JP3148282B2 - Fine processing method of material surface - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for performing fine processing on a material surface such as a wafer.

[0002]

2. Description of the Related Art Conventionally, there has been known a method for applying fine processing to a material surface such as a wafer by applying a scanning tunneling microscope or the like. For example, under extremely low temperature conditions of about 4K,
Atoms are held at the tip of the probe by electrostatic attraction, and the atoms are moved to an arbitrary position on the substrate to be arranged, or a bias voltage applied between the probe and the material is controlled to control an arbitrary position on the substrate. Are exfoliated to form a groove.

[0003]

Among the above-mentioned fine processing methods, the former requires that the probe be operated under severe conditions of extremely low temperature, and it is difficult to arrange atoms three-dimensionally on the surface. Extremely difficult. In the latter case, a scratch is formed on a stable crystal plane,
Since the edge portion is disturbed, the width and depth of the groove cannot be accurately carved at the atomic level.

The present invention provides a fine processing method for forming a crystal surface having desired irregularities on a material surface by pulling up atoms from the material surface (crystal surface) in consideration of the above-mentioned problems. It is intended to be.

[0005]

Means for Solving the Problems The present invention heats a material and causes a needle having a sharp tip to approach a surface of the heated material, and moves the needle from a state where the tip of the needle approaches a material surface. The crystal is pulled up from the material surface by moving the crystal in a direction substantially perpendicular to the material surface.

[0006]

Hereinafter, an embodiment of a method for finely processing a material surface according to the present invention will be described. FIG. 1 is a view showing a configuration of an apparatus used for carrying out a method for finely processing a material surface according to the present invention, and FIGS. 2 and 3 are views showing a surface state of a material formed by the processing method according to the present invention. is there.

In FIG. 1, 1 is a material, 2 is a probe of a scanning tunneling microscope, 3 is a bias power supply, 4x, 4y, 4
z is a piezoelectric element, 5 is a scan generator, 6x, 6
y and 6z are piezoelectric element driving high voltage circuits, 7 is an I / V amplifier,
8 is a log amplifier, 9 is a comparator, 10 is an integrator, 11 is an image amplifier, and 12 is a CPU monitor.

The piezoelectric elements 4x, 4y, and 4z have an X axis and a Y axis, respectively.
The scan generator 5 generates a scanning signal for the probe 2 and the CPU monitor 12. The piezoelectric element driving high voltage generating circuits 6x and 6y drive the piezoelectric elements 4x and 4y of the three-dimensional scanner according to the scanning signal generated by the scan generator 5, and the piezoelectric element driving high voltage generating circuit 6z outputs the output of the integrator 10. By 3
It drives the piezoelectric element 4z of the dimensional scanner.
The first stage I / V amplifier 7 connected to the material 1 converts the tunnel current IT into a voltage and further amplifies it. The log amplifier 8 connected to the next stage is connected to the output signal of the I / V amplifier 7. Performs signal conversion (linearization) so that it has a linear relationship with the height of the probe. The comparator 9 compares the output value of the log amplifier 8 with a reference value corresponding to the set value of the tunnel current, and the integrator 10 integrates the output of the comparator 9 and
This is a control value for the Z-axis piezoelectric element 4z of the dimensional scanner. In this way, the tunnel current IT is fed back to the Z-axis piezoelectric element driving high voltage generation circuit 6z through the I / V amplifier 7, the log amplifier 8, the comparator 9, and the integrator 10 to feed the Z-axis piezoelectric element 4 of the three-dimensional scanner.
By controlling z, the height of the probe 2 is controlled to keep the tunnel current It constant. The signal fed back to the Z-axis piezoelectric element driving high voltage generation circuit 6z is supplied to the image amplifier 11, and the image amplifier 1
The output signal from 1 is supplied to the CPU monitor 12 and modulated in luminance, and the material 1 is displayed as a two-dimensional surface image.

In the apparatus having the above-described configuration, the CP
A position specifying circuit 13 for specifying a point on the material surface is provided corresponding to the image displayed two-dimensionally on the U monitor.
A pointing device 14 such as a mouse or a light pen for specifying an arbitrary point on the screen is connected to the position specifying circuit 13, and when an operator specifies a point on the material surface by the pointing device, A signal indicating the position is held in the position specifying circuit 12, and
The designated point is superimposed and displayed on the image of the material surface two-dimensionally displayed on the CPU monitor.

The above-mentioned material 1 is, for example, a wafer made of a single crystal of silicon, and a power supply 15 is connected to both ends thereof.
Heated to about ° C.

In the method for microfabrication of a material surface according to the present invention, an apparatus having the above-described structure is used.
Hold close to a distance of m. The bias voltage at this time is set to a positive bias or a negative bias depending on the material. From this state, the voltage set for the bias power supply 3 is changed to a voltage near 0 volt.

