JP2002170470A - Semiconductor micro relay and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor micro relay of vertical open/close type together with its manufacturing method, which is manufactured in a relatively simple manufacturing process with no constraint on a structure design. SOLUTION: There are provided a semiconductor substrate 1, an insulating layer 7 formed on it, a fixed conductive part 21 formed by plating on the insulating layer 7, a beam-like movable conductive part 31 so formed by plating as to face the fixed conductive part 21 with an interval while electrically separated, a support part 51 which rises above the fixed conductive part 21 to connect to a part of the movable conductive part 31 so that the movable conductive part 31 is physically supported on the substrate 1, and an acting part 8 which, formed on the movable conductive part 31, deflects a part of it in the direction vertical to the surface of the semiconductor substrate 1 so as to be electrically conductive to the fixed conductive part 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor microrelay and a method for manufacturing the same, and more particularly, to a semiconductor microrelay realizing a contact structure which can be opened and closed in a vertical direction on a substrate surface by plating a semiconductor substrate. It relates to a manufacturing method.

[0002]

2. Description of the Related Art In general, a vertical opening / closing type semiconductor microrelay having a contact structure that opens and closes in a vertical direction on a substrate surface of a semiconductor substrate is provided on a base substrate with a beam-like movable surface facing the base substrate with a clearance therebetween. The movable portion and the base substrate are supported and fixed so as to be able to bend in the vertical direction of the substrate surface, and electrodes are formed at contact positions between the movable portion and the base substrate to form a switching contact portion. Conventional semiconductor micro relays of this type mainly use micro processing such as formation of recesses and openings by anisotropic etching and the like, and formation of voids by removal of an oxide film layer or a buried sacrificial layer. In this way, the opening and closing structure of the contact portion was realized by processing. However, microfabrication of a silicon substrate generally depends on the crystal orientation of silicon and is therefore limited in the degree of freedom in structural design, and requires a complicated manufacturing process to form an intended structure. Was. On the other hand, there is also known a semiconductor microrelay in which a contact switching structure is formed by a plating layer provided on a semiconductor substrate. However, in this case, operating parts of switching contacts are arranged side by side in a plane direction of the substrate and these are opened and closed in the horizontal direction. It was of the horizontal opening and closing type.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a vertical opening / closing type which can be manufactured by a relatively simple manufacturing process without being restricted by a structural design. And a method of manufacturing the same.

[0004]

According to a first aspect of the present invention, there is provided a semiconductor microrelay, comprising: a semiconductor substrate; an insulating layer formed on the substrate; a fixed conductive portion formed on the insulating layer by plating; A beam-shaped movable conductive portion formed by plating so as to face the fixed conductive portion at an interval while being electrically separated from the fixed conductive portion, and rise up above the fixed conductive portion to form a part of the movable conductive portion. A supporting portion connected to the substrate to physically support the movable conductive portion, and the semiconductor substrate formed on the movable conductive portion and electrically connecting a part of the movable conductive portion to the fixed conductive portion. And an operating portion for bending the substrate surface in the vertical direction. In this semiconductor micro relay, the movable conductive part is bent toward the substrate surface by the action of the operating part and becomes conductive with the fixed conductive part, thereby serving as a relay. Since the and the movable conductive portion are both formed by plating, it can be manufactured in a relatively simple process by a combination of the plating and the lamination process of the mask. Further, there is no restriction on the structural design due to the characteristics of the material such as the crystal orientation of the substrate as in the related art.

According to a second aspect of the present invention, there is provided the semiconductor micro relay of the first aspect, wherein the movable conductive portion has a contact portion which is electrically connected to the fixed conductive portion when the movable conductive portion is bent. It is characterized by being abutted. In this case, the projecting contact portion can surely make contact with the contact portion of the fixed conductive portion.

