KR0150547B1 - Optical path control apparatus and fabricating method thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical path adjusting device and a manufacturing method thereof, and more particularly to an uppermost layer of an actuated mirror array (hereinafter abbreviated as AMA) as an optical path adjusting device employed in a projection image display device. The present invention relates to an optical path control device having a dielectric thin film coating process to increase reflectance and to serve as a protective film, and to a method of manufacturing the same, wherein a pad (not shown) is embedded in a matrix and electrically connected to the transistor on top (Not shown), a membrane 57 stacked with a predetermined air gap 50 on the driving substrate 51, and grooves are formed in the membrane 57. A conductive plug 59 connected to a pad on the driving substrate 51, a deformable portion 63 connected to the plug 59 and stacked on the membrane 57; An upper electrode 65 stacked on the deformable portion 63 and a lower dielectric thin film 66 and an upper layer stacked on the upper electrode 65 to protect the upper electrode 65 and increase reflectance. Including the dielectric thin film 67, according to the present invention protects the thin-film mirror and at the same time obtains the effect of increasing the reflectance, the present invention is an active mirror of BaTiO ₃ system, PAZT optical application mirror, SiO Of course, it can be widely applied to _two actuated mirrors and other optical application actuated mirrors.

Description

Optical path control device and manufacturing method

1 (a) to (d) is a cross-sectional view for explaining a manufacturing method of the optical path control apparatus according to the prior art.

2 is a cross-sectional view showing an optical path control apparatus according to the present invention.

3 is a graph showing reflectance according to wavelength.

* Explanation of symbols for main parts of the drawings

11, 51: driving substrate 15: sacrificial film

17, 57: membrane 19, 59: plug

21, 61: lower electrode 23, 63: deformation part

25, 65: upper electrode 26: protective film

29, 59: actuator 66: lower dielectric thin film

67: upper dielectric thin film

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical path adjusting device and a manufacturing method thereof, and more particularly, to an uppermost layer of an actuated mirror array (hereinafter, abbreviated as AMA) as an optical path adjusting device employed in a projection image labeling device. The present invention relates to an optical path adjusting device having a dielectric film coating treatment to increase a reflectance thereon and act as a protective film, and a method of manufacturing the same.

In general, conventional image display apparatuses are classified into a direct display type represented by a CRT device and a projection display device represented by an LCD device. Among them, the CRT device, which is a direct view display device, forms an RGB fluorescent point on a fluorescent panel. When the electron beam is focused on the RGB fluorescent point, the fluorescence point is emitted to enable the display of a color image. However, in such a CRT apparatus, the RGB fluorescent point should be formed for one pixel, while the patterning process of black stripe is performed. Since it is necessary, not only the size is limited, but also the manufacturing process is complicated, which increases the manufacturing cost. On the other hand, in the LCD device which is a projection display device, a voltage corresponding to an image signal is applied to the liquid crystal driving voltage from a uniform arrangement of liquid crystals, so that the display of the target image is performed by adjusting the alignment direction of the liquid crystals by the polarizing plate. Although thinning is possible, such LCD device has the disadvantage that the light loss is increased by the polarizing plate for adjusting the amount of light emitted relative to the total amount of incident light.

Accordingly, a projection image display device using AMA was developed by Aura of the United States. Image display apparatuses using AMA are classified into one-dimensional AMA and two-dimensional AMA. One-dimensional AMAs are arranged in an M × 1 array. Therefore, the projection type image display apparatus using the one-dimensional AMA pre-scans the M × 1 beams using the scanning mirror, and the projection image display apparatus using the two-dimensional AMA projects the M × N luminous fluxes to produce an array of M × N pixels. It will have a shape with.

1 is a cross-sectional view of the manufacturing process for explaining the manufacturing method of the optical path control device consisting of the AMA.

