JP2986127B2 - Drawing method and drawing apparatus for fine pattern - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drawing apparatus for forming a fine pattern having a line width on the order of nanometers.

[0002]

2. Description of the Related Art Conventionally, a drawing apparatus using an electron beam has been used as an apparatus for fine processing in an integrated circuit, which has a thickness of 10 nm.
In general, an electron beam having energy of about 10 kW, which is converged to a diameter of about 10 kW, is incident on a substrate coated with a resist having a thickness of about 1 μm, and the resist is exposed to thereby draw a pattern. . In such an apparatus, since the energy of the electron beam used is large and the resist film thickness is large, it is difficult to draw a pattern of 10 nm or less even in the resist due to the influence of electron scattering and secondary electron range. .

Recently, a method of drawing a finer pattern using a configuration of a scanning tunneling microscope (STM) has been proposed. For example, U.S. Pat. No. 4,785,189 proposes a low energy electron beam lithography apparatus having an STM configuration. In this method, an electrode having a sharp tip is brought close to an electron beam photosensitive resist on a conductive thin film on a substrate, and a resist is drawn by irradiating a low energy electron beam.
Japanese Patent Application Laid-Open No. 2-295050 discloses a micro ST.
A circuit pattern creation device using M has been proposed. This uses a write head in which micro STM chip electrodes are arranged by a semiconductor process. Each chip electrode is opposed to a substrate, and a metal is deposited from an organic metal gas by applying a bias, or a mask is formed by depositing or depositing. That is, a circuit pattern is formed on a substrate by performing etching.

On the other hand, an atomic force microscope (AFM) has been developed [Binnig et al., Phys. Rev. Lett. 56 , 930 (1986)].
Information on surface irregularities can now be obtained in atomic and molecular order. In the AFM, a cantilever (elastic body) that supports a probe approaching a distance of 1 nm or less with respect to a sample surface detects a force in reverse from the amount of deflection caused by the force applied between the sample and the probe. By scanning the sample surface while controlling the distance between the sample and the probe so as to keep the force constant,
This is for observing the three-dimensional shape of the surface with a resolution of nm or less. The AFM does not require the sample to have conductivity unlike the STM, and can be used to observe an insulating sample, particularly a semiconductor resist surface, a biopolymer, or the like in the order of atoms and molecules, and is expected to be widely applied.

[0005]

However, in the above-mentioned conventional example, when the probe electrode is scanned in the lateral direction with respect to the resist surface or the substrate surface, the probe electrode should be kept in contact with the resist surface or the substrate surface in order to avoid destruction of the resist or the resist. It is necessary to finely control the distance between the two. For this purpose, a method of applying a bias voltage between the electrode and the substrate and controlling the position of the electrode in the vertical direction so that the value of the current flowing between the two is kept constant. Take. However, if the thickness of the resist is 3 nm or more, a tunnel current having a value that can be practically detected no longer flows.
Further, when a high voltage bias is applied in order to flow a field emission current instead of a tunnel current, there has been a problem that resist exposure occurs. Therefore, in order for a detectable tunnel current to flow, the resist film thickness must be substantially equal to or less than 3 nm. Exposure occurs even with a weak bias voltage value, and over-etching or resist peeling occurs during the post-exposure process, making it difficult to actually draw a pattern of 10 nm or less.

In addition, when a single probe electrode is used for drawing, it takes a long time to draw a single wafer substrate, so that the throughput is extremely low and there is a practical limit. Therefore, it was necessary to form a plurality of probe electrodes in an array and shorten the time by parallel drawing. However, because there are variations in shape and size due to process errors and undulations on the resist substrate surface between the multiple probe electrodes, the multiple probe electrodes and the resist surface / substrate surface can be used without a mechanism to correct them. There is a risk that the intervals may vary, and the tip of the probe electrode may cause contact destruction with the resist surface or the substrate surface if the interval is too close, or there may be portions where the exposure is not performed because the interval is too long. Yield becomes worse.
Also, in order to perform individual position control of a plurality of probe electrodes, even if an actuator is provided for each probe electrode to perform individual position control, the number of probe electrodes is 100, 1000,.・ ・ In this order, both control system hardware and software become large-scale and complicated.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a fine pattern capable of performing writing at all of a plurality of probe electrode positions with good reproducibility and high stability. This is to provide a drawing method.

