JP2005249947A - Method for forming mask, grating, mask, method for forming pattern, optical element and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a finer pattern in an object to be processed by embossing than the pattern of a die. <P>SOLUTION: The method for forming a mask includes steps of forming a film which can be sheared on a deformable or elastic organic substance layer, pressing a die having a pattern on its surface to the film to shear a part of the film along the boundary of the pattern, releasing the die from the film, and removing the sheared portion in the film. If the pattern in the die is, for example, a line-and-space pattern, both of end lines of a flat and long face in a projecting part act as boundaries of the pattern. That is, if the number of lines in the pattern is X, the number of the boundary lines is 2X, which means 2X of shear traces are left in the film. Therefore, by removing the sheared part and processing the film as a mask, 2X lines are formed in the object. Thus, a finer pattern in the object can be formed by embossing than the pattern of the die. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a mask forming method, a grating (diffraction grating), a mask, a pattern forming method, an optical element, and a semiconductor device. The present invention also relates to an embossing process and a mold used therefor.

  The resist pattern in the semiconductor device manufacturing process is mainly formed using photolithography. Photolithography has improved the resolution by shortening the wavelength of the light source of a reduction projection exposure apparatus (stepper) and coped with miniaturization of semiconductor devices. In the stepper, the shorter the wavelength of the light source, the harder the light passes through the lens, so the glass material used for the lens is limited. That is, it is becoming difficult to realize a stepper in terms of optical materials, and the price of a state-of-the-art stepper is several hundred million yen or more.

Photolithography that requires such an expensive stepper is difficult to apply to the manufacture of a small variety of devices in terms of cost. Therefore, as an alternative to photolithography, an attempt has been made to apply embossing to the manufacture of semiconductor devices since around 1995 (see, for example, Patent Document 1 and Non-Patent Document 1).
That is, as represented by the imprint method, attempts have been made to create submicron-order fine patterns by a method in which a die (die, master) is pressed (pressed) on a workpiece to transfer the shape. ing. In recent years, there have been reports of successful processing of patterns smaller than 100 nm. Since the imprint method does not require a stepper and the manufacturing process is simplified, the manufacturing cost can be reduced. Thus, the imprint method is expected as an excellent method that not only makes semiconductor devices finer but also has a possibility of reducing the cost of semiconductor manufacturing equipment.
JP 2003-77807 A (Section 1-7, FIGS. 1 to 11) SYChou et al., J. Vac. Sci. Technol., B15 (1997) p.2897

In the stamping process, since the shape of the mold is transferred to the workpiece, the pattern size of the workpiece is the same as that of the mold. That is, in order to refine the workpiece in the die pressing process, it is necessary to refine the mold itself. The difficulty of processing the mold increases with miniaturization. The stamping process was inferior to photolithography in this respect.
An object of the present invention is to provide a technique for making a pattern of a workpiece finer than a pattern of a mold in a stamping process.

  The mask forming method according to claim 1 includes the following steps. One is a process of forming a shearable film on a deformable or elastic organic material layer. One is a pressing process in which a mold having a pattern formed on the surface is pressed against the film, so that a part of the film is sheared by the boundary of the pattern and then the mold is separated from the film. One is a selective removal process that removes the sheared portion of the membrane.

The invention of claim 2 is a grating having a film sheared by the method of forming a mask of claim 1, characterized in that “the portion removed in the film is a groove”.
A third aspect of the present invention is a mask formed by the mask forming method of the first aspect, wherein a portion removed from the film is an opening.
A fourth aspect of the present invention is a pattern forming method using the mask of the third aspect, and is characterized by the following points. First, the organic layer is formed on the workpiece. Second, after the selective removal step, a part of the organic material layer and a part of the workpiece are removed using the film as a mask, and then the film and the organic material layer are removed.

  The invention of claim 5 is a pattern forming method using the mask of claim 3 and is characterized by the following points. First, the organic material layer has a property of being cured by irradiation with electromagnetic waves, and is formed on the workpiece. Second, after the selective removing step, there is a step of irradiating an electromagnetic wave using the film as a mask to cure a part of the organic material layer. Third, after removing the uncured portion and the film in the organic layer, the organic layer is removed after removing a part of the workpiece using the organic layer as a mask.

  A pattern forming method according to a sixth aspect includes the following steps. One is the process of forming a shearable film on a deformable or elastic workpiece. One is a pressing process in which a mold having a pattern formed on the surface is pressed against the film, so that a part of the film is sheared by the boundary of the pattern and then the mold is separated from the film. One is a selective removal process that removes the sheared portion of the membrane. One is a step of removing the entire film after removing a part of the workpiece using the film as a mask after the selective removing step.

  A pattern forming method according to a seventh aspect includes the following steps. One is a process of forming a shearable film on a workpiece that is deformable or elastic and is cured by irradiation with electromagnetic waves. One is a pressing process in which a mold having a pattern formed on the surface is pressed against the film, so that a part of the film is sheared by the boundary of the pattern and then the mold is separated from the film. One is a selective removal process that removes the sheared portion of the membrane. One is a step of curing a part of the workpiece by irradiating with electromagnetic waves using the film as a mask after the selective removing step. One is a step of removing the uncured portion and film in the workpiece.

