JP2008119818A - Mems device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an MEMS device having an excellent operating characteristic by reducing an electric resistance while retaining a mechanical characteristic of a structural body and its manufacturing method. <P>SOLUTION: This MEMS device has a fixed electrode 50 made of silicon formed on a silicon substrate 41, a movable electrode 60 made of silicon arranged in a mechanically movable state by providing a clearance with a nitride film 4 formed on the silicon substrate 41 and a wiring laminated part on which a first layer insulating film 52, a first wiring layer 63, a second layer insulating film 53, a second wiring layer 64 and a protective film 59 formed in the circumference of the movable electrode 60 and to cover a part of the fixed electrode 50 are laminated in this order. The movable electrode 60 is silicified by high melting point metal such as tungsten or molybdenum, etc. and a silicide part 65 is formed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a MEMS device provided with a structure such as a movable electrode and a fixed electrode formed on a silicon substrate using a semiconductor manufacturing process, and a manufacturing method thereof.

  Accompanying the progress of microfabrication technology, electromechanical devices having a minute structure such as a movable electrode and a fixed electrode formed by using a semiconductor manufacturing process, for example, so-called MEMS such as a resonator, a filter, a sensor, and a motor (Micro Electro Mechanical System) devices are attracting attention. Since MEMS devices are manufactured using a semiconductor manufacturing process, for example, it is possible to form a composite MEMS device of CMOS (Complementary Metal Oxide Semiconductor) and MEMS. It is also expected as a device that can meet the demand for higher functionality.

  Along with such demands for higher functionality of electronic devices, MEMS devices require precise current value control and electrical speedup, and the structure and wiring that constitute the circuit of the MEMS device are further increased. Low resistance is required. For example, a MEMS device handled in a high frequency band such as RF (Radio Frequency) -MEMS for wireless communication is directly connected to deterioration of the characteristics itself when the insertion loss is large, and therefore the resistance value of the entire circuit of the MEMS device is suppressed as much as possible. There is a need.

  An example of a method for manufacturing a MEMS device will be described. First, a fixed electrode and a movable electrode partially formed on a sacrificial layer are formed on a semiconductor substrate such as silicon (Si). And the wiring lamination | stacking part containing wiring is formed on a movable electrode. Then, a part of the wiring laminated portion and the sacrificial layer is removed by etching (release etching) to release the movable electrode, thereby forming the movable electrode in a mechanically movable state.

By the way, the wiring in the circuit of the MEMS device is generally patterned after depositing a metal such as aluminum (Al) by sputtering, CVD (Chemical Vapor Deposition), or vacuum deposition, as in normal semiconductor manufacturing. As a result, the resistance is low. On the other hand, structures such as movable electrodes and fixed electrodes of MEMS devices need to be subjected to some process for reducing the resistance of silicon, which is a semiconductor, after silicon is deposited and patterned. . As a processing method for reducing the resistance of a structure made of silicon, a method of forming a diffusion layer by implanting impurity ions such as phosphorus ions (for example, ³¹ P ⁺ ) into a silicon film is known (for example, (See Patent Document 1).

As a method for further reducing the resistance of the structure, for example, in Patent Document 1 and Patent Document 2, a metal is deposited on a silicon film by sputtering, CVD, vacuum deposition, or the like, and then annealed at a high temperature. Thus, a so-called silicidation method in which silicon in contact with metal titanium is diffused and alloyed is shown. For example, a silicide portion (TiSi) silicided by titanium (Ti) has a specific resistance of about 10 ⁻⁵ Ωcm, and this value is about 1/100 of the diffusion layer formed by impurity ion implantation.

Japanese Patent Application Laid-Open No. 2004-221853 JP 2001-264677 A

  As described above, in the method of forming a diffusion layer by implanting impurity ions into a structure made of silicon, the resistance value of the structure is reduced to a resistance value required for a MEMS device handled in a high frequency band. Is difficult. On the other hand, the method of siliciding a structure made of silicon is an effective method for greatly reducing the resistance of the structure, but depending on the type of metal for silicide, part of the wiring stack and part of the sacrificial layer When the movable electrode is released by etching, the silicide portion may be dissolved in the etching solution. When the silicide portion is dissolved, the resistance value increases on the contrary, or the mechanical strength is decreased due to the thinning of the structure, thereby changing the electrical and mechanical characteristics of the MEMS device. This causes a problem that desired characteristics cannot be obtained.

