CN112141996A

CN112141996A - Automatic focusing device and manufacturing method thereof

Info

Publication number: CN112141996A
Application number: CN202010574106.8A
Authority: CN
Inventors: 陈亭蓉; 林诗玮
Original assignee: Taiwan Semiconductor Manufacturing Co TSMC Ltd
Current assignee: Taiwan Semiconductor Manufacturing Co TSMC Ltd
Priority date: 2019-06-28
Filing date: 2020-06-22
Publication date: 2020-12-29

Abstract

According to some embodiments, an auto-focusing apparatus and a method of manufacturing the same are provided. A method of manufacturing an autofocus device includes forming a cantilever member. The cantilever beam member has a ring-like shape. The method also includes forming a piezoelectric member over the cantilever member. The method also includes forming a film on the cantilevered beam member. The membrane has a first region and a second region. The first region has a planar surface and the second region is located between the first region and an inner edge of the cantilevered beam member and has a plurality of corrugations. In addition, the method includes applying a liquid optical medium on the film and sealing the liquid optical medium with a protective layer.

Description

Automatic focusing device and manufacturing method thereof

Technical Field

The present disclosure relates to an auto-focusing apparatus and a method for manufacturing the same.

Background

The semiconductor Integrated Circuit (IC) industry has experienced rapid growth. In the course of IC evolution, functional density (the number of interconnected elements per wafer area) has generally increased, while geometry size (the smallest element (or line) that can be produced using a fabrication process) has decreased. Such scaled-down processes generally provide revenue by increasing production efficiency and reducing associated costs. However, this scaling down is also accompanied by increased complexity in the design and manufacture of devices incorporating these ICs, and to achieve these advances, similar developments in the design of devices are required.

With the advancement of functional density, the development of microelectromechanical systems (MEMS) devices has led to entirely new devices and structures, the dimensions of which are much smaller than previously available. MEMS devices are a technique for forming microstructures having mechanical and electrical properties. A MEMS device may include multiple elements (e.g., movable elements) for performing mechanical functions. Additionally, MEMS devices may include various sensors that sense various mechanical signals, such as pressure, inertial forces, etc., and convert the mechanical signals into their corresponding electrical signals.

MEMS applications include motion sensors, pressure sensors, printer nozzles, and the like. Other MEMS applications include inertial sensors such as accelerometers for measuring linear acceleration and gyroscopes for measuring angular velocity. Also, the MEMS application can be extended to optical applications such as an imaging module, and Radio Frequency (RF) applications such as an RF switch.

Disclosure of Invention

According to an embodiment of the present disclosure, a method for manufacturing an auto-focusing apparatus includes: forming a cantilever beam member having a loop shape; forming a piezoelectric member on the cantilever member; forming a film on the cantilever beam member, wherein the film has a first region and a second region, the first region has a flat surface, the second region is located between the first region and an inner edge of the cantilever beam member, and the second region has a plurality of corrugated structures; and coating a liquid optical medium on the film and sealing the liquid optical medium with a protective layer.

According to an embodiment of the present disclosure, a method for manufacturing an auto-focusing apparatus includes: forming a support layer on a substrate layer, wherein the support layer has a central region and a peripheral region surrounding the central region; forming a dielectric layer on the support layer; forming a piezoelectric member on the dielectric layer opposite to the peripheral region of the support layer; patterning the dielectric layer to form a first protrusion and a second protrusion in the central region of the support layer; covering the dielectric layer with a film conformally formed over the first and second protrusions; coating a liquid optical medium on the film, and sealing the liquid optical medium with a protective layer; and etching the base layer, the support layer and the dielectric layer to expose the film.

According to an embodiment of the present disclosure, an auto-focusing apparatus includes: a cantilever beam component is in a ring shape; a piezoelectric member located above the cantilever member; a membrane having a first region and a second region surrounded by the cantilevered beam member, wherein the first region has a planar surface and the second region is located between the first region and the cantilevered beam member and has a plurality of corrugations; a protective layer over the film; and a liquid optical medium located between the film and the protective layer.

Drawings

Aspects of the present disclosure are best understood from the following [ embodiments ] when read with the accompanying drawings. It should be noted that the various features are not drawn to scale in accordance with standard practice in the industry. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 is a cross-sectional view of an imaging device according to some embodiments of the present disclosure, wherein a film for controlling focus is in a planar state;

FIG. 2 is a cross-sectional view of an imaging device according to some embodiments of the present disclosure, wherein a membrane for controlling focus is in a curved state;

FIG. 3 is a perspective cross-sectional view of a membrane according to some embodiments of the present disclosure;

FIG. 4 is a cross-sectional view of a membrane according to some embodiments of the present disclosure;

FIG. 5 is a bottom view of a cantilever beam and a membrane according to some embodiments of the present disclosure;

FIG. 6 is a flow chart of a method of manufacturing an autofocus device according to some embodiments of the present disclosure;

FIG. 7 is a cross-sectional view of a method of fabricating an autofocus device according to some embodiments of the present disclosure, wherein the piezoelectric member is located on the support layer;

FIG. 8 is a cross-sectional view of a stage in a method of manufacturing an autofocus device according to some embodiments of the present disclosure in which a film, a liquid optical medium, and a protective layer are disposed on a support layer;

fig. 9 is a cross-sectional view of a stage in a method of fabricating an autofocus device according to some embodiments of the present disclosure in which the support layer and base layer are etched to expose the film.

