JP2003311692A - Mechanism device and magnetic driving type mechanism device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent metal layers of a beam structure of a mechanism device having a metallic multi-layered structure formed by using a micromachine technology from warping by relieving residual stress and to provide the device at advantageous cost. <P>SOLUTION: In the multi-layered structure part of a beam part 31b of a cantilever beam structure 31, a nickel layer 32a, and an anti-etching layer 32b, the nickel layer 32a is covered with a metal layer (beam part 31b) and a metal layer (anti-etching layer 32b), and the upper face side of the metal layer (anti- etching layer 32b) is formed to be thicker than the metal layer (beam part 31b). Each of the layers is formed using a photolithographic method and an electrolytic plating method. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanical device and a magnetic drive type mechanical device having a beam structure which is formed by using a micromachine technique and has a metal multi-layer structure.

[0002]

2. Description of the Related Art FIG. 8 is a diagram showing a mechanical device of this type, and particularly shows a mechanical device that operates magnetically.

In FIG. 8, 501 is a silicon substrate, 5
Reference numeral 02 is an oxide film as an insulating film formed on the silicon substrate 501. Reference numeral 503 is a lower electrode.
3 is formed by performing patterning with a resist on the oxide film 502 by a semiconductor process (photolithography method) and depositing aluminum using an evaporator.

Reference numeral 504 is a cantilever structure portion serving as an upper electrode formed on the silicon substrate 501 so as to ensure electrical contact with the lower electrode 503. This cantilever structure portion 504 is also formed by vapor-depositing aluminum after a semiconductor process (photolithography method) which is a kind of micromachine technology.

Reference numeral 505 denotes a magnetic substance (cobalt, nickel, iron) as a magnetic drive material, which is provided for providing magnetic properties to the cantilever structure 504 made of aluminum which is a non-magnetic material. Alumina, which is a metal having porosity, is formed on the surface of the cantilever structure 504 by an oxidation method, and a magnetic material is embedded in the holes of the alumina by electrolytic plating.

[0006]

The conventional cantilever structure section 504 has a problem that warping occurs because different metals (here, aluminum and magnetic material) have a multi-layer structure. It is considered that this is because the expansion coefficients of aluminum and the magnetic material that form the multilayer structure are significantly different. That is, in the manufacturing process of stacking metal layers, expansion / contraction due to temperature change is performed,
At this time, it is considered that residual stress is generated at the contact surface between the metals due to the difference in expansion coefficient between the metals, and the residual stress causes warpage.

Further, since the substrate is made of silicon, it is necessary to form an insulating layer. Therefore, an electric furnace is required to form an oxide film, and aluminum is used for the cantilever structure 504. Therefore, there is a problem that it is necessary to vapor-deposit aluminum using a vapor deposition device, which requires manufacturing time and equipment cost.

The present invention has been made to solve the above problems, and in a beam structure having a metal multi-layer structure formed by using a micromachine technique, the residual stress between metal layers is relaxed to prevent warpage, and An object is to provide a mechanical device advantageous in terms of cost.

[0009]

A mechanical device according to the present invention has a beam structure having a multi-layer structure in which a second metal layer is laminated on at least an upper surface of a first metal layer, and the mechanical device is formed by using a micromachine technique. A mechanical device formed, the second
A third metal layer covering the entire surface of the first metal layer is formed by using a photolithography method and an electroplating method, the third metal layer is made of the same material as the first metal, and the first metal layer It is formed thicker than.

[0010]

1 is a sectional view of a mechanical device according to an embodiment of the present invention.

The mechanical device 100 has a substrate 1, a lower electrode 2, a cantilever structure, and an upper electrode 3, which is a main part of the present invention.

