoustic wave resonators 101 ', 102', 103 'are shown.

First, shown in FIG. 1A is a film bulk acoustic wave resonator 101 'manufactured by a bulk micromachining method, and a configuration of the film bulk acoustic wave resonator 101' is cut at a lower portion by a body microfabrication at a lower portion thereof, whereby a predetermined cavity 112 'is formed. Of the formed silicon (Si) or gallium arsenide (GaAs) semiconductor substrate 110 ', the film 120' covering the cavity 112 'as an upper surface of the semiconductor substrate 110', and the film 120 ' A lower electrode 130 'deposited on an upper surface, a piezoelectric layer 140' deposited on an upper surface of the lower electrode 130 ', and an upper electrode 150' deposited on an upper surface of the piezoelectric layer 140 '. have.

This has the disadvantage that the substrate 110 'needs to be immersed in the etching solution for a long time in order to form a constant cavity 112' in the substrate 110 'during the manufacturing process. There is also a big disadvantage in the risk of breakage when separating into semiconductor chips.

In order to solve this problem, there is a film bulk acoustic wave resonator 102 'manufactured by Surface Micromachining as shown in FIG. 1B, which is composed of a semiconductor substrate having an air gap 113' formed thereon. 110 '), the lower electrode 130' positioned above the air gap 113 'of the substrate 110', the piezoelectric layer 140 'deposited on the upper surface of the lower electrode 130', and the piezoelectric element. The upper electrode 150 'is deposited on the upper surface of the layer 140'.

This is because there is no cavity 112 'itself, so that the chip is not easily broken when the semiconductor chip is separated, and the area of the air gap 113' is not increased, thereby increasing the number of semiconductor chips per wafer. However, such a structure has a disadvantage in that it is very difficult to control stress of various films positioned on the air gap 113 ′, that is, the lower electrode 130 ′, the piezoelectric layer 140 ′, and the like, and the actual yield is low.

In order to solve this problem and greatly improve the device characteristics, there is a film bulk acoustic wave resonator 103 'implemented using an acoustic wave reflecting layer 115' called Bragg Reflector as shown in FIG. 1C. Its structure includes a semiconductor substrate 110 ', an acoustic wave reflecting layer 115' deposited on the substrate 110 ', a lower electrode 130' on which an acoustic wave reflecting layer 115 'is deposited on the upper surface, and a lower portion thereof. The piezoelectric layer 140 ′ deposited on the electrode 130 ′ and the upper electrode 150 ′ deposited on the upper surface of the piezoelectric layer 140 ′ are formed. Here, the acoustic wave reflecting layer 115 ′ is a layer formed by sequentially depositing an oxide film SiO 2, tungsten W, and the like on the surface of the semiconductor substrate 110 ′.

In the piezoelectric layer, aluminum nitride (AlN) or zinc oxide (ZnO) is mainly used. Since the electromechanical coefficient (K2) of the aluminum nitride (AlN) is better, mainly aluminum nitride is a piezoelectric material. It is mainly used as a layer. In addition, the lower electrode and the upper electrode formed on the lower and upper portions of the piezoelectric layer may be the best using aluminum (Al) used in a conventional semiconductor manufacturing process, but the aluminum nitride (AlN) and aluminum (Al) may be the same. Since it reacts with a crate, expensive molybdenum (Mo), chromium (Cr), or tungsten (W) with a good selection ratio is mainly used. All these lower electrodes, piezoelectric layers and upper electrodes are formed by conventional RF magnetron sputtering.

However, such a conventional film bulk acoustic wave resonator has the following problems in structure or manufacturing process.

First, the lower electrode and the upper electrode are formed of a piezoelectric layer (aluminum nitride (AlN)) and expensive molybdenum (Mo), chromium (Cr) or tungsten (W) with good selectivity, thereby forming a target for forming the electrode. There is a disadvantage of increasing cost.

Second, since the physical properties of the lower electrode, the upper electrode, and the piezoelectric layer are completely different, the deposition process must be performed in different chambers, and thus, the process becomes complicated and the contamination probability is high, resulting in a decrease in productivity.

Third, since the etchant of the lower electrode, the upper electrode and the piezoelectric layer is completely different, there is a problem that it is inconvenient to control a plurality of etchant, and there is a problem that the productivity is lowered due to the high probability of contamination.