[ notation ] to show

1 imaging module

2: circuit board

3: image sensor

10 automatic focusing device

11: foot member

12 cantilever beam component and cantilever beam layer

13 piezoelectric element

14 film

15: frame

16 liquid optical medium

17 protective layer

31 first convex part

32 second convex part

33 the third convex part

111 outer edge

112 inner edge

116 base layer

117 first dielectric layer

120 hole (C)

121 outer edge

122 inner edge

123 outer part

126 supporting layer

127 second dielectric layer

131 outer edge

136 first metal electrode layer

137 piezoelectric material layer

138 second metal electrode layer

141 center part

142 peripheral portion

143 edge portion

144 flange

160 space (c)

181 trace line

182: trace line

185 passivation layer

21 corrugated structure

22 corrugated structure

23 corrugated structure

213 upper wall

211 first side wall

212 second side wall

311 first side wall

312 second side wall

313, upper surface

O optical axis

L is light

W0, W1, W2, W3, W4, W5, W6, W7, W8 width

H1 height

R1 first region

R2 second region

R3 third region

R4 center region

R5 peripheral region

WR1, WR2, WR3 Width

RD radial

S40 method

S41, S42, S43, S44, S45 operations

Detailed Description

The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. Of course, these specific examples are merely examples and are not intended to be limiting. For example, formation of a first protrusion over or on a second protrusion in the following description may include embodiments in which the first protrusion and the second protrusion are formed in direct contact, and may also include embodiments in which additional features may be formed between the first protrusion and the second protrusion such that the first protrusion and the second protrusion are not in direct contact. Additionally, the present disclosure may repeat element numbers and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Additionally, spatially relative terms, such as "under," "below," "lower," "over," "upper," and the like, may be used herein for ease of description to describe one element or feature's relationship to another (other) element or feature as illustrated in the figures. Spatially relative terms are intended to encompass different orientations of the element in use or operation in addition to the orientation depicted in the figures. The apparatus may be oriented in another direction (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may thus be interpreted as such.

One application of microelectromechanical systems (MEMS) devices is in auto-focusing devices for imaging modules. In this autofocus device, the membrane is positioned over an optical axis of the imaging module. By changing the curvature of the film, the focus of the light incident into the imaging module is adjusted to correctly produce a focused image. However, since wrinkles may be generated on the film due to the uneven distribution of stress, image quality may be degraded in the wrinkled area of the image such as a peripheral edge, etc.

In order to solve the above problems, an embodiment of the present disclosure provides an imaging module having an auto-focusing apparatus, wherein a modified film has a first region and a second region surrounding the first region, wherein the first region has a flat surface, and the second region has a plurality of corrugations. The corrugated structure may be formed in a ring shape and arranged concentrically. By arranging the corrugated structure beside the cantilever beam for supporting the membrane and for changing the curvature of the membrane, the initial stress in the membrane is greatly reduced, thus improving the performance of the image device.

Fig. 1 is a schematic diagram of an imaging module 1 according to some embodiments of the present disclosure. In some embodiments, the imaging module 1 has a circuit board 2, an image sensor 3 and the auto-focusing device 10. Elements of the imaging module 1 may be added or omitted, and the present disclosure should not be limited by the embodiments.

In some embodiments, the image sensor 3 is coupled to an electrical terminal in the circuit board 2, such as a Printed Circuit Board (PCB). The image sensor 3 may be a Charge Coupled Device (CCD) image sensor. A Charge Coupled Device (CCD) image sensor is an electronic device that converts a light pattern or image into a charge pattern or electronic image. A CCD includes several light sensitive elements that have the ability to collect, store and transfer charge from one light sensitive element to another. The photosensitive nature of silicon makes silicon a material of choice in image sensor design. Each light sensitive element represents a picture element or pixel. Using semiconductor technology and design rules, a line or matrix structure forming pixels is fabricated. One or more output amplifiers at the edge of the wafer collect the signal from the CCD. An electronic image can be obtained by transferring pixel-by-pixel charge to the output amplifier line by applying a series of pulses. The output amplifier converts the charge to a voltage. The external electronics convert the output signal into a form suitable for a monitor or frame receiver.

Alternatively, the image sensor 3 may be a Complementary Metal Oxide Semiconductor (CMOS) image sensor. The working voltage of the CMOS image sensor is lower than that of the CCD image sensor, so that the power consumption of the portable application software is reduced. Each CMOS active pixel sensor cell has its own buffer amplifier that can be addressed and read individually. A commonly used cell has four transistors and a light sensitive element. The cell has a transfer gate separating the photosensor from a capacitive "floating diffusion region", a reset gate between the floating diffusion region and a power supply, a source follower transistor for buffering the floating diffusion region from a readout line capacitance, and a row select gate connecting the cell to a readout line. All pixels on a column are connected to a common amplifier. In addition to lower power consumption compared to CCDs, CMOS image sensors are generally simpler in design, typically having a crystal and decoupling.