The substrate 1 is a so-called printed circuit board in which a copper foil 12 as a conductive material is attached on an insulating substrate 11 made of glass epoxy resin. The copper foil 12 is formed by a semiconductor process (photolithography). After patterning, the copper foil 12 is wet-etched with ferric chloride, which is an etching solution, whereby unnecessary copper foil portions are removed to form a wiring pattern, and the lower electrode 2 is formed on the wiring pattern. , The upper electrode 3 is electrically connected. In the following, the portion of the copper foil 12 that contacts the lower electrode 2 will be referred to as the lower electrode copper foil 12a and the upper electrode 3 as appropriate.
The portion that comes into contact with will be distinguished as the upper electrode copper foil 12b.

The lower electrode 2 has a structure in which the entire surface of the lower electrode copper foil 12a is covered with a nickel layer 21 as a magnetic layer, and the entire surface of the nickel layer 21 is covered with a conductive layer 22. The nickel layer 21 and the conductive layer 22 are formed by using a semiconductor process (photolithography method) and electrolytic plating method, which will be described in detail below, respectively, and the conductive layer 22 is made of gold (contact material). here,
Since gold is resistant to corrosion, the nickel layer 21 can be prevented from being oxidized by covering the nickel layer 21 with gold, and the conductive layer 22 itself can be prevented from being oxidized, so that the contact resistance is prevented from increasing and the initial resistance is reduced. It is possible to maintain conductivity and stabilize contact performance. Further, the material forming the conductive layer 22 also needs to have a role of protecting the nickel layer 21 from being corroded during wet etching in the final step (described later) in manufacturing the mechanical device 100 of the present invention. Therefore, also from this point of view, gold having etching resistance against the etching solution (ferric chloride here) used in the wet etching in the final step is used.

The upper electrode 3 has a cantilever structure portion 31 and a magnetic material portion 32 which are respectively formed by a photolithography method and an electrolytic plating method. The cantilever structure portion 31 includes a base portion 31a whose bottom surface is in contact with the upper electrode copper foil 12b, and a beam portion 31 supported by the base portion 31a.
b and is made of gold (contact material) which is a conductive material having etching resistance. The base 31
a is configured to cover the entire surface of the upper electrode copper foil 12b.

Here, by using gold as the contact material, it is possible to stabilize the contact performance as described above. Since gold is a material having low hardness and flexibility, the cantilever structure portion 31 is made of gold, and the beam portion 31b is attracted to the lower electrode 2 side by magnetic force, which will be described in detail below. At this time, it becomes possible to operate even with a minute magnetic force, and thus the highly sensitive mechanical device 100.
Can be configured. Also, the mechanical device 10
Gold is also used because it is required to have resistance to wet etching in the final step (described later) in manufacturing 0. Further, since the side surface of the upper electrode copper foil 12b is covered with the base portion 31a of the cantilever structure portion 31, it is possible to prevent the upper electrode copper foil 12b from being etched during the wet etching in the final step. It is like this.

The magnetic body portion 32 has a structure in which the entire surface of the nickel layer 32a as a magnetic layer is covered with the etching resistant layer 32b. The nickel layer 32a and the etching resistant layer 32b are formed by a photolithography method and an electrolytic plating method, respectively, and the etching resistant layer 32b is made of gold. By using gold for the etching resistant layer 32b, as described above, the nickel layer 32 is formed.
It is possible to prevent a from being oxidized, and it is possible to protect the nickel layer 32a from being etched during wet etching in the final step (described later) in manufacturing the mechanical device 100.

The upper electrode 3 thus constructed is shown in FIG.
As is clear from the above, the multi-layer structure includes the gold layer (beam portion 31b), the nickel layer 32a, and the gold layer (etching resistant layer 32b). Therefore, residual stress is generated between the layers. Here, in the present invention, in the multilayer structure portion, the entire surface of the nickel layer 32a laminated on the gold layer (beam portion 31b),
That is, the side surface and the upper surface of the nickel layer 32a are covered with a gold layer (etching resistant layer 32b), and the nickel layer 32
a gold layer (etching resistant layer 3
2b) is formed to be thicker than the gold layer (beam portion 31b) contacting the bottom surface of the nickel layer 32a. As a result, the residual stress is relieved and the warp can be prevented.

