KR100492772B1 - Scaning mirror with 2 degrees of freedom and manufacturing method thereof - Google Patents

Abstract

Fixed frame; A rotation frame spaced apart from the fixed frame by a predetermined interval and rotated by a predetermined angle about the first rotation axis; A mirror disposed at an inner side and spaced apart from the rotation frame by a predetermined angle about a second rotational axis perpendicular to the first rotational axis; Permanent magnets disposed under the rotating frame and the mirror; A rotation frame driving conductive line formed on the rotation frame and generating a first rotation force in the rotation frame; A mirror drive conductive line formed on the rotating frame and the mirror and generating a second rotational force to the mirror; A compensation conductive line insulated from the mirror driving conductive line at a position corresponding to the mirror driving conductive line formed in the rotation frame; A rotating frame spring connecting the fixed frame and the rotating frame; A two degree of freedom scanning mirror comprising a rotating spring and a mirror spring connecting the mirror and a method of manufacturing the same.

Description

2 SCANING MIRROR WITH 2 DEGREES OF FREEDOM AND MANUFACTURING METHOD THEREOF

The present invention relates to a two degree of freedom scanning mirror and a method of manufacturing the same.

In general, two-degree-of-freedom scanning mirrors manufactured by MEMS (Micro Electro Mechanical Systems) technology are already used in the existing optical scanning laser head market, such as laser image display devices, optical switching, two-dimensional and three-dimensional scanners. More research is being done as it is expected to enter in earnest in the near future.

Here, micro-electro-mechanical-systems (MEMS) are micro-electromechanical systems, such as central processing units (CPUs) and memories, which have been developed with the development of electronic circuits. It is a field that enables to manufacture micro mechanical structures of several mm size.

In particular, the optical MEMS field that combines optical and MEMS technology has been widely used in recent years for high-speed optical communication, device development for storing vast amounts of information, and small screens of portable telephones or personal digital assistants (PDAs) to home theater systems. It is applied to fields, such as a display apparatus. By device, all the individual devices used in existing optical systems such as mirrors, lenses, and prisms are manufactured as MEMS devices, and research for integrating various optical devices on one chip is also in progress. Among them, the scanning mirror based on MEMS has been widely researched to realize two degrees of freedom rotation away from the conventional one degree of freedom mirror research.

2 DOF scanning mirrors are expected to be used in confocal microscopes, barcode scanners, laser displays, optical coherence tomography (OCT), and scanning laser rangefinders. .

In general, two degrees of freedom scanning mirrors include a two-dimensional optical scanning system using two one degrees of freedom mirrors, two degrees of freedom mirror with a single drive, and two degrees of freedom mirror with an individual drive.

The two-dimensional optical scanning system using two one-degree of freedom mirrors is a method of constructing a two-dimensional optical scanning system by aligning two one-degree of freedom mirrors having a horizontal axis and a longitudinal axis of rotation. Not only is it easy to manufacture, it also controls two mirrors that are structurally independent, so it has the advantage of independent control at the same time. However, in the case of implementing a two-dimensional optical scanning system in which the rotation axes of the two 1 degree of freedom mirrors are perpendicular to each other, the volume of the system becomes large, and since each mirror has only one rotation axis, it is reflected from the first mirror. The light that comes out must go through a second mirror. In this process, the rotation angle of the two mirrors is limited by the size and distance of the two mirrors, and when it is out of the limited rotation angle, light flows out of the mirror. In addition, there is a disadvantage that the loss and error that occurs as the optical path is longer.

 A two degree of freedom mirror with a single drive is a case in which the rotating structure has two degrees of freedom, but the driving part is manufactured by taking a single drive that is simultaneously operated throughout the rotating structure rather than being operated individually on each axis of rotation. It is difficult to exclude complete independent control of the axis of rotation or interference between the axis of rotation.

 In a two degree of freedom mirror with separate drives, an individual drive means that the drive for generating the rotary motion is made separately for the two axes of rotation. However, a two degree of freedom mirror with separate drives does not necessarily mean independent control in which the interference between the rotational axes has completely disappeared. In this conventional embodiment, there is a two degree of freedom mirror in which a vertical head comb actuator is manufactured on the same substrate surface as the mirror, thereby eliminating interference between rotational axes. This is done by adopting a vertical head comb actuator at both edges of the mirror and the rotating frame to pull left and right alternately. Between the mirror and the rotating frame is electrically insulated by an oxide film, and the parts that need to be mechanically connected are connected using polycrystalline silicon. While the hair comb electrode is far away in the vertical direction, the pulling force of the mirror does not work, and rotation occurs due to the rotational inertia force and the spring restoring force. However, since the force acts intensively while the electrode array of the rotor passes between the head comb arrays of the fixed part, the driving voltage signal operates only in the region higher than the resonant frequency of the rotor. Decreases. On the driving mechanism, there is a limit to obtaining a large rotation angle.

   In another conventional embodiment, there is a mirror in which copper is plated on a silicon wafer to make a planar coil, and a Lorentz force is induced in an external magnetic field. Both the mirror and the spring are made of silicon and the magnetic field is applied from the outside with a permanent magnet. Two pairs of permanent magnets must be arranged to the left and right of each axis of rotation to achieve two degrees of freedom rotation. Although the mirror and the rotating frame have their respective drive current circuits, interference rotation that occurs as the mirror's current circuit passes through the rotating frame is inevitable.

As described above, the conventional two degrees of freedom scanning mirror has a limitation in the rotation angle, and it is difficult to exclude the interference between the rotation axis and the complete independent control of the two rotation axes. In addition, the conventional two-DOF scanning electromagnetic force driving method has a problem that the space occupied by the entire scanning mirror increases because two pairs of permanent magnets are required separately.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a two-degree-of-freedom silicon scanning mirror of an electromagnetic force driving method having extremely low interference between two rotation axes.

In order to achieve the above object, the two degree of freedom scanning mirror of the present invention comprises: a fixed frame; A rotating frame spaced apart from the fixed frame at a predetermined interval and rotated by a predetermined angle about a first rotation axis; A mirror disposed at an inner side and spaced apart from the rotating frame by a predetermined angle, the mirror rotating at a predetermined angle about a second rotational axis perpendicular to the first rotational axis; A permanent magnet disposed under the rotating frame and the mirror; A rotation frame driving conductive line formed on the rotation frame and generating a first rotation force to the rotation frame; A mirror driving conductive line formed on the rotating frame and the mirror and generating a second rotational force to the mirror; A compensation conductive line insulated from the mirror driving conductive line at a position corresponding to the mirror driving conductive line formed in the rotation frame; A rotating frame spring connecting the fixed frame and the rotating frame; It is preferable to include a mirror spring connecting the rotating frame and the mirror.

In addition, it is preferable that a current flows in the compensation conductive line in a direction opposite to a current flowing in the mirror driving conductive line formed in the rotating frame.

In addition, the rotation frame spring is a portion where a part of the rotation frame driving conductive line, the compensation conductive line and the mirror driving conductive line overlap, and preferably includes a rotation frame driving conductive line portion, a compensation conductive line portion and a mirror driving conductive line portion. Do.

Moreover, it is preferable that the 1st insulating layer is formed in a part of the bottom face of the said rotating frame drive conductive wire part of the said rotating frame spring.

In addition, it is preferable that a third insulating layer is formed between the second insulating layer, the compensation conductive line portion, and the mirror driving conductive line portion between the rotation frame driving conductive line portion and the compensation conductive line portion.

In addition, the mirror spring preferably includes a mirror drive conductive line portion, wherein the mirror drive conductive line is a portion connecting the rotating frame and the mirror.

In addition, it is preferable that first, second and third insulating layers are continuously formed on a part of the bottom surface of the mirror drive conductive line portion of the mirror spring.

In addition, the first and second insulating layers are preferably oxide films.

In addition, the third insulating layer is preferably a polymer.

In addition, the third insulating layer is preferably a silicon oxide film.

