KR102135368B1 - Method for fabrication of micro oscillating devices - Google Patents

Abstract

The present invention relates to a method for manufacturing a micro-oscillator comprising a spring of uniform and accurate dimensions, the method of manufacturing a micro-oscillator proposed in the present invention, (a) depositing a front mask layer on the front surface of the silicon wafer and the silicon Patterning an area corresponding to an area to form a spring on a wafer, (b) ion into the inside of the silicon wafer through a patterned area of the front mask layer to define a dimension of the spring to be formed on the silicon wafer Forming a buried layer by injecting, and (c) patterning a region corresponding to the buried layer in a rear mask layer deposited on a rear side formed on the opposite side of the front side from the silicon wafer and patterning the patterned region of the rear side mask layer And forming a spring by etching through the buried layer.

Description

Manufacturing method of micro-oscillator{METHOD FOR FABRICATION OF MICRO OSCILLATING DEVICES}

The present invention relates to a microelectromechanical system MICRO ELECTRO MECHANICAL SYSTEMS; MEMS} relates to a method for precisely manufacturing a micro-oscillator using technology, and more particularly, to a technology capable of accurately and accurately manufacturing a shape of a spring, which is the core of the micro-oscillator machine structure.

2. Description of the Related Art With the recent development of MEMS technology and the rapid increase in demand for personal portable devices such as smart phones, personal portable devices have been widely used, and for this reason, the study of ultra-small sensors and actuators applied to the personal portable devices, etc. Development is also active.

Micro devices using MEMS technology typically include sensors and actuators. Examples of sensors include accelerometers, angular accelerometers, pressure sensors, geomagnetic sensors, and examples of actuators include oscillators, micro shutters, and micro scanning mirrors.

Most of these micro-elements include a movable micro-oscillator, and the micro-oscillator mainly operates on the principle of vibrating or resonating. The micro-oscillator is composed of a mass and an elastic spring, and the natural frequency of the micro-oscillator is a very important characteristic that determines the performance of the micro-element. The natural frequency is determined by the mass of the fine oscillator and the elastic modulus of the spring. In particular, the spring has a characteristic that is very sensitive to dimensions since it is generally formed in a very small size compared to the mass body.

Since the elastic modulus of the spring is most sensitive to the smallest dimension in the shape of the spring, it usually has a very large change to the thickness of the spring. Therefore, accurately producing the spring thickness of the fine vibrator is a very important factor in determining the natural frequency of the vibrator.

In the conventional micro-oscillator manufacturing method, the thickness of the spring was produced through a wet or dry etching method. However, in the conventional method, since the depth to be etched is controlled by time, it is difficult to obtain accuracy due to variations in the etch rate of equipment, etc., and there is also a problem that it is difficult to obtain uniformity between elements in a wafer. In addition, since the conventional method uses a method of using the remaining portion excluding the etched depth from the entire wafer thickness to determine the thickness of the spring, the error is further increased because it includes both the deviation of the thickness of the wafer itself and the etch depth. There was also a problem.

Accordingly, it is possible to overcome the problems existing in the conventional micro-oscillator manufacturing method and to consider a new micro-oscillator manufacturing method capable of accurately producing the spring thickness of the micro-oscillator.

Republic of Korea Patent Publication No. 10-1997-0067952 "Method of manufacturing a micro-beam for semiconductor sensors" Republic of Korea Patent Publication No. 10-2000-0013667 "Method of manufacturing a semiconductor acceleration sensor having a window for checking the etching depth"

One object of the present invention is to provide a method of manufacturing a micro-oscillator that ensures an accurate natural frequency of the micro-oscillator and enables production of a micro-element having excellent performance including the micro-oscillator.

Another object of the present invention is to propose a method of manufacturing a micro-oscillator that is relatively less sensitive to the state or deviation of equipment and can secure the uniformity of the inter-element process compared to a conventional bar-up.

Another object of the present invention is to disclose a method of manufacturing a micro-oscillator whose time at which the silicon wafer is etched is independent of time.

In order to achieve such an object of the present invention, a method for manufacturing a micro-oscillator according to an embodiment of the present invention, (a) a region to deposit a front mask layer on the front surface of a silicon wafer and to form a spring on the silicon wafer And patterning the region corresponding to, (b) forming a buried layer by implanting ions into the inside of the silicon wafer through the patterned region of the front mask layer to define the dimensions of the spring to be formed on the silicon wafer. , And (c) patterning a region corresponding to the buried layer in the rear mask layer deposited on the rear side formed on the opposite side of the front side from the silicon wafer, and etching the spring through the patterned region of the rear side mask layer to the buried layer. And forming.

