JP4791653B2 - Fine pattern drawing material, drawing method and fine pattern forming method using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a novel fine pattern drawing material using a light and heat sensitive substance, a drawing method using the same, and a fine pattern forming method.
[0002]
[Prior art]
In the production of electronic and electrical components such as semiconductor integrated circuits and optical disc masters, research on fine pattern drawing methods such as photolithography using vacuum ultraviolet light (VUV), X-rays, etc. has been actively conducted. Using these technologies, a fine pattern with a line width of 0.1 μm or less has been realized and is expected to be put into practical use in several years (see IEEJ Technical Report No. 770, “Development Trends in Advanced Lithography Technology”). ).
[0003]
By the way, currently, a resist pattern for manufacturing electronic and electric parts is formed by irradiating a photosensitive resist film with actinic light through a predetermined mask pattern to form an image and developing it. Since the minimum dimension of the resist pattern is limited by light diffraction, the limit is practically a dimension slightly below the wavelength used. By the way, this diffraction limit depends on the wavelength of the light to be used and the numerical aperture of the lens, and the limit value can be reduced as the wavelength of the shorter wavelength is used and as the aperture of the lens is increased. Increasing the degree of aperture has almost reached the limit in terms of technology, and at present, the use of light having a short wavelength is proceeding in the direction of miniaturizing the resist pattern.
[0004]
For this reason, research has been conducted on a new exposure technique using deep ultraviolet light, laser light, soft X-rays, etc., and miniaturization of about 150 nm in size has become possible using a KrF excimer laser or an ArF excimer laser. In order to obtain a fine resist pattern having a line and space of 20 nm or less and a related peripheral technology such as development of a high-performance light source and improvement of characteristics in optical materials and resist materials, a large-scale apparatus is required. Or a complicated operation using a special material is unavoidable.
[0005]
In addition, since electron beam lithography uses an electron beam, it can process much finer than light and achieves a processing dimension of several nanometers. Since the apparatus must be carried out in the inside, the size of the apparatus is increased, and a high acceleration voltage of several tens of kV is used, so that consideration must be given to safety.
[0006]
In order to overcome the drawbacks of the conventional fine pattern drawing method, various pattern drawing methods have been proposed. For example, a method (Japanese Patent Application No. 8-249493) is proposed in which a chalcogen compound is irradiated with laser light to generate heat and a crystal state difference is generated in the chalcogen compound to draw a pattern. In this method, fine processing is performed using an etching rate due to a difference in crystal state. Although this method allows pattern drawing exceeding the diffraction limit, the difference in etching rate due to the difference in crystal state is extremely small, and the chalcogen compound film is not necessarily uniform. In particular, it is difficult to obtain a fine pattern with good quality by etching the grain boundary portion first. Further, since the chalcogen compound must be used, there is a drawback that it cannot be applied to fine processing of semiconductors and troubles due to deformation of the chalcogen compound cannot be avoided.
[0007]
In addition, a method using a resist material for direct writing by a laser has been proposed. This is a method using a resist made of a substance that absorbs light and generates heat. However, this method only provides a processing dimension of several μm at most, and the processing dimension is small. Then, a problem that the resist material deforms or evaporates due to a rapid rise in heat occurs. Moreover, since a resist material that is sensitive only to heat is used, it cannot be used in combination with a photolithographic method widely used in semiconductor device manufacturing.
Furthermore, since the resist used here absorbs only a specific wavelength and generates heat, it has a disadvantage that only light of a very limited wavelength can be used. In addition, resist materials that are widely used in semiconductor device manufacturing also have a drawback that the usable wavelengths are limited in the same manner as resist materials for direct writing by heat.
[0008]
[Problems to be solved by the invention]
The present invention overcomes the drawbacks of the conventional method, enables fine processing far smaller than the diffraction limit without requiring a large-scale apparatus, and prevents deformation and evaporation of the resist material due to rapid heat rise. An object of the present invention is to provide a fine pattern drawing method and a fine pattern forming method that can expand the range of usable light and can be combined with an existing optical lithography method, and a novel material used therefor It was made as.
