KR100633862B1 - Mems capable of etching sacrifice layer precisely and manufacturing method thereof - Google Patents

Abstract

A MEMS(Micro Structure Mechanical System) capable of precisely etching a sacrificial layer and its manufacturing method are provided to precisely control a lateral sacrificial layer by using sawtooth-shaped holes. A dielectric(320) is formed on a substrate(310). A sacrificial layer(330) is formed on the dielectric. A ribbon structure(340) is formed on the sacrificial layer. The ribbon structure is etched to form plural ribbons and sawtooth-shaped holes at both ends thereof. A piezoelectric body(350) is formed on the ribbon structure to drive the ribbons. The sawtooth shapes formed at both ends of the holes are formed between the piezoelectric bodies corresponding to different signals. The sacrificial layer is eliminated by using an etchant through the holes. The dielectric is SiO2 and the sacrificial layer is Si. The sawtooth shape is formed by plural grooves.

Description

MEMS structure capable of precise etching of sacrificial layer and manufacturing method thereof

1 is a cross-sectional view of a diffractive optical modulator using a sacrificial layer of a MEMS structure according to the prior art.

2 is a plan view of a diffractive optical modulator using a sacrificial layer of a MEMS structure according to the prior art.

3 is a perspective view of a diffractive optical modulator using a sacrificial layer according to a preferred embodiment of the present invention.

4 is a plan view of a diffractive optical modulator capable of precise etching of a sacrificial layer according to a first embodiment of the present invention.

5 is a plan view of a diffractive optical modulator capable of precise etching of a sacrificial layer according to a second preferred embodiment of the present invention.

6 is a manufacturing process diagram of the diffraction type optical modulator using the sacrificial layer of the MEMS structure according to an embodiment of the present invention.

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

310: substrate

320: insulation layer

330: sacrificial layer

340: Ribbon Structure

350: piezoelectric

The present invention relates to a MEMS structure and a method of manufacturing the same, and more particularly, to an optical modulator manufactured using a semiconductor process.

MEMS (Micro Electro Mechanical System) is a technology that forms three-dimensional structures on silicon substrates using semiconductor manufacturing technology. The fields of application of MEMS are very diverse, and examples thereof include various sensors for vehicles, inkjet printer heads, HDD magnetic heads, and portable communication devices that are rapidly progressing in miniaturization and high functionality. The MEMS element has an injured portion on the substrate so as to be mechanically operated. Hereinafter, the optical modulator among the MEMS structures will be described. An optical modulator is a circuit or an apparatus that mounts a signal on light (optical modulation) in a transmitter when a free space of an optical fiber or an optical frequency band is used as a transmission medium. Optical modulators are used in the fields of optical memory, optical display, printer, optical interconnection, hologram, etc., and researches on the development of display devices using the same are being actively conducted.

1 is a cross-sectional view of a MEMS structure for a mechanical operation according to the prior art, Figure 2 is a plan view of FIG. 1 and 2, an optical modulator including a substrate 110, an insulating layer 120, a sacrificial layer 130, a ribbon structure 140, and a piezoelectric body 150 is illustrated.

When the wavelength of light is λ, the distance between the ribbon structure 140 and the insulating layer 120 on which the lower reflective layer is formed is equal to λ / 2 when the optical modulator is not deformed (no voltage is applied). Therefore, the total path difference between the light reflected from the ribbon structure 140 and the insulating layer 120 is equal to λ so that light interferes constructively.

In addition, when an appropriate voltage is applied to the piezoelectric body 150, the distance between the ribbon structure 140 and the insulating layer 120 on which the lower reflective layer is formed is equal to λ / 4. Therefore, the total path difference between the light reflected from the ribbon structure 140 and the insulating layer 120 is equal to λ / 2 so that the light interferes with each other. As a result of such interference, the optical modulator may load a signal on the light by adjusting the amount of incident light.

However, according to the related art, there is a problem in that the removal amount of the sacrificial layer 130 is not constant depending on the nonuniformity of the etching rate, the equipment reproducibility, the equipment uniformity, or the position in the wafer according to the difference in the pattern density or the pattern size. . In this case, there are problems such as nonuniformity in driving displacement between wafers (or LOT), nonuniformity of ribbon height, and the like. In addition, in order to shorten the process time, the etching speed of the sacrificial layer needs to be increased, and in order to precisely control the amount of etching in the sidewall direction of the sacrificial layer, there is a problem in that a contradictory situation in which the etching speed is slowed down by precisely adding an etching material coexists. .