The invention according to an eighth aspect is characterized in that, in the pattern forming method according to any one of the fourth to seventh aspects, “a method of removing a part of the workpiece is etching”.
The pattern forming method according to a ninth aspect includes the following steps. One is a process of forming a shearable film on a workpiece that is deformable or elastic and is denatured by irradiation with electromagnetic waves. One is a pressing process in which a mold having a pattern formed on the surface is pressed against the film, so that a part of the film is sheared by the boundary of the pattern and then the mold is separated from the film. One is a selective removal process that removes the sheared portion of the membrane. One is a process of partially processing the workpiece after irradiating the workpiece with electromagnetic waves using the film as a mask after the selective removal step.

  For the film in the above invention, a material having low mechanical strength, etching resistance, etc. may be used at the portion where the boundary portion of the pattern is pressed. Examples of the material include a metal thin film using chromium. Contrary to such a material, a material having high mechanical strength, etching resistance, etc. may be used in a portion where the boundary portion of the pattern is pressed. One embodiment of the present invention in that case is realized by the following steps.

  One is a process of forming a film having such properties on a work piece that is deformable or elastic. One is a step of increasing the mechanical strength or etching resistance of the portion of the film where the boundary of the pattern is pressed by pressing a mold having a pattern formed on the surface against the film. One is a process of selectively removing the film so that a portion with increased mechanical strength or etching resistance remains after the mold is separated from the film. One is a step of removing the entire film after removing a part of the workpiece using the remaining film as a mask.

  In the above embodiment, a film is formed directly on the workpiece, but an organic layer may be formed between the workpiece and the film. One embodiment of the present invention in that case is realized by the following steps. One is a step of forming a deformable or elastic organic material layer on a workpiece and forming a film having the above properties on the organic material layer. One is a step of increasing the mechanical strength or etching resistance of the portion of the film where the boundary of the pattern is pressed by pressing a mold having a pattern formed on the surface against the film. One is a process of selectively removing the film so that a part with increased mechanical strength or etching resistance remains after the mold is separated from the film. One is a process of removing the entire film and the entire organic layer after selectively removing a part of the organic layer and a part of the workpiece using the remaining film as a mask.

The invention of claim 10 is characterized in that, in the pattern forming method of any one of claims 4 to 9, the following points are provided. First, in the pressing step, the step of pressing the mold and the step of separating the mold from the film are each performed twice or more. Second, the selective removal step removes only the portion of the membrane that has been sheared multiple times.
The invention of claim 11 is the pattern forming method according to any one of claims 4 to 10, wherein the minimum width of the pattern formed on the surface of the workpiece is 10 nm or more and 100 nm or less. To do.

According to a twelfth aspect of the present invention, in the pattern forming method according to any one of the fourth to eleventh aspects, the film thickness is 10 nm or more and 100 nm or less.
An optical element according to a thirteenth aspect is processed by using the pattern forming method according to any one of the fourth to twelfth aspects.
A semiconductor device of claim 14 is processed by using the pattern forming method of claim 4 or claim 5.

  In the present invention, the membrane is partially sheared by pressing the mold. If the pattern of the mold is, for example, a line-and-space, the lines at both ends on the upper surface of the line portion (the flat upper surface of the protruding portion that is elongated) become the boundary portion of the pattern. That is, if there are X lines, there are 2X boundaries, and 2X shearing marks are left on the film. Therefore, if the sheared portion is selectively removed and then processed using the film as a mask, 2X lines can be formed on the workpiece. Thus, according to the present invention, the pattern of the workpiece can be made finer than the pattern of the mold in the stamping process.

  FIG. 1 is a schematic process cross-sectional view showing the principle of the stamping process of the present invention. As shown in FIG. 1A, a thin film layer 12 having good shearing properties is formed on a resist layer 10 (corresponding to the organic material layer described in claims). When the thin film layer 12 is formed as a metal thin film, vapor deposition or sputtering may be used. When forming as an organic thin film, it may be applied by spin coating or spraying, or may be formed as a Langmuir-Blodgett film.

  Further, the mold 14 is formed with a pattern having a rectangular wave (line and space) cross section. The resist layer 10 may be formed of, for example, polymethyl methacrylate (PMMA). Note that a polymer material, plastic, or the like may be used instead of the resist as long as the material can be plastically deformed. Alternatively, a material that does not plastically deform even when the die is pressed at a pressure normally used in the die-pressing process, but has elasticity, and temporarily deforms when the die is pressed may be used (for example, a first described later). 4) HOPG). For the thin film layer 12, for example, a metal thin film such as chromium may be used.

  FIG. 1B shows a state where the mold 14 is pressed against the resist layer 10 through the thin film layer 12 after the processing of FIG. As a result, the pattern of the mold 14 is transferred to the resist layer 10. In addition, the portion of the thin film layer 12 where the boundary of the pattern of the mold 14 is pressed extends thinly (density decreases) while maintaining a continuous state, or is discontinuous by shearing as shown in the figure. It becomes a state. In the following description, the case where the membrane is partially thinned by the boundary of the pattern of the die 14 and the separation (shearing) is referred to as “shearing” in the following description. Note that the thickness of the thin film where the flat portion of the unevenness of the mold 14 is pressed does not change much.

  After the shearing process, the mold 14 is separated from the thin film layer 12. FIG. 1C shows this state. In the drawing, for simplification of description, the resist layer 10 is assumed to be completely plastically deformed and maintain the state in which the pattern of the mold 14 is transferred even after the mold 14 is released. Thereafter, necessary processing may be performed based on the trace of the shearing processing. The present invention is based on the inventor's new knowledge that a fine pattern is formed by embossing using such shearing of a thin film. Embodiments will be described below. In addition, in order to avoid duplication, the same code | symbol is attached | subjected to the same element in each figure, and in each embodiment, the part similar to embodiment mentioned above is demonstrated easily.

