JP2006318969A - Method for manufacturing fine structure and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a fine structure that cannot be manufactured by using an aligner. <P>SOLUTION: Resist 2 is applied onto a wafer 1. As the resist 2, resist is used whose γ characteristics are gentle. A mask 3 is used for exposure (a). In this case, the pitch of the image of L/S is close to the resolution limit of a line g stepper, thus setting the shape of the resist 2 to be nearly sinusoidal when the resist 2 is developed (b). A protective film 4 is applied onto the surface of the resist 2, and resist 5 whose γ characteristics are sharp is applied onto the protective film 4 further (c). A mask 6 is used for exposure (d). When the resist 5 is developed, a shape shown in (e) is formed. Their entire thickness is reduced to obtain a shape shown in (f). A wafer 1 is etched with remaining resist as a mask (g). After that, when the resist is dissolved for removal, a fine L/S pattern can be formed on the surface of the wafer (h). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a fine structure on a substrate and a method for producing a semiconductor device using this method.

  As the capacity of semiconductor memories increases, the speed of CPU processors increases, and the capacity increases, the need to increase the degree of integration of semiconductor devices has become even greater. Fine L / S (Line and Space) Developments have been made to form patterns consisting of Conventionally, formation of such a pattern has been performed exclusively using photolithography.

  In photolithography, the line width of a pattern that can be formed is determined by the resolution of the exposure apparatus, and the resolution of the exposure apparatus is determined by the NA of the exposure apparatus, the wavelength used, and the exposure method.

  As described above, the line width of the current L / S pattern is determined by the resolution of the exposure apparatus, and there is a limit to making it finer. The present invention has been made in view of such circumstances, and a method for manufacturing a fine structure that could not be manufactured using the exposure apparatus while using an exposure apparatus having the same resolution as the conventional one, and It is an object of the present invention to provide a semiconductor device manufacturing method using this method.

A first means for solving the above-described problem is a method for manufacturing a microstructure characterized by having the following steps.
(1) A step of forming a first resist layer having a thickness that changes periodically and gradually within one cycle on a substrate.
(2) A step of forming a protective film on the surface of the first resist layer that does not dissolve in the developer that dissolves the second resist layer formed in the next step (3).
(3) A second resist layer having a γ characteristic on the protective film such that a region exposed to a predetermined exposure amount or more is completely dissolved, and a region receiving only a predetermined exposure amount or less is not dissolved. Process for forming a film with uniform thickness
(4) After developing the second resist layer, the second resist layer formed on a region having a thickness greater than or equal to a predetermined thickness of the first resist layer is completely removed, and the first resist layer Exposing the second resist layer with an exposure amount such that the second resist layer formed on a region having a predetermined thickness or less remains.
(5) A step of developing the second resist layer and completely removing the second resist layer formed on the first resist layer on a region having a predetermined thickness or less.
(6) A step of removing the remaining second resist layer and the first resist layer at a constant removal rate.
(7) Etching the substrate using the remaining first resist layer as a mask
(8) Step of removing the remaining first resist layer

  A second means for solving the problem is the first means, wherein the step (1) has a γ characteristic such that the dissolution amount of the resist gradually increases or decreases according to the exposure amount. The first resist layer is a process in which an L / S pattern having a width and a line interval equal to or narrower than the resolution limit of the exposure apparatus is exposed and developed.

  According to a third means for solving the above-mentioned problem, a fine structure is formed on another member by nanoprint technology using a mold manufactured by the fine structure manufacturing method as the first means or the second means. It is a manufacturing method of a fine structure characterized by having a process of transferring.

  A third means for solving the above-described problems includes a step of forming a fine L / S pattern on a wafer as the substrate using the first means or the second means. A method for manufacturing a semiconductor device.

  According to the present invention, while using an exposure apparatus having the same resolution as that of the prior art, a method of manufacturing a fine structure that cannot be manufactured using the exposure apparatus, and manufacturing of a semiconductor device using the method A method can be provided.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an example of manufacturing an L / S pattern having a line width about half the line width that can be manufactured by a conventional exposure apparatus on a wafer by using a conventional exposure apparatus. In this example, a positive resist is used as the resist.

  A g-line (exposure light wavelength: 435.8 nm) stepper is used as an exposure apparatus. A resist 2 is applied on the wafer 1. As this resist 2, a resist having gentle γ characteristics used for manufacturing a microlens using a gray scale mask is used. Then, exposure is performed using a mask 3 such that an L / S image having a pitch (period 600 nm, line width 300 nm) close to the resolution limit determined by the wavelength and numerical aperture of the g-line stepper is formed on the resist 2. (A).

  At this time, since the pitch of the L / S image is close to the resolution limit of the g-line stepper, the L / S pattern on the mask 3 is a binary pattern (complete transmission of light or complete shielding). The image actually formed on 1 has the intensity of a sine wave pattern with a blur and a period of 600 nm. Therefore, when the resist 2 is developed, the γ characteristic of the resist 2 is gentle, so that the shape of the resist 2 is also a sine wave (b). The difference in height between the peaks and valleys of the sine wave is about 20 nm.

  A protective film 4 is applied to the surface of the resist 2, and a resist 5 having sharp γ characteristics is applied thereon (c). The protective film 4 serves as a stopper when the resist 5 is developed later. As long as it does not dissolve in the resist 5 developer, a metal thin film, a self-assembled film, an LB film, a chromic film, an organic dye, Resin can be used. It is necessary that the etching is not highly resistant to etching performed in a later process. Further, the resist 5 is applied with a thin thickness of about 20 nm, so that the resist 5 has a shape having a substantially uniform thickness, which faithfully follows the shapes of the resist 2 and the protective film 4 as the base.