  The present invention has been made in view of the above, and an object of the present invention is to reduce the electrical resistance value while maintaining the mechanical characteristics of the structure, and to provide a MEMS device having excellent operating characteristics, and a method for manufacturing the same. Is to provide.

  In order to solve the above problems, a MEMS device according to the present invention includes a fixed electrode made of silicon formed on a semiconductor substrate, and a movable electrode made of silicon disposed in a mechanically movable state with a gap from the semiconductor substrate. An electrode and a wiring laminated portion formed around the movable electrode and covering a part of the fixed electrode, the wiring laminated portion including the wiring, at least the movable electrode being a refractory metal It is characterized by silicidation.

  According to this configuration, at least the movable electrode is silicided with the refractory metal in the structure made of silicon such as the fixed electrode and the movable electrode of the MEMS device. Silicided silicon can have a specific resistance of about 1/100 as compared with the case where impurities such as conventional phosphorus ions are ion-implanted, and the resistance value can be greatly reduced. Also, the silicide portion of silicon silicided with a refractory metal is difficult to dissolve in, for example, a hydrogen fluoride-based release etching solution. As a result, it is possible to prevent the resistance value from increasing and the mechanical strength from being deteriorated due to the dissolution of the silicide portion of the movable electrode. Accordingly, the resistance value of the entire circuit of the MEMS device can be greatly reduced, and the insertion loss and the passing characteristic when the MEMS device is operated can be improved. Therefore, the MEMS device having excellent operating characteristics applicable to a high frequency device or the like. Can be provided.

  In the MEMS device of the present invention, it is preferable that tungsten (W) or molybdenum (Mo) is used as the refractory metal.

  Of refractory metals, silicide portions using tungsten or molybdenum as a silicide metal are particularly difficult to dissolve in, for example, a hydrogen fluoride release etching solution. Therefore, according to the above-described configuration using the refractory metal as the silicide metal, the structure in the portion that comes into contact with the release etching solution when the movable electrode is released can be stably silicided, thereby further reducing the resistance value. MEMS devices can be provided.

In the MEMS device manufacturing method of the present invention, a fixed electrode made of silicon formed on a semiconductor substrate, a movable electrode made of silicon disposed in a mechanically movable state with a gap from the semiconductor substrate, and a movable electrode A method of manufacturing a MEMS device, comprising: a wiring laminated portion formed around the substrate and covering a part of the fixed electrode, the wiring laminated portion including the wiring, and the fixed electrode on the semiconductor substrate Forming a movable electrode in a form in which a part is formed on the sacrificial layer, forming a wiring laminated portion on the fixed electrode and the movable electrode, and forming the wiring laminated portion and the sacrificial layer A step of releasing the movable electrode by removing a part by etching, and the step of forming the movable electrode includes a step of siliciding the movable electrode with a refractory metal To.
The refractory metal is preferably tungsten (W) or molybdenum (Mo).

  According to this configuration, the structure made of silicon is silicided with a refractory metal such as tungsten or molybdenum that is difficult to dissolve in, for example, a hydrogen fluoride-based release etching solution. It can be silicided. Thereby, the resistance value is further reduced in the entire circuit of the MEMS device, and the MEMS device having excellent operating characteristics can be manufactured.

  In the MEMS device manufacturing method of the present invention, impurity ions are implanted into at least one of the movable electrode and the fixed electrode in at least one of the step of forming the fixed electrode and the step of forming the movable electrode. It is preferable that the process to include is included.

  According to this configuration, the resistance of the silicon film, which is a prototype of the movable electrode and the fixed electrode, which is the structure of the MEMS device, is reduced by impurity ions, and at least the movable electrode is further silicided by the refractory metal. Low resistance is achieved. Therefore, there is a remarkable effect that the resistance value of the entire circuit of the MEMS device is further reduced.

  Hereinafter, embodiments of the MEMS device and the manufacturing method thereof according to the present invention will be described.

(First embodiment)
First, an embodiment of a MEMS device will be described with reference to the drawings. Fig.1 (a) is a top view which shows the structure of suitable embodiment of the MEMS device based on this invention, FIG.1 (b) is the sectional view on the AA line of the same figure (a).

