JP2001290015A - Method for manufacturing device such as diffraction optical device and method for manufacturing optical system, projection exposure device, semiconductor device or the like having that diffraction optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a device such as a diffraction optical device having good optical performance and high accuracy by which the optical substrate is prevented from etching due to overetching of a hard mask, and to provide a method for manufacturing an optical system, a projection exposure device, a semiconductor device or the like having the above diffraction optical device. SOLUTION: The method of manufacturing a device having a multilevel step pattern includes a process of forming a hard mask pattern on the substrate by etching and forming the multilevel step pattern by using the obtained pattern as the reference. When the hard mask pattern is formed, an etching stopper layer is formed between the material layer for the hard mask and the substrate and then the material layer is etched.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing an element such as a diffractive optical element and an optical system having the diffractive optical element, a projection exposure apparatus, a method for manufacturing a semiconductor device, and the like. , Photography equipment,
The present invention relates to a method of manufacturing a diffractive optical element to be used in a lighting device or the like.

[0002]

2. Description of the Related Art Conventionally, a diffractive optical element has been used as a spectral element of a spectroscope, and its cross-sectional shape is a so-called sawtooth blazed type. In some cases it can reach up to%. on the other hand,
In recent years, a binary optics (BO) element having a step-like lattice cross-sectional shape has attracted attention as an optical element utilizing diffraction, and a BO element having a step-like periodic structure lattice having a predetermined period has an achromatic effect. Because of this and the aspheric surface effect, there is great hope for the development of new optical systems.

[0003] This BO element greatly exceeds the current cutting limit of a blazed type or the like. However,
By using a photolithography technique which is a semiconductor processing method, high-precision fine processing can be performed to some extent. Generally, in the case of an optical element used in the visible light region, it can be manufactured by a molding method of synthetic resin and glass by molding using a metal mold material, but is applied to light having a short wavelength such as ultraviolet light. For this purpose, usable materials are limited, and finer processing accuracy and higher dimensional accuracy are required. For this reason, a BO element applicable to ultraviolet light or far ultraviolet light needs to be manufactured using a photolithography technique using ultraviolet light for semiconductor processing, dry etching processing, or the like.

Japanese Patent Application No. 10-276481 discloses a method of manufacturing such a diffractive optical element. In the case where a multi-stepped element is formed on a substrate by a plurality of lithography steps, the first lithography step is performed. A technique has been disclosed in which a multi-stepped structure is formed by defining the positions of all steps by a pattern formed by a first mask to be formed to form a multi-stepped element. This technique forms a multi-stepped structure by defining the positions of all steps by the pattern of the first mask, so that line width errors and shape errors of the pattern by the first mask occur. Otherwise, an ideal multi-stepped structure without alignment errors can be formed.

[0005]

However, in the above-described conventional method, in a method of manufacturing a BO element applicable to ultraviolet light or far ultraviolet light, a pattern in a submicron region is etched using a hard mask such as chromium. When forming the pattern of the hard mask, since it is difficult to perform the wet etching from the viewpoint of the line width controllability and the sidewall shape controllability of the pattern when forming the pattern of the hard mask, the pattern formation of the hard mask is performed. It must be performed by dry etching. Also, in order to make the pattern cross-sectional shape of the hard mask rectangular by dry etching, when dry etching the hard mask,
It needs to be over-etched. However, such an over-etching causes the underlying optical substrate to be etched, resulting in an etching depth error in the optical substrate. This causes the optical performance of the diffractive optical element to deteriorate.

Accordingly, the present invention solves the above-mentioned problems in the prior art, and can prevent an optical substrate from being etched by over-etching of a hard mask, and can provide a high-precision diffractive optical element having good optical performance. It is an object of the present invention to provide a method for manufacturing an element such as an optical system, a method for manufacturing an optical system having the diffractive optical element, a projection exposure apparatus, and a semiconductor device.

