Micro-electromechanical system comb actuator and method for forming a comb structure

Abstract

In some embodiments, the present disclosure relates to a microelectromechanical system (MEMS) comb actuator including a comb structure. The comb structure includes: a support layer having a first material; and a plurality of protrusions extending in a first direction away from a first surface of the support layer. The plurality of protrusions are also made of the first material. The plurality of protrusions are separated along a second direction parallel to the first surface of the support layer. The MEMS comb actuator may also include a dielectric liner structure that continuously and completely covers the first surface of the support layer and the plurality of outer surfaces of the plurality of protrusions. The dielectric liner structure includes a connecting portion that continuously connects the topmost surfaces of at least two of the plurality of protrusions.

Description

Technical Field

[0001] The disclosed embodiments relate to a micro-electromechanical system comb actuator and a method for forming a comb structure. Background Art

[0002] Microelectromechanical system (MEMS) devices are becoming increasingly common in modern devices (e.g., smart speakers, hearing aids, and cameras). Many MEMS devices can be classified as either sensors or actuators. MEMS sensors sense the presence of external conditions (e.g., sound waves, light, magnetic signals) and convert them into electrical signals (e.g., voltage, current) for processing. MEMS actuators use electrical signals (e.g., voltage, current) to generate external conditions (e.g., sound waves, light, magnetic signals). MEMS comb actuators, which use electrostatic principles to generate mechanical motion based on electrical signals, are expected to be candidates for fast and low-power MEMS actuators. Summary of the invention

[0003] According to an embodiment of the present disclosure, a micro-electromechanical system comb actuator includes a comb structure and a dielectric pad structure. The comb structure includes a support layer and a plurality of protrusions. The support layer includes a first material. The plurality of protrusions include the first material and extend away from a first surface of the support layer in a first direction, wherein the plurality of protrusions are separated along a second direction, and the second direction is parallel to the first surface of the support layer. The dielectric pad structure continuously and completely covers the first surface of the support layer and the plurality of outer surfaces of the plurality of protrusions, wherein the dielectric pad structure includes a connecting portion, and the connecting portion continuously connects the plurality of topmost surfaces of at least two of the plurality of protrusions.

[0004] According to an embodiment of the present disclosure, a micro-electromechanical system comb actuator includes a comb structure and a dielectric pad structure. The comb structure includes a support layer, a first protrusion and a second protrusion. The support layer includes a semiconductor material. The first protrusion and the second protrusion include the semiconductor material, extend away from the support layer in a first direction, and are spaced apart from each other in a second direction orthogonal to the first direction. The dielectric pad structure is arranged on the comb structure and includes a first sidewall portion and a second sidewall portion. The first sidewall portion completely covers the first sidewall of the first protrusion. The second sidewall portion completely covers the second sidewall of the first protrusion. The first sidewall portion and the second sidewall portion respectively have a uniform thickness measured in the second direction, and the maximum distance of the dielectric pad structure surrounding the first protrusion and measured in the second direction is between the outer sidewall of the first sidewall portion facing away from the first protrusion and the outer sidewall of the second sidewall portion.

[0005] According to an embodiment of the present disclosure, a method for forming a comb-like structure includes: forming a plurality of groove structures in a substrate extending from the topmost surface of the substrate toward the bottommost surface of the substrate; forming a first dielectric layer above the topmost surface of the substrate, wherein the first dielectric layer covers a plurality of inner surfaces of the plurality of groove structures, and the plurality of inner surfaces of the groove structures are defined by a plurality of inner surfaces of the substrate; forming a semiconductor material above the first dielectric layer; removing a plurality of upper portions of the semiconductor material to form the comb-like structure including a plurality of protrusions within the plurality of groove structures; forming a second dielectric layer above the comb-like structure; performing a planarization process to remove a portion of the first dielectric layer and / or a portion of the second dielectric layer to expose the topmost surface of the substrate; forming a third dielectric layer above the second dielectric layer and / or above the topmost surface of the substrate; patterning the third dielectric layer to remove a plurality of portions of the third dielectric layer from the topmost surface of the substrate; and removing a plurality of portions of the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The various aspects of the present disclosure will be best understood by reading the following detailed description in conjunction with the accompanying drawings. It should be noted that, in accordance with standard practice in the industry, the various features are not drawn to scale. In fact, the size of the various features may be arbitrarily increased or reduced for clarity of discussion.

[0007] Figure 1 Perspective views of some embodiments of a microelectromechanical system (MEMS) comb structure including a plurality of semiconductor protrusions continuously covered by a dielectric liner structure are shown.

[0008] Figure 2 and Figure 3 Shown with Figure 1 The perspective views shown correspond to cross-sectional views of some embodiments.

[0009] Figure 4 Perspective views of some other embodiments of a MEMS comb structure including a plurality of semiconductor protrusions continuously covered by a dielectric liner structure are shown.

[0010] Figure 5 and Figure 6 Shown with Figure 4 The perspective views shown correspond to cross-sectional views of some embodiments.

[0011] FIG. 7A to FIG. 7C Various views of some embodiments showing the position of a first MEMS comb structure and a second MEMS comb structure during operation, wherein the dielectric pad structure of the first MEMS comb structure does not contact the dielectric pad structure of the second MEMS comb structure.

[0012] FIG. 8A to FIG. 8C Various views of some other embodiments showing the position of a first MEMS comb structure and a second MEMS comb structure during operation, wherein the dielectric pad structure of the first MEMS comb structure does not contact the dielectric pad structure of the second MEMS comb structure.

[0013] FIG. 9A to FIG. 20 Various views of some embodiments of a method of forming a MEMS comb structure including a plurality of semiconductor protrusions lined with a dielectric liner structure by a self-aligned process are shown.

[0014] Fig.21 Shown with FIG. 9A to FIG. 20 The method shown in FIG. 1 corresponds to a flowchart of some embodiments. DETAILED DESCRIPTION

[0015] The following disclosure provides many different embodiments or examples for implementing the different features of the provided subject matter. Specific examples of components and arrangements are set forth below to simplify the present disclosure. Of course, these are merely examples and are not intended to be limiting. For example, in the following description, forming a first feature on or on a second feature may include an embodiment in which the first feature and the second feature are formed to be in direct contact, and may also include an embodiment in which an additional feature may be formed between the first feature and the second feature so that the first feature and the second feature may not be in direct contact. In addition, the present disclosure may reuse reference numbers and / or letters in various examples. This repetition is for simplicity and clarity, and does not itself represent the relationship between the various embodiments and / or configurations discussed.

[0016] Additionally, for ease of description, spatially relative terms such as "beneath," "below," "lower," "above," "upper," etc. may be used herein to describe the relationship of one element or feature to another (other) element or feature as shown in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein should be interpreted accordingly.

[0017] A microelectromechanical system (MEMS) comb actuator may be used in devices such as, for example, a gyroscope or an optical image stabilizer system in a cell phone camera. In some embodiments, the MEMS comb actuator includes a first comb structure and a second comb structure that move toward and away from each other according to an electrical signal during operation. The first comb structure may include a first support layer and a plurality of protrusions extending outwardly from the first support layer. In addition, a dielectric liner structure may be arranged above the first comb structure so as to continuously cover a plurality of outer surfaces of the plurality of protrusions and a surface of the first support layer. The dielectric liner structure is substantially thin such that the most adjacent protrusions of the plurality of protrusions are spaced apart from each other by a first distance. The first distance is large enough to enable the protrusions of the second comb structure to fit between the most adjacent protrusions of the protrusions of the first comb structure during operation of the MEMS comb actuator. The dielectric liner structure is also thick enough to electrically isolate each of the plurality of protrusions from each other so that the plurality of protrusions each have their own electrostatic potential during operation.

[0018] To form the comb-like structure, the substrate may be patterned to form a plurality of groove structures, wherein each groove structure is separated by a plurality of protrusions of the substrate. A first dielectric layer may be deposited on the substrate and in the plurality of groove structures. A semiconductor material (e.g., polysilicon) may be formed in each groove structure to form a plurality of protrusions protruding from the support layer, wherein a plurality of protrusions comprising semiconductor material are located in the plurality of groove structures and separated by a plurality of protrusions of the substrate. In some embodiments, portions of the first dielectric layer directly overlying the protrusions of the substrate may be removed, and a second dielectric layer may be formed on the exposed surface of the protrusions of the semiconductor material. Subsequently, the first dielectric layer and / or the second dielectric layer directly overlying the protrusions of the substrate may be selectively removed by a patterning process.

[0019] However, removing the first dielectric layer and / or the second dielectric layer may result in excess dielectric material being present on the protrusions of the semiconductor material and / or may result in a very thin or discontinuous coating of dielectric material on the protrusions of the semiconductor material. If excess dielectric material is present on the protrusions of the semiconductor material, the excess dielectric material may collide with the opposing comb structure during operation of the MEMS comb actuator. In addition, if the coating of dielectric material on the protrusions of the semiconductor material is very thin or discontinuous, the protrusions of the semiconductor material may not be protected during manufacturing steps (e.g., substrate patterning) and / or multiple protrusions of the semiconductor material may not be electrically insulated from each other during operation of the MEMS comb actuator so that each protrusion of the semiconductor material has an independent electrostatic potential.

