Semiconductor structure and manufacturing method thereof

Abstract

The invention discloses a semiconductor structure and a manufacturing method thereof, and the semiconductor structure comprises a substrate which is provided with a cavity; the diaphragm is suspended above the cavity and anchored to the substrate, and the diaphragm comprises a central area, a peripheral dangling edge area and a coil area located between the central area and the peripheral dangling edge area; the coil is embedded in the coil area of the diaphragm, and the peripheral dangling edge area is provided with a first concave part and a first convex part.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor, in particular to an improved semiconductor structure and a manufacturing method thereof. BACKGROUND

[0002] Micro-Electro-Mechanical Systems (MEMS) is a micro-machining technology that integrates mechanical elements, sensors, actuators, etc. on a microchip. The moving coil MEMS speaker is a moving coil speaker that applies the principle of a traditional moving coil speaker to a miniaturized MEMS chip.

[0003] The working principle of the moving coil MEMS speaker is that when an electric current passes through the coil on the diaphragm, a magnetic field is generated, which interacts with the external magnetic field to generate electromagnetic force, which in turn drives the diaphragm to vibrate and generate sound waves. Sound pressure level (SPL) is a physical quantity that measures the size of sound. For a speaker product, a higher SPL represents a stronger sound output capability, which is one of the important indicators of whether the product can be favored in the market. The diaphragm, as the direct medium for sound generation, its design is crucial to the SPL. SUMMARY

[0004] The main purpose of the present application is to provide an improved semiconductor structure and a manufacturing method thereof to solve the deficiencies or shortcomings of the prior art.

[0005] In one aspect, the present application provides a semiconductor structure, comprising: a substrate having a cavity thereon; a diaphragm suspended above the cavity and anchored to the substrate, wherein the diaphragm comprises a central region, a peripheral suspension region, and a coil region between the central region and the peripheral suspension region; and a coil embedded in the coil region of the diaphragm, wherein the peripheral suspension region has a first recess and a first protrusion.

[0006] According to an embodiment of the present application, the diaphragm comprises a polymer film.

[0007] According to an embodiment of the present application, the polymer film comprises a polyimide (PI) film or a polydimethylsiloxane (PDMS) film.

[0008] According to an embodiment of the present application, the diaphragm comprises a tensile dielectric film.

[0009] According to an embodiment of the present application, the tensile dielectric film comprises a silicon nitride film.

[0010] According to an embodiment of the present application, the first recess and the first protrusion are adjacent, and wherein an inclined side wall is provided between the bottom surface of the first recess and the top surface of the first protrusion.

[0011] According to an embodiment of the present application, the bottom angle formed by the inclined sidewall and the bottom surface of the first recess is obtuse.

[0012] According to an embodiment of the present application, the top angle formed by the inclined sidewall and the top surface of the first protrusion is rounded.

[0013] According to an embodiment of the present application, the thickness of the first protrusion is X and the thickness of the first recess is Y, wherein 0.2≤Y / X≤0.9.

[0014] According to an embodiment of the present application, the central region comprises a second recess.

[0015] Another aspect of the present application provides a method of forming a semiconductor structure, comprising: providing a substrate having a cavity thereon; forming a membrane on the substrate, wherein the membrane is suspended above the cavity and anchored to the substrate, wherein the membrane comprises a central region, a peripheral overhang region, and a coil region between the central region and the peripheral overhang region; and forming a coil in the coil region of the membrane, wherein the peripheral overhang region has a first recess and a first protrusion.

[0016] According to an embodiment of the present application, the membrane comprises a polymer film.

[0017] According to an embodiment of the present application, the polymer film comprises a polyimide (PI) film or a polydimethylsiloxane (PDMS) film.

[0018] According to an embodiment of the present application, the membrane comprises a tensile dielectric film.

[0019] According to an embodiment of the present application, the tensile dielectric film comprises a silicon nitride film.

[0020] According to an embodiment of the present application, the first recess and the first protrusion are adjacent, and wherein an inclined sidewall is disposed between the bottom surface of the first recess and the top surface of the first protrusion.

[0021] According to an embodiment of the present application, the bottom angle formed by the inclined sidewall and the bottom surface of the first recess is obtuse.

[0022] According to an embodiment of the present application, the top angle formed by the inclined sidewall and the top surface of the first protrusion is rounded.

