JP2008047797A - Imprinting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable an imprinting method utilizing anodic oxidation with a mold having higher mechanical strength and low resistance, such as one made of silicon. <P>SOLUTION: A state with a mold pattern 121 formed is provided by processing a silicon carbide film 102 formed by the chemical vapor deposition process. Then, the mold pattern 121 is contacted with the principal surface of a silicon substrate 131, and a voltage, such as a 20 V, is applied in the contacted state of the mold pattern between a supporting substrate 101 and the silicon substrate 131. Under the voltage application, a current is fed between the mold pattern 121 and the silicon substrate 131 contacted therewith via moisture adsorbed on the contacting surface of the mold pattern 121, so as to enable the anodic oxidation. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an imprint method for transferring an arbitrary pattern by pressing a mold (mold) against a substrate.

  In order to create a semiconductor device such as an LSI, an extremely fine pattern such as a resist pattern used as an etching mask or an etching pattern formed by etching is required. The resist pattern is formed through development and washing (rinsing) after exposing a desired pattern to the photosensitive resin film coated on the substrate. The photosensitive resin film is, for example, a resin film (polymer material) that is sensitive to ultraviolet rays, X-rays, electron beams, and the like, and a powdered or highly viscous liquid material dissolved in an organic solvent is used. In addition, exposure uses UV or electron beam as a light source, uses a master plate with a pattern formed based on element design and circuit (pattern) design, and forms a latent image of the pattern on the photosensitive resin film. It is done by doing.

  However, in the pattern forming method described above, for example, an exposure apparatus which is expensive, for example, several billion yen called a stepper is used. For this reason, in recent years, there is a demand for a technique capable of forming such an extremely fine pattern at a lower cost without using an expensive apparatus. On the other hand, a pattern forming technique called imprint lithography has attracted attention. Imprint lithography is a technique similar to a conventional imprint method. The imprint method is used for producing a DVD (Digital Video Disk) or the like, and is a technique for forming a pattern as shown below.

  The imprint method will be briefly described. First, a pattern serving as a master mold is formed on a silicon substrate using a known photolithography technique. Next, a nickel layer is formed on the master mold by depositing nickel by an electrolytic plating method. Next, the nickel layer (mold) to which the pattern shape of the master mold is transferred is obtained by separating (peeling) the nickel layer from the master mold. Thereafter, the produced nickel mold is pressed against the surface of the aluminum plate, and the pattern shape of the nickel mold is transferred to the aluminum plate. By repeating the transfer of the nickel mold to the aluminum plate, an aluminum plate having the necessary number of patterns transferred thereon can be obtained.

  A technique for producing a resist pattern used for producing a semiconductor device by applying the above-described imprint method is imprint lithography. In imprint lithography, the above-described aluminum plate is replaced with a resin layer such as a resist to form a resist pattern. For example, the resist film is formed on the metal film, the pattern is transferred by pressing the mold onto the resist film in the same manner as described above, and the metal film is etched using the formed resist pattern as a mask. Thus, a wiring layer can be formed.

  Hereinafter, imprint lithography will be briefly described. First, for example, a silicon substrate 401 is prepared as shown in FIG. 4A, and a predetermined mold is formed on the silicon substrate 401 by a known photolithography technique and etching technique as shown in FIG. 4B. It is assumed that the pattern 402 is formed. The silicon substrate on which the mold pattern 402 is formed becomes a master mold. Next, as shown in FIG. 4C, a substrate 420 on which a resin layer 421 made of a resin material such as polymethyl methacrylate (PMMA) is formed is prepared, and a mold pattern 402 of the silicon substrate 401 is formed. The resin layer 421 is pressed against the formed surface, and the resin pattern layer 422 to which the shape of the mold pattern 402 is transferred is formed on the substrate 402 as shown in FIG. By using the resin pattern layer 422 thus formed as a mask, the silicon substrate 401 can be finely processed.

  Recently, a method of forming a pattern by applying a voltage between the mold and the substrate as well as simply pressing the mold against the substrate has been proposed (see Non-Patent Document 1). In this technique, first, as shown in FIG. 5A, a voltage is generated between a mold 501 made of, for example, silicon and formed with a transfer mold pattern 502 and a crystal substrate 521 such as silicon or GaAs. A voltage can be applied by the application unit 505. Here, it is assumed that the crystal substrate 521 side is an anode and the mold 501 side is a cathode.