  A MEMS device 70 shown in FIG. 1 includes a fixed electrode 50 provided in a fixed state on a silicon substrate 41, a first interlayer insulating film 52 stacked above a part of the fixed electrode 50, a first The wiring layer 63 includes a wiring layer 63, a second interlayer insulating film 53, a second wiring layer 64, and a protective film 59. Moreover, the movable electrode 60 provided in the movable state in the opening part C2 as the space formed in the approximate center of the wiring lamination | stacking part is provided. The surface of the movable electrode 60 is silicided to form a silicide portion 65.

On the silicon substrate 41, an insulating film 42, which is a silicon oxide film (SiO ₂ , for example, a thermal oxide film), and a nitride film 43 made of silicon nitride (SiN) are stacked in this order. On the nitride film 43, there is provided a fixed electrode 50 formed by laminating a polycrystalline silicon film by a CVD method or the like and then patterning it. In the fixed electrode 50, impurity ions such as phosphorus ions are implanted into the polycrystalline silicon film at the stage where the polycrystalline silicon film before patterning is deposited.

A sacrificial layer 51 is laminated on a part of the fixed electrode 50. Further, the sacrificial layer 51 includes a first interlayer insulating film 52, a first wiring layer 63, a second interlayer insulating film 53, and a second wiring layer 64. It has the wiring lamination | stacking part laminated | stacked in order. A part of the first interlayer insulating film 52 and the sacrificial layer 51 is patterned, and the fixed electrode 50 and the first wiring layer 63 are conducted. Further, a part of the second interlayer insulating film 53 is patterned, and the first wiring layer 63 and the second wiring layer 64 are electrically connected. A protective film (passivation film) 59 is laminated on the second wiring layer 64.
In the present embodiment, a configuration of a wiring laminated portion having two wiring layers of a first wiring layer 63 and a second wiring layer 64 on the first interlayer insulating film 52 with the second interlayer insulating film 53 interposed therebetween. However, the present invention is not limited to this, and it is also possible to provide a wiring laminate portion having one or three or more wiring layers.

  The sacrificial layer 51, the first interlayer insulating film 52, the first wiring layer 63, the second interlayer insulating film 53, the second wiring layer 64, and the protective film 59 are formed in a cylindrical shape at the approximate center of the wiring stacked portion. Or the opening part C2 which is a rectangular recessed part is formed. A movable electrode 60 formed by laminating a polycrystalline silicon film by a CVD method or the like and then patterning is provided at the concave bottom portion of the opening C2. The movable electrode 60 is partially supported on the nitride film 43 and the sacrificial layer 51 in the lower part of the movable electrode 60 is removed, so that the movable electrode 60 has a predetermined gap from the nitride film 43 and the fixed electrode 50. It is provided in a movable state.

  In the movable electrode 60, impurity ions such as phosphorus ions are ion-implanted into the polycrystalline silicon film when the polycrystalline silicon film before patterning is deposited. Further, the upper surface and a part of the side surface of the movable electrode 60 into which the impurity ions are implanted are silicided with a silicide metal made of a refractory metal and have a silicide portion 65.

As described above, the movable electrode 60 made of polycrystalline silicon is subjected to impurity implantation by ion implantation, and is partly silicided to form a silicide portion 65.
As a result, the sheet resistance value of the movable electrode 60 can be reduced to about 1/100 as compared with a method of reducing the resistance by only implanting impurities into the polycrystalline silicon. Therefore, the MEMS device 70 can improve the insertion loss and pass characteristic when operated, and has excellent operation characteristics applicable to a high frequency device or the like.

