Patent ID: 12209014

REFERENCE NUMERALS

11—first lower protective layer;12—first substrate;13—first insulating layer;14—first device layer;15—first upper protective layer;16—electrode lead groove;17—insulating groove;18—lower comb plates;19—moving space groove;20—second device layer;21—second insulating layer;22—second substrate layer;23—frame;231—inner frame;232—outer frame;24—upper comb plates;25—movable micro light reflector;26—elastic beam;27—metal reflective layer;28—first upper comb plate electrode;29—first lower comb plate electrode;30—second upper comb plate electrode;31—second lower comb plate electrode;32—third lower protective layer;33—third device layer;34—third insulating layer;35—third substrate layer;36—third upper protective layer;37—lower comb plate electrode lead groove;38—fourth base;39—isolation groove;40—fifth device layer;41—fifth insulating layer;42—fifth substrate layer;43—sixth lower protective layer;44—sixth device layer;45—sixth insulating layer;46—sixth substrate layer;48—sixth upper protective layer.

DETAILED DESCRIPTION

The following describes the implementation of the present disclosure through specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the content disclosed in this specification.

Please refer toFIG.1˜FIG.29. It should be noted that the structure, ratio, size, etc. shown in the accompanying drawings in this specification are only used to illustrate the content disclosed in the specification for the understanding and reading of those familiar with this technology, and are not intended to limit the implementation of the present invention. Any structural modification, proportional relationship change or size adjustment should still fall within the scope of the present disclosure, given that no effect and objective achievable by the present disclosure are hindered. Terms such as “upper”, “lower”, “left”, “right”, “middle”, “first” and “second” used in this specification are only for ease of description, and they are not intended to limit the scope of implementation of the present invention. Any change or adjustment of corresponding relative relationships without any substantial technical change should be regarded as within the scope of the implementation of the present disclosure.

In a conventional electrostatic MEMS micro mirror array, its electrodes and reflectors are generally located on the upper and lower side of the array. Because the micro mirror array usually has a large area and the number of the electrodes is also large, if the electrodes are led out from the upper surface of the array, the device's performance will be impacted. So the electrodes are generally located on the lower surface of the device, and therefore the electrodes are usually led out from the lower surface during testing. However, this means, probes for wafer-level testing can only be located under the chip, which can't be achieved by existing testing equipment on the market, and during the testing a given voltage also needs to be applied to the lower surface of the device, which brings difficulties to the testing of the micro mirror array.

