KR20040031534A - Method of manufacturing cantilever for data storage device - Google Patents

Abstract

PURPOSE: A method is provided to prevent wear of tips of cantilever by making the tips to have uniform heights, while simplifying manufacturing procedures. CONSTITUTION: A method comprises a first step of forming a plurality of trenches which are spaced apart from each other, by removing a certain part of a silicon layer in a vertical direction from an upper oxide layer of a silicon-on-insulator substrate; a second step of filling the trenches with an oxide film by depositing the oxide film on the upper oxide film, and leaving a certain part of the oxide film by removing curvatures through a lapping process; a third step of attaching a silicon element layer onto the remaining oxide film; a fourth step of defining reference trenches(114a) and adjacent trenches(114b) from among the trenches filled with the silicon oxide film, forming a support area for supporting a cantilever in the silicon element layer arranged in one direction of the reference trench, and forming a cantilever structure in the silicon element layer arranged in the other direction of the reference trench; and a fifth step of floating the cantilever structure by removing the silicon layer arranged in the vicinity of the upper oxide film from the reference trenches to the adjacent trenches.

Description

Method of manufacturing cantilever for data storage device {Method of manufacturing cantilever for data storage device}

The present invention relates to a method for manufacturing a cantilever for an information storage device, and more particularly, manufactured under the same process conditions, to uniform the tip height of each of the arrayed cantilevers, thereby preventing tip wear and information detection error. A piezoelectric sensor and an actuator can be integrated at the same time, and a method for manufacturing a cantilever for an information storage device that can simplify the manufacturing process.

In general, Atomic Force Microscopy (AFM) is a device for measuring the surface shape using a small rod called a cantilever.

The tip of the cantilever is formed a tip (nm) of several nm size, and by measuring the nuclear power between the tip and the specimen, the surface shape, electrical or magnetic properties of the specimen can be known.

Recently, research on nano-lithography devices or nano data storage devices using the principle of nuclear microscope has been actively conducted.

Using the principle of atomic force microscopy, since information can be stored using a probe of a few nm size, a data storage device having a storage density of more than Tera bit / in ² can be developed.

1 is a cross-sectional view of a cantilever applied to a nuclear microscope information storage device according to the prior art, wherein a silicon oxide film 8 is formed on the silicon support 9, and a cantilever made of silicon on the silicon oxide film 8. (7) is formed, a heater platform (5) is formed at the end of the cantilever (7), the heater platform (5) is through the region (6) high-doped to the cantilever (7) And an electrode pad 4 penetrating the silicon nitride film 3.

This cantilever formed a two-dimensional array of 32 x 32 cantilevers, which IBM used for atomic force microscopy information storage.

Referring to FIG. 2, the recording process of the information storage device is performed by heating the silicon tip 1 to reduce the viscosity of the polymer recording medium 22 formed on the silicon substrate 21, and then the silicon tip ( When local force is applied to 1), the information storage groove 23 is formed in the recording medium 22.

Meanwhile, as shown in FIGS. 3A and 3B, the reading process of the atomic force microscope information storage device uses the principle that the cooling rate of the heater is changed according to the distance between the heater platform and the recording medium.

More specifically, as shown in FIGS. 3A and 3B, the silicon tip 1 enters into the concave information storage groove 23 of the recording medium 22, so that the heater platform 5 and the recording medium 22 are separated. As the distance between the heaters 5 approaches, the heater platform 5 cools quickly, and when the silicon tip passes through the flat surface of the recording medium, the distance between the heater platform 5 and the recording medium 22 becomes far and slowly cooled.

Due to this difference in cooling rate, if the temperature of the heater platform 5 is changed, this causes a difference in the electrical resistance of the heater platform 5, so that information is read using this method.

The IBM-developed cantilever for nuclear microscope data storage device has the advantage of simple manufacturing process.However, when manufacturing cantilever arrays, tip wear problems, resistive heater uniformity problems, and heater resistance changes due to height variations between cantilevers are made. When the data is detected and the data is reproduced, the heater is heated to a high temperature of about 350 ° C., which causes problems such as power consumption.

More specifically, the problem of manufacturing cantilever for nuclear microscope information storage device developed by IBM,

First, when the cantilevers are arrayed and formed in parallel in order to speed up the atomic force microscopy information storage device, the deviation of each layer of the SOI substrate and the deviation of the etching process during the manufacturing process are generated, so that the tips of each cantilever are formed to have a uniform height. Therefore, a deviation occurs between the recording medium and the respective cantilever tips.

This height deviation is about 80 nm or more, which is much greater than 40 nm in the depth of the information storage groove, so that when the atomic force microscope information storage device records / reads, the reliability is greatly degraded and the wear problem of the tip becomes serious.

