CN101267689A - Microphone chip of capacitance type miniature microphone - Google Patents

Abstract

The invention discloses a microphone chip of a capacitance type microphone, which is formed by sequentially defining a release layer, a first electrode layer, a vibration film layer and a sacrificial layer on a substrate by a semiconductor process and a micro electro mechanical technology, using the evaporation and electroplating method to continuously define the second electrode layer and the strengthening layer, using the sound hole image formed by the second electrode layer and the strengthening layer to etch and hollow the sacrificial layer to form an air gap, and then forming a microphone chip connected with the substrate, then, a separation technique is applied to etch and remove the separation layer to separate the microphone chip from the substrate to obtain the microphone chip, because the method adopts the semiconductor process, the micro-electro-mechanical technology and the microphone chip can be manufactured without the cutting process, therefore, the volume of the microphone chip can be accurately reduced, the yield of the whole manufacturing process is improved, and meanwhile, the substrate can be recycled, so that the material cost is reduced.

Description

Microphone chip for condenser miniature microphone

technical field

The invention relates to a chip, in particular to a microphone chip packaged into a miniature microphone.

Background technique

Generally, miniature microphones can be divided into three types: piezoelectric, piezoresistive, and capacitive. Among them, the capacitive miniature microphone has the advantages of high sensitivity, low noise, low distortion, and low power consumption. , And become the mainstream of the current development of miniature microphones.

However, the microphone chip packaged into a capacitive miniature microphone can be simply divided into a single-chip type that consists of a single substrate through multiple semiconductor manufacturing processes, such as lithography, etching, evaporation (sputtering) plating..., and then cutting (sawing). , and the two-chip type that consists of two separately formed chips and then bonded into one.

No matter the microphone chip packaged in a single-chip or a two-chip condenser microphone, the common disadvantage is that bulk etching must be carried out in the manufacturing process to form the necessary components of the condenser microphone. Diaphragm” and “air gap” and other structures; when the bulk etching process is required, the more parts to be etched, the longer the etching time required, and the less controllable the process , the quality of the finished product will vary greatly, and the process yield cannot be improved; in addition, when the wafer is cut, the structure of the formed microphone chip will be damaged, resulting in a decrease in the overall process yield.

Therefore, improving the current microphone chip packaged into a capacitive miniature microphone is a goal that the industry and the academic circles have been working hard for.

Contents of the invention

The purpose of the present invention is to provide a new microphone chip made by using semiconductor manufacturing process, micro-electro-mechanical technology and transfer technique.

Therefore, the present invention provides a microphone chip of a capacitive miniature microphone, which is packaged in a housing and cooperates with a field effect transistor capable of converting capacitance change into voltage change to form a capacitive miniature microphone.

The microphone chip is molded by semiconductor process and includes a diaphragm and an air gap unit.

The vibrating membrane is spaced from the inner wall surface of the casing to form a vibration space for the vibrating membrane to deform, and the vibrating membrane has a first electrode layer made of conductive material, and a first electrode layer made of insulating material and formed on the The vibrating film layer on the first electrode layer includes a vibrating film area and a seed crystal area surrounding the vibrating film area, and the vibrating film area can produce corresponding deformation due to external acoustic energy.

The air gap unit has a second electrode layer made of conductive material, and a strengthening layer defined and formed on the second electrode layer, and the second electrode layer and the strengthening layer together form a Contrary to the air gap wall extending in the direction of the first electrode layer, and a back plate with a sound hole image, the back plate, the air gap wall and the diaphragm area of the diaphragm layer jointly define a sound hole image for the Air gap for air flow.

The beneficial effect of the present invention is that the microphone chip that can be directly packaged in the shell can be directly formed without cutting by using semiconductor manufacturing process, micro-electromechanical technology and detachment technology, so that the volume of the microphone chip can be precisely reduced, and the yield rate of the overall process can be improved. , At the same time, the substrate can also be recycled to reduce the cost of consumables.