Embodiment 1

As shown inFIG.1, this embodiment provides a method for preparing a MEMS micro mirror with electrodes on both sides, which includes the following steps:providing a first base, whose structure is shown inFIG.2, which includes a first lower protective layer11, a first substrate12, a first insulating layer13, a first device layer14, and a first upper protective layer15sequentially stacked; forming an electrode lead groove16in the first base using a method such as photo lithographing etching, with the electrode lead groove16extending from the first lower protective layer11to a surface of the first device layer14, resulting in the structure as shown inFIG.3; In one embodiment, a cross section of the electrode lead groove16is a trapezoid, which means its opening area gradually decreases upwards from the first lower protective layer11; and the forming of the electrode lead groove16comprises: etching the first lower protective layer11and the first substrate12to form a first opening, and then removing the first insulating layer13corresponding to the first opening to form the electrode lead groove16exposing the first device layer14;removing the first upper protective layer15by methods including but not limited to etching so as to expose the first device layer14;in the first device layer14, forming an insulating groove17, a plurality of lower comb plates18that are spaced apart from each other, and a moving space groove19to obtain a bonded structure layer by methods including but not limited to photo lithographing etching, wherein the moving space groove19is between the plurality of lower comb plates18, the insulating groove17is inside or outside the moving space groove19, and the insulating groove17penetrates the first device layer14; specifically, openings corresponding to the moving space groove19and the insulating groove17are formed in the first device layer14by photo lithographic etching, to obtain the structure shown inFIG.4, then the openings are further etched to obtain the insulating groove17, the lower comb plates18and the moving space groove19, to obtain the structure shown inFIG.5; dividing the etching process into several steps helps to ensure the graphic quality of the etching; the moving space groove19provides moving space for comb plates and a movable micro light reflector25.providing a second base, which includes a second device layer20, a second insulating layer21, and a second substrate layer22sequentially stacked, wherein the second base is bonded to the bonded structure layer to obtain a bonded piece wherein a surface of the second device layer20and a surface of the first device layer14are bonding surfaces, as shown inFIG.6;removing the second substrate layer22, with the resulting structure shown inFIG.7, and then removing the second insulating layer21until the second device layer20is exposed; in the second device layer20, forming a frame23, a plurality of upper comb plates24that are spaced apart from each other, a movable micro light reflector25, and an elastic beam26by methods including but not limited to photo lithographing etching, wherein the movable micro light reflector25is located inside the frame23, the elastic beam26is connected to the frame23and/or the movable micro light reflector25(in the Specification, “connected” means “directly connected” and/or “indirectly connected”); the movable micro light reflector25is located above the moving space groove19; the projections of the upper comb plates24and the lower comb plates18on a horizontal plane are staggered, and the numbers of the upper comb plates24and the lower comb plates18are both more than one, such as three or more, in order to form multiple comb plates pairs; the widths of the upper comb plates24and the lower comb plates18may be the same or different; the resulting structure is shown inFIG.8;forming a metal reflective layer27, a first upper comb plate electrode28, a first lower comb plate electrode29, a second upper comb plate electrode30, and a second lower comb plate electrode31using methods including but not limited to sputtering, wherein the first upper comb plate electrode28and the first lower comb plate electrode29are located on a surface of the frame23, and the second upper comb plate electrode30and the second lower comb plate electrode31extend from the electrode lead groove16to a surface of the first substrate, wherein the first lower comb plate electrode29and the second lower comb plate electrode31are electrically connected to the lower comb plates18, and the first upper comb plate electrode28and the second upper comb plate electrode30are electrically connected to the upper comb plates24, and the resulting structure is shown inFIG.9; the materials of the metal reflective layer27and the electrodes include one or more of gold, silver, copper, and aluminum.

In the present disclosure, electrodes are arranged on the upper and lower sides of the MEMS micro mirror, and the probe and test system can be easily built on the chip during testing. Therefore, conventional test methods can be used without customized test equipment since the electrodes can still be led out from below when packaged, which can greatly improve testing and packaging flexibility of the chip.

In an embodiment, as shown inFIG.10, there are two elastic beams26(defined as a first elastic beam and a second elastic beam), the frame23is a single frame23, and the first elastic beam and the second elastic beam are located inside the frame23, and connect the frame23and the movable micro light reflector25along a first direction. The structure of this embodiment is relatively simple, but the movable micro light reflector25can only rotate in one direction. In order to improve the stability of the overall structure and the performance of the device, the size and shape of the two elastic beams26are preferably the same.

In another embodiment, as shown inFIG.11, the frame23includes an inner frame231and an outer frame232located at the periphery of the inner frame231, and the movable micro light reflector25is located in the inner frame231; the elastic beams26further include a third elastic beam and a fourth elastic beam. The third elastic beam and the fourth elastic beam are located between the inner frame231and the outer frame232, and connect the inner frame231and the outer frame232along a second direction with the second direction perpendicular to the first direction. In this embodiment, the movable micro light reflector25can be driven to rotate in two directions perpendicular to each other.

In order to further improve the performance of the device, as an example, the first elastic beam and the second elastic beam have the same shape and size; the third elastic beam and the fourth elastic beam have the same shape and size; and the elastic beams26are distributed symmetrically with movable micro light reflector25as the center.