<First Embodiment>
2 and 3 are schematic process cross-sectional views showing the main part of the pattern forming method according to the first embodiment of the present invention. Hereinafter, a method for manufacturing a grating using the pattern forming method of the present embodiment will be described with reference to FIGS. This embodiment corresponds to claims 1, 3, 4, 8, and 11 to 14.

  First, a workpiece in which an etching stop layer 20 and a silicon layer 22 are formed on a semiconductor substrate (not shown) is prepared. For example, the etching stop layer 20 may be formed as an interface between the two by mechanically attaching two silicon substrates having different impurity concentrations. In this example, the thickness of the silicon layer 22 is the depth of the grating groove.

  Next, a resist layer 26 made of, for example, PMMA is formed on the silicon layer 22, and a thin film layer 28 is formed on the resist layer 26. The resist layer 26 is preferably a photosensitive resin, and may be a negative type such as PMMA or a positive type such as a novolac resin. The thin film layer 28 here is formed as a metal thin film having a thickness of 30 nm composed of titanium 5 nm / aluminum 20 nm / titanium 5 nm. However, the thin film layer 28 is not limited to this, and may be formed of chromium or the like (the same applies to second to sixth embodiments described later). FIG. 2A shows this state.

  The mold 30 is formed with a line and space periodic pattern. As shown in the figure, the pattern here is a one-dimensional lattice having a trapezoidal cross section. That is, the die 30 has a taper (draft angle), and the dimension within one pitch (180 nm) is formed such that two inclined portions and two flat portions are each 45 nm. With this size, the mold 30 can be formed by conventional photolithography.

  In the present embodiment, the angle of the inclined portion is 60 °. In this case, since cos 60 ° = ½, the thin film layer 28 extends approximately twice in the portion where the inclined portion is pressed. The angle of the inclined portion of the mold 30 is desirably 60 degrees or more. This is because if the inclination angle is too gentle, the thin film layer 28 at the portion where the inclined portion is pressed does not sufficiently extend (the density does not sufficiently decrease), and the portion is selectively removed in a later step. Because it becomes difficult to do.

  Next, the mold 30 is pressed against the resist layer 26 through the thin film layer 28 to transfer the pattern of the mold 30 to the resist layer 26. Thereby, the resist layer 26 and the thin film layer 28 are plastically deformed. At this time, in the thin film layer 28, only the portion where the pattern boundary portion (uneven slope portion) is pressed becomes thin (decrease in density), and the length is about twice as described above. Extend to. The portion where the film thickness is reduced here corresponds to the “sheared portion” described in the claims. FIG. 2B shows this state. In addition, since the die 30 is tapered, the die can be easily removed. Therefore, the pressure and temperature when the die 30 is pressed may be the same as in the conventional die pressing process.

Next, the mold 30 is pulled away from the thin film layer 28. FIG. 2C shows this state. In the following description, the process of pressing the mold and pulling the mold away as in the processes so far is referred to as a pressing process.
Next, the sheared portion of the thin film layer 28 is selectively removed by wet etching (corresponding to the selective removal step recited in the claims). FIG. 3D shows this state. In the thin film layer 28, the film thickness and density are greatly different between the portion where the flat portion of the mold 30 is pressed and the portion where the inclined portion is pressed. Therefore, it is possible to remove only the latter by controlling the time of wet etching. The steps up to here correspond to the “mask forming method” recited in the claims.

  Next, dry etching is performed on the resist layer 26 and the silicon layer 22 in the vertical direction (in the thickness direction of the silicon layer 22 and the resist layer 26) using the thin film layer 28 as a mask. At this time, the resist layer 26 is inclined with respect to the thickness direction of the silicon layer 22 under the opening of the mask (the portion where the thin film layer 28 is removed). Therefore, during the etching, the resist layer 26 has a shape shown in FIG. Thereafter, when the etching further proceeds, the shape shown in FIG. The progress of etching stops when it reaches the etching stop layer 20. Accordingly, the etching finally ends in the shape shown in FIG.

  Next, the thin film layer 28 and the resist layer 26 are all removed. As a result, as shown in FIG. 3H, the silicon layer 22 has a line-and-space shape in which a portion where each boundary portion of the pattern of the mold 30 is pressed is a groove. That is, a grating 36 (corresponding to the optical element and the semiconductor device described in claims) having a pitch twice that of the mold 30 is formed. Thereafter, a known process such as vapor deposition of aluminum may be performed to form a reflective grating.

As described above, the width of the boundary portion (inclined portion) between the line and space, not the width of the line and space constituting one pitch of the mold 30, is substantially equal to the width of the pattern formed on the workpiece. . Therefore, if the thin film is partially sheared by the boundary of the pattern of the mold and this thin film is used as a mask, a pattern finer than the pitch of the mold can be easily formed.
In addition, when forming a metal film as thin as possible, the limit which can be formed uniformly is considered to be about 10 nm. Therefore, although the thin film layer 28 is formed with a thickness of 30 nm in this embodiment, it may be formed with a thickness of 10 nm or more as a guide. In order to facilitate the shearing process of the metal film, the width of the inclined portion of the pattern of the mold needs to be as long as the film thickness. In this case, the pattern formed on the workpiece The minimum width is considered to be about 10 nm.