Description of drawings

Fig. 1 is a schematic sectional view illustrating a capacitive miniature microphone packaged with a first preferred embodiment of the microphone chip of the capacitive micromic of the present invention;

Fig. 2 is a schematic cross-sectional view illustrating a first preferred embodiment of the microphone chip of the capacitive miniature microphone of the present invention;

Fig. 3 is a flow chart, illustrates the manufacturing method of the microphone chip of Fig. 2;

Fig. 4 is a schematic sectional view illustrating a capacitive miniature microphone packaged in another form after the microphone chip shown in Fig. 2 is flipped 180°;

Fig. 5 is a schematic sectional view illustrating a second preferred embodiment of the microphone chip of the capacitive miniature microphone of the present invention;

FIG. 6 is a flowchart illustrating a manufacturing method of the microphone chip of FIG. 5 .

Detailed ways

The present invention is described in detail below in conjunction with accompanying drawing and embodiment:

Referring to Fig. 1 and Fig. 2, a first preferred embodiment of the microphone chip of the capacitive micro-microphone of the present invention can cooperate with a shell seat 11 to be packaged into a capacitive micro-microphone 1 as shown in Fig. 1 for sensing the outside world change in sound energy.

The shell seat 1 includes a bottom wall 111, a peripheral wall 112 extending upward from the peripheral edge of the bottom wall 111, a top wall 113 connected to the top edge of the peripheral wall 112 and capable of penetrating sound energy, and a The packaging block 114 on the 111 , the bottom wall 111 , the peripheral wall 112 , and the top wall 113 jointly define a packaging space 115 for the microphone chip 2 to be accommodated.

The microphone chip 2 is manufactured using semiconductor manufacturing process, MEMS technology and detachment technology, and includes a vibrating membrane 21 and an air gap unit 22 connected with the vibrating membrane 21 .

The diaphragm 21 is a so-called "flat diaphragm" in the industry, which is connected to the package block 114 and jointly partitions a vibration space 116 with the bottom wall 111 of the shell base 11. The diaphragm 21 also has a A first electrode layer 211 formed of conductive material and connected to the packaging block 114, and a diaphragm layer 212 formed on the first electrode layer 211 with an insulating material, the diaphragm layer 212 also includes a diaphragm region 213, and A seed crystal region 214 surrounds the vibrating membrane region 213 , and the vibrating membrane region 213 can generate corresponding deformation due to external acoustic energy. The first electrode layer 211 is made of metals such as chromium, gold, tantalum, platinum, aluminum, palladium, tungsten, copper, nickel, or an alloy/composite of a combination of these metals. Here, chromium/ Gold is used as an example; and the diaphragm layer 212 can be made of materials such as polyimide, silicon nitride, silicon oxide, metal, and combinations thereof, and polyimide is used as an example for illustration here.

The air gap unit 22 has a second electrode layer 221, and a strong layer 222 defined and formed on the second electrode layer 221, the second electrode layer 221 and the strong layer 222 together form an The air gap wall 223 extending in the direction of the first electrode layer 211, and a back plate 225 with a sound hole image 224, the back plate 225, the air gap wall 223 and the diaphragm area 213 of the diaphragm layer 212 jointly define a Air gap 226 for air flow with sound hole image 224 . Similarly, the second electrode layer 221 is made of metals such as chromium, gold, tantalum, platinum, aluminum, palladium, tungsten, copper, nickel, or a combination of these metals. Here, chromium/gold is used as the material. For example, the reinforcement layer 222 can be made of materials such as nickel, copper, cobalt, iron, acrylic, polyimide, and combinations thereof. Here, nickel is used as an example for illustration.

When the first and second electrode layers 211, 221 of the above-mentioned microphone chip 2 are written into electric charges to form a capacitor, and after being packaged into the housing 11, the capacitive miniature microphone 1 is formed. When the external sound energy comes from the housing 11 When the top wall 113 of the diaphragm penetrates in, the diaphragm area 213 of the diaphragm 21 is affected by it to generate corresponding deformation in the vibration space 116 and the air gap 226, and a capacitance change occurs while deforming. The field effect transistor (FET, not shown in the figure) that converts the capacitance change into a voltage change can convert the capacitance change into an electronic signal for external transmission and use.