[0007]

In order to achieve the above object, the present invention provides a method for manufacturing an element such as a diffractive optical element having the following constitutions (1) to (12), and a method for manufacturing the diffractive optical element. An object of the present invention is to provide a method for manufacturing an optical system, a projection exposure apparatus, a semiconductor device and the like having the same. (1) A method for manufacturing an element having a multi-stepped step pattern, comprising the steps of: forming a pattern of a hard mask on a substrate by etching, and forming the multi-stepped step pattern based on the pattern; A step of forming an etching pattern by forming an etching stopper layer between the material layer for the hard mask and the substrate when forming the pattern. (2) In the method of manufacturing a diffractive optical element having a multi-staged stepped pattern on an optical substrate, when forming a pattern comprising a hard mask on the optical substrate by etching, the optical substrate and the hard A method for manufacturing a diffractive optical element, comprising: providing an etching stopper layer between the mask and a mask; etching the pattern; and forming a multi-step pattern based on the pattern. (3) The method of manufacturing a diffractive optical element according to (1) or (2), wherein the etching is dry etching. (4) The method for manufacturing a diffractive optical element according to any one of (1) to (3), wherein the etching stopper layer is formed of a material having a high etching selectivity with a hard mask. (5) The method of manufacturing a diffractive optical element according to any one of (1) to (3), wherein the etching stopper layer is formed of a material having a high etching selectivity with a hard mask or a substrate. Method. (6) The method for manufacturing a diffractive optical element according to any one of (1) to (3), wherein the etching stopper layer is formed of alumina. (7) The method for manufacturing a diffractive optical element according to any one of (1) to (6), wherein the hard mask is formed of a metal such as chromium. (8) The method of manufacturing a diffractive optical element according to any one of (1) to (6), wherein the hard mask has a two-layer structure of a chromium layer and a chromium oxide layer. (9) A diffractive optical element manufactured by the method for manufacturing a diffractive optical element according to any one of the above (2) to (8). (10) An optical system having the diffractive optical element according to (9). (11) A projection exposure apparatus having the optical system according to (10). (12) A method for manufacturing a semiconductor device or the like including an exposure step using the projection exposure apparatus according to (11).

In the above structure, the exposure light for forming a pattern is not limited to light such as ultraviolet light, far ultraviolet light, or vacuum ultraviolet light, but may be an electron beam, an ion beam, X-rays, or any other exposure technology. Oxides such as quartz, fluorides such as calcium fluoride, and other materials such as optical glass may be used as the diffractive optical element substrate. In addition, the method for forming the etching stopper layer according to the above configuration includes a vacuum deposition method, a sputtering method, an ion beam sputtering method, an ion plating method, a CVD method,
Alternatively, another film formation method may be used. In the above configuration, the condition of the etching stopper layer is as follows:
When the hard mask is etched, the etching selectivity with the hard mask is large, and when the etching stopper layer is removed, the etching selectivity with the hard mask and the substrate is large. Although alumina is mentioned as an example, it is not necessarily limited to alumina, and other oxides, nitrides such as fluorides and silicon nitrides, and other materials may be used. Further, in the above configuration, as the material of the hard mask, a metal such as chromium, or a two-layer film of chromium oxide and chromium has been described, but other materials may be used.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an embodiment of the present invention,
By using the above-described configuration, it is possible to prevent the underlying optical substrate from being etched by over-etching of the hard mask, a method of manufacturing a high-precision diffractive optical element having good optical performance, and the diffractive optical element , A method of manufacturing a projection exposure apparatus, a semiconductor device, etc.

[0010]

Embodiments of the present invention will be described below. [Embodiment 1] FIGS. 1 to 3 are sectional views showing the steps of manufacturing the diffractive optical element of Embodiment 1. FIG. In the manufacturing process of this embodiment, first, the quartz substrate 1 shown in FIG.
In the step (b), the alumina film 2 is formed as an etching stopper layer by sputtering, for example, for 100 n.
m. The thickness of the etching stopper layer depends on the material of the etching stopper layer, etching conditions,
An optimal value may be selected according to the substrate material and the like. In the step shown in FIG. 1C, a chromium film having a thickness of 80 nm is formed as a hard mask 3 on the alumina film 2 by, for example, a sputtering method, and a chromium oxide film is further formed on the chromium film to have a patterning resolution of 20 nm. Formed to a thickness of Further, in the step of FIG.
A positive resist is dropped on the hard mask 3 described above, and the resist is made into a thin film of about 1 μm by spin coating, and a baking process is performed to form a resist film 4.