Second, when manufacturing the arrayed cantilever, the resistive heater platform was formed unevenly, so that reliability in reading could not be ensured.

On the other hand, in the case of using a piezoresistive sensor, there is still a problem in that the height deviation of the cantilever and the piezoelectric resistance deviation of each cantilever are generated as in the conventional method of manufacturing a cantilever.

Accordingly, the present invention has been made to solve the problems described above, manufactured under the same process conditions, to equalize the tip height of each cantilever array to prevent tip wear and information detection error, piezoelectric sensor The purpose of the present invention is to provide a method of manufacturing a cantilever for an information storage device that can simultaneously integrate an actuator and simplify a manufacturing process.

A preferred aspect for achieving the above object of the present invention is a plurality of trenches spaced apart from each other by removing a portion of the silicon layer adjacent to the upper oxide film from the upper oxide film of the silicon on insulator (SOI) substrate. Forming a field;

Depositing an oxide film on the upper oxide film to fill an oxide film in the plurality of trenches, and removing a bend by polishing to leave a portion of the oxide film;

Attaching a silicon device layer on which an oxide film is formed on the remaining oxide film;

Among the plurality of trenches filled with the silicon oxide layer, a support region may define reference trenches and trenches adjacent to the reference trenches, and support the cantilever in a silicon device layer in one direction of the respective reference trenches. Forming a cantilever structure in the silicon device layer in the other direction in the respective reference trenches;

A method of manufacturing a cantilever for an information storage device, comprising a fifth step of removing the silicon layer adjacent to the upper oxide layer from the reference trenches to adjacent trenches to float the cantilever structures.

Another preferred aspect for achieving the object of the present invention is a plurality of trenches spaced apart from each other from the top oxide film of the silicon on insulator (SOI) substrate to a portion of the silicon layer adjacent to the top oxide film. Forming a first step;

Depositing an oxide film on the upper oxide film to fill an oxide film in the plurality of trenches, and removing a bend by polishing to leave a portion of the oxide film;

Forming a support region for supporting the cantilever in a silicon layer in one direction of the reference trenches and forming a cantilever structure in the silicon layer in the other direction of the reference trenches;

A method of manufacturing a cantilever for an information storage device, comprising a fourth step of removing the silicon layer under the cantilever structure to float the cantilever structures.

1 is a cross-sectional view of a cantilever applied to the atomic force microscope information storage device according to the prior art.

2 is a schematic perspective view showing a state in which a conventional atomic force microscope information storage device records.

3A and 3B are views illustrating a reading process of a conventional atomic force microscope information storage device.

4A to 4G are manufacturing process diagrams of a cantilever for an atomic force microscope according to a first embodiment of the present invention.

5A to 5F are manufacturing process diagrams of a cantilever for an atomic force microscope according to a second embodiment of the present invention.

6A to 6H are manufacturing process diagrams of a cantilever for an atomic force microscope according to a third embodiment of the present invention.

7 is a schematic perspective view of a cantilever array made in accordance with the present invention.

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

110,210,310: SOI substrate

111,113,115,116,211,213,215,217,218,311,313,315,317,318: silicon oxide film

112,212,214,312,314: Silicon layer 114,216,316: Trench

120: silicon element layer 131,221,321: heater platform

133,233,333: Electrode pad 134,234,334: Piezoelectric sensor

400: cantilever

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

4A to 4G are manufacturing process diagrams of a cantilever for a nuclear microscope according to a first embodiment of the present invention. First, in FIG. 4A, the first silicon oxide film 111, the first silicon layer 112, and the second silicon oxide film ( A silicon on insulator (SOI) substrate 110 having sequentially formed 113 is prepared.

Thereafter, a portion of the first silicon layer 112 is removed from the second silicon oxide layer 113 in the vertical direction to form a plurality of trenches 114 spaced apart from each other (FIG. 4B).

The trenches are preferably formed by a deep reactive ion etching (RIE) process. In the first embodiment of the present invention, the trenches are formed to have a width of about 2 μm.

Next, a third silicon oxide film 115 having a thickness of 1.5 μm is deposited on the second silicon oxide film 113 by low pressure chemical vapor deposition (LPCVD) to fill the plurality of trenches 114 with the silicon oxide film. (FIG. 4C)

Subsequently, in order to remove the bending of the deposited silicon oxide film, the upper third silicon oxide film 115 and the second silicon oxide film 113 are polished and removed by a CMP process. At this time, the remaining silicon oxide film 116 has a thickness of about 0.5 mu m (FIG. 4D).

Thereafter, the silicon device layer 120 having the oxide film 121 formed thereon is adhered to the upper portion of the polished silicon oxide film 116, and then heat treated at about 1100 ° C. for 2 hours, and a chemical mechanical polishing (CMP) process is performed. Polish with (Fig. 4e).