According to an embodiment of the present invention that achieves this object, an elastic body having a small elastic constant is used as a member for attaching each of the plurality of probe electrodes, so that the tip of the probe electrode is positioned with respect to the resist surface. The drawing is performed while applying a weak acting force (repulsive force) of about 10 ⁻⁸ N. This allows the distance between the probe electrode and the resist surface to be constant during the horizontal scanning of the pattern drawing without causing a current to flow into the resist (injecting electrons) and without destroying the tip of the probe electrode or the resist surface. Can be maintained. In the present invention, since the resist film thickness can be freely selected,
A resist having a preferable thickness of 1 to 10 nm can be used.

In one embodiment of the present invention, when all the probe electrodes are brought into contact with the resist surface at once, the elastic body is deformed by the acting force (repulsive force) acting between the resist and the individual probe electrodes. Variations in the shape and size between individual probe electrodes due to process errors are absorbed. As a result, without controlling the individual probe electrodes, all the probe electrodes can be controlled to a force below a certain level (~ 10 ^-8
In N), it is possible to approach a certain distance to the resist surface. Also, by detecting the amount of elastic deformation of an elastic body applying the principle of AFM to a part of the arrangement of a plurality of probe electrodes, the force acting between all the probe electrode tips and the resist surface is within a certain range. It is something to keep.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a cross-sectional view of the apparatus of the embodiment as viewed from the side,
FIG. 2 is a sectional view seen from above. In FIG. 1, an elastic support member 101 is fixed to a housing 111, and the elastic support member 101 includes a plurality of probe electrodes 106, 107, and 10.
Plural elastic bodies 1 to which 8, 109 are respectively attached
02, 103, 104 and 105 are supported.

The elastic body having the probe electrode used here is prepared as follows. A SiO ₂ film having a thickness of 0.3 μm is formed on the surface of a Si substrate by thermal oxidation and has a length of 100 μm.
A plurality of elastic bodies having a thickness of 0 μm and a width of 20 μm are patterned. Next, an electric signal wiring pattern to the probe electrode is formed, and anisotropic etching is performed from the back surface of the substrate with a KOH solution to form a plurality of elastic bodies. Subsequently, the height of the elastic body is 5 μm by an electron beam deposition method of carbon or the like.
m probe electrodes are formed. The elastic constant with respect to the deflection of the tip of the plurality of elastic bodies thus created is 0.01 N /.
m. Also, considering the warpage of each elastic body, the process error of the height of the probe electrode, and the like, the elastic body supporting member 10
The variation in the position of the tip of the probe electrode in the height direction with reference to 1 is about 1 μm.

Reference numeral 112 denotes a substrate on which the conductive layer 11 is formed.
3 and the resist 110 are formed to form a drawing medium. As the substrate 112, a substrate having smoothness over a wide area such as a Si wafer, a glass substrate, a sapphire substrate, or a mica cleavage plane is used. A conductive layer 113 of gold, aluminum, platinum, or the like is formed on the substrate 112 to a thickness of about 10 nm. It is formed with a film thickness. At this time, not only a normal vapor deposition method and a sputtering method, but also a conductive layer having a smoother surface is preferably obtained by epitaxially growing the substrate while heating it to several hundred degrees during the process or performing thermal annealing after the process. . PMMA (polymethyl methacrylate), PIBM (polyisobutyl methacrylate),
11/8 AFA diacetylene (pentacosa-10,12
An electron beam photosensitive resist material 110 such as -dinoic acid) or ω-tricosenic acid is applied to a thickness of 1 to 10 nm by an LB method (Langmuir-Blodgett method) or a spin coating method. At this time, in order to uniformly apply the resist with a thickness of several nm, a method of laminating monomolecular films like the LB method is desirable. The elastic constant of the elastic body is smaller than the elastic constant of the resist 110.