As an example, both the first base and the second base include a silicon-on-insulator (SOI) substrate, that is, the first device layer14, the first substrate12, and the second device layer20may be silicon material layers; the first lower protective layer11, the second lower protective layer, the first insulating layer13, and the second insulating layer21may be silicon oxide layers; each protective layer provides protection for a corresponding device layer. Of course, in other examples, each device layer and substrate can also be made of semiconductor materials such as germanium, silicon germanium, silicon carbide, etc. The first lower protective layer11, the second lower protective layer, the first insulating layer13, and the second insulating layer21can also be made of other insulating material accordingly, and the second substrate layer22can be made of insulating materials such as glass, ceramics, semiconductor materials such as silicon, or a combination thereof.

The preparation method provided in this embodiment can be used to prepare a single MEMS micro mirror, and can also be used to prepare a MEMS micro mirror array, that is, to manufacture multiple MEMS micro mirrors at the same time, for example, to manufacture hundreds of or thousands of MEMS micro mirrors on a wafer at the same time. Especially when the method is used to make MEMS micro mirror arrays, its advantages are particularly prominent. For example,FIG.12shows a schematic diagram of the structure of a MEMS micro mirror array prepared by the method of this embodiment. Each micro mirror of the MEMS micro mirror array is as shown inFIG.9. In other words,FIG.9, in a sense, is an enlarged view of area A ofFIG.12.

It should be noted that the enumeration of above steps is only intended to describe the method of the present disclosure in more detail, and is not used to limit the order the steps can be carried out. In fact, the order of the steps can be adjusted, and some of the steps can be combined as needed. For example, when forming the insulating groove, the plurality of lower comb plates, and the moving space groove in the first device layer, each structure can be formed at the same time or successively.

Embodiment 2

This embodiment provides another method for preparing a MEMS micro mirror with electrodes on both sides. The main difference between this embodiment and Embodiment 1 is that, in Embodiment 1, there are several etching steps during the process of preparing the electrode lead groove16: the first lower protective layer11and the first substrate12are etched to form a first opening, and then the first insulating layer13corresponding to the first opening is removed to form the electrode lead groove16exposing the first device layer14; in Embodiment 2, when the first lower protective layer11and the first upper protective layer15are removed (or it may be provided that only includes the second device layer20, the second insulating layer21, and the second substrate layer22), the first substrate12and the first insulating layer13are then etched in the same etching step to form the electrode lead groove16exposing the first device layer14, during which an insulating groove17penetrating the first substrate12is formed in the first substrate12, and the resulting structure is shown inFIG.13. As an example, a cross section of the electrode lead groove16in this embodiment is a rectangle.

Except for the above differences, the other steps of the method, the material of each layer, and the processing technology of this embodiment are basically the same as those in Embodiment 1. For details, please refer to the content regarding Embodiment 1. The final structure of the MEMS micro mirror with electrodes on both sides prepared according to the method of this embodiment is shown inFIG.14. This embodiment can also be used to prepare a MEMS micro mirror array.