In addition, it is preferable that the rotation frame spring is a pair of rotation frame drive conductive line portions, compensation conductive line portions, and mirror drive conductive lines which are spaced apart from each other by a predetermined interval.

It is also preferable that the mirror spring is a pair of mirror drive conductive lines which are spaced apart from each other by a predetermined distance.

In addition, the mirror driving conductive line and the compensation conductive line are preferably connected through a connection pad formed on the fixed frame.

In addition, it is preferable that the rotation frame driving current input pad and the output pad connected to the rotation frame driving conductive line are formed on the fixed frame.

In addition, it is preferable that a mirror driving current input pad and an output pad connected to the mirror driving conductive line are formed on the fixed frame.

In addition, the fixed frame, the rotating frame and the mirror is preferably silicon.

In addition, the mirror drive conductive line, the rotation frame drive conductive line and the compensation conductive line are preferably aluminum.

In addition, it is preferable that a first conductive layer is formed on the upper surfaces of the fixed frame, the rotating frame, and the mirror.

In order to achieve the above object, a method of manufacturing a two degree of freedom scanning mirror of the present invention includes forming a silicon layer on a substrate; Depositing a first conductive layer on the silicon layer, and etching the first conductive layer to have a rotation through hole exposing a periphery of the silicon layer to form a rotation frame etching mask, and simultaneously the first conductive layer is Etching to have a mirror through hole exposing a center portion of the silicon layer to form a mirror etching mask; Forming a first insulating layer on the rotating frame etching mask and the mirror etching mask; Depositing a second conductive layer on the first insulating layer and etching the second conductive layer to form a rotation frame driving conductive line; Forming a second insulating layer on the rotating frame driving conductive line and the first insulating layer; Depositing a third conductive layer on the second insulating layer and etching the third conductive layer to form a compensation conductive line; Forming a third insulating layer on the compensation conductive line and the second insulating layer; Depositing a fourth conductive layer on the third insulating layer and etching the fourth conductive layer to form a mirror driving conductive line; Etching the mirror driving conductive line, the rotating frame driving conductive line as a mask to form a rotation through hole exposing a periphery of the silicon layer, and a mirror through hole exposing a center portion of the silicon layer; The silicon layer is etched using the rotating frame mask and the mirror mask as a mask to form a fixed frame, a rotating frame and a mirror, and a rotating frame spring connecting the fixed frame and the rotating frame, and a mirror connecting the rotating frame and the mirror. It is preferred to include the step of forming a spring.

In addition, the first to fourth conductive layers are preferably made of aluminum.

The first insulating layer and the second insulating layer are preferably formed of an oxide film.

In addition, the third insulating layer is preferably formed of a polymer.

The method may further include planarizing the third insulating layer after forming the third insulating layer.

In addition, the third insulating layer is preferably formed of a silicon oxide film.

The method may further include forming a support part of the substrate by etching the central portion of the substrate after forming the silicon layer.

In addition, the etching of the silicon layer is preferably isotropic dry etching.

In addition, the etching of the silicon layer is preferably anisotropic dry etching.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like parts are designated by like reference numerals throughout the specification. When a part of a layer, film, region, plate, etc. is said to be "on" another part, this includes not only the other part being "right over" but also another part in the middle. On the contrary, when a part is "just above" another part, there is no other part in the middle.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic diagram of a two-degree-of-freedom scanning mirror of an electromagnetic force driving method, and FIG. 2 is an exploded view of a permanent magnet, a mirror drive conductive line, a compensation conductive line, a rotating frame drive conductive line, a mirror, a rotating frame, and a fixed frame. Is shown. 3A to 3D are cross-sectional views taken along the lines II ′, II-II ′, III-III ′, and IV-IV ′ of FIG. 1, respectively.

1 and 2, the two degree of freedom scanning mirror according to the first exemplary embodiment of the present invention is a fixed frame 10 and a rotating frame 20 which is disposed inwardly at a predetermined interval from the fixed frame 10. And a mirror 30 spaced apart from the rotation frame 20 by a predetermined interval. Then, the permanent magnet 40 is disposed on the rotating frame 20 and the mirror 30 spaced apart from the rotating frame 20 and the mirror 30 by a predetermined interval.

A portion of the upper surface of the rotating frame 20 is formed with a rotating frame driving conductive line 50, which generates a first rotational force in the rotating frame 20. In addition, a mirror driving conductive line 60 is formed on a part of the upper surface of the rotating frame 20 and the mirror 30, which generates a second rotational force on the mirror 30. The compensation conductive line 70 is formed to correspond to the mirror driving conductive line 60 formed on the rotation frame 20. It is formed below the outline of the mirror drive conductive line 60 formed in the rotating frame 20.

The fixed frame 10 and the rotating frame 20 are connected by the rotating frame spring 80, and the rotating frame 20 and the mirror 30 are connected by the mirror spring 90. The central axis of the rotating frame spring 80 is the first rotation axis to rotate the rotating frame 20, the central axis of the mirror spring 90 is the second rotation axis to rotate the mirror 30.

A detailed description will be given below with reference to FIGS. 1 to 6.

The fixed frame 10, the rotating frame 20, and the mirror 30 constituting the two degrees of freedom scanning mirror 30 of the present invention are formed of silicon. In the case of the scanning mirror, since it has a relatively long optical path compared to the switch mirror, the light reflected from the scanning mirror is diffracted. The angle at which such diffraction occurs becomes larger as the numerical aperture of the mirror becomes smaller, resulting in a decrease in resolution in recognition of an image or display of an image. Therefore, the size of the scanning mirror has a lower limit determined by the resolution, and the scanning mirror is designed with a size of 1 mm or more. That is, as shown in FIG. 4, the preferred size of the mirror 30 is 3.5 mm ² , and the size of the rotating frame 20 is 5.7 mm ² .

As shown in FIG. 4, the rotating frame 20 and the mirror 30, which are two rotating bodies, have a butterfly shape, and the rotating frame 20 and the mirror 30 are formed around two rotation axes X and Y. ) Is supposed to rotate. The rotating frame 20 has a concave first groove 21 at the center of the upper side and the lower side. And the mirror 30 has the 2nd groove | channel 31 concave in the center part of the left side and the right side. The first groove 21 and the second groove 31 are formed to maintain the rigidity of the rotating frame spring 80 and the mirror spring 90 to be described later, and to facilitate the action of the spring. As shown, in the first embodiment of the present invention, the rotating frame 20 and the mirror 30 such that the horizontal size of the first groove 21 is 0.9 mm and the horizontal size of the second groove 31 is 0.6 mm. To produce. The rotation frame 20 rotates a predetermined angle about the first rotation axis Y passing through the center of the first groove 21. Then, the mirror 30 is rotated by a predetermined angle about the second rotation axis X passing through the center of the second groove 31.

 In order to rotate without friction, the fixed frame 10 is spaced apart from the rotating frame 20 by a predetermined interval, and the connection of the fixed frame 10 and the rotating frame 20 is by the rotating frame spring 80. In addition, the rotation frame 20 and the mirror 30 are spaced apart by a predetermined interval, and the connection of the rotation frame 20 and the mirror 30 is made by the mirror spring 90. Here, the empty space between the fixed frame 10 and the rotating frame 20 is called the rotating through hole 3a, and the empty space between the rotating frame 20 and the mirror 30 is called the mirror through hole 3b.

The central axis of the rotating frame spring 80 becomes the first rotation axis Y, and the central axis of the mirror spring 90 becomes the second rotation axis X. As shown, in the first embodiment of the present invention, the distance between the fixed frame 10 and the rotating frame 20 is 0.1 mm, and the distance between the rotating frame 20 and the mirror 30 is fixed to 0.1 mm. The frame 10, the rotating frame 20, and the mirror 30 are produced.

A support 100 for supporting the two degrees of freedom scanning mirror is formed on the bottom of the fixed frame 10. The support 100 is preferably formed of glass.