A substrate 112 provided with a resist 110 and a conductive layer 113 is fixed on a stage 114, and this stage is moved to an XYθ driving mechanism 115 and Z driving mechanisms 116, 1
17, 201, 202 (described in FIG. 2),
The probe electrodes 106, 107, 108, and 109 are brought closer to desired positions on the surface above the resist 110. This approach will be described in detail. As shown in FIGS. 1 and 2, the laser beams from the laser light sources 118 and 205 are provided on the back surfaces of the probe electrodes 106, 109, 203 and 204 located at the four corners of a plurality of regularly arranged probe electrodes. 119, 120, 206, and 207, and the spot positions of the reflected light are respectively detected by the position detecting elements 12
1, 122, 208 and 209. Then, the substrate 112 is gradually brought closer to the probe electrode in the Z direction in the drawing by the Z drive mechanisms 116, 117, 201, and 202. Probe electrodes 106, 109, 203, 20
4 comes into contact with the upper surface of the resist 110 (approaching to the extent that a repulsive force acts between them), and suppose that the electrode in contact is assumed to be 106, the elastic body 102 to which the probe electrode 106 is attached is attached. Since the elastic deformation (bending) occurs, the position of the reflected light spot on the position detecting element 121 is displaced, and a detection signal whose size changes in accordance with the amount of the displacement is sent to the control computer 123. Here, assuming that the length of the elastic body is l, the optical path length from the back surface of the probe electrode to the position detecting element is L, and the amount of elastic deformation of the tip of the elastic body is Δx, the positional deviation amount of the reflected light spot on the position detecting element Δ
X is represented by ΔX = 2L · Δx / l. Actually l =
Assuming that 100 μm, L = 50 mm, and the displacement detection resolution on the position detecting element is 10 nm, the detection resolution of the amount of elastic deformation Δx is 10 pm, and the force acting between the probe electrode and the resist surface is sufficient. Contact can be detected at a small stage. As described above, if the elastic constant of the deflection of the distal end of the elastic body is made to be about 0.01 N / m, the detectable acting force becomes 10 ⁻¹³ N.

When a signal indicating that the probe electrode 106 has come into contact with the surface of the resist 110 is sent to the position control computer 123,
A drive signal for maintaining the position is transmitted to the Z drive mechanism 116 through the Z position control circuit 124, and further to the other three Z drive mechanisms 117, 201, and 202, the probe electrodes 109, 203, A signal is transmitted to bring substrate 112 closer to 204. In the same manner, the Z drive mechanism of the probe electrode that comes in second contact is held and controlled. Similarly, the remaining two Z drive mechanisms are driven in the Z direction, and when it is detected that the third probe electrode has contacted the surface of the resist 110, the four drive mechanisms 116, 117, 201,
At the same time, the substrate 11 is further moved by ΔZ to the probe electrode.
Bring 2 closer. By performing control in such a step, all the probe electrodes are brought into contact with the surface of the resist 110 without being affected by variations in the position of the plurality of probe electrodes in the Z direction and undulations of the resist surface caused by the manufacturing process. be able to. It is necessary to select the magnitude of ΔZ so that a force that breaks the probe electrode and the resist surface when they come into contact with each other is not applied. In the example of the resist material of the organic thin film described in this embodiment, the threshold value of the breaking force is about 1 ×
It is about 10 ^-7 N. As described above, the variation in the position of the probe electrode in the Z direction and the undulation of the resist surface can be reduced to about 1 μm. Therefore, the elastic constant of the elastic body to which the probe electrode is attached is 0.01 N. / M, the acting force acting between all the probe electrodes and the resist surface can be set to about 2 × 10 ⁻⁸ N (= 0.01 N / m × 1 μm × 2). If the force is of the order of, the destruction between the probe electrode and the resist surface can be avoided. In the present invention, the elastic constant of the elastic body used is a threshold value of the force at which destruction occurs due to the force acting between the probe electrode and the resist,
It is presupposed that the value is smaller than the value obtained by dividing by the maximum value of the variation amount of the distance between each probe electrode and the resist surface.
In the probe electrode material-resist material described in this embodiment, the elastic constant must be smaller than 1 × 10 ⁻⁷ N / z μm = 0.05 N / m.