Therefore, the present invention has been made to solve the conventional problems as described above, the object of the present invention can use aluminum as the upper and lower electrodes can reduce the target cost (target cost), the upper and lower electrodes and The present invention provides a film bulk acoustic wave resonator capable of maximizing productivity by depositing piezoelectric layers in the same chamber as well as etching with the same etchant and a method of manufacturing the same.

In order to achieve the above object, the film bulk acoustic wave resonator according to the present invention has a plate-shaped semiconductor substrate, a lower electrode made of aluminum (Al) deposited on the upper surface of the semiconductor substrate, and a predetermined thickness on the upper surface of the lower electrode. A piezoelectric layer made of aluminum nitride (AlN) material, and an upper electrode made of aluminum (Al) material deposited on the upper surface of the piezoelectric layer.

Here, only a predetermined region of the lower electrode and the piezoelectric layer may be bonded to each other, and the remaining regions may be separated from each other by a silicon oxide film.

In order to achieve the above object, a method of manufacturing a film bulk acoustic wave resonator according to the present invention includes the steps of depositing aluminum (Al) with a predetermined thickness on an upper surface of a plate-shaped semiconductor substrate, and etching a predetermined shape to form a lower electrode; Forming a silicon oxide film having a predetermined thickness on the lower electrode and an outer surface of the semiconductor substrate, etching a predetermined region of the silicon oxide film to expose the lower electrode to the outside, and lowering the exposed externally Depositing aluminum nitride (AlN) at a predetermined thickness on the upper surface of the electrode and the silicon oxide film, etching to a predetermined shape to form a piezoelectric layer, and depositing aluminum (Al) at a predetermined thickness on the surfaces of the piezoelectric layer and the oxide film. And forming an upper electrode by etching in a predetermined form.

Here, the lower electrode, the piezoelectric layer and the upper electrode may be deposited in the same chamber.

In addition, the lower electrode, the piezoelectric layer, and the upper electrode may be etched with the same etchant.

As described above, according to the film bulk acoustic wave resonator according to the present invention and a method of manufacturing the same, the lower electrode and the upper electrode can be deposited using an aluminum target (Al target) commonly used in the semiconductor manufacturing process, thereby providing a target cost. (target cost) has the advantage that can be significantly reduced.

In addition, since both the lower electrode, the upper electrode, and the piezoelectric layer include aluminum, the lower electrode, the upper electrode, and the piezoelectric layer may be continuously deposited in one chamber, thereby improving productivity. .

In addition, since the etchant of the lower electrode, the upper electrode and the piezoelectric layer is the same, it is easy to control the process for one etchant, and there is an advantage that productivity is improved due to a low probability of contamination.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

2A, a cross-sectional view of a film bulk acoustic wave resonator 101 according to an embodiment of the present invention is shown. Referring to FIG. 2B, a film bulk acoustic wave resonator 102 according to another embodiment of the present invention is shown. A cross-sectional view is shown and referring to FIG. 2C, there is shown a cross-sectional view of a film bulk acoustic wave resonator 103 according to another embodiment of the present invention.

As shown in FIG. 2A, the film bulk acoustic wave resonator 101 according to an exemplary embodiment of the present invention may be formed on the upper surface of the semiconductor substrate 110 and the semiconductor substrate 110 of silicon (Si) or gallium arsenide (GaAs). The insulating film 120 formed through the lower electrode 130 formed of the aluminum (Al) material formed on the upper surface of the insulating film 120, the silicon oxide film 160 formed on the lower electrode 130 and the silicon oxide film 160 A piezoelectric layer 140 made of aluminum nitride (AlN) material connected to and deposited on an upper surface of the electrode 130, and an upper electrode 150 made of aluminum (Al) formed on an upper surface of the piezoelectric layer 140.

Of course, a cavity 112 of a predetermined space may be formed in the semiconductor substrate 110 to maximize resonance characteristics.

Subsequently, as shown in FIG. 2B, the film bulk acoustic wave resonator 102 according to another embodiment of the present invention is similar to that shown in FIG. 2A, and therefore only the differences will be described.