[0020] Various embodiments of the present disclosure provide a method for forming a comb structure having a dielectric liner structure, wherein the dielectric liner structure continuously covers each protrusion of the comb structure for sufficient electrical protection and structural protection. For example, in some embodiments of the present disclosure, after forming a support layer and a protrusion on a substrate covered by a first dielectric layer, a second dielectric layer is formed on the protrusion before removing a portion of the first dielectric layer. After forming the second dielectric layer, a planarization process (e.g., chemical mechanical planarization (CMP)) is performed to remove a portion of the first dielectric layer and / or a portion of the second dielectric layer overlying the substrate. After the planarization process, the upper surface of the first dielectric layer and the upper surface of the second dielectric layer may be substantially coplanar, or in other words, aligned with each other. Next, a third dielectric layer is formed on the substrate, and since the third dielectric layer is formed on the substantially coplanar first dielectric layer and the second dielectric layer, the third dielectric layer may be substantially planar. In other words, the third dielectric layer can be self-aligned with the substantially coplanar first and second dielectric layers, such that the third dielectric layer is substantially planar. In some embodiments, a patterning process is performed to selectively remove portions of the third dielectric layer overlying the substrate. The substrate can then be released. Because the upper surface of the first dielectric layer is aligned with the upper surface of the second dielectric layer before forming the third dielectric layer, and the third dielectric layer is self-aligned to the first and second dielectric layers, in some embodiments, the patterning process of the third dielectric layer can be more controllable.

[0021] Therefore, by performing a planarization process and by adding an additional dielectric layer (e.g., a third dielectric layer), the resulting dielectric pad structure including the first dielectric layer, the second dielectric layer, and the third dielectric layer has a more uniform and controllable thickness, thereby producing a more reliable MEMS comb actuator to electrically and structurally protect the protrusions of the comb structure during operation.

[0022] Figure 1 A perspective view 100 of some embodiments of a MEMS comb structure is shown, wherein at least two protrusions of the MEMS comb structure have topmost surfaces connected by a dielectric liner structure.

[0023] Figure 1 The MEMS comb structure 101 shown includes a support layer 102 and a plurality of protrusions 104 extending from the support layer 102 in a first direction x. In some embodiments, the support layer 102 and the protrusions 104 include the same first material, and the support layer 102 and the protrusions 104 are covered by a dielectric liner structure 106. Figure 1In the perspective view 100 shown, the protrusions 104 of the MEMS comb structure 101 are not visible, as indicated by the double-line brackets, and it should be understood that the protrusions 104 are located below the dielectric liner structure 106. In some embodiments, the first material of the support layer 102 and the protrusions 104 includes a semiconductor material. For example, in some embodiments, the support layer 102 and the protrusions 104 may include polysilicon. Furthermore, in some embodiments, the dielectric liner structure 106 includes a dielectric material such as, for example, silicon nitride, silicon dioxide, etc. Therefore, the dielectric liner structure 106 includes an insulator to provide electrical isolation between the plurality of protrusions 104 during operation of the MEMS comb structure 101, so that each protrusion 104 can maintain a separate electrostatic potential during operation.

[0024] In some embodiments, the plurality of protrusions 104 include at least a first protrusion 104a, a second protrusion 104b, and a third protrusion 104c. The first protrusion 104a, the second protrusion 104b, and the third protrusion 104c may be spaced apart from each other in a second direction y different from the first direction x. In some embodiments, the first direction x may be perpendicular to the second direction y. In some embodiments, the first protrusion 104a may be spaced apart from the second protrusion 104b by a first distance d1, and the second protrusion 104b may be spaced apart from the third protrusion 104c by the same first distance d1. In other embodiments, the first distance d1 may vary between the plurality of protrusions 104.

[0025] In addition, Figure 1 In some embodiments of the MEMS comb structure 101 shown, at least two protrusions 104 of the plurality of protrusions 104 may have topmost surfaces 104T continuously connected to each other by a connecting portion 106c of a dielectric liner structure 106. For example, in some embodiments, the connecting portion 106c of the dielectric liner structure 106 connects the topmost surface 104T of the first protrusion 104a to the topmost surface 104T of the second protrusion 104b. In some embodiments, the connecting portion 106c of the dielectric liner structure 106 is spaced apart from the third protrusion 104c. A third direction z that is different from the first direction x and different from the second direction y may be orthogonal to the topmost surface 104T of the protrusion 104. In some embodiments, the third direction z is perpendicular to the first direction x and the second direction y. In some embodiments, by connecting the first protrusion 104a and the second protrusion 104b with the connecting portion 106c of the dielectric liner structure 106, the electrostatic force of the first protrusion 104a and the second protrusion 104b is increased, which may be desirable in certain applications. In addition, the topmost surface 104T of the protrusion 104 may not be visible in the perspective view 100, as shown by the double-line arrow, and it should be understood that the topmost surface 104T of the protrusion 104 is located below the dielectric liner structure 106.

[0026] Figure 2 and Figure 3 Show respectively that Figure 1 The cross-sectional view 200 and the cross-sectional view 300 of some embodiments of the MEMS comb structure correspond to the cross-sectional line AA′, wherein the dielectric liner structure completely and continuously covers the plurality of protrusions.

[0027] like Figure 2 As shown in the cross-sectional view 200 of FIG. 2 , the protrusions 104 comprising the first material are visible, and the dielectric liner structure 106 completely and continuously covers the outer surface of each protrusion 104. In addition, the first distance d1 between the plurality of protrusions 104 can be measured in the second direction y and can be measured between the plurality of outer surfaces of the plurality of protrusions 104, as shown in FIG. Figure 2 . In some embodiments, in the cross-sectional view 200, the dielectric liner structure 106 may have a first thickness t1, which is the minimum thickness of the dielectric liner structure 106 surrounding the outer surface of the protrusion 104. The first thickness t1 may be thin enough to enable the comb structure to operate mechanically (e.g., bend or move the protrusion 104 according to an electrical signal) while still providing sufficient electrical isolation between the protrusions 104. For example, in some embodiments, the first thickness t1 is in a range between approximately 0.5 microns and approximately 1 micron. It should be understood that other values ​​of the first thickness t1 are also within the scope of the present disclosure.

[0028] In some embodiments, the dielectric liner structure 106 includes: a top portion 106t arranged on the topmost surface 104T of the third protrusion 104c; a first sidewall portion 106f arranged directly along the first sidewall 104f of the third protrusion 104c; a second sidewall portion 106s arranged directly along the second sidewall 104s of the third protrusion 104c; and a bottom portion 106b arranged below the bottommost surface 104B of the third protrusion 104c. The third direction z may be orthogonal to the bottommost surface 104B and the topmost surface 104T of the third protrusion 104c, and the second direction y may be orthogonal to the first sidewall 104f and the second sidewall 104s of the third protrusion 104c. In addition, the first sidewall 104f, the second sidewall 104s, the topmost surface 104T, and the bottommost surface 104B may be continuously connected to each other. The top portion 106t and the bottom portion 106b of the dielectric liner structure 106 may be coupled to each other through the first sidewall portion 106f and the second sidewall portion 106s of the dielectric liner structure 106. In addition, the first sidewall portion 106f may be separated from the second sidewall portion 106s in the second direction y by the third protrusion 104c, and the top portion 106t may be separated from the bottom portion 106b in the third direction z by the third protrusion 104c. The uppermost surface of the first sidewall portion 106f and the uppermost surface of the second sidewall portion 106s are not located above the topmost surface 104T of the third protrusion 104c, and the lowermost surface of the first sidewall portion 106f and the lowermost surface of the second sidewall portion 106s are not located below the bottommost surface 104B of the third protrusion 104c.

[0029] In some embodiments, the dielectric liner structure 106 is formed by performing a planarization process and by adding an additional dielectric layer during a self-aligned manufacturing process, and the first distance d1 between the third protrusion 104c and the fourth protrusion 104d when measured in the entire third direction z can be substantially constant. In other words, for example, the first distance d1 measured from the top portion 106t can be substantially the same as the first distance d1 measured from the bottom portion 106b, and the first distance d1 measured from the bottom portion 106b can also be substantially the same as the first distance d1 measured from the first sidewall portion 106f. In some embodiments, the substantially constant first distance d1 in the third direction z means that the dielectric liner structure 106 does not include a portion that is too thin or too thick. In addition, the self-aligned manufacturing process for forming the dielectric liner structure 106 ensures that the outer surface of the first sidewall portion 106f is substantially coplanar or aligned with the first outer surface of the top portion 106t and the outer surface of the second sidewall portion 106s is substantially coplanar or aligned with the second outer surface of the top portion 106t. In such an embodiment, the dielectric liner structure 106 more reliably electrically and structurally protects the protrusions 104 of the MEMS comb structure (101) during fabrication and operation.

[0030] Furthermore, in some embodiments, the first sidewall portion 106f and the second sidewall portion 106s of the dielectric liner structure 106 may each have a first thickness t1 measured in the second direction y, and the first thickness t1 measured in the entire third direction z is substantially constant. The third protrusion 104c may be arranged between the second protrusion 104b and the fourth protrusion 104d, and the fourth protrusion 104d may be separated from the connecting portion 106c of the dielectric liner structure 106. Furthermore, in some embodiments, the connecting portion 106c of the dielectric liner structure 106 has a top surface, which is located above the top surface of the top portion 106t of the dielectric liner structure 106. In some embodiments, due to the planarization process of the self-aligned manufacturing process, the top surface of the top portion 106t of the dielectric liner structure 106 is substantially planar. Furthermore, in some embodiments, due to the planarization process of the self-aligned manufacturing process, the top surface of the connecting portion 106c of the dielectric liner structure 106 is also substantially planar. Therefore, during operation, the dielectric liner structure 106 can adequately cover and protect the MEMS comb structure ( Figure 1 The MEMS comb structure 101 is shown with protrusions 104 .