The autofocus device 10 is located above the image sensor 3 and is configured to change the focus of the light L incident on the image module 1. According to some embodiments of the present disclosure, an autofocus device 10 includes a foot member 11, a cantilever beam member 12, a piezoelectric member 13, a membrane 14, a frame 15, a liquid optical medium 16, and a protective layer 17.

In the following description, unless otherwise stated, the width of any one element presented in the drawings is referred to as the dimension of the element in the direction perpendicular to the optical axis O of the autofocus apparatus 10, and the thickness or height of any one element is referred to as the dimension of the element in the direction parallel to the optical axis O.

The foot member 11 is used to connect the autofocus apparatus 10 to the circuit board 2. In some embodiments, foot member 11 has a ring shape and its center is aligned with optical axis O of imaging module 1. It should be understood, however, that many variations and modifications may be made to the embodiments of the present disclosure. In some embodiments, foot member 11 has a plurality of columns arranged circumferentially about optical axis O of imaging module 1. Foot member 11 may be formed with multiple layers, such as base layer 116 and first dielectric layer 117. The method of forming foot member 11 will be described in detail in the embodiment associated with fig. 6-9.

The cantilever beam member 12 is configured to support the membrane 14. In some embodiments, the cantilevered beam member 12 is located above the foot member 11. The cantilever beam member 12 extends from the outer edge 111 to the inner edge 112 in a direction perpendicular to the optical axis O of the imaging module 1. In some embodiments, the cantilevered beam member 12 has a greater width than the foot member 11 in a direction perpendicular to the optical axis O of the imaging module 1. Specifically, as shown in FIG. 1, the outer edge 121 of the cantilevered beam member 12 is flush with the outer edge 111 of the foot member 11. The inner edge 122 of the cantilever beam member 12 is closer to the optical axis O of the imaging module 1 than the inner edge 112 of the foot member 11. Thus, interference between the foot member 11 and the cantilevered beam member 12 during movement of the cantilevered beam member 12 may be avoided.

In some embodiments, the cantilever member 12 has a ring shape with its center aligned with the optical axis O of the imaging module 1. The aperture 120 is surrounded by an inner edge 122 of the cantilevered beam member 12. The hole 120 allows light incident on the autofocus device 10 to pass therethrough and be projected on the image sensor 3. The cantilever beam member 12 may be formed with multiple layers, such as a support layer 126 and a second dielectric layer 127. The method for forming the cantilevered beam member 12 will be described in detail in the embodiment associated with figures 6-9.

The piezoelectric member 13 is configured to bend the cantilevered beam member 12 to control the curvature of the membrane 14 connected to the cantilevered beam member 12 by applying an electrical charge. In some embodiments, the piezoelectric member 13 is spaced away from the inner edge 122 of the cantilever beam member 12 to allow the cantilever beam member 12 to flex. Specifically, the piezoelectric member 13 overlies an outer portion 123 of the cantilevered beam member 12, the outer portion 123 of the cantilevered beam member 12 is directly connected to an outer edge 121 of the cantilevered beam member 12, and the piezoelectric member 13 overlies an inner portion 124 of the cantilevered beam member 12, the inner portion 124 of the cantilevered beam member 12 is directly connected to an inner edge 122 of the cantilevered beam member 12 that is exposed by the piezoelectric member 13.

In some embodiments, the piezoelectric member 13 includes multiple layers. For example, the piezoelectric member 13 includes a first metal electrode layer 136, a piezoelectric material layer 137, and a second metal electrode layer 138. A first metal electrode layer 136, a layer of piezoelectric material 137, and a second metal electrode layer 138 are sequentially stacked on the cantilever member 12, with the first metal electrode layer 136 in contact with the second dielectric layer 127 of the cantilever member 12. In some embodiments, the piezoelectric material layer 137 comprises a material such as barium titanate or lead zirconate titanate (PZT) ceramic that exhibits a piezoelectric effect when an electric field is applied.

In some embodiments, the two

traces

181 and 182 are electrically connected to the first metal electrode layer 136 and the second metal electrode layer 138, respectively. In operation, an electrical charge is applied to the first and second metal electrode layers 136 and 138 through

traces

181 and 182, and an internal mechanical strain is generated in the piezoelectric material layer 137 in response to an applied electric field generated between the first and second metal electrode layers 136 and 138. Thus, as shown in FIG. 2, the cantilever member 12 in direct contact with the piezoelectric member 13 is curved and the curvature of the diaphragm 14 changes, which causes light L to enter the autofocus device 10 for proper focusing on the image sensor 3.

In some embodiments, the first metal electrode layer 136 constitutes an address electrode to which a variable voltage is applied, and the second metal electrode layer 138 constitutes a ground electrode to which a fixed voltage is applied. It should be understood, however, that many variations and modifications may be made to the embodiments of the present disclosure. The first metal electrode layer 136 and the second metal electrode layer 138 can be connected to two different power sources having different voltages.

In some embodiments, the autofocus device 10 also includes a passivation layer 185 formed over the cantilever member 12 and the piezoelectric member 13. The passivation layer 185 provides passivation to the piezoelectric member 13 and primarily helps to reduce leakage paths from the piezoelectric member 13 to other elements. The passivation layer 185 may include an aluminum oxide, a silicon nitride material, or a silicon oxide material.