As shown, in the film bulk acoustic wave resonator 102 according to the present invention, an air gap 113 having a predetermined depth is formed below the lower electrode 130 instead of the cavity 112 that is difficult to process in the semiconductor substrate 110. have. The air gap 113 is formed by etching a sacrificial layer (not shown) as is well known, and serves to improve the characteristics of the piezoelectric layer 140. Of course, both the lower electrode 130 and the upper electrode 150 are formed of aluminum as described above, and the piezoelectric layer 140 is formed of aluminum nitride (AlN). In addition, only a predetermined region of the lower electrode 130 and the piezoelectric layer 140 are bonded to each other, and a silicon oxide layer 160 having a predetermined thickness is formed between the remaining regions.

As shown in FIG. 2C, the film bulk acoustic wave resonator 103 according to another embodiment of the present invention is also similar to that shown in FIG. 2B, and only the differences will be described.

As shown, no cavity 112 or air gap 113 is formed in the semiconductor substrate 110, but the multilayer acoustic wave reflecting layer 115 is formed between the lower electrode 130 and the semiconductor substrate 110. Is further formed. The acoustic wave reflecting layer 115 may be formed by sequentially stacking an oxide film (SiO 2) and tungsten (W), which serves to improve characteristics of the piezoelectric layer 140. Of course, the lower electrode 130 and the upper electrode 150 are made of aluminum, and the piezoelectric layer 140 is made of aluminum nitride (AlN). In addition, only a predetermined region of the lower electrode 130 and the piezoelectric layer 140 are bonded to each other, and a silicon oxide layer 160 having a predetermined thickness is formed between the remaining regions.

3A to 3G, a method of manufacturing a film bulk acoustic wave resonator according to the present invention is shown.

As shown, the method of manufacturing the film bulk acoustic wave resonator according to the present invention includes forming a lower electrode 130 on the upper surface of the semiconductor substrate 110 (FIG. 3A), and forming a silicon oxide film 160 on the lower electrode 130. Forming (FIG. 3B), etching a predetermined region of the silicon oxide film 160 (FIG. 3C), and forming a piezoelectric layer 140 on the lower electrode 130 and the silicon oxide film 160 (FIG. 3D). Etching and removing a predetermined region of the piezoelectric layer 140 (FIG. 3E), forming an upper electrode 150 on the piezoelectric layer 140 (FIG. 3F), and forming the upper electrode 150 in a predetermined form. It consists of the step of etching (Fig. 3g).

First, the forming of the lower electrode 130 on the upper surface of the semiconductor substrate 110 includes preparing a conventional silicon (Si) or gallium arsenide (GaAs) semiconductor substrate 110 and the semiconductor substrate 110. And depositing aluminum (Al) on the upper surface with a predetermined thickness, and forming a lower electrode 130 by etching a predetermined shape using a photoresist (not shown) as a mask (see FIG. 3A).

Of course, although not shown in the semiconductor substrate 110, a cavity 112 may be formed, a sacrificial layer may be formed to form an air gap 113, or an acoustic wave reflecting layer 115 may be formed.

The step of forming the silicon oxide film 160 on the lower electrode 130 is performed by forming a silicon oxide film 160 having a predetermined thickness on the upper surface of the lower electrode 130 and the outer semiconductor substrate 110 (see FIG. 3B).

Of course, a silicon nitride film may be formed instead of the silicon oxide film, and the silicon oxide film is not limited in the present invention.

In the etching of a predetermined region of the silicon oxide layer 160, a photoresist (not shown) is formed to open a predetermined region of the silicon oxide layer 160, and then the open silicon oxide layer ( 160 is removed, and an etching stop is performed on the upper surface of the lower electrode 130 exposed through the silicon oxide layer 160 (see FIG. 3C).

The piezoelectric layer 140 may be formed on the lower electrode 130 and the silicon oxide layer 160 by depositing aluminum nitride (AlN) on the lower electrode 130 and the silicon oxide layer 160 exposed to a predetermined thickness. (See FIG. 3D).

Here, since both the lower electrode 130 and the piezoelectric layer 140 include aluminum, the deposition process may be performed in the same chamber.

Etching and removing a predetermined region of the piezoelectric layer 140 may include forming a photoresist (not shown) on a surface of the piezoelectric layer 140 so that the predetermined region of the piezoelectric layer 140 is opened, and then using the etchant to open the piezoelectric layer. This is done by removing layer 140 (see Figure 3e).