Next, an example of the operation of the MEMS device 70 having the above configuration will be described. In the present embodiment, one of the fixed electrodes 50 formed on both sides of the movable electrode 60 will be described as a drive electrode and the other as a detection electrode. It is assumed that an appropriate series bias voltage is applied to the movable electrode 60.
When a drive voltage is injected into the drive electrode side of the fixed electrode 50 of the MEMS device 70, a potential difference is generated between the fixed electrode 50 and the movable electrode 60, and charges are stored accordingly. Due to the time change of the potential or the time change of the stored charge, an alternating current flows between the drive electrode side of the fixed electrode 50 and the movable electrode 60 as in a normal capacitor. This is the same between the detection electrode side of the fixed electrode 50 and the movable electrode 60, and an alternating current corresponding to the capacitance value when two capacitors are connected in series flows through the entire MEMS device 70.
On the other hand, the movable electrode 60 has a specific vibration frequency at a specific frequency, and bends in the thickness direction at the specific frequency. In this case, the capacitance between the drive electrode side and detection electrode side of the fixed electrode 50 described above and the movable electrode 60 is displaced, and charges corresponding to the voltage are stored in the capacitors formed between the structures. However, when the capacitance fluctuates, the charge moves to satisfy the charged amount Q = CV in the capacitor. As a result, at the natural vibration frequency of the movable electrode 60, a current flows with a change in capacitance. The output current from the movable electrode 60 is detected from the detection electrode side of the fixed electrode 50.

(Second Embodiment)
Next, a method for manufacturing the MEMS device 70 of the first embodiment will be described. 2 and 3 are schematic cross-sectional views for explaining a manufacturing process of the MEMS device 70. 2 and 3 show a cross section of the MEMS device 70 at the same position as that in FIG.

In manufacturing the MEMS device 70, a semiconductor manufacturing process is used.
In FIG. 2A, an insulating film 42 made of a silicon oxide film (SiO ₂ ) is formed by thermally oxidizing the surface of the silicon substrate 41, and then silicon nitride (SiN) or the like is formed by CVD or sputtering. The formed nitride film 43 is deposited and formed. The nitride film 43 serves as a base layer that functions as an etching stop layer when performing release etching, which will be described later.

Next, a polycrystalline silicon film is stacked on the nitride film 43 by a CVD method or the like, impurity ions such as phosphorus ions (for example, ³¹ P ⁺ ) are ion-implanted, and then fixed by patterning by a photolithography method or the like. An electrode 50 is formed.
Next, a sacrificial layer 51 made of an oxide film such as silicon oxide is formed on the fixed electrode 50 by sputtering or the like. Then, after depositing a polycrystalline silicon film on the sacrificial layer 51 by a CVD method, a sputtering method, a vacuum deposition method, or the like, ion implantation for implanting impurity ions such as phosphorus ions is performed, and then patterning is performed by a photolithography method or the like. By doing so, the movable electrode 60 is formed.
Thus, the fixed electrode 50 and the movable electrode 60 can reduce sheet resistance by impurity ion implantation.

Next, as shown in FIG. 2B, a silicide metal layer 65a made of a refractory metal is laminated on the movable electrode 60 by vacuum deposition, sputtering, CVD, or the like. As the refractory metal for forming the silicide metal layer 65a, tungsten (W) or molybdenum (Mo) is preferably used. Subsequently, annealing is performed for a predetermined time at a predetermined temperature by lamp annealing or the like, and as shown in FIG. 2C, the surface of the movable electrode 60 in contact with the silicide metal layer 65a is silicided to form a silicide portion. 65 is formed.
Thus, by forming a silicide portion 65 by siliciding a part of the movable electrode 60, the sheet resistance of the silicide portion 65 can be further reduced. As a result, the sheet resistance of the entire MEMS device 70 can be significantly reduced. Therefore, the MEMS device having excellent operating characteristics with improved insertion loss and passing characteristics when the MEMS device 70 is operated. 70 can be manufactured.

Subsequently, as shown in FIG. 3A, the silicide metal layer 65a which has not been silicided is removed by etching with an aqueous solution of ammonia (NH ₄ ) and hydrogen peroxide (H ₂ O ₂ ). Then, an oxide film 66 is formed on the silicide portion 65. Note that the etching solution used here is not limited to an aqueous solution of ammonia and hydrogen peroxide, and other etching solutions having a selection ratio for etching only the unreacted silicide metal layer 65a while leaving the silicide portion 65 may be used. Good.