According to an example related to the present invention, step (b) may accelerate and implant oxygen ions or nitrogen ions through a patterned region of the front mask layer to form an oxide buried layer or a nitride buried layer inside the silicon wafer. have.

According to another example related to the present invention, step (b) may be heat treated after the ion implantation to recover the silicon wafer damaged by the ion implantation and to form a uniform buried layer inside the silicon wafer.

According to another example related to the present invention, in the step (b), the implantation energy at the time of ion implantation may be controlled to control the depth at which the buried layer is formed.

According to another example related to the present invention, in the step (b), the concentration of the ions injected into the silicon wafer may be controlled to control the thickness of the buried layer.

According to another example related to the present invention, the front mask layer and the back mask layer deposited on the silicon wafer in steps (a) and (c) may be silicon oxide or silicon nitride.

According to another example related to the present invention, the patterning of the front mask layer and the back mask layer in steps (a) and (c) may be formed through a photo process and an etching process.

According to another example related to the present invention, the back mask layer may be deposited together with the front mask layer or after forming the buried layer.

According to another example related to the present invention, after forming the buried layer and before patterning the back mask layer in step (c), the front mask layer deposited on the front surface of the silicon wafer is removed and the silicon wafer A new front mask layer covering the front side of can be deposited again.

According to another example related to the present invention, the manufacturing method of the micro-oscillator, after the step (c), (d) the front mask layer is removed and the front mask layer newly deposited on the front surface of the silicon wafer is patterned It may further include the step of defining the shape of the micro-oscillator, and etching to form the micro-oscillator.

According to the present invention having the above configuration, since the thickness of the spring in the silicon wafer can be predefined, it is more reliable through a method that is independent of the thickness variation of the silicon wafer during manufacturing of the micro-oscillator and is not sensitive to fluctuations in the etching rate of the equipment. A fine oscillator can be produced.

In addition, the present invention can be applied to mass production because it can manufacture a fine vibrator having an accurate natural frequency, it can bring the effect of cost reduction.

1 is a perspective view of a fine vibrator to be manufactured in the present invention.
Figure 2 is a flow chart showing a method of manufacturing a fine vibrator according to an embodiment of the present invention.
3A and 3B are conceptual diagrams of the steps of patterning the front mask layer to implant ions into the silicon wafer.
4A and 4B are conceptual views of forming a buried layer inside a silicon wafer.
5A and 5B are conceptual views of forming a spring through etching of a silicon wafer.
6A and 6B are conceptual views of steps of forming a micro-oscillator through etching of the rest of the area except the spring.

Hereinafter, a method for manufacturing a fine vibrator according to the present invention will be described in more detail with reference to the drawings. In this specification, the same or similar reference numerals are assigned to the same or similar configurations in different embodiments, and the description is replaced with the first description. As used herein, a singular expression includes a plural expression unless the context clearly indicates otherwise.

1 is a perspective view of a fine vibrator 10 to be manufactured in the present invention.

The micro-oscillator 10 includes a spring 11, a mass 12, and a frame 13.

The spring 11 is mainly formed in a bar shape having a rectangular cross section. The mass body 12 is disposed between both springs 11. The frame 13 is formed with a structure in which at least a part is connected to the spring 11 and surrounds the mass 12 at a position spaced apart from the mass 12. The spring 11 connects the mass 12 and the frame 13 and provides elastic force to the mass 12.

The fine vibrator 10 vibrates or resonates by the mass 12 and the spring 11, or performs linear or rotational motion. The micro-oscillator 10 may be applied as an element component such as a personal portable device.

Typically, the micro-oscillator 10 is manufactured using dry or wet etching of bulk silicon for mechanical reliability. Hereinafter, a method of manufacturing a fine vibrator proposed in the present invention will be described.

2 is a flow chart showing a method of manufacturing a fine vibrator according to an embodiment of the present invention.

The flow chart shown in FIG. 2 shows a process for forming a spring precisely, particularly among a series of manufacturing methods for manufacturing a fine vibrator. The manufacturing method of the micro-oscillator is patterned for implanting ions into the front mask layer 120 of the silicon wafer (S100), implanting ions into the silicon wafer to form a buried layer (S200), and up to the buried layer. And forming a spring through etching (S300).

First, the step (S100) of patterning for ion implantation into the front mask layer 120 of the silicon wafer 110 will be described with reference to FIGS. 3A and 3B.

3A and 3B are conceptual views of step S100 of patterning the front mask layer 120 to implant ions into the silicon wafer 110.

The front mask layer 120 is deposited on the front surface of the silicon wafer 110 or the front mask layer 120 is grown. 3A, a rear mask layer 130 may be deposited or grown along with the front mask layer 120 on the back surface of the silicon wafer 110.