[0031] like Figure 3 As shown in the cross-sectional view 300 of FIG. 1 , in some embodiments, the top portion 106t of the dielectric liner structure 106 may include a topmost surface 302, which is coupled to the outermost wall 308 of the first sidewall portion 106f of the dielectric liner structure 106 and the outermost wall 310 of the second sidewall portion 106s of the dielectric liner structure 106 through the first circular surface 304 of the top portion 106t and the second circular surface 306 of the top portion 106t, respectively. In some embodiments, the connecting portion 106c of the dielectric liner structure 106 does not include a circular surface. In some embodiments, the first circular surface 304 and the second circular surface 306 are concave downward in the cross-sectional view 300 relative to a set of axes defined by the third direction z relative to the second direction y.

[0032] In addition, in some embodiments, the dielectric liner structure 106 may include a second distance d2 measured between the outermost wall 308 of the first sidewall portion 106f and the outermost wall 310 of the second sidewall portion 106s in the second direction y. The second distance d2 may be the maximum distance between the outermost wall 308 of the first sidewall portion 106f and the outermost wall 310 of the second sidewall portion 106s. In addition, in some embodiments, the top portion 106t of the dielectric liner structure 106 may include a third distance d3, which is the maximum distance of the top portion 106t measured in the second direction y. The third distance d3 may be measured between the outermost walls of the top portion 106t and in the second direction y. In some embodiments, the third distance d3 is approximately equal to the second distance d2. In addition, the third protrusion 104c is completely and continuously covered by the dielectric liner structure 106.

[0033] Figure 4 A perspective view 400 is shown of some alternative embodiments of a MEMS comb structure including at least two protrusions coupled to each other by a connecting portion of a dielectric liner structure.

[0034] In some embodiments, the connecting portion 106 c of the dielectric liner structure 106 has a first sidewall surface 402 that is substantially coplanar with other portions of the dielectric liner structure 106 arranged above the first protrusion 104 a and the second protrusion 104 b. The first direction x is orthogonal to the first sidewall surface 402 of the connecting portion 106 c of the dielectric liner structure 106 .

[0035] Figure 5 Shows that Figure 4 The cross-sectional view 500 of some embodiments of a MEMS comb structure corresponds to the cross-sectional line BB′.

[0036] like Figure 5 As shown in the cross-sectional view 500 of FIG. 5 , the protrusions 104 of the MEMS comb structure protrude from the first surface 102f of the support layer 102 in the first direction x. The first direction x may be orthogonal to the first surface 102f of the support layer 102. Therefore, in some embodiments, each of the plurality of protrusions 104 is continuously connected to the support layer 102. In addition, in some embodiments, the first distance d1 may be greater than the second distance d2.

[0037] Figure 6 Shows that Figure 4 The cross-sectional line CC′ shown corresponds to a cross-sectional view 600 of some embodiments of a MEMS comb structure.

[0038] like Figure 6As shown in the cross-sectional view 600 of FIG. 1 , in some embodiments, the connecting portion 106 c of the dielectric liner structure 106 includes a first sidewall surface 402. In some embodiments, the first direction x is orthogonal to the first sidewall surface 402 of the connecting portion 106 c. In some embodiments, the MEMS comb structure ( Figure 4 The dielectric liner structure 106 on the first protrusion 104a of the MEMS comb structure 101 shown in FIG. 1 includes a first sidewall 602, and the dielectric liner structure 106 on the second protrusion 104b of the support layer 102 includes a second sidewall 604. In some embodiments, the first direction x may be orthogonal to the first sidewall 602 of the dielectric liner structure 106 on the first protrusion 104a and the second sidewall 604 of the dielectric liner structure 106 on the second protrusion 104b. In some embodiments, the first sidewall surface 402 of the connecting portion 106c, the first sidewall 602 of the dielectric liner structure 106 on the first protrusion 104a, and the second sidewall 604 of the dielectric liner structure 106 on the second protrusion 104b are substantially coplanar. In other embodiments, Figure 6 In the cross-sectional view 600 , the first sidewall surface 402 of the connecting portion 106 c may be located above or below the first sidewall 602 of the dielectric liner structure 106 on the first protrusion 104 a and the second sidewall 604 of the dielectric liner structure 106 on the second protrusion 104 b .

[0039] FIG. 7A to FIG. 7C Various views (perspective view 700A to cross-sectional view 700C) of some embodiments of a MEMS comb actuator are shown that include first and second comb structures that move away from and toward each other in a first direction.

[0040] like Fig. 7A As shown in perspective view 700A of FIG. 1 , in some embodiments of the MEMS comb actuator, the first comb structure 701 is arranged to face the second comb structure 702 in the first direction x. In such an embodiment, the plurality of protrusions 104 of the first comb structure 701 are configured to fit between the plurality of protrusions 104 of the second comb structure 702. During operation, an electrical signal (e.g., voltage, current) may be applied to the first comb structure 701 and / or the second comb structure 702, and the first comb structure 701 and / or the second comb structure 702 may move in response to an electrostatic force generated by the electrical signal within the first comb structure 701 and the second comb structure 702. In some embodiments, the electrical signal (e.g., voltage, current) is applied to the support layer 102, and thus to the protrusions 104. Therefore, in some embodiments, an electrical signal source and a control circuit may be coupled to the first comb structure 701 and the second comb structure 702.

[0041] Furthermore, in some embodiments, the first comb structure 701 and the second comb structure 702 may be arranged on a supporting substrate 704. In some embodiments, the supporting substrate 704 may include various other semiconductor devices (e.g., transistors), and thus, the supporting substrate 704 may be or may include a bulk complementary metal-oxide-semiconductor (CMOS) substrate. In some embodiments, the first comb structure 701 may be directly fixed to the supporting substrate 704, and the second comb structure 702 may be coupled to the supporting substrate 704 via a spring structure 706. In such embodiments, when an electrical signal is applied to the first comb structure 701 and / or the second comb structure 702, the second comb structure 702 may be moved toward and away from the first comb structure 701 in a first direction x via the spring structure 706. In other embodiments, the first comb structure 701 may also be coupled to the supporting substrate 704 via an additional spring structure, so that the first comb structure 701 and the second comb structure 702 may both move toward and away from each other during operation.

[0042] In some embodiments, the first comb structure 701 includes a dielectric liner structure 106, and the dielectric liner structure 106 includes a connecting portion 106c, thereby presenting Figure 1 and / or Figure 4 In some embodiments, the second comb structure 702 includes a dielectric liner structure 106 that does not include a connecting portion 106c, while in other embodiments (not shown), the second comb structure 702 may also include a connecting portion 106c of the dielectric liner structure 106. Since the dielectric liner structure 106 is formed on the first comb structure 701 and the dielectric liner structure 106 is formed on the second comb structure 702 by a self-aligned manufacturing process including adding an additional dielectric layer and a planarization process, the dielectric liner structure 106 completely covers the protrusions 104 of the first comb structure 701 and the protrusions 104 of the second comb structure 702 to provide electrical protection and structural protection for the protrusions 104 of the first comb structure 701 and the protrusions 104 of the second comb structure 702.

[0043] Figure 7B Shows that Fig. 7A The cross-sectional line CC′ corresponds to a cross-sectional view 700B of some embodiments of a MEMS comb actuator, wherein the first comb structure 701 and the second comb structure 702 are located in a first position.

[0044] Figure 7C Shows that Fig. 7AThe cross-sectional line CC′ corresponds to a cross-sectional view 700C of some embodiments of the MEMS comb actuator, wherein the first comb structure 701 and the second comb structure 702 are located in the second position.

[0045] therefore, Figure 7B and Figure 7C The positions of the first comb structure 701 and the second comb structure 702 during operation are shown, wherein when an electrical signal (e.g., voltage, current) is applied to the first comb structure 701 and / or the second comb structure 702, the first comb structure 701 and the second comb structure 702 move toward and away from each other in a first direction x.

[0046] like Figure 7B and Figure 7C As shown in FIG. 1 , the plurality of protrusions 104 of the first comb-like structure 701 and the plurality of protrusions 104 of the second comb-like structure 702 each have a maximum distance equal to the second distance d2, and the plurality of protrusions 104 of the first comb-like structure 701 and the plurality of protrusions 104 of the second comb-like structure 702 are each spaced apart by a first distance d1. Fig. 7A and Figure 7B When moving between the first position and the second position, the first distance d1 is greater than the second distance d2 to prevent collision between the protrusions 104 of the first comb structure 701 and the protrusions 104 of the second comb structure 702. In some embodiments, the first distance d1 of the first comb structure 701 may be different from the first distance d1 of the second comb structure 702, and the second distance d2 of the first comb structure 701 may be different from the second distance d2 of the second comb structure 702.