Thus, the probe stops after approaching further to the surface of the material so as to detect a constant tunnel current. The probe approaches the tip due to an interatomic attractive force or an electric field effect acting between the tip and the atom. At this time, since the constant tunnel current described above is controlled to flow between the material and the probe, the piezoelectric element 4
Retreat by z. By performing this operation continuously, atoms near the probe facing the material surface are pulled up in a chain.

As a result, a columnar or conical projection as shown in FIG. 2 is formed on the surface of the material 1. At this time, a crystal face different from the top face is formed on the side face of the projection formed. From this state, the crystal plane formed by cooling the material is fixed.

At this time, the pointing device 1
When the driver 4 is operated, the output of the position specifying circuit 12 is supplied to the piezoelectric element driving high voltage generating circuits 6x and 6y, and the piezoelectric elements 4x and 4y of the three-dimensional scanner are driven based on the signals of the piezoelectric element driving high voltage generating circuits 6x and 6y. When driven, the probe moves in an arbitrary direction in a plane facing the material surface. Therefore, a belt-like convex portion following the trajectory of the probe is formed on the surface of the material. By forming the belt-shaped protrusions adjacent to each other, a protrusion having an arbitrary area can be formed. Further, by forming the belt-shaped convex portions in parallel at arbitrary intervals, it is possible to form a groove having an arbitrary line width on the surface of the material.

Further, it is possible to form a smaller projection on the top surface of the projection formed by the above-described method.

When a repulsive force acts between the atom at the tip of the probe and the atom on the surface of the material facing the tip,
Bringing the probe closer removes the atoms on the surface of the material. Accordingly, the probe comes closer to the surface of the material. When the probe is moved in this state, the material is removed from the surface of the material by a fixed number of atoms, and a groove is formed.

The above-described embodiment is merely an embodiment of the method for finely processing a material surface according to the present invention, and the present invention can be implemented with various modifications. For example, in the embodiment described above, the material is a single crystal silicon wafer.
The material was pulled to a temperature of about 00 ° C., but the material and the heating temperature are not limited. Further, in the above-described embodiment, the material is heated by electric heating.
The heating of the material may be heating by radiant heat using a heater or the like or heating using a laser or the like. In addition, such a convex portion is also effective in forming a probe on a cantilever used in an atomic force microscope (AFM).

In the above-described embodiment, the probe of the scanning tunneling microscope is used as a needle for processing a material. However, the probe has an extremely sharp tip, and can control an extremely small amount at that position. Can be performed with high accuracy,
The present invention can be implemented without using a probe of a scanning tunneling microscope.

For example, using a device in which a scanning electron microscope and a micromanipulator are combined, a processing position is selected by observing a scanning electron microscope image, a needle is attached to the micromanipulator, and the needle is attached to the heated material. After approaching the surface, the material may be moved in a direction away from the material surface, and may be moved along a predetermined trajectory so that the material is processed into a desired shape. In this case, to bring the needle closer to an appropriate position with respect to the material, a predetermined tunnel current may be detected under a predetermined bias voltage application, or the principle of an atomic force microscope may be used. The needle may be brought closer to the material while measuring the distance between the tip of the needle and the material.

Further, the stylus may be moved by computer control based on the processing target pattern information obtained from a pattern generator or the like to process the target pattern.

[0021]

As is apparent from the above description, according to the method for finely processing a material surface according to the present invention, the material is heated and the needle having a sharp tip is brought close to the surface of the heated material. By moving the tip of the needle close to the material surface in a direction substantially perpendicular to the material surface to pull up the crystal from the material surface, it is possible to cool the material without cooling the material to an extremely low temperature. Can be machined into a material.

Further, according to the present invention, since the material is pulled up or removed at a predetermined atomic level width around the trajectory when the needle is moved, a convex portion or a groove having a desired width is formed. It becomes possible to produce accurately at the atomic level.

[Brief description of the drawings]

FIG. 1 is a view for explaining an apparatus for performing a method for finely processing a material surface according to the present invention.

FIG. 2 is a diagram showing a state of a material surface formed by the material surface fine processing method according to the present invention.

FIG. 3 is a view showing a state of a material surface formed by the material surface fine processing method according to the present invention.

[Explanation of symbols]

1: sample 2: probe 3: bias power supply 4x, 4y, 4z: piezoelectric element 5: scan generator 6x, 6y, 6z: piezoelectric element driving high voltage circuit 7: I / V amplifier 8: log amplifier 9: comparator 10: Integrator 11: Image amplifier 12:
CPU monitor 13: Position designation circuit 14:
Pointing device 15: Heating power supply

Claims (2)

(57) [Claims] 1. A method of heating a material and bringing a needle having a sharp tip close to the surface of the heated material, and moving the needle tip close to the surface of the material from a state close to the surface of the material. A method for finely processing a material surface, wherein a crystal is pulled from a material surface by moving the material in a direction. 2. The method according to claim 1, wherein the needle is a probe of a scanning tunneling microscope.