  The depth of a groove of a stamper (mold master) used for forming a thin groove to be engraved on the surface of an optical disk is, for example, about 100 nm when it becomes fine, and the present invention is very remarkable in the formation of such a fine pattern. Effects can be obtained. If the minimum width of the pattern to be formed is about 100 nm, it is desirable that the film thickness be about the same (100 nm) or less to facilitate shearing. The thickness of the thin film layer 28 described above and the minimum width of the pattern formed on the workpiece are the same in other embodiments described later.

<Second Embodiment>
In the second embodiment, a method of forming a pattern, particularly an isolated line, after designing a mold based on a mathematical theory will be described. This embodiment corresponds to claims 1, 3, 4, 8, 11, 12, and 14.
Fig.4 (a) is a perspective view which shows an example of a type | mold. Here, assuming that the back surface of the mold 40 (the region filled with points in the drawing) is flat, arbitrary points on this surface are represented by coordinates x and y. Then, on the pattern forming surface of the mold 40, the height (how much it protrudes) of a point located in the normal direction from a certain coordinate x, y is defined as φ (x, y). The height φ here may be expressed, for example, using the height of the most recessed portion on the pattern forming surface of the mold 40 as a reference (zero).

  Note that the mold 40 of the present embodiment has the same cross-sectional shape in the y direction as shown in the figure for the sake of simplicity. Therefore, φ (x, y) is a function of only x as shown in FIG. If the square of the gradient of φ (x, y) is defined as P (x, y) as in the following equation, P (x, y) corresponding to φ (x, y) in FIG. ) Is as shown in FIG.

  In the mold, the inclination angle of the boundary portion of the pattern is larger as the portion where P (x, y) is larger. When embossing is performed in the same manner as in the first embodiment, in the thin film layer, the film thickness becomes thinner as the part with the larger inclination angle is pressed. Here, in the step of partially removing the thin film layer (corresponding to the wet etching), it is assumed that the portion having a thickness of less than Hthmin is surely removed and the portion having a thickness of Hthmax or more always remains.

  Further, in order to make the film thickness at a certain position of the thin film layer equal to or less than Hthmin, it is necessary to press a portion of the mold 40 where the square of the gradient P (x, y) is equal to or greater than Pthmax to the position. Further, in order to make the film thickness at a certain position of the thin film layer equal to or greater than Hthmax, it is necessary to press a portion of the mold 40 where the square of the gradient P (x, y) is equal to or less than Pthmin to that position. Accordingly, in the thin film layer, the portion where P (x, y) is pressed about Pthmax or more is reliably removed, and the portion where P (x, y) is pressed about Pthmin or less always remains. .

  Next, consider a case where a thin film layer is partially removed and a workpiece having a flat processed surface is etched using the thin film layer as a mask. If the height of the machined surface after machining is defined as Q (x, y), Q (x, y) is given by a function of P (x, y) and takes only two values. If these two values are Qlow and Qhigh, for example, when P (x, y) is Pthmax or more, Q is always Qlow (corresponding to a line and space groove), and when P is Pthmin or less, Q is It must be Qhigh.

The mold 40 in FIG. 4A has two inclined surfaces with different inclination angles, but as shown in FIG. 4C, the square of the gradient is Pa and is smaller than Pthmin in the smoother one. . On the steep side, the square of the gradient is Pb, which is larger than Pthmax. Accordingly, Q (x, y) in this case is as shown in FIG.
For this reason, when performing die pressing using the die 40 of the present embodiment, the process cross-sectional view is as shown in FIG. 5, for example. FIG. 5A shows an example in which an etching stop layer 42, a silicon layer 44, a resist layer 46, and a thin film layer 48 are stacked in this order, and then the resist layer 46 and the thin film layer 48 are plastically deformed by pressing the mold 40. The state where the mold 40 is released is shown. The material, film thickness, and the like of the resist layer 46 and the thin film layer 48 may be the same as those in the first embodiment.

  FIG. 5B shows a state in which the thin film layer 48 is partially removed by wet etching, for example, based on the trace of the shearing process. Thereafter, the silicon layer 44 and the resist layer 46 are dry-etched, for example, using the removed portion of the thin film layer 48 as an opening of the mask, and then the thin film layer 48 and the resist layer 46 are completely removed. As a result, as shown in FIG. 5C, a semiconductor device having an isolated line (iso) is created.

  Note that if the slope of the pattern of the mold 40 is formed steeper, that is, if the mold 40 having a narrow width between a1 and a2 in the drawing is used, a thinner isolated line can be formed. In this case, sufficient shearing can be performed even if the pressure during pressing is smaller. This is because if the inclination angle of the mold 40 is made steeper, the contact area between the mold 40 and the thin film layer 48 at the start of pressing becomes smaller. Therefore, the present invention provides a very remarkable effect in forming a fine pattern.

  The values of Pthmin and Pthmax are determined depending on the conditions of the process of partially removing the thin film layer (etching method, etc.), the thickness of the thin film layer at the time of formation, and the physical multipliers of the thin film layer and the resist layer (for example, elasticity It may be obtained from the limit or breaking point). Or you may obtain | require by experiment. A mold for creating a desired three-dimensional shape can be designed by using Pthmin and Pthmax thus obtained and the expression (1).

<Third Embodiment>
In the third embodiment, a method of forming an isolated point, that is, a contact hole, will be described using equation (1). This embodiment corresponds to claim 1, claim 3, claim 4, claim 8, claim 10 to claim 12, and claim 14. In the present embodiment, a resist layer 46 and a thin film layer 48 are formed on the workpiece having the etching stop layer 42 and the silicon layer 44 in FIG. Since this structure is the same as that of the second embodiment, the process cross-sectional view is omitted in this embodiment.