Referring to fig. 1, the membrane 14 is configured to control the shape of the liquid optical medium 16 stored in the space 160. For illustrative purposes, the membrane 14 in the embodiment shown in FIG. 1 is divided into a central portion 141, a peripheral portion 142, and an edge portion 143. The central portion 141, the peripheral portion 142, and the edge portion 143 are radially arranged in a direction perpendicular to the optical axis O of the autofocus device 10.

In some embodiments, the membrane 14 extends across the autofocus device 10 and covers the aperture 120 defined by the cantilever beam member 12. That is, as shown in FIG. 1, the central portion 141 is located within the aperture 120 and is surrounded by the inner edge 122 of the cantilevered beam member 12. The peripheral portion 142 surrounds the central portion 141 and covers the inner portion 124 of the cantilever beam member 12 and the piezoelectric member 13. The edge portion 143 surrounds the peripheral portion 142 and covers the outer edge 131 of the piezoelectric member 13. The outer edge 131 of the piezoelectric member 13 may be flush with the outer edge 121 of the cantilever beam member 12. Where the passivation layer 185 is formed over the cantilever beam member 12 and the piezoelectric member 13, the passivation layer 185 underlies the peripheral portion 142 and the edge portion 143 of the membrane 14.

In some embodiments, the membrane 14 also includes a flange 144. The flange 144 surrounds the edge portion 143 for supporting the frame 15, and extends in a direction perpendicular to the optical axis O of the automatic focusing apparatus 10. It should be understood, however, that many variations and modifications may be made to the embodiments of the present disclosure. In some other embodiments, the flange 144 is omitted and the frame 15 is supported by other structures, such as the foot member 11 or the cantilevered beam member 12. The membrane 14 may be made of a material including low stress silicon nitride or silicone and have a thickness in the range of 1um to about 5 um.

The structural features of the central portion 141 of the membrane 14 are described below, according to some embodiments.

Fig. 3 is a perspective cross-sectional view of a central portion 141 of the membrane 14 according to some embodiments of the present disclosure. Fig. 4 is a cross-sectional view of a central portion 141 of a membrane 14 according to some embodiments of the present disclosure. For illustrative purposes, as shown in fig. 3 and 4, the central portion 141 of the membrane 14 is divided into three regions, i.e., a first region R1, a second region R2, and a third region R3. The first region R1, the second region R2, and the third region R3 are continuously arranged in the radial direction RD of the film 14. Note that, in the embodiment shown in fig. 3 and 4, the first region R1, the second region R2, and the third region R3 are integrally formed without forming a gap therebetween.

In some embodiments, the first region R1 has a circular shape and corresponds to the optical axis O of the autofocus device 10. The second region R2 surrounds the first region R1 and has a ring-like shape. The width WR2 of the second region R2 ranges from about 30um to about 300um when viewed from a top view. In some embodiments, the diameter of the first region R1 is in the range of about 1000um to about 2950 um.

The first region R1 has a substantially smooth and flat surface and extends in a first plane P1 in which the support layer 126 abuts the second dielectric layer 127 (fig. 1) in this first plane P1. Second region R2 includes a plurality of corrugations, such as corrugation 21, corrugation 22, and corrugation 23. Each of the corrugated structure 21, the corrugated structure 22, and the corrugated structure 23 forms a ring shape and is arranged concentrically with respect to the optical axis O of the autofocus device 10 (fig. 1).

In some embodiments, each of

corrugations

21, 22 and 23 has a tapered cross-section. For example, the corrugated structure 21 has a first sidewall 211, a second sidewall 212, and an upper wall 213. The first sidewall 211 is connected to the first region R1 and is inclined at an angle B1 (fig. 4) with respect to the first plane P1. The second sidewall 212 is opposite to the first sidewall 211 and is inclined at the same angle B2 with respect to the first plane P1. The upper wall 213 connects top ends of the first and

second sidewalls

211 and 212. The upper wall 213 extends on a second plane P2 parallel to the first plane P1. The bottom of the corrugated structure 21 has a width W1 and the top of the corrugated structure 21 has a width W2. Width W1 is greater than width W2.

In one embodiment, width W2 is in a range from about 1 μm to about 30 μm. The corrugated structure 21 may have the form of a symmetrical trapezoid. That is, angle B1 is equal to angle B2. The angles B1 and B2 may range from about 95 degrees to about 150 degrees. Corrugations 22 and 23 may have a similar or identical configuration to corrugations 21 and will not be described in detail herein.

It should be understood that although in the embodiments shown in fig. 3 and 4, the

corrugated structures

21, 22 and 23 have a trapezoidal shape in their cross-section, the present disclosure is not limited thereto.

Corrugations

21, 22 and 23 may be shaped in any shape, such as rectangular, semi-circular, triangular or combinations thereof.

In some embodiments, a connecting structure is formed between any two

corrugations

21, 22, and 23 that are positioned adjacent to each other. For example, a connecting structure 24 is formed between the corrugated structure 21 and the corrugated structure 22, and a connecting structure 25 is formed between the corrugated structure 22 and the corrugated structure 23. Each of the connection structure 24 and the connection structure 25 has a ring-like shape and is formed concentrically with respect to the optical axis O. The connecting

structures

24 and 25 extend in a first plane P1. In some embodiments, each of the

connection structures

24 and 25 has a width W3 in a range from about 1um to about 30 um. The width W3 may be less than the width W2. In some embodiments, the

connection structures

24 and 25 are omitted.