As shown in Figs. 1, 3A to 3D, the upper surface of the rotating frame 20 and the mirror 30 of the two degree of freedom scanning mirror of the present invention for rotating the rotating frame 20 and the mirror 30 The conductive lines 50, 60, and 70 are formed to allow the driving current to flow. That is, the rotation frame driving conductive line 50, the mirror driving conductive line 60, and the compensation conductive line 70 for eliminating interference rotation are respectively driven to drive the rotation frame 20 and the central mirror 30 in the peripheral portion, respectively. Have. The bottom surfaces of the rotating frame 20 and the mirror 30 serve as reflecting surfaces for reflecting light. Permanent magnets 40 are arranged on the rotating frame 20 and the mirror 30 so as to apply a radial magnetic field to the rotating frame 20 and the mirror 30. That is, the magnetic fields applied to the conductive lines are all in the radial direction (B direction, shown in FIG. 5).

The mirror drive conductive line 60 for applying the mirror driving current for driving the mirror 30, the rotation frame driving conductive line 50 for applying the rotating frame driving current for driving the rotating frame 20, and the compensation current The compensation conductive lines 70 to be applied are made of different aluminum layers, and are insulated by an oxide film (SiO ₂ ) and a polymer layer (BCB, benzocyclobutanes). 2, each of these conductive lines is decomposed.

5 shows conductive lines and current flow formed on the upper surface of the rotating frame 20 and the mirror 30.

As indicated by the arrows in FIG. 5, the current 5 flowing along the rotating frame driving conductive line 50 is a current for driving the rotating frame 20, and the current 6 flowing along the mirror driving conductive line 60. Denotes a current for driving the mirror 30.

Since the mirror drive conductive line 60 is partially formed on the upper surface of the rotating frame 20, the mirror driving current 6 inevitably passes through the rotating frame 20. Due to this, when the mirror 30 is rotated, Lorentz force is also induced to the rotating frame 20, and the rotating frame 20 has an interference rotation. In order to prevent this, a compensation conductive line 70 is formed.

6 shows a compensation current flow diagram for canceling interference rotation. In order to prevent interference rotation of the rotating frame 20 when the mirror 30 is driven, a compensation conductive line 70 as shown in FIG. 6 is added. The compensation conductive line 70 is located directly below the mirror driving conductive line 60 formed in the rotation frame 20. The mirror drive conductive line 60 is formed on both the rotating frame 20 and the upper surface of the mirror 30. Among them, a compensation conductive line 70 is formed directly below the mirror driving conductive line 60 formed in the rotation frame 20. That is, the compensating current 7 flowing through the compensating conductive line 70 is always the opposite direction current having the same magnitude as the mirror driving current 6 flowing through the mirror driving conductive line 60 formed in the rotation frame 20, and thus interferes with it. Let the Lorentz forces causing the rotation cancel out.

3D is a cross-sectional view of the rotating frame spring. As shown in FIG. 3D, the rotation frame spring 80, which is a portion where the rotation frame drive conductive line 50, the compensation conductive line 70, and the mirror drive conductive line 60 overlap, rotates with the fixed frame 10. The frame 20 is connected. The rotating frame springs 80 form a multilayered spring pair. This is a structure in which two springs, each composed of a multilayer conductive layer and an insulating layer, have a narrow gap between them. This is because when the rotation frame drive conductive line 50, the compensation conductive line 70, and the mirror drive conductive line 60 are horizontally disposed for electrical insulation, the width of the spring becomes wider and the rotational movement characteristics become worse. It is a proposed structure. This rotation frame spring is an important factor that determines the rotation angle of the rotation frame 20.

9 illustrates a connection pad, a rotation frame driving current input / output pad, a mirror driving current input / output pad, and a connection pad.

The mirror drive conductive line 60 and the compensation conductive line 70 are connected in series through a connection pad 700 on the fixed frame 10. Thus, two independent alternating current sources are required to drive the two degrees of freedom scanning mirror of the present invention independently on two axes of rotation, and no additional current source for compensation current is required.

In addition, the rotating frame driving current input pads and the output pads 501 and 502 connected to the rotating frame driving conductive line 50 are formed on the fixed frame 10. In addition, mirror driving current input pads and output pads 601 and 602 connected to the mirror driving conductive line 60 are formed on the fixed frame 10.

7 and 8 show the shapes of the rotating frame spring pair of the multilayer structure and the mirror spring pair of the multilayer structure.

7 is a schematic view of a rotating frame spring 80 connecting the rotating frame 20 to the stationary frame 10. Several layers of conductive layers sandwiched between insulating films are made equal to a pair of springs, and on an electrical circuit they have a parallel circuit structure.

The rotating frame spring 80 includes the first insulating layer 110, the rotating frame driving conductive line part 50a, the second insulating layer 120, the compensation conductive line part 70a, the third insulating layer 130, and the mirror. The drive conductive line part 60a is formed in order from the bottom. Since the rotation frame spring 80 connects the fixed frame 10 and the rotation frame 20 spaced apart from each other by a predetermined interval, an empty space is formed at the bottom of the rotation frame spring 80. That is, one end of the rotating frame spring 80 is connected to the fixed frame 10 and the other end of the rotating frame spring 80 is connected to the rotating frame 20, the fixed frame 10 and the rotating frame 20 An intermediate portion of the rotating frame spring 80 is formed in the first through hole 3a of the liver.

As shown in FIGS. 3A to 3D, the first insulating layer 110 is formed on the upper surface of the fixed frame mask 3c, the rotation frame mask 3d, and the mirror mask 3e. The fixed frame mask 3c, the rotating frame mask 3d and the mirror mask 3e are aluminum layers used as masks to form the rotating frame 20 and the mirror 30, and the fixed frame 10, the rotating frame It is formed in the upper surface of the 20 and the mirror 30. The first insulating layer 110 is preferably formed of an oxide film. The first insulating layer 110 is not formed in the middle of the rotating frame spring 80 formed in the first through hole 3a between the fixed frame 10 and the rotating frame 20.

The rotation frame driving conductive line part 50a is formed on the first insulating layer 110. The rotating frame driving conductive line part 50a is a part connecting the rotating frame 20 and the fixed frame 10 as part of the rotating frame driving conductive line 50.

The second insulating layer 120 is formed on the rotation frame driving conductive line part 50a. The second insulating layer 120 is preferably formed of an oxide film.

The compensation conductive line part 70a is formed on the second insulating layer 120. The compensation conductive line part 70a is a part connecting the rotating frame 20 and the fixed frame 10 as part of the compensation conductive line 70.

The third insulating layer 130 is formed on the compensation conductive line part 70a. The third insulating layer 130 is preferably formed of a polymer. In the first embodiment of the present invention, benzocyclobutene (BCB) is used as the polymer. This is useful as a material of a low speed mirror because of easy flattening and small strength.

The mirror driving conductive line part 60a is formed on the third insulating layer 130. The mirror drive conductive line part 60a is a part which connects the rotation frame 20 and the fixed frame 10 as a part of the mirror drive conductive line 60.

As shown in Fig. 7, the pairs of conductive layers of the same layer in the pair of springs allow current in the same direction to flow. However, the current direction between the upper and lower conductive layers does not always coincide because the rotation frame driving current 5, the compensation current 7, and the mirror driving current 6 are applied at independent frequencies.

Lateral etching occurs during silicon dry etching through the intervals 85 between the pair of rotating frame springs 80 to shorten the process time and simultaneously reduce the thickness of the rotating mirror 30 and the rotating frame 20. The advantage is that it can be reduced.

8 shows a pair structure of mirror springs connecting the mirror 30 to the rotating frame 20. The mirror spring 90 has a single conductive layer thereon. Since the first to third insulating layers 110, 120, and 130 are deposited together in an insulating process between the conductive line layers on the rotating frame spring 80, a thick insulating layer is formed.

