JP4601528B2 - Manufacturing method of micromachining switch using pull-up type contact pad - Google Patents

Description

  The present invention relates to a method of manufacturing a semiconductor switch used in various communication systems, and more particularly to a method of manufacturing a micromachining switch using a pull-up type electrostatic electrode and a movable contact pad using a micromachining technique.

A semiconductor switch manufactured using conventional micromachining technology applies static electricity generated by applying a high DC voltage to a dielectric thin film such as silicon oxide (SiO ₂ ) or silicon nitride (Si ₃ N ₄ ). The switch is actuated by a contact means such as a cantilever or a contact pad that acts as a signal path with a specific force repeatedly shorting (on) and opening (off) the signal transmission line.

  1 and 2 show an example of a semiconductor switch using a micromachining technology having a conventional pull-down cantilever. FIG. 1 shows a parallel micromachining switch, and FIG. 2 shows a serial micromachining switch. In FIG. 2a, a signal transmission line 11 and a DC voltage application pad 13 for driving the cantilever 12 are separately configured, and in FIG. 2b, the signal transmission line and the DC voltage application pad 14 are configured on the same line. Yes. Here, 15 is a pull-down electrode, 16 is a contact region, and 17 is an anchor.

  A conventional pull-down type micromachining switch manufactured by using such a conventional technique has a high isolation characteristic between a short circuit and an open circuit, and therefore has a low signal loss. It can be used in a wide frequency range over a frequency region of a millimeter wave band of 30 GHz or more.

  The conventional pull-down micromachining switch shown in FIGS. 1 and 2 applies a DC voltage so as to generate an electrostatic force greater than the elastic force of the metal constituting the cantilever to short-circuit the signal transmission line and the cantilever. The cantilever is restored and opened by the elastic force of the metal.

  Semiconductor switches developed using existing micromachining technology must apply a high DC voltage of 20V or higher to pull the metal that forms the cantilever in order to short-circuit the cantilever to the signal transmission line. Therefore, in order to be applied to the communication system, there is a problem that another circuit for boosting the voltage for driving the system is required.

  Further, since the method of opening to the signal transmission line requires a recovery force by the elasticity of the metal constituting the cantilever, there is a problem that the use time is short and the reliability is low due to the deformation of the cantilever.

  A conventional micromachining switch uses a pull-up type electrostatic force electrode and a cantilever, and can be driven with a low DC voltage of 5 V or less so that it can be used in a communication system, and cannot be used semipermanently.

  The micromachine switch according to the present invention uses a contact pad instead of a pull-up type electrostatic force electrode and a cantilever.

In order to achieve the above object, in the present invention, in order to prevent signal transmission loss in the silicon substrate 21, a first step of laminating a silicon oxide film or nitride film 22 on both surfaces of the substrate; the pull-up electrode 24 electrostatic force generation dielectric thin film 25 for the contact pads 27 driven on; the laminated substrate lower signal Goden transmission line 23 and the pull-up electrode 24 second stage metal wiring process for forming A third step of stacking using a chemical vapor deposition method (CVD) and etching into a predetermined pattern ; a contact pad 27 using a plating method, and a stable contact pad 27 on the transmission line 23 the contact pads 27 and the signal to prevent the loss of the contact pads 27; the fourth stage of the contact pad 27 and a guard pawl 26 for operation embodied form in a form which is interposed Metal in order to apply a DC voltage to the weigh measurement of the contact pads 27 of the contact pads 27; the fifth step of forming a groove in the cover glass plate 28 for maintaining a constant distance between the feed line 23 the contact with the weight measurement of the contact pad 27; sixth step to form an extended transmission line 29 by the wiring step; seventh stage using both poles bonding method for bonding the silicon substrate 21 and the glass plate 28 A pull-up type including an eighth stage which is a silicon etching process in which driving of the measurement pad and the DC voltage application pad formed on the silicon substrate 21 to apply a DC voltage to the pad 27 is turned off. Manufactured using a manufacturing method for micromachining switches that use contact pads, the contact pads are pulled up, and the contact pads and transmission lines are short-circuited at a low DC voltage. So, to provide a manufacturing method of micromachining switch using a pull-up type contact pad structure which opens by utilizing gravity by the weight of the contact pads to constitute a contact pad with a thick metal layer.