  Next, as shown in FIG. 5B, the surface of the crystal substrate 521 is brought into close contact with the surface on which the mold pattern 502 is formed, and then a voltage is applied between them. The substrate and the mold may be brought into close contact with a voltage applied. By this voltage application, an oxidized region 522 is formed in the region of the crystal substrate 521 that is in contact with the mold pattern 502. The oxidized region 522 is formed only at a location where the mold pattern 502 of the mold 501 is in contact. Since the oxidized region 522 is formed by so-called anodic oxidation, no current flows in a region where the mold pattern 502 is not in contact, and no anodic oxidation occurs, so that a region to be oxidized is not formed.

Next, as shown in FIG. 5C, after separating the mold 501 from the crystal substrate 521, the crystal substrate 521 is etched using the oxidized region 522 as a mask, as shown in FIG. 5D. Thus, a state in which the pattern 523 is formed on the crystal substrate 521 is obtained. In the above-described anodic oxidation, for example, a current flows between the mold pattern 502 and the substrate 521 via moisture adsorbed on the surface of the mold pattern 502, and the adsorbed water existing between them is electrolyzed to water. Acid ions (OH ⁻ ) are generated, and the generated hydroxide ions are oxidized by oxidizing the substrate surface.

Atushi Yokoo, "Nanoelectrode Lithography", Japanese Journal of Applied Physics, Vol.42, pp.L92-L94, 2003.

  By the way, in the imprint lithography by the technique of the nonpatent literature 1 mentioned above, a low electrical resistance is calculated | required as a characteristic with a molding | mall. In imprint lithography, since the substrate and the mold are warped, a load is applied between the substrate and the mold in order to bring the mold pattern into close contact with the surface of the substrate. For this reason, the mold is required to have high mechanical strength.

  In response to such required characteristics, when silicon as described above is used, it is easy to form a fine shape because the processing technology has been developed, but there are the following problems. First, even when a dopant such as arsenic or antimony is introduced as an impurity, silicon has a resistance value of about 0.01 to 0.02 Ω · cm, and a low electrical resistance cannot be obtained. For this reason, in order to form an oxidation region, a large amount of electric power is required and time is required, resulting in an increase in manufacturing cost. Further, since silicon has a mechanical strength that is not so high, there is a problem that a mold pattern of a formed mold is damaged during transfer. In particular, when the width of the mold pattern is 100 nm or less, the pattern is markedly damaged, many defects are generated, and the yield is lowered.

  In addition, there is a mold made of a metal layer formed by nickel electroforming. However, even with nickel, the mechanical strength does not satisfy the required characteristics, and there is a problem that the warpage of the obtained mold is large due to the presence of internal stress present by nickel electroforming. In addition, the surface flatness is increased due to the influence of the crystal grain size of the nickel layer formed by the nickel current, and there is a problem that it is not easy to obtain a finer transfer pattern with high accuracy.

  As described above, imprint lithography using the conventional technique of Non-Patent Document 1 using a conventional mold causes an increase in manufacturing cost, a high yield cannot be obtained, and a finer pattern can be obtained with high accuracy. There was a problem that it was not easy to form.

  On the other hand, in the imprint lithography based on the technique of Non-Patent Document 1 described above, it is important to adsorb water to the contact surface of the mold pattern as described above, and a uniformly thin adsorbing layer of water is formed on the contact surface. As a result, the anodizing reaction is promoted. However, the contact angle of water on the silicon surface is as low as about 84 ° and the wettability is low, and the surface of silicon repels water. For this reason, in the conventional silicon mold, anodization is difficult to occur in the entire area of the mold pattern that is in contact, and the pattern cannot be transferred accurately, resulting in pattern chipping and the like. As described above, when the mold (mold pattern) is made of silicon, it is easy to form a fine pattern, but there is a problem that the pattern cannot be transferred accurately.

  The present invention has been made in order to solve the above-described problems. An imprint method using anodization using a low-resistance mold having higher mechanical strength than silicon or the like is low cost. The purpose is to be able to perform in a state with a high yield. Another object of the present invention is to make it possible to perform pattern transfer more accurately by an imprint method using anodization by facilitating anodic oxidation over the entire mold pattern surface of the mold.