Further, in the upper electrode 3, when the beam portion 31b is bent downward by magnetic force so that the lower electrode 2 is electrically contacted, the tip portion of the beam portion 31b is brought into contact with the lower electrode 2. It is formed on the substrate 1 so as to be in contact with each other.

The lower electrode 2 and the upper electrode 3 are formed on the substrate so that their upper surfaces are parallel to the substrate surface.

The dimensions of each part of the mechanical device 100 in this embodiment are as follows. That is,
The substrate 1 has a length of 2 cm and a width of 1.5 cm, the thickness of the copper foil portion is 9 μm, and the length, width and thickness of the lower electrode 2 are 1 each.
300μm, 900μm, 11μm (This thickness includes the thickness of copper foil 9μm, other details are nickel layer 2
1 has a thickness of 1 μm, the conductive layer 22 has a thickness of 1 μm), and the length, width, and thickness of the beam portion 31b of the cantilever structure portion 31 are 1 respectively.
000 μm, 150 μm, 1 μm, the length of the base portion 31a,
Width and thickness are 1000μm, 800μm, and 10μ, respectively.
m (this thickness includes a copper foil thickness of 9 μm, and the portion made of gold is 1 μm). The length, width, and thickness of the magnetic body portion 32 are 700 μm, 60 μm, and 12 μ, respectively.
m (the thickness of the nickel layer 32a is 10 μm, the thickness of the etching resistant layer 32b is 2 μm).

FIG. 2 is an explanatory view of the operation of the mechanical device shown in FIG. In FIG. 2, reference numeral 41 is an electromagnet installed directly below the lower electrode 2 in order to sufficiently narrow the magnetic distance to the beam portion 31b. A magnetic field 42 is generated by applying a voltage to the electromagnet 41, and the magnetic layer 42 magnetizes the nickel layer 32a of the upper electrode 3 and the nickel layer 21 of the lower electrode 2 so that the nickel layer 32a on the upper electrode 3 side and the lower electrode 32a are magnetized. A magnetic attraction force is generated between the nickel layers 21 on the second side. As a result, the beam portion 31b of the upper electrode 3 is changed to the lower electrode 2
The lower end of the beam portion 31b comes into contact with the lower electrode 2 and the switch is turned on. When the application of the voltage to the electromagnet 41 is stopped, the magnetic field 42 disappears, and since nickel has a low residual magnetic susceptibility, the magnetic attraction force between the nickel layers 32 a and 21 also disappears due to the disappearance of the magnetic field 42. Then, the beam portion 31b returns to the non-contact state by the elastic force of itself and is turned off. In the mechanical device 100 of the present embodiment configured with the above dimensions, the electromagnet 41 to 7 mT
It was confirmed that the magnetic force (measured by Tesla meter) works as a switch. The experimental results are shown below.

FIG. 3 is a diagram showing operation waveforms of the mechanical device with respect to the coil waveform. Here, 1 for the electromagnet 41
The operation waveform of the mechanical device 100 when a voltage of 00V is applied and a signal (10 Hz) is input to the gate from a transmitter (not shown) using a transistor (not shown) to turn the magnetic field 42 on and off is shown. A voltage of 1V is applied to the mechanical device 100. From FIG. 3, it is shown that the mechanical device 100 is turned on / off at the same time as the magnetic field 42 is turned on / off.
Through this experiment, the operation as the mechanical device 100 was confirmed.

Next, a method of manufacturing the mechanical device shown in FIG. 1 will be described. The mechanical device 100 is manufactured by using a micromachine technology, and for the micromachine technology, a semiconductor process (photolithography) used for manufacturing ICs, LSIs and the like is used. Hereinafter, the manufacturing method will be described in detail.

4 to 7 are explanatory views of a method of manufacturing a mechanical device. Hereinafter, each drawing will be described in order.