It should be noted here that the above is only an illustration based on the structure of the microphone chip 2 of the present invention and the most basic shell base 11. In fact, those who are familiar with this art know that the package block 114, the surrounding wall 112, the top of the shell base 11 The wall 115, the bottom wall 111, etc. can cooperate with the design of whether it is conductive or not, or directly design the circuit in it, or replace it with a circuit board (PCB), so as to meet the needs of practical applications. In addition, the field effect transistor can also be directly Jointly packaged into the shell base 11, or assembled on the circuit design using the circuit board as the peripheral wall 112, top wall 115 or bottom wall 111, because there are many design methods for this part, and it is not the focus of the present invention location, so I won’t repeat them here.

The above-mentioned microphone chip 2 can be understood more clearly after being described in detail with the manufacturing method shown in FIG. 3 .

Referring to FIG. 3, when manufacturing the microphone chip 2, step 301 is implemented first, using a <100> silicon wafer as the substrate 41, and after cleaning through standard cleaning steps, aluminum with a thickness of about 3 μm is deposited on the substrate 41 by electron beam evaporation as a release layer. 42.

Due to the existence of the release layer 42, after the microphone chip 2 connected to the substrate is subsequently molded, the microphone chip 2 can be separated from the substrate 41 by dissolution with a specific etching solution, so as to directly obtain the complete microphone chip 2. Therefore, the constituent material of the release layer 42 only needs to correspond to the substrate 41 and the microphone chip 2, and when it is eroded with an etching solution, only the release layer 42 will be eroded without damaging the substrate 41 and the microphone chip 2. Therefore, , in addition to aluminum, other materials such as oxides, polymer materials, or a combination of these materials can be used; here, aluminum and the subsequent choice of hydrochloric acid as an etching solution are used as an example for illustration.

Then proceed to step 302, after using yellow light lithography to define a predetermined image on the release layer 42, use a thermal resistance evaporation machine to evaporate chromium/gold (Cr/Au) with a thickness of about 150nm, and then remove (Lift-Off) After the undesired portion is defined, the first electrode layer 211 having a predetermined image is formed.

Then proceed to step 303 , using photolithography again to define the diaphragm layer 212 with a predetermined image on the first electrode layer 211 with a photosensitive material, such as polyimide, to complete the manufacture of the diaphragm 21 .

Then proceed to step 304, using a plasma-assisted chemical vapor deposition system (PECVD) to deposit silicon dioxide with a thickness of about 3 μm on the diaphragm region 213 of the diaphragm layer 212, as a sacrificial layer 43 (sacrificial layer) for subsequent etching and hollowing out. ).

Since the existence of the sacrificial layer 43 is to form the shape of the subsequent completion of the air gap unit 22, the principle of selecting the constituent material of the sacrificial layer 43 is that when the sacrificial layer 43 is removed by etching, the etching solution will not damage the microphone. Other structures can be used. Therefore, in addition to the silicon dioxide used in this example, other materials such as polymer materials and aluminum can be used.

Then proceed to step 305. After using yellow light lithography to define a predetermined shape of the sound hole image 224 on the upper surface of the sacrificial layer 43 opposite to the connecting diaphragm 21, the seed crystal region of the diaphragm layer 212 is formed with a thermal resistance evaporation machine. 214 and the sacrificial layer 43 are vapor-deposited with a thickness of about 150nm of chromium/gold (Cr/Au), and then remove (Lift-Off) the undesired part to define and form the second electrode with the shape of the predetermined sound hole image 224 Layer 221.

Proceed to step 306, using the second electrode layer 221 as a seed layer (seed layer), electroplating sufficiently thick nickel (Ni) to form a strong layer 222, at this time, the second electrode layer 221 and the strong layer 222 correspond to the diaphragm area 213 The shape of the formed sound hole image 224 makes the region of the sacrificial layer 43 corresponding to the shape of the sound hole image 224 exposed in the shape corresponding to the sound hole image 224 .

Then proceed to step 307 , using buffered hydrofluoric acid (BOE) to etch and hollow out the sacrificial layer 43 from the exposed portion of the sacrificial layer 43 corresponding to the sound hole image 224 , and complete the fabrication of the air gap unit 22 on the diaphragm 21 .