[0009]
[Means for Solving the Problems]
As a result of intensive research in order to develop a new method for forming a fine pattern, the inventors of the present invention have a light intensity distribution in the focused light spot, corresponding to this. Utilizing the formation of heat distribution, converting light into heat using a light-absorbing heat substance, and using the generated heat to excite the reaction to the light and the heat-sensitive substance and the existing photolithographic method By combining the above, it was found that a desired fine pattern can be easily formed, and the present invention has been made based on this finding.
[0010]
That is, in the present invention, a light absorption heat conversion layer and a light and heat sensitive resist layer are provided on a substrate, and a heat protection layer is interposed between the light absorption heat conversion layer and the light and heat sensitive resist layer. A fine pattern drawing material, a fine pattern drawing method for drawing by light irradiation using the same, and a pattern drawing by light irradiation using the fine pattern drawing material, followed by further exposure processing and development processing The fine pattern formation method characterized by these is provided.
In the present invention, pattern drawing means drawing a pattern by a reaction in a predetermined region in the light and heat-sensitive resist layer, and pattern formation means development processing on the substrate after pattern drawing. It means that a structure carrying a pattern is formed.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is an explanatory sectional view showing an example of the structure of a fine pattern drawing material of the present invention and the principle of a drawing method using the same. The fine pattern drawing material has a structure in which a light absorption heat conversion layer 3 and a light and heat sensitive material layer 4 are sequentially laminated on a substrate 1 via a substrate protective layer 2. When the fine pattern drawing material having such a structure is irradiated with the laser light 7 through the lens 8, the temperature of the part 5 rises due to the action of the light absorption heat conversion layer 3, and this heat causes light and heat sensitive substances. Part 6 of the layer reacts. In this figure, the laser beam 7 is irradiated from the substrate 1 side, but can be irradiated from the light and heat sensitive material layer 4 side if desired. The substrate protective layer 2 is provided to protect the substrate 1 from the heat generated in the light absorption heat conversion layer 3, but is not particularly required when the substrate itself has heat resistance.
[0012]
Thus, the condensed light is absorbed by the light absorption heat conversion layer 3 and converted into heat. FIG. 2 is a graph showing the light intensity distribution in the spot of the condensed light on the light absorption heat conversion layer 3 at this time, and thus has a Gaussian distribution. Since the light intensity at the center of the spot is strong, the temperature distribution of the light absorption heat conversion layer 3 is also a Gaussian distribution. When a substance that reacts at a predetermined temperature or higher is used as a light and heat sensitive substance, it can selectively react only at the center of the spot by adjusting the light intensity, and thus far exceeds the diffraction limit. Thermal reaction can occur in the region.
Subsequently, this reacted region can be removed by etching, or conversely, other regions can be removed to form a fine pattern.
[0013]
FIG. 3 shows that the light and heat sensitive material layer 4 is provided with a heat protection layer 9 between the light absorption heat conversion layer 3 and the light and heat sensitive material layer 4 in order to prevent the light and heat sensitive material layer 4 from rapidly rising. FIG. 3 is an explanatory cross-sectional view showing an example of a structure in which a cap layer 10 is provided thereon in order to prevent deformation, evaporation, and expansion due to heat. The light absorption heat conversion layer 3 may absorb light and reach several hundred degrees Celsius, and at this time, plays a role of preventing the light and heat sensitive material layer 4 from evaporating or deforming. In this case, depending on the combination of the substrate 1, the light absorption heat conversion layer 3, and the light and heat sensitive material layer 4, only the heat protection layer 9 or only the cap layer 10 can be used. The thickness of the cap layer 10 is usually selected within the range of 5 to 200 nm, but can be made thinner or thicker depending on the processing dimensions and the material of the light and heat sensitive material layer 4.