Corrugations

21, 22 and 23 are immediately adjacent to each other.

In some embodiments, two of

corrugations

21, 22 and 23 located adjacent to each other are spaced apart by the same pitch. For example, corrugations 21 and 22 are spaced apart by a distance W4, and

corrugations

22 and 23 are spaced apart by a distance W5. Distance W4 is equal to distance W5. It should be understood, however, that many variations and modifications may be made to the embodiments of the present disclosure. The spacing between two corrugated structures located adjacent to each other may vary.

In some embodiments, the density and size of the corrugations gradually increase in a radial direction RD of the membrane 14 away from the optical axis O. In other words, in the radial direction RD away from the optical axis O, the pitch of two adjacent corrugated structures gradually increases, and the height or width of the corrugated structure also gradually increases. For example, the corrugated structure 21, the corrugated structure 22, and the corrugated structure 23 are sequentially arranged in a radial direction away from the optical axis O. The distance between the corrugations 22 and the corrugations 23 is greater than the distance between the corrugations 22 and the corrugations 21. Further, the height of the corrugated structure 23 may be greater than the height of the corrugated structure 22, and the height of the corrugated structure 22 may be greater than the height of the corrugated structure 21. In some embodiments, since the initial stress in the film 14 gradually increases in the radial direction RD of the film 14 away from the optical axis O, by arranging the corrugated structure with varying density and size, the initial stress can be appropriately released, and the area ratio of the first region R1 can be simultaneously maximized. Therefore, the imaging quality is greatly improved.

In some embodiments, the sidewalls of the innermost corrugation overlap the boundaries of the first and second regions R1 and R2, and the sidewalls of the outermost corrugation overlap the boundaries of the second and third regions R2 and R3. For example, as shown in fig. 4, the corrugated structure 21 is the innermost corrugated structure (i.e., closest to the optical axis O), and the first sidewall 211 overlaps the boundary of the first region R1 and the second region R2. In addition, the corrugated structure 23 is the outermost corrugated structure (i.e., farthest from the optical axis O), and the side wall 232 thereof overlaps with the boundary of the second region R2 and the third region R3.

The third region R3 surrounds the second region R2. In some embodiments, the third regions R3 have a substantially flat surface extending in the first plane P1 and are free of corrugations. In some embodiments, as shown in fig. 5, the third region R3 is adjacent the inner edge 122 of the cantilevered beam member 12 and is located between the inner edge 122 of the cantilevered beam member 12 and the second region R2. The width WR3 of the third region R3 is greater than 20um and less than 200 um. In some embodiments, the third region R3 is omitted and the second region R2 is adjacent to the inner edge 122 of the cantilevered beam member 12 (i.e., the width WR3 of the third region R3 is equal to 0).

Although fig. 3 and 4 illustrate three corrugations (e.g., corrugation 21, corrugation 22, and corrugation 23) formed in membrane 14, membrane 14 may include any number of corrugations to relieve the initial stress. In some embodiments, the number of corrugations in the membrane 14 is in the range of 1 to 10.

Referring again to fig. 1, the frame 15 is configured to support the protective layer 17. In some embodiments, as shown in fig. 1, the frame 15 is located outside the piezoelectric member 13 (i.e., the side away from the optical axis O of the autofocus device 10), and the frame 15 is located on the flange 144 of the membrane 14. In some embodiments, a portion of the membrane 14 is sandwiched between the frame 15 and the piezoelectric member 13. The frame 15 may be made of a material including SiN and have a width in a range of about 50um to about 100 um. In some embodiments, the frame 15 is located at the outermost edge of the autofocus device 10, and the frame 15 has a ring-type shape and has an outer diameter in the range of about 2000um to about 4500 um.

A protective layer 17 is located over the frame 15. In some embodiments, the space 160 for storing the liquid optical medium is surrounded by the membrane 14, the frame 15 and the protective layer 17. The protective layer 17 is made of a light-transmitting material such as glass. In some embodiments, the thickness of the protective layer 17 is in the range of about 200um to about 300 um. In some embodiments, the protective layer 17 has a thickness of 200 um.

FIG. 6 is a flowchart of a method S40 for manufacturing an autofocus device, according to some embodiments of the present disclosure. While method S40 is illustrated and/or described as a series of acts or events, it will be appreciated that the method is not limited by the illustrated ordering or acts. Thus, in some embodiments, the actions may be performed in a different order than shown, and/or the actions may be performed concurrently. Further, in some embodiments, illustrated acts or events may be subdivided into multiple acts or events, which may be performed at separate times or concurrently with other acts or sub-acts. In some embodiments, some illustrated acts or events may be omitted, and other not illustrated acts or events may be included. It should be understood that other figures are used as examples of the method, but the method is applicable to other structures and/or configurations.