4 (a) to 4 (d) are sectional views, and FIG. 4 (e) is a plan view of FIG. 4 (d). First, on the unprocessed substrate 1 shown in (a),
(B) applying a photoresist film 43 on the surface of the substrate 1,
The photoresist film 43 is exposed with a mask aligner and developed with a developing solution to expose (open) a portion of the copper foil 12 other than a portion to be a wiring pattern.
Are formed (photolithography process). And
(C) Wet etching is performed with ferric chloride to remove a portion of the copper foil 12 corresponding to the opening pattern 44, that is, a portion not masked by the photoresist film 43 to expose the insulating substrate 11, and (d) (e) ) Photoresist film 43
Is removed (photoresist film removing step), and a wiring pattern having the copper foil 12a for the lower electrode and the copper foil 12b for the upper electrode is formed on the copper foil 12.

FIGS. 5A to 5D are views showing the manufacturing process of the lower electrode. Next, (a) a photoresist film 51 is applied on the surface of the substrate 1, the photoresist film 51 is exposed by a mask aligner, and developed with a developing solution to form an opening pattern 61 for forming a lower electrode on the photoresist film 51. Form (photolithography process). Then, (b) nickel 21 is laminated on the opening pattern 61 portion by an electrolytic plating apparatus (electrolytic plating step). During this electrolytic plating, the nickel layer 21 is laminated so as to cover the entire surface of the lower electrode copper foil 12a. Then, as in (c), gold 22 is laminated on the opening pattern 61 by an electrolytic plating apparatus (electrolytic plating step). In this electrolytic plating, gold 22
Are laminated so as to cover the entire surface of the nickel layer 21. Then, (d) the photoresist film 51 is removed (photoresist film removing step) to form the lower electrode 2 having a structure in which the entire surface of the nickel layer 21 is covered with gold 22.

5 and 6 are views showing the manufacturing process of the upper electrode. First, the photoresist film 53 is applied onto the substrate 1 including the lower electrode 2 shown in FIG.
3 is exposed with a mask aligner and developed with a developing solution, and an opening pattern 63 for forming a sacrificial layer is formed on the photoresist film 53.
Are formed (photolithography process). And
(B) Nickel 71 is laminated on this opening pattern 63 by an electroplating apparatus (electrolytic plating step), and (c)
The photoresist film 53 is removed (photoresist film removing step), and the sacrificial layer 71 is formed on the substrate 1 and the lower electrode 2.

Similarly, (d) a photoresist film 54 is coated on the substrate 1 including the lower electrode 2 and the sacrificial layer 71, the photoresist film 54 is exposed with a mask aligner, and the photoresist film 54 is developed with a developing solution. An opening pattern 64 for forming a cantilever structure layer is formed in the resist film 54 (photolithography process). Then, (e) gold 31 is laminated on the opening pattern portion by an electrolytic plating apparatus (electrolytic plating step). During this electrolytic plating, the gold 31 is contacted with the upper electrode copper foil 12b at the contact surface with the upper electrode copper foil 1b.
It is laminated so as to cover the entire surface of 2b. And
(F) The photoresist film 54 is removed (photoresist film removing step), and the structural layer 3 is formed on the substrate 1 and the sacrificial layer 71.
1 is formed.

Then, the lower electrode 2 and the sacrificial layer 7 shown in FIG.
1 and the structural layer 31 on the substrate 1, a photoresist film 55 is applied, the photoresist film 55 is exposed by a mask aligner, and is developed with a developing solution to form a photoresist film 55.
Then, an opening pattern 65 for forming a magnetic layer of the upper electrode 3 (see FIG. 1) is formed (photolithography process). Then, (b) nickel 32a is laminated on this opening pattern 65 portion by an electrolytic plating apparatus (electrolytic plating step),
(C) The photoresist film 55 is removed (photoresist film removing step), and the nickel layer 32a is formed on the substrate 1.