[0047] However, the dielectric liner structures 106 of the first comb structure 701 and the second comb structure 702 and the protrusions 104 of the first comb structure 701 and the second comb structure 702 are designed to avoid collision between the first comb structure 701 and the second comb structure 702 during operation of the MEMS comb actuator. Fig.13A and Fig. 13B The method of forming a dielectric liner structure 106 in the first dielectric layer ( Fig. 13B A second dielectric layer ( Fig. 13B The second dielectric layer 1302 shown in FIG. 1 is provided to ensure that the protrusion 104 is completely covered by the dielectric liner structure 106. Fig.14A and Fig. 14BIn the method of forming the dielectric liner structure 106, a planarization process is included to ensure that there is no excess first dielectric layer and / or second dielectric layer on the protrusion 104. After the planarization process, the upper surface of the first dielectric layer is substantially coplanar or aligned with the upper surface of the second dielectric layer. In some embodiments, for example, when forming the dielectric liner structure 106 of the first comb-shaped structure 701, the excess first dielectric layer and / or second dielectric layer ( Fig. 14B The first dielectric layer 1002 and the second dielectric layer 1302 shown in FIG. 1 will cause the dielectric liner structure 106 of the first comb structure 701 to collide with the dielectric liner structure 106 of the second comb structure 702. Fig.14A and Fig. 14B A planarization process is used instead of an etching process, thereby preventing excessive removal of the first dielectric layer and / or the second dielectric layer ( Fig. 14B For example, in some embodiments, when forming the dielectric liner structure 106 of the first comb-shaped structure 701, the first dielectric layer and / or the second dielectric layer ( Fig. 14B If the first dielectric layer 1002 , the second dielectric layer 1302 (as shown) are too thin, the dielectric liner structure 106 of the first comb structure 701 may not provide sufficient electrical isolation between the plurality of protrusions 104 of the first comb structure 701 .

[0048] FIG. 8A to FIG. 8C Various views (perspective view 800A to cross-sectional view 800C) of some other embodiments of MEMS comb actuators are shown that include first and second comb structures that move away from and toward each other in a third direction.

[0049] like Fig. 8A As shown in perspective view 800A of FIG. 1 , in some embodiments, the first comb structure 701 and the second comb structure 702 are configured to move toward and away from each other in a third direction z according to an electrical signal (e.g., voltage, current). In some embodiments, the first mechanical support structure 802 is coupled to the support layer 102 of the first comb structure 701, and the second mechanical support structure 804 is coupled to the support layer 102 of the second comb structure 702. It should be understood that the first mechanical support structure 802 and / or the second mechanical support structure 804 can be or can include Fig. 7A A spring structure similar to the spring structure shown (spring structure 706) and Fig. 7A The support substrate shown (support substrate 704) is similar to a support substrate or some other structure.The first mechanical support structure 802 and / or the second mechanical support structure 804 are configured to enable at least one of the first comb structure 701 or the second comb structure 702 to move along a third direction z during operation of the MEMS comb actuator.

[0050] Figure 8B Shows that Fig. 8A The cross-sectional line AA′ corresponds to a cross-sectional view 800B of some embodiments of the MEMS comb actuator, wherein the first comb structure 701 and the second comb structure 702 are located in a first position.

[0051] Figure 8C Shows that Fig. 8A The cross-sectional line AA′ corresponds to a cross-sectional view 800C of some embodiments of the MEMS comb actuator, wherein the first comb structure 701 and the second comb structure 702 are located in the second position.

[0052] like Figure 8B and Figure 8C As shown in , since the first distance d1 is greater than the second distance d2, the first comb structure 701 and the second comb structure 702 can move between the first position and the second position in the third direction z without the protrusions 104 of the first comb structure 701 colliding with the protrusions 104 of the second comb structure 702. In addition, the dielectric liner structure 106 of the first comb structure 701 and the dielectric liner structure 106 of the second comb structure 702 are formed by performing a planarization process and adding an additional dielectric layer during the self-aligned manufacturing process, and when measured in the entire third direction z, the first distance d1 between the plurality of protrusions 104 of the first comb structure 701 can be substantially constant, and when measured in the entire third direction z, the first distance d1 between the plurality of protrusions 104 of the second comb structure 702 can be substantially constant. Furthermore, the dielectric liner structure 106 of the first comb structure 701 and the dielectric liner structure 106 of the second comb structure 702 are formed by performing a planarization process and adding an additional dielectric layer during the self-aligned manufacturing process, the dielectric liner structure 106 of the first comb structure 701 completely covers the outer surface of the protrusions 104 of the first comb structure 701, and the dielectric liner structure 106 of the second comb structure 702 completely covers the outer surface of the protrusions 104 of the second comb structure 702. Therefore, the self-aligned manufacturing process including the planarization process and the formation of an additional dielectric layer ensures that the dielectric liner structure 106 of the first comb structure 701 and the second comb structure 702 are thick enough to provide sufficient electrical isolation between the protrusions 104, while still thin enough to prevent collision between the first comb structure 701 and the second comb structure 702 during operation.

[0053] FIG. 9A to FIG. 20 Various views (perspectives 900A to 2000) of some embodiments of methods of forming a MEMS comb structure of a MEMS comb actuator using a self-aligned process are shown. FIG. 9A to FIG. 20 It is about the method, but it should be understood that FIG. 9A to FIG. 20The structure disclosed in the method is not limited to this method, but can be used as a structure independent of the method.

[0054] like Fig.9A As shown in perspective view 900A of FIG. 1 , a substrate 902 is provided. In some embodiments, the substrate 902 may include a semiconductor body (eg, silicon, CMOS block, germanium, silicon-on-insulator, etc.). Fig.9A As shown in , a plurality of trench structures 904 are formed in a substrate 902 by, for example, photolithography and removal (e.g., wet etching, dry etching, etc.) processes. A plurality of protrusions 906 of the substrate 902 separate the plurality of trench structures 904 from each other in the second direction y. In some embodiments, the substrate 902 further includes a support portion 908 extending away from the trench structure 904 in the first direction x. In some embodiments, the first direction x is substantially perpendicular to the second direction y.

[0055] Fig. 9B Shown along Fig.9A The cross section line AA' Fig.9A A cross-sectional view 900B of some embodiments of a substrate 902 is shown.

[0056] like Fig. 9B As shown in the cross-sectional view 900B of FIG. 1 , a plurality of trench structures 904 of the substrate 902 extend from the topmost surface 902T of the substrate 902 to the bottommost surface 902B of the substrate 902 in the third direction z. However, in some embodiments, the trench structures 904 do not extend completely through the substrate 902. In some embodiments, the topmost surface 902T of the substrate 902 and the bottommost surface 902B of the substrate 902 may be coplanar with a plane substantially orthogonal to the third direction z, and the third direction z is perpendicular to the second direction y. In addition, in some embodiments, the plurality of trench structures 904 may be spaced apart from each other in the second direction y by a plurality of protrusions 906 of the substrate 902.

[0057] like Fig. 10AAs shown in perspective view 1000A of , a first dielectric layer 1002 may be formed over a substrate 902. For example, in some embodiments, the first dielectric layer 1002 is formed over a plurality of protrusions 906 of the substrate 902 and within a plurality of trench structures 904 of the substrate 902, wherein the plurality of trench structures 904 may be defined by a plurality of inner surfaces of the substrate 902. In some embodiments, the first dielectric layer 1002 includes a dielectric material such as, for example, a nitride (e.g., silicon nitride) or an oxide (e.g., silicon dioxide). In some other embodiments, the first dielectric layer 1002 includes, for example, silicon oxynitride, a carbide (e.g., silicon carbide), a low dielectric constant oxide (e.g., carbon-doped oxide, SiCOH), etc. In some embodiments, the first dielectric layer 1002 may be formed by thermal oxidation and / or a deposition process (e.g., chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma enhanced CVD (PE-CVD), atomic layer deposition (ALD), etc.).

[0058] Fig. 10B Shows that Fig. 10A The cross-sectional line AA' shown corresponds to the cross-sectional view 1000B of some embodiments.

[0059] like Fig. 10B As shown in the cross-sectional view 1000B of FIG. 1 , in some embodiments, the first dielectric layer 1002 may have a first thickness t1 that conformally covers the protrusion 906 and the trench structure 904 of the substrate 902. In some embodiments, the first thickness t1 is in a range between, for example, approximately 0.5 micrometers and approximately 1 micrometer. It should be understood that other values ​​of the first thickness t1 are also within the scope of the present disclosure.

[0060] like Fig.11AAs shown in perspective view 1100A of FIG. 1 , in some embodiments, a semiconductor material 1102 is formed over the first dielectric layer 1002. In some embodiments, for example, the first dielectric layer 1002 comprises silicon dioxide, and the semiconductor material 1102 comprises polysilicon. In such embodiments, the semiconductor material 1102 may be formed by an epitaxial growth process. Thus, in some embodiments, the semiconductor material 1102 may be formed in a chamber for a physical vapor deposition (PVD) or chemical vapor deposition (CVD) process. In some other embodiments, the semiconductor material 1102 may be formed in a low pressure CVD (LPCVD) chamber. It should be understood that other materials and deposition processes for the semiconductor material 1102 are also within the scope of the present disclosure.

[0061] Fig. 11B Shows that Fig.11A The cross-sectional line AA' shown corresponds to a cross-sectional view 1100B of some embodiments.