The method S40 includes an operation S41 in which a support layer 126 is formed over the base layer 116. Base layer 116 may be a bulk silicon base, a germanium base, a compound semiconductor base, or other suitable base. In some embodiments, as shown in fig. 7, a first dielectric layer 117 may be formed on the base layer 116 prior to forming the support layer 126. The first dielectric layer 117 may be deposited over the support layer 126 using a suitable deposition technique such as Atomic Layer Deposition (ALD), Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), and the like. The first dielectric layer 117 is then patterned using suitable photolithography and etching techniques to expose a portion of the base layer 116. The removal area of the first dielectric layer 117 may be determined based on the shape and area of the hole 120 shown in fig. 1.

The support layer 126 may be deposited on the exposed support layer 126 and first dielectric layer 117 using a suitable deposition technique such as Atomic Layer Deposition (ALD), Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), and the like. A Chemical Mechanical Polishing (CMP) process may be selectively performed on the deposited support layer 126 such that the resulting support layer 126 may have a substantially planar top surface. In some embodiments, support layer 126 is thicker than first dielectric layer 117. For example, the thickness of the support layer is in the range of about 3um to about 10um, and the thickness of the first dielectric layer 117 is in the range of about 0.1um to about 1 um.

In some embodiments, as shown in fig. 7, the support layer 126 has a central region R4 and a peripheral region R5. The central region R4 has a circular shape that corresponds to the hole 120 that will be formed in a subsequent process. The peripheral region R5 surrounds the central region R4. In some embodiments, the boundary between the central region R4 and the peripheral region R5 overlaps the inner end 118 of the first dielectric layer 117, the inner end 118 defining the width of the hole 120 during a subsequent etching process.

In some embodiments, as shown in fig. 7, after forming the support layer 126, a second dielectric layer 127 is formed on the support layer 126 using a suitable deposition technique such as Atomic Layer Deposition (ALD), Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), or the like, and then an etching process is performed to pattern the second dielectric layer 127 to form the

protrusions

31, 32, and 33. The second dielectric layer 127 may be formed of the same dielectric material as the first dielectric layer 117. The thickness of the second dielectric layer 127 may be in the range of about 1um to about 2 um. In the case where the film 14 is manufactured by molding, the second dielectric layer 127 may be omitted.

The method S40 further includes an operation S42 in which the piezoelectric members 13 are formed on the support layer 126 with respect to the peripheral region R5 of the support layer 12. In some embodiments, to form the piezoelectric member 13, the first metal electrode layer 136, the piezoelectric material layer 137, and the second metal electrode layer 138 are sequentially stacked on the support layer 126 (or the second dielectric layer 127). The first metal electrode layer 136, the piezoelectric material layer 137, and the second metal electrode layer 138 are then patterned using suitable photolithographic techniques to expose the interior 124 of the support layer 126. In some embodiments, the first metal electrode layer 136 and the second metal electrode layer 138 are made of a conductive metal such as platinum, and each has a thickness in a range of about 0.1um to about 0.5 um. The piezoelectric material layer 137 may be made of a material such as barium titanate or lead zirconate titanate (PZT) ceramic, and has a thickness in a range of about 0.3um to about 1 um.

In some embodiments, after forming the layer 137 of piezoelectric material, a passivation layer 185 is deposited on the piezoelectric member 13 and the support layer 126 (or the second dielectric layer 127) using a suitable deposition technique such as Atomic Layer Deposition (ALD), Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), and the like. The layer 137 of piezoelectric material may be patterned to form vias for facilitating electrical connection between the traces 181 and the piezoelectric member 13. The piezoelectric material layer 137 may be made of a material including SiN and have a thickness of about 0.1um to about 0.5 um. The traces 181 may be made of a metal including Ti, Au, or other suitable conductive material and have a thickness of about 0.1um to about 1 um.

Method S40 also includes operation S43, where the film 14 as described in fig. 3 and 4 is prepared. According to some embodiments, as shown in fig. 7, the preparation of the film 14 includes patterning the second dielectric layer 127 to form a plurality of protrusions, such as first protrusions 31, second protrusions 32, and third protrusions 33 on the support layer 126 of the central region R4.

The first, second, and

third protrusions

31, 32, and 33 may be formed to have shapes corresponding to the

corrugations

21, 22, and 23, respectively. In some embodiments, each of the first convex portion 31, the second convex portion 32, and the third convex portion 33 is formed in a ring shape as viewed from the top, and is arranged concentrically. Further, each of the first, second, and

third protrusions

31, 32, 33 tapers away from the support layer 126. For example, as shown in fig. 7, the first convex portion 31 includes a first sidewall 311, a second sidewall 312, and an upper surface 313. The first sidewall 311 is inclined with respect to the support layer 126, and the second sidewall 312 is inclined with respect to the support layer 126. The upper surface 313 connects the first sidewall 311 to the second sidewall 312. The upper surface 313 is parallel to the support layer 126.

In some embodiments, each of the first, second, and

third protrusions

31, 32, 33 has the same width W6, and two adjacent features, such as first protrusion 31 and second protrusion 32, are spaced apart by a distance W7. The distance W7 may be greater than the width W6. In some embodiments, each of first protrusion 31, second protrusion 32, and third protrusion 33 has a height H2 of about 2um to about 15 um. Where the passivation layer 185 is formed over the features 31-33, the height H2 may be slightly less than the height H1 (see fig. 4) of the below-fabricated damascene structure.