Next, in the step of FIG. 1E, the quartz substrate 1 is mounted on an exposure apparatus (not shown), and a reticle 5 having a desired pattern on the hard mask 3 is used to form a reference periodic pattern. A desired pattern of the resist film 4 is formed by exposing and developing. In the step of FIG. 1F, using the pattern of the resist film 4 as a mask,
For example, the hard mask 3 is etched by a reactive ion etching method. At this time, assuming that the time until the surface of the alumina film 2 located under the hard mask 3 is exposed is 100%, the chrome oxide film and the hard mask pattern made of the chromium film are formed in a rectangular shape in order to make the side wall shape rectangular.
Overetch by 00%. The proportion of over-etching may be appropriately selected depending on the material of the hard mask, etching conditions, and the like. Here, due to the presence of the alumina film 2 serving as an etching stopper layer, when the hard mask 3 is over-etched, the quartz substrate is not etched, so that no etching depth error occurs in the quartz substrate 1. Therefore, a highly accurate diffractive optical element can be manufactured. The cross-sectional shape of the pattern formed of the hard mask 3 becomes rectangular due to the over-etching of the hard mask 3, and the photolithography technique is performed in a self-aligned manner by the pattern of the hard mask 3 as described below.

In the step shown in FIG. 1G, the portion of the alumina film 2 not covered with the hard mask 3 is removed using, for example, an aqueous solution of tetramethylammonium hydroxide to remove the portion of the alumina film 2 not covered with the hard mask 3. The quartz substrate 1 is exposed. Next, in the step of FIG.
Using the pattern formed by the hard mask 3 as a mask, the quartz substrate 1 is
Etching is performed to a depth of m to form a concave portion on the surface of the quartz substrate 1. Thereafter, when the pattern of the resist film 4 on the hard mask 3 is removed by the oxygen ashing method and the stripping solution, the pattern becomes as shown in FIG. In the step of FIG. 1J, a positive resist film 4 is applied on the quartz substrate 1 and the hard mask 3 as in the step of FIG. next,
In the step shown in FIG. 1K, a desired pattern of the resist film 4 is formed using the reticle 6. The alignment accuracy at this time may be a value that is half the pattern line width of the hard mask 3.

Next, in the step shown in FIG. 1 (l), the quartz substrate 1 is etched to a depth of 122 nm by, for example, a reactive ion etching method using the pattern of the hard mask 3 and the pattern of the resist film 4 as a mask. Thereafter, when the pattern of the resist film 4 is removed using, for example, an oxygen ashing method and a stripping solution, the pattern shown in FIG. Subsequently, in the step of FIG. 1 (n), a negative resist film 7 is formed on the quartz substrate 1.

Next, as shown in FIG.
Exposure and development from the back side of the above can leave a pattern of the resist film 7 only in a place where the hard mask 3 is not present. At this time, since the hard mask 3 itself becomes a contact mask for negative resist exposure, completely accurate alignment can be performed. Further, in the step of FIG. 1 (p), after a pattern of the negative resist film 7 is hard baked, a positive resist film 4 is formed on the quartz substrate 1,
In the step of FIG. 2A, exposure using a reticle 8 is performed.
Development is performed to form a desired resist film 4 pattern.

In the step of FIG. 2B, portions of the hard mask 3 which are not covered by the patterns of the resist films 4 and 7 are removed by etching using, for example, a mixed solution of cerium ammonium nitrate, perchloric acid and water. I do. Subsequently, in the step of FIG. 2C, the portion of the alumina film 2 that is not covered with the hard mask 3 is removed by etching with, for example, an aqueous solution of tetraammonium hydroxide similarly to the step of FIG. In the step of FIG. 2D, the quartz substrate 1 is etched to a depth of 122 nm by, for example, a reactive ion etching method using the patterns of the resist films 4 and 7 as a mask. Thereafter, when the patterns formed by the resist films 4 and 7 are removed by the oxygen ashing method and the stripping solution, the pattern becomes as shown in FIG.

In the step of FIG. 2F, a positive resist film 4 is formed on the quartz substrate 1 as in the step of FIG. 1D, and in the step of FIG. Exposure and development are performed using the reticle 9 in the same manner as in the process to form a desired resist film 4 pattern. Then Figure 2
In the step (h), using the pattern of the resist film 4 and the hard mask 3 as a mask, the quartz substrate 1 is etched to a depth of 244 nm by, for example, a reactive ion etching method. Then, when the pattern formed by the resist film 4 is removed by, for example, an oxygen ashing method and a stripping solution, FIG.
As shown in (i).