[0062] like Fig. 11B As shown in the cross-sectional view 1100B of FIG. 1 , the semiconductor material 1102 completely fills the plurality of trench structures 904 of the substrate 902. Furthermore, in some embodiments, the semiconductor material 1102 is formed above the topmost surface 902T of the substrate 902. The semiconductor material 1102 may be separated from the substrate 902 by the first dielectric layer 1002.

[0063] like Fig. 12A As shown in perspective view 1200A of , in some embodiments, a first removal process is performed to remove multiple upper portions of the semiconductor material 1102. In some embodiments, the first removal process can be performed in a third direction z. For example, in some embodiments, the first removal process is or includes vertical etching. In addition, in some embodiments, the first removal process removes multiple portions of the semiconductor material 1102, but does not remove the first dielectric layer 1002. Therefore, in some embodiments, the first dielectric layer 1002 remains substantially unchanged after the first removal process.

[0064] In some embodiments, after the first removal process, a MEMS comb structure 101 is formed and includes a support layer 102 located on a support portion 908 of a substrate 902 and a plurality of protrusions 104 extending away from the support layer 102 in a first direction x. The plurality of protrusions 104 of the MEMS comb structure 101 are spaced apart from each other by the protrusions 906 of the substrate 902. The support layer 102 and the protrusions 104 of the MEMS comb structure 101 include a semiconductor material 1102.

[0065] Fig. 12BShows that Fig. 12A The cross-sectional line AA' shown corresponds to the cross-sectional view 1200B of some embodiments.

[0066] like Fig. 12B As shown in the cross-sectional view 1200B of FIG. 1 , after the first removal process, the topmost surfaces 1102T of the semiconductor material 1102, or in other words, the MEMS comb structures ( Fig. 12A The topmost surfaces 104T of the plurality of protrusions 104 of the MEMS comb structure 101 are shown to be below the topmost surface 902T of the substrate 902. In addition, after the first removal process, portions of the first dielectric layer 1002 are not completely covered by the semiconductor material 1102.

[0067] like Fig.13A As shown in perspective view 1300A of FIG. 1 , in some embodiments, a second dielectric layer 1302 is formed on the semiconductor material 1102 of the MEMS comb structure 101. In some embodiments, the second dielectric layer 1302 is also formed on the first dielectric layer 1002. In some embodiments, the second dielectric layer 1302 includes a dielectric material such as (for example) a nitride (for example, silicon nitride) or an oxide (for example, silicon dioxide). In some other embodiments, the second dielectric layer 1302 includes, for example, silicon oxynitride, a carbide (for example, silicon carbide), a low dielectric constant oxide (for example, a carbon-doped oxide, SiCOH), etc. Therefore, in some embodiments, the second dielectric layer 1302 includes the same dielectric material as the first dielectric layer 1002. In some embodiments, the first dielectric layer 1002 can be formed by thermal oxidation and / or a deposition process (for example, chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma enhanced CVD (PE-CVD), atomic layer deposition (ALD), etc.). Therefore, in some embodiments, the second dielectric layer 1302 is formed using the same steps as the first dielectric layer 1002 .

[0068] Fig. 13B Shows that Fig.13A The cross-sectional line AA' shown corresponds to the cross-sectional view 1300B of some embodiments.

[0069] like Fig. 13B As shown in the cross-sectional view 1300B of FIG. 1 , in some embodiments, the second dielectric layer 1302 is formed on the MEMS comb structure ( Fig.13A The second dielectric layer 1302 may be formed directly on the protrusion 104 of the MEMS comb structure 101 shown in FIG. 1 and on the first dielectric layer 1002. In other embodiments, the second dielectric layer 1302 may be formed directly on the MEMS comb structure ( Fig.13AThe second dielectric layer 1302 is formed on the protrusion 104 of the MEMS comb structure 101 shown in the figure, but not directly on the first dielectric layer 1002. For example, in such an embodiment, the second dielectric layer 1302 can be formed by a thermal oxidation process. However, in some embodiments, after the second dielectric layer 1302 is formed, the MEMS comb structure ( Fig.13A The protrusions 104 of the MEMS comb structure 101 shown may be completely surrounded by the first dielectric layer 1002 and the second dielectric layer 1302. Furthermore, in some embodiments, the first dielectric layer 1002 and the second dielectric layer 1302 include the same material, and therefore, the interface 1304 directly between the first dielectric layer 1002 and the second dielectric layer 1302 may be indistinguishable. In some embodiments, after forming the second dielectric layer 1302, the second dielectric layer 1302 has an upper surface above the topmost surface 902T of the substrate 902.

[0070] like Fig.14A As shown in perspective view 1400A of , a planarization process is performed to remove portions of the first dielectric layer 1002 and / or the second dielectric layer 1302 arranged above the topmost surface 902T of the substrate 902. In some embodiments, the planarization process is or includes a chemical mechanical planarization (CMP) process. It should be understood that other planarization processes are within the scope of the present disclosure. After the planarization process, the second dielectric layer 1302 is substantially planar with the topmost surface 902T of the substrate 902. In some embodiments, for example, due to the CMP process, the second dielectric layer 1302 may include some dishing and / or scratching.

[0071] Fig. 14B Shows that Fig.14A The cross-sectional line AA' shown corresponds to the cross-sectional view 1400B of some embodiments.

[0072] like Fig. 14B As shown in the cross-sectional view 1400B of FIG. 1 , the planarization process removes portions of the second dielectric layer 1302 that are directly arranged above the topmost surface 902T of the substrate 902. In addition, in some embodiments, the planarization process removes portions of the first dielectric layer 1002 that are directly arranged above the topmost surface 902T of the substrate 902. Therefore, after the planarization process, the first dielectric layer 1002 has a plurality of upper surfaces that are substantially coplanar or aligned with the plurality of upper surfaces of the second dielectric layer 1302 and the topmost surface 902T of the substrate 902.

[0073] By using the MEMS comb structure ( Fig.14A A second dielectric layer 1302 is formed on the protrusion 104 of the MEMS comb structure 101 shown in the figure to protect the MEMS comb structure ( Fig.14AThe protrusions 104 of the MEMS comb structure 101 shown in FIG. 1 are not affected by the planarization process used to remove the upper portion of the first dielectric layer 1002. In addition, by performing the planarization process, the first dielectric layer 1002 and the second dielectric layer 1302 have substantially planar upper surfaces, thereby improving control and reliability in subsequent processing steps to improve the MEMS comb structure ( Fig.14A The MEMS comb structure 101 shown in FIG. 1 is formed around the dielectric liner structure 101 to form a substantially uniform final dielectric liner structure. Fig. 13B The formation of the second dielectric layer 1302 is shown Fig. 14B The planarization process shown, FIG. 9A to FIG. 20 The method of forming the dielectric liner structure shown is a self-aligned manufacturing process because Fig. 13B The formation of the second dielectric layer 1302 is shown Fig. 14B The planarization process shown ensures that the final dielectric liner structure is Fig.14A The MEMS comb structure 101 shown is not too thin or too thick on the protrusion 104 to provide electrical isolation and structural protection for the protrusion 104. Fig. 14B In the embodiment, after the planarization process, the first dielectric layer 1002 and the second dielectric layer 1302 do not extend above the topmost surface 902T of the substrate 902, and thus the trench structure ( Fig. 10B The trench structure 904 is shown as self-aligned.

[0074] like Fig.15AAs shown in perspective view 1500A of FIG. 1 , in some embodiments, a third dielectric layer 1502 is formed over the MEMS comb structure 101. In such an embodiment, the third dielectric layer 1502 is formed over the first dielectric layer 1002 and the second dielectric layer 1302. In some embodiments, the third dielectric layer 1502 includes a dielectric material such as, for example, a nitride (e.g., silicon nitride) or an oxide (e.g., silicon dioxide). In some other embodiments, the third dielectric layer 1502 includes, for example, silicon oxynitride, a carbide (e.g., silicon carbide), a low dielectric constant oxide (e.g., carbon-doped oxide, SiCOH), etc. Therefore, in some embodiments, the third dielectric layer 1502 includes the same dielectric material as the first dielectric layer 1002 and the second dielectric layer 1302. In some embodiments, the third dielectric layer 1502 may be formed by thermal oxidation and / or a deposition process (e.g., chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma enhanced CVD (PE-CVD), atomic layer deposition (ALD), etc.). Therefore, in some embodiments, the first dielectric layer 1002, the second dielectric layer 1302, and the third dielectric layer 1502 are formed using the same process. In other embodiments, the first dielectric layer 1002, the second dielectric layer 1302, and / or the third dielectric layer 1502 may be formed by different processes. For example, in some embodiments, the first dielectric layer 1002 and the second dielectric layer 1302 may be formed by a thermal oxidation process, while the third dielectric layer 1502 is formed by a PE-CVD process.

[0075] Fig. 15B Shows that Fig.15A The cross-sectional line AA' shown corresponds to the cross-sectional view 1500B of some embodiments.

[0076] In some embodiments, the third dielectric layer 1502 may cover and / or fill the Fig. 14B The planarization process shown in FIG. 1 may cause all or some of the depressions and / or scratches on the first dielectric layer 1002 and / or the second dielectric layer 1302. Therefore, in some embodiments, Fig. 15B The upper surface of the third dielectric layer 1502 in Fig. 14B After the planarization process in Fig. 15B The upper surfaces of the first dielectric layer 1002 and the second dielectric layer 1302 before the third dielectric layer 1502 is formed have few scratches and / or few recesses.