Embodiment 3

This embodiment provides another method for preparing a MEMS micro mirror with electrodes on both sides. The main difference between the method of this embodiment and Embodiment 1 is that, in this embodiment, while forming an insulating groove17, a plurality of lower comb plates18that are spaced away from each other, and a moving space groove19in a first device layer14, an upper lead groove is also formed in the first device layer14to form an electrode lead groove16, together with a lower lead groove formed in the first base; bonding surfaces during a subsequent bonding process are a surface of the first device layer14and a surface of an insulating layer (in Embodiment 1, the surfaces of the two device layers are the bonding surfaces). Specifically, the method of this embodiment includes the following steps:providing a first base, wherein the first base comprises a first lower protective layer11, a first substrate12, a first insulating layer13, a first device layer14, and a first upper protective layer15sequentially stacked; in the first base, forming a lower lead groove which extends from the first lower protective layer11to a surface of the first device layer14(seeFIGS.3-4);removing the first upper protective layer15;forming an insulating groove17, a plurality of lower comb plates18, an upper lead groove, and a moving space groove19in the first device layer14to obtain a bonded structure layer, wherein the moving space groove19is between the plurality of lower comb plates18, the insulating groove17and the upper lead groove may be located outside the moving space groove19(preferably, the insulating groove17is also located outside the upper lead groove, with the inside referring to the side close to the center of the corresponding layer), so that the upper lead groove and the insulating groove17penetrate the first device layer14, and the upper lead groove and the lower lead groove are connected head to tail to form an electrode lead groove16(the resulting structure is shown inFIG.15);providing a third base, wherein the third base comprises a third lower protective layer32, a third device layer33, a third insulating layer34, a third substrate layer35, and a third upper protective layer36sequentially stacked, wherein the third base and the bonded structure layer are bonded to obtain a bonded piece, wherein a surface of the third lower protective layer32of the third base and a surface of the first device layer14are bonding surfaces; the third base may include a silicon-on-insulator (SOI) substrate, that is, the third lower protective layer32, the third insulating layer34, and the third upper protective layer36may be made of silicon oxide, and the third device layer33may be made of silicon.removing the third upper protective layer36, the third substrate layer35, and the third insulating layer34, forming a frame23, upper comb plates24, a movable micro light reflector25, an elastic beam26and a lower comb plate electrode lead groove37in the third device layer33, wherein the movable micro light reflector25is located inside the frame23, the elastic beam26is connected to the frame23and/or the movable micro light reflector25, the movable micro light reflector25is above the moving space groove19, the lower comb plate electrode lead groove37penetrates the third device layer33and extends down to a surface of the first device layer14, and projections of the upper comb plates24and the lower comb plates18on a horizontal plane are staggered; the resulting structure is shown inFIG.17(the third upper protective layer36on a surface of the lower comb plates18needs to be removed);forming a metal reflective layer27, a first upper comb plate electrode28, a first lower comb plate electrode29, a second upper comb plate electrode30, and a second lower comb plate electrode31, wherein the first upper comb plate electrode28is located on a surface of the frame23, and the first lower comb plate electrode29is located inside the lower comb plates electrode lead groove37, wherein the second upper comb plate electrode30and the second lower comb plate electrode31extend from the electrode lead groove16to a surface of the first substrate12, wherein the first lower comb plate electrode29and the second lower comb plate electrode31are electrically connected with the lower comb plates18, and the first upper comb plate electrode28and the second upper comb plate electrode30are electrically connected with the upper comb plates24(the resulting structure is shown inFIG.18).

The method of this embodiment can be used to prepare a single MEMS micro mirror or multiple MEMS micro mirrors. When it is used to prepare multiple MEMS micro mirrors, that is, to prepare a MEMS micro mirror array, its advantages are particularly prominent.

Embodiment 4

This embodiment provides another method for preparing a MEMS micro mirror with electrodes on both sides, which includes the following steps:

providing a fourth base38, in which an isolation groove39is formed, wherein the isolation groove39may be a single groove or a plurality of grooves, and the isolation groove39extends along the longitudinal direction of the fourth base38; specifically, the fourth base38includes, but is not limited to, a semiconductor base such as a silicon base, and a photo lithographic etching method can be used to form an isolation opening in the fourth base38, and the resulting structure is shown inFIG.19, and then a deposition method or thermal oxidation method can be employed to form insulating material such as silicon oxide in the isolation groove39, and the resulting structure obtained is shown inFIG.20. Of course, in other examples, ion implantation can be used to form isolation belts in locations correspond to the isolation groove39.forming an insulating groove17, a moving space groove19, and a plurality of lower comb plates18on the side of the fourth base38away from the isolation groove39to obtain a pretreatment structure. The insulating groove17, the moving space groove19, and the plurality of lower comb plates18all extend along the longitudinal direction of the fourth base38, and the insulating groove17and/or the moving space groove19are in communication with the isolation groove39; Specifically, a photo lithographic etching can be used to form an opening corresponding to the insulating groove17and define the position of the moving space groove19, with the insulating groove17correspondingly located above the isolation groove39, to obtain the structure shown inFIG.21, after which the photo lithographic etching is continued to obtain the insulating groove17, the moving space groove19and a plurality of lower comb plates18, to obtain the structure shown inFIG.22.providing a fifth base, the fifth base comprising a fifth device layer40, a fifth insulating layer41, and a fifth substrate layer42sequentially stacked, bonding the fifth base to the pretreatment structure, wherein a surface of the moving space groove19with the opening and a surface of the fifth device layer40are bonding surfaces (the resulting structure is shown inFIG.23);removing the fifth substrate layer42and the fifth insulating layer41(the resulting structure is shown inFIG.24);forming a frame23, upper comb plates24, a movable micro light reflector25, and an elastic beam26in the fifth device layer40, with the movable micro light reflector25located inside the frame23, the elastic beam26connected to the frame23and/or the movable micro light reflector25, the movable micro light reflector25located above the moving space groove19, projections of the upper comb plates24and the lower comb plates18on a horizontal plane being staggered (the resulting structure is shown inFIG.25).forming a metal reflective layer27, the first upper comb plate electrode28, the second upper comb plate electrode30, the first lower comb plate electrode29, and the second lower comb plate electrode31by methods including but not limited to sputtering, with the metal reflective layer27located on a surface of the movable micro light reflector25, the first upper comb plate electrode28and the first lower comb plate electrode29located on a surface of the fifth device layer40, the second upper comb plate electrode30and the second lower comb plate electrode31located on a surface of the fourth base38away from the fifth device layer40, the first lower comb plate electrode29and the second lower comb plate electrode31both electrically connected to the lower comb plates18, the first upper comb plate electrode28and the second upper comb plate electrode30both electrically connected to the upper comb plates24(the resulting structure is shown inFIG.26)