Here, the operating portion bends the movable conductive portion toward the surface of the substrate, and the operating portion may act on the movable conductive portion by itself, or may cooperate with the movable conductive portion. You may do. That is, the actuating section may be one that acts on the movable conductive section by itself, such as a piezoelectric element as described in claim 3 or a shape memory alloy as described in claim 4. It may be provided as a thin film layer having a larger thermal expansion coefficient than that of the movable conductive portion and function as a so-called bimetal which cooperates with the movable conductive portion. In a semiconductor microrelay in which the operating section is a piezoelectric element, when a voltage is applied to the piezoelectric element, the operating section operates the movable conductive section toward the substrate surface. Therefore, the contact part of the movable conductive part and the contact part of the fixed conductive part come into contact with each other. In the semiconductor micro relay in which the operating part is a shape memory alloy as described in claim 4, since the heating means for heating the movable conductive part is provided, the heating part heats the operating part. Then, the shape memory alloy as the operating portion is deformed, and the movable conductive portion is operated toward the substrate surface, so that the contact portion of the movable conductive portion comes into contact with the contact portion of the fixed conductive portion. A semiconductor microrelay according to claim 5, wherein the operating portion is a thin film layer having a larger coefficient of thermal expansion than the movable conductive portion, since the heating portion for heating the movable conductive portion is provided. When actuated, the operating portion expands more than the movable conductive portion, and the action of the bimetal causes the operating portion to actuate the movable conductive portion toward the substrate surface, and thus the contact portion of the movable conductive portion. And the contact portion of the fixed conductive portion contacts.

A method of manufacturing a semiconductor micro relay according to claim 6, wherein an insulating layer is provided on a substrate, and a base conductive portion and a fixed conductive portion are formed by plating while being electrically separated on the insulating layer; A step of loading a resist at a location other than the base conductive part, and a starting part on the base conductive part,
Forming a movable conductive portion on the resist by plating, removing the resist to form a void, and mounting the movable conductive portion on the movable conductive portion in contact with the void. Mounting an operating part that operates in a vertical direction with respect to the surface. In this step, the space between the movable conductive part and the fixed conductive part can be increased by increasing the thickness of the resist. Therefore, a semiconductor microrelay with a large space is manufactured. Further, by adjusting the plating conditions, the internal stress existing in the movable conductive portion can be freely controlled, and the occurrence of warpage of the movable conductive portion can be suppressed. In addition, since this semiconductor micro relay is formed by the steps of lamination of plating, loading of resist, and removal of resist, the manufacturing process is relatively simple, and the characteristics of the material, such as the crystal orientation of the substrate, are not considered. Can be manufactured.

According to a seventh aspect of the present invention, in the method of manufacturing a semiconductor microrelay according to the sixth aspect, in the resist forming step, an upper surface of the stacked resist layer is provided with a contact of the movable conductive portion. A recess is provided at a corresponding position. By this step, a semiconductor micro relay from which the contact portion of the movable conductive part is projected is manufactured by the steps of stacking plating, loading resist, and removing resist.

[0009]

Embodiments of the present invention will be described below.

FIG. 1 is a perspective view showing the structure of the semiconductor micro relay according to the embodiment. On an N-type silicon substrate 1 (hereinafter referred to as a silicon substrate 1) having an insulating layer (silicon oxide film) 7 formed on the surface, two fixed conductive portions 21a,
21b is provided. These two fixed conductive parts 21
A movable conductive part 31 formed by plating is provided in a beam shape so as to oppose at a distance while being electrically separated from a and 21b, and is higher than the two fixed conductive parts 21a and 21b. The substrate 1 is provided with a supporting portion 51 that rises to the position and is connected to a part of the movable conductive portion 31 and physically supports the movable conductive portion 31 with respect to the substrate 1. This support 51
Is composed of a base conductive portion 20 described later, a second conductive layer 5 described below mounted on the base conductive portion 20, and a second plating layer 6 described later. Further, on the movable conductive part 31, a part of the movable conductive part 31 is divided into two fixed conductive parts 21a and 21b.
An operating section 8 is provided to bend in the vertical direction of the surface of the silicon substrate 1 so as to be electrically connected to the silicon substrate 1. This operating part 8
Can be provided, for example, as a piezoelectric element 35 (FIG. 1), a shape memory alloy 36 (FIG. 4), or a thin film layer 37 (FIG. 5) having a larger thermal expansion coefficient than the movable conductive part 31 described later. .

The movable conductive part 31 is bent in the direction of the silicon substrate 1 in the vertical direction of the substrate surface by the operating part 8, and the movable conductive part 3
1 contacts the two fixed conductive portions 21a and 21b. As a result, the two fixed conductive portions 21a and 21b enter a state of being electrically conductive.

FIG. 2 shows an example of a method for manufacturing a semiconductor microrelay.