Herein, among the plurality of trenches filled with the silicon oxide layer, reference trenches 114a and trenches 114b adjacent to the reference trenches 114a are defined.

Subsequently, a support region for supporting the cantilever is formed in the silicon element layer in one direction of the respective reference trenches 114a, and in the silicon element layer in the other direction in the respective reference trenches 114a. The cantilever structure is formed to the inner side of the adjacent trenches 114b, and the oxide layer 121 in the region between the cantilever structure and the trenches 114b adjacent to the reference trenches 114a is removed to form a silicon device layer. (FIG. 4F).

The silicon support region and the cantilever structure may include a heater platform 131 including a tip formed on the silicon device layer, a high doped region 132 connected to the heater platform 131, and formed on the silicon device layer; An electrode pad 133 connected to the high doped region 132 through the oxide layer 121 formed on the silicon element layer, and formed on the oxide layer 121 and formed on the lower electrode / PZT layer / upper electrode. It may be formed of a piezoelectric sensor 134 made of.

Therefore, the piezoelectric sensor and the actuator can be manufactured at the same time.

Finally, the exposed silicon device layer from the reference trenches 114a to adjacent trenches 114b is removed with XeF ₂ gas to float the cantilever structures (FIG. 4G).

For reference, FIGS. 4F and 4G are enlarged cross-sectional views of FIG. 4E.

As such, the cantilever structure removes the silicon device layer from the reference trench to the adjacent trench, so the manufacturing process is simple, and since each cantilever can be manufactured identically under the same process conditions, the height of each tip is the same. It can be maintained.

5A to 5F are manufacturing process diagrams of a cantilever for an atomic force microscope according to a second embodiment of the present invention. In FIG. 5A, a first silicon oxide film 211, a first silicon layer 212, and a second silicon oxide film 213 are illustrated. In addition, a silicon on insulator (SOI) substrate 210 having a second silicon layer 214 and a third silicon oxide layer 215 sequentially formed is prepared.

Next, a portion of the first silicon layer 212 is removed from the third silicon oxide layer 215 in the vertical direction to form a plurality of trenches 216 spaced apart from each other (FIG. 5B).

Here as in the first embodiment, the trenches are preferably formed by a Deep RIE process.

In this case, the trenches may be formed through the second silicon layer 214 and the second oxide layer 213 to etch the first silicon layer 212 by about 20 to 50 μm.

Thereafter, a fourth silicon oxide film 217 having a thickness of 1.5 μm is deposited on the third silicon oxide film 215 by low pressure chemical vapor deposition (LPCVD) to fill the plurality of trenches with silicon oxide film. 5c)

Subsequently, in order to remove the bending of the deposited silicon oxide film, the silicon oxide film is polished by a CMP process. (FIG. 5D)

Here, the silicon oxide film 218 of about 7 μm is left in the polishing process.

At this time, among the plurality of trenches, reference trenches 216a and trenches 216b adjacent to the reference trenches 216a are defined.

A support region for supporting the cantilever is formed in the second silicon layer in one direction of the respective reference trenches 216a, and the cantilever is formed in the second silicon layer in the other direction in the respective reference trenches 216a. A structure is formed to the inner side of the adjacent trenches 216b, and the oxide layer 218 of the region between the cantilever structure and the trenches 216b adjacent to the reference trenches 216a is removed to form a second silicon layer. (FIG. 5E).

Here too, the support area and the cantilever structure include a piezoelectric sensor having a lower electrode / PZT film / upper electrode.

In this case, a heater platform 221 including a tip is formed at the tip of the second silicon layer, a high doped region 232 connected to the heater platform 221 is formed, and penetrates the oxide film 218. The electrode pad 233 connected to the high doped region 232 is formed, and the piezoelectric sensor 234 described above is formed on the oxide film 218.

Finally, the exposed first silicon layer from the reference trench 216a to adjacent trenches 216b is removed with XeF ₂ gas to float the cantilever structure (FIG. 5F).

For reference, FIGS. 5E and 5F are enlarged cross-sectional views of FIG. 5D.

6A to 6H are manufacturing process diagrams of a nuclear microscope cantilever according to a third embodiment of the present invention. In FIG. 6A, a first silicon oxide film 311, a first silicon layer 312, and a second silicon oxide film 313 are illustrated. In addition, a silicon on insulator (SOI) substrate 310 having a second silicon layer 314 and a third silicon oxide layer 315 sequentially formed is prepared.

Next, the trench 316 is formed from the third silicon oxide film 315 to a part of the first silicon layer 312 in the vertical direction (FIG. 6B).