The present invention provides a MEMS structure capable of precise etching of a sacrificial layer capable of precisely etching the sacrificial layer used in the MEMS structure and producing a MEMS structure having stable ribbon height and stable operation.

In addition, the present invention provides a MEMS structure capable of precisely controlling the sacrificial layer by precisely etching the sacrificial layer in the lateral direction, and capable of precisely etching the sacrificial layer, which can shorten the manufacturing time, and a method of manufacturing the same. .

In addition, the present invention provides a MEMS structure capable of precise etching of the sacrificial layer capable of precisely controlling the sacrificial layer by increasing the etching area in only a portion in order to precisely etch the sacrificial layer, and a method of manufacturing the same.

The present invention also provides a MEMS structure capable of precise control of the lateral sacrificial layer control egg, and at the same time can precisely etch the sacrificial layer, and a method of manufacturing the same.

Technical problems other than the present invention will be easily understood through the following description.

According to one aspect of the invention, forming an insulating layer on a substrate; Forming a sacrificial layer on the insulating layer; Forming a laminated structure on the sacrificial layer; Forming holes having a sawtooth shape at both ends of the laminated structure; And removing the sacrificial layer using an etchant through the hole.

Here, the insulating layer may be SiO ₂ , and the sacrificial layer may be Si.

Here, the saw tooth shape may be formed by a plurality of grooves.

Here, the sawtooth shape may be formed by a plurality of protrusions.

According to another aspect of the invention, forming an insulating layer on a substrate; Forming a sacrificial layer on the insulating layer; Depositing a ribbon structure on the sacrificial layer; Etching the ribbon structure to form a plurality of ribbons and holes having a sawtooth shape at both ends; And removing the sacrificial layer using an etchant through the hole.

In addition, the MEMS structure manufacturing method according to the present invention may further comprise the step of forming a piezoelectric element for driving the ribbon on the ribbon structure.

Here, the sawtooth shape formed at both ends of the hole may be formed between the piezoelectric body corresponding to the different signals.

According to another aspect of the invention, the insulating layer formed on the substrate; A sacrificial layer formed on the insulating layer and etched according to the preset pattern; The MEMS structure may be provided on the sacrificial layer and includes a ribbon structure having a plurality of ribbons and holes having a sawtooth shape at both ends thereof.

Here, the insulating layer may be SiO ₂ , and the sacrificial layer may be Si.

Here, the saw tooth shape may be formed by a plurality of grooves.

Here, the sawtooth shape may be formed by a plurality of protrusions.

In addition, the MEMS structure according to the present invention may further include a piezoelectric body formed on the ribbon structure to drive the ribbon.

Here, the sawtooth shape formed at both ends of the hole may be formed between the piezoelectric body corresponding to the different signals.

Hereinafter, preferred embodiments of a MEMS structure capable of precise etching of a sacrificial layer and a method of manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings. Components are denoted by the same reference numerals and redundant description thereof will be omitted. In addition, the present invention can be applied to the MEMS structure using the sacrificial layer, it will be described with reference to the optical modulator of the MEMS structure.

The optical modulator element is largely divided into a direct method of directly controlling the on / off of light and an indirect method using reflection and diffraction, and the indirect method may be divided into an electrostatic method and a piezoelectric method. Herein, the optical modulator device may be applied to the present invention regardless of the method of driving or the product name of the manufacturing company (for example, a Grating Light Valve (GLV) device which is an optical modulator of Silicon Light Machine Co., Ltd.).

The electrostatic grating light modulator disclosed in US Pat. No. 5,311,360 includes a plurality of uniformly spaced deformable reflective ribbons having reflective surface portions and suspended above a substrate. An insulating layer is deposited on the silicon substrate. Next, the deposition process of the sacrificial silicon dioxide film and the silicon nitride film is followed.

The nitride film is patterned from the ribbon and a portion of the silicon dioxide layer is etched so that the ribbon is held on the oxide spacer layer by the nitride frame. To modulate light with a single wavelength [lambda] 0, the modulator is designed such that the thickness of the ribbon and the thickness of the oxide spacers are [lambda] 0/4.

The lattice amplitude of this modulator, defined by the vertical distance d between the reflective surface on the ribbon and the reflective surface of the substrate, is the conduction of the ribbon (reflective surface of the ribbon serving as the first electrode) and the substrate (substrate serving as the second electrode). Film).