Then, (d) the lower electrode 2, the sacrificial layer 71,
A photoresist film 56 is applied on the substrate 1 including the structure layer 31 and the nickel layer 32a, the photoresist film 56 is exposed with a mask aligner, and is developed with a developing solution to form an etching resistant layer on the photoresist film 56. The opening pattern 66 is formed (photolithography process). And
(E) Gold 32b is laminated on this opening pattern 66 portion by an electroplating apparatus (electrolytic plating step), (f) photoresist film 56 is removed (photoresist film removing step), nickel layer 32a on substrate 1 The entire surface of gold 32b
The magnetic body part 32 covered with is formed.

Then, as a final step, wet etching is performed using ferric chloride as an etching solution to selectively remove the sacrificial layer 71 and the unnecessary copper foil 12 portion of the substrate 1. As a result, the mechanical device 100 as shown in FIG. 1 is manufactured.

As described above, according to the present embodiment, the mechanical stress in which the residual stress between the gold layer (beam portion 31b), the nickel layer 32a, and the gold layer (etching resistant layer 32b) is relaxed and warpage is prevented. It is possible to obtain 100.

In the above description, the mechanical device 100 having a magnetically driven cantilever structure and including wet etching in the manufacturing process has been described as an example. Therefore, each layer constituting the multi-layer structure has a magnetic structure. Although it has been described as using nickel having gold and gold having etching resistance, it is not limited to this, and a metal satisfying the properties (here, magnetism and etching resistance) required for each layer is used. In other words, in the multilayer structure portion, the third metal layer formed of the same material as the first metal layer over the entire surface of the second metal laminated on the first metal layer is essential. And the third metal layer may be formed thicker than the first metal layer.

In the above description, the stress relief between the metal layers is intended for the magnetically operated cantilever structure. However, the cantilever structure is not limited to the cantilever structure, and the cantilever structure is formed by using the micromachine technique. If the beam structure has a multi-layer structure, the stress can be relaxed by adopting the above configuration.

Further, the mechanical device 100 of the present embodiment.
Is formed by using a micromachine technique such as a semiconductor process (photolithography method) or an electrolytic plating method, so that it can be miniaturized to a unit of several microns. Further, the mechanical device 100, which is advantageous in terms of manufacturing time and equipment cost, can be obtained because it is manufactured using the photolithography method and the electrolytic plating method, which are excellent in shortening the manufacturing time and cost. It should be noted that this type of mechanical device is used by being incorporated in various devices such as communication devices.
Since 00 can be miniaturized to a unit of several microns, it is possible to contribute to miniaturization of equipment in which the mechanical device 100 is incorporated.

Further, as is clear from the experimental results of FIG. 3, the mechanical device 100 can function as a switch operated by magnetic force, and the cantilever structure portion 31 which is its movable portion has flexibility. Since it is made of gold, it is possible to form a highly sensitive magnetic drive type switch that can operate even with a minute magnetic force as described above.

Since the semiconductor device can be manufactured only by the semiconductor process (photolithography) and electrolytic plating, it can be manufactured on the substrate 1. Therefore, by reducing the design value to a micro unit, a plurality (several tens) can be formed on one substrate. The number of mechanical devices 100 can be manufactured, and mass production is also possible.

In this mass production, in the above photolithography process, a plurality of opening patterns for predetermined layers are formed on the substrate 1 at appropriate intervals, electrolytic plating is performed on each opening pattern portion, and then the photoresist is formed. By repeating the work of removing the film by etching and forming the predetermined layer, a plurality of mechanical devices can be manufactured at the same time, and the manufacturing time can be shortened. In this way, the integration and mass production can contribute to the reduction of production cost.

In manufacturing the mechanical device 100,
Since there are no time-consuming manufacturing processes such as chemical vapor deposition (CVD) and physical vapor deposition (PVD) (sputtering method, vapor deposition method), the manufacturing time can be shortened.