[0014]
As the substrate 1 in the fine pattern drawing material of the present invention having these structures, it can be arbitrarily selected from those usually used as substrates when manufacturing electronic and electrical parts by lithography. it can. Examples of such materials include inorganic substrates such as silicon, tantalum, aluminum, gallium-arsenic, and glass plates, and plastic substrates such as polypropylene, acrylic resin, polycarbonate, styrene resin, and vinyl chloride resin. In addition, an inorganic substrate such as aluminum, tantalum, or silicon oxide, a glass plate deposited with aluminum or tantalum, or a glass plate coated with a photo-curable resin layer can also be used.
[0015]
Further, as the material of the light and heat sensitive material layer 4, any material may be used as long as the material changes in properties by heating or irradiation with active light and has a performance capable of revealing a pattern by development processing. be able to. Examples of such photoresists include positive and negative photoresists that have been used in the past to produce electronic and electrical parts by lithography, but have recently been developed for forming fine patterns. A chemically amplified photoresist is preferred.
[0016]
This chemically amplified photoresist is generally a photoresist that consists of a resin component that becomes alkali-soluble by the action of acid and an acid-generating component that generates acid when irradiated with radiation. Until now, sensitivity, resolution, and depth of focus characteristics Various compositions have been proposed so as to improve the stability over time and to provide a pattern having a good cross-sectional shape (for example, JP-A-5-346668, JP-A-7-181777, In the fine pattern drawing material of the present invention, see Kaihei 10-97074, JP-A-10-171109, JP-A-10-207069, JP-A-11-15162, JP-A-11-15158). Any of these may be used.
[0017]
In addition, non-chemically amplified photoresists mainly composed of an alkali-soluble novolac resin and a quinonediazide group-containing compound (for example, US Pat. No. 4,377,761, JP-A-62-235449, JP-A-1-142548) JP-A-1-179147), a non-chemically amplified photoresist mainly composed of a nitrogen-containing heterocyclic polymer and a quinonediazide group-containing compound (see, for example, JP-B-1-46862 and JP-A-4-46345) Etc. can also be used.
[0018]
Next, as the material of the light absorption heat conversion layer 3, any material may be used as long as it has a function of absorbing light and converting it into heat. Examples of such a material include a Ge—Sb—Te alloy such as Ge ₂ Sb ₂ Te ₅ used as a recording layer of a DVD-RAM, an Sb metal, an Ag—In—Sb—Te alloy, and Ag. There are alloys such as -In-Sb-Te-V alloys, compounds such as lithium niobate and methylnitroaniline.
[0019]
The thickness of the light and heat sensitive substance layer 4 in the fine pattern drawing material of the present invention is selected in the range of 10 to 1000 nm, preferably 50 to 200 nm. Further, the thickness of the light absorption heat conversion layer 3 is selected in the range of 5 to 300 nm, preferably 10 to 150 nm. Since the thickness of the light absorption heat conversion layer 3 depends on the wavelength and material of light to be used, it is not necessarily limited to this thickness.
[0020]
In the fine pattern drawing material of the present invention, the substrate protective layer 2 can be provided on the surface of the substrate 1 in order to prevent the substrate 1 from being damaged by the heat generated in the light absorption heat conversion layer 3. As a material of the substrate protective layer 2, for example, an inorganic compound such as ZnS · SiO ₂ or an organic compound such as polyimide is used. The thickness of the substrate protective layer 2 is usually selected within the range of 50 to 500 nm. Since the thickness of the substrate protective layer 2 depends on the wavelength and material of the light used, it is not necessarily limited to this thickness.
[0021]
Further, in the fine pattern drawing material of the present invention, in order to prevent the light and the thermosensitive material layer 4 from being damaged by the rapid temperature rise caused by the heat generated during the light irradiation, the heat protective layer is interposed between the two. 9 can be provided. As the material of the thermal protection layer 9, the same material as that of the substrate protection layer 2 can be used. The thickness of the thermal protection layer 9 is selected within the range of 5 to 100 nm, preferably 10 to 50 nm. Since the thickness of the heat protection layer affects the spread of heat, it is desirable to make it thinner than a desired fine dimension.