3 is a perspective view of a diffractive optical modulator using a sacrificial layer according to a preferred embodiment of the present invention. Referring to FIG. 3, a substrate 310, an insulating layer 320, a sacrificial layer 330, a ribbon structure 340, and a piezoelectric material 350 are included.

The substrate 310 is a general semiconductor substrate, and the insulating layer 320 formed on the substrate prevents further etching when the sacrificial layer 330 is etched. Here, the insulating layer 320 is formed of a material having a high selectivity with respect to an etchant for etching the material used as the sacrificial layer (where the etchant is an etching gas or an etching solution). For example, the sacrificial layer 330 may be formed of Si, and the insulating layer 320 may be formed of Si0 ₂ having a high selectivity with respect to a gas or a solution for etching Si. The insulating layer 320 may be coated with a reflective layer (not shown) to reflect incident light.

The sacrificial layer 330 is formed on the insulating layer 320 and then etched by the holes formed in the ribbon structure 340. Therefore, the ribbon structure 340 and the insulating layer 320 are spaced apart by a predetermined distance to form a predetermined interval. Each of the ribbons formed in the ribbon structure 340 using this spacing reflects light to modulate the signal into light. Here, in the case of the optical modulator, the ribbon structure 340 has been described as a center, but in the case of a general MEMS structure, a laminated structure is formed, and the laminated structure may have various shapes and functions spaced apart from the insulating layer 320. . Here, each ribbon of the ribbon structure 340 is deformed by the piezoelectric member 350, and the predetermined light emitted from the light source is reflected and diffracted to each deformed ribbon.

Here, the piezoelectric element 350 formed on the ribbon structure 340 to drive the ribbon may be provided as necessary. Referring to FIG. 3, four piezoelectric members 350 are provided, and two ribbons are controlled by two piezoelectric members 350. Therefore, there are four ribbons extending in the transverse direction, and a single set of two is controlled by two piezoelectric members 350 at both ends. Therefore, the two ribbons forming one set are moved up and down by the piezoelectric body 350 in the same manner, and thus can output the same signal.

Here, two ribbons forming one set are separated by long narrow holes, and these sets are separated by longer holes. The present invention relates to a method for increasing the area during etching by modifying the shape of the hole formed in the ribbon structure. Therefore, the part to which the present invention is applied is both ends of the hole formed in the ribbon structure, and the tooth-shaped pattern is formed on both ends to increase the area during etching. That is, in order to precisely control the sacrificial layer, all parts of the hole may be sawtooth-shaped, but in this case, there is a problem in that the etching time increases. Therefore, a sawtooth pattern is formed only at both ends of the hole requiring precise control.

Such a hole may be a hole formed between two ribbons forming one set, or may be a hole separating each set, that is, a hole formed between piezoelectric members 350 corresponding to different signals. Hereinafter, the latter will be described.

In the above, a perspective view of a MEMS structure capable of precise etching of the sacrificial layer has been described in general. Hereinafter, with reference to the accompanying drawings, a MEMS structure capable of precise etching of the sacrificial layer according to the present invention will be described with reference to specific embodiments. Let's do it. Embodiments according to the present invention are largely divided into two, which will be described in turn below.

4 is a plan view of a diffractive optical modulator capable of precise etching of a sacrificial layer according to a first embodiment of the present invention. Referring to FIG. 4, one end 410 of the sawtooth-shaped hole formed by the insulating layer 320, the ribbon structure 340, the piezoelectric member 350, and the plurality of grooves is illustrated.

A sawtooth-shaped pattern is formed at both ends of the holes separating the sets, that is, the holes formed between the piezoelectric members 350 corresponding to different signals. Since both ends of the hole need to control the etching amount precisely, this part is patterned into a sawtooth shape. A plurality of grooves are formed in the ribbon structure 340 to form a sawtooth shape shown in FIG. The sacrificial layer is etched through the holes formed between the ribbon structures, and one end 410 of the sawtooth-shaped hole having a relatively large etching surface area can be precisely controlled by the etching rate due to the slow etching speed. Here, in the photoresist patterning for the photolithography process, the area to precisely control the sacrificial layer etching amount is patterned in a sawtooth shape.

5 is a plan view of a diffractive optical modulator capable of precise etching of a sacrificial layer according to a second exemplary embodiment of the present invention. Referring to FIG. 5, one end 510 of the sawtooth-shaped hole formed by the insulating layer 320, the ribbon structure 340, the piezoelectric member 350, and the plurality of protrusions (projections) is illustrated. The differences from the first embodiment described above will be mainly described.