[0023] According to an embodiment of the present application, the thickness of the first protrusion is X and the thickness of the first recess is Y, wherein 0.2≤Y / X≤0.9.

[0024] According to an embodiment of the present application, the central region comprises a second recess.

[0025] The main feature of the present application is to change the diaphragm resonance characteristics by providing a concave-convex structure feature in the peripheral suspension edge area and / or the central area of the diaphragm, thereby achieving the advantageous effect of improving the sound pressure level (SPL) of the MEMS loudspeaker. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a top view schematic diagram of a semiconductor structure of the present application;

[0027] Figure 2 is a cross-sectional view along the cutting line I-I' shown in the top view of the semiconductor structure of the present application. Figure 1

[0028] Figures 3 to 5 is a schematic diagram of a method of forming a semiconductor structure according to an embodiment of the present application.

[0029] SYMBOL DESCRIPTION

[0030] 10 semiconductor structure

[0031] 100 substrate

[0032] 110 diaphragm

[0033] 110a first concave portion

[0034] 110b first convex portion

[0035] 110c second concave portion

[0036] 110d third concave portion

[0037] 110e fourth concave portion

[0038] 110p opening

[0039] 120 coil pattern

[0040] 121 wire pattern

[0041] 202 pad layer

[0042] 210 metal pattern

[0043] 212 dielectric layer

[0044] 220 metal pattern

[0045] 312 dielectric layer

[0046] 312a via

[0047] 320 interconnect structure

[0048] 412 dielectric layer ​

[0049] 412d discontinuity

[0050] a1 bottom corner

[0051] a2 vertex

[0052] CA cavity

[0053] CR central area

[0054] MR coil region

[0055] PR outer edge area

[0056] S1 bottom surface

[0057] S2 Top Surface

[0058] S3 Inclined sidewall

[0059] X, Y thickness Detailed Implementation

[0060] In the following description, details will be illustrated with reference to the accompanying drawings, which also form part of the detailed description of the specification, and are depicted in a manner that describes specific examples in which the embodiments may be practiced. The embodiments described below are described in sufficient detail to enable those skilled in the art to implement them.

[0061] Of course, other embodiments may be adopted, or any structural, logical, and electrical changes may be made without departing from the embodiments described herein. Therefore, the following detailed description should not be regarded as limiting; rather, the embodiments included therein will be defined by the appended claims.

[0062] Please see Figure 1 and Figure 2 ,in, Figure 1 A top view schematic diagram of the semiconductor structure 10 of the present invention is shown. Figure 2 For along Figure 1 The cross-sectional view shown by the tangent line I-I'. The semiconductor structure 10 of the present invention can be used as a component of a MEMS loudspeaker. Those skilled in the art will understand that... Figure 2 Some detailed structures of metals or dielectric layers are not shown.

[0063] like Figure 1 and Figure 2 As shown, the semiconductor structure 10 includes a substrate 100 having a cavity CA. According to embodiments of the invention, the substrate 100 may be, for example, a silicon substrate, but is not limited thereto. The semiconductor structure 10 further includes a diaphragm 110 suspended above the cavity CA, with the periphery of the diaphragm 110 anchored to the upper surface of the substrate 100.

[0064] According to embodiments of the present invention, the diaphragm 110 may comprise, for example, a polymer film. According to embodiments of the present invention, the polymer film may comprise a polyimide (PI) film or a polydimethylsiloxane (PDMS) film. According to another embodiment of the present invention, the diaphragm 110 may comprise a tensile dielectric film. According to embodiments of the present invention, the tensile dielectric film may comprise a silicon nitride film. According to embodiments of the present invention, for example, the diaphragm 110 may be circular, with a diameter, for example, between 3 and 5 mm, but is not limited thereto.

[0065] According to embodiments of the present invention, for example, the diaphragm 110 may include a central region CR, an annular peripheral suspension region PR, and an annular coil region MR located between the central region CR and the peripheral suspension region PR.

[0066] According to an embodiment of the present invention, the semiconductor structure 10 further includes a coil pattern 120 embedded in the coil region MR of the diaphragm 110. According to an embodiment of the present invention, the diaphragm 110 may have a first recess 110a and a first protrusion 110b in the peripheral overhang region PR. According to an embodiment of the present invention, the coil pattern 120 can be connected to an external signal via a wire pattern 121. According to an embodiment of the present invention, the coil pattern 120 and the wire pattern 121 are made of, for example, aluminum or an aluminum alloy, but are not limited thereto.