 As for the mirror spring 90, the 1st insulating layer 110, the 2nd insulating layer 120, the 3rd insulating layer 130, and the mirror drive conductive line part 60b are formed in order from the bottom. Since the mirror spring 90 connects the rotating frame 20 and the mirror 30 spaced apart from each other by a predetermined interval, the bottom surface of the mirror spring 90 has an empty space. That is, one end of the mirror spring 90 is connected to the rotating frame 20, the other end of the mirror spring 90 is connected to the mirror 30, and a second penetration between the rotating frame 20 and the mirror 30 is performed. The middle part of the mirror spring 90 is formed in the sphere 3b.

The first insulating layer 110 is formed on the upper surface of the fixed frame mask 3c, the rotating frame mask 3d, and the mirror mask 3e. The fixed frame mask 3c, the rotating frame mask 3d, and the mirror mask 3e are aluminum layers used as masks to form the rotating frame 20 and the mirror 30, and the fixed frame 10, the rotating frame It is formed in the upper surface of the 20 and the mirror 30. The first insulating layer 110 is preferably formed of an oxide film.

The second insulating layer 120 is formed on the first insulating layer 110. The second insulating layer 120 is preferably formed of an oxide film. The first insulating layer 110 and the second insulating layer are not formed in the middle portion of the mirror spring 90 formed in the second through hole 3b between the rotating frame 20 and the mirror 30.

The third insulating layer 130 is formed on the second insulating layer 120. The third insulating layer 130 is preferably formed of a polymer. In the first embodiment of the present invention, benzocyclobutene (BCB) is used as the polymer. This is useful as a material of a low speed mirror because of easy flattening and small strength.

The mirror driving conductive line part 60b is formed on the third insulating layer 130. The mirror drive conductive line part 60b is a part which connects the rotating frame 20 and the mirror 30 as a part of the mirror drive conductive line 60.

An input current and an output current 6 for driving the mirror flow through the pair of mirror drive conductive line portions 60b flowing over the mirror spring 90, and the current direction always flows in the opposite direction. Therefore, the insulation between these two conductive wires is very important. In addition, the spacing 95 between the pair of mirror springs allows the lateral etching in the silicon isotropic dry etching to proceed quickly so that the structure is undercut.

The two degree of freedom scanning mirror according to the first embodiment of the present invention having the rotating frame spring 80 and the mirror spring 90 in which the polymer is used is a low speed mirror. The low speed mirror has a resonant frequency of 1 kHz or less, but the rotational angle is large due to the low strength of the spring. In other words, because of the small strength of the spring, not only the rotation angle is large during resonance, but also a large rotation angle can be obtained in the static driving mode and the non-resonant driving mode.

   In the two-degree-of-freedom scanning mirror of the present invention, as shown in FIG. 5, since the driving current flows directly into the rotating frame 20, there is no interference rotation problem. However, the mirror drive current 6a indicated by the bold arrow in FIG. 5 reaches the mirror 30 via the rotating frame 20, so if there is no compensation current 7 as shown in FIG. ) When driving, an interference phenomenon in which the rotating frame 20 rotates together occurs. In the rotation of the mirror 30, the interference of the rotation frame 20 is represented by the distance ratio to the rotation axis in the static drive, and the interference rotation magnitude is determined in accordance with the gain ratio at the drive frequency in the dynamic drive. In the dynamic drive, the farther the resonant frequencies of the mirror 30 and the rotating frame 20 are from each other, the smaller the interference rotation size is, but not completely eliminated. Especially in non-resonant mode the interference rotation is still large and this interference rotation can be eliminated by the compensation current 7.

 The electromagnetic force driving method used in the first embodiment of the present invention can obtain a large force compared to the electrostatic power, so that the rotation angle or the vertical displacement is relatively very large, and low-voltage, low-power driving is easy. In addition, since there is no pull-in effect as in the case of constant power driving, analog operation is possible, and both manpower and repulsive force are available.

The operation of the two degree of freedom scanning mirror of the first embodiment according to the present invention configured as described above is as follows.

The two-degree-of-freedom scanning mirror of the electromagnetic force driving method of the present invention generates a rotational force by using a Lorentz force acting on the conductive line in the magnetic field. Therefore, low power, low voltage driving is possible.

In FIG. 5 there is a rotating frame 20 in a magnetic field radially from the center, showing the Lorentz force acting on the conductive line on the rotating frame 20. When the two currents flowing at both edges of the rotating frame 20 are in the same direction, the Lorentz forces induced at both edges are induced in opposite directions by Fleming's left-hand rule, and thus the rotating frame 20 is formed in the first direction. The rotary motion is performed about the rotation axis (Y). In FIG. 5, the Lorentz force is induced to the rotation frame driving conductive line 50c on the right side, and the Lorentz force is induced to the rotation frame driving conductive line 50d on the left side below the ground. Rotate in the direction as shown in FIG.

FIG. 5 also shows the Lorentz force acting on the conducting line on the mirror 30 frame with the mirror 30 in a magnetic field radially from the center. When the two currents flowing at both edges of the mirror 30 are in the same direction, the Lorentz forces induced at both edges are induced in opposite directions by Fleming's left-hand rule, so that the rotation frame 20 is rotated by the second rotation axis. Make a rotational movement about (X). The second rotation axis X is orthogonal to the first rotation axis Y and rotates at a predetermined angle. That is, in FIG. 5, the Lorentz force is induced to the upper mirror drive conductive line 60c in the direction above the ground, and the Lorentz force is induced to the lower mirror drive conductive line 60d in the direction below the ground. Rotate in the direction shown in 5.

In this case, in order to prevent the interference rotation of the rotating frame 20 generated because a part of the mirror driving conductive line 60e is formed on the rotating frame 20, the compensating conductive line 70 is part of the mirror driving conductive line 60e. It is formed under). Thus, the rotating frame 20 and the mirror 30 rotate independently without interference rotation.

A method of manufacturing a two degree of freedom scanning mirror according to a first embodiment of the present invention is shown in Figs. 10A to 10K.

 As shown in FIG. 10A, a silicon on glass (SOG) in which silicon 1 and glass 100 are bonded is used to manufacture a two degree of freedom scanning mirror according to the first embodiment of the present invention. This is because a large selectivity can be obtained in the process of processing both sides of the substrate.

The mirror 30 and the rotating frame 20 of the two degree of freedom scanning mirror of the present invention are made of silicon 1, and the lower support part is made of a glass substrate 100. Since the thickness of the mirror 30 and the rotating frame 20 is determined from the initial substrate thickness, the silicon substrate 1 and the glass substrate 100 are bonded to each other, and then the thickness of the silicon substrate 1 is processed to fit the design dimensions. The silicon substrate used is a silicon substrate in the <100> crystal direction, and the glass substrate is a corning glass substrate.

The thickness processing of a silicon substrate after substrate bonding uses the potassium hydroxide aqueous solution as a wet etching solution. The etchant heated 30 wt% aqueous potassium hydroxide solution at 80 ° C. showed an etching rate of 0.9 μm / min in the <100> crystal direction of silicon. Through chemical mechanical polishing (CMP), the surface of the silicon substrate roughened by wet etching was mirrored and the final design thickness was matched. In the wet etching process, the thickness of 20 μm was processed through the CMP process, and the silicon thickness within 3 μm and the uniformity of the substrate within 4.3% were realized based on the design thickness of 70 μm.

 Next, as shown in FIG. 10B, a glass wet etching process is performed. The glass used in this process is Corning # 7440 glass, which is wet etched with hydrofluoric acid. Glass is an amorphous material and exhibits isotropic etching. The etching mask uses a thin layer of thermally deposited chromium and gold and three layers with a thick film sensitizer on it. In the case of thermal deposition of chromium and gold, the substrate is heated and deposited at 180 ° C. to improve adhesion of the deposited metal thin film. Chromium is used as an adhesive layer for the adhesion of gold. The deposited chromium has a thickness of 1000 kPa and the deposition thickness of gold is 5000 kPa. A thick photoresist THB 430N (JSR) was used to perform a photolithography process of chromium and gold thin films, and was used as a top layer etching mask for glass etching. The main component of THB430N is acrylic, which shows excellent chemical resistance in acid solution compared to other thick film photosensitive agents after thermoplasticity and excellent adhesion to substrate. In addition, the stress is so small that there is almost no deformation of the pattern or bending of the substrate.

