KR100518828B1 - MEMS structure for metal interconnection and fabrication method thereof - Google Patents

Abstract

Disclosed is a method of manufacturing a MEMS structure for forming an electrical connection line between devices. The manufacturing method includes depositing a seed layer on the entire upper surface of the substrate, forming a metal thin film by plating a first metal on the entire upper surface of the seed layer, and etching a predetermined region of the substrate under the seed layer to at least Manufacturing a through hole, plating a second metal in each through hole, manufacturing a metal connection line electrically connecting the devices on both sides of the substrate, and removing the seed layer and the metal thin film. It includes. Accordingly, it is possible to manufacture a MEMS structure in which a metal connection line is formed without voids and gaps.

Description

MEMS structure used as interconnection line between devices and manufacturing method thereof MEMS structure for metal interconnection and fabrication method

The present invention relates to a micro electro-mechanical system (hereinafter referred to as "MEMS") structure and a manufacturing method thereof, and more particularly, to a MEMS structure for electrically connecting external elements on both sides of a substrate and a method for manufacturing the same. will be.

MEMS stands for Micro Electro-Mechanical System, and refers to a technology or processed product that processes a micromechanical structure using a semiconductor processing method. In this regard, the design of machinery and equipment with ultra-fine structures of several micrometers or less is expected to bring about tremendous changes in all industries including electronics, machinery, medical, and defense. Is nurturing.

In particular, in the electronic field, MEMS technology may be used to develop ultra-small and ultra-light products such as mobile phones. That is, a piezoelectric thin film resonator manufactured by using MEMS technology (Film Bulk Acoustic Resonator: referred to as "FBAR") can be used as a filter and duplexer.

FBAR can be mass-produced with minimal cost and has the advantage of being implemented in the smallest size. In addition, it is possible to realize a high quality factor (Q) value, which is the main characteristic of the filter, and to be used in the micro frequency band, and particularly to the personal communication system (PCS) and digital cordless system (DCS) bands. It has the advantage of being able to.

In general, the FBAR device is implemented by sequentially stacking a lower electrode, a piezoelectric layer, and an upper electrode on a substrate. The operation principle is to apply electric energy to the electrode to induce an electric field that changes in time in the piezoelectric layer, and this electric field causes a resonance in the piezoelectric layer by inducing the acoustic wave in the same direction as the vibration direction of the laminated resonance part. To generate.

On the other hand, when manufacturing such a MEMS structure, such as FBAR, it is possible to further reduce the size by concentrating several devices on one substrate to implement as a single chip. In this case, by fabricating a metal line (electric line) that electrically connects each device with the external electrode terminal, each device can be made to operate by applying an electric field.

Figure 1 shows a capacitor and focused FBAR as an example of such a MEMS structure. According to the drawing, the air gap type FBAR 10 and the external electrode terminal 20 are electrically connected to the MEMS structure 100. In the drawing, the MEMS structure is composed of a substrate 110 and a metal connection line 150 penetrating through the substrate, and the FBAR 10 includes the lower electrode 11, the piezoelectric layer 12, and the upper electrode 13 in turn. In the stacked state, the substrate 110 is spaced apart from the predetermined distance to have an air gap. Meanwhile, a separate metal layer 14 is disposed on the substrate 110 in the air gap to serve as a capacitor together with the lower electrode 11.

In the drawing, when an electric field is applied to the external terminals 20a and 20c on both sides, an electric field is applied to the upper and lower electrodes 13 and 11 of the FBAR 10 through the metal connection line 150. When an electric field is applied to the upper and lower electrodes 13 and 11, the piezoelectric layer 12 positioned therebetween causes a piezoelectric phenomenon to resonate.

At this time, when an electric field is applied to the intermediate external terminal 20b, an electric field is applied to the metal layer 14 deposited on the substrate 110 to operate as a capacitor together with the lower electrode 11.

On the other hand, Figure 2 is a cross-sectional view showing a conventional manufacturing method for the portion of the MEMS structure 100 forming the connection with the external electrodes (20a, 20b, 20c) in the FBAR manufacturing process.

First, a photoresist film is deposited on a conventional silicon substrate 51, and then a predetermined portion of the substrate 51 is etched to produce several through holes 52 (FIG. 2A). And (b)).

Next, the seed layer 53 is deposited on the inside of the through hole 52 and on the entire surface of the substrate 51 (FIG. 2C). The seed layer 53 is used for plating in a step to be described later, and preferably, chromium (Cr) and / or gold (Au) may be used as the seed layer 53, but is not limited thereto.