[0077] like Fig. 15BAs shown in the cross-sectional view 1500B of FIG. 1 , the third dielectric layer 1502 is formed on the topmost surface 902T of the substrate 902. In addition, in some embodiments, the third dielectric layer 1502 is also formed on the first dielectric layer 1002 and the second dielectric layer 1302. In some embodiments, since the first dielectric layer 1002 and the second dielectric layer 1302 are substantially coplanar, after the third dielectric layer 1502 is formed, the third dielectric layer 1502 may be substantially planar. Therefore, in some embodiments, the third dielectric layer 1502 may be self-aligned with the substantially coplanar first dielectric layer 1002 and the second dielectric layer 1302, so that the third dielectric layer 1502 is substantially planar. In other embodiments, the third dielectric layer 1502 may be directly formed on the topmost surface 902T of the substrate 902, but not directly formed on the first dielectric layer 1002 and the second dielectric layer 1302. Furthermore, in some embodiments, since the first dielectric layer 1002, the second dielectric layer 1302, and the third dielectric layer 1502 include the same material, the interface 1504 directly between the third dielectric layer 1502 and the first dielectric layer 1002 and the second dielectric layer 1302 may be indistinguishable. Similarly, the interface 1304 directly between the first dielectric layer 1002 and the second dielectric layer 1302 may be indistinguishable.

[0078] like Fig.16A As shown in perspective view 1600A of , in some embodiments, a mask structure 1602 is arranged directly on a portion of the MEMS comb structure 101. The mask structure 1602 can be formed using a photolithography and removal (eg, etching) process. In some embodiments, the mask structure 1602 includes a photoresist material or a hard mask material.

[0079] Fig. 16B Shows that Fig.16A The cross-sectional line AA' shown corresponds to the cross-sectional view 1600B of some embodiments.

[0080] like Fig. 16B As shown in the cross-sectional view 1600B of FIG. 1 , in some embodiments, the mask structure 1602 is arranged in a MEMS comb structure ( Fig.16A In addition, the mask structure 1602 completely, continuously and directly overlies the MEMS comb structure ( Fig.16A Onto the at least two protrusions 104 among the plurality of protrusions 104 of the MEMS comb structure 101 shown.

[0081] like Fig.17AAs shown in perspective view 1700A of FIG. 1700A , in some embodiments, a second removal process is performed to remove portions of the third dielectric layer 1502 that are not directly under the mask structure 1602. In some embodiments, after the second removal process, portions of the first dielectric layer 1002 and portions of the second dielectric layer 1302 are exposed, or in other words, not covered by the third dielectric layer 1502. In some embodiments, the second removal process is performed in a third direction z. For example, in some embodiments, the second removal process is or includes vertical etching.

[0082] Fig. 17B Shows that Fig.17A The cross-sectional line AA' shown corresponds to the cross-sectional view 1700B of some embodiments.

[0083] like Fig. 17B As shown in cross-sectional view 1700B of , after the second removal process, a portion of the third dielectric layer 1502 remains directly between the mask structure 1602 and the topmost surface 902T of the substrate 902. In some embodiments, the second removal process ends before the first dielectric layer 1002 or the second dielectric layer 1302 is at risk of being removed by the second removal process. However, in some other embodiments, some upper portions of the first dielectric layer 1002 and / or the second dielectric layer 1302 are removed as a result of the second removal process because the first dielectric layer 1002 and the second dielectric layer 1302 include the same material as the third dielectric layer 1502. For example, in such other embodiments, after the second removal process, the first dielectric layer 1002 and / or the second dielectric layer 1302 may include a rounded surface (e.g., Figure 3 Circular surface 304, circular surface 306 shown). However, due to Fig.14A and Fig. 14B During the planarization process in FIG. 1 , the third dielectric layer 1502 is self-aligned to the first dielectric layer 1002 and the second dielectric layer 1302, so that the third dielectric layer 1502 is substantially planar and has a substantially constant thickness. Therefore, the second removal process can be better controlled to remove the desired portion of the third dielectric layer 1502 without significantly removing the first dielectric layer 1002 and / or the second dielectric layer 1302. In other words, since the first dielectric layer 1002, the second dielectric layer 1302, and the third dielectric layer 1502 completely and continuously cover the MEMS comb structure ( Fig.17A The MEMS comb structure 101 shown in FIG. 1 is a protrusion 104, and after the second removal process, at least the first dielectric layer 1002 and the second dielectric layer 1302 still sufficiently cover and protect the MEMS comb structure ( Fig.17A Therefore, the second removal process does not expose the MEMS comb structure ( Fig.17AThe MEMS comb structure 101 is shown with protrusions 104 .

[0084] like Fig.18A As shown in perspective view 1800A, the mask structure is removed ( Fig.17A In some embodiments, the mask structure ( 1602 ) is removed by wet etching or dry etching. Fig.17A In some embodiments, by removing the mask structure ( Fig.17A The mask structure 1602 shown in FIG. 1 ), the MEMS comb structure 101, the first dielectric layer 1002, the second dielectric layer 1302 and the third dielectric layer 1502 remain substantially unchanged.

[0085] Fig.18B Shows that Fig.18A The cross-sectional line AA' shown corresponds to the cross-sectional view 1800B of some embodiments.

[0086] like Fig.18B As shown in the cross-sectional view 1800B of FIG. 1800B , in some embodiments, after removing the mask structure ( Fig. 17B After the mask structure 1602 is formed, the third dielectric layer 1502 is used to form the MEMS comb structure ( Fig.18A At least two protrusions 104 among the plurality of protrusions 104 of the MEMS comb structure 101 shown are connected.

[0087] like Fig.19A As shown in perspective view 1900A of FIG. 1 , in some embodiments, from the first dielectric layer, the second dielectric layer and the third dielectric layer ( Fig.18A The first dielectric layer 1002, the second dielectric layer 1302, and the third dielectric layer 1502 are removed from the substrate ( Fig.18A The substrate 902 shown in FIG. 1 is formed to form a dielectric liner structure 106 arranged on the MEMS comb structure 101. The dielectric liner structure 106 includes a first dielectric layer, a second dielectric layer and a third dielectric layer ( Fig.18A The dielectric liner structure 106 includes a first dielectric layer 1002, a second dielectric layer 1302, and a third dielectric layer 1502, and completely and continuously surrounds the protrusions 104 of the MEMS comb structure 101. In addition, the dielectric liner structure 106 may include a connecting portion 106c, which extends in the first direction x while continuously coupling at least two of the plurality of protrusions 104 of the MEMS comb structure 101 to each other. The connecting portion 106c of the dielectric liner structure 106 includes a third dielectric layer ( Fig.18A In some other embodiments, the connecting portion 106c is not required and, therefore, may be omitted. Fig.16A and Fig. 16B The formation mask structure in Fig.16A The step of mask structure 1602 shown.

[0088] In some embodiments, the substrate is removed by an etching process ( Fig.18A In this embodiment, the etching process may be wet etching or dry etching. For example, in some embodiments, the substrate ( Fig.18A In other embodiments, the substrate 902 may be partially removed by vertical etching in the third direction z. Fig.18A In some other embodiments, the substrate can be completely removed by wet etching ( Fig.18A However, the substrate ( Fig.18A The substrate 902 shown in FIG. 1 is released and is no longer arranged between the protrusions 104 of the MEMS comb structure 101. Fig.18A During the period of substrate 902 shown in the figure, the MEMS comb structure 101 and the dielectric liner structure 106 remain substantially unchanged.

[0089] Fig.19B Shows that Fig.19A The cross-sectional line AA' shown corresponds to the cross-sectional view 1900B of some embodiments.

[0090] like Fig.19B As shown in the cross-sectional view 1900B of FIG. 1 , the dielectric liner structure 106 completely and continuously covers the MEMS comb structure ( Fig.19A The outer surface of the protrusion 104 of the MEMS comb structure 101 shown in FIG. 1 is a perspective view of the MEMS comb structure 101. In addition, the connecting portion 106c of the dielectric liner structure 106 continuously connects the MEMS comb structure ( Fig.19A The upper surface of at least two protrusions 104 among the plurality of protrusions 104 of the MEMS comb structure 101 shown.

[0091] like Fig. 20As shown in perspective view 2000 of , in some embodiments, the MEMS comb structure 101 may be arranged on and / or fixed to the supporting substrate 704, and may face the additional MEMS comb structure 2002, thereby forming a MEMS comb actuator. In some embodiments, the additional MEMS comb structure 2002 includes a structure that is the same as or similar to the MEMS comb structure 101. In some embodiments, the spring structure 706 couples the additional MEMS comb structure 2002 to the supporting substrate 704. In addition, in some embodiments (not shown), the MEMS comb structure 101 may also be coupled to the supporting substrate 704 via the spring structure. In addition, in some embodiments, an electrical signal source and a control circuit may be coupled to each of the MEMS comb structure 101 and the additional MEMS comb structure 2002. Therefore, according to the electrical signal, the MEMS comb structure 101 and the additional MEMS comb structure 2002 may move toward or away from each other in the first direction x in response to the electrostatic force between the protrusions 104 of the MEMS comb structure 101 and the protrusions 104 of the additional MEMS comb structure 2002. It should be understood that Fig. 20 Other structures / designs of the features of the MEMS comb actuator shown in FIG. 7 (eg, support substrate 704 , additional MEMS comb structures 2002 , spring structures 706 , etc.) are also within the scope of the present disclosure.