  Subsequently, using the same stepper, exposure is performed using a mask 6 on which an L / S image having a pitch (period 600 nm, line width 300 nm) close to the resolution limit is formed on the resist 2 (d). At this time, a mask 6 in which the pattern of the mask 3 shown in FIG. That is, a portion near the peak of the resist 5 is exposed and a portion near the valley is not exposed.

  Even when the mask 6 is used, the pattern actually formed on the resist 5 becomes a sine wave due to the resolution limit of the stepper as in the case where the mask 3 is used. However, when the resist 5 is developed, the γ characteristic of the resist 5 is sharp, so that the portion that has been exposed to a predetermined exposure amount or more is completely dissolved, and the exposure that is less than the predetermined exposure amount can be received. Since the dissolved amount is small, it remains almost the original pattern, so that the shape shown in (e) is formed. At this time, the protective film 4 is exposed at a portion where the resist 5 is completely dissolved. However, since the protective film 4 is not dissolved in the developing solution of the resist 5, the shape of the resist 2 is kept unchanged.

  Next, when dry etching is performed on the resist 5, the protective film 4, and the resist 2 at the same time under the same etching speed, the etching is performed uniformly at a constant speed from the top (removal of uniform thickness). The shape shown is obtained. If a protective film 4 having an etching rate extremely higher than that of the resist 2 and the resist 5 is used, the thickness of the protective film 4 can be virtually ignored.

  Subsequently, the wafer 1 is etched using the remaining resist 2 as a mask (g), and then the resist 2 is dissolved and removed, whereby an L / S pattern with a period of about 300 nm (line width 150 nm) can be formed on the wafer surface ( h). This is an L / S pattern having about half the size of an L / S pattern that can be produced with the g-line stepper used.

  In this manner, a semiconductor device can be manufactured by forming other logic circuits or the like on the wafer on which the fine line width L / S is formed by the same method as in the prior art. Further, by using the obtained wafer as a mold and performing resin molding by nanoprint technology, a resin having a fine structure on the surface can be produced and used as an optical element such as a diffraction grating.

  In the above description, the resist is assumed to be a positive type. However, a negative type resist can be similarly used by reversing the mask pattern. In the exposure using a stepper, if the wavelength used is λ and the aperture angle of the stepper is NA, the resolution limit is generally determined by λ / NA. However, by performing oblique exposure or shift exposure, λ / (2NA) is known. In the present specification and claims, the “resolution limit” is not the resolution limit unique to the exposure apparatus, but the resolution limit when the exposure method is considered.

  In the above description, in order to make the shape of the resist 2 sinusoidal, a method of exposing a pattern with a pitch about the resolution limit of the stepper and actively using blur is adopted, but the wafer shape is rectangular. If the standing wave of vibration exists on the wafer by exciting from both ends, and the resist is deposited on the wafer in that state, the resist thickness at the antinode of the standing wave of vibration Such a method may be used because the resist 2 having a sinusoidal shape can be formed by reducing the thickness of the resist and increasing the thickness of the resist at the nodes.

It is a figure which shows the example which manufactures the L / S pattern which has a line width of about half of the line width which could be manufactured with the conventional exposure apparatus on the wafer using the conventional exposure apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Wafer, 2 ... Resist, 3 ... Mask, 4 ... Protective film, 5 ... Resist, 6 ... Mask

Claims (4)

The manufacturing method of the microstructure characterized by having the following processes.
(1) A step of forming a first resist layer having a thickness that changes periodically and gradually within one cycle on a substrate.
(2) A step of forming a protective film on the surface of the first resist layer that does not dissolve in the developer that dissolves the second resist layer formed in the next step (3).
(3) A second resist layer having a γ specification on the protective film such that a region exposed to a predetermined exposure amount or more is completely dissolved, and a region receiving only a predetermined exposure amount or less is not dissolved. Process for forming a film with uniform thickness
(4) After developing the second resist layer, the second resist layer formed on a region having a thickness greater than or equal to a predetermined thickness of the first resist layer is completely removed, and the first resist layer Exposing the second resist layer with an exposure amount such that the second resist layer formed on a region having a predetermined thickness or less remains.
(5) A step of developing the second resist layer and completely removing the second resist layer formed on the first resist layer on a region having a predetermined thickness or less.
(6) A step of removing the remaining second resist layer and the first resist layer at a constant removal rate.
(7) Etching the substrate using the remaining first resist layer as a mask
(8) Step of removing the remaining first resist layer 2. The method for manufacturing a microstructure according to claim 1, wherein the step (1) is performed on the first resist layer having γ characteristics such that the dissolution amount of the resist gradually increases or decreases according to the exposure amount. A fine structure manufacturing method, characterized in that it is a step of exposing and developing an L / S pattern having a width and a line interval equal to or smaller than the resolution limit of an exposure apparatus. A method for producing a microstructure comprising a step of transferring a microstructure to another member by a nanoprint technique using a mold produced by the method for producing a microstructure according to claim 1 or 2. . A method for manufacturing a semiconductor device, comprising the step of forming a fine L / S pattern on a wafer as the substrate using the method for manufacturing a microstructure according to claim 1.

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