  The heat treatment after the photographing process was performed for 20 minutes on a 110 ℃ hot plate. After development and heat treatment of THB430N, gold is exposed on the bottom of the portion to be etched, and gold and chromium are sequentially etched, and then glass etching is performed using 49% hydrofluoric acid. An etching time of 120 minutes is required for a 500 μm thick glass substrate, and the silicon film on the opposite side is finally exposed. The actual silicon bottom was exposed to 100 minutes, but it took another 20 minutes to completely remove the etch byproducts of the glass remaining on the silicon surface.

  Next, as shown in FIG. 10C, the first conductive layer 3A is deposited on the silicon layer 1.

As shown in FIG. 10D, the first conductive layer 3A is etched to have the rotation through hole 3a exposing the periphery of the silicon layer 1 to fix the fixed frame etching mask 3c and the rotation frame etching. The mask 3d is formed, and at the same time, the first conductive layer 3A is etched to have the mirror through hole 3b exposing the center portion of the silicon layer 1 to form the mirror etch mask 3e.

10E, the first insulating layer 110A is formed on the fixed frame etching mask 3c, the rotation frame etching mask 3d, and the mirror etching mask 3e.

As shown in FIG. 10F, a second conductive layer is deposited on the first insulating layer 110A, and the second conductive layer is etched to form the rotation frame driving conductive line 50.

As illustrated in FIG. 10G, a second insulating layer 120A is formed on the rotation frame driving conductive line 50 and the first insulating layer 110A.

As shown in FIG. 10H, a third conductive layer is deposited on the second insulating layer 120A, and the third conductive layer is etched to form the compensation conductive line 70.

As shown in FIG. 10I, a third insulating layer 130A is formed on the compensation conductive line 70 and the second insulating layer 120A.

As illustrated in FIG. 10J, a fourth conductive layer is deposited on the third insulating layer 130A, and the fourth conductive layer is etched to form the mirror driving conductive line 60.

Hereinafter, the deposition process of the first conductive layer to the fourth conductive layer and the formation process of the first insulation layer to the third insulation layer as shown in FIGS. 10C to 10J will be described in detail.

As each conductive layer to be deposited, an aluminum layer is used. As the aluminum layer is deposited and photo-etched, a step of several μm is generated, and when the aluminum layer is deposited, the step for overcoming the driving current must be seamlessly achieved when the aluminum layer is to be overcome. In order to deposit a metal thin film while overcoming the step, it is generally relying on sputtering by argon plasma, but the deposition rate is very low, such as several kW / sec, which requires a lot of cost and time to deposit a metal film having a thickness of 1 to 2 μm. do. Therefore, a thermal evaporation process was used to replace this, but the tilted substrate was allowed to simultaneously rotate and revolve while the metal was deposited. The deposition rate is at least 20 kW / sec and the deposition thickness is 2 μm. As a result of the deposition, aluminum is uniformly deposited on the front and side surfaces of the fine step, and then the conductive wire fabricated through the photolithography process is successfully implemented.

 The conductive lines are implemented through a photolithography process on the deposited aluminum layer. Since the first conductive layer 3A is aluminum deposited on a flat substrate having no step difference, the photoconductive process may be performed by applying the thin film photosensitive agent AZ5214.

  The AZ5214 photoresist is developed in a developer and then heat treated in an oven at 110 ° C. for 20 minutes. In this process, the photoresist reflows and the adhesion increases as residual solvent is removed. This increase in adhesion is very effective in minimizing the lateral etching in the aluminum wet etching to prevent the line width of the conductive line from decreasing.

  A mixture of phosphoric acid, nitric acid, acetic acid and deionized water is used for aluminum wet etching. The mixing ratio is 16: 1: 1: 2, and the etching rate is 500Å / min when the etching is performed at room temperature. Generally, wet etching of aluminum is performed by heating to 40 ° C., but when heated, lateral etching is very severe as the etching rate increases. This is a phenomenon in which the etching liquid penetrates into the interface between the substrate and the photosensitive agent as the temperature increases, the substrate adhesion of the photosensitive agent as the etching mask becomes weak. Therefore, in order to minimize the lateral etching to realize the most accurate line width, room temperature etching and heat treatment before etching are required.

  From the second conductive layer, a photoresist was applied by applying a thick film photosensitive agent having a thickness of 16 μm in order to overcome the step difference. In order to overcome the above-described step, the photoresist is applied to a thickness that is several times the step to completely flatten the step.

After the photographing process is completed, the photoresist is subjected to heat treatment. Since the AZ4620 photoresist is reflowed at a temperature of 100 ° C. or higher, heat treatment in an oven at 110 ° C. for 20 minutes can provide very good substrate adhesion. In addition, since the minute gap between the stepped portion and the photoresist is completely filled through the reflow process, disconnection of the conductive line due to penetration of the aluminum etchant may be prevented.

An insulating layer is required between the layers of each aluminum, and PECVD SiO ₂ and BCB are used as insulating materials. Since there are a total of four aluminum layers, three insulation layers are required. PECVD SiO ₂ is deposited to a thickness of 1 μm between the first and second conductive layers and between the second and third conductive layers to form a first insulating layer 110A and a second insulating layer 120A, respectively.

 BCB is applied between the third and fourth conductive layers to form a third insulating layer 130A. All the conductive lines are located 50 m inward from the edges of the mirror 30 and the rotating frame 20, and the width of the conductive lines is 75 m.

  The mechanical properties of BCB (Benzocyclobutene, CYCLOTENE, Dow Chemical Company) are similar to those of polyimide commonly used in MEMS, but are easy to flatten on the substrate after application. This is because the polyimide begins to cure immediately after application, but BCB maintains its initial viscosity until heat treatment. CYCLOTENE is a negative photosensitive BCB that can be directly patterned through the photo process, but in the thick film process with a thickness of 40㎛, it is difficult to realize accurate dimensions because BCB's UV transmittance is poor. In addition, since the negative photosensitive polymer is generally exposed to UV light and generates a very strong stress during polymerization, processing by heat treatment and dry etching is advantageous in terms of mechanical properties. Therefore, dry etching of BCB is used to implement the designed pattern.

  BCB should use AP3000 (DOW Chemical Company), which is an adhesion improving agent because of poor substrate adhesion. Using a spinner, the AP3000 is first coated on the substrate, and BCB is applied thereto, and then left at room temperature for at least 20 minutes. In this process, all the bubbles inside the coated film come out, and all the steps generated during the application are flattened. The heat treatment process proceeds with increasing temperature gradually. The glass temperature of the BCB is 350 ° C., and the state of the BCB used to make the spring of the two degree of freedom scanning mirror is not vitrified and thus shows the characteristics of a very flexible spring.

  The top layer aluminum photolithography process is performed on a layer of aluminum deposited thermally over the BCB thick film and used to make the mirror drive conductive line 60. An etching mask is required for dry etching of BCB. Instead of making a separate etching mask, a conductive line pattern of uppermost aluminum is made and then used as a BCB dry etching mask.

 Next, as shown in FIG. 10K, the rotation through hole 3a and the silicon layer exposing the periphery of the silicon layer are etched using the mirror drive conductive line 60 and the rotation frame drive conductive line 50 as a mask. The mirror through hole 3b exposing the center part is formed again.

Next, as shown in FIG. 3C, the silicon layer 1 is etched using the rotating frame mask 3d and the mirror mask 3e as a mask to fix the fixed frame 10, the rotating frame 20, and the mirror 30. ) And a rotating frame spring 80 connecting the fixed frame 10 and the rotating frame 20, and a mirror spring 90 connecting the rotating frame 20 and the mirror 30.