  Next, as shown in FIG. 3B, a first interlayer insulating film 52 is formed by a method such as sputtering so as to cover the silicide portion 65 and the movable electrode 60 on which the oxide film 66 is formed. . At this time, the base layer on which the first interlayer insulating film 52 is laminated has irregularities, but in order to facilitate the formation of a wiring layer or the like laminated on the first interlayer insulating film 52 in a later step, the first interlayer insulating film 52 is laminated. It is desirable that the upper surface of the insulating film 52 be flat. Therefore, it is preferable to use BPSG (Boron Phosphorus Silicon Glass) or PSG (Phosphorus Silicon Glass) that can be planarized by reflowing for the first interlayer insulating film 52. In addition, SOG (Spin On Glass), which is formed by applying a liquid insulating glass material by spin coating, is used as an interlayer insulating film, or after chemical sputtering and sputtering of silicon oxide or the like. Alternatively, the upper surface of the interlayer insulating film may be planarized using a planarization technique such as CMP (Chemical Mechanical Polishing).

Next, in FIG. 3C, a first wiring layer 63, a second interlayer insulating film 53, and a second wiring layer 64 are formed on the first interlayer insulating film 52 by sputtering, CVD, photolithography, or the like. Are laminated and patterned in this order. The first wiring layer 63 and the second wiring layer 64 have a plurality of wirings (not shown) made of silicon oxide (SiO ₂ ) or the like, and lead the wirings from the fixed electrode 50. In this embodiment, the example in which the two wiring layers of the first wiring layer 63 and the second wiring layer 64 are formed has been described. Here, the wiring layer may be a single layer, or three or more wiring layers may be provided as necessary.

Next, a protective film 59 made of silicon nitride or the like is formed on the second wiring layer 64. The protective film 59 can be deposited by CVD or sputtering. In addition, the protective film 59 made of silicon nitride (Si ₃ N ₄ ) is preferably formed using, for example, plasma CVD.

  Next, release etching of the movable electrode 60 is performed. In the release etching, for example, hydrogen fluoride (HF) having a selection ratio for etching each layer made of single crystal silicon oxide other than the fixed electrode 50 and the movable electrode 60 made of polycrystalline silicon and the nitride film 43 made of silicon nitride. ) -Based etching solution.

  In FIG. 3D, first, a photoresist pattern (not shown) for forming the opening C2 is formed, and this photoresist pattern is used as an etching mask to perform wet etching with a hydrogen fluoride-based etchant. Then, the protective film 59, the second interlayer insulating film 53, the first interlayer insulating film 52, the oxide film 66 covering the upper and side surfaces of the movable electrode 60, and the sacrificial layer 51 in the lower part of the movable electrode 60 are sequentially removed. Thus, the opening C2 is formed. In this release etching, the etching in the thickness direction is stopped by the nitride film 43 functioning as an etching stop layer, and the fixed electrode 50 remains without being etched. Further, by removing the sacrificial layer 51 in the lower portion of the movable electrode 60, the movable electrode 60 is released with a predetermined gap from the nitride film 43 and the fixed electrode 50, and becomes movable.

Here, depending on the type of silicide metal for siliciding the movable electrode 60, the silicide portion dissolves in the hydrogen fluoride-based release etching solution, and conversely the sheet resistance increases or the structure becomes thin. There is a risk of causing problems such as fluctuations in general characteristics. According to the manufacturing method of the present embodiment, tungsten or molybdenum, which is a refractory metal, is used as the silicide metal. A silicide portion formed by using a refractory metal as a silicide metal has a characteristic that it is difficult to dissolve in a hydrogen fluoride-based release etching solution, and this characteristic is particularly remarkable when tungsten and molybdenum are used.
Further, in the manufacturing method of the present embodiment, the silicide portion 65 is protected by the oxide film 66 covering the upper surface and side surfaces thereof, so that it does not touch the release etching solution until the oxide film 66 is removed. It is hard to be done.
Accordingly, when the movable electrode 60 is released, the dissolution of the silicide portion 65 by the release etchant can be suppressed. Therefore, the MEMS device 70 including the movable electrode 60 having a reduced resistance by having the silicide portion 65 is provided. Can be manufactured stably.