In the step of FIG. 2 (j), a negative resist film 7 is applied on the quartz substrate 1 in the same manner as in the step of FIG. 1 (n), and in the step of FIG. When exposure and development are performed from the back surface of the quartz substrate 1 in the same manner as in the process, a pattern of the resist film 7 can be left only in a portion where the hard mask 3 is not provided. Thereafter, in the step of FIG. 2 (l), hard baking is performed on the pattern of the negative resist film 7 in the same manner as in the step of FIG.
A positive resist film 4 is applied thereon, and in the step of FIG. 2 (m), exposure and development are performed using a desired reticle 10, thereby forming a pattern of the desired resist film 4. In the step of FIG. 2 (n), the hard mask 3 not covered with the pattern by the resist films 4 and 7 is replaced with, for example, cerium ammonium nitrate, perchloric acid and water in the same manner as in the step of FIG. 1 (f). It is removed by etching using a mixed solution.

Subsequently, in the step of FIG. 2 (o), the portion of the alumina film 2 not covered with the hard mask 3 is removed as shown in FIG.
In the same manner as in (g), it is removed by etching using, for example, an aqueous solution of tetraammonium hydroxide. FIG. 2
In the step (p), the portion of the quartz substrate 1 not covered with the resist films 4 and 7 is etched to a depth of 244 nm by, for example, a reactive ion etching method using the pattern of the resist films 4 and 7 as a mask. Thereafter, when the patterns formed by the resist films 4 and 7 are removed by, for example, an oxygen ashing method and a stripping solution, the result is as shown in FIG. Further, in the step of FIG. 3B, the hard mask 3 is removed by etching using the same mixed solution as in the step of FIG. 1F, and the alumina film 2 is formed by using the same aqueous solution as in the step of FIG. Fig. 3
As shown in (c), the diffractive optical element 11 having the diffractive optical element pattern of the eight-stage structure can be formed on the quartz substrate 1.

[Embodiment 2] In Embodiment 2, a diffractive optical element manufactured by the method of Embodiment 1 is applied to a semiconductor exposure apparatus which is a stepper using an ultraviolet ray such as i-line or KrF as shown in FIG. An example of application will be described. Wavelength λ =
A laser beam emitted from an illumination system 12 having a light source of 248 nm irradiates a reticle 13, and a pattern drawn on the reticle 13 is drawn on a substrate 16 on a stage 15 by an imaging optical system 14 at a reduction ratio of 1/5. I do. The imaging optical system 14 incorporates a diffractive optical element 17 manufactured by the method of the first embodiment in order to reduce chromatic aberration and provide an aspherical effect. The diffractive optical element 17 has a step-like BO structure having a diameter of 120 mm and eight steps.
The BO structure is annularly symmetrical with respect to the center of the diffractive optical element, and the pitch of the annular diffraction pattern decreases from the center of the diffractive optical element toward the periphery. The outermost step-like periodic structure has a width of each step of 0.35 μm and a height of 0.061 μm. As a diffraction grating unit, the pitch of the step-like periodic structure is 2.8 μm, and the height is 0.427.
μm.

FIG. 5 shows a semiconductor chip such as an IC or LSI,
FIG. 3 is a flowchart of a manufacturing process of a semiconductor device such as a liquid crystal panel or a CCD. First, step S1
In step S2, a circuit design of a semiconductor device is performed, and then, in step S2, a mask is created from the circuit pattern designed in step S1 using an EB drawing apparatus or the like. On the other hand, in step S3, a wafer is manufactured using a material such as silicon. Thereafter, in step S4 called a pre-process, the mask is loaded into an exposure apparatus using the mask and wafer prepared in steps S2 and S3, and the mask is transported and chucked by a mask chuck.

Next, the wafer is loaded to detect misalignment, the wafer stage is driven to perform alignment, and exposure is performed when the alignment is matched.
After the exposure is completed, the wafer is stepped to the next shot, and a circuit is formed on the wafer by lithography. Further, in step S5 called a post-process, a semiconductor chip is formed using the wafer manufactured in step S4 through an assembly process such as dicing and bonding and a packaging process such as chip encapsulation. In step S6, inspections such as an operation confirmation test and a durability test are performed on the chipped semiconductor device. The semiconductor device is completed through such a series of steps, and the process proceeds to step S7 to be shipped.