 The process shown in FIGS. 10K and 3C is described in detail below. After the rotation frame driving conductive line 50, the mirror driving conductive line 60, and the compensation conductive line 70 are manufactured, the silicon layer 1 is released to form the rotation frame 20 and the mirror 30. The release of the silicon layer 1 refers to the formation of an empty space by causing undercut to occur during etching of the silicon layer. Upon release of the silicon layer, silicon isotropic dry etching was used to remove all of the silicon below the rotating frame spring 80 and the mirror spring 90. In the silicon dry etching process, the silicon is intentionally laterally removed to remove the spring-forming polymer and the silicon under the aluminum conductive line.

 Since the two-degree-of-freedom scanning mirror of the present invention is a multilayer structure having a first aluminum layer and three layers of aluminum conductive wires used as an etch mask of the mirror 30 and the rotating frame 20, the PECVD oxide film and the BCB are interposed between the aluminum layers. Was coated and insulated. Therefore, aluminum deposition, photolithography process and insulating film deposition process is repeated. When the insulating process and the driving conductive lines on the mirror 30 and the rotating frame 20 are completed, the unnecessary PECVD oxide (insulating layer) and BCB in the portion without the conductive lines are dry-etched and removed. This is to prevent the mirror 30 and the rotating frame 20 from twisting due to the stress of the PECVD oxide film and the BCB. In particular, the stress generated after the heat treatment of the BCB is very strong, the distortion of the mirror 30 and the rotating frame 20 and damage to the conductive wire structure fabricated thereon must be removed. The mirror 30 and the rotating frame 20 are released before wafer dicing using isotropic silicon dry etching, and a method of temporarily fixing and using a photosensitive agent to perform the wafer cutting process while protecting the released structure. Take it.

A cross-sectional view of a two degree of freedom scanning mirror according to a second embodiment of the present invention is shown in FIGS. 11A-11D. Here, the same reference numerals as in the above-described drawings indicate the same members having the same function.

A schematic diagram of the two degree of freedom scanning mirror according to the second embodiment is the same as that of FIG. 1 and will be described with reference to FIG. 1.

1, 11A to 11D, the two-degrees of freedom scanning mirror according to the second embodiment of the present invention is a rotating frame which is disposed inside the fixed frame 10 and the fixed frame 10 at predetermined intervals. 20 and the mirror 30 disposed inside the spaced apart from the rotation frame 20 by a predetermined interval. Then, the permanent magnet 40 is disposed on the rotating frame 20 and the mirror 30 spaced apart from the rotating frame 20 and the mirror 30 by a predetermined interval.

A portion of the upper surface of the rotating frame 20 is formed with a rotating frame driving conductive line 50, which generates a first rotational force in the rotating frame 20. In addition, a mirror driving conductive line 60 is formed on a part of the upper surface of the rotating frame 20 and the mirror 30, which generates a second rotational force on the mirror 30. The compensation conductive line 70 is formed to correspond to the mirror driving conductive line 60 formed on the rotation frame 20. It is formed below the outline of the mirror drive conductive line 60 formed in the rotating frame 20.

The fixed frame 10 and the rotating frame 20 are connected by the rotating frame spring 80, and the rotating frame 20 and the mirror 30 are connected by the mirror spring 90. The central axis of the rotating frame spring 80 is the first rotation axis to rotate the rotating frame 20, the central axis of the mirror spring 90 is the second rotation axis to rotate the mirror 30.

Unlike the first embodiment, the second embodiment of the present invention is used as a high speed mirror. This is because the rotating frame spring 80 and the mirror spring 90 of the second embodiment use silicon instead of BCB as the third insulating layer.

The high speed mirror is manufactured with a high resonant frequency as a priority, and the silicon of the same material as that of the mirror 30 and the rotating frame 20 is manufactured together with a spring. Such a high speed mirror has a resonant frequency of 1 kHz or more and is not affected by disturbance.

12 and 13 show the shapes of the rotating frame spring pair of the multilayer structure and the mirror spring pair of the multilayer structure.

12 is a schematic view of a rotating frame spring 80 connecting the rotating frame 20 to the stationary frame 10. Several layers of conductive layers sandwiched between insulating films are made equal to a pair of springs, and on an electrical circuit they have a parallel circuit structure.

The rotating frame spring 80 includes the first insulating layer 110, the rotating frame driving conductive line part 50a, the second insulating layer 120, the compensation conductive line part 70a, the third insulating layer 130, and the mirror. The drive conductive line part 60a is formed in order from the bottom. Since the rotation frame spring 80 connects the fixed frame 10 and the rotation frame 20 spaced apart from each other by a predetermined interval, an empty space is formed at the bottom of the rotation frame spring 80. That is, one end of the rotating frame spring 80 is connected to the fixed frame 10 and the other end of the rotating frame spring 80 is connected to the rotating frame 20, the fixed frame 10 and the rotating frame 20 An intermediate portion of the rotating frame spring 80 is formed in the first through hole 3a of the liver.

As shown in FIGS. 11A to 11D, the first insulating layer 110 is formed on the top surface of the fixed frame mask 3c, the rotation frame mask 3d, and the mirror mask 3e. The fixed frame mask 3c, the rotating frame mask 3d and the mirror mask 3e are aluminum layers used as masks to form the rotating frame 20 and the mirror 30, and the fixed frame 10, the rotating frame It is formed in the upper surface of the 20 and the mirror 30. The first insulating layer 110 may be formed of an oxide film (SiO ₂ ). The first insulating layer 110 is not formed in the middle of the rotating frame spring 80 formed in the first through hole 3a between the fixed frame 10 and the rotating frame 20.

The rotation frame driving conductive line part 50a is formed on the first insulating layer 110. The rotating frame driving conductive line part 50a is a part connecting the rotating frame 20 and the fixed frame 10 as part of the rotating frame driving conductive line 50.

The second insulating layer 120 is formed on the rotation frame driving conductive line part 50a. The second insulating layer 120 is preferably formed of an oxide film (SiO ₂ ).

The compensation conductive line part 70a is formed on the second insulating layer 120. The compensation conductive line part 70a is a part connecting the rotating frame 20 and the fixed frame 10 as part of the compensation conductive line 70.

The third insulating layer 130 is formed on the compensation conductive line part 70a. The third insulating layer 130 is preferably formed of a silicon oxide film (SiO ₂ ). In the second embodiment of the present invention, since the insulating layer is formed of the silicon oxide film, it has very strong characteristics against mechanical fatigue, and the life of the device is longer because the memory effect of the spring is less.

The mirror driving conductive line part 60a is formed on the third insulating layer 130. The mirror drive conductive line part 60a is a part which connects the rotation frame 20 and the fixed frame 10 as a part of the mirror drive conductive line 60.

As shown in Fig. 12, the pairs of conductive layers of the same layer in the pair of springs are configured to flow current in the same direction. However, the current direction between the upper and lower conductive layers does not always coincide because the rotation frame driving current 5, the compensation current 7, and the mirror driving current 6 are applied at independent frequencies.

Lateral etching occurs during silicon dry etching through the intervals 85 between the pair of rotating frame springs 80 to shorten the process time and simultaneously reduce the thickness of the rotating mirror 30 and the rotating frame 20. The advantage is that it can be reduced.

13 shows a pair structure of mirror springs connecting the mirror 30 to the rotating frame 20. The mirror spring 90 has a single conductive layer thereon. Since the first to third insulating layers 110, 120, and 130 are deposited together in an insulating process between the conductive line layers on the rotating frame spring 80, a thick insulating layer is formed.