The front mask layer 120 and the rear mask layer 130 are layers that function as an etch mask and may be formed by growth or deposition of silicon oxide or silicon nitride.

After the front mask layer 120 is deposited on the front surface of the silicon wafer 110, patterning is performed on the area 121 corresponding to an area to form a spring on the silicon wafer 110. Patterning may be formed through photolithography and etching. As illustrated in FIG. 3B, when patterning the front mask layer 120, a part of the front mask layer 120 is removed and the front surface of the silicon wafer 110 is partially exposed.

Referring again to FIG. 2, after patterning the front mask layer 120 (S100 ), the patterned region 121 of the front mask layer 120 is defined to define the dimension of the spring to be formed on the silicon wafer 110. Through the implantation of ions into the silicon wafer 110 to form a buried layer (S200).

The step of forming the buried layer (S200) will be described with reference to the drawings of FIGS. 4A and 4B.

4A and 4B are conceptual views of the step S200 of forming the buried layer 140 inside the silicon wafer 110.

When the oxygen ions or nitrogen ions are accelerated and supplied toward the front mask layer 120 of the silicon wafer 110 as shown in FIG. 4A, the oxygen ions and oxygen ions pass through the patterned region 120 as shown in FIG. 4B. Nitrogen ions are injected into the silicon wafer 110 to form a buried layer inside the silicon wafer 110.

The buried layer 140 may be formed of either an oxide buried layer or a buried nitride layer, and the oxide buried layer and the nitride buried layer may be formed by implantation of oxygen ions or nitrogen ions.

The accelerated oxygen ions or nitrogen ions are blocked by the front mask layer 120 that functions as an etch mask in the non-patterned regions (regions other than 120 to 121) and are not injected into the silicon wafer 110. On the other hand, since the accelerated oxygen ions or nitrogen ions are not blocked in the patterned region 120, the oxygen ions or nitrogen ions may penetrate into the silicon wafer 110 through the patterned region 120.

The depth at which the buried layer 140 is formed in the silicon wafer 110 may be controlled by controlling the implantation energy during ion implantation. For example, as the ion implantation energy increases, the buried layer 140 is formed deeper from the surface of the silicon wafer 110. In addition, the thickness of the buried layer 140 may be controlled by controlling the concentration of ions injected into the silicon wafer 110. For example, as the concentration of ions increases, the thickness of the buried layer 140 increases.

Since the dimensions of the spring formed in the etching process to be continued are determined by the depth at which the buried layer 140 is formed and the thickness of the buried layer 140, adjusting the ion implantation energy and ion concentration results in accurate and uniform spring dimensioning. Can be controlled.

After forming the buried layer 140 inside the silicon wafer 110, at a high temperature to recover the silicon wafer 110 damaged by ion implantation and to form a uniform buried layer 140 inside the silicon wafer 110 It can be heat treated.

In the present invention, forming the oxide buried layer 140 or the nitride buried layer 140 inside the silicon wafer 110 utilizes a SIMOX (Separation by Implanted Oxygen) process, which is commonly used for manufacturing silicon on insulator (SOI) substrates. In one example, by forming the oxide buried layer 140 or the nitride buried layer 140 at a desired location on the silicon wafer 110, the purpose of the present invention is to prevent vision from progressing beyond a desired depth by an etch selectivity between silicon and oxide.

Referring again to FIG. 2, after forming the buried layer 140 inside the silicon wafer 110 (S200 ), the spring is formed by etching the buried layer 140 through the rear surface of the back silicon wafer 110 ( S300).

The step of forming the spring (S300) will be described with reference to the drawings of FIGS. 5A and 5B.

5A and 5B are conceptual views of a step S300 of forming a spring through etching of the silicon wafer 110.

In order to etch the back surface of the silicon wafer 110, the area 131 corresponding to the buried layer 140 is patterned on the back mask layer 130 deposited on the back surface of the silicon wafer 110.

After forming the buried layer 140 and before patterning the back mask layer 130, the front mask layer 120 deposited on the front surface of the silicon wafer 110 is removed and the silicon wafer 110 is A new front mask layer 120' covering the front surface may be deposited again.

Patterning may be formed through a photolithography and etching process as described above. As illustrated in FIG. 5A, when patterning the back mask layer 130, a portion 131 of the back mask layer 130 is removed and the back surface of the silicon wafer 110 is exposed.

As shown in FIG. 5B, when the silicon wafer 110 is etched by a wet or dry process, the etch rate when the etch depth reaches the buried layer 140 because the buried layer 140 functions as an etch stop layer Decreases rapidly. Accordingly, etching is performed only up to the buried layer 140, and the remaining area after etching is formed as the spring 111. Since the thickness of the spring 111 from the front surface of the silicon wafer 110 to the previously defined buried layer 140 becomes the thickness of the spring 111, it is possible to manufacture the spring 111 having the correct dimensions.