  The imprint method according to the present invention includes a first step in which a silicon carbide film made of silicon carbide is formed on a support substrate, and a state in which a mold pattern is formed by processing the silicon carbide film. In the second step, the surface of the support substrate on which the mold pattern is formed is pressed against the main surface of the substrate to be processed, and a voltage is applied between them to bring the mold pattern into contact with the surface of the substrate to be processed And a third step in which an oxidized region is formed. A mold pattern made of a silicon carbide film has a higher mechanical strength than when silicon is used, and a lower resistance state than when silicon is used.

  In the imprint method, the silicon carbide film may be made of polycrystalline silicon carbide formed on the support substrate by chemical vapor deposition. The support substrate may be made of a sintered body of silicon carbide powder. The support substrate may be made of silicon.

  Another imprint method according to the present invention includes a first step in which a mold pattern is formed on a support substrate, and a functional layer for controlling water wettability on the upper surface of the mold pattern. The function of the upper surface of the mold pattern is achieved by pressing the surface of the support substrate on which the mold pattern is formed against the main surface of the substrate to be processed and applying a voltage therebetween. And at least a third step in which an oxidized region is formed on the surface of the substrate to be processed that is in contact with the layer. Therefore, the state of the layer of water adsorbed on the surface of the mold pattern that contacts the substrate to be processed can be controlled.

  In the imprint method, in the second step, the functional layer may be formed from a material having higher wettability than the material constituting the mold pattern, so that the wettability of water is increased. In this case, for example, the functional layer may be composed of at least one of titanium, nickel, and cadmium. The functional layer may be formed by oxidizing the surface of silicon.

  As described above, according to the present invention, since the silicon carbide film is processed to form the mold pattern, a mold pattern having higher mechanical strength than silicon or the like and having a low resistance can be obtained. An excellent effect is obtained that the imprint method using oxidation can be performed at a low cost and with a high yield.

  In addition, according to the present invention, since the functional layer for controlling the wettability of water is formed on the upper surface of the mold pattern, anodization is easily performed over the entire mold pattern surface of the mold, and anodization is performed. An excellent effect is obtained that the pattern can be transferred more accurately by the imprinting method used.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a process diagram for explaining an imprint method according to an embodiment of the present invention. First, as shown in FIG. 1A, a support substrate 101 is prepared, and a silicon carbide film 102 is formed thereon. The support substrate 101 is made of, for example, a sintered body of silicon carbide powder (silicon carbide sintered body), and is formed into a disk shape having a diameter of 100 mm and a thickness of 625 μm. Note that the surface of the support substrate 101 does not need to be particularly mirror-finished. The support substrate 101 may be made of silicon.

  Silicon carbide film 102 may be formed by depositing polycrystalline silicon carbide by a low pressure CVD method. The deposition of polycrystalline silicon carbide is usually carried out by a CVD method using a dichlorosilane-acetylene-hydrogen system gas or a silane-propane-hydrogen system gas at a deposition temperature of 800 to 1100 ° C. and a gas pressure of about 50 to 600 Pa. Good. Thus, according to the silicon carbide film 102 formed by the CVD method, a lower resistance state can be obtained as compared with silicon, as will be described later.

  Here, the film thickness of the polycrystalline silicon carbide film to be formed may be determined in consideration of the pattern depth as a mold and the required remaining film thickness. For example, the film thickness may be about 2.5 μm. Next, the surface of the deposited polycrystalline silicon carbide film is polished with a diamond paste to a mirror surface of about 0.5 μm, so that the silicon carbide film 102 is formed. Even when the support substrate 101 is made of silicon, the silicon carbide film 102 can be formed as described above.

  Next, as shown in FIG. 1B, fine processing is performed by a known lithography technique and etching technique to form a mold pattern 121 having fine irregularities as a mold. Here, in order to form a nanometer-class fine pattern, an electron beam resist film is formed on the silicon carbide film 102, and a pattern (latent image) is drawn thereon using an electron beam drawing apparatus, and this is developed. Thus, an etching mask is obtained. Next, the silicon carbide film 102 is selectively etched by reactive ion etching with chlorine gas, and then the etching mask is removed to obtain a state in which the mold pattern 121 is formed.