[0022]
The light-absorbing heat conversion layer 3 in the fine pattern drawing material of the present invention may reach several hundred degrees Celsius and may cause deformation and evaporation of the heat-photoreactor. Therefore, a cap layer 10 is provided to prevent this. Can do. As a material for the cap layer 10, transparent plastic, transparent glass, or the like is used. The thickness of the cap layer 10 is selected within the range of 5 to 200 nm, preferably 10 to 50 nm. However, since the cap layer 10 is removed prior to development, it is not necessarily limited to this thickness. Absent.
[0023]
Next, FIG. 4 is a process diagram showing an example of the fine pattern forming method of the present invention. That is, first, active light 7, for example, laser light, is applied to a fine pattern drawing material in which the substrate 1, the substrate protective layer 2, the light absorption heat conversion layer 3, the heat protective layer 9, the light and the heat sensitive material layer 4 are sequentially laminated. When heat is generated in the part 5 of the light-absorbing heat conversion layer 3 and the reaction is carried out in the part 6 of the light and heat-sensitive material layer 4, this part changes to a substance that is no longer sensitive to light. (A). Then, when another active light such as blue light 7 'is irradiated over the front surface (b), the portion 6' other than 6 reacts and changes to a substance dissolved in the developer (c). Then, only the portion 6 remains and a fine pattern is formed (d). In this case, the active lights 7 and 7 'are not necessarily different from each other, and may be the same if desired.
[0024]
Next, FIG. 5 is a process diagram showing an example of forming a fine pattern having different dimension portions by combining the fine pattern drawing method of the present invention and the existing optical lithography method. In this example, the substrate is a semiconductor substrate typified by silicon, and the substrate also plays a role of light absorption heat conversion. If there is no possibility of contamination from the light absorption heat conversion layer to the semiconductor substrate, a light absorption heat conversion layer may be provided between the semiconductor substrate and the light and heat sensitive material. In semiconductor microfabrication, not all processing is performed at the minimum dimension level. Therefore, it is preferable to perform a portion having a small size by the drawing method of the present invention and a portion having a large size by the photolithography method.
That is, first, an exposure process is performed on the fine pattern drawing material through the mask pattern 11 by a photolithographic method, and the first latent image portion 12 is drawn on the light and heat sensitive material layer 4 by the active light 7 '(a Then, the non-latent image portion 4 'is irradiated with the active light 7 in accordance with the drawing method of the present invention to draw the second latent image portion 13 (b). Finally, when developed, a fine pattern having a pattern 12 'by the photolithography method and a pattern 13' by the drawing method of the present invention is obtained (c).
However, in some cases, after performing the drawing method of the present invention, an optical lithography method can also be performed.
[0025]
FIG. 6 is an explanatory sectional view showing an example in which the entire sample is processed while heating, and a fine pattern comprising the substrate 1, the substrate protective layer 2, the light absorption heat conversion layer 3, and the light and heat sensitive material layer 4. The drawing material is heated by the heater 14 and processed by the laser beam 7 irradiated through the lens 8.
Thus, by processing while heating, the output of the laser beam can be lowered, and therefore a rapid temperature rise can be prevented. As heating temperature in this case, the range of 50-100 degreeC is preferable. This heating may use laser light irradiation instead of the heater.
[0026]
As a light source in the fine pattern drawing method of the present invention, it can be appropriately selected from various active lights used in general fine pattern drawing as needed. Examples of such active light include visible light, deep ultraviolet light, electron beam, i-line, g-line, KrF excimer laser, and ArF excimer laser. In the method of the present invention, the short wavelength active light can be irradiated from the substrate side through the lens and the long wavelength active light can be irradiated from the opposite side. In this case, the light and heat-sensitive material layer are heated by the long wavelength active light, and the chemical change of the light and the thermosensitive material is promoted by a synergistic effect with the short wavelength active light.
[0027]
【Example】
EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
[0028]
Example 1
A polycarbonate disk substrate (thickness 0.6 mm) is used as the substrate 1 in the structure shown in FIG. 1, ZnS.SiO ₂ (thickness 200 nm) is used as the substrate protective layer 2, and Ge ₂ Sb ₂ Te is used as the light absorption heat conversion layer 3. _{Using 5} layers (thickness 15 nm) and a positive photoresist layer (product name “AZ5214-e” manufactured by Clariant, Inc.) having a thickness of 100 nm as the light and heat-sensitive material layer 4, a fine pattern drawing material was prepared. .
