KR20030077791A - Micro-actuator fabrication method - Google Patents

Abstract

PURPOSE: A method for fabricating a micro-sized driving device is provided to drive the micro-sized driving device with low operating voltage by allowing electrodes having a comb shape to have fine interval. CONSTITUTION: A substrate is firstly prepared. Then, a first oxide layer, a first silicon layer, a second oxide layer, a nitride layer and a third oxide layer are sequentially deposited on the substrate. A first electrode pattern is formed on the third oxide layer by using a photosensitive film. The third oxide layer, the nitride layer, the second oxide layer and the first silicon layer are etched along the first electrode pattern in order to expose the first oxide layer, thereby obtaining a first electrode having a plurality of fingers. An oxide layer is formed at a lateral portion of the first electrode. Then, a second electrode is formed by etching a fourth oxide layer and a second silicon layer formed on the second silicon layer. After that, the first oxide layer, the second oxide layer, the lateral oxide layer, the fourth oxide layer and the nitride layer are removed, thereby achieving a micro-sized driving device.

Description

Micro actuator manufacturing method {Micro-actuator fabrication method}

The present invention relates to a micro driver manufacturing method using an electrostatic force, and more particularly, to a micro driver using an electrostatic force to form a fine gap between electrodes.

In microelectromechanical systems (hereinafter referred to as MEMS) using semiconductor technology, the electrostatic force that is commonly used is proportional to the voltage and the working area and inversely proportional to the distance between electrodes. Increasing the applied voltage to improve the electrostatic force has the disadvantage of creating a high cost. Therefore, in the MEMS field, the focus is on the method of increasing the electrostatic force by increasing the area of electrostatic force by using a wafer aspect area to have a high aspect ratio. However, this has the disadvantage of lowering productivity since the entire wafer must be processed.

In recent years, research on a method of reducing the gap between electrodes has been actively conducted in order to obtain a greater electrostatic force due to a change in relative capacitance. Here, the driver is made of a comb shape having a plurality of fingers in order to reduce the distance between the electrodes, when the two comb-shaped electrodes face each other to form a shape that is engaged. The comb-shaped actuator is manufactured by forming a wide gap and a narrow gap through a thermal oxidation process of the polycrystalline silicon film, and then operating the fingers after placing the fingers placed at a wide gap in a narrow gap. The process of placing the fingers at between the fingers with a narrow spacing is added, and the operating characteristics are nonlinear. Another method is to fabricate a comb-shaped driver having a slightly wider gap with a polycrystalline silicon film, and then to deposit a polycrystalline silicon film to narrow the wide gap. In this method, uniformly depositing polycrystalline silicon between each finger to obtain a uniform electrostatic force only when the distance is constant, it is very difficult to uniformly deposit polycrystalline silicon.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a micro driver manufacturing method having a comb shape having low operating voltage characteristics.

1 is a block diagram illustrating a method of manufacturing a micro driver according to the present invention;

2A to 2C are schematic diagrams for explaining a step of forming a first electrode on a substrate in an embodiment of a method of manufacturing a micro driver according to the present invention;

3 is a perspective view for explaining a step of forming a side oxide film on the side of the first electrode in the embodiment according to the present invention,

4A to 4F are schematic views for explaining a step of forming a second electrode on a substrate on which a first electrode is formed in an embodiment according to the present invention;

5 is a schematic view for explaining a step of completing the micro driver in the embodiment according to the present invention.

The micro-driver according to the present invention for achieving the technical problem is composed of a comb-shaped first electrode and a second electrode having a plurality of fingers, the second electrode corresponding to each of the fingers of the first electrode In the micro-driver manufacturing method comprising a shape in which each of the fingers of the engagement,

Providing a substrate; Sequentially depositing a first oxide film, a first silicon film, a second oxide film, a nitride film, and a third oxide film on the substrate, and then forming a pattern of the first electrode on the third oxide film using a photosensitive film. Forming the first electrode having a plurality of fingers by etching the third oxide film, the nitride film, the second oxide film, and the first silicon film to expose the first oxide film according to a pattern of one electrode; Forming a side oxide film on a side surface of the first electrode exposed by the etching; Forming a second silicon film to a thickness of the first silicon film on the exposed region of the first oxide film, removing the third oxide film on the first electrode, and forming a fourth oxide film on the second silicon film Next, a pattern of the second electrode is formed on the fourth oxide film using a photoresist film, and the fourth oxide film and the second silicon film are etched according to the pattern of the second electrode to expose the first oxide film. Forming an electrode; And removing the first oxide film, the second oxide film, the side oxide film, the fourth oxide film, and the nitride film to complete the micro driver.