When manufacturing of the spring 111 is completed, the remaining regions are etched to complete the micro-oscillator.

6A and 6B are conceptual views of steps of forming a micro-oscillator through etching of the rest of the region except the spring 111.

The manufacturing method of the micro-vibrator proposed in the present invention may further include forming a micro-vibrator through etching after the step of forming the spring by etching the buried layer 140 (S300).

Some areas (for removing the patterned front mask layer 120 from the front surface of the silicon wafer 110, depositing a new front mask layer 120' on the front surface of the silicon wafer 110, and fabricating in the shape of a fine pendulum ( 121') again. The removal of the existing front mask layer 120 and deposition of the new front mask layer 120' is preferably performed after the formation of the buried layer 140 is completed or the heat treatment is completed, but is not limited thereto.

As shown in FIG. 6A, the newly deposited front mask layer 120' is patterned to define the shape of the micro-oscillator in the remaining regions 121' except the spring 111, and etching is performed as shown in FIG. 6B. Then, the fine vibrator 100 can be manufactured. The manufactured micro-oscillator 100 includes a spring 111, a mass body 112, and a frame 113 as described in FIG. 1.

In the present invention, the thickness of the desired spring 111 can be set by pre-defining a buried layer 140 having a high etch selectivity with the silicon wafer 110 inside the silicon wafer through ion implantation and heat treatment. In addition, by applying a method that is etched only to a desired depth, a micro-vibrator 100 having a uniform and accurate natural frequency compared to a conventional method and a micro-element including the micro-vibrator 100 can be manufactured.

In addition, since the etching depth for determining the thickness of the spring 111 in the present invention is independent of the time required for etching, it is possible to manufacture an accurate and uniform micro-oscillator 100 without being affected by variations in the etching rate of equipment. .

The manufacturing method of the micro-oscillator described above is not limited to the configuration and method of the above-described embodiments, but the above-described embodiments may be configured by selectively combining all or part of each embodiment so that various modifications can be made. have.

Claims (11)

(a) depositing a front mask layer on the front surface of the silicon wafer and patterning the area corresponding to the area where the spring is to be formed on the silicon wafer;
(b) forming a buried layer by implanting ions into the inside of the silicon wafer through a patterned region of the front mask layer to define a dimension of a spring to be formed on the silicon wafer; And
(c) Patterning a region corresponding to the buried layer in the rear mask layer deposited on the rear side formed on the opposite side of the front side from the silicon wafer, and etching the subsurface mask layer through the patterned region to the buried layer to form a spring. Method of manufacturing a fine vibrator comprising a step of. According to claim 1,
The step (b) is a method of manufacturing a micro-oscillator, characterized in that oxygen ions or nitrogen ions are accelerated and injected through a patterned region of the front mask layer to form an oxide buried layer or a nitride buried layer inside the silicon wafer. According to claim 1,
In the step (b), the silicon wafer damaged by the ion implantation is recovered, and the heat treatment is performed after the ion implantation to form a uniform buried layer inside the silicon wafer. According to claim 1,
In the step (b), a method for manufacturing a micro-oscillator characterized in that the implantation energy during the ion implantation is controlled to control the depth at which the buried layer is formed. According to claim 1,
In the step (b), a method of manufacturing a micro-oscillator characterized in that the concentration of the ions injected into the silicon wafer is controlled to control the thickness of the buried layer. According to claim 1,
The method of manufacturing a micro-oscillator, characterized in that the front mask layer and the rear mask layer deposited on the silicon wafer in steps (a) and (c) are silicon oxide or silicon nitride. According to claim 1,
The patterning of the front mask layer and the back mask layer in the steps (a) and (c) is formed through a photo process and an etching process. According to claim 1,
The rear mask layer is deposited with the front mask layer or after forming the buried layer, characterized in that the deposition method of the micro-oscillator. According to claim 1,
After forming the buried layer, before patterning the back mask layer in step (c), the front mask layer deposited on the front side of the silicon wafer is removed and a new front mask layer covering the front side of the silicon wafer is re-installed. Method of manufacturing a fine vibrator characterized in that the deposition. According to claim 1,
After step (c),
(d) further comprising the step of defining the shape of the fine vibrator by patterning the front mask layer on which the front mask layer is removed and newly deposited on the front surface of the silicon wafer, and forming a fine vibrator by etching. Method of manufacturing an oscillator. A fine vibrator manufactured by the manufacturing method according to any one of claims 1 to 10.

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