  The differences between the present embodiment and the second embodiment are the following two points. First, in this embodiment, the embossing is performed twice. Second, the mold of this embodiment has the same shape as that of the second embodiment but is different only in the inclination angle of the protruding portion. That is, the width between a1 and a2 in FIG. 4 is different from the width between a2 and a3. In the mold of this embodiment, the square of the gentler gradient is Pc, the square of the steep gradient is Pd, and Pc and Pd satisfy the following three expressions.

Pc << Pthmin (2)
Pd <Pthmin (3)
Pd × 2> Pthmax (4)
Hereinafter, the pattern forming method of this embodiment will be described with reference to FIG. In this embodiment, the flat upper surface (thin film layer surface) of the workpiece before the mold is pressed is considered as a two-dimensional coordinate plane, and two directions orthogonal to each other on this plane are the x-axis direction and the y-axis. The direction.

  First, the mold is pressed against the thin film layer 48 so that a mark of an inclined portion is formed along the x-axis direction, and then the mold is released. FIG. 6A is a schematic process top view showing this state. In the figure, the area filled with dots is the area where the gentler slope of the mold is pressed, and the hatched area is the area where the sharper slope is pressed. In the present embodiment, φ ′ (x, y) is how much a certain point on the upper surface of the workpiece before pressing the mold is recessed in the normal direction of the coordinate plane after pressing the mold. Similarly to the equation (1), the square of the gradient of φ ′ (x, y) is defined as P ′ (x, y). After the mold has been pressed only once, φ ′ (x, y) is substantially the same as φ (x, y) in the second embodiment except for the sign. Accordingly, P ′ (x, y) is as shown in FIG. 6B between B1 and B2 in FIG.

  Next, the mold is released after pressing the same mold so that the trace of the inclined portion is orthogonal to the first pressing, that is, the trace of the inclined portion is formed along the y-axis direction. FIG. 6C is a schematic process top view showing this state. In FIG. 6 (c), the area where the gentle slope is pressed only once is shown with dots, the area where the gentle slope is pressed twice is shown with a horizontal line, the steep one A region where the inclined portion is pressed only once is indicated by diagonal lines, a steep inclined portion is indicated by blacking out a region where the inclined portion is pressed twice, and the steep inclined portion and the gentle inclined portion are represented by 1 The area that was pressed one by one is indicated by a vertical line. Further, between C1 and C2 in FIG. 6C, P ′ (x, y) is as shown in FIG.

  It is considered that the region where the steep slope portion is pressed twice in the thin film layer 48 is thinner than that after the first pressing and extends to about √2 times the length after the first pressing. Similarly, the region of the thin film layer 48 where the gentler inclined portion is pressed twice is considered to extend to a length approximately √2 times after the first pressing. Since P ′ (x, y) is given by the square of the gradient, it is doubled in a region extending by √2. Accordingly, P ′ (x, y) is as shown in the three-dimensional view of FIG. In FIG. 7, as an example, Pc = 1 and Pd = 6.5 are shown. Further, since Pc and Pd satisfy the above-described expressions (2), (3), and (4), Pthmin is 8 for example and Pthmax is 10 for example in the scale of FIG.

  After the processing shown in FIG. 6C, the thin film layer 48 is partially removed as in the second embodiment. At this time, only the region where the steep inclined portion is pressed twice is removed because P ′ (x, y) is a region equal to or greater than Pthmax. Then, the silicon layer 44 and the resist layer 46 are etched using the thin film layer 48 as a mask in the same manner as in the second embodiment, and then the thin film layer 48 and the resist layer 46 are completely removed. As a result, a contact hole is formed as shown in FIG. As mentioned above, also in 3rd Embodiment, the effect similar to 1st and 2nd embodiment can be acquired.

  In the third embodiment, an example is described in which P ′ (x, y) is equal to or greater than Pthmax only in a region where the mold is pressed twice. The present invention is not limited to such an embodiment. P '(x, y) may be Pthmax or more only in the region where the mold is pressed three times or four times or more. In this case, the pressing process is performed three times or four times or more.

Moreover, the example which presses the same type | mold twice, changing direction was described. The present invention is not limited to such an embodiment. A plurality of dies having different shapes may be prepared, and P ′ (x, y) may be equal to or greater than Pthmax only in a region where each is pressed once or more. In this case, the pressing process is performed once or more for each die.
In addition, an example has been described in which only one protrusion is formed in the mold as a pattern and only one contact hole is formed. The present invention is not limited to such an embodiment. A plurality of protrusions may be provided on the mold as a pattern, and a plurality of contact holes may be formed simultaneously.

<Fourth Embodiment>
In the fourth embodiment, a manufacturing method of a reflective metal grating will be described with reference to a schematic process cross-sectional view shown in FIG. The main feature of the present embodiment is that a portion of the film that is not sheared becomes a part of the element as it is, and an organic material layer that is elastically deformed is formed directly under the film. The present embodiment corresponds to claims 1 to 3 and claims 11 to 13.

  First, as shown in FIG. 8A, a metal thin film 62 is formed on a HOPG (Highly Oriented Pyrolytic Graphite) layer 60. The material and film thickness of the metal thin film 62 may be the same as those in the first embodiment, for example. HOPG has a high elastic limit, and if it has a thickness of several hundred μm or more, its shape can be easily restored even if it is temporarily recessed by about 100 nm by a short (several hundred nm or less) press. Difficulties are known from scanning probe microscope experiments.