The manufacturing method of the micromachining switch using the pull-up type contact pad is a first step of laminating a silicon oxide film or a nitride film 22 on both sides of the substrate in order to prevent signal transmission loss in the silicon substrate 21; electrostatic force for the contact pad drive on the pull-up electrode 24; the second phase of the film or Shin Goden the substrate lower nitride film 22 are laminated transmission lines 23 and the pull-up electrode 24 metal wiring process for forming A third stage of depositing a dielectric thin film 25 for generation using a chemical vapor deposition method (CVD) and etching it into a predetermined pattern ; a contact pad 27 using a plating method and the contact on the transmission line 23 fourth step the contact pad 27 and a guard pawl 26 for stable operation embodying the pad 27 is formed in a form that is interposed; heritage of the contact pads 27 Fifth stage forming grooves in the cover glass plate 28 for maintaining a constant distance between the contact pads 27 and the signal transmission line 23 to prevent; measurement of weight and the contact pads 27 of the contact pads 27 stage 7 joined with the glass plate 28 by using both poles bonding method of the silicon substrate 21; sixth step of forming an extended transmission line 29 to the glass by a metal wiring process for applying a DC voltage to the weight of measuring the open driving of the contact DC voltage applying pad for measurement pad formed on an upper portion of the silicon substrate 21 in order to apply a DC voltage to the pads 27 of the contact pads 27 (off) to silicon etch It includes an eighth stage which is a process.

  The micromachining switch using the pull-up type contact pad of the present invention has a high short-circuit / open-isolation characteristic, and does not require a circuit for boosting the drive voltage inside the communication system with a low drive voltage. Can be reduced in size.

  Further, since the metal constituting the contact pad is not deformed during driving, there is almost no change in characteristics even after long-term use, and there is an effect that it can be used semipermanently.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a characteristic configuration, operation and effect of the present invention will be described in detail with reference to the accompanying drawings.

  1 and 2 show an example of a semiconductor switch using a micromachining technology having a conventional pull-down cantilever. FIG. 1 shows a parallel type micromachining switch, FIG. 2 shows a series type micromachining switch, and FIG. 3 sequentially shows the steps of the micromachining switch using the pull-down contact pad of the present invention. FIG.

  3A is a diagram showing a silicon substrate 21, and FIG. 3B is a diagram showing both sides of the silicon substrate 21 of FIG. 3A to prevent signal loss on the substrate, and both sides of the substrate to prevent signal transmission loss on the silicon substrate. FIG. 6 is a diagram illustrating a first stage in which a silicon oxide film or a nitride film 22 is stacked.

Since a general silicon substrate has a low resistance due to a high impurity concentration, when a signal is transmitted to a transmission line directly formed on the silicon substrate, a signal loss occurs in the substrate. For the reasons described above, a silicon oxide film or a nitride film can be formed on both sides of the silicon substrate before the metal wiring forming step to prevent signal loss on the substrate. Silicon oxide (SiO ₂ ) is used as the silicon oxide film used in the first stage, and silicon nitride (Si ₃ N ₄ ) is used as a typical nitride film. These silicon oxide and silicon nitride are laminated using a method such as thermal oxidation or CVD (chemical vapor deposition).

  FIG. 3c is a diagram illustrating a second stage of a metal wiring process for forming a signal transmission line 23 and a pull-down electrode 24 under a substrate on which a silicon oxide film or a nitride film is laminated. After forming a pattern using a printing method (silk-screen printing) and a photosensitive thin film (patterning), a metal wiring is formed using a method such as sputtering or vapor deposition.