Finally, step 308 is performed to etch the release layer 42 with hydrochloric acid (HCl), so that the microphone chip 2 is separated from the substrate 41, and the microphone chip 2 as shown in FIG. 2 can be produced, and the substrate 41 can also be recycled. .

Referring to Fig. 4, in addition, the above-mentioned completed microphone chip 1 can also be turned over 180° and stacked on the packaging block 114 with the air gap unit 22, and packaged to produce another form of capacitive miniature microphone 1'.

Referring to Fig. 5, a second preferred embodiment of the microphone chip of the capacitive miniature microphone of the present invention is similar to the microphone chip 2 of the last example, and the diaphragm 51 of the microphone chip 5 of its different place this example belongs to " wrinkle type Diaphragm” only; since the other structures of the microphone chip are similar, I won’t repeat them here.

Referring to FIG. 6 , the above-mentioned diaphragm 51 is manufactured as a "corrugated diaphragm" microphone chip. Step 601 is first implemented, using a <100> silicon wafer as the substrate 41. A predetermined wrinkle image 44 is first defined on the substrate 41 .

Then proceed to step 602 , using electron beam evaporation to deposit aluminum with a thickness of about 3 μm as the release layer 42 .

Then proceed to step 603, after using yellow light lithography to define a predetermined image on the release layer 42, use a thermal resistance evaporation machine to evaporate chromium/gold (Cr/Au) with a thickness of about 150 nm, and then remove (Lift-Off) After the undesired portion, the first electrode layer 211 with a predetermined image is defined and formed in accordance with the wrinkle image 44 .

Then proceed to step 604 , using photolithography again to define the diaphragm layer 212 with a predetermined image on the first electrode layer 211 with a photosensitive material, such as polyimide, to complete the fabrication of the corrugated diaphragm 51 .

Then proceed to step 605 , using a plasma-assisted chemical vapor deposition (PECVD) system to deposit silicon dioxide with a thickness of about 3 μm on the diaphragm region 213 of the diaphragm layer 212 as the sacrificial layer 43 for subsequent etching and hollowing out.

Then proceed to step 606. After using yellow light lithography to define a predetermined sound hole image 224 on the upper surface of the sacrificial layer 43 opposite to the connecting diaphragm 51, the seed crystal region 214 of the diaphragm layer 212 and the diaphragm layer 212 are formed with a thermal resistance evaporation machine. Chromium/gold (Cr/Au) with a thickness of about 150nm is vapor-deposited on the sacrificial layer 43, and after removing (Lift-Off) the undesired part, a second electrode layer with a predetermined sound hole image 224 is defined and formed 221.

Continue to step 607, use the second electrode layer 221 as a seed layer (seed layer), and electroplate sufficiently thick nickel (Ni) to form a strong layer 222. At this time, the second electrode layer 221 and the strong layer 222 correspond to the diaphragm area 213 The shape of the formed sound hole image 224 makes the region of the sacrificial layer 43 corresponding to the shape of the sound hole image 224 exposed in the shape corresponding to the sound hole image 224 .

Then proceed to step 608 , using BOE to etch down the sacrificial layer 43 from the exposed portion of the sacrificial layer 43 corresponding to the shape of the sound hole image 224 , and complete the fabrication of the air gap unit 22 on the corrugated diaphragm 51 .

Finally, step 609 is performed to remove the release layer 42 by etching with hydrochloric acid (HCl), so that the microphone chip 5 is separated from the substrate 41 to obtain the microphone chip 5 , and the substrate 41 can also be recycled.

It should be further explained here that although the microphone chips 2 and 5 of the present invention are described as being packaged into the housing 11, in fact, these microphone chips 2 and 5 can also be directly applied to the system-in-package-also That is, it is directly packaged on the circuit board (Board) without a shell to induce the effect of sound energy. Since there are many types of packaging applications, no more examples will be given here.