  Next, a silicon substrate (substrate to be processed) 131 to be a pattern transfer target is prepared, and the oxide film on the surface is removed using buffered hydrofluoric acid. Next, as shown in FIG. 1C, the support substrate 101 and the silicon substrate 131 are arranged so that the surfaces on which the mold patterns 121 are formed are opposed to each other, and the power source 105 is connected to both. Here, the silicon substrate 131 is connected to the support substrate 101 (mold pattern 121) serving as a mold so as to have a positive potential, the silicon substrate 131 is used as an anode, and the support substrate 101 is used as a cathode. And As the power source 105, a general constant voltage power source may be used. For example, model R6242 manufactured by Advantest Corporation is applicable.

  Next, as shown in FIG. 1D, the mold pattern 121 is brought into contact with the main surface of the silicon substrate 131, and a voltage is applied between the support substrate 101 and the silicon substrate 131 in this state. It is assumed that For example, a pulse voltage of 20V is applied. In this voltage application, current flows between the mold pattern 121 and the silicon substrate 131 in contact with the moisture through the moisture adsorbed on the contact surface of the mold pattern 121, and anodization is performed. The flowing current is about 1 to 2A. By continuing this voltage application time for about 30 seconds to 1 minute, the mold pattern 121 is transferred as an oxidized region 132 formed on the main surface of the silicon substrate 131.

  Next, as shown in FIG. 1E, after the support substrate 101 is released from the silicon substrate 131, the silicon substrate 131 is etched using the oxidized region 132 as a mask pattern as shown in FIG. 1F. As a result, a state in which the pattern 133 is formed on the silicon substrate 131 is obtained. As this etching method, an etching method in which an etching selection ratio between the oxidized region 132 and the silicon substrate 131 can be obtained may be used. For example, using an electron cyclotron resonance (ECR) plasma etching apparatus, chlorine gas as an etching gas is supplied to about 0.1 Pa in the plasma generation chamber, and a magnetic field of electron cyclotron resonance conditions is generated in the plasma generation chamber. Then, a 2.45 GHz microwave (for example, 300 W) is introduced into the plasma generation chamber to generate ECR plasma by the supplied chlorine. The etching may be performed by the plasma generated in this manner and released into the processing chamber by the divergent magnetic field.

  Hereinafter, the support substrate will be described. First, the resistance value will be described. As described above, even when silicon is a low-resistance silicon substrate, resistance can be reduced to 0.01 to 0.02 Ω · cm by adjusting the dopant. On the other hand, silicon carbide has a resistance of 0.02 Ω · cm as in the case of silicon with respect to the sintered body (reference: Shin-Etsu Group Material Guide / Semiconductor Material Page).

  On the other hand, it is known that a silicon carbide film formed by the CVD method as described above is in a lower resistance state. As described above, the resistance of the polycrystalline silicon carbide film formed by the CVD method is found to be smaller than 0.01 Ω · cm by the four-end needle measurement method. It has been found that silicon carbide has a lower resistance than silicon by introducing a dopant, and when a film is formed by a CVD method, ions from constituent elements of the source gas are introduced as impurities. It is considered that low resistance has been developed.

  Next, mechanical strength will be described. First, the mechanical strength of the mold can be evaluated by Vickers hardness. For example, the Vickers hardness of silicon, nickel electroformed product, and quartz is about 1050, 500, and 950, respectively. On the other hand, it is known that the Vickers hardness of silicon carbide is several times larger than that of silicon, and particularly 2200 for the sintered silicon carbide. For example, the breakdown voltage at which the mold pattern is broken was measured with a mold made of silicon carbide produced in the same manner as described above and a silicon mold produced in the same manner as before. As a result, it was found that in the silicon mold, the pattern portion started to be broken at a load of 40 kg, whereas in the silicon carbide mold, the pattern was not broken even at a load of 100 kg. Thus, it turns out that silicon carbide is a material which satisfies the requirements (high mechanical strength and low resistance) as a mold in the voltage imprinting method. Therefore, by using silicon carbide, an imprint method for applying a voltage can be performed efficiently.