FIG. 3d shows a third step of laminating and etching the electrostatic force generating dielectric thin film 25 for driving the contact pad. Silicon oxide and silicon nitride are used as the dielectric thin film for generating electrostatic force. These dielectric thin films are easily stacked using a chemical vapor deposition method and can be easily etched into a desired pattern. As the etching method, dry etching using gas and plasma is mainly used, and gases used for etching are sulfur hexafluoride (SF ₆ ), trifluoride methane (CHF ₃ ), and hexafluoroethane (C _2). Fluorine series gases such as F ₆ ) and silicon tetrafluoride (SiF ₄ ) are used. When wet etching is used, a hydrofluoric acid (HF) series etching solution is used. The etching process is performed for as long a time as possible so that the silicon oxide film or the nitride film is etched in the remaining part of the lower part of the substrate except the part where the metal wiring is formed in the dielectric thin film etching process for generating electrostatic force. The portion from which the oxide film or nitride film has been removed becomes a portion to be bonded to the glass plate in the seventh step bipolar bonding step.

  FIG. 3e shows a fourth step of forming a contact pad 27 and a guard pole 26 for realizing stable operation of the contact pad using a plating method. The contact pad is a pull-up type that is not a conventional pull-down type. To be produced. When manufactured as a pull-up type, it has the following characteristics.

  First, the contact pad can be driven by a low DC voltage. In the conventional pull-down contact pad, the contact pad is not driven unless an electrostatic force greater than the elastic force of the metal constituting the pull-down contact pad is applied. Driving voltage is low because electrostatic force more than gravity due to the height is required.

  Second, the contact pad is not attached to the substrate like the existing switch, and has a structure independent of the substrate. Thereby, even if it uses for a long time, a deformation | transformation of a contact pad does not arise but it can be used semipermanently.

  Third, the shorting and opening of the contact pad depends on the weight of the contact pad. If the weight is light, the driving voltage of the contact pad is low, but it is difficult to open it. If the weight is heavy, the opening is easy, but the driving voltage is high. For this purpose, the contact pad has a metal layer structure with a thickness that can secure a weight for short-circuiting and opening the signal transmission line.

  FIG. 3f shows a fifth step of forming a groove in the cover glass plate 28 to prevent the contact pad from being lost and to maintain a constant distance between the contact pad and the signal transmission line. Glass etching is performed using hydrofluoric acid, and the etching depth is determined by calculating the thickness of the contact pad and the distance between the contact pads.

  FIG. 3g shows a sixth step of forming an extended transmission line 29 on the glass by a metal wiring process for measurement and application of a DC voltage. A pattern using a silk screen printing method (stencil printing method) and a photosensitive thin film is used. Then, an extended electrode is formed using a method such as sputtering or vapor deposition.

  FIG. 3h is a view illustrating a seventh stage of bonding the glass plate and the silicon substrate using a bipolar bonding method after pattern alignment between the glass plate and the silicon substrate. The bipolar bonding method is a kind of bonding method in which a silicon substrate or a semiconductor substrate such as gallium arsenide (GaAs) is attached to the same semiconductor substrate or another substrate such as glass. In the present invention, the silicon substrate and the glass are bonded to each other by bipolar bonding in order to support the contact pad and maintain a constant distance between the contact pad and the contact pad.

FIG. 3i is a diagram illustrating an eighth stage of a silicon etching process for opening the measurement pad and the DC voltage application pad in order to apply the measurement and the DC voltage. After pattern alignment, only silicon is etched to have high selectivity using a lie or wet etching method. Dry etching is based on fluorine series such as sulfur hexafluoride (SF ₆ ), trifluoride methane (CHF ₃ ), ethane hexafluoride (C ₂ F ₆ ) and silicon tetrafluoride (SiF ₄ ) or chlorine (Cl ₂ ). This is done using chlorine series gases such as boron trichloride (BCl ₃ ) and silicon tetrachloride (SiCl ₄ ). The wet etching is performed using an anisotropic etching solution such as potassium hydroxide (KOH) or TMAH (trimethyl ammonium hydroxide). The dry etching method can obtain a substantially vertical interface as compared with the wet etching method, but has a problem that a rough interface appears as compared with the wet etching method.

  FIG. 4 is a view showing a structure of a micromachining switch using a pull-up type contact pad according to the present invention. The contact pad 27 has a structure independent of the silicon substrate 21.

  In FIG. 4, a signal is transmitted by an extended transmission line, a signal transmission line, and a contact pad when short-circuited. The contact pad is driven by applying a current voltage.