 As for the mirror spring 90, the 1st insulating layer 110, the 2nd insulating layer 120, the 3rd insulating layer 130, and the mirror drive conductive line part 60b are formed in order from the bottom. Since the mirror spring 90 connects the rotating frame 20 and the mirror 30 spaced apart from each other by a predetermined interval, the bottom surface of the mirror spring 90 has an empty space. That is, one end of the mirror spring 90 is connected to the rotating frame 20, the other end of the mirror spring 90 is connected to the mirror 30, and a second penetration between the rotating frame 20 and the mirror 30 is performed. The middle part of the mirror spring 90 is formed in the sphere 3b.

The first insulating layer 110 is formed on the upper surface of the fixed frame mask 3c, the rotating frame mask 3d, and the mirror mask 3e. The fixed frame mask 3c, the rotating frame mask 3d, and the mirror mask 3e are aluminum layers used as masks to form the rotating frame 20 and the mirror 30, and the fixed frame 10, the rotating frame It is formed in the upper surface of the 20 and the mirror 30. The first insulating layer 110 may be formed of an oxide film (SiO ₂ ).

The second insulating layer 120 is formed on the first insulating layer 110. The second insulating layer 120 is preferably formed of an oxide film (SiO ₂ ). The first insulating layer 110 and the second insulating layer are not formed in the middle portion of the mirror spring 90 formed in the second through hole 3b between the rotating frame 20 and the mirror 30.

The third insulating layer 130 is formed on the second insulating layer 120. The third insulating layer 130 is preferably formed of a silicon oxide film (SiO ₂ ). In the second embodiment of the present invention, since the insulating layer is formed of the silicon oxide film, it has very strong characteristics against mechanical fatigue, and the life of the device is longer because the memory effect of the spring is less.

The mirror driving conductive line part 60b is formed on the third insulating layer 130. The mirror drive conductive line part 60b is a part which connects the rotating frame 20 and the mirror 30 as a part of the mirror drive conductive line 60.

An input current and an output current 6 for driving the mirror flow through the pair of mirror drive conductive line portions 60b flowing over the mirror spring 90, and the current direction always flows in the opposite direction. Therefore, the insulation between these two conductive wires is very important. In addition, the spacing 95 between the pair of mirror springs allows the lateral etching in the silicon isotropic dry etching to proceed quickly so that the structure is undercut.

A method of manufacturing a two degree of freedom scanning mirror according to a second embodiment of the present invention is shown in Figs. 14A to 14K.

 As shown in FIG. 14A, a silicon on glass (SOG) in which silicon 1 and glass 100 are bonded is used to manufacture a two degree of freedom scanning mirror according to the first embodiment of the present invention. This is because a large selectivity can be obtained in the process of processing both sides of the substrate. The thickness of the silicon 1 of the second embodiment is equal to the thickness of the rotating frame spring 80 and the mirror spring 90. Thus, the thickness of the silicon 1 in the SOG of the second embodiment is thin so as to meet the required spring constant.

Next, as shown in FIG. 14B, a glass wet etching process is performed to form the silicon support 100.

Next, as shown in FIG. 14C, a first conductive layer 3A is deposited on the silicon layer 1.

As shown in FIG. 14D, the first conductive layer 3A is etched to have the rotation through hole 3a exposing the periphery of the silicon layer 1 to fix the fixed frame etching mask 3c and the rotation frame etching. The mask 3d is formed, and at the same time, the first conductive layer 3A is etched to have the mirror through hole 3b exposing the center portion of the silicon layer 1 to form the mirror etch mask 3e.

As shown in FIG. 14E, the first insulating layer 110A is formed on the fixed frame etching mask 3c, the rotating frame etching mask 3d, and the mirror etching mask 3e.

As illustrated in FIG. 14F, a second conductive layer is deposited on the first insulating layer 110A, and the second conductive layer is etched to form the rotation frame driving conductive line 50.

As illustrated in FIG. 14G, a second insulating layer 120A is formed on the rotation frame driving conductive line 50 and the first insulating layer 110A.

As shown in FIG. 14H, a third conductive layer is deposited on the second insulating layer 120A, and the third conductive layer is etched to form the compensation conductive line 70.

14I, a third insulating layer 130A is formed on the compensation conductive line 70 and the second insulating layer 120A. As the third insulating layer 130A, a silicon oxide film SiO ₂ is preferable.

As illustrated in FIG. 14J, a fourth conductive layer is deposited on the third insulating layer 130A, and the fourth conductive layer is etched to form the mirror driving conductive line 60.

Next, as shown in FIG. 14K, the rotation through hole 3a and the silicon layer exposing the periphery of the silicon layer are etched by using the mirror drive conductive line 60 and the rotation frame drive conductive line 50 as a mask. The mirror through hole 3b exposing the center part is formed again.

Next, as shown in FIG. 11C, the silicon layer 1 is etched using the rotating frame mask 3d and the mirror mask 3e as a mask to fix the fixed frame 10, the rotating frame 20, and the mirror 30. ) And a rotating frame spring 80 connecting the fixed frame 10 and the rotating frame 20, and a mirror spring 90 connecting the rotating frame 20 and the mirror 30.

As described above, the manufacturing method of the second embodiment which is a high speed mirror coincides with the first embodiment where the majority of the process is a low speed mirror, but the fixed frame 10 by anisotropic dry etching of the silicon 1 in the silicon etching process, Forming the rotating frame 20 and the mirror 30 is different. That is, in the first embodiment, the third insulating layer 130 is coated using BCB. In the second embodiment, all the insulating layers including the third insulating layer 130 are PECVD oxide films. The rotation frame spring 80 and the mirror spring 90 of the embodiment occupy most of the thickness of BCB, and for this purpose, silicon under the rotation frame spring 80 and the mirror spring 90 through isotropic silicon dry etching during silicon etching. All also removed. However, since the rotating frame spring 80 and the mirror spring 90 of the second embodiment are silicon 1, the anisotropic silicon dry etching process is performed in the final etching process. Thus, the fixed frame 10, the rotating frame 20 and the mirror 30 are all connected by the silicon 1.

This first and second embodiments of the present invention represent a low speed mirror and a high speed mirror, respectively.

The low-speed mirror has a large rotation angle, but the high-speed mirror adopts silicon spring, which is very strong against mechanical fatigue, and the device's life is longer because the spring's memory effect is less. Since the magnitude of the resonant frequency is proportional to the strength of the spring and the magnitude of the rotation angle is inversely proportional, it is not easy to fabricate a device having both the advantages of the low speed mirror and the high speed mirror by one design specification.

  When manufacturing the low speed mirror and the high speed mirror by the same process with the same spring material, desired specifications can be obtained by changing the size of the mirror plate, the length and width of the spring, and the like. However, in this case, the photo masks used in the manufacturing process must be manufactured differently and modeled and analyzed separately. In order to avoid the cost increase and the difficulty of comparing the performance, the same photo mask is employed in the present invention, but the low speed mirror and the high speed mirror are manufactured by varying the thickness of the spring material and the thickness of the rotating body. The low-speed mirror used BCB (benzocyclobutanes) as a spring material, and the high-speed mirror employs a rotating frame 20 and silicon used as a spring material.

Although the present invention has been described with reference to one embodiment shown in the accompanying drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Could be. Accordingly, the true scope of protection of the invention should be defined only by the appended claims.

The two degree of freedom scanning mirror according to the present invention minimizes the interference between the rotational axes by using a compensation conductive line.

In addition, the two-degree-of-freedom scanning mirror of the present invention implements the rotation of the mirror about two rotation axes by applying an external magnetic field with only a single permanent magnet, and can be miniaturized because independent control of each rotation axis is possible.

In addition, since it is driven by the electromagnetic force driving method, low-power driving is possible, and it is easy to remove the disturbance by the high driving frequency, and thus it is possible to produce at low cost.

In addition, the manufacturing method of the two-degree-of-freedom scanning mirror according to the present invention can overcome the step by the aluminum thermal evaporation method for rotating and revolving the inclined substrate and the photolithography process using a thick film photosensitive agent to produce a conductive line that is not broken.

