JP2016171189A - Surface planarization method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface planarization method using near-field light capable being carried out without using a chlorine gas.SOLUTION: The surface planarization method using near-field light includes steps of: coating a reactive solution 3 on a surface of an object 2 to be planarized on the surface of which a nano-order projection 22 is formed; and irradiating the object 2 to be planarized coated with the reactive solution 3 with light of a wavelength capable of generating near-field light at the projection 22.SELECTED DRAWING: Figure 3

Description

  In the present invention, when performing photolithography, dry etching, or the like, proximity for selectively removing unnecessary nanoscale protrusions made of photoresist or the like remaining on the surface of a substrate such as a silicon wafer for planarization. The present invention relates to a surface flattening method using field light.

  In recent years, with the miniaturization and high integration of semiconductor devices, there is a demand for a technique for manufacturing a highly miniaturized and multilayered thin film structure. As described above, photolithography or dry etching is used as a method for manufacturing a thin film structure having a fine structure and a multilayered structure (see Patent Document 1).

  When wiring of electronic devices and fine structure processing are performed using photolithography, dry etching, etc., generally, a thin layer made of a plurality of different materials such as a photoresist and a metal thin film is formed on a substrate. . Such a substrate and a structure having a thin layer formed on the surface thereof are hereinafter referred to as a substrate structure. As processing of such a substrate structure proceeds, a thin layer made of a different material is removed from the substrate as necessary, and only a necessary pattern is left on the substrate.

  However, when fine dust or the like adheres to the substrate to be processed and the layer unnecessary by this dust is not sufficiently removed, there are several thin layers that should have been removed. There may be a slight remaining on the surface of the substrate as a convex portion of nm size (nano order).

  If dry etching is further performed in order to remove the nano-order convex portions remaining on the substrate in this way, there is a possibility that even the structure portion such as a pattern to be left is etched. This problem is particularly noticeable when the structure to be left is in the nano-order, as is the unnecessary protrusion.

  Therefore, there has been a strong demand for an etching method that can selectively remove only the unnecessary convex portions in the nano order.

  As a method for enabling such etching, Patent Document 2 discloses a surface flattening method using near-field light.

  Conventionally, the surface planarization method using near-field light has been performed by placing an etching object such as a substrate in a chamber into which a chlorine-based gas has been introduced. Then, by irradiating the etching object with light having a wavelength longer than the absorption edge wavelength of the gas molecule of the chlorine-based gas, near-field light is generated on the convex portion of the surface of the etching object, and this near-field light Etching is performed by the chemical reaction of the convex portion by the active species generated by dissociation of the chlorine-based gas.

Japanese Patent Laid-Open No. 08-031827 JP 2009-167030 A

  The conventional surface flattening method using near-field light described above uses a harmful chlorine-based gas. However, if etching using near-field light can be performed without using such a harmful gas, the surface of safety can be improved. More preferable from the viewpoint.

  If the chlorine-based gas is not required, a vacuum apparatus or the like that has been conventionally required when etching using the chlorine-based gas is not required, and the equipment for performing the etching is greatly simplified, which is further preferable.

  Therefore, the present invention has been devised in view of the above-described problems, and provides a surface flattening method using near-field light that can be performed without using a chlorine-based gas. For the purpose.

  In order to solve the above-described problems, the present inventors have invented a surface flattening method using near-field light that is performed without using a chlorine-based gas.

  The surface flattening method according to the first aspect of the present invention is a surface flattening method using near-field light, which reacts with near-field light on the surface of a flattened object having nano-order convex portions formed on the surface. Applying a reactive solution that generates active species, irradiating the smoothing object to which the reactive solution is applied with light having a wavelength capable of generating near-field light on the convex portion, and It is characterized by having.

  The surface flattening method according to a second invention is characterized in that, in the first invention, the reactive solution is a calcium hypochlorite aqueous solution.

  The surface flattening method according to a third invention is characterized in that, in the first invention, the reactive solution is a sodium hypochlorite aqueous solution.