  Next, the mold 30 is pressed against the HOPG layer 60 through the metal thin film 62. Thereby, the pattern of the mold 30 is temporarily transferred to the HOPG layer 60, and the metal thin film 62 is partially sheared as in the first embodiment. FIG. 8B shows this state. Thereafter, when the mold 30 is released, the surface of the HOPG layer 60 returns to the original flat shape. FIG. 8C shows this state.

Next, as in the first embodiment, the sheared portion of the metal thin film 62 is removed by etching. As a result, as shown in FIG. 8D, a reflective metal grating 66 having a pitch twice that of the mold 30 is completed. As mentioned above, also in 4th Embodiment, the effect similar to 1st Embodiment can be acquired.
8D, the HOPG layer 60 may be removed by etching using the metal thin films 62 formed at regular intervals as a mask. FIG. 9A is a schematic cross-sectional view of the reflective metal grating formed as described above. The etching depth can be controlled by the etching time and is substantially uniform in each groove. In this embodiment, in order to make the etching depth uniform, the etching stop layer may be formed, the HOPG layer 60 may be formed on the etching stop layer, and then the embossing may be performed. In this case, this embodiment corresponds to claims 1 to 3, claim 6, claim 8, and claims 11 to 13.

  Moreover, in 4th Embodiment, the example which presses the type | mold 30 with the pressure which does not exceed an elastic limit was described. The present invention is not limited to such an embodiment. You may press the type | mold 30 with the pressure exceeding an elastic limit. FIG. 9B is a schematic process cross-sectional view showing a state where the mold 30 is pressed. Thereafter, a cross section when the mold 30 is released is as shown in FIG. The HOPG layer 60 approaches the original flat shape somewhat after the mold 30 is released, but does not completely return to the original shape.

  Thereafter, the metal thin film is partially removed in the same manner as described above, and the HOPG layer 60 is etched using this as a mask. FIG. 9D is a schematic cross-sectional view of the reflective metal grating formed as described above. In this case, this embodiment corresponds to claims 1 to 3, claim 6, claim 8, and claims 11 to 13. Even in this embodiment, the HOPG layer 60 may be formed on the etching stop layer in order to ensure uniform etching depth.

<Fifth Embodiment>
In the fifth embodiment, a workpiece, an ultraviolet curable resin (negative photoresist) layer, and a metal thin film are stacked in this order, and then the workpiece is irradiated with ultraviolet rays using the partially removed metal thin film as a mask. An example of processing is given. This embodiment corresponds to claims 1, 3, 5, 8, 11 to 14. Hereinafter, a pattern forming method according to the fifth embodiment will be described with reference to schematic process cross-sectional views shown in FIGS. 10 and 11.

  First, the etching stop layer 98, the silicon layer 100, the photoresist layer 102, and the metal thin film 104 are laminated in this order. FIG. 10A shows this state. The metal thin film 104 and the mold 30 may be the same as those in the fourth embodiment, and the photoresist layer 102 may be formed using, for example, negative PMMA or Sumitomo Chemical Co., Ltd.'s Smith resist NEK series. Next, after pressing the mold 30 against the photoresist layer 102 through the metal thin film 104, the mold 30 is released. Note that the photoresist layer 102 is plastically deformed. FIG. 10B shows this state.

  Next, as in the first embodiment, after the sheared portion of the metal thin film 104 is removed, ultraviolet rays are irradiated in the vertical direction (in the thickness direction of the metal thin film 104) using the metal thin film 104 as a mask. . Thereby, since the photoresist layer 102 is a negative type, it is cured only under the opening of the metal thin film 104 and becomes insoluble in the stripping solution. FIG. 10C shows this state, and in the figure, the hardened portion is indicated by hatching.

The metal thin film 104 is a film having a total thickness of 30 nm made of, for example, titanium / aluminum / titanium. Even if this is irradiated with, for example, an F ₂ laser (wavelength 157 nm), the transmittance is about 1%. Therefore, even a film made of the same material and thinned to about 10 nm can be sufficiently shielded from light, and the film thickness is not limited to 30 nm.
Next, the entire metal thin film 104 is removed. Thereafter, the uncured portion of the photoresist layer 102 is removed with a stripping solution. FIG. 11D shows this state. Next, the silicon layer 100 is etched using the partially left photoresist layer 102 as a mask. FIG. 11E shows this state. Thereafter, the entire photoresist layer 102 is removed. As a result, the grating 108 is formed as shown in FIG. Thereafter, a known process such as vapor deposition of aluminum may be performed to form a reflective grating.

  Note that since the etching depth when the silicon layer 100 is etched can be controlled by the etching time, the etching stop layer 98 is not necessarily formed. In the first embodiment, the portion below the sheared portion in the thin film layer is formed as a groove, but in this embodiment, the pattern is reversed (the portion below the portion not subjected to shearing is a groove). As described above, also in the fifth embodiment, the same effect as that of the first embodiment can be obtained.

  In the present embodiment, an example in which the negative photoresist layer 102 is formed immediately below the metal thin film 102 has been described. Instead of the negative photoresist layer 102, a deformable positive photoresist layer (for example, Sumitomo Chemical) is used. Sumiresist PEK series manufactured by Kogyo Co., Ltd. may be used). Hereinafter, the pattern forming method in this case will be described with reference to the schematic process cross-sectional view shown in FIG. First, after the etching stop layer 98, the silicon layer 100, the positive photoresist layer 110, and the metal thin film 104 are stacked in this order, the mold 30 is pressed to transfer the pattern of the mold 30 to the positive photoresist layer 110. Is sheared. Thereafter, the mold 30 is released. FIG. 12A shows this state.