In addition, according to the manufacturing method of the two-degree-of-freedom scanning mirror according to the present invention, the polymer spring, which is a low speed mirror, and the silicon spring, which is a high speed mirror, can be manufactured using the same process.

In addition, BCB was processed at a temperature below the vitrification temperature to ensure flexibility. In addition, planarization is very excellent when BCB is applied as the uppermost insulating film, so that the conductive lines of three layers are well formed to overcome the step difference.

1 is a schematic view showing a two degree of freedom scanning mirror according to a first embodiment of the present invention,

2 is an exploded view of a permanent magnet, a mirror drive conductive line, a compensation conductive line, a rotating frame drive conductive line, a mirror, a rotating frame, and a fixed frame,

3A to 3D are cross-sectional views taken along the lines II ′, II-II ′, III-III ′, and IV-IV ′ of FIG. 1, respectively.

4 is a plan view of a fixed frame, a rotating frame and a mirror,

FIG. 5 is a diagram illustrating directions of a rotating frame driving conductive line and a mirror driving conductive line, a rotating frame driving current, and a mirror driving current formed on the upper surface of the rotating frame and the mirror,

6 is a diagram illustrating a direction of a compensation conductive line and a compensation current formed on an upper surface of a rotating frame;

FIG. 7 is a diagram illustrating a rotating frame spring pair having a multilayer structure in which the first insulating layer under the rotating frame driving conductive line is not etched according to the first embodiment of the present invention.

FIG. 8 is a diagram illustrating a mirror spring pair having a multilayer structure in which the first and second insulating layers under the mirror driving conductive line according to the first embodiment of the present invention are not etched.

9 is a view illustrating a connection pad, a rotation frame driving current input / output pad, a mirror driving current input / output pad, and a connection pad formed on a fixed frame;

10A to 10K are diagrams sequentially illustrating a method of manufacturing a two degree of freedom scanning mirror according to the first embodiment of the present invention.

11A to 11D are cross-sectional views of the two-degrees of freedom scanning mirror according to the second embodiment of the present invention, respectively, in FIGS. 1-I ', II-II', III-III ', and IV-IV, respectively. 'Is a cross-sectional view cut along

12 is a view illustrating a pair of rotating frame springs having a multi-layer structure in which the first insulating layer under the rotating frame driving conductive line is not etched according to the second embodiment of the present invention.

FIG. 13 is a diagram illustrating a mirror spring pair having a multilayer structure in which first and second insulating layers under the mirror driving conductive line according to the second embodiment of the present invention are not etched.

14A to 14K are diagrams sequentially showing a method of manufacturing a two degree of freedom scanning mirror according to a second embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

10; Fixed frame 20; Rotating frame

30; Mirror 40; Permanent magnet

50; Rotating frame drive conductive line 60; Mirror drive conductor

70; Compensation conductor 80; Rotating frame spring

90; Mirror spring 110; First insulating layer

120; Second insulating layer 130; Third insulating layer

Claims (27)

Fixed frame; A rotating frame spaced apart from the fixed frame at a predetermined interval and rotated by a predetermined angle about a first rotation axis; A mirror disposed at an inner side and spaced apart from the rotating frame by a predetermined angle, the mirror rotating at a predetermined angle about a second rotational axis perpendicular to the first rotational axis; A permanent magnet disposed under the rotating frame and the mirror; A rotation frame driving conductive line formed on the rotation frame and generating a first rotation force to the rotation frame; A mirror driving conductive line formed on the rotating frame and the mirror and generating a second rotational force to the mirror; A compensation conductive line insulated from the mirror driving conductive line at a position corresponding to the mirror driving conductive line formed in the rotation frame; A rotating frame spring connecting the fixed frame and the rotating frame; Mirror spring connecting the rotating frame and the mirror 2 degrees of freedom scanning mirror comprising a. In claim 1, And a two-degree-of-freedom scanning mirror in which the current flows in a direction opposite to a current flowing in the mirror driving conductive line formed in the rotating frame. In claim 1, The rotation frame spring is a portion in which a part of the rotation frame driving conductive line, the compensation conductive line, and the mirror driving conductive line overlaps, and includes two degrees of freedom scanning including a rotation frame driving conductive line part, a compensation conductive line part, and a mirror driving conductive line part. mirror. In claim 3, And a first insulating layer is formed on a portion of a bottom surface of the rotating frame driving conductive line portion of the rotating frame spring. In claim 3, And a second insulating layer between the rotation frame driving conductive line portion and the compensation conductive line portion, and a third insulating layer between the compensation conductive line portion and the mirror driving conductive line portion. In claim 2, And the mirror spring includes a mirror drive conductive line portion, wherein the mirror drive conductive line is a portion connecting the rotating frame and the mirror. In claim 6, And a first, second and third insulating layers are continuously formed on a portion of the bottom surface of the mirror driving conductive line portion of the mirror spring. In any one of claims 4, 5 or 7, And the first and second insulating layers are oxide films. In claim 8, And said third insulating layer is a polymer. In claim 8, And the third insulating layer is a silicon oxide film. In claim 1, And the rotation frame springs are a pair of rotation frame drive conductive line portions, a compensation conductive line portion, and a mirror drive conductive line denying two degrees of freedom scanning mirror spaced apart from each other by a predetermined distance. In claim 1, And said mirror spring is a pair of mirror drive conductive line denying two degrees of freedom scanning mirrors spaced apart from each other by a predetermined distance. In claim 1, And the mirror driving conductive line and the compensation conductive line are connected through a connection pad formed on the fixed frame. In claim 1, And a rotating frame driving current input pad and an output pad connected to the rotating frame driving conductive line on the fixed frame. In claim 1, And a mirror driving current input pad and an output pad connected to the mirror driving conductive line on the fixed frame. In claim 1, And said fixed frame, rotating frame and mirror are silicon. In claim 1, And the mirror drive conductive line, the rotation frame drive conductive line, and the compensation conductive line are aluminum. In claim 1, And a first conductive layer formed on upper surfaces of the fixed frame, the rotating frame, and the mirror. Forming a silicon layer on the substrate; Depositing a first conductive layer on the silicon layer, and etching the first conductive layer to have a rotation through hole exposing a periphery of the silicon layer to form a rotation frame etching mask, and simultaneously the first conductive layer is Etching to have a mirror through hole exposing a center portion of the silicon layer to form a mirror etching mask; Forming a first insulating layer on the rotating frame etching mask and the mirror etching mask; Depositing a second conductive layer on the first insulating layer and etching the second conductive layer to form a rotation frame driving conductive line; Forming a second insulating layer on the rotating frame driving conductive line and the first insulating layer; Depositing a third conductive layer on the second insulating layer and etching the third conductive layer to form a compensation conductive line; Forming a third insulating layer on the compensation conductive line and the second insulating layer; Depositing a fourth conductive layer on the third insulating layer and etching the fourth conductive layer to form a mirror driving conductive line; Etching the mirror driving conductive line, the rotating frame driving conductive line as a mask to form a rotation through hole exposing a periphery of the silicon layer, and a mirror through hole exposing a center portion of the silicon layer; The silicon layer is etched using the rotating frame mask and the mirror mask as a mask to form a fixed frame, a rotating frame and a mirror, and a rotating frame spring connecting the fixed frame and the rotating frame, and a mirror connecting the rotating frame and the mirror. Forming spring Method of manufacturing a two degree of freedom scanning mirror comprising a. The method of claim 19, And the first to fourth conductive layers are made of aluminum. The method of claim 20, And the first insulating layer and the second insulating layer are formed of an oxide film. The method of claim 21, And the third insulating layer is formed of a polymer. The method of claim 22, And planarizing the third insulating layer after forming the third insulating layer. The method of claim 21, And the third insulating layer is formed of a silicon oxide film. The method of claim 21, Forming a support of the substrate by etching the central portion of the substrate after forming the silicon layer. The method of claim 22, The etching of the silicon layer may include isotropic dry etching. The method of claim 24, The etching of the silicon layer may include anisotropic dry etching.