In some embodiments, the outermost feature, such as the third protrusion 33, is a predetermined distance W8 from the inner edge 122 of the cantilever beam member 12. In some embodiments, the predetermined distance W8 is greater than 0. For example, the predetermined distance W8 is in the range of about 18um to about 100um (i.e., the difference between the width WR3 and the thickness of the film 14). In some other embodiments, the third protrusion 33 is immediately adjacent the inner edge 122 of the cantilevered beam member 12, and no gap is formed between the bottom edge of the third protrusion 33 and the inner edge 122 of the cantilevered beam member 12.

As shown in fig. 8, the preparation of the membrane 14 further includes forming a polymer layer over the piezoelectric member 13 and the second dielectric layer 127, which polymer layer has been patterned using a suitable deposition technique such as Atomic Layer Deposition (ALD), Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), and the like. The thickness of the polymer layer may range from about 1um to about 5 um. Film 14 may be conformally formed over first protrusion 31, second protrusion 32, and third protrusion 33.

It should be noted that the preparation of the membrane 14 is not limited to the above-described embodiment. In another embodiment, a patterning die (not shown) having a plurality of features corresponding to the corrugations 21 is used for the squeeze film 14. After pressing the film, the patterned mold is removed from the film, and the film retains the inverse shape of the features of the patterned mold. The membrane 14 is then placed over the cantilever beam member 12.

Method S40 also includes operation S44, where the liquid optical medium 16 is applied on the film 14, and the liquid optical medium 16 is sealed by the protective layer 17. In some embodiments, frame 15 is pre-attached to membrane 14 prior to filling with liquid optical medium 16. After filling with the liquid optical medium 16, the protective layer 17 covers the top of the space 160. The protective layer 17 may be attached to the frame 15 by a suitable technique, such as curing, to seal the liquid optical medium 16 in the space 160.

The method S40 also includes an operation S45 in which the base layer 116 and the support layer 126 are etched to expose the membrane 14. In some embodiments, a portion of the base layer 116 and the support layer 126 are removed using one or more etching processes, including, for example, wet etching, dry etching, or a combination of wet etching and dry etching. The resulting structure is shown in fig. 9. Removing a portion of support layer 126 results in aperture 120. In some embodiments, the apertures 120 have a width in the range of about 1500um to about 3000 um. After operation S45, the cantilever beam member 12 and the central portion 141 of the membrane 14 are released. As a result, the curvature of the central portion 141 of the membrane 14 can be adjusted by the strain in the piezoelectric member 13.

Based on the above discussion, it can be seen that the present disclosure has the following advantages. However, it is to be understood that other embodiments may provide additional advantages, and that not all advantages need be disclosed herein, and that no particular advantage is required for all embodiments.

Embodiments of the present disclosure provide an auto-focusing device that uses a membrane having a plurality of corrugated structures to change the focal length of the auto-focusing device. By the corrugated structure, the initial stress in the film is effectively released, and hence the concern of image deterioration caused by wrinkles formed on the film is alleviated. The device performance of an imaging module using an autofocus device is significantly improved because the film has a smoother surface compared to a film without a moire structure.

According to some embodiments, a method of forming an autofocus device is provided. The method includes forming a cantilevered beam member. The cantilever beam member has a ring-like shape. The method also includes forming a piezoelectric member over the cantilever member. The method also includes forming a film on the cantilever beam member. The membrane has a first region and a second region. The first region has a planar surface and the second region is located between the first region and the inner edge of the cantilevered beam member and has a plurality of corrugations. Further, the method includes applying a liquid optical medium on the film and sealing the liquid optical medium with a protective layer. In some embodiments, the films are formed such that the corrugated structures are respectively formed in a ring shape, and the corrugated structures are arranged concentrically with the optical axis of the auto-focusing device. In some embodiments, the membrane is formed such that the corrugations are spaced apart by a distance less than the width of each corrugation. In some embodiments, the step of covering the cantilevered beam member with a film is performed such that a third region of the film surrounding the second region and formed with a planar surface is located between the second region and an inner edge of the cantilevered beam member. In some embodiments, the films are formed such that each corrugated structure is formed with: a first sidewall inclined with respect to a first plane along which the first region extends; a second side wall opposite to the first side wall and inclined with respect to the first plane; the upper surface connects the first sidewall with the second sidewall and is parallel to the first plane. In some embodiments, the membrane is formed such that each corrugation is formed in a cone shape. In some embodiments, the film is formed such that the second region has a width in a range of about 50um to about 300 um. In some embodiments, the piezoelectric member is formed such that a portion of the cantilevered member proximate an inner edge of the cantilevered member does not overlap the piezoelectric member. In some embodiments, the method further includes forming a passivation layer over the piezoelectric member and the cantilever member prior to covering the cantilever member with the film.