First, after an insulating layer (silicon oxide film) 7 is formed on the silicon substrate 1, the first conductive layer 2 is formed by an apparatus such as electron beam evaporation (hereinafter referred to as EB evaporation) or sputtering. The material of the first conductive layer 2 is a first plating layer 4 described later.
For example, when the material of the first plating layer 4 is nickel, nickel or titanium can be selected as the material of the first conductive layer 2. Next, a resist 3 is previously formed by spin coating on a portion where the first plating layer 4 is not formed. The thickness of the resist 3 can be freely set by selecting the viscosity of the resist 3, the number of rotations during spin coating, and the time. Next, a first plating layer 4 is formed on the first conductive layer 2 except for the resist 3. Then, the resist 3 is stripped and removed with a resist stripping solution (for example, acetone), and thereby the first conductive layer 2 exposed on the surface is etched and removed using nitric acid. Thus, the base conductive part 20 and the fixed conductive part 21 are formed. Next, resist 3
A portion of the silicon substrate 1 excluding the base conductive portion 20,
That is, it is formed on the insulating layer 7 and the fixed conductive portion 21 on the silicon substrate 1 while adjusting the thickness by spin coating. Next, a second conductive layer 5 is formed on the resist 3 and the base conductive part 20 by an apparatus such as EB evaporation or sputtering, and then a second plating layer 6 is formed on the second conductive layer 5. Thereafter, the resist 3 is stripped and removed with a resist stripping solution, so that the space 10 is formed. Thus space 10
The second conductive layer 5 and the second plating layer 6 formed in a beam shape on the upper side constitute the movable conductive portion 31. Then, on the movable conductive part 31, the operation part 8 for operating the movable conductive part 31 in the vertical direction of the silicon substrate 1 is placed. Either of the step of removing the resist 3 with the resist removing liquid and the step of placing the operating unit 8 on the movable conductive unit 31 may be performed first.

The case where the operating section 8 is a piezoelectric element 35 will be described (FIG. 1). The piezoelectric element 35 is attached on the movable conductive part 31 with an adhesive. When a DC voltage is applied to the piezoelectric element 35 and the second plating layer 6, the action of the piezoelectric element 35 causes the movable conductive part 31 to bend and contact in the direction of the two fixed conductive parts 21a and 21b. Therefore, the two fixed conductive portions 21a and 21b are in a state of being electrically conductive. When the application of the DC voltage is stopped, the movable conductive part 31 becomes two fixed conductive parts 21a and 21b.
Move away from Therefore, the two fixed conductive portions 21a and 21b are electrically insulated. Thus, it is configured as a semiconductor micro relay.

In the semiconductor microrelay in which the piezoelectric element 35 is mounted on the movable conductive part 31, the movable conductive part 31 is bent to the two fixed conductive parts 21a and 21b by adjusting the voltage applied to the piezoelectric element 35. Force can be increased,
Therefore, the two fixed conductive portions 21a, 21 of the movable conductive portion 31
The contact pressure with b can be increased. Therefore, a semiconductor micro relay in which the contact pressure between the movable conductive part 31 and the fixed conductive part 21 is ensured can be designed.

The case where the operating portion 8 is made of a shape memory alloy 36 will be described (FIG. 3). The shape memory alloy 36 is attached on the movable conductive part 31 with an adhesive. A means for heating the shape memory alloy 36 is required. As the heating means, for example, a diffusion resistor 40 formed by boron in the silicon substrate 1 by a semiconductor impurity diffusion step is used. This diffusion resistor 40
Forming a contact window 41 for voltage application on a part of
Further, an aluminum wiring 42 is formed in the contact window 41. When a voltage is applied to the diffusion resistor 40 through the aluminum wiring 42, the diffusion resistor 40 is heated, and heat is transmitted from the silicon substrate 1 to the second plating layer 6 of the movable conductive part 31 and the shape memory alloy 36, and The temperature of the memory alloy 36 rises. As a result, the shape memory alloy 36 is
, The movable conductive part 31 has two fixed conductive parts 21a,
21b. When the voltage application is stopped, the heating stops, the shape memory alloy 36 cools, and the movable conductive part 31
It is separated from the fixed conductive portions 21a and 21b. In this way, the movable conductive part 31 is connected to the two fixed conductive parts 21a and 21b by O.
When N is turned off, it functions as a relay.