Note that the release etching may be performed in a plurality of stages in combination with the dry etching method. For example, first, the protective film 59, the second interlayer insulating film 53, and the first interlayer insulating film are formed by the RIE (reactive ion etching) method using, for example, a reactive gas such as CHF ₃ through the photoresist pattern. The film 52 is dry etched to a predetermined depth. Subsequently, release etching is performed with a hydrogen fluoride-based etching solution to release the movable electrode 60. According to this method, dry etching by the RIE method is excellent in anisotropy, and so-called undercut in which the protective film 59 directly under the end portion of the photoresist pattern is hardly etched occurs. In addition, the release etching time can be shortened.

Then, after the release etching, the photoresist pattern is peeled off to complete a series of manufacturing steps of the MEMS device 70.
As described above, in the manufacturing method of the present embodiment, the MEMS device 70 including the fixed electrode 50 having the silicide portion 65 is manufactured by a semiconductor manufacturing process.
As a result, it is relatively easy to manufacture a composite MEMS device in which a MEMS structure and a CMOS such as an oscillation circuit are provided side by side on a silicon substrate 41, and a more versatile MEMS device 70 can be manufactured. it can.

  By the way, generally, when the MEMS structure (movable electrode) formed in a movable state is not silicided, a so-called sticking phenomenon may occur as the MEMS structure is thinner and lower in rigidity. The sticking phenomenon means that in the washing process after release etching, the movable part of the MEMS structure released by release etching is deformed by the surface tension of the washing water such as pure water, and comes into contact with the nearest structural body. It is a phenomenon that does not leave. Such a sticking phenomenon of the movable electrode can be suppressed by a characteristic aspect exhibited by the silicided movable electrode 60 of the MEMS device 70 manufactured by the manufacturing method of the second embodiment.

  Here, the aspect of the movable electrode 60 that suppresses the sticking phenomenon as described above in the MEMS device 70 of the above embodiment will be described with reference to the drawings. FIG. 4 is a diagram for explaining a mode before and after etching around the silicided movable electrode 60 in the method of manufacturing the MEMS device 70 of the second embodiment, and FIG. It is a fragmentary sectional view explaining a state, and the same figure (b) is a fragmentary sectional view explaining the state after release etching.

  4A, an insulating film 42, a nitride film 43, a fixed electrode 50, a sacrificial layer 51, a movable electrode 60, a first interlayer insulating film 52, and a first wiring layer 63 (not shown) are formed on a silicon substrate 41. ), A cross-section of a laminate formed by sequentially laminating a second interlayer insulating film 53, a second wiring layer 64 (not shown), and a protective film 59 is partially illustrated. The movable electrode 60 is silicided to form a silicide portion 65, and an oxide film 66 is further provided on the silicide portion 65.

  When the laminated body is release-etched as shown in FIG. 4B to form the opening C2, the movable electrode 60 is released and becomes movable. At this time, as the movable electrode 60 is thinner and less rigid, the above sticking phenomenon is more likely to occur. For example, the movable electrode 60 may come into contact with the lower fixed electrode 50 and be fixed. However, since the silicided movable electrode 60 has increased rigidity due to the silicide metal made of a refractory metal, there is an effect of suppressing the occurrence of the sticking phenomenon.

  In addition, as shown in FIG. 4B, the silicided movable electrode 60 is warped on the silicide portion 65 side due to the stress acting on the silicide portion 65 formed on the upper surface and the side surface of the movable electrode 60. It is pulled in the direction of the arrow in the figure. Due to this action, the movable electrode 60 is warped in the direction opposite to the nitride film 43 and the fixed electrode 50 which are adjacent to each other with a gap therebetween, so that the effect of suppressing the occurrence of the sticking phenomenon is achieved.

  Note that if the amount of warping when the movable portion of the movable electrode 60 is warped by the stress acting in the direction of the arrow in FIG. 4B is large, the operating characteristics of the MEMS structure may be adversely affected. For this reason, in manufacturing the actual MEMS device 70, the process conditions are adjusted so that the movable electrode 60 is substantially flat. For example, it is possible to control the stress of the silicide portion 65 so that the movable electrode 60 becomes substantially flat by controlling the process conditions such as the annealing temperature when siliciding according to the type of silicide metal. .

  The embodiment of the present invention made by the inventor has been specifically described above, but the present invention is not limited to the above-described embodiment, and various modifications are made without departing from the scope of the present invention. Is possible.