According to some embodiments, a method of forming an autofocus device is provided. The method includes forming a support layer on a base layer. The support layer has a central region and a peripheral region surrounding the central region. The method also includes forming a dielectric layer on the support layer. The dielectric layer is patterned to form first and second protrusions in a central region of the support layer. The method also includes forming a piezoelectric member on the dielectric layer relative to a peripheral region of the support layer. Further, the method includes covering the dielectric layer with a film. The film is conformally formed on the first and second convex portions. Further, the method includes applying a liquid optical medium to the film and sealing the liquid optical medium with a protective layer. The method also includes etching the base layer, the support layer, and the dielectric layer to expose the membrane. In some embodiments, the support layer is patterned such that the first convex portion and the second convex portion are each formed in a ring shape and are arranged concentrically. In some embodiments, the patterned support layer is such that the first and second protrusions are spaced apart by a distance greater than a width of each of the first and second protrusions. In some embodiments, the support layer is patterned such that the second protrusions are closer to the peripheral region than the first protrusions, and the second protrusions are spaced apart from a boundary of the central region and the peripheral region of the support layer by a predetermined distance greater than 0. In some embodiments, the support layer is patterned such that the first convex portions comprise: a first sidewall inclined with respect to the support layer; and a first sidewall inclined with respect to the support layer. A second sidewall opposite to the first sidewall and inclined with respect to the support layer; the upper surface connects the first sidewall with the second sidewall and is parallel to the support layer. In some embodiments, the step of patterning the support layer to form the first and second convex portions forms each of the first and second convex portions into a tapered shape. In some embodiments, the step of patterning the support layer to form the first and second protrusions forms each of the first and second protrusions to have a height of about 2um to about 15 um. In some embodiments, the piezoelectric element is formed such that portions of the support layer adjacent to the boundary of the peripheral region and the central region are not overlapped by the piezoelectric element.

According to some embodiments, an autofocus device is provided. The autofocus device includes a loop-type cantilever beam member. The autofocus device also includes a piezoelectric member located on the cantilever member. The autofocus device also includes a membrane having a first region and a second region, the membrane surrounded by the cantilever member. The first region has a planar surface and the second region is located between the first region and the cantilevered beam member and includes a plurality of corrugations. Further, the autofocus device includes a protective layer and a liquid optical medium. A protective layer is over the film, and a liquid optical medium is between the film and the protective layer. In some embodiments, the corrugated structure is formed in a ring shape and is arranged concentrically with the optical axis of the autofocus device. In some embodiments, at least one corrugation has a tapered cross-section. In some embodiments, the membrane further comprises a third region between the cantilever beam member and the second region, the third region having a planar surface. In some embodiments, the second region is proximate to the cantilevered beam member.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure.

Claims

1. A method of manufacturing an auto-focusing device, comprising:

forming a cantilever beam member having a loop shape;

forming a piezoelectric member on the cantilever member;

forming a film on the cantilever beam member, wherein the film has a first region and a second region, the first region has a flat surface, the second region is located between the first region and an inner edge of the cantilever beam member, and the second region has a plurality of corrugated structures; and

coating a liquid optical medium on the film and sealing the liquid optical medium with a protective layer.

2. The method of claim 1, wherein the film is formed such that each of the corrugations is formed in a ring shape, and the plurality of corrugations are arranged concentrically with an optical axis of an auto-focusing device.

3. The method of claim 1, wherein the film is formed such that the plurality of corrugations are spaced apart by a distance that is less than a width of each of the corrugations.

4. The method of claim 1, wherein the membrane covers the cantilevered beam member such that a third region of the membrane surrounds the second region and forms a planar surface, the third region being located between the second region and the inner edge of the cantilevered beam member.

5. The method of claim 1, wherein the film is formed such that each of the corrugations forms:

a first sidewall inclined with respect to a first plane along which the first region extends;

a second side wall located on the opposite side of the first side wall and inclined with respect to the first plane; and

an upper surface connects the first sidewall to the second sidewall and is parallel to the first plane.

6. A method of manufacturing an auto-focusing device, comprising:

forming a support layer on a substrate layer, wherein the support layer has a central region and a peripheral region surrounding the central region;

forming a dielectric layer on the support layer;

forming a piezoelectric member on the dielectric layer opposite to the peripheral region of the support layer;

patterning the dielectric layer to form a first protrusion and a second protrusion in the central region of the support layer;

covering the dielectric layer with a film conformally formed over the first and second protrusions;

coating a liquid optical medium on the film, and sealing the liquid optical medium with a protective layer; and

the base layer, the support layer and the dielectric layer are etched to expose the film.

7. The method of claim 6, wherein the support layer is patterned such that the first protrusions and the second protrusions form a ring shape and are concentrically arranged.

8. The method of claim 6, wherein patterning the support layer such that the first protrusions comprise:

a first side wall is inclined relative to the supporting layer;

a second side wall arranged on the opposite side of the first side wall and inclined relative to the supporting layer; and

an upper surface connects the first sidewall to the second sidewall and is parallel to the support layer.

9. An auto-focusing device, comprising:

a cantilever beam component is in a ring shape;

a piezoelectric member located above the cantilever member;

a membrane having a first region and a second region surrounded by the cantilevered beam member, wherein the first region has a planar surface and the second region is located between the first region and the cantilevered beam member and has a plurality of corrugations;

a protective layer over the film; and

a liquid optical medium is positioned between the film and the protective layer.

10. The autofocus device of claim 9, wherein the corrugated structure is formed in a ring shape and the corrugated structure is arranged concentrically with an optical axis of an autofocus device.