FIG. 6 is a flowchart showing a detailed manufacturing process of the wafer process in step S4 in FIG. First, in step S11, the wafer surface is oxidized. Subsequently, in step S12, an insulating film is formed on the wafer surface by the CVD method, and in step S1
In 3, an electrode is formed by a vapor deposition method. Further, the process proceeds to step S14, in which ions are implanted into the wafer, and subsequently, in step S15, a resist is applied on the wafer. In step S16, the circuit pattern of the mask is printed on the resist on the wafer by the semiconductor exposure apparatus. Step S
At 17, the resist on the wafer exposed in step S16 is developed. Further, in step S18, portions other than the resist image developed in step S17 are etched. Thereafter, in step S19, the unnecessary resist after the etching is removed. Further, by repeating these series of steps, multiple circuit patterns can be formed on the wafer.

If this manufacturing method is used, step S16
In this case, since the wafer surface is irradiated with uniform illumination light having various optical aberrations corrected, it is possible to easily and reliably manufacture a highly integrated semiconductor device which has been conventionally difficult to manufacture.

[0024]

As described above, according to the present invention, when a pattern comprising a hard mask is formed on an optical substrate by etching, an etching stopper layer is provided between the optical substrate and the hard mask. Therefore, by forming a diffractive optical element having a multi-stage stepped pattern, even if over-etching when etching the hard mask, the etching depth error does not occur for the optical substrate, high performance A diffractive optical element can be manufactured.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method for manufacturing a diffractive optical element according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a method for manufacturing a diffractive optical element in Embodiment 1 of the present invention.

FIG. 3 is an explanatory diagram of a method for manufacturing a diffractive optical element in Embodiment 1 of the present invention.

FIG. 4 is a configuration diagram of a semiconductor exposure apparatus according to a second embodiment of the present invention.

FIG. 5 is a flowchart of a semiconductor device manufacturing process according to a second embodiment of the present invention.

FIG. 6 is a flowchart of a wafer process in Embodiment 2 of the present invention.

[Explanation of symbols]

 1: quartz substrate 2: alumina film 3: chromium film 4: positive resist film 5, 6, 8, 9, 10: reticle 7: negative resist film 11, 17: diffractive optical element 12: illumination system 13: reticle 14: connection Image optical system 15: Stage 16: Substrate

Claims (12)

[Claims] 1. A method of manufacturing a device having a multi-stepped pattern, comprising: forming a pattern of a hard mask on a substrate by etching; and forming the multi-stepped pattern based on the pattern. A method for manufacturing a device, comprising: forming an etching stopper layer between a material layer for a hard mask and a substrate when forming a pattern of the hard mask; and performing etching. 2. A method of manufacturing a diffractive optical element having a multi-stage stepped pattern on an optical substrate, the method comprising: forming a pattern formed of a hard mask on the optical substrate by etching; A method for manufacturing a diffractive optical element, characterized in that an etching stopper layer is provided between the hard mask and the pattern, and the pattern is etched to form a multi-step pattern based on the pattern. 3. The method of manufacturing a diffractive optical element according to claim 1, wherein said etching is dry etching. 4. The method for manufacturing a diffractive optical element according to claim 1, wherein said etching stopper layer is formed of a material having a high etching selectivity with respect to a hard mask. . 5. The diffractive optical element according to claim 1, wherein the etching stopper layer is formed of a material having a high etching selectivity with a hard mask or a substrate. Production method. 6. The method for manufacturing a diffractive optical element according to claim 1, wherein said etching stopper layer is formed of alumina. 7. The method for manufacturing a diffractive optical element according to claim 1, wherein said hard mask is formed of a metal such as chromium. 8. The method of manufacturing a diffractive optical element according to claim 1, wherein said hard mask has a two-layer structure of a chromium layer and a chromium oxide layer. 9. A diffractive optical element manufactured by the method for manufacturing a diffractive optical element according to claim 2. Description: 10. An optical system having the diffractive optical element according to claim 9. 11. A projection exposure apparatus having the optical system according to claim 10. 12. A method for manufacturing a semiconductor device or the like including an exposure step using the projection exposure apparatus according to claim 11.