  As described above, the silicon carbide sintered body has the highest hardness, but since it is a sintered body, gaps called pores are formed between crystal grains. For this reason, when the mold pattern is directly formed on the substrate of the silicon carbide sintered body, it is difficult to obtain pattern uniformity, which becomes remarkable when the width of the mold pattern is 100 nm or less. In contrast, as described above, a polycrystalline silicon carbide film having the same composition and the same thermal expansion coefficient is formed on a support substrate made of a silicon carbide sintered body by a low pressure vapor phase growth (CVD) method. By forming a mold pattern on the polycrystalline silicon carbide film, pattern uniformity can be obtained. Further, the mold formed in this way can have a very small warp of 1 μm or less.

  Further, when the mold pattern is constituted by the polycrystalline silicon carbide film as described above, the support substrate is not limited to silicon carbide but may be a silicon substrate having a low resistance, for example. In such a case, as shown in FIG. 2, a silicon carbide film 102 is formed on the main surface of the support substrate 101 and a similar silicon carbide film 202 is formed on the back surface of the support substrate 101 (a), The silicon carbide film 102 may be processed to a state (b) in which the uneven mold pattern 121 is formed. Since the polycrystalline silicon carbide films having the same film thickness are formed on both surfaces of the support substrate 101, warping of the mold due to internal stress is suppressed. In addition, the film thickness of the polycrystalline silicon carbide film for forming the mold pattern may be equal to or higher than the height (film thickness) of the pattern to be formed.

  Next, another embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a process diagram for explaining another imprint method according to the embodiment of the present invention. First, as shown in FIG. 3A, a support substrate 301 is prepared. The support substrate 301 is, for example, a rectangular substrate having a side of 20 mm made of a silicon carbide sintered body. Note that the surface of the support substrate 301 does not need to be particularly mirror-finished. The support substrate 301 may be made of silicon.

  Next, as shown in FIG. 3B, a state in which a fine uneven mold pattern 321 as a mold is formed on the main surface of the support substrate 301 by fine processing using a known lithography technique and etching technique. And Here, in order to form a nanometer-scale fine pattern, an electron beam resist film is formed on the support substrate 301, and a pattern (latent image) is drawn thereon using an electron beam drawing apparatus, and this is developed. Etching mask. Next, the support substrate 301 is selectively etched by reactive ion etching with chlorine gas, and then the etching mask is removed to obtain a state in which the mold pattern 321 is formed.

  Next, the functional layer 322 made of, for example, titanium and controlling the wettability of water is formed on the upper part (upper surface) of the formed mold pattern 321. For example, the functional layer 322 may be formed by depositing titanium on the mold pattern 321 by a known sputtering method using titanium metal. The functional layer 322 made of titanium to be formed may have a thickness of about 20 nm. The titanium has a water contact angle of 0 ° and has very good wettability.

  Next, a silicon substrate (substrate to be processed) 331 to be a pattern transfer target is prepared, and the oxide film on the surface is removed using buffered hydrofluoric acid. Next, as shown in FIG. 3D, the support substrate 301 and the silicon substrate 331 are arranged so that the surfaces on which the mold pattern 321 is formed are opposed to each other, and the power source 305 is connected to both. Here, the silicon substrate 331 is connected to the support substrate 301 (mold pattern 321) as a mold so as to have a positive potential, the silicon substrate 331 is used as an anode, and the support substrate 301 is used as a cathode. And As the power source 305, a general constant voltage power source may be used. For example, model R6242 manufactured by Advantest Corporation is applicable.

  Next, as shown in FIG. 3E, the functional layer 322 formed on the mold pattern 321 is in contact with the main surface of the silicon substrate 331. In this state, the support substrate 301 and A voltage is applied between the silicon substrate 331 and the silicon substrate 331. For example, a pulse voltage of 20V is applied. In this voltage application, an electric current flows between the functional layer 322 and the silicon substrate 331 in contact with the functional layer 322 through moisture adsorbed on the contact surface of the functional layer 322, and anodization is performed. The flowing current is about 1 to 2A. By continuing this voltage application time for about 30 seconds to 1 minute, the mold pattern 321 is transferred as an oxidized region 332 formed on the main surface of the silicon substrate 331.