Thereafter, a fourth silicon oxide film 317 is deposited on the third silicon oxide film 315 by low pressure chemical vapor deposition (LPCVD) to fill the trench 316 with the silicon oxide film (FIG. 6C).

Subsequently, in order to remove the bending of the deposited silicon oxide film, the fourth silicon oxide film 317 is polished by a CMP process. (FIG. 6D)

Here, the silicon oxide film 318 of about 7㎛ is left in the polishing process.

Thereafter, the silicon element layer 320 on which the oxide film 321 is formed is bonded to the upper part of the polished remaining silicon oxide film 318, and then heat-treated at about 1100 ° C. for 2 hours, and polished by a CMP process. 6e)

Next, a support region capable of supporting the cantilever is formed in the silicon element layer in one direction bordering the trench filled with the silicon oxide film, and a cantilever structure is formed in the silicon element layer in the other direction (FIG. 6F).

At this time, the support region and the cantilever structure include a piezoelectric sensor having a lower electrode / PZT film / upper electrode.

In the second silicon layer, a heater platform 321 including a tip is formed at a tip thereof, a high doped region 332 connected to the heater platform 321 is formed, and penetrates the oxide film 318. An electrode pad 333 connected to the high doped region 332 is formed, and the piezoelectric sensor 334 described above is formed on the oxide layer 318.

Finally, the second silicon layer below the cantilever structure is removed with XeF ₂ gas to float the cantilever structure (FIG. 6g).

According to the first to third embodiments of the present invention described above, when the arrayed cantilever is manufactured, as shown in FIG. 7, each cantilever 400 is floated with a cantilever structure under the same manufacturing process conditions.

Accordingly, the cantilever arrayed by the manufacturing method of the present invention has a uniform height of each tip, it is possible to shorten the wear of the tip, compared to the prior art, each of the arrayed cantilever is uniform information detection characteristics As a result, the reliability can be further improved.

As described in detail above, the present invention may be manufactured under the same process conditions, thereby uniformizing the tip height of each of the arrayed cantilevers, preventing tip wear and information detection error, and simultaneously integrating a piezoelectric sensor and an actuator. This has the effect of simplifying the manufacturing process.

Although the invention has been described in detail only with respect to specific examples, it will be apparent to those skilled in the art that various modifications and variations are possible within the spirit of the invention, and such modifications and variations belong to the appended claims.

Claims (6)

Removing a portion of the silicon layer adjacent to the upper oxide layer from the upper oxide layer of the silicon on insulator (SOI) substrate to form a plurality of trenches spaced apart from each other; Depositing an oxide film on the upper oxide film to fill an oxide film in the plurality of trenches, and removing a bend by polishing to leave a portion of the oxide film; Attaching a silicon device layer on which an oxide film is formed on the remaining oxide film; Among the plurality of trenches filled with the silicon oxide layer, a support region may define reference trenches and trenches adjacent to the reference trenches, and support the cantilever in a silicon device layer in one direction of the respective reference trenches. Forming a cantilever structure in the silicon device layer in the other direction in the respective reference trenches; And a fifth step of floating the cantilever structures by removing a silicon layer adjacent to the upper oxide layer from the reference trenches to adjacent trenches. The method of claim 1, The SOI substrate is, A first silicon oxide film, a first silicon layer, a second silicon oxide film, a method of manufacturing a cantilever for an information storage device, characterized in that the substrate is formed with the second silicon layer and the third silicon oxide film sequentially. The method of claim 1, The SOI substrate is, A method of manufacturing a cantilever for an information storage device, characterized in that the first silicon oxide film, the silicon layer and the second silicon oxide film are sequentially formed. The method of claim 1, The trench is a method of manufacturing a cantilever for an information storage device, characterized in that formed by a Deep RIE (Reactive Ion Etching) process. The method of claim 1, The support region and the cantilever structure, A heater platform 131 including a tip formed on the silicon element layer; A high doped region 132 connected to the heater platform and formed in the silicon element layer; An electrode pad connected to the high doped region 132 through the oxide layer formed on the silicon device layer; And a piezoelectric sensor including a lower electrode, a PZT film, and an upper electrode formed on the oxide film. A first step of forming a plurality of trenches spaced apart from an upper oxide layer of a silicon on insulator (SOI) substrate to a portion of a silicon layer adjacent to the upper oxide layer; Depositing an oxide film on the upper oxide film to fill an oxide film in the plurality of trenches, and removing a bend by polishing to leave a portion of the oxide film; Forming a support region for supporting the cantilever in a silicon layer in one direction of the reference trenches and forming a cantilever structure in the silicon layer in the other direction of the reference trenches; And a fourth step of floating the cantilever structures by removing the silicon layer under the cantilever structure.