[0092] The plurality of protrusions 104 of the additional MEMS comb structure 2002 are configured to fit between the plurality of protrusions 104 of the MEMS comb structure 101. Due to the self-aligned process used to form the dielectric liner structure 106 of the MEMS comb structure 101 and, in some embodiments, the additional MEMS comb structure 2002, collisions between the protrusions 104 of the additional MEMS comb structure 2002 and the protrusions 104 of the MEMS comb structure 101 are prevented. Furthermore, due to the self-alignment process, the protrusions 104 of the additional MEMS comb structure 2002 and the protrusions 104 of the MEMS comb structure 101 are completely covered by the dielectric pad structure 106 of the additional MEMS comb structure 2002 and the dielectric pad structure 106 of the MEMS comb structure 101, and thus, a gap between the protrusions 104 of the additional MEMS comb structure 2002 and the protrusions 104 of the MEMS comb structure 101 is prevented. FIG. 9A to FIG. 19B The resulting MEMS comb actuator including the MEMS comb structure 101 having the dielectric liner structure 106 formed by a self-aligned process as described in more detail is more reliable.

[0093] Fig.21 A flow chart illustrating some embodiments of a method 2100 of forming a comb structure of a MEMS comb actuator.

[0094] Although method 2100 is shown and described as a series of actions or events below, it should be understood that the order shown of such actions or events should not be interpreted as having a limiting meaning. For example, some actions can be performed in different orders and / or simultaneously with other actions or events other than the actions or events shown and / or described herein. In addition, all the actions shown may not be required to implement one or more aspects or embodiments described herein. In addition, one or more actions depicted herein may be implemented in one or more separate actions and / or stages.

[0095] At act 2102, a plurality of trench structures are formed in a substrate. Each trench structure extends from a topmost surface of the substrate toward a bottommost surface of the substrate. Fig.9A and Fig. 9B A perspective view 900A and a cross-sectional view 900B are respectively shown of some embodiments corresponding to act 2102 .

[0096] A first dielectric layer is formed over the topmost surface of the substrate at act 2104. The first dielectric layer covers a plurality of inner surfaces of the substrate, the plurality of inner surfaces of the substrate defining a plurality of sidewalls of the plurality of trench structures. Fig. 10A and Fig. 10B A perspective view 1000A and a cross-sectional view 1000B are respectively shown of some embodiments corresponding to act 2104 .

[0097] At act 2106 , a semiconductor material is formed over the first dielectric layer. Fig.11A and Fig. 11B Some embodiments corresponding to act 2106 are shown in perspective view 1100A and cross-sectional view 1100B, respectively.

[0098] At act 2108, upper portions of the semiconductor material are removed such that upper surfaces of the semiconductor material are below upper surfaces of the first dielectric layer. Fig. 12A and Fig. 12B Some embodiments corresponding to act 2108 are shown in perspective view 1200A and cross-sectional view 1200B, respectively.

[0099] At act 2110, a second dielectric layer is formed over the semiconductor material. Fig.13A and Fig. 13B A perspective view 1300A and a cross-sectional view 1300B are respectively shown of some embodiments corresponding to act 2110 .

[0100] At act 2112 , a planarization process is performed to remove portions of the first dielectric layer and / or portions of the second dielectric layer, thereby exposing a topmost surface of the substrate. Fig.14A and Fig. 14BA perspective view 1400A and a cross-sectional view 1400B are respectively shown of some embodiments corresponding to act 2112 .

[0101] At act 2114, a third dielectric layer is formed over the second dielectric layer and / or the topmost surface of the substrate. Fig.15A and Fig. 15B Perspective view 1500A and cross-sectional view 1500B respectively illustrate some embodiments corresponding to action 2114 .

[0102] At act 2116, the third dielectric layer is patterned to selectively remove portions of the third dielectric layer from the topmost surface of the substrate. Fig.17A and Fig. 17B A perspective view 1700A and a cross-sectional view 1700B are shown of some embodiments corresponding to act 2116 .

[0103] At act 2118, portions of the substrate surrounding the semiconductor material are removed. Fig.19A Perspective view 1900A of some embodiments corresponding to action 2118 is shown.

[0104] Thus, the present disclosure relates to a method of forming a comb structure for a MEMS comb actuator using a self-aligned process to form a uniform dielectric liner structure that surrounds each protrusion of the comb structure, thereby successfully protecting each protrusion during manufacturing and electrically insulating each protrusion during operation. For example, the dielectric liner structure is made thin enough to prevent collision with another dielectric liner structure surrounding another comb structure during operation, and thick enough to provide sufficient electrical isolation for the protrusions of the comb structure by at least performing a planarization process and by forming an additional dielectric layer during the self-aligned process.

[0105] Therefore, in some embodiments, the present disclosure relates to a microelectromechanical system (MEMS) comb actuator, the MEMS comb actuator comprising: a comb structure comprising a support layer and a plurality of protrusions, the support layer comprising a first material, the plurality of protrusions comprising the first material and extending away from a first surface of the support layer in a first direction, wherein the plurality of protrusions are spaced apart along a second direction, the second direction being parallel to the first surface of the support layer; and a dielectric liner structure continuously and completely covering the first surface of the support layer and a plurality of outer surfaces of the plurality of protrusions, wherein the dielectric liner structure comprises a connecting portion, the connecting portion continuously connecting a plurality of topmost surfaces of at least two of the plurality of protrusions. In an embodiment, the connecting portion of the dielectric liner structure has a topmost surface that is a plane, and wherein a third direction perpendicular to the first direction and the second direction is orthogonal to the topmost surface of the connecting portion. In an embodiment, the connecting portion of the dielectric liner structure is spaced apart from at least one of the plurality of protrusions. In an embodiment, the comb structure also includes a fourth protrusion protruding from the first surface of the supporting layer in the first direction and spaced apart from the plurality of protrusions in the second direction, wherein the dielectric liner structure continuously and completely covers the plurality of outer surfaces of the fourth protrusion, and wherein a third protrusion among the plurality of protrusions is nearest to the fourth protrusion, wherein a first portion of the dielectric liner structure completely covers a first sidewall of the third protrusion, wherein a second portion of the dielectric liner structure completely covers a second sidewall of the fourth protrusion, and wherein an outermost wall of the first portion is spaced apart from an outermost wall of the second portion by a first distance, wherein the first distance is measured in the second direction, and wherein the first distance is approximately constant when measured in a third direction perpendicular to the first direction and the second direction. In an embodiment, a third portion of the dielectric liner structure covers a first sidewall of the fourth protrusion, wherein the third portion of the dielectric liner structure is spaced apart from the second portion of the dielectric liner structure by a second distance in the second direction, wherein the second distance is measured between the outermost wall of the second portion and the outermost wall of the third portion of the dielectric liner structure, and wherein the second distance is less than the first distance. In an embodiment, the dielectric liner structure comprises silicon dioxide.

[0106] In other embodiments, the present disclosure relates to a microelectromechanical system (MEMS) comb actuator, which includes: a comb structure, including a support layer and a first protrusion and a second protrusion, the support layer includes a semiconductor material, the first protrusion and the second protrusion include the semiconductor material, extend away from the support layer in a first direction, and are spaced apart from each other in a second direction orthogonal to the first direction; and a dielectric liner structure, arranged on the comb structure and including a first sidewall portion and a second sidewall portion, the first sidewall portion completely covering the first sidewall of the first protrusion, the second sidewall portion completely covering the second sidewall of the first protrusion, wherein the first sidewall portion and the second sidewall portion respectively have a uniform thickness measured in the second direction, and wherein the maximum distance of the dielectric liner structure surrounding the first protrusion and measured in the second direction is between the outer sidewall of the first sidewall portion facing away from the first protrusion and the outer sidewall of the second sidewall portion. In an embodiment, the comb structure further comprises a third protrusion comprising the semiconductor material and extending away from the support layer in the first direction, wherein the second protrusion is arranged between the first protrusion and the third protrusion. The dielectric liner structure further comprises a connecting portion directly connecting the topmost surface of the second protrusion to the topmost surface of the third protrusion, wherein the third direction is orthogonal to the topmost surface of the second protrusion and the topmost surface of the third protrusion, and wherein the third direction is perpendicular to the first direction and the second direction. In an embodiment, the connecting portion completely covers the topmost surface of the second protrusion and the topmost surface of the third protrusion. In an embodiment, the dielectric liner structure further comprises a top portion arranged on the topmost surface of the first protrusion, wherein the top portion couples the first sidewall portion to the second sidewall portion of the dielectric liner structure, wherein the third direction is orthogonal to the topmost surface of the first protrusion, wherein the third direction is perpendicular to the first direction and the second direction. In an embodiment, the second distance is equal to the maximum dimension of the top portion measured in the second direction, and wherein the second distance is approximately equal to the maximum distance. In an embodiment, the top portion of the dielectric liner structure comprises a first circular surface coupling a topmost surface of the top portion to the outer sidewall of the first sidewall portion, and wherein the top portion of the dielectric liner structure further comprises a second circular surface coupling the topmost surface of the top portion to the outer sidewall of the second sidewall portion. In an embodiment, the semiconductor material comprises polysilicon.