  According to a fourth aspect of the present invention, there is provided the surface flattening method according to the first aspect, wherein the reactive solution is a hydrogen peroxide solution.

  According to a fifth aspect of the present invention, there is provided the surface flattening method according to the first aspect, wherein the reactive solution is a mixture of potassium potassium and iodine solution.

  According to the present invention having the above-described configuration, by using a reactive solution instead of the conventionally used chlorine-based gas, it is possible to use safer and simpler equipment than the conventional surface flattening method using near-field light. The surface of the object to be flattened can be flattened.

It is a schematic diagram which shows the shape of the surface of the planarization target object. It is a schematic structure figure showing composition of a surface flattening device used in order to perform a surface flattening method concerning the present invention. It is a schematic diagram explaining the reaction generate | occur | produced in the local area | region of a convex part. The process of planarizing the board | substrate which has a convex part is shown, (A) is a schematic diagram which shows the board | substrate before planarization, (B) is the board | substrate of the state in which the near field light generate | occur | produced in the convex part and planarization is performed (C) is a schematic diagram which shows the state by which the board | substrate was planarized. It is a graph which compares the etching effect by the surface planarization method based on this invention, and the surface planarization method using the conventional near field light.

  Hereinafter, an embodiment of a surface flattening method by etching using near-field light according to the present invention will be described.

  First, a substrate that is an object to be planarized in the present embodiment will be described. FIG. 1 is a schematic diagram showing the shape of the surface of the object to be flattened.

  The substrate 2 to be surface flattened by the surface flattening method according to the present embodiment is formed of a material such as glass, plastic, silicon wafer, diamond, gallium nitride, etc., as schematically shown in FIG. On the surface 21 of the substrate 2, a nano-order fine protrusion 22 is formed.

  In addition to the surface roughness of the substrate 2 itself, the protrusion 22 may be generated by an unnecessary oxide film, photoresist, metal thin film, or the like remaining after various processing such as etching on the substrate 2. .

  In the surface flattening method using near-field light according to this embodiment, near-field light is generated at unnecessary convex portions 22 and the reactive species that reacts with near-field light at the convex portions 22 to generate active species. By reacting the active species derived from the solution, it is possible to selectively remove only the convex portion 22 without affecting other portions of the substrate 2.

  The surface flattening method according to the present embodiment is performed using a surface flattening apparatus 1 as schematically shown in FIG.

  This surface flattening device 1 is provided between a light source 11 for irradiating light onto a substrate 2, a reflection mirror 12 that reflects light emitted from the light source and guides it to the substrate 2, and between the reflection mirror 12 and the substrate 2. An illumination optical system 13 that can control the shape and deflection direction of light is provided.

  The light source 11 irradiates light having a predetermined wavelength based on control by a driving power source not disclosed. The light source 11 emits light having a wavelength longer than the absorption edge wavelength of the reactive ions contained in the reactive solution 3 and having a wavelength capable of generating near-field light on the convex portion 22 of the substrate 2. Is done. The light source 11 is composed of, for example, a He—Ne laser oscillator or an Ar laser oscillator.

  Note that the near-field light is generated at the convex portion 22 because only the convex portion 22 has a refractive index different from that of the surrounding reactive solution 3.

  The irradiation optical system 13 includes a polarization lens and a focusing lens (not shown). The irradiation optical system 13 can control the beam diameter and the beam shape in accordance with the position, size, range, and the like of the convex portion 22, and can narrow down the light irradiation range.

  The reflection mirror 12 and the illumination optical system 13 are not essential components for executing the surface flattening method according to the present invention, and the configuration of the surface flattening device 1 can be changed as appropriate.

  In this surface flattening device 1, a substrate 2 with a nano-order convex portion 22 formed on the surface, which is a target of surface flattening by the surface flattening device 1, is coated with a reactive solution 3 on the surface. It is mounted in the state.

  The reactive solution 3 is an aqueous solution such as calcium hypochlorite, sodium hypochlorite, hydrogen peroxide, and a mixture of potassium iodide and iodine. The reactive solution 3 may be applied to the substrate 2 as droplets using a dropper or the like, or may be applied using a spray or a brush. Alternatively, the reactive solution 3 may be placed in a predetermined container, and the substrate 2 may be immersed therein.