That is, in the manufacturing method of the optical path control apparatus according to the prior art, first, a transistor (not shown) is built in a matrix form and has a pad (not shown) having a pad (not shown) electrically connected to the transistor thereon. A sacrificial film 15 is formed on the surface with a thickness of about 1 to 2 μm. Here, the sacrificial film 15 is preferably formed of a metal material such as Mo, Cu, Fe, Ni, Al, or PSG (Phospho-Silicate Glass) or ZnO. When forming the metal material, sputtering is performed. By the method, PSG is formed by spin coating or chemical vapor deposition (hereinafter, abbreviated as CVD), and ZnO is formed by sputtering or CVD. Then, the sacrificial film 15 of the predetermined portion is removed by a conventional photomasking (also called photolithography) method to expose the pad (not shown) and the driving substrate 11 around it. Thereafter, silicides such as silicon oxide (SiO ₂ ) or silicon nitride (Si ₃ N ₄ ) are deposited on the entire surface of the above-described structure to a thickness of about 0.7 to 2 μm by sputtering or CVD to form a membrane 17. . Subsequently, the membrane 17 on the pad (not shown) is removed to form a groove so that the pad is exposed, and a plug 19 electrically connected to the pad is formed by filling a conductive metal in the groove. [See FIG. 1 (a)].

Subsequently, platinum (Pt) or platinum / titanium (Pt / Ti) or the like is applied to the entire surface of the membrane 17 to a thickness of about 500 to 2000A by vacuum deposition or sputtering, and then the sacrificial film 15 ) And the remaining portion except for the predetermined portion including the overlapped portion to form the lower electrode 21. Subsequently, pressure ceramics or electro-distortion ceramics are applied to the entire surface of the structure described above by a thickness of about 0.7 to 2 μm by the Sol-Gel method, the sputtering method, or the CVD method, and then sintered to form a phase transition. 23). Subsequently, a thickness of about 500 to 2000 A may be obtained by sputtering or vacuum depositing a material having good reflection and electrical properties such as platinum / titanium (Pt / Ti) or aluminum / titanium (Al / Ti) on the deformation part 23. The upper electrode 25 having this is formed. Next, the upper electrode 25 and the deformable portion 23 are patterned by using a conventional photomasking method, and the pixels are separated to form an actuator 29 (see FIG. 1 (b)).

Next, a protective film 26 made of silicon oxide or silicon nitride is applied to the entire surface of the structure described above, and then the protective film 26 is patterned to expose the sacrificial film 15 (FIG. 1 (c)). Reference].

Subsequently, the sacrificial film 15 is removed by a wet etching method using a solution such as HF or BOE. In this case, when the sacrificial wafer 15 is made of PSG, the sacrificial film 15 is formed into an HF solution or a BOG solution as an etching solution. After immersion for a predetermined time, the sacrificial film 15 is etched away to form an air gap, and then rinsed with unionized pure water (DI-WATER) or methanol. The rinse liquid is dried to complete the manufacturing process of the optical path control device including the actuator 29 (see FIG. 1 (d)).

For reference, the reflectance (%) according to the wavelength of aluminum (Al) and platinum (Pt), which are main materials of the upper electrode 25, which is the uppermost layer of the optical path control value, is as shown in Table 1 below. Please note that the reflectance may be slightly different depending on the conditions.

However, the optical path control device according to the conventional method for manufacturing the optical path control device described with reference to FIGS. 1A to 1D has a top layer, that is, platinum / titanium (Pt / Ti) or aluminum / titanium. Since the upper electrode layer made of a material such as (Al / Ti) is exposed to the outside, there is a risk of damage due to physical and chemical influences from the outside, and in the case of platinum, the reflectance is lower than that of aluminum. Able to know.

Accordingly, the present invention has been made in view of the above, and an object thereof is to provide a dielectric thin film on an uppermost layer of an actuated mirror array, that is, an upper electrode, as an optical path adjusting device employed in a projection image display device. It is to provide an optical path control device and a method of manufacturing the same to increase the reflectance and to act as a protective film at the same time.

According to a preferred embodiment of the optical path control apparatus according to the present invention for achieving the above object, a drive substrate having a pad in which the transistor is embedded in a matrix form and electrically connected to the transistor thereon, and a predetermined shape on the drive substrate. A membrane layer stacked with an air gap, a conductive plug forming a recess in the membrane layer and connected to a pad on the driving substrate, a lower electrode layer stacked on the membrane layer to be connected to the plug, and the lower electrode layer And a dielectric layer layer laminated on the upper portion of the deformed portion layer, an upper electrode layer stacked on the upper portion of the deformable portion layer, and laminated on the upper electrode layer to protect the upper electrode layer and increase the reflectance.

The dielectric thin film layer includes an upper dielectric thin film layer having a relatively high refractive index and a lower dielectric thin film layer having a low refractive index.