In this embodiment, a single MEMS micro mirror or multiple MEMS micro mirrors can be prepared. When there are multiple MEMS micro mirrors, adjacent MEMS micro mirrors are electrically insulated by the isolation groove39.FIG.27shows a schematic diagram of the structure of a MEMS micro mirror array prepared by the method of this embodiment. Each micro mirror of the MEMS micro mirror array is as shown inFIG.26. In other words,FIG.26, in a sense, is an enlarged view of area A ofFIG.27.

Embodiment 5

This embodiment provides another method for preparing a MEMS micro mirror with electrodes on both sides. The main difference between the preparation method of this embodiment and Embodiment 4 is that, in Embodiment 4, when the fifth base and the pretreatment structure are bonded, the opening surface of the moving space groove19and the surface of the fifth device layer40are bonding surfaces; that is, the surfaces of the two semiconductor material layers are bonding surfaces, and each electrode is directly formed on a surface of a corresponding device layer. In this embodiment, a surface of an insulating layer and a surface of a semiconductor material layer are used as bonding surfaces, and electrode lead groove16extending to a surface of a device layer are also formed during subsequent etching. Specifically, the method of this embodiment includes the following steps:providing a fourth base38, and forming isolation grooves39in the fourth base38, with the isolation grooves39extending along a longitudinal direction of the fourth base38;forming an insulating groove17, a moving space groove19, and a plurality of lower comb plates18on the side of the fourth base38away from the isolation groove39to obtain a pretreatment structure. The insulating groove17, the moving space groove19, and the plurality of lower comb plates18all extend along the longitudinal direction of the fourth base38, and the insulating groove17and/or the moving space groove19are in communication with the isolation groove39(seeFIGS.19-22);forming a second upper comb plate electrode30and a second lower comb plate electrode31on a surface of the fourth base38away from the moving space groove19;providing a sixth base, wherein the sixth base comprises a sixth lower protective layer43, a sixth device layer44, a sixth insulating layer45, a sixth substrate layer46, and a sixth upper protective layer47sequentially stacked, wherein the sixth base and the pretreatment structure are bonded, wherein an opening surface of the moving space groove19and a surface of the sixth lower protective layer43are bonding surfaces (the resulting structure is shown inFIG.28);removing the sixth upper protective layer47, the sixth substrate layer46, and the sixth insulating layer45until the sixth device layer44is exposed;forming a frame23, upper comb plates24, a movable micro light reflector25, elastic beams26, a first upper comb plate electrode28lead groove16and a first lower comb plate electrode29lead groove16in the sixth device layer44, wherein the movable micro light reflector25is located inside the frame23, the elastic beams26are connected with the frame23and/or the movable micro light reflector25, and the movable micro light reflector25is located above the moving space groove19, wherein projections of the upper comb plates24and the lower comb plates18on a horizontal plane are staggered, wherein the first upper comb plate electrode28lead groove16and the first lower comb plate electrode29lead groove16extend along a longitudinal direction of the sixth device layer44to a surface of the fourth base38, wherein the sixth lower protective layer43on a surface of the lower comb plates18is removed;forming a metal reflective layer27, a first upper comb plate electrode28, a first lower comb plate electrode29, a second upper comb plate electrode30, and a second lower comb plate electrode31, wherein the metal reflective layer27is located on a surface of the movable micro light reflector25, wherein the first upper comb plate electrode28is located in the first upper comb plate electrode28lead groove16, and the first upper comb plate electrode28extends from the first upper comb plate electrode28lead groove16to a surface of the sixth device layer44, and the first lower comb plate electrode29is located in the first lower comb plate electrode29lead groove16, wherein the second upper comb plate electrode30and the second lower comb plate electrode31are located on a surface of the fourth base38away from the moving space groove19, wherein the first lower comb plate electrode29and the second lower comb plate electrode31are electrically connected to the lower comb plates18, and the first upper comb plate electrode28and the second upper comb plate electrode30are electrically connected to the upper comb plates24(the resulting structure is shown in theFIG.29).