[0107] In some other embodiments, the present disclosure relates to a method for forming a comb-like structure, the method comprising: forming a plurality of groove structures in a substrate extending from the topmost surface of the substrate toward the bottommost surface of the substrate; forming a first dielectric layer above the topmost surface of the substrate, wherein the first dielectric layer covers a plurality of inner surfaces of the plurality of groove structures, and the plurality of inner surfaces of the groove structures are defined by a plurality of inner surfaces of the substrate; forming a semiconductor material above the first dielectric layer; removing a plurality of upper portions of the semiconductor material to form a comb-like structure including a plurality of protrusions within the plurality of groove structures; forming a second dielectric layer above the comb-like structure; performing a planarization process to remove a portion of the first dielectric layer and / or a portion of the second dielectric layer to expose the topmost surface of the substrate; forming a third dielectric layer above the second dielectric layer and / or above the topmost surface of the substrate; patterning the third dielectric layer to remove a plurality of portions of the third dielectric layer from the topmost surface of the substrate; and removing a plurality of portions of the substrate. In an embodiment, patterning the third dielectric layer comprises: forming a mask structure directly above at least two of the plurality of protrusions; performing an etching process to remove a plurality of portions of the third dielectric layer arranged above the topmost surface of the substrate, wherein the plurality of portions of the third dielectric layer are not covered by the mask structure; and removing the mask structure. In an embodiment, after performing the etching process, the topmost surface of the first dielectric layer, the topmost surface of the second dielectric layer, and the topmost surface of the third dielectric layer that are not directly below the mask structure do not extend above the topmost surface of the substrate. In an embodiment, the forming of the second dielectric layer comprises a thermal oxidation process. In an embodiment, the forming of the second dielectric layer comprises a chemical vapor deposition process. In an embodiment, after removing the plurality of upper portions of the semiconductor material, the plurality of topmost surfaces of the plurality of protrusions are located below the topmost surface of the substrate. In an embodiment, the first dielectric layer, the second dielectric layer, and the third dielectric layer comprise the same material.

[0108] The features of several embodiments are summarized above so that those skilled in the art can better understand the various aspects of the present disclosure. Those skilled in the art will understand that they can easily use the present disclosure as a basis for designing or modifying other processes and structures to implement the same purposes and / or achieve the same advantages as the embodiments described herein. Those skilled in the art will also recognize that these equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they can make various changes, substitutions and modifications herein without departing from the spirit and scope of the present disclosure.

Claims

1. A micro-electromechanical system comb actuator, comprising: Comb structure, including: a support layer comprising a first material, and a plurality of protrusions comprising the first material and extending in a first direction away from the first surface of the support layer, wherein the plurality of protrusions are spaced apart along a second direction parallel to the first surface of the support layer; and A dielectric liner structure continuously and completely covers the first surface of the support layer and multiple outer surfaces of the plurality of protrusions, wherein the dielectric liner structure includes a connecting portion, the connecting portion continuously connects multiple topmost surfaces of at least two protrusions among the plurality of protrusions, and wherein a third direction perpendicular to the first direction and the second direction is orthogonal to the topmost surfaces of the at least two protrusions among the plurality of protrusions.

2. The MEMS comb actuator of claim 1, wherein the connection portion of the dielectric pad structure has a topmost surface that is a plane, and wherein the third direction perpendicular to the first direction and the second direction is orthogonal to the topmost surface of the connection portion. 3 . The MEMS comb actuator of claim 1 , wherein the connecting portion of the dielectric pad structure is spaced apart from at least one protrusion of the plurality of protrusions.

4. The MEMS comb actuator according to claim 1, wherein the comb structure further comprises: a fourth protrusion protruding from the first surface of the support layer in the first direction and spaced apart from the plurality of protrusions in the second direction, wherein the dielectric liner structure continuously and completely covers a plurality of outer surfaces of the fourth protrusion, and wherein a third protrusion among the plurality of protrusions is most adjacent to the fourth protrusion, wherein a first portion of the dielectric liner structure completely covers a first sidewall of the third protrusion, wherein a second portion of the dielectric liner structure completely covers a second sidewall of the fourth protrusion, and wherein an outermost wall of the first portion is spaced apart from an outermost wall of the second portion by a first distance, wherein the first distance is measured in the second direction, and wherein the first distance is approximately constant when measured in a third direction perpendicular to the first direction and the second direction.

5. The MEMS comb actuator of claim 4 , wherein the third portion of the dielectric pad structure covers the first sidewall of the fourth protrusion, wherein the third portion of the dielectric pad structure is spaced apart from the second portion of the dielectric pad structure by a second distance in the second direction, wherein the second distance is measured between the outermost wall of the second portion and the outermost wall of the third portion of the dielectric pad structure, and wherein the second distance is less than the first distance.

6. The MEMS comb actuator of claim 4, wherein the dielectric spacer structure comprises silicon dioxide.

7. A micro-electromechanical system comb actuator, comprising: Comb structure, including: a support layer comprising a semiconductor material, and A first protrusion and a second protrusion, comprising the semiconductor material, extending away from the support layer in a first direction and spaced apart from each other in a second direction orthogonal to the first direction; and a dielectric liner structure arranged on the comb-like structure and comprising: a first side wall portion completely covering the first side wall of the first protrusion, a second side wall portion completely covering the second side wall of the first protrusion, and a top portion arranged on an upper surface of the first protrusion, wherein the first side wall portion and the second side wall portion each have a uniform thickness measured in the second direction, and wherein a maximum distance of the dielectric liner structure around the first protrusion and measured in the second direction is between an outer sidewall of the first sidewall portion facing away from the first protrusion and an outer sidewall of the second sidewall portion, wherein the top portion couples the first sidewall portion to the second sidewall portion of the dielectric liner structure, wherein a third direction is orthogonal to the upper surface of the first protrusion, wherein the third direction is perpendicular to the first direction and the second direction.

8. The MEMS comb actuator according to claim 7, wherein the comb structure further comprises: a third protrusion comprising the semiconductor material and extending away from the support layer in the first direction, wherein the second protrusion is arranged between the first protrusion and the third protrusion; and The dielectric liner structure further comprises: A connecting portion directly connects the upper surface of the second protrusion to the upper surface of the third protrusion, wherein a third direction is orthogonal to the upper surface of the second protrusion and the upper surface of the third protrusion, and wherein the third direction is perpendicular to the first direction and the second direction. 9 . The MEMS comb actuator according to claim 8 , wherein the connecting portion completely covers the upper surface of the second protrusion and the upper surface of the third protrusion.

10. The MEMS comb actuator of claim 7, wherein a second distance is equal to a maximum dimension of the top portion measured in the second direction, and wherein the second distance is equal to the maximum distance.

11. A MEMS comb actuator according to claim 7, wherein the top portion of the dielectric pad structure includes a first circular surface, which couples the upper surface of the top portion to the outer sidewall of the first sidewall portion, and wherein the top portion of the dielectric pad structure also includes a second circular surface, which couples the upper surface of the top portion to the outer sidewall of the second sidewall portion.

12. The MEMS comb actuator of claim 7, wherein the semiconductor material comprises polysilicon.

13. A method for forming a comb-like structure, comprising: forming a plurality of groove structures extending from the topmost surface of the substrate toward the bottommost surface of the substrate in a third direction in a substrate, wherein the topmost surface of the substrate and the bottommost surface of the substrate are coplanar with a plane orthogonal to the third direction; forming a first dielectric layer over the topmost surface of the substrate, wherein the first dielectric layer covers a plurality of inner surfaces of the plurality of trench structures, the plurality of inner surfaces of the trench structures being defined by a plurality of inner surfaces of the substrate; forming a semiconductor material over the first dielectric layer; removing a plurality of upper portions of the semiconductor material to form the comb-like structure including a plurality of protrusions within the plurality of trench structures, the substrate further comprising a support portion extending away from the trench structures in a first direction, the plurality of protrusions separating the trench structures from each other in a second direction, and the third direction being perpendicular to the first direction and the second direction; forming a second dielectric layer over the comb-like structure; performing a planarization process to remove a portion of the first dielectric layer and / or a portion of the second dielectric layer, thereby exposing the topmost surface of the substrate; forming a third dielectric layer over the second dielectric layer and / or over the topmost surface of the substrate; patterning the third dielectric layer to remove portions of the third dielectric layer from the topmost surface of the substrate; as well as Portions of the substrate are removed.

14. The method of claim 13, wherein patterning the third dielectric layer comprises: forming a mask structure directly over at least two protrusions of the plurality of protrusions; performing an etching process to remove portions of the third dielectric layer disposed above the topmost surface of the substrate, wherein the portions of the third dielectric layer are not covered by the mask structure; as well as The mask structure is removed.

15. The method of claim 14, wherein after performing the etching process, the topmost surface of the first dielectric layer, the topmost surface of the second dielectric layer, and the topmost surface of the third dielectric layer that are not located directly under the mask structure do not extend above the topmost surface of the substrate. The method of claim 13 , wherein the forming the second dielectric layer comprises a thermal oxidation process.

17. The method of claim 13, wherein the forming the second dielectric layer comprises a chemical vapor deposition process.

18. The method of claim 13, wherein after removing the plurality of upper portions of the semiconductor material, a plurality of topmost surfaces of the plurality of protrusions are located below the topmost surface of the substrate.

19. The method of claim 13, wherein the first dielectric layer, the second dielectric layer, and the third dielectric layer comprise a same material.

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