  Next, after removing the sheared portion of the metal thin film 104, ultraviolet rays are irradiated in the vertical direction using this as a mask. As a result, the positive photoresist layer 110 is not cured only in the portion that has been irradiated with ultraviolet rays, and becomes soluble in the stripping solution. FIG. 12B shows this state. In the figure, the soluble part is indicated by hatching. Next, after removing the metal thin film 104, the positive photoresist layer 110 is partially removed with a peeling solution. FIG. 12C shows this state. Next, the silicon layer 100 is etched using the partially left positive photoresist layer 110 as a mask. FIG. 12 (d) shows this state. Thereafter, the entire positive photoresist layer 110 is removed. FIG. 12E shows a state in which the grating is formed in this way.

<Sixth Embodiment>
The sixth embodiment is the same as the fifth embodiment except that the metal thin film is formed directly on the workpiece. The present embodiment corresponds to claims 1, 3, 7 to 9, and 11 to 13. Hereinafter, the pattern forming method of the present embodiment will be described with reference to a schematic process cross-sectional view shown in FIG.

  First, a metal thin film 118 is formed on a negative photoresist layer 116 made of, for example, PMMA. FIG. 13A shows this state. The metal thin film 118 and the mold may be the same as those in the fifth embodiment. Next, the mold 30 is pressed against the photoresist layer 116 through the metal thin film 118. As a result, the pattern of the mold 30 is transferred to the photoresist layer 116, and the metal thin film 118 is sheared. Thereafter, the mold 30 is released. FIG. 13B shows this state.

Next, after removing the sheared portion of the metal thin film 118, the metal thin film 118 is used as a mask to irradiate ultraviolet rays in the vertical direction. Thereby, since the photoresist layer 116 is a negative type, only the portion irradiated with the ultraviolet ray is cured and becomes insoluble in the stripping solution. FIG.13 (c) has shown this state, and the hardening part was shown with the oblique line in the figure.
Next, after removing the entire metal thin film 118, the uncured portion of the photoresist layer 116 is removed to a predetermined depth with a stripping solution. The predetermined depth (etching depth) here can be controlled by the etching time and the stripping solution composition, and is substantially uniform in each groove. FIG. 13 (d) shows this state. The photoresist layer 116 processed into such a shape can be used as a grating because the protrusion portion and the groove portion have different refractive indexes. Thereafter, a known process such as vapor deposition of aluminum may be performed to form a reflective grating.

  As described above, in the present embodiment, the lower portion of the shearing portion in the metal thin film is formed as a convex portion, but the same effect as in the fourth embodiment can be obtained. A positive type photoresist (for example, Sumitomo Chemical Co., Ltd. Sumiresist PEK series) which can be deformed and can be cured to become a part of the grating is cured. It may be formed instead of the layer 116. In that case, the pattern to be formed is opposite to that of this embodiment, but the process is the same as that of this embodiment.

<Supplementary items of the present invention>
[1] In the first to third, fifth, and sixth embodiments, the example in which the resist layer that is plastically deformed is formed under the shearable film has been described. The present invention is not limited to such an embodiment. In the first to third embodiments, an organic material layer that is elastically deformed, such as a HOPG layer, may be formed under a shearable film. In the fifth and sixth embodiments, an organic material layer that is cured or uncured by being irradiated with ultraviolet rays and elastically deformed may be formed. Further, the layer formed under the film may be an inorganic layer instead of an organic layer as long as it can be plastically deformed or elastically deformed.

  [2] In the fifth and sixth embodiments, the example in which ultraviolet rays are irradiated has been described. The present invention is not limited to such an embodiment. What is irradiated is not limited to ultraviolet rays, but can be shielded by a film that can be sheared, and if a layer formed immediately below the film (limited to a layer that can be plastically or elastically deformed) can be modified, Other electromagnetic waves may be used. For example, the form which irradiates an electron beam may be sufficient. In this case, an organic material layer that can be plastically deformed or elastically deformed and is cured by being irradiated with an electron beam (for example, Sumitomo Chemical Co., Ltd.'s Sumiresist NEB series) may be used as a photoresist layer (102). Or 116). Then, instead of ultraviolet rays, an electron beam is irradiated to form a pattern having the same shape as in the fifth or sixth embodiment.

  Alternatively, an organic material layer that can be plastically deformed or elastically deformed and softens when irradiated with an electron beam (for example, PMMA or ZEP series manufactured by Zeon Corporation) may be used as a photoresist layer (102 or 116). ) May be formed instead. In this case, an electron beam is irradiated instead of ultraviolet rays to form a pattern having the same shape as in the fifth or sixth embodiment. As described above, the layer that is cured or softened by irradiation with the electron beam is not limited to an organic material, and may be formed of an inorganic material as long as it can be plastically or elastically deformed.

[3] Except for the third embodiment, the example in which the mold is pressed only once has been described. The present invention is not limited to such an embodiment. In all the embodiments described above, the mold may be pressed twice or more in the same manner as described in the third embodiment, and only the portion of the shearable film where the mold is pressed a plurality of times may be removed.
[4] In the first to sixth embodiments, the example in which the sheared portion of the thin film layer is removed and this is used as the contact mask has been described. The present invention is not limited to such an embodiment. The present invention is also applicable to a reflective projection exposure mask, a reduced projection exposure mask, and the like.