  For example, in the MEMS device 70 of the above embodiment, only the movable electrode 60 is silicided, but the fixed electrode 50 may be silicided. In this case, the fixed electrode may be silicided by a method similar to that for the movable electrode 60, and in the same manner as in the second embodiment described above, a region that is not release-etched, for example, a wiring laminated portion of the fixed electrode, may be used. A method of selectively siliciding the covered portion may be used. In the latter case, it is not necessary to consider the corrosion resistance to the release etchant for the silicide metal to be used, so the silicide metal can be selected with a wide choice.

  According to this configuration, since the fixed electrode can be silicided to reduce the resistance, the resistance value of the entire circuit of the MEMS device is further reduced, and is excellent in that it can be applied to a MEMS device that handles a high frequency band. There is a remarkable effect that a MEMS device can be provided.

  Moreover, in the said embodiment, although the prototype of the movable electrode 60 and the fixed electrode 50 which are the MEMS structures of the MEMS device 70 was formed by patterning polycrystalline silicon, it is not restricted to this. The MEMS structure prototype may be formed of amorphous silicon.

  Since the MEMS structure formed of amorphous silicon does not have a regular crystal arrangement like crystalline silicon, metal fatigue along the crystal grain boundary can be suppressed particularly in the continuous operation of the movable electrode. In addition, amorphous silicon can be used together as a material for the gate electrode of a transistor, for example, and since the film forming temperature is relatively low, a high-performance MEMS device in which a CMOS or the like is restored by an existing semiconductor manufacturing process is manufactured. Is possible.

(A) is a top view explaining schematic structure of the MEMS device which is the 1st Embodiment of this invention, The same figure (b) is the sectional view on the AA line of Fig.1 (a). (A)-(c) is a schematic sectional drawing explaining the manufacturing method of the MEMS device which is the 2nd Embodiment of this invention. (A)-(d) is a schematic sectional drawing explaining the manufacturing method of the MEMS device which is the 2nd Embodiment of this invention. (A) is a fragmentary sectional view explaining the state before release etching of the MEMS device manufactured by the manufacturing method of the 2nd Embodiment of this invention, The same figure (b) demonstrates the state after release etching. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 41 ... Silicon substrate as a semiconductor substrate, 43 ... Nitride film as an etching stop layer, 50 ... Fixed electrode, 52 ... 1st interlayer insulation layer as one of wiring laminated parts, 53 ... As one of wiring laminated parts Second interlayer insulating layer, 63... First wiring layer in which wiring is formed, 64... Second wiring layer in which wiring is formed, 59... Protective film as one of wiring laminated portions, 60. Silicide portion, 65a: metal layer for silicide.

Claims (5)

A fixed electrode made of silicon formed on a semiconductor substrate;
A movable electrode made of silicon disposed in a mechanically movable state with a gap between the semiconductor substrate, and
A wiring stack formed around the movable electrode and covering a part of the fixed electrode, the wiring stack including a wiring; and
Have
A MEMS device, wherein at least the movable electrode is silicided with a refractory metal. The MEMS device according to claim 1, wherein
A MEMS device, wherein tungsten (W) or molybdenum (Mo) is used for the refractory metal. A fixed electrode made of silicon formed on a semiconductor substrate;
A movable electrode made of silicon disposed in a mechanically movable state with a gap between the semiconductor substrate, and
A wiring stack formed around the movable electrode and covering a part of the fixed electrode, the wiring stack including a wiring; and
A method of manufacturing a MEMS device having
Forming a fixed electrode on a semiconductor substrate;
Forming the movable electrode in a manner in which a part is formed on the sacrificial layer;
Forming the wiring laminate on the fixed electrode and the movable electrode;
Removing the wiring laminate and the sacrificial layer by etching to release the movable electrode; and
Have
The method of manufacturing a MEMS device, wherein the step of forming the movable electrode includes a step of siliciding the movable electrode with a refractory metal. In the manufacturing method of the MEMS device of Claim 3,
A method for manufacturing a MEMS device, wherein tungsten (W) or molybdenum (Mo) is used as the refractory metal. In the manufacturing method of the MEMS device of Claim 3 or 4,
At least one of the step of forming the fixed electrode and the step of forming the movable electrode includes a step of ion-implanting impurity ions into at least one of the movable electrode and the fixed electrode, A method for manufacturing a MEMS device.

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