Next, this material was placed on a disk and irradiated with laser light having a wavelength of 635 nm from the substrate side. In this case, the numerical aperture of the optical system is 0.6, the wavelength used is 635 nm, and the diffraction limit is 530 nm. Therefore, when the reaction is performed directly with light without using heat, the size is less than this. A fine pattern cannot be drawn.
Next, using an optical disk drive tester, this material was rotated at a linear velocity of 6 m / s, irradiated with laser light having a reduced output of 3 mW for 10 seconds, and developed according to a conventional method.
The result of observing the fine pattern thus obtained with an atomic force microscope is shown in FIG. In this figure, the fine pattern is shown as a white line on the land. The dimensions of this were 140 nm in width and 30 nm in height.
[0029]
Example 2
A light and heat sensitive material layer 4 having a thickness of 50 nm was formed on the single crystal silicon substrate 1 using the same positive photoresist as in Example 1. Subsequently, the same light absorption heat conversion layer 3 as used in Example 1 was laminated thereon to manufacture a fine pattern drawing material.
Next, straight line drawing was performed using the semiconductor laser light 7 by the method shown in FIG. Reference numeral 15 in the figure denotes a mirror.
After the exposure treatment as described above, the light absorption heat conversion layer 3 was peeled off by etching and then developed to obtain a fine pattern.
[0030]
【The invention's effect】
The fine pattern drawing material and fine pattern drawing method of the present invention are based on a completely new principle, and according to this, it is not necessary to use a large-scale apparatus, and fine processing much smaller than the diffraction limit is performed. be able to. Further, there is an advantage that the resist material is not deformed or evaporated due to a rapid heat rise, which has been a disadvantage of the conventional method, and it can be performed in combination with an existing optical lithography method.
[Brief description of the drawings]
FIG. 1 is an explanatory cross-sectional view showing a structural example of a fine pattern drawing material of the present invention.
FIG. 2 is a graph showing a light intensity distribution in a light spot of a light absorption heat conversion layer.
FIG. 3 is a cross-sectional explanatory view showing another structural example of the fine pattern drawing material of the present invention.
FIG. 4 is a process chart of an example of the forming method of the present invention.
FIG. 5 is a process diagram of an example of a pattern forming method of the present invention in combination with an optical lithography method.
FIG. 6 is an explanatory diagram of a drawing method of the present invention performed while heating.
FIG. 7 is an atomic force microscope photograph of a fine pattern obtained in an example.
FIG. 8 is an explanatory diagram of a drawing method of the present invention in which drawing is performed directly using a semiconductor laser.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Substrate 2 Substrate protective layer 3 Light absorption heat conversion layer 4 Light and heat sensitive material layer 4 'Non-latent image part 5 Temperature increase region of light absorption heat conversion layer 6, 6' Reaction region of light and heat sensitive material layer 7, 7 'active light 8 lens 9 thermal protection layer 10 cap layer 11 mask pattern 12 first latent image portion 13 second latent image portion 12', 13 'pattern 14 heater 15 mirror

Claims (6)

A fine pattern drawing material in which a light absorption heat conversion layer and a light and heat sensitive resist layer are provided on a substrate, and a heat protective layer is interposed between the light absorption heat conversion layer and the light and heat sensitive resist layer. .   The fine pattern drawing material according to claim 1, wherein the substrate has a substrate protective layer on a surface thereof. Fine pattern writing material according to claim 1 or 2 to light and heat sensitive resist layer formed by providing a cap layer. Using a fine pattern writing material according to any one of claims 1 to 3, the drawing method characterized by drawing by light irradiation. The drawing method according to claim 4, wherein heating is performed simultaneously with light irradiation. 6. A fine pattern forming method, wherein after pattern drawing is performed by the method according to claim 4 or 5 , exposure processing and development processing are further performed.

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