JP2010240786A - Workpiece machining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a workpiece machining method capable of simply forming high-precision fine holes, being excellent in machinability in the depth direction and having a high aspect ratio, in a workpiece formed with a heat-mode resist layer. <P>SOLUTION: The workpiece machining method includes at least: a heating step for heating a heat-mode resist layer formed on a substrate; and a fine-hole forming step for forming fine holes by irradiating the heat-mode resist layer in a heated state with a laser beam. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a processing method for a workpiece in which fine holes having a high aspect ratio are formed in a workpiece on which a heat mode resist material is formed.

2. Description of the Related Art Conventionally, a technique for performing fine processing by irradiating a workpiece on which a heat mode resist material is formed with laser light is known.
For example, in a laser processing method for irradiating a processing target made of a heat-reactive substrate with a laser beam and forming a predetermined ultrafine pattern on the surface of the processing target, rotation by rotating the processