TWI449439B - Micromechanical sensor and its manufacturing method - Google Patents

Description

Audio sensing component and method of manufacturing same

The present invention relates to an audio sensing device and a manufacturing method thereof, and more particularly to an audio sensing device having a metal structure attached to a conductor surface of a complementary metal oxide semiconductor by electroless plating and a method of manufacturing the same.

The structure of the audio sensing component is composed of a back plate and a sensing film which are filled with through holes. When a pressure wave of sound acts on the sensing element, the sensing film moves relative to the back plate, so that the back plate and the sensing The capacitance value between the films changes. Since the sound pressure itself is a small pressure change, the sensing element has a relatively high requirement for process precision and stability.

In the prior art, a micromechanical sensor and method for producing the same, which is proposed by Siemens, is disclosed in U.S. Patent No. 6,375,299. The manufacturing method proposed by Siemens is difficult to control the thickness and surface roughness of the sensing film and the thickness of the structural layer of the backing plate is sufficient to have better structural strength. In addition, a micromechanical sensor and method for its production, which is proposed by Infineon, is disclosed in U.S. Patent No. 6,389,902. Infineon's fabrication method requires first dry etching to etch through-holes, and must be backfilled and planarized with oxide, and then other processes are performed and the back-layer structure layer thickness is sufficient to provide better structural strength.

The invention provides an audio sensing component and a manufacturing method thereof, which can reduce the component noise and enhance the sensing sensitivity by integrating the sensing circuit and the audio sensing component on a single wafer in combination with the complementary metal oxide semiconductor manufacturing technology. .

The invention provides an audio sensing component comprising a substrate, a sensing film, a conductive-insulating composite layer, an etch barrier layer and a plating layer. The substrate has at least one hole, and the sensing film is formed on the substrate and covers the holes such that the holes form a back cavity region. A conductive-insulating composite layer is formed on the sensing film to form a sensing chamber with the sensing film. The conductive-insulating composite layer has at least one conductive layer and an insulating layer, and the surface has a plurality of through holes, wherein the tops of the through holes are on the surface of the conductive-insulating composite layer, and the bottom portion is located on the top of the sensing chamber. An etch barrier layer is formed on the conductive-insulating composite layer and exposes portions of the through holes and the conductive-insulating composite layer. The portion of the conductive-insulating composite layer exposed to the through hole and the portion exposed by the etch stop layer are covered with a plating layer to enhance the back plate structure.

From another point of view, the present invention provides a method of fabricating an audio sensing device comprising a wafer fabricated using a standard process having a substrate. A sensing film is deposited on the substrate, followed by deposition of a conductive-insulating composite layer on the sensing film. Finally, an etch stop layer is deposited on the conductive-insulating composite layer, and portions of the through holes and the conductive-insulating composite layer are exposed. The surface of the conductive-insulating composite layer has a plurality of through holes such that the surface of the last insulating layer in the conductive-insulating composite layer is exposed in the through holes. Then again In the electroless plating method, a portion of the conductive-insulating composite layer exposed to the through hole and a portion exposed by the etch barrier layer are covered with a metal to form a plating layer. Then, an anisotropic etching is performed from the bottom of the substrate by using a plasma, and an etching end point is set as a sensing film to form a back cavity region in the substrate. Finally, the bottommost insulating layer of the conductive-insulating composite layer is etched by the through holes to form a sensing chamber between the conductive-insulating composite layer and the sensing film, and the top of the sensing chamber is located at the through holes. bottom.

The present invention proposes an electroless plating method to add a metal structure to a metal surface of a complementary metal oxide semiconductor (CMOS), so that the strength can be enhanced with an increase in thickness, and the intermediate layer of the complementary metal oxide semiconductor material is further enhanced. The etch selectivity of the dielectric layer and the ruthenium oxide is poor. In the component process of the dielectric layer yttrium oxide as the sacrificial material for the sensing chamber, the electroplated metal has the effect of protecting the complementary metal oxide semiconductor metal layer. The dielectric layer between the two layers of metal of such a complementary metal oxide semiconductor can be completely encapsulated without being eroded by the etchant of the sacrificial material of the sensing chamber. Since the metal-dielectric layer-metal formed sandwich structure has a large aspect ratio, the back plate structure is enhanced while the warpage is also suppressed.

The above and other objects, features and advantages of the present invention will become more <RTIgt;

In view of the above, various embodiments will be described with reference to the accompanying drawings to illustrate the audio sensing component of the present invention and the manufacturing method thereof. Those skilled in the art will be better able to understand the present invention.

1A-1E are schematic diagrams respectively showing a method of fabricating an audio sensing element according to an embodiment of the invention. Referring to FIG. 1A, the method provided in this embodiment can form an audio sensing component, such as a condenser microphone, in a complementary MOS wafer fabricated in a complementary MOS process. In the complementary MOS wafer 110 provided in this embodiment, the substrate 111 is included. A sensing film 112 is disposed on the substrate 111, and the material of the sensing film 112 is, for example, a metal, a polycrystalline germanium, or a single crystal germanium. Further, on the sensing film 112, a conductive-insulating composite layer 113 may be disposed.

In this embodiment, the conductive-insulating composite layer 113 includes a first insulating layer 115 and a first conductive layer 116. The material of the first insulating layer 115 may be an oxide or an oxynitride such as cerium oxide or cerium oxynitride, and the material of the first conductive layer 116 may be a metal or a conductive material such as aluminum, copper or titanium. Or titanium nitride...etc. On the upper surface of the first insulating layer 115, the first conductive layer 116 may be disposed. The surface of the first conductive layer 116 has a plurality of through holes 114 such that a portion of the upper surface of the first insulating layer 115 is exposed in the through holes 114. In addition, an etching stopper layer 117 is formed on the conductive-insulating composite layer 113, and a portion of the through hole 114 and the conductive-insulating composite layer 113 is exposed, in order to avoid the most in the conductive-insulating composite layer 113. The upper first conductive layer 116 is damaged during etching to achieve a protective effect. In the present embodiment, a portion of the upper surface of the first conductive layer 116 is exposed by the etch barrier layer 117. Moreover, in some embodiments, the material of the etch stop layer 117 is tantalum nitride.

Referring to FIG. 1B , the method for manufacturing the audio sensing component provided in this embodiment includes first exposing the exposed portion of the barrier layer 117 on the first conductive layer 116 and exposing it to the through hole 114 by means of electroless plating. The portion in the middle forms a plating layer 121. As can be clearly seen from FIG. 1B, the plating layer 121 may be coated on the surface of the portion where the first conductive layer 116 is exposed by the etch barrier layer 117, and the first conductive layer 116 side is exposed on the wall of the through hole 114. The part of the side. By forming the plating layer 114 on the first conductive layer 116, when the first conductive layer 116 is used as the back plate of the audio sensing element, the strength of the structure can be increased, and the etching barrier layer 117 can be used to protect the first layer. A conductive layer 116 prevents the first conductive layer 116 from being damaged during etching. In some embodiments, the plating layer 121 is made of one of nickel, gold or copper.

Next, as shown in FIG. 1C, this embodiment can perform an anisotropic etching from the bottom of the substrate 111 to form the back cavity region 131. In this embodiment, the substrate 111 may be anisotropically etched using an Inductive Coupled Plasma (ICP) process.

In addition, as shown in FIG. 1D, in the conductive-insulating composite layer 113, isotropic etching may be performed from a portion of the first insulating layer 115 exposed in the through hole 114, so that the first conductive layer 116 is in the audio sensing The area in the element is larger than the first insulating layer 115 to form a sensing chamber 141 between the conductive-insulating composite layer 113 and the sensing film 112. In the present embodiment, the top position of the sensing chamber 141 may be at the bottom of the through hole 114. Thereby, a condenser type sounder can be formed on the complementary MOS wafer 110. Wherein, a capacitive effect is formed between the conductive-insulating composite layer 113 and the sensing film 112. It should, and have a capacitance value C, as shown in Figure 1E. When the audio is received, the sensing film 112 is deformed relative to the conductive-insulating composite layer 113, resulting in a change in the capacitance C between the conductive-insulating composite layer 113 and the sensing film 112. Therefore, the present invention can sense the received audio by the change in the capacitance value C.

2A-2E are schematic diagrams showing process steps of an audio sensing device according to another embodiment of the present invention. FIG. 2A is a complementary MOS wafer 210 completed according to a standard complementary MOS process, similar to that shown in FIG. 1A, wherein the sensing film 211 may be made of metal, polysilicon or single crystal germanium. The maximum difference between the complementary MOS wafers 210 and 110 is that the conductive-insulating composite layer 212 disposed on the sensing film 211 is formed by overlapping the conductive layer and the insulating layer. As shown in FIG. 2A, the first insulating layer 214 is formed. Formed on the sensing film 211, the first conductive layer 213 is formed on the first insulating layer 214, and then the second insulating layer 215, the second conductive layer 216, the third insulating layer 217, the third conductive layer 218, and the etching The barrier layers 219 are sequentially stacked to form a sandwich-like composite structure. The material of each insulating layer may be an oxide or an oxynitride such as cerium oxide or cerium oxynitride, and the material of each conductive layer may be a metal or a conductive material such as aluminum, copper, titanium or titanium nitride. ‥and many more. The etch stop layer 219 may be a nitride such as tantalum nitride.