  [5] In the first and fifth embodiments, an example of creating a grating formed on a silicon substrate is described. In the fourth and sixth embodiments, an example of creating a grating without using a semiconductor substrate is described. Stated. The present invention is not limited to such an embodiment. The present invention is applicable to the production of other optical elements and other semiconductor devices.

  As described above in detail, the present invention can be greatly used in the fields of masks, pattern forming methods, optical elements, and semiconductor devices.

It is a principle diagram of the present invention. It is typical process sectional drawing which shows the first half process of the pattern formation method of the 1st Embodiment of this invention. It is typical process sectional drawing which shows the latter half process (process after FIG. 2) of the pattern formation method of 1st Embodiment. (A) is a perspective view of the mold according to the second embodiment, (b) is a graph showing the shape of the pattern forming surface of the mold as a function φ (x, y), and (c) is φ (x It is a graph of the square of the gradient of x, y), and (d) is a graph that represents the finally formed pattern as a function Q (x, y). It is typical process sectional drawing which shows the principal part of the pattern formation method of the 2nd Embodiment of this invention. It is a typical process top view showing the important section of the pattern formation method of a 3rd embodiment of the present invention. In 3rd Embodiment, it changes the direction of a type | mold and is a graph which shows P '(x, y) after performing die pressing twice. It is typical process sectional drawing which shows the principal part of the pattern formation method of the 4th Embodiment of this invention. It is a cross-sectional schematic diagram which shows the modification of 4th Embodiment. It is typical process sectional drawing which shows the first half process of the pattern formation method of the 5th Embodiment of this invention. It is typical process sectional drawing which shows the latter half process (process after FIG. 10) of the pattern formation method of 5th Embodiment. In 5th Embodiment, it is typical process sectional drawing in the case of forming a positive type photoresist layer instead of a negative type photoresist layer. It is typical process sectional drawing which shows the principal part of the pattern formation method of the 6th Embodiment of this invention.

Explanation of symbols

10 resist layer 12 thin film layer 14 type 20 etching stop layer 22 silicon layer 26 resist layer 28 thin film layer 30 type 36 grating 40 type 42 etching stop layer 44 silicon layer 46 resist layer 48 thin film layer 60 HOPG layer 62 metal thin film 66 reflective metal Grating 98 Etching stop layer 100 Silicon layer 102 Photoresist layer 104 Metal thin film 108 Grating 110 Positive photoresist layer 116 Photoresist layer 118 Metal thin film

Claims (14)

Forming a shearable film on the deformable or elastic organic layer;
Pressing a mold having a pattern formed on the surface thereof against the film, and after shearing a part of the film by a boundary portion of the pattern, a pressing step of separating the mold from the film;
And a selective removal step of removing a sheared portion of the film.   A grating having a film sheared by the mask forming method according to claim 1, wherein a portion removed in the film is a groove. A mask formed by the method of forming a mask according to claim 1,
The mask is characterized in that the removed portion of the film is used as an opening. A pattern forming method using the mask according to claim 3,
The organic layer is formed on a workpiece,
After the selective removal step, using the film as a mask, removing a part of the organic layer and a part of the workpiece, and then removing the film and the organic layer. Pattern forming method. A pattern forming method using the mask according to claim 3,
The organic layer has a property of being cured by irradiation with electromagnetic waves, and is formed on a workpiece,
After the selective removal step, the step of irradiating an electromagnetic wave using the film as a mask to cure a part of the organic layer;
A step of removing the organic material layer after removing a portion of the organic material layer that has not been cured and the film, and then removing a part of the workpiece using the organic material layer as a mask. A pattern forming method. Forming a shearable film on a deformable or elastic workpiece;
Pressing a mold having a pattern formed on the surface thereof against the film, and after shearing a part of the film by a boundary portion of the pattern, a pressing step of separating the mold from the film;
A selective removal step of removing sheared portions of the membrane;
After the selective removing step, the method includes: removing a part of the workpiece using the film as a mask and then removing the entire film. Forming a shearable film on a work piece that is deformable or elastic and hardens upon irradiation with electromagnetic waves;
Pressing a mold having a pattern formed on the surface thereof against the film, and after shearing a part of the film by a boundary portion of the pattern, a pressing step of separating the mold from the film;
A selective removal step of removing sheared portions of the membrane;
After the selective removal step, a step of irradiating an electromagnetic wave using the film as a mask to cure a part of the workpiece;
A pattern forming method comprising: a part of the workpiece that has not been cured, and a step of removing the film. In the pattern formation method of any one of Claims 4-7,
The pattern forming method, wherein the method for removing a part of the workpiece is etching. Forming a shearable film on a work piece that is deformable or elastic and denatures upon irradiation with electromagnetic waves;
Pressing a mold having a pattern formed on the surface thereof against the film, and after shearing a part of the film by a boundary portion of the pattern, a pressing step of separating the mold from the film;
A selective removal step of removing sheared portions of the membrane;
And a step of partially processing the workpiece after irradiating the workpiece with an electromagnetic wave using the film as a mask after the selective removing step. In the pattern formation method of any one of Claims 4-9,
In the pressing step, the step of pressing the mold and the step of separating the mold from the film are each performed twice or more,
In the selective removal step, only a portion of the film that has been sheared a plurality of times is removed.   11. The pattern forming method according to claim 4, wherein a minimum width of a pattern formed on the surface of the workpiece is 10 nm or more and 100 nm or less.   12. The pattern forming method according to claim 4, wherein the thickness of the film is not less than 10 nm and not more than 100 nm.   An optical element processed by using the pattern forming method according to claim 4.   A semiconductor device processed using the pattern forming method according to claim 4 or 5.

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