[0067] like Figure 2 As shown in the enlarged view, the first recess 110a is adjacent to the first protrusion 110b, wherein an inclined sidewall S3 is provided between the bottom surface S1 of the first recess 110a and the top surface S2 of the first protrusion 110b. According to an embodiment of the present invention, for example, the bottom angle a1 formed by the intersection of the inclined sidewall S3 and the bottom surface S1 of the first recess 110a is an obtuse angle. According to an embodiment of the present invention, for example, the apex angle a2 formed by the intersection of the inclined sidewall S3 and the top surface S2 of the first protrusion 110b is a rounded corner.

[0068] According to an embodiment of the present invention, the thickness of the first protrusion 110b is X (that is, the original film thickness), and the thickness of the first recess 110a is Y, wherein 0.2 ≤ Y / X ≤ 0.9. According to an embodiment of the present invention, for example, X can be between 1 and 5 micrometers, preferably between 3 and 4 micrometers, but is not limited thereto.

[0069] It should be understood that, Figure 1 The first recess 110a and the first protrusion 110b in the diaphragm can have various patterns, such as continuous or discontinuous annular, circular, elliptical, etc. According to an embodiment of the present invention, for example, the diaphragm 110 may further include a second recess 110c in the central region CR. For example, the first recess 110a and the second recess 110c can have different patterns, shapes, or areas.

[0070] According to embodiments of the present invention, for example, the diaphragm 110 may further include a third recess 110d and a fourth recess 110e within the peripheral overhang region PR, the first protrusion 110b may be located between the first recess 110a and the third recess 110d, and the fourth recess 110e may be located away from the first recess 110a and the third recess 110d. For example, the first recess 110a, the third recess 110d, and the fourth recess 110e within the peripheral overhang region PR may have different patterns, shapes, or areas. According to embodiments of the present invention, the third recess 110d may overlap with the substrate 100, but is not limited thereto.

[0071] The main feature of this invention is that by providing concave and convex structural features in the peripheral suspension region PR and / or the central region CR of the diaphragm 110, the resonance characteristics of the diaphragm are changed, thereby achieving the beneficial effect of improving the sound pressure level (SPL) of the MEMS loudspeaker.

[0072] Please see Figures 3 to 5 This is a schematic diagram illustrating a method for forming a semiconductor structure according to an embodiment of the present invention, wherein the same layers, regions, or elements are still represented by the same symbols. Figure 3 As shown, a substrate 100 is first provided. According to an embodiment of the present invention, the substrate 100 may be a silicon substrate, but is not limited thereto. According to an embodiment of the present invention, a pad layer 202, such as a silicon oxide layer, may be formed on the substrate 100.

[0073] According to an embodiment of the present invention, a discontinuous metallic pattern 210 may be formed on the padding layer 202, which at least defines a pattern such as Figure 1 The metal pattern 210 includes a central region CR, a peripheral suspension region PR, and a ring-shaped coil region MR, wherein the coil region MR is shielded by a metal pattern 210. According to an embodiment of the invention, a dielectric layer 212, such as a silicon oxide layer, is formed on the metal pattern 210. At discontinuities in the metal pattern 210, the dielectric layer 212 directly contacts the padding layer 202.

[0074] According to an embodiment of the present invention, a metal pattern 220 and a coil pattern 120 may be formed on the dielectric layer 212, wherein the coil pattern 120 is formed within an annular coil region MR and overlaps with the underlying metal pattern 210. According to an embodiment of the present invention, a dielectric layer 312 and an interconnect structure 320 may be further formed on the metal pattern 220 and the coil pattern 120, wherein the interconnect structure 320 is electrically connected to the metal pattern 220 and the coil pattern 120 via a via 312a.

[0075] According to an embodiment of the present invention, a dielectric layer 412 may be further covered on the dielectric layer 312 and the interconnect structure 320. According to an embodiment of the present invention, a discontinuity 412d can be formed in the dielectric layer 412 using photolithography and etching processes, at least exposing the dielectric layer 212 within the central region CR and the peripheral overhang region PR.