By the way, at present, a micromachine is generally manufactured on a silicon substrate. However, the mechanical device having the cantilever structure of the present invention is manufactured on a printed circuit board, and therefore, a substrate material is used. From the aspect, cost reduction can be expected compared to the silicon substrate.

Further, since the printed board does not require the step of forming an insulating layer (oxide film) by the electric furnace thermal oxidation method which is necessary when using a silicon substrate, the manufacturing cost can be reduced and the insulating layer can be formed. Since formation is a time-consuming process, the elimination of this process can contribute to a reduction in manufacturing time.

[0042]

As described above in detail, according to the present invention, the stress between the first metal layer, the second metal layer and the third metal layer is relieved, warpage is prevented, and the cost is advantageous. It is possible to obtain a mechanical device having a flexible beam structure.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a mechanical device according to an embodiment of the present invention.

FIG. 2 is an operation explanatory view of the mechanical device of FIG.

FIG. 3 is a diagram showing an operation waveform of a mechanical device with respect to a coil waveform.

FIG. 4 is a diagram showing a manufacturing process of a wiring pattern of a copper foil.

FIG. 5 is a diagram showing a manufacturing process of a lower electrode.

FIG. 6 is a view (No. 1) showing the manufacturing process of the upper electrode.

FIG. 7 is a view (No. 2) showing the manufacturing process of the upper electrode.

FIG. 8 is a diagram showing a conventional mechanical device.

[Explanation of reference numerals] 1 substrate 2 lower electrode 3 upper electrode 11 insulating substrate 12 copper foils 43, 51, 53 to 56 photoresist film 21 nickel layer (second nickel layer) 22 conductive layer 31 cantilever structure (structure Layer) 31a base portion 31b beam portion (first metal layer) 32 magnetic body portion 32a nickel layer (second metal layer, first nickel layer) 32b etching resistant layer (third metal layer) 42 magnetic field 44, 61 , 63 to 66 Aperture pattern 100 Mechanical device (Magnetic drive mechanical device)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tatsuro Kobayashi             1 share of Hachioji Higashi-Asakawacho 550, Tokyo             In the company Oki sensor device (72) Inventor Yoichi Sato             2-33 Takanawa, Minato-ku, Tokyo School corporation             Tokai University Junior College

Claims (5)

[Claims] 1. A mechanical device having a beam structure having a multi-layered structure in which a second metal layer is laminated on at least an upper surface of a first metal layer, and the mechanical device is formed by using a micromachining technique. Forming a third metal layer covering the entire surface of the metal layer by using a photolithography method and an electrolytic plating method,
A mechanical device, wherein the third metal layer is made of the same material as the first metal and is formed thicker than the first metal layer. 2. The beam structure is a cantilever structure in which the first metal layer has a cantilever shape, and the cantilever structure has a base portion and a beam portion supported by the base portion. The second metal layer and the third metal layer are provided on the beam portion,
The mechanical device according to claim 1, wherein the third metal layer is configured to be thicker than a portion of the first metal layer corresponding to the beam portion. 3. The mechanical device according to claim 1 or 2, wherein the first metal layer is a gold layer and the second metal layer is a first nickel layer. 4. A wiring pattern is formed of copper foil on an insulating substrate, and the bottom surface of the base of the mechanical device according to claim 3 is electrically connected to a wiring pattern portion of the wiring pattern for a cantilever structure. And a lower electrode having a second nickel layer and a conductive layer covering the entire surface of the second nickel layer is electrically connected to the lower electrode wiring pattern portion of the wiring pattern. And the lower electrode is
An external magnetic field is applied to cause the first nickel layer to move to the second layer.
The magnetic drive mechanism device, wherein the magnetic drive mechanism device is formed on the substrate so as to come into contact with the beam when the beam is attracted to the lower electrode by being magnetized with the nickel layer. 5. The magnetic drive type mechanical device according to claim 4, wherein each of the conductive layer and the second nickel layer is formed by using a photolithography method and an electrolytic plating method.