Since the lower electrode 130 is separated from the silicon oxide layer 160, the same etchant used for etching the lower electrode 130 may be used for etching the piezoelectric layer 140.

The forming of the upper electrode 150 on the piezoelectric layer 140 is performed by depositing aluminum (Al) with a predetermined thickness on the surfaces of the piezoelectric layer 140 and the oxide film 160 (see FIG. 3F).

Similarly, since the upper electrode 150 also includes aluminum like the piezoelectric layer 140 or the lower electrode 130, the upper electrode 150 may be formed using the aluminum target in the same chamber.

Finally, the step of etching the upper electrode 150 in a predetermined form, after the photoresist (not shown) is applied to the upper electrode 150 and the silicon oxide film 160 in a predetermined pattern, the lower electrode 130 and This is done by etching the upper electrode 150 of the unnecessary portion using the same etchant used for etching the piezoelectric layer 140 (see Fig. 3G).

Through this process, the manufacturing of the film bulk acoustic wave resonator according to the present invention is completed, which may use the same etchant during etching of the lower electrode 130, the piezoelectric layer 140, and the upper electrode 150, and also the lower electrode. The deposition of the 130, the piezoelectric layer 140, and the upper electrode 150 may be performed in the same chamber.

As described above, the present invention has been described with reference to the above embodiments, but the present invention is not limited thereto, and various modified embodiments may be possible without departing from the scope and spirit of the present invention.

Therefore, according to the film bulk acoustic wave resonator and a method of manufacturing the same, the lower electrode and the upper electrode can be deposited using an aluminum target which is commonly used in a semiconductor manufacturing process, thereby providing a target cost. There is an effect that can be significantly reduced.

In addition, since the lower electrode, the upper electrode, and the piezoelectric layer both contain aluminum, the lower electrode, the upper electrode, and the piezoelectric layer can be continuously deposited in one chamber, thereby improving productivity. .

In addition, since the etchant of the lower electrode, the upper electrode and the piezoelectric layer is the same, it is easy to control the process for one etchant, and the contamination probability is low, thereby improving productivity.

1A to 1C are cross-sectional views showing examples of a conventional film bulk acoustic wave resonator.

2A to 2C are cross-sectional views showing examples of a film bulk acoustic wave resonator according to the present invention.

3A to 3G are sequential explanatory diagrams showing a method for manufacturing a film bulk acoustic wave resonator according to the present invention.

Description of the main symbols in the drawings

101,102,103; Film bulk acoustic wave resonator according to the present invention

110; Semiconductor substrate

112; Cavity 113; Air gap

115; An acoustic wave reflecting layer 120; film

130; Lower electrode 140; Piezoelectric layer

150; Upper electrode 160; Silicon oxide

Claims (5)

(Corrected) semiconductor substrate; A lower electrode made of aluminum (Al) deposited on the upper surface of the semiconductor substrate with a predetermined thickness; A silicon oxide film deposited on upper and side surfaces of the lower electrode, the predetermined area of the upper surface of the lower electrode being opened upward; A piezoelectric layer made of aluminum nitride (AlN) material deposited on the silicon oxide film to a predetermined thickness, but also deposited on the lower electrode opened through the silicon oxide film; And, The film bulk acoustic wave resonator including an upper electrode of aluminum (Al) deposited on the upper surface of the piezoelectric layer. delete Depositing aluminum (Al) with a predetermined thickness on the upper surface of the (correction) plate-shaped semiconductor substrate, and etching the aluminum substrate to form a lower electrode; Forming a silicon oxide film having a predetermined thickness on an upper surface of the lower electrode and an outside of the semiconductor substrate; Etching a region of the silicon oxide layer to expose the lower electrode to the outside; Depositing aluminum nitride (AlN) with a predetermined thickness on the upper surface of the lower electrode and the silicon oxide film exposed to the outside, and etching the aluminum etchant to form a piezoelectric layer; And, And depositing aluminum (Al) with a predetermined thickness on the surfaces of the piezoelectric layer and the oxide film, and etching the aluminum with an etchant to form an upper electrode. The method of claim 3, wherein the lower electrode, the piezoelectric layer, and the upper electrode are deposited in the same chamber. delete