Here, the shape memory alloy 36 may be designed or selected in accordance with the size of the space between the movable conductive part 31 and the fixed conductive part 31. For example, when the gap between the movable conductive part 31 and the fixed conductive part 21 is 10 μm, the substrate 1 in the contact part of the movable conductive part 31 with the fixed conductive part 21 is used.
What is necessary is just to select the shape memory alloy 36 whose displacement in the surface vertical direction is 10 μm or more. Therefore, the movable conductive part 31
By increasing the displacement of the movable contact portion in the vertical direction on the substrate 1 surface, the contact pressure between the movable contact portion and the contact portion on the fixed conductive portion 21 can be secured. Therefore, by using the shape memory alloy 36 for the operation layer 8, a semiconductor micro relay with a secured contact pressure can be designed.

In the case where the operating portion 8 is a thin film layer 37 having a larger thermal expansion coefficient than the second plating layer 6 according to claim 5, for example, the first plating layer 4 and the second plating layer 6 may be made of chromium (Cr). ), And the thin film layer 37 is formed of nickel (N
Consider the case formed in i) (FIG. 4). in this case,
Chromium is used for the first conductive layer and the second conductive layer. On the second plating layer 6 of Cr, a Ni / Cr layer is EB deposited,
A thin layer 37 is formed by plating a Ni layer on the Ni / Cr layer. Then, a diffusion resistor 40 is formed in advance in the silicon substrate 1 by a semiconductor impurity diffusion step of boron, and a contact window 41 is formed on a part of the diffusion resistor 40 to apply a voltage.
Is formed, and the aluminum wiring 4 is formed in the contact window 41.
2 is formed in advance. When a voltage is applied to the diffusion resistor 40 through the aluminum wiring 42, the diffusion resistor 40 is heated, and heat is transmitted from the silicon substrate 1 to the second plating layer 6 and the thin film layer 37 of the movable conductive part 31, and The temperature of the plating layer 6 and the thin film layer 37 rises. Here, the nickel of the thin film layer 37 expands more than the chromium of the second plating layer 6, so that it functions as a bimetal, and the movable conductive portion 31 flexes and contacts the two fixed conductive portions 21a and 21b. When the voltage application is stopped, the heating is stopped, and the movable conductive part 31 is separated from the two fixed conductive parts 21a and 21b as the second plating layer 6 and the thin film layer 37 of the movable conductive part 31 are cooled. Thus, the movable conductive part 31 is divided into two fixed conductive parts 21a and 21.
By turning ON and OFF to b, it functions as a relay.

In this case, the thin film layer 37 serving as the operating section 8 is
It is formed by utilizing a semiconductor process such as plating or vapor deposition. Therefore, a large number of semiconductor microrelays can be manufactured at once by a semiconductor process from one substrate. As a result, manufacturing costs are reduced.

When the second plating layer 6 is made of nickel, for example, aluminum is used for the operating portion 8. This aluminum is formed on the second plating layer 6 by sputtering.

FIG. 5 shows another example of a method for manufacturing a semiconductor microrelay. After forming the insulating layer (oxide film) 7 on the silicon substrate 1, the first conductive layer 2 is formed by EB evaporation. As a material of the first conductive layer 2, a material that can secure adhesion to a first plating layer 4 described later is used. Next, a resist 3 is previously formed by spin coating on a portion where the first plating layer 4 is not formed. Next, a first plating layer 4 is formed on the second conductive layer 2 except for the resist 3. Then, the resist 3 is stripped and removed with a resist stripping solution (for example, acetone), and thereby the first conductive layer 2 exposed on the surface is removed by etching using nitric acid to form the base conductive portion 20 and the fixed conductive portion 21. I do. Next, the first resist 25 is formed on the silicon substrate 1 and the fixed conductive portion 21 by spin coating while adjusting the thickness. Next, the second resist 26 is replaced with the first resist 25.
Form on top. However, the second resist 26 is located at a predetermined position 2 on the first resist 25 placed on the fixed conductive portion 21.
No. 7 is not formed. Next, the second conductive layer 5 is formed on the second resist 25 and the base conductive portion 20 and on the first resist 25 at a predetermined location 27 by EB evaporation, and then the second plating layer 6 is formed on the second conductive layer 5. Formed. Thereafter, the first resist 25 and the second resist 26 are stripped and removed with a resist stripping solution to form a space 28. The second conductive layer 5 and the second plating layer 6 formed like a beam on the space 28 form the movable conductive portion 32. Then, on the movable conductive part 32, the operating part 8 for operating the movable conductive part 32 in the vertical direction of the substrate 1 is placed. Either of the steps of stripping and removing the first resist 25 and the second resist 26 with the resist stripping solution and the step of placing the operating unit 8 on the movable conductive unit 32 may be performed first.