In addition, according to a preferred embodiment of the optical path control device manufacturing method according to the present invention for achieving the above object, the transistor is embedded in a matrix form and the pad is electrically connected to the transistor on the surface of the drive substrate A first step of forming a sacrificial layer so as not to contact the pad, a second step of depositing a membrane on the sacrificial layer, and forming a groove to expose the pad to a predetermined portion of the membrane; A third step of forming a plug to be in contact with the plug and applying a lower electrode on the membrane to be in contact with the plug; a fourth step of depositing a deformation part on a surface of the lower electrode and depositing an upper electrode on the deformation part; Deposited by depositing a lower dielectric thin film having a relatively high refractive index on top of the upper electrode A fifth process of coating and depositing an upper dielectric thin film having a relatively low refractive index on the lower dielectric thin film, depositing a protective film on the entire surface, and patterning the protective film and the membrane to expose the sacrificial film. And a seventh step of separating the sacrificial film and then rinsing the entire sacrificial film and then drying the rinse liquid.

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to the optical path control apparatus and its manufacturing method according to the present invention.

2 is a cross-sectional view showing an optical path control apparatus according to the present invention, wherein a driving substrate 51 having a transistor (not shown) embedded in a matrix form and having a pad (not shown) electrically connected to the transistor thereon. And a membrane 57 stacked with the air gap 50 having a predetermined shape on the driving substrate 51 and a groove formed in the membrane 57 to be connected to a pad on the driving substrate 51. Plug 59, a lower electrode 61 connected to the plug 59 and stacked on the membrane 57, a deformable portion 63 stacked on the lower electrode 61, and An upper electrode 65 stacked on the deformable portion 63 and a lower dielectric thin film 66 and an upper dielectric stacked on the upper electrode 65 to protect the upper electrode 65 and increase reflectance. It is characterized by including a thin film (67).

The lower dielectric thin film 66 is formed of silicon oxide (SiO 2), which has a relatively low refractive index, and has a thickness of about 822 kPa. The upper dielectric thin film 67 has a relatively high refractive index. It is preferable to form titanium oxide (TiO) with a thickness of about 522 t. The reason is that aluminum and silicon oxide, which are the materials of the upper electrode, are used for the production of optical mirrors due to their strong adhesive strength. This is because it is also bonded to be used in the manufacture of optical filters to increase the film protection role and reflectance. Here, the refractive index of the silicon oxide (SiO) is 1.46 and the refractive index of titanium oxide (TiO) is 2.30.

The thickness of the lower dielectric thin film 6 and the upper dielectric thin film 67 is preferably set to a thickness with respect to the wavelength λ / 4 when the center wavelength is λ, which is determined by the following equation (1).

Accordingly, the coating thickness (d) of the lower dielectric thin film 66 made of silicon oxide having a refractive index (n) of 1.46 and the upper dielectric thin film 67 made of titanium oxide having a refractive index of (n) of 2.30 by applying the formula (1). It can be seen that the results are 822A and 522A, respectively.

3 is a graph showing reflectance according to wavelength.

Here, the curve a represents the reflectance of the upper electrode 65 made of aluminum (Al), which formed the uppermost layer in the conventional optical path control device. When the complex refractive index of aluminum is N = n-λk, the reflectance of aluminum is It is calculated | required by following formula (2).

For reference, the refractive index (n) and the absorption coefficient (k) of aluminum according to the wavelength are shown in Table 2 below.

The curve b of FIG. 3 obtains the maximum reflectance when the upper and lower dielectric thin films 67 and 66 are coated on the upper electrode 65 to a thickness of 822 and 522 각각, respectively. By showing the curve of the reflectance according to the wave by the calculation of, it can be seen that the reflectance is further improved by the coating of the dielectric thin film compared to the reflectance curve (a) of the aluminum. This applies even within the limit of 10 degrees of incidence, in case of vertical incidence.

R1 and R2 in the formulas (2) and (3): reflectance

N: complex refractive index of aluminum (Al)

n: refractive index of aluminum (Al)

k: absorption coefficient

nh: refractive index 2.30 of silicon oxide (SiO ₂ )

nL: refractive index of titanium oxide (TiO ₂ ) 1.46

*: Conjugate complex mark.