  Next, the surface flattening method according to this embodiment will be described by taking as an example the case where calcium hypochlorite is used as the reactive solution 3.

FIG. 3 is a schematic diagram for explaining a reaction that occurs in a local region of a convex portion. The calcium hypochlorite solution that is the reactive solution 3 is dropped onto the substrate 2, and the convex portion 22 of the substrate 2 is covered with the reactive solution 3. The reactive solution 3 is in a state in which calcium hypochlorite Ca (ClO) ₂ is dissolved in water and contains two ions, Ca ²⁺ and ClO ⁻ .

  When light is irradiated from the light source 11 in such a state, near-field light is generated around the convex portion 22.

Then, the ClO ^- ions in the calcium hypochlorite solution are excited by the near-field light generated around the convex portion 22, and as a result, chlorine radicals (Cl.) Are generated.

  When the chlorine radicals thus generated react with the molecules forming the convex portions 22, the convex portions 22 of the substrate 2 are flattened as shown in FIG. 4A and 4B show a process of flattening the substrate 2 having the convex portion 22, where FIG. 4A is a schematic diagram showing the substrate 2 before flattening, and FIG. (C) is a schematic diagram which shows the state by which the board | substrate 2 was planarized.

  Near-field light is generated around the convex portion 22, and chlorine radicals are generated by the near-field light and react with the convex portion 22, whereby the molecules constituting the convex portion 22 are gradually detached and flattened.

  Such flattening can also be performed using a hydrogen peroxide solution that generates active species by near-field light, a mixture of potassium potassium and iodine solution, or the like, as in the calcium hypochlorite solution.

  According to the surface flattening method according to the present embodiment described above, by using the reactive solution, the surface flattening can be performed more safely than the conventional surface flattening method using near-field light using a chlorine-based gas. . In addition, since no chlorine-based gas is used, a conventionally required vacuum apparatus or the like is unnecessary, and the equipment for performing etching can be greatly simplified.

  Furthermore, the surface planarization method according to the present embodiment has higher planarization efficiency than the conventional surface planarization by near-field light using a chlorine-based gas.

  FIG. 5 is a graph comparing the etching effects of the surface flattening method according to the present invention and the conventional surface flattening method using near-field light.

  As shown in FIG. 5, the surface flattening using the calcium hypochlorite solution according to the present embodiment has a low surface roughness Ra (nm) compared to the surface flattening using the conventional chlorine-based gas, More efficient surface flattening is realized. Specifically, by using the surface flattening according to the present embodiment, it is possible to perform surface flattening with extremely high efficiency of Ra = 0.10 nm.

  Further, as shown in FIG. 5, even when hydrogen peroxide solution or a mixture of potassium potassium and iodine solution is used, extremely high-efficiency surface planarization with Ra = 0.10 nm can be performed.

  Thus, according to the surface flattening method according to the present invention, the surface flattening can be performed safely and efficiently with simple equipment by using the reactive solution.

DESCRIPTION OF SYMBOLS 1 Surface planarization apparatus 2 Substrate 3 Reactive solution 11 Light source 12 Reflection mirror 13 Irradiation optical system 21 Surface 22 Convex part

Claims (5)

A surface flattening method using near-field light,
A step of applying a reactive solution to the surface of the planarized object having nano-order convex portions formed on the surface;
Irradiating the smoothed object coated with the reactive solution with light having a wavelength capable of generating near-field light on the convex portion;
A surface flattening method characterized by comprising:   2. The surface flattening method according to claim 1, wherein the reactive solution is a calcium hypochlorite aqueous solution.   2. The surface flattening method according to claim 1, wherein the reactive solution is a sodium hypochlorite aqueous solution.   2. The surface flattening method according to claim 1, wherein the reactive solution is a hydrogen peroxide solution.   2. The surface flattening method according to claim 1, wherein the reactive solution is a mixture of potassium iodine and an iodine solution.

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