A sawtooth-shaped pattern is formed at both ends of the holes separating the sets, that is, the holes formed between the piezoelectric members 350 corresponding to different signals. One end 510 of the sawtooth-shaped hole formed by the plurality of protrusions has a large etching surface area and a slow etching speed due to the smaller amount of etchant that can be injected as a whole compared to the one end 410 of the sawtooth-shaped hole formed by the plurality of grooves. This enables precise control of the etching amount.

6 is a manufacturing process diagram of the diffractive optical modulator using the sacrificial layer of the MEMS structure according to an embodiment of the present invention.

Referring to step (a), the insulating layer 320 is formed on the substrate 310. The insulating layer 320 serves as an etch stop layer.

Referring to step (b), the sacrificial layer 330 is formed on the insulating layer 320. Here, the insulating layer 320 may be SiO ₂ , and the sacrificial layer 330 may be Si. Therefore, the sacrificial layer 330 may be selectively etched by the etchant later.

Referring to step (c), a stacked structure, for example, a ribbon structure 340 is formed on the sacrificial layer 330, and referring to step (d), the piezoelectric member 350 is formed on the ribbon structure 340. To form.

Referring to step (e), the sawtooth-shaped holes are formed at both ends of the stacked structure (ribbon structure 340), and the sacrificial layer 330 is removed using an etchant through the formed holes.

The present invention is not limited to the above embodiments, and many variations are possible by those skilled in the art within the spirit of the present invention.

As described above, the MEMS structure capable of precise etching of the sacrificial layer and the method of manufacturing the same according to the present invention have an effect of precisely etching the sacrificial layer used for the MEMS structure to produce a MEMS structure having a uniform ribbon height and stable operation. There is.

In addition, the MEMS structure capable of precise etching of the sacrificial layer and the method of manufacturing the same according to the present invention can precisely control the sacrificial layer by precisely etching the sacrificial layer in the lateral direction, and can relatively shorten the manufacturing time. There is.

In addition, the MEMS structure capable of precise etching of the sacrificial layer and the method of manufacturing the same according to the present invention have the effect of precisely controlling the sacrificial layer by increasing the etching area only in a portion to precisely etch the sacrificial layer.

In addition, the MEMS structure capable of precise etching of the sacrificial layer and the method of manufacturing the same according to the present invention are capable of precise control of the lateral sacrificial layer control egg, and at the same time has an effect of reducing the etching process time.

Although the above has been described with reference to a preferred embodiment of the present invention, those of ordinary skill in the art to the present invention without departing from the spirit and scope of the present invention and equivalents thereof described in the claims below It will be understood that various modifications and changes can be made.

Claims (13)

Forming an insulating layer on the substrate; Forming a sacrificial layer on the insulating layer; Forming a laminated structure on the sacrificial layer; Forming holes having a sawtooth shape at both ends of the laminated structure; And Removing the sacrificial layer using an etchant through the hole. The method of claim 1, The insulating layer is SiO ₂ , The sacrificial layer is a MEMS structure manufacturing method characterized in that the Si. The method of claim 1, The saw tooth shape is characterized in that formed by a plurality of grooves MEMS structure manufacturing method. The method of claim 1, The sawtooth shape is characterized in that formed by a plurality of protrusions MEMS structure manufacturing method. Forming an insulating layer on the substrate; Forming a sacrificial layer on the insulating layer; Depositing a ribbon structure on the sacrificial layer; Etching the ribbon structure to form a plurality of ribbons and holes having a sawtooth shape at both ends; And Removing the sacrificial layer using an etchant through the hole. The method of claim 5, And forming a piezoelectric body for driving the ribbon on the ribbon structure. The method of claim 6, The sawtooth shape formed at both ends of the hole is formed between the piezoelectric body corresponding to a different signal. An insulating layer formed on the substrate; A sacrificial layer formed on the insulating layer and etched according to the preset pattern; A memes structure formed on the sacrificial layer, comprising a ribbon structure having a plurality of ribbons and holes having a sawtooth shape at both ends. The method of claim 8, Mess structure, characterized in that the insulating layer is SiO ₂ , the sacrificial layer is Si. The method of claim 8, The saw tooth shape is characterized in that formed by a plurality of grooves. The method of claim 8, The sawtooth shape is characterized in that formed by a plurality of protrusions. The method of claim 8, MEMS structure further comprises a piezoelectric body formed on the ribbon structure for driving the ribbon. The method of claim 12, The sawtooth shape formed at both ends of the hole is characterized in that formed between the piezoelectric body corresponding to the different signals.

Images