Next, plating is performed on the seed layer 53 using a copper (Cu) plate to fill the inside of the through hole 52 (FIG. 2 (d)). Finally, after removing the plating portion formed on the upper and lower substrates by using the CMP process, the structure as shown in (e) of FIG. 2 is finally completed. As shown in the figure, each of the through holes 52 is filled with the plating 54 to electrically connect the upper and lower portions of the substrate. Thus, the plating method on the uneven | corrugated board | substrate is called the damascene method.

However, when plating by such damascene method, the plating method is complicated and precise control is difficult, and the plating speed in each seed layer (seed layer on the upper substrate and seed layer inside the through hole is different, respectively, FIG. 2). As shown in (d) and (e) of the through-hole, the gap 52 is slightly filled up, or the metal connection line 54 inside the through-hole 52 is connected to each other at a predetermined portion of the void. 52a) can also be formed.

When the voids 52a are generated, impurities inside the voids may rust and cause a malfunction of the device, or may be damaged by being heated by an external applied current. On the other hand, in the case where the gap 52 is formed, fine dust or the like is introduced from the outside and enters the inside of the device, thereby causing a malfunction of the device.

In addition, there is a problem that the process is complicated in that the CMP process is used.

SUMMARY OF THE INVENTION The present invention has been made to solve this problem, and an object of the present invention is to provide a MEMS structure in which a metal connection line is completely filled without voids and gaps, and a manufacturing method thereof.

Method of manufacturing a MEMS structure according to the present invention, (a) depositing a seed layer (seed layer) on the entire upper surface of the substrate, (b) plating a first metal on the upper surface of the seed layer to produce a metal thin film (C) etching at least a predetermined area of the substrate under the seed layer to produce at least one through hole; (d) an external element connected to upper and lower surfaces of the substrate by plating a second metal in the at least one through hole; Producing a metal connection line for electrically connecting a, and (e) removing the seed layer and the metal thin film.

In this case, step (a) may further facilitate the removal of the metal thin film by further comprising the step of coating a release agent on the seed layer.

On the other hand, according to another embodiment of the present invention, etching a predetermined region of the upper surface of the substrate to produce at least one trench (trench), depositing a seed layer on the trench and the upper surface of the substrate, the seed layer Plating a first metal on the substrate, etching a substrate positioned below the at least one trench, plating a second metal in the etched substrate region, and present on the trench of the first metal Provided is a method of manufacturing a MEMS structure, including the step of manufacturing a metal connection line by etching the remaining portion leaving only a portion thereof.

The MEMS structure manufactured by this method includes a substrate having at least one through hole penetrating a predetermined region, and a metal connecting line filled in the at least one through hole, wherein the metal connecting line is formed on upper and lower surfaces of the substrate. When an external device is connected to the device, the device serves to electrically connect each device.

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

3 is a diagram illustrating a method of manufacturing the MEMS structure 100 of FIG. 1 according to one embodiment of the present invention. According to the drawing, first, the seed layer 120 is deposited on the entire surface of the upper surface of the substrate 110 (FIG. 3A). The substrate 110 may use a conventional silicon substrate, and the seed layer 120 may also use chromium, gold, or the like as described above. In addition, the seed layer 120 may be deposited using a thermal evaporator.

Next, the first metal is electroplated on the seed layer 120 to prepare a metal thin film 130 (FIG. 3B). As the first metal, a Cu plate may be used. The metal thin film 130 is a portion that serves as a support to prevent the seed layer 120 from being warped or torn during the etching of the substrate 110.

Next, a predetermined portion of the lower substrate 110 is etched to form at least one through hole 140 (FIG. 3C). In this case, the etching method may be any one of a wet etching method and a dry etching method. The wet etching method is a method of etching using a chemical solution such as acetic acid solution, hydrofluoric acid, aqueous solution of phosphate, etc., and the dry etching method is a method of etching using gas, plasma, ion beam, etc. to be.

Then, the metal connection line 150 is manufactured by filling the second metal into the formed through hole 140 (FIG. 3 (d)). In this case, the seed layer 120 and the metal thin film 130 play a role in forming the metal connection line 150. Meanwhile, the first metal and the second metal are classified for convenience of description, but may substantially use the same material (for example, Cu).

Finally, after etching the seed layer 120 and the metal thin film 130, the MEMS structure 100 having at least one metal connection line 150 connecting the upper and lower substrates 110 is completed (see FIG. 3). (e)). There may be various methods of etching the metal thin film 130, but it is preferable to simply remove the metal thin film 130 using a release agent. That is, when the release agent (not shown) is applied on the seed layer 120 in the step before plating the metal thin film 130, the metal thin film 130 may be easily removed.