Hereinafter, the position control computer based on the signal from the position detection element is used so that the elastic deformation (= bending amount) of each elastic body to which the above-mentioned three probe electrodes are attached becomes constant. , The Z-position control circuit drives the respective Z-drive mechanisms to perform the xyθ-direction positioning operation and the drawing operation.

Here, the resist 110 in the xyθ directions
A method of positioning between the probe electrode and each of the plurality of probe electrodes will be described. As described above, all the probe electrodes are
The stage 114 is driven by the xyθ driving mechanism 115 in a state where the surface is in contact with a weak acting force (repulsive force) (about 2 × 10 ⁻⁸ N).
Is subjected to two-dimensional scanning in the xy directions. 3 with 2D scanning
One probe electrode (tentatively a, b, and c) is a resist 11
A change in the acting force due to the unevenness of the zero surface causes a change in the amount of elastic deformation of the elastic bodies a, b, and c attached to each probe electrode. By mapping the drive amount of the Z drive mechanism for driving the elastic deformation amount to be constant with respect to the position of the probe electrode during the two-dimensional scanning, the unevenness information of the probe electrode scanning area on the resist surface is obtained. Can be obtained. FIG. 3 shows an example of the unevenness information on the resist surface corresponding to each of the probe electrodes a, b, and c. In the figure, the mark indicated by "A" is a positioning mark on the virgin substrate that has not been processed yet. As the mark, a characteristic shape such as a scratch or a concavo-convex pattern originally present on the substrate may be used, or a concavo-convex shape created by applying a pulse voltage between the probe electrode and the conductive layer may be used. . In FIG. 3, the mark indicated by “A” is drawn so as to be located at the center of the scanning range of the three probe electrodes a, b, and c, but a shape deviated from the center may be used as the mark. .

A substrate which has been subjected to processes such as lift-off and etching after pattern writing does not reproduce the same position as before the process for each probe electrode due to distortion, an error at the time of resetting, and the like. Therefore, when the unevenness information of the resist surface corresponding to each of the probe electrodes a, b, and c is obtained again,
For example, the position is shifted to the position "d" shown in FIG. At this time, the amount of displacement from before each process is (x
_{a, y a) (x b} , y b) (x c, and y _c). The causes of these shifts include the shifts Δx _1, Δy ₁ in the x and y directions during resetting, the rotational shift Δθ, and the distortion Δx during the process.
_{2 and} Δy ₂ , and the following relationship exists between the displacement and the displacement amount.

[0018]

[Outside 1]

Using these relational expressions, Δx ₁ , Δy
₁ , Δx ₂ , Δy ₂ , Δθ are calculated, and the xyθ driving mechanism 115 is driven by the xyθ position control circuit 125 to correct the positional deviation at the time of resetting. Here, since the distortions Δx ₂ and Δy ₂ at the time of the process cannot be completely corrected, the correction is performed so as to reduce the entire amount of positional deviation (for example, to minimize the deviation of the positional deviation).

Next, a method of pattern drawing will be described. Based on the signal from the drawing control computer 126, the drawing speed for the plurality of probe electrodes is set to the xyθ position control circuit 12.
5. Select using the xyθ drive mechanism 115, and at the same time, apply the drawing pattern signal to the drawing voltage application circuit 127 and the switching circuit 1.
This is applied between the plurality of probe electrodes and the conductive layer 113 via. At this time, when drawing the same pattern for all the probe electrodes, all the circuits may be turned on simultaneously in the switching circuit 128. When drawing a different pattern, the circuits are switched by a switching signal synchronized with the drawing pattern signal. I hope you go.