In this case, the first silicon film and the second silicon film are made of a polycrystalline silicon film, and the side oxide film or the fourth oxide film is formed by a thermal oxidation method.

Further, in the forming of the second electrode, each of the fingers of the first electrode may be etched to provide a space for the first electrode to move horizontally.

Further, the forming of the second electrode may include: forming the second silicon film on a region where the first oxide film is exposed, depositing the second silicon film to a thickness greater than or equal to the thickness of the first silicon film, and then chemically or It is preferable to form the same as the thickness of the first silicon film by mechanical polishing.

Hereinafter, a method of manufacturing a micro driver having a comb shape according to the present invention will be described in detail with reference to the drawings.

1 is a block diagram illustrating a method of manufacturing a micro driver according to the present invention.

Referring to FIG. 1, the method of manufacturing a micro driver according to the present invention includes preparing a substrate, forming a first electrode, forming a side oxide film, forming a second electrode, and completing a micro driver. The steps are carried out sequentially.

Next, an embodiment sequentially progressed to each step of the micro driver manufacturing method according to the present invention will be described in detail with reference to the drawings.

EXAMPLE

2A to 2C are schematic views for explaining a step of forming a first electrode on a substrate in the embodiment of the method of manufacturing a micro driver according to the present invention. 2A is a perspective view illustrating a substrate in which a first oxide film, a first silicon film, a second oxide film, a nitride film, and a third oxide film are sequentially stacked on the prepared substrate, and FIG. 2B is on the substrate according to FIG. 2A. FIG. 2C is a perspective view illustrating a pattern formed in the shape of the first electrode, and FIG. 2C is a perspective view illustrating the first electrode etched into the pattern according to FIG. 2B.

2A to 2C, first, a silicon substrate 100 is prepared, and then the first oxide film 210 is used as a sacrificial layer for floating of electrodes formed on the silicon substrate 100 by chemical vapor deposition or the like. Deposit.

Next, a polycrystalline silicon film is deposited as the first silicon film 300 for forming the main structure of the first electrode on the substrate 100 on which the first oxide film 210 is deposited. Then, the second oxide film 220, the nitride film 400, and the third oxide film 230 are sequentially stacked by a method such as chemical vapor deposition.

Next, a pattern of the first electrode is formed on the third oxide film 230 in a comb shape having a plurality of fingers as a photosensitive film.

Subsequently, the second oxide film 220, the nitride film 400, the third oxide film 230, and the first silicon film 300 sequentially stacked are sequentially etched according to the pattern of the first electrode. And the second oxide film 220, the nitride film 400, the third oxide film 230, and the first silicon film 300 remaining by isotropic etching so that the first oxide film 210 is exposed. The electrodes are sequentially stacked in the pattern shape of the electrode.

3 is a perspective view for explaining a step of forming a side oxide film on the side of the first electrode in the embodiment according to the present invention.

Referring to FIG. 3, as described above, the first silicon film, the second oxide film 220, the nitride film 400, and the third oxide film 230 are formed on the substrate 100 on which the first oxide film 210 is deposited. It is etched into the shape of one electrode. Next, a side oxide film 240 is formed by a thermal oxidation method to protect a side portion of the first silicon film as the first electrode exposed by the vertical etching and to form a fine gap between the electrode and the electrode. Here, since the oxide film by the thermal oxidation method is not formed in the portion where the third oxide film 230 and the nitride film 400 are formed, the oxide film is formed only at the side portion where the first silicon film is exposed.

4A to 4F are schematic diagrams for explaining a step of forming a second electrode on a substrate on which a first electrode is formed in an embodiment according to the present invention. 4A is a perspective view illustrating the formation of the second silicon in the same thickness as the first silicon, and FIG. 4B illustrates a partial deposition of the fourth oxide film on the substrate according to FIG. 4A using the nitride film as an anti-oxidation film. 4C is a perspective view illustrating the formation of the pattern of the second electrode on the fourth oxide film according to FIG. 4B, and FIG. 4D is a view illustrating the second electrode etched in the pattern according to FIG. 4C. 4E is a perspective view illustrating a photosensitive film phenomenon for forming a horizontal moving space of the first electrode in the pattern according to FIG. 4D, and FIG. 4F (1) is an etched horizontal line of the first electrode in FIG. 4E. 4F is a plan view illustrating that a horizontal movement space of the first electrode is formed by etching according to FIG. 4E.

Referring to FIGS. 4A to 4F, a polycrystalline silicon film is deposited thicker than the first silicon film as the second silicon film 310 on the first oxide film 210 exposed on the substrate 100 as described above. The above-described side oxide film 240 is chemically or mechanically polished until it is exposed to be equal to the thickness of the first silicon film. At this time, since it is difficult to form the second silicon film 310 to the thickness of the first silicon film only by deposition, it is easier to deposit and polish the second silicon film 310 thickly.