According to this, since the metal connection line 150 is manufactured using a metal filling method unlike the conventional damascene method, the void 52a and the gap 52 shown in FIG. 2 are less likely to be formed. . When the gap 52 is formed, there is a possibility that the fine dust flows in as described above, or the moisture may enter the device, and according to the present invention, by completely filling the through hole so that such a gap does not occur, the hermetic ) Can be made.

Looking at the final fabricated MEMS structure, the metal connecting line 150 penetrating the upper and lower substrates on a predetermined region of the substrate is configured. Devices focused on the upper and lower substrates with the metal connection line 150 interposed therebetween are electrically connected to each other.

Figure 4 illustrates step by step the method of manufacturing a MEMS structure presented as another embodiment of the present invention.

According to the drawing, first, a predetermined region on the substrate 200 is etched to fabricate a trench 200a (FIG. 4A). The trench 200a is fabricated in a portion to form a metal connection line in a step to be described later.

Next, the seed layer 210 is deposited on the entire surface of the upper surface of the trench 200a and the substrate 200 (FIG. 4B). The material and deposition method of the seed layer 210 are as described above.

Then, the metal is plated using the seed layer 210 as a medium to cover the entire surface of the trench 200a and the upper surface of the substrate 200 (FIG. 4C).

Next, the through hole 200b is formed by etching the substrate 200 under the trench 200a (d in FIG. 4). In the drawing, although the seed layer 210 in the trench 200a is illustrated as being etched, the seed layer 210 itself is a conductive material, and thus it is not necessarily etched. When the seed layer 210 is etched, when the metal is filled in the step described later, the upper metal part 220 serves as a seed.

After the etching region 200b in the substrate 200 is filled with the metal 220 again and the upper metal 220 is removed, a structure as shown in FIG. 4E is finally completed. Looking at the drawing, it can be seen that has the same structure as in (e) of FIG. 3 except for the seed layer 210.

According to the embodiment shown in FIG. 4, by plating the metal connection line 220 on both sides of the substrate 200, the possibility of the void 52a and the gap 52 is reduced more than in the embodiment of FIG. 3.

According to the manufacturing method of FIGS. 3 and 4, in the MEMS device as shown in FIG. 1, a structure for forming an electrical connection between the devices may be manufactured.

As described above, according to the present invention, a MEMS structure used when a plurality of MEMS devices are focused or when connecting an external electrode terminal and the MEMS device can be manufactured by a simple method. In addition, it is possible to reduce the possibility of the voids and gaps generated during the manufacturing of the MEMS structure, there is an effect that can increase the stability of the structure.

In addition, although the preferred embodiment of the present invention has been shown and described above, the present invention is not limited to the specific embodiments described above, but the technical field to which the invention belongs without departing from the spirit of the invention claimed in the claims. Of course, various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or the prospect of the present invention.

1 is a cross-sectional view of a FBAR (Film Bulk Acoustic Resonator) using a micro electromechanical systems (MEMS) structure connecting the devices on both sides of the substrate

2 is a step-by-step process diagram for a conventional method of manufacturing the MEMS structure of FIG.

3 is a step-by-step process diagram for the method of manufacturing the MEMS structure of FIG. 1 according to the present invention, and

Figure 4 is a step-by-step process diagram for the MEMS structure manufacturing method presented as an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

110, 200: substrate 120, 210: seed layer

130: metal thin film 150, 220: metal connection line

Claims (4)

(a) depositing a seed layer over the entire top surface of the substrate; (b) manufacturing a metal thin film by plating a first metal on the entire upper surface of the seed layer; (c) fabricating at least one through hole by etching a predetermined region of the substrate under the seed layer; (d) plating a second metal in the at least one through hole to manufacture a metal connection line electrically connecting external elements connected to upper and lower surfaces of the substrate; and (E) removing the seed layer and the metal thin film; MEMS structure manufacturing method comprising a. The method of claim 1, In step (a), Coating a release agent on the seed layer; MEMS structure manufacturing method characterized in that it further comprises. Etching at least a portion of the substrate upper surface to fabricate at least one trench; and Depositing a seed layer on the trench and the top surface of the substrate; Plating a first metal on the seed layer; Etching the substrate under the at least one trench; Plating a second metal into the etched substrate region; and Manufacturing a metal connection line by etching a remaining portion of the first metal while leaving only a portion present on the trench. delete