FIG. 4 shows an example of a pattern drawing process using the drawing apparatus. A voltage of about −10 V is applied between the probe electrode 402 on which a repulsive force of about 10 ⁻⁸ N acts and the conductive layer 403 by the drawing voltage application circuit 405. The substrate 404 is moved to the probe electrode 402 by x, y
By applying a voltage when a position to be drawn is reached while scanning in the two-dimensional direction, a drawn portion 406 indicated by oblique lines in the figure is obtained, for example. Note that a feature of the present apparatus is that Z voltage between the probe electrode 402 and the resist 401 does not need to be applied between the probe electrode 402 and the conductive layer 403.
The resist is not exposed at a position where drawing is not performed to maintain the directional positional relationship.

Next, the respective processes of development, etching, and resist removal are performed to obtain a desired pattern shown at the end of FIG. In the method described in this embodiment, it is desirable that the resist is as thin as possible and can withstand the development process. Specifically, the resist film thickness is 1 to 10
It is selected to be about nm, and since it is a low-energy pattern drawing, it is possible to avoid the spread of the pattern due to the scattered secondary electrons, so that the accuracy and reproducibility are good, and the conductive film having a width of about 1 to 10 nm is formed on the insulating substrate. The fine thin lines can be freely created in the two-dimensional direction at the same intervals.

FIG. 5 shows another example of the pattern drawing process. For example, a conductive layer 502 pattern as shown in FIG. 5 is provided on a substrate 501, and a resist material which becomes conductive by electron beam irradiation, for example, a diacetylene derivative (1
After applying 1/8 AFA diacetylene) 503, 10 ^-8 N
Probe electrode 504-conductive layer 50 on which a repulsion of a certain degree acts
Between the two, a voltage of about −10 V is applied by the drawing voltage application circuit 506. When the substrate 501 is scanned along the desired pattern with respect to the probe electrode 504 in this state, the resist material after scanning becomes conductive (in this embodiment, the conductive material is made conductive by polymerizing a diacetylene derivative). ) Proceeds continuously, and a continuous conductive pattern can be drawn between the patterns of the conductive layer 502 as shown in the figure. According to the method of the present embodiment, similarly to the above-described embodiment, conductive thin wires having a width of about 1 to 10 nm are directly and continuously formed in the two-dimensional direction at the same intervals on the insulating substrate with high accuracy and reproducibility. It can be created by drawing. FIG. 5 is an explanatory view during drawing, but after drawing is completed, a quantum effect device in which electron wave signals passing through the conductive thin wires a and b in the drawing cause quantum interference with each other at a portion c. An example is shown.

FIG. 6 shows a further embodiment of the pattern drawing process. For example, a conductive layer 602 pattern as shown in the figure is provided on a semiconductive substrate 601 and a resist material (similar to the above embodiment) 603 which is made conductive by electron beam irradiation is applied, and then 10 ^-8 N A voltage of about −10 V is applied by the drawing voltage application circuit 606 between the probe electrode 604 and the semiconductive substrate 601 on which a repulsion of about a degree acts. This is applied to the probe electrode 604 with respect to the semiconductive substrate 601.
When a voltage is applied to a position where drawing should be performed while scanning in the x and y two-dimensional directions, the resist material 603 in that portion is made conductive (polymerization in this embodiment). According to the method of the present embodiment, similar to the above-described embodiment, an arbitrary pattern including a pattern shown in the drawing, with high accuracy and reproducibility, is formed on a semiconductive substrate with a conductive fine wire having a width of about 1 to 10 nm. Can be directly drawn in two-dimensional directions at approximately the same intervals. Although the drawing of this embodiment is an explanatory diagram during drawing, after drawing is completed, the electron wave signal transmitted from the conductive layers a to c causes quantum interference in a portion of the periodic structure shown by b in the drawing. An example of such a quantum effect device is shown.