In summary, the present disclosure provides a method for preparing a MEMS micro mirror with electrodes on both sides, which includes: providing a first base, wherein the first base comprises a first lower protective layer, a first substrate, a first insulating layer, a first device layer, and a first upper protective layer sequentially stacked; forming an electrode lead groove in the first base, wherein the electrode lead groove extends from the first lower protective layer to a surface of the first device layer; removing the first upper protective layer;in the first device layer, forming an insulating groove, a plurality of lower comb plates, and a moving space groove to obtain a bonded structure layer, wherein the moving space groove is between the plurality of lower comb plates, and the insulating groove penetrates the first device layer; providing a second base, comprising a second device layer, a second insulating layer, and a second substrate layer sequentially stacked, wherein the second base is bonded to the bonded structure layer to obtain a bonded piece, wherein a surface of the second device layer and a surface of the first device layer are bonded surfaces; removing the second substrate layer and the second insulating layer; in the second device layer forming a frame, a plurality of upper comb plates, a movable micro light reflector and an elastic beam, wherein the movable micro light reflector is located inside the frame, the elastic beam is connected to the frame and/or the movable micro light reflector, wherein the movable micro light reflector is located above the moving space groove, wherein projections of the upper comb plates and the lower comb plates on a horizontal plane are staggered;forming a metal reflective layer, a first upper comb plate electrode, a first lower comb plate electrode, a second upper comb plate electrode, and a second lower comb plate electrode, wherein the first upper comb plate electrode and the first lower comb plate electrode are located on a surface of the frame, and the second upper comb plate electrode and second lower comb plate electrode are located in the electrode lead groove, wherein the first lower comb plate electrode and second lower comb plate electrode are electrically connected to the lower comb plates, and the first upper comb plate electrode and the second upper comb plate electrode are electrically connected to the upper comb plates. In the present disclosure, electrodes are arranged on the upper and lower sides of the MEMS micro mirror, and the probe and test system can be easily built on the chip during testing. Therefore, conventional test methods can be used without customized test equipment since the electrodes can still be led out from below when packaged, which can greatly improve testing and packaging flexibility of the chip. The advantages of the invention are particularly prominent when it is used to prepare a MEMS micro mirror array. Therefore, the present disclosure effectively overcomes various shortcomings of the prior art and has a high industrial value.

The above-mentioned embodiments only exemplarily illustrate the principles and effects of the present disclosure, and are not used to limit the present disclosure. Anyone familiar with this technology can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present disclosure. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical concepts disclosed by the present disclosure should still be covered by the attached claims of the present disclosure.