Referring to FIG. 2B again, in the manufacturing method provided in this embodiment, the through hole 221 on the third insulating layer 217 may be firstly formed by, for example, an Inductive Coupled Plasma Reactive Ion Etcher (ICP-RIE). Initially, the conductive-insulating composite layer 212 is anisotropically etched until the first The upper surface of the edge layer 214 is such that the upper surface of the portion of the first insulating layer 214 is exposed in the through holes 221, and the first conductive layer 213, the second insulating layer 215, and the second conductive layer 216 are exposed on the sidewall of the through hole 221 a third insulating layer 217, a third conductive layer 218, and a portion of the side of the etch stop layer 219, wherein a portion of the upper surface of the third conductive layer 218 is exposed by the etch stop layer 219, so that the area of the etch stop layer 219 is smaller than The areas of the first conductive layer 213, the second insulating layer 215, the second conductive layer 216, the third insulating layer 217, and the third conductive layer 218 other than the other layers may be substantially the same in this embodiment, but are not used The invention is defined.

Referring to FIG. 2C, as in the first embodiment, the embodiment may also utilize an electroless plating method to expose a portion of the upper surface of the third conductive layer 218 exposed by the etch barrier layer 219 and the conductive-insulating composite layer 212. A portion of the hole 221 forms a plating layer 231 to cover the upper surface of the third conductive layer 218 portion, and the first conductive layer 213, the second insulating layer 215, the second conductive layer 216, and the first exposed surface of the through hole 221 The sides of the portions of the three insulating layers 217 and the third conductive layer 218. Thus, by the protection of the plating layer 231 and the etching stopper layer 219, it is possible to prevent the above layers from being eroded by the etching liquid in the subsequent process. In addition, the use of the plating layer 231 in the present embodiment further includes avoiding the first conductive layer 213, the second insulating layer 215, the second conductive layer 216, the third insulating layer 217, and the third in the step of FIG. 2B. At least one of the conductive layers 218 protrudes from the influence of the through holes 221 due to incomplete etching. In some embodiments, the plating layer 231 is made of one of nickel, gold or copper.

Then, this embodiment can be used from the bottom of the base 241 by using, for example, Induced Coupled Plasma (ICP) as shown in FIG. 2D. An anisotropic etch is performed to form the back cavity region 242. Next, as in the first embodiment, the first insulating layer 214 may be isotropically etched from the through hole 221 to form a sensing chamber 251 between the conductive-insulating composite layer 212 and the sensing film 211, as shown in FIG. 2E is shown. Likewise, the top of the sensing chamber 251 may be located at the bottom of the through hole 221. Therefore, the present embodiment can also form a capacitive sound receiver on the complementary MOS wafer 210, the principle of which is as described in the first embodiment, and will not be described herein.

In this embodiment, the conductive layer-insulating layer-conductive layer forms a sandwich structure having a large depth-to-width ratio, and the plating layer 231 is protected, so that the back-plate structure formed by the conductive-insulating composite layer 212 is enhanced while being tilted. The curvature is also effectively improved.

While the present invention has been described in its preferred embodiments, the present invention is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application.

140, 250‧‧‧ audio sensing components

111, 241‧‧‧ base

112, 211‧‧‧ Sense film

131, 242‧‧‧ Back cavity area

116, 213‧‧‧ first conductive layer

115, 214‧‧‧ first insulation layer

215‧‧‧Second insulation

216‧‧‧Second conductive layer

217‧‧‧ third insulation layer

218‧‧‧ Third conductive layer

117, 219‧‧ ‧ etch barrier

141, 251‧‧ ‧ sensing chamber

113, 212‧‧‧ Conductive-insulating composite layer

114, 221‧‧‧through holes

121, 231‧‧‧ plating

110, 210‧‧‧Complementary MOS wafers

1A-1E are schematic diagrams showing process steps of an embodiment of the present invention.

2A-2E are schematic diagrams showing process steps of another embodiment of the present invention.