  Next, as shown in FIG. 3F, after the support substrate 301 is released from the silicon substrate 331, the silicon substrate 331 is etched using the oxidized region 332 as a mask pattern as shown in FIG. 3G. Thus, a state in which the pattern 333 is formed on the silicon substrate 331 is obtained. As this etching method, an etching method in which an etching selectivity between the oxidized region 332 and the silicon substrate 331 can be used. For example, using an etching apparatus using electron cyclotron resonance (ECR) plasma, chlorine gas as an etching gas is supplied to be about 0.1 Pa in the plasma generation chamber, and a magnetic field under electron cyclotron resonance conditions is supplied into the plasma generation chamber. After the generation, a 2.45 GHz microwave (for example, 300 W) is introduced into the plasma generation chamber to generate ECR plasma by the supplied chlorine. The etching may be performed by the plasma generated in this manner and released into the processing chamber by the divergent magnetic field.

Hereinafter, the functional layer 322 for controlling the wettability of water will be described in more detail.
In anodic oxidation, water intervening between a pattern transfer target substrate and a mold pattern portion in contact with the substrate is “2H ₂ O-4e ⁻ → O ₂ (or oxygen radical: 2O ·) + 4H ⁺ ”. It is carried out by electrolysis according to the reaction. Oxygen or oxygen radicals generated by this electrolysis oxidize the surface of the substrate which is an anode, and an oxidized region is formed on the surface of the substrate by anodic oxidation.

  Therefore, the progress of the anodic oxidation reaction is related to the amount of water adsorbed on the contact surface. The amount of water adsorbed varies depending on the humidity of the atmosphere. For example, when the humidity of the atmosphere is 40% or less, anodic oxidation hardly occurs. On the contrary, when the humidity of the atmosphere is 60% or more, particularly 80% or more, anodization easily proceeds.

  Thus, the intervention of water is important, and it is important for imprinting over a large area that water adheres thinly and uniformly to the upper surface of the mold pattern of the mold. This adsorption of water is controlled by the wettability of water on the upper surface of the mold pattern of the mold, and a measure for evaluating this is the contact angle of water on the upper surface. If the contact angle is small and the wettability is high, the adsorbed water spreads smoothly over the entire upper surface of the mold pattern in a uniform state. On the other hand, if the contact angle is large and the wettability is low, the adsorbed water comes to be repelled and partially exists in a ball shape. In such a state, the anodic oxidation does not occur in a uniform state over the entire area of the contacting pattern portion, and the oxidized region cannot be formed uniformly. As a result, the pattern is not formed uniformly.

  On the other hand, by providing a functional layer made of a material having higher wettability than the material constituting the mold pattern on the upper surface of the mold pattern, the adsorbed water is suppressed from being repelled. It spreads more smoothly in a uniform state throughout. In this manner, by providing a functional layer and controlling wettability, the state of the layer formed by water adsorbed on the surface in contact with the substrate to be processed can be controlled.

Below, the contact angle of water with respect to various metals is shown.
Ag: 85 °, Au: 85 °, Rh: 65 °, Pd: 74 °, Pt: 50 °, Ti: 0 °, Ni: 0 °, Cd: 0 °.

Further, TiO ₂ is a material having a water contact angle of 0 °, but its electrical conductivity is lower than that of a metal material. Accordingly, preferred materials are titanium (Ti), nickel (Ni), and cadmium (Cd) (reference: Chemical Handbook / Basic, Chemical Society of Japan).

  For example, when the contact angle of water with respect to the thin film formed by the sputtering method was compared, Si: ~ 84 °, SiC: ~ 20 °, Pt: ~ 35 °, Ti: ~ 20 °. Although it is a little different from the above literature values due to the difference in crystal state, etc., it has been experimentally proved that titanium is a metal with a very small contact angle. It has been found that when pattern formation is actually performed using a mold in which these materials are formed on the surface, the frequency of pattern chipping decreases in proportion to the decrease in the contact angle of the material used. For example, when Pt was used as the functional layer 322, a substantially good state was obtained. Further, when Ti was used as the functional layer 322, no pattern chipping occurred.