[0076] like Figure 4 As shown, a coating or deposition process is then performed to form a film 110 on the dielectric layer 412. According to an embodiment of the present invention, the film 110 may comprise, for example, a polymer film. According to an embodiment of the present invention, the polymer film may comprise a polyimide (PI) film or a polydimethylsiloxane (PDMS) film. According to another embodiment of the present invention, the film 110 may comprise a tensile dielectric film. According to an embodiment of the present invention, the tensile dielectric film may comprise a silicon nitride film.

[0077] According to embodiments of the present invention, recesses 110a, 110c, and 110e can be formed in the film 110 using photolithography and etching processes. Detailed features of the recesses and protrusions of the film 110 (e.g., thickness ratio, bottom angle, top angle, etc.) have been described above and can be found in the reference [reference needed]. Figure 2 Without further details. According to an embodiment of the present invention, an opening 110p can be formed in the film 110 using photolithography and etching processes to expose a portion of the internal interconnect structure 320.

[0078] like Figure 5 As shown, a photolithography and etching process is performed to etch a cavity CA from the back side of the substrate 100. The etching process is, for example, a dry etching process. The self-alignment is aligned with the metal pattern 210. Therefore, after etching the entire thickness of the substrate 100, the pad layer 202 and dielectric layer 312 that are not covered by the metal pattern 210 will continue to be etched until the film 110 is exposed.

[0079] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made in accordance with the claims of the present invention should be included within the scope of the present invention.

Claims

1. A semiconductor structure comprising: A substrate having a cavity; A diaphragm, which is suspended above the cavity and anchored to the substrate, wherein, The diaphragm includes a central region, a peripheral suspension region, and a coil region located between the central region and the peripheral suspension region; as well as A coil is embedded in the coil region of the diaphragm, wherein the peripheral suspension region has a first concave portion and a first convex portion.

2. The semiconductor structure as described in claim 1, wherein, The membrane contains a polymer membrane.

3. The semiconductor structure as described in claim 2, wherein, The polymer membrane comprises a polyimide (PI) membrane or a polydimethylsiloxane (PDMS) membrane.

4. The semiconductor structure as described in claim 1, wherein, The membrane contains a tensile dielectric film.

5. The semiconductor structure as described in claim 4, wherein, The stretched dielectric film contains a silicon nitride film.

6. The semiconductor structure as claimed in claim 1, wherein, The first recess is adjacent to the first protrusion, and an inclined sidewall is provided between the bottom surface of the first recess and the top surface of the first protrusion.

7. The semiconductor structure as claimed in claim 6, wherein, The bottom angle formed by the intersection of the inclined sidewall and the bottom surface of the first recess is an obtuse angle.

8. The semiconductor structure as claimed in claim 6, wherein, The apex angle formed by the intersection of the inclined sidewall and the top surface of the first protrusion is a rounded corner.

9. The semiconductor structure as claimed in claim 1, wherein, The thickness of the first protrusion is X, and the thickness of the first concave part is Y, where 0.2≤Y / X≤0.

9.

10. The semiconductor structure as claimed in claim 1, wherein, The central area contains a second recess.

11. A method for forming a semiconductor structure, comprising: A substrate is provided having a cavity thereon; A film is formed on the substrate, wherein, The diaphragm is suspended above the cavity and anchored to the substrate, wherein the diaphragm includes a central region, a peripheral suspension region, and a coil region located between the central region and the peripheral suspension region; and A coil is formed in the coil region of the diaphragm, wherein the peripheral suspension region has a first concave portion and a first convex portion.

12. The method of claim 11, wherein, The membrane contains a polymer membrane.

13. The method of claim 12, wherein, The polymer membrane comprises a polyimide (PI) membrane or a polydimethylsiloxane (PDMS) membrane.

14. The method of claim 11, wherein, The membrane contains a tensile dielectric film.

15. The method of claim 14, wherein, The stretched dielectric film contains a silicon nitride film.

16. The method of claim 11, wherein, The first recess is adjacent to the first protrusion, and an inclined sidewall is provided between the bottom surface of the first recess and the top surface of the first protrusion.

17. The method of claim 16, wherein, The bottom angle formed by the intersection of the inclined sidewall and the bottom surface of the first recess is an obtuse angle.

18. The method of claim 16, wherein, The apex angle formed by the intersection of the inclined sidewall and the top surface of the first protrusion is a rounded corner.

19. The method of claim 11, wherein, The thickness of the first protrusion is X, and the thickness of the first concave part is Y, where 0.2≤Y / X≤0.

9.

20. The method of claim 11, wherein, The central area contains a second recess.

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