140‧‧‧Audio sensing components

111‧‧‧ base

112‧‧‧Sensing film

131‧‧‧ Back cavity area

141‧‧‧Sensing chamber

113‧‧‧ Conductive-insulating composite layer

114‧‧‧through holes

115‧‧‧First insulation

116‧‧‧First conductive layer

117‧‧‧ etching barrier

121‧‧‧Electroplating

Claims (17)

An audio sensing component includes at least: a substrate including a hole; a sensing film formed on the substrate and covering the hole to form the cavity to form a back cavity region; and a conductive-insulating composite layer, including At least one conductive layer and an insulating layer, and the conductive-insulating composite layer is formed on the sensing film, and forms a sensing chamber with the sensing film, and the surface of the conductive-insulating composite layer has a plurality of through holes, wherein a top of the through hole is on a surface of the conductive-insulating composite layer, and a bottom of the through hole is at a top of the sensing chamber; an etching barrier layer is formed on the conductive-insulating composite layer And exposing the through hole and a portion of the conductive-insulating composite layer; and a plating layer covering a portion of the conductive-insulating composite layer exposed in the through hole, and the conductive-insulating composite layer is etched from the through hole a portion of the barrier layer exposed, wherein the conductive-insulating composite layer comprises: a first insulating layer formed on the sensing film; a first conductive layer formed on the first insulating layer; and a second insulating layer layer, Formed on the first conductive layer; a second conductive layer formed on the second insulating layer; a third insulating layer formed on the second conductive layer; and a third conductive layer formed on the first conductive layer A portion of the upper surface of the third conductive layer is exposed by the etch stop layer. The audio sensing component of claim 1, wherein an area of the first conductive layer in the audio sensing component is greater than the first insulation a layer, wherein the sensing chamber is formed between the conductive-insulating composite layer and the sensing film, wherein the plating layer is used to cover a portion of the upper surface of the first conductive layer, and also covers the first conductive The side of the layer is exposed to the portion of the through-hole wall. The audio sensing device of claim 2, wherein the plating layer further covers a portion of the upper surface of the third conductive layer, and covers the first conductive layer, the second insulating layer, a portion of the second conductive layer, the third insulating layer and the third conductive layer exposed on the sidewall of the through hole, and a portion of the third conductive layer exposed from the etch barrier. The audio sensing component of claim 1, wherein the sensing film is made of one of a metal, a polycrystalline germanium or a single crystal germanium. The audio sensing component of claim 1, wherein the plating layer is made of one of nickel, gold or copper. The audio sensing component of claim 1, wherein the insulating layer is made of cerium oxide or cerium oxynitride. The audio sensing component of claim 1, wherein the etch barrier layer is made of tantalum nitride. A method for manufacturing an audio sensing device, comprising the steps of: providing a wafer having a substrate, wherein the substrate is provided with a sensing film, and the sensing film is sequentially provided with a conductive-insulating composite layer and An etch barrier layer, wherein the conductive-insulating composite layer has a plurality of through holes on a surface thereof such that a surface of a last insulating layer in the conductive-insulating composite layer is exposed in the through hole, and the etch stop layer exposes the a portion of the through hole and the conductive-insulating composite layer; Forming a plating layer on the conductive-insulating composite layer to cover a portion of the conductive-insulating composite layer exposed to the through hole and covering a portion of the conductive-insulating composite layer exposed from the etch stop layer; Etching the bottom of the substrate, and setting an etching end point to the sensing film to form a back cavity region in the substrate; and etching the bottommost insulating layer of the conductive-insulating composite layer from the through hole to conduct the conductive layer Forming a sensing chamber between the insulating composite layer and the sensing film, and a top of the sensing chamber is located at a bottom of the through holes, wherein the conductive-insulating composite layer comprises: a first insulating layer, forming On the sensing film, the bottommost insulating layer; a first conductive layer formed on the first insulating layer; a second insulating layer formed on the first conductive layer; and a second conductive layer, Formed on the second insulating layer; a third insulating layer formed on the second conductive layer; and a third conductive layer formed on the third insulating layer, and a portion of the surface of the third conductive layer is The etch stop layer is exposed. The manufacturing method of claim 8, wherein the plating layer is used to cover a portion of the side of the first conductive layer exposed on the wall of the through hole. The manufacturing method of claim 9, wherein the plating layer further covers a portion of the third conductive layer exposed to the etch barrier layer, and covers the first conductive layer and the second insulating layer The side edges of the second conductive layer, the third insulating layer and the third conductive layer are exposed on the through-hole wall Part of it. The manufacturing method of claim 8, wherein the plating layer is formed on the conductive-insulating composite layer by electroless plating. The manufacturing method according to claim 8, wherein the plating layer is made of one of nickel, gold or copper. The manufacturing method according to claim 8, wherein the step of forming the back cavity region is performed by an anisotropic etching from the bottom of the substrate. The manufacturing method according to claim 13, wherein the step of forming the back cavity region, wherein the step of performing the anisotropic etching is performed by plasma etching. The manufacturing method of claim 8, wherein the sensing film is made of one of a metal, a polycrystalline germanium or a single crystal germanium. The manufacturing method of claim 8, wherein the step of forming the sensing chamber is performed by isotropic etching on a last insulating layer of the conductive-insulating composite layer. The manufacturing method of claim 8, wherein the etching barrier layer is made of tantalum nitride.