This is a parallel micromachining switch using a conventional pull-down cantilever. It is external appearance explanatory drawing which shows the serial type micromachining switch using the conventional pull-down type cantilever. It is a cross-sectional explanatory drawing of the micromachining switch of FIG. It is sectional explanatory drawing which shows the silicon substrate of the process explanatory drawing which showed the process of the micromachining switch using the pull-up type contact pad of this invention sequentially. It is sectional explanatory drawing which shows the state which laminated | stacked the silicon nitride on both surfaces of the silicon substrate of the process explanatory drawing which showed the process of the micromachining switch using the pull-up type contact pad of this invention sequentially. It is sectional explanatory drawing which showed formation of the signal transmission line of the process explanatory drawing which showed the process of the micromachining switch using the pull-up type contact pad of this invention in order, and the pull-up type electrode wiring. It is sectional explanatory drawing which showed the dielectric thin film lamination for contact pad drive of the process explanatory drawing which showed the process of the micromachining switch using the pull-up type contact pad of this invention in order, and etching. It is sectional explanatory drawing which showed formation of the contact pad and guard pole of the process explanatory drawing which showed the process of the micromachining switch using the pull-up type contact pad of this invention sequentially. It is sectional explanatory drawing which showed formation of the groove | channel for a contact pad cover in the glass plate of the process explanatory drawing which showed the process of the micromachining switch using the pull-up type contact pad of this invention sequentially. It is sectional explanatory drawing which showed formation of the extended transmission line in the glass plate of the process explanatory drawing which showed the process of the micromachining switch using the pull-up type contact pad of this invention sequentially. It is sectional explanatory drawing which showed joining of the silicon substrate and glass by bipolar | dipolar joining of the process explanatory drawing which showed the process of the micromachining switch using the pull-up type contact pad of this invention sequentially. It is sectional explanatory drawing which showed the silicon etching for the measurement of the process explanatory drawing which showed the process of the micromachining switch using the pull-up type contact pad of this invention in order, and the pad part for DC voltage application. FIG. 4 is a structural diagram of a micromachining switch using the pull-up type contact pad of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11, 23 Signal transmission line 12 Cantilever 13, 14 DC voltage application pad 15 Pull-down electrode 16 Contact region 17 Anchor 21 Silicon substrate 22 Silicon oxide film or nitride film 24 Pull-up electrode 25 Dielectric thin film for generating electrostatic force 26 Guard Paul 27 Contact pad 28 Glass plate 29 Extended transmission line

Claims (2)

A first step of laminating a silicon oxide film or a nitride film (22) on both sides of the substrate to prevent signal transmission loss on the silicon substrate (21);
The second step of the metal wiring process for forming a silicon oxide film or a nitride film (22) signal to the substrate lower portion which are stacked Goden feed line (23) to pull up electrode (24),
A third step of laminating a dielectric thin film (25) for generating an electrostatic force for driving a contact pad on the pull-up electrode (24) using a chemical vapor deposition method (CVD), and etching into a predetermined pattern ;
Contact utilizing plating method pads (27) and said signal transmission line guard Paul (26) for the stable operation embodying the contact pads on the (23) (27) and said contact pads (27) A fourth step of forming in an intervening form ,
Fifth step of forming grooves in the cover glass plate (28) for maintaining a constant distance between the contact pads to prevent loss of the contact pads (27) (27) and the signal transmission line (23),
A sixth step of forming an extended transmission line (29) on the glass by measuring the weight of the contact pad (27) and a metal wiring process for applying a DC voltage to the contact pad (27) ;
Seventh step of bonding the silicon substrate and the glass plate by using the two electrode joining method (28) (21), and
In order to measure the weight of the contact pad (27) and to apply a DC voltage to the contact pad (27), the measurement pad and the DC voltage application pad formed on the silicon substrate (21) are driven . A method of manufacturing a micromachining switch using a pull-up type contact pad, comprising an eighth step of opening (off) . 2. The micro of the pull-up type contact pad according to claim 1, wherein the contact pad of the fourth step has a structure of a metal layer having a thickness capable of securing a weight for shorting and opening the signal line. Machining switch manufacturing method.

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