KR20040046544A - Method for manufacturing acoustic transducer - Google Patents

Abstract

PURPOSE: A method for fabricating a sound detection device is provided to reduce a fabricating cost by forming a metallic top electrode instead of a thick top electrode including polycrystalline silicon and a nitride oxide layer. CONSTITUTION: A silicon oxide layer(110) and a silicon nitride layer(120) are sequentially formed on a top part and a bottom part of a silicon substrate(100), respectively. A bottom electrode(131) is formed on a part of the silicon nitride layer. A first photoresist layer is formed on the silicon nitride layer and the lower electrode. A plurality of grooves are formed by etching the first photoresist layer. A seed layer is formed on the first photoresist layer and the grooves. The second photoresist layer is formed on the seed layer. A plurality of groove regions are formed by removing partially the second photoresist layer. A plurality of small grooves are formed on the bottom electrode. A metal layer is deposited on the grooves and the small grooves. A membrane is formed by etching sequentially the silicon nitride layer, the silicon oxide layer, and the silicon substrate. A top electrode(190) having a plurality of air holes(191) is formed by removing partially the first and the second photoresist layers and the seed layer.

Description

Method for manufacturing acoustic sensing device

The present invention relates to a method of manufacturing an acoustic sensing device, and more particularly, to form a metal layer through a plating process without forming a thick upper electrode, thereby reducing manufacturing costs, and manufactured by MEMS (Micro Electro Mechanical System) process technology. The present invention relates to a method of manufacturing an acoustic sensing device capable of realizing an ultra-small device.

In general, with the rapid development of telecommunications, microphones for converting voice into electrical signals are becoming smaller.

The microphone is mainly used in the condenser type to change the distance between the diaphragm and the fixed electrode due to the sound transmitted to the diaphragm, thereby changing the capacitance between the lower electrode and the fixed electrode formed on the diaphragm into an electrical signal.

The condenser microphone according to the prior art uses various methods such as a diaphragm, a counter electrode, and a signal processing printed circuit board, respectively, to manufacture and then assemble them.

In order to improve this, parts of the acoustic sensing elements such as the diaphragm and the electrode were all manufactured on one substrate using a semiconductor process.

The manufacturing of the acoustic sensing device by the semiconductor process serves as a structure to fix the polyimide to the diaphragm and the upper electrode, and to raise the polycrystalline silicon or silicon nitride film using aluminum, silicon oxide, and porous silicon film as a sacrificial layer, and polycrystalline Various methods have been attempted such as forming an upper electrode with a silicon or silicon nitride film and using a single crystal silicon film as a diaphragm.

However, when organic materials such as polyimide are used as a structure, the sensitivity is changed due to changes in external environment such as temperature and humidity, and when the aluminum, silicon oxide, or porous silicon is used as a sacrificial layer, the etchant has a strong corrosiveness. Therefore, corrosion of other parts and bonding of the upper and lower electrodes occur, which causes a problem that the yield is lowered.

In addition, when the upper electrode is made of polycrystalline silicon, silicon nitride film, etc., the upper electrode must be much thicker than the thickness of the diaphragm to increase acoustic efficiency, but this process increases the manufacturing cost of the microphone because the process time is very long and expensive. do.

Accordingly, the present invention has been made to solve the above problems, it is possible to reduce the manufacturing cost by forming a metal layer by plating when forming a thick upper electrode, by using a MEMS (Micro Electro Mechanical System) process technology It is an object of the present invention to provide a method of manufacturing an acoustic sensing device capable of realizing an ultra-small device.

A preferred aspect for achieving the above object of the present invention comprises a first step of sequentially forming a silicon oxide film and a silicon nitride film on the surface of the silicon substrate;

Forming a lower electrode of the acoustic sensing device in a portion of the upper portion of the silicon nitride film on the silicon substrate;

A third step of forming a first photoresist layer surrounding the silicon nitride layer and the lower electrode, and etching the first photoresist layer to form a plurality of grooves in a portion spaced apart from the lower electrode;

A fourth step of forming a seed layer formed of a metal surrounding the first photoresist layer and the plurality of grooves;

A second photoresist layer is formed on the seed layer, and a portion of the second photoresist layer is removed to form the plurality of groove regions for forming a support part and an electrode pad of the upper electrode, and the upper side of the lower electrode spaced apart from the plurality of grooves. A fifth step of forming a plurality of small grooves for forming air inlets of the acoustic sensing element in the chamber;

A sixth step of plating a metal layer on the plurality of grooves and the plurality of small grooves;

Sequentially removing portions of the silicon nitride film, the silicon oxide film, and the silicon substrate under the silicon substrate, and etching the portions to form a membrane in which the silicon oxide film and the silicon nitride film under the lower electrode are floated. A seventh step;

There is provided a manufacturing method of an acoustic sensing device comprising an eighth step of removing a portion of the first and second photoresist layer and the seed layer to have a plurality of air inlets, and to form a floating upper electrode supported by the plurality of support parts. do.

1A to 1J are manufacturing process diagrams of an acoustic sensing device according to the present invention.

2 is a plan view of FIG. 1J.

<Description of the symbols for the main parts of the drawings>

100 silicon substrate 110111 silicon oxide film

120,121 silicon nitride film 130,180 metal layer

131,320: lower electrode 140,170: photoresist layer

150,175,176: Groove 160: Seed layer

190,310: upper electrode 191,311: air inlet

140, 170 photoresist layer 400 substrate

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

1A to 1J are manufacturing process diagrams of an acoustic sensing device according to the present invention. First, silicon oxide films 110 and 111 and silicon nitride films 120 and 121 are sequentially formed on a surface of a silicon substrate 100 (FIG. 1A).