As can be seen from the above description, the microphone chips 2 and 5 of the capacitive micro microphone of the present invention mainly use micro-electromechanical technologies such as semiconductor manufacturing process, evaporation and electroplating to define the sacrificial layer 43 and the microphone chips 2 and 5 on the substrate 41 in sequence. structure, and then apply the detachment technology to etch the detachment layer 42 to separate the microphone chips 2, 5 and the substrate 41, so as to obtain the microphone chips 2, 5 and recycle the substrate 41, which can not only avoid bulk etching and make it difficult to be accurate The shortcomings of control can be avoided, and at the same time, the damage to the micro-component structure of the chip caused by cutting can be avoided, and the quality and process yield of the overall microphone chip can be improved, and the creative purpose of the present invention can indeed be achieved.

Claims (11)

1. A microphone chip of a capacitive miniature microphone, which is packaged in a shell to form a capacitive miniature microphone, and can cooperate with a field effect transistor that can convert capacitance changes into voltage changes to convert the acting sound energy into Electrical signal characterized by: The microphone chip is formed in a semiconductor process and includes: A vibrating film is spaced from the inner wall of the shell to form a vibrating space, has a first electrode layer made of conductive material, and a vibrating film layer made of insulating material and formed on the first electrode layer , the diaphragm layer also includes a diaphragm region, and a seed crystal region surrounding the diaphragm region, the diaphragm region can produce corresponding deformation due to external acoustic energy, and An air gap unit has a second electrode layer made of conductive material, and a strengthening layer defined and formed on the second electrode layer, the second electrode layer and the strengthening layer together form a Contrary to the air gap wall extending in the direction of the first electrode layer, and a back plate with a sound hole image, the back plate, the air gap wall and the diaphragm area of the diaphragm layer jointly define a sound hole image for the Air gap for air flow. 2. The microphone chip of the capacitive miniature microphone as claimed in claim 1, characterized in that: the microphone chip is defined to form a release layer and the first electrode layer and the diaphragm layer in sequence on a substrate, and then A sacrificial layer covering the diaphragm region of the diaphragm layer and exposing the seed crystal region is formed on the diaphragm layer, and then the sacrificial layer and the seed crystal are correspondingly formed on the sacrificial layer and the seed crystal region of the diaphragm layer The aspect of the area defines the second electrode layer and the strengthening layer corresponding to the diaphragm area to form the sound hole image in sequence, and finally the sacrificial layer is etched and removed from the exposed part of the sacrificial layer corresponding to the sound hole image, and It is manufactured after removing the release layer by etching to separate the diaphragm from the substrate. 3. The microphone chip of the capacitive miniature microphone as claimed in claim 2, characterized in that: the first and second electrode layers are respectively selected from the group formed by the following for material definition: chromium, gold, tantalum, platinum , aluminum, palladium, tungsten, copper, nickel, and combinations thereof. 4. the microphone chip of capacitive miniature microphone as claimed in claim 2, it is characterized in that: this vibrating membrane layer is to be selected from the group that following constitutes is that material definition forms: polyimide, silicon nitride, silicon oxide, metals, and combinations thereof. 5. The microphone chip of a capacitive miniature microphone as claimed in claim 2, characterized in that: the strengthening layer is formed on the second electrode layer by electroplating, and is selected from the group formed by the following as a material definition : Nickel, copper, cobalt, iron, and combinations thereof. 6. The microphone chip of a capacitive miniature microphone as claimed in claim 2, wherein the reinforcement layer is defined as a material selected from the group consisting of: acrylic, polyimide, and the like combination. 7. The microphone chip of the capacitive miniature microphone as claimed in claim 2, characterized in that: the release layer is selected from the group formed by the following for material definition: aluminum, oxides, polymer materials, and the like The combination. 8. The microphone chip of the capacitive miniature microphone as claimed in claim 2, characterized in that: the section of the diaphragm region of the diaphragm layer is in a flat plate state. 9. The microphone chip of the capacitive miniature microphone as claimed in claim 2, characterized in that: the section of the diaphragm region of the diaphragm layer is in a concave-convex wrinkled state. 10. The microphone chip of the capacitive miniature microphone as claimed in claim 2, characterized in that: the sacrificial layer is selected from the group formed by the following for material definition: silicon dioxide, aluminum, polymer materials, and the etc. combination. 11. The microphone chip of a capacitive miniature microphone as claimed in claim 2 or 10, wherein the sacrificial layer is made by plasma-assisted chemical vapor deposition.

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