  In this way, by controlling the wettability of the upper surface of the mold pattern using the functional layer, generation of pattern defects seen in the silicon mold is suppressed, and a good large-area imprint pattern can be formed with high accuracy. Become. In this case, the base molding material on which the functional layer is provided is not particularly limited, and for example, silicon can be used. For example, when the dimension of the pattern to be transferred is as large as several μm or more, the mechanical strength is not a big problem, so that the use of a functional layer can suppress pattern chipping. If the mold pattern is formed from the silicon carbide described above, both the resistivity and hardness are suitable, and the wettability is good. Etc. However, it goes without saying that by providing a functional layer with higher wettability such as titanium, the occurrence of patterning can be further suppressed and the pattern can be transferred with higher accuracy.

  By the way, the metal thin film used as the functional layer is difficult to be formed on the recesses or the side surfaces of the pattern when the interval between the mold patterns is narrowed. In such a case, a metal layer (thin film) is formed only on the upper surface of the convex portion of the mold pattern. However, the wettability control only needs to be performed on the upper surface of the mold pattern that comes into contact with (abuts on) the surface of the substrate to be transferred. Therefore, even in the above-described case, the yield improvement effect is not affected. In other words, the functional layer may be formed only on the upper surface of the mold pattern. Therefore, the functional layer may be formed before forming the mold pattern, and the mold pattern may be formed together with the formed functional layer. For example, even if the mold pattern is formed after the thin film is deposited on the area where the mold pattern is formed before the mold pattern is formed, the same effect as described above can be obtained. The deposition (formation) of the thin film may be performed before or after the mold pattern is formed.

  Further, in order to improve the adhesion between the functional layer and the upper surface of the mold pattern, there is no problem even if an adhesion reinforcing layer that improves the adhesion is formed between them. For example, when a functional layer made of titanium is provided, the adhesiveness can be improved by providing an adhesive reinforcing layer made of titanium nitride between the upper surface of the mold pattern. The thickness of the adhesion reinforcing layer may be as thin as about 5 to 20 nm.

  Furthermore, the upper surface of the mold pattern or the surface of the functional layer may be oxidized by about 1 to 2 nm. This is because the wettability of water is further improved. If the film thickness is about this, there is no problem if it is about 1 to 2 nm in terms of resistance. For example, a silicon layer having a thickness of about 10 nm is deposited on a silicon carbide mold (mold pattern) by a known sputtering method or the like. Thereafter, when the mold is treated with dilute sulfuric acid for several minutes, a silicon oxide layer having a thickness of about 1.2 nm is formed on the surface of the formed silicon layer. Since silicon oxide has a contact angle with water of about 10 °, it has high wettability, and the adsorbed water is easily diffused uniformly. Note that the layer is not limited to silicon but may be oxidized by forming a layer made of another material.

Hereinafter, it demonstrates in detail using an Example.
[Example 1]
A polycrystalline silicon carbide film having a thickness of about 2 μm is formed on a support substrate made of a silicon carbide sintered body, using a mixed gas of dichlorosilane-acetylene-hydrogen under conditions of a deposition temperature of 900 ° C. and a gas pressure of 500 Pa. did. A 100 nm wide line / space resist pattern was formed on the polycrystalline silicon carbide film using known electron beam lithography. Next, using the formed resist pattern as a mask, the polycrystalline silicon carbide film was etched to a depth of 0.5 μm by chlorine reactive ion etching, and then the resist pattern was removed with oxygen plasma to form a mold. The mold size was divided into 20 mm squares by dicing.

  Next, the mold was pressed against a 3-inch GaAs substrate with a load of 10 kg, and a pulse voltage of 30 V was applied for 2 minutes between the substrate and the mold under the conditions of an atmospheric humidity of 60% and a mold temperature of 23 ° C. As a result, an oxidized region is formed in the shape of the mold pattern on the main surface of the GaAs substrate. After releasing the mold, the GaAs substrate was etched with chlorine plasma using the formed oxidized region as a mask, and a good GaAs pattern with a width of 100 nm was obtained.

[Example 2]
On a silicon substrate doped with arsenic and having a specific resistance of 0.01 Ωcm, a mixed gas of dichlorosilane-acetylene-hydrogen is used, and the film thickness is about 0.5 μm at a deposition temperature of 900 ° C. and a gas pressure of 500 Pa. A polycrystalline silicon carbide film was formed. A resist pattern having a width of 50 to 300 nm was formed on the polycrystalline silicon carbide film by using known electron beam lithography. Next, using the formed resist pattern as a mask, the polycrystalline silicon carbide film was etched to a depth of 0.2 μm by chlorine reactive ion etching, and then the resist pattern was removed with oxygen plasma to form a mold. Next, titanium was laminated by a 10 nm thick sputtering method, and a functional layer made of titanium was formed on the upper surface of the mold pattern of the formed mold. The mold size was divided into 20 mm squares by dicing.