By combining a low-energy electron beam lithography system having a plurality of probe electrodes as described above with a conventional lithography system, an optical stepper, an X-ray stepper or the like, the
It is possible to form portions having various quantum effect functions in a semiconductor device such as SI. Further, since such a fine structure can be simultaneously formed with a plurality of probe electrodes, the throughput (productivity) is improved.

[0026]

As described above, an elastic body having a small elastic constant is used as a member for mounting each probe electrode, and a very weak force (repulsive force) is applied between all the probe electrodes and the resist surface at once. By performing the position control while acting, the pattern drawing at all the probe electrode positions can be performed with good reproducibility and high stability. or,
Exposure of the resist at a position where writing is not performed can be avoided, and destruction of the probe electrode and the resist surface during scanning can be avoided without controlling individual probe electrodes. Therefore, in a drawing apparatus having a plurality of drawing heads (probe electrodes), the hardware and software of the position control system of the probe electrodes can be greatly simplified, and the productivity has been greatly improved.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view illustrating a device configuration of a drawing apparatus.

FIG. 2 is a cross-sectional view showing the configuration of the drawing apparatus.

FIG. 3 is an explanatory diagram of a positioning method in the xyθ direction at the time of substrate resetting.

FIG. 4 is an explanatory diagram of a first embodiment of a drawing method.

FIG. 5 is an explanatory diagram of a second embodiment of the drawing method.

FIG. 6 is an explanatory diagram of a third embodiment of the drawing method.

[Explanation of symbols]

 101 Elastic support member 102-105 Elastic body 106-109 Probe electrode 110 Resist 111 Housing 112 Substrate 113 Conductive layer 114 Stage 115 xyθ drive mechanism 116, 117, 118 Z drive mechanism 119, 120 Beam splitter 121, 122 Position detection Element 123 Position control computer 124 Z position control circuit 125 xyθ position control circuit 126 Drawing control computer 127 Drawing voltage application circuit 128 Switching circuit

──────────────────────────────────────────────────続 き Continuation of the front page (72) Kunihiro Sakai, Incorporated Canon Inc. 3- 30-2 Shimomaruko, Ota-ku, Tokyo (56) References JP-A-3-12504 (JP, A) JP-A-4 -264203 (JP, A) JP-A-4-249704 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01J 37/30 G01B 7/34

Claims (7)

(57) [Claims] 1. A method for drawing a fine pattern on a drawing medium via a plurality of probe electrodes, wherein each of the plurality of probe electrodes is supported by an elastic body, and each of the plurality of probe electrodes and the drawing medium are Wherein the position of the plurality of probe electrodes with respect to the drawing medium is adjusted by deforming the elastic body by a repulsive force generated during the drawing. 2. An apparatus for drawing a fine pattern on a drawing medium via a plurality of probe electrodes, comprising: an elastic body supporting each of the plurality of probe electrodes; and a plurality of the plurality of probe electrodes, and the drawing medium. And a driving unit for causing the resilient body to approach until a repulsive force is generated, and adjusting the positions of the plurality of probe electrodes with respect to the drawing medium by deforming the elastic body by the repulsive force. Device for drawing fine patterns. 3. A method for detecting a position of a specific one of the plurality of probe electrodes when deforming the elastic body, and determining a relative positional relationship between the entire plurality of probe electrodes and a recording medium from the detected position. 2. The method according to claim 1, wherein the calculation is performed, and the whole of the plurality of probe electrodes and the drawing medium are relatively driven based on the calculation result.
3. The drawing method according to claim 1 or the drawing apparatus according to claim 2. 4. The elastic body has one end fixed to a support,
The drawing method according to claim 1 or a drawing apparatus according to claim 2, wherein the drawing method is a beam having a probe electrode disposed at the other end. 5. The elastic constant of the elastic body is 0.05 N / m.
3. The drawing method according to claim 1, wherein the repulsive force of 1 × 10 ⁻⁷ N or less is applied. 6. The drawing method according to claim 1, wherein the drawing medium is a resist material. 7. The drawing method or apparatus according to claim 6, wherein the resist has a thickness of 1 to 10 nm.