Next, the manufacturing method of the optical path control apparatus according to the present invention configured as shown in FIG. 2 will be described.

That is, the manufacturing method of the optical path control apparatus according to the present invention is the same as the conventional manufacturing method described with reference to FIGS. 1 (a) to 1 (c), except that the upper electrode is the top layer of the conventional optical path control apparatus. The only difference is that the dielectric film is coated on (65) to act as a protective film while increasing the reflectance.

That is, a sacrificial film (not shown) is embedded such that a transistor (not shown) is embedded in a matrix form and a pad (not shown) electrically connected to the transistor does not contact the pad on an upper portion of a driving substrate formed on a surface thereof. And a second step of forming a groove so that the pad is exposed to a predetermined portion of the membrane 57 and depositing the membrane 57 on the sacrificial layer. The third step of forming the plug 59 to contact the contact surface and apply the lower electrode 61 on the membrane 57 in contact with the plug 59, the deformable portion on the surface of the lower electrode 61 The fourth step of depositing the upper electrode 6 on the upper part of the deformable part 63 and coating the lower dielectric thin film 66 having a relatively high refractive index on the upper electrode 65. By depositing the lower dielectric foil A fifth process of coating and depositing an upper dielectric thin film 67 having a relatively low refractive index on the film 66; depositing a protective film 68 on the entire surface, and forming the protective film 68 and the membrane 57 ), And the sixth step of separating the actuator 69 by exposing the sacrificial film to expose the sacrificial film, and then the seventh step of rinsing the whole (rinse) and then drying the rinse liquid after etching the sacrificial film Is done.

According to the present invention described in detail as described above to obtain the effect of increasing the reflectance while protecting the thin film mirror portion, the present invention is the actuated mirror of BaTiO ₃ system, PLZT optical application mirror, SiO ₂ activated mirror and other optical application actuating Of course, it can be widely applied to the activated mirror.

Claims (6)

The transistor is stacked in a matrix form and has a driving substrate 51 having a pad electrically connected to the transistor on the top thereof, and a predetermined shape of air gap 50 on the driving substrate 51. And a conductive plug 59 having a groove formed in the membrane 57 and connected to a pad on the driving substrate 51, and a lower electrode connected to the plug 59 and stacked on the membrane 57. (61), the deformable portion (63) stacked on the lower electrode (61), the upper electrode (65) stacked on the upper portion of the deformable portion (63), and on the upper electrode (65). The optical path control apparatus, comprising a lower dielectric thin film (66) and an upper dielectric thin film (67) stacked to protect the upper electrode (65) and increase reflectance. The optical path control device as set forth in claim 1, wherein the lower dielectric thin film (66) is made of silicon oxide (SiO ₂ ) and has a thickness of about 800 kPa to 900 kPa. The optical path control device according to claim 1, wherein the material of the upper dielectric thin film is made of titanium oxide (TiO ₂ ) and the thickness thereof is about 500 kPa to 600 kPa. A first process of forming a sacrificial layer in which a transistor is embedded in a matrix form and a pad electrically connected to the transistor does not come into contact with the pad on a driving substrate formed on a surface thereof, and a mebrain is deposited on the sacrificial layer; A second step of forming a groove to expose the pad to a predetermined portion of the membrane, and a third step of forming a plug to contact the pad in the groove and applying a lower electrode to the plug on top of the membrane And depositing a deformation portion on a surface of the lower electrode and depositing an upper electrode on the upper portion of the lower electrode, coating and depositing a lower dielectric thin film having a relatively low refractive index on the upper electrode and depositing the lower dielectric foil. A fifth process of coating and depositing an upper dielectric thin film having a relatively high refractive index on the film; Forming a protective film on the entire surface and patterning the protective film and the membrane to expose the sacrificial film to separate the actuator; and after etching and removing the sacrificial film, the entire rinse solution is rinsed. The manufacturing method of the optical path control apparatus characterized by including the 7th process of drying. 5. The method of claim 4, wherein in the fifth step, the corning of the lower dielectric thin film is deposited using silicon oxide (SiO ₂ ) so as to have a thickness of about 800 kW to 900 kW. The method of claim 4, wherein the coating of the upper dielectric thin film in the fifth process is performed using titanium oxide (TiO ₂ ) so as to have a thickness of about 500 kPa to 600 kPa.