  Next, a 200 mm diameter silicon substrate washed with a buffered hydrofluoric acid solution is pressed against the mold provided with the functional layer with a load of 30 kg to obtain a silicon substrate / substrate under the conditions of atmospheric humidity 65%, mold and substrate temperature 20 ° C. A DC voltage of 20 V was applied between the molds for 10 seconds. The pressing and application and the movement of the mold position were repeated to form 25 oxidized regions on the silicon substrate. After releasing the mold, the silicon substrate was etched with chlorine plasma using the formed oxidized region as a mask, whereby 25 silicon patterns having a good width of 50 to 300 nm were obtained.

[Example 3]
A polycrystalline silicon carbide mold was produced in the same manner as in Example 1. On top of this, a silicon layer having a thickness of about 10 nm was deposited by sputtering, and further immersed in a 10% sulfuric acid aqueous solution for 5 minutes. After this immersion, the mold is washed with water. The mold thus formed was pressed against a 200 mm diameter silicon substrate washed with a buffered hydrofluoric acid solution with a load of 30 kg, and between the silicon substrate and the mold under the conditions of an atmospheric humidity of 65%, a mold and a substrate temperature of 20 ° C. A DC voltage of 20 V was applied for 60 seconds. The pressing and voltage application and the mold position movement were repeated to form 25 oxidized regions on the silicon substrate. After releasing the mold, the silicon substrate was etched with chlorine plasma using the formed oxidized region as a mask, whereby 25 silicon patterns 25 having a good width of 50 to 300 nm were obtained.

It is process drawing for demonstrating the imprint method which concerns on embodiment of this invention. It is explanatory drawing for demonstrating the formation state of the film | membrane of a polycrystalline silicon carbide. It is process drawing for demonstrating the other imprint method which concerns on embodiment of this invention. It is process drawing for demonstrating imprint lithography. It is process drawing for demonstrating the imprint lithography which applies a voltage between a mold and a board | substrate.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Support substrate, 102 ... Silicon carbide film, 105 ... Power supply, 121 ... Mold pattern, 131 ... Silicon substrate (substrate to be processed), 132 ... Oxidized region, 133 ... Pattern, 301 ... Support substrate, 321 ... Mold pattern 322, functional layer, 331, silicon substrate (substrate to be processed), 332, oxidized region, 333, pattern.

Claims (8)

A first step in which a silicon carbide film made of silicon carbide is formed on a support substrate;
A second step of processing the silicon carbide film to form a mold pattern;
The surface of the support substrate on which the mold pattern is formed is pressed against the main surface of the substrate to be processed, and a voltage is applied between them to oxidize the surface of the substrate to be processed with which the mold pattern abuts. And a third step in which the region is formed. The imprint method according to claim 1,
The imprinting method, wherein the silicon carbide film is composed of polycrystalline silicon carbide formed by chemical vapor deposition on the support substrate. The imprint method according to claim 1 or 2,
The imprinting method, wherein the support substrate is composed of a sintered body of silicon carbide powder. The imprint method according to claim 1 or 2,
The imprinting method, wherein the support substrate is made of silicon. A first step in which a mold pattern is formed on a support substrate;
A second step in which a functional layer for controlling wettability of water is formed on the upper surface of the mold pattern;
The surface of the support substrate on which the mold pattern is formed is pressed against the main surface of the substrate to be processed, and a voltage is applied between the surfaces so that the functional layer on the upper surface of the mold pattern is in contact with the substrate. And a third step in which an oxidized region is formed on the surface of the processing substrate. The imprint method according to claim 5.
In the second step, the functional layer is formed from a material having higher wettability than the material constituting the mold pattern, and thereby the wettability of the water is controlled to be increased. Method. The imprint method according to claim 6.
The imprinting method, wherein the functional layer is composed of at least one of titanium, nickel, and cadmium. The imprint method according to claim 5 or 6,
The imprinting method, wherein the functional layer is formed by oxidizing a surface of silicon.

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