Here, a projection 50 is formed at the predetermined location 27. The protruding portion 50 serves as a movable contact portion where the movable conductive portion 32 flexes and contacts the fixed conductive portion 21 by the operating portion 8. On the other hand, the contact portion on the fixed conductive portion that comes into contact with the movable contact portion, which is the projection 50, becomes the fixed contact portion. In this manner, a semiconductor microrelay having a contact protruding can be manufactured.

[0023]

As described above, the semiconductor microrelay of the present invention has a structure in which a fixed conductive part and a movable conductive part serving as a contact switching part of a relay are formed on a semiconductor substrate by plating. Therefore, as compared with a conventional structure obtained by micro-processing a silicon substrate, it can be manufactured by a relatively simple manufacturing process without being restricted by a structural design.

[Brief description of the drawings]

FIG. 1 is a perspective view of a first example of a semiconductor micro relay according to an embodiment of the present invention.

FIG. 2 is a manufacturing process diagram showing an example of a semiconductor micro relay according to an embodiment of the present invention.

FIG. 3 is a perspective view of a second example of the semiconductor micro relay according to the embodiment of the present invention.

FIG. 4 is a perspective view of a third example of the semiconductor micro relay according to the embodiment of the present invention.

FIG. 5 is a manufacturing process diagram showing another example of the semiconductor micro relay according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 7 Insulating film 21 Fixed electrode part 31 Movable electrode part 51 Support part 8 Operating part 35 Piezoelectric element 36 Shape memory alloy 37 Thin film layer 20 Base conductive part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01H 37/52 H01H 37/52 A H01L 41/09 H01L 41/08 U 41/22 41/22 Z

Claims (7)

[Claims] 1. A semiconductor substrate, an insulating layer formed on the substrate, a fixed conductive portion formed by plating on the insulating layer, and a gap in a state electrically separated from the fixed conductive portion. And a beam-shaped movable conductive portion formed by plating so as to face the upper portion, and rises above the fixed conductive portion and is connected to a part of the movable conductive portion to physically support the movable conductive portion with respect to the substrate. A supporting portion, and an operating portion formed on the movable conductive portion and bending a portion of the movable conductive portion in the vertical direction of the substrate surface of the semiconductor substrate so as to electrically conduct to the fixed conductive portion. A semiconductor micro relay. 2. The semiconductor microrelay according to claim 1, wherein a contact portion that is electrically connected to the fixed conductive portion when the movable conductive portion is bent is in contact with the fixed conductive portion. 3. The semiconductor micro-relay according to claim 1, wherein said operating portion is a piezoelectric element. 4. The semiconductor microrelay according to claim 1, wherein said operating portion is made of a shape memory alloy, and further comprising heating means for heating said movable conductive portion. 5. The semiconductor according to claim 1, wherein said operating portion is a thin film layer having a larger thermal expansion coefficient than said movable conductive portion, and further comprises heating means for heating said movable conductive portion. Micro relay. 6. A first plating step of forming a fixed conductive portion and a base conductive portion electrically separated from the fixed conductive portion on an insulating layer provided on a semiconductor substrate by plating, and the base conductive portion. Except for the fixed conductive portion and a resist forming step of loading a resist on a separation portion between the fixed conductive portion and the base conductive portion, and by plating the resist and the base conductive portion through the resist, A second plating step of forming a movable conductive portion facing the fixed conductive portion and forming a support portion for supporting the movable conductive portion by stacking a plating layer on the base conductive portion, and removing the resist. Forming a gap portion, and stacking and forming on the movable conductive portion an operating portion for bending the movable conductive portion toward the fixed conductive portion in the vertical direction of the substrate surface. Manufacturing method of semiconductor micro relay. 7. The resist forming step, wherein a concave portion is provided at a position corresponding to a contact point of the movable conductive portion on an upper surface of the stacked resist layer.
A manufacturing method of the semiconductor microrelay described in the above.