Subsequently, the metal layer 130 is formed on the silicon nitride film 120 on the silicon substrate 100 (FIG. 1B), and the metal layer 130 is etched to form the lower electrode 131 of the acoustic sensing device. Alternatively, the lower electrode is formed by forming a metal layer only in a predetermined region by a lift-off or shadow mask or the like (FIG. 1C).

Subsequently, the metal layer 130 is etched to surround the exposed silicon nitride film 120 and the lower electrode 131 to form a first photoresist layer 140 (FIG. 1D), and the first photoresist layer 140. ) Is formed to form a plurality of recesses 150 in a portion spaced apart from the lower electrode 131.

Next, a seed layer 160 made of a metal is formed to surround the first photoresist layer 140 and the plurality of grooves 150 (FIG. 1F), and a first layer is formed on the seed layer 160. After the second photoresist layer 170 is formed, a portion of the second photoresist layer 170 is removed to form regions of the plurality of recesses 176 for forming a support of the acoustic sensing element. A plurality of small grooves 175 are formed on the lower electrode 131 spaced apart from the grooves 150 to form air inlets of the acoustic sensing element.

Subsequently, the metal layer 180 is plated on the plurality of grooves 176 and the plurality of small grooves 175 (FIG. 1H).

Subsequently, the silicon nitride film 121, the silicon oxide film 111, and a part of the silicon substrate 100 under the silicon substrate 100 are sequentially removed (FIG. 1I).

At this time, the silicon oxide film 110 and the silicon nitride film 121 below the lower electrode 131 are floated to form a membrane.

Finally, when the first and second photoresist layers 140 and 170 and a part of the seed layer are removed, the first and second photoresist layers 140 and 170 may have a plurality of air inlets 191, and the upper electrode 190 may be supported and floated. (FIG. 1J)

Here, the air inlet 191 is formed in the floating upper electrode 190 region, the lower electrode 131 is formed on the membrane spaced apart inside the upper electrode 190.

As shown in FIG. 2, the acoustic sensing device of the present invention manufactured by the above-described process is formed on the surface of the substrate 400 and the upper electrode 310 that is supported and floated on the substrate 400, and the upper electrode ( The lower electrode 320 is spaced apart from the 310 and formed on the surface of the substrate 400.

A plurality of air inlets 311 are formed in the floating region of the upper electrode 310, and the upper electrode 310 is connected to the electrode pad 312.

The lower electrode 320 is also connected to the electrode pad 322.

According to the present invention, the acoustic sensing structure of the condenser microphone is manufactured by performing the manufacturing process as described above, and after inserting and fixing the acoustic sensing element in a metal can or an electromagnetic shielded ceramic or plastic package, a circuit element is added if necessary. The condenser microphone is manufactured by connecting the electrodes and sealing the package except for the part where sound can enter.

In addition, the CMOS, bipolar, and biCMOS processes may be preceded to integrate additional circuits before the manufacturing process of the acoustic sensing device is performed.

The present invention can reduce the manufacturing cost by forming a metal upper electrode by a plating process without forming a thick upper electrode made of polycrystalline silicon and nitride oxide film, as in the prior art, by using a MEMS (Micro Electro Mechanical System) process technology By manufacturing, the effect of realizing an ultra-small device occurs.

Although the invention has been described in detail only with respect to specific examples, it will be apparent to those skilled in the art that various modifications and variations are possible within the spirit of the invention, and such modifications and variations belong to the appended claims.

Claims (2)

A first step of sequentially forming a silicon oxide film and a silicon nitride film on the upper and lower portions of the silicon substrate; Forming a lower electrode of the acoustic sensing device in a portion of the upper portion of the silicon nitride film on the silicon substrate; A third step of forming a first photoresist layer surrounding the silicon nitride layer and the lower electrode, and etching the first photoresist layer to form a plurality of grooves in a portion spaced apart from the lower electrode; A fourth step of forming a seed layer formed of a metal surrounding the first photoresist layer and the plurality of grooves; A second photoresist layer is formed on the seed layer, and a part of the second photoresist layer is removed to form the plurality of groove regions for forming a support part and an electrode pad of the acoustic sensing element, and the lower electrode spaced apart from the plurality of grooves. A fifth step of forming a plurality of small grooves for forming air inlets of the acoustic sensing element thereon; A sixth step of plating a metal layer on the plurality of grooves and the plurality of small grooves; A seventh process of sequentially etching the silicon nitride film, the silicon oxide film, and the silicon substrate under the silicon substrate to remove a portion thereof to form a membrane in which the silicon oxide film and the silicon nitride film under the lower electrode are floated; Steps; And an eighth step of removing the first and second photoresist layers and a part of the seed layer to have a plurality of air inlets, and to form an upper electrode which is supported by a plurality of support parts and floats. The method of claim 1, A substrate manufactured by performing the process from the first step to the eighth step, After cutting each unit device, insert and fix it to any one selected from metal cans, electromagnetic shielded ceramic and plastic packages, and then add additional circuit elements to connect electrodes and enter sound. A method of manufacturing an acoustic sensing element, characterized in that the sealing and packaging.