Next, the third oxide film 230 formed in the pattern of the first electrode is removed, and the fourth oxide film 250 is formed on the polished second silicon film 310 as an etch stop layer by a thermal oxidation method. In this case, when the third oxide film 230 is removed, the nitride film 400 is exposed, and since the oxide film due to thermal oxidation is not formed on the nitride film 400, the thermal oxide film is formed only in the portion except for the first electrode part.

Then, on the fourth oxide film 250, a pattern of a second electrode having a shape in which each of the fingers of the first electrode and each of its own fingers corresponding to each other is formed as a photosensitive film is formed as an etch stop layer. The fourth oxide film 250 remaining by vertical etching according to the pattern of the second electrode using the first electrode pattern-shaped nitride film 400 and the fourth oxide film 250 and horizontally etched to expose the first oxide film 210. And the second silicon film 310 are sequentially stacked in the pattern shape of the second electrode. At this time, in order to form a space in which the first electrode can move, the photoresist film 60 is developed on the fingers of the first electrode as shown in FIG. 4E, and the nitride film 400 and the fourth oxide film 250 are etched away. A portion of the fingers is horizontally and vertically etched to form a second electrode.

5 is a schematic view for explaining a step of completing the micro driver in the embodiment according to the present invention. 5 (1) is a perspective view showing the micro driver completed according to the present embodiment, and FIG. 5 (2) is a plan view showing the micro driver completed according to the present embodiment.

Referring to FIG. 5, by removing the nitride film, the first oxide film, the second oxide film, the fourth oxide film, and the side oxide film on the first silicon film 300 and the second silicon film 310 by a wet or dry etching method, A comb-shaped driver capable of freely horizontally moving the first electrode formed of the first silicon film 300 and the second electrode formed of the second silicon film 310 with a fine interval equal to the thickness of the side oxide film is completed. In this case, when the first oxide film, which is a sacrificial layer, is removed by horizontal etching, the respective electrodes float on the substrate 100. Here, when the side oxide film is vertically etched, it is preferable to appropriately leave the anchor portion.

As described above, in the present embodiment, polycrystalline silicon is deposited as the first silicon film and the second silicon film to form the first electrode and the second electrode. However, the present invention is not limited thereto, and may be deposited with single crystal silicon.

As described above, according to the method of manufacturing the micro driver of the present invention, the comb-shaped electrodes have finer spacings by only chemical or mechanical etching by depositing oxide and nitride films, thereby generating greater electrostatic force, thereby driving at low operating voltages. It works.

In addition, since the micro driver using such a low operating voltage can be obtained by a simpler process, there is an effect that can contribute to the development of the MEMS field.

The present invention is not limited to the above embodiments, and it is apparent that many modifications are possible by those skilled in the art within the technical spirit of the present invention.

Claims (5)

In the micro-driver manufacturing method comprising a comb-shaped first electrode and a second electrode having a plurality of fingers, wherein each of the fingers of the first electrode and the fingers of the second electrode corresponding to each other is in engagement with each other. In Providing a substrate; Sequentially depositing a first oxide film, a first silicon film, a second oxide film, a nitride film, and a third oxide film on the substrate, and then forming a pattern of the first electrode on the third oxide film using a photosensitive film. Forming the first electrode having a plurality of fingers by etching the third oxide film, the nitride film, the second oxide film, and the first silicon film to expose the first oxide film according to a pattern of one electrode; Forming a side oxide film on a side surface of the first electrode exposed by the etching; Forming a second silicon film to a thickness of the first silicon film on the exposed region of the first oxide film, removing the third oxide film on the first electrode, and forming a fourth oxide film on the second silicon film Next, a pattern of the second electrode is formed on the fourth oxide film using a photoresist film, and the fourth oxide film and the second silicon film are etched according to the pattern of the second electrode to expose the first oxide film. Forming an electrode; And removing the first oxide film, the second oxide film, the side oxide film, the fourth oxide film, and the nitride film to complete a micro driver. The method of claim 1, wherein the first silicon film and the second silicon film are made of a polycrystalline silicon film. The method of claim 1, wherein the side oxide film or the fourth oxide film is formed by a thermal oxidation method. The method of claim 1, wherein the forming of the second electrode comprises etching a finger of the first electrode to provide a space in which the first electrode can be horizontally moved. The method of claim 1, wherein the forming of the second electrode comprises depositing the second silicon film to a thickness greater than or equal to the thickness of the first silicon film when the second silicon film is formed on a region where the first oxide film is exposed. And chemically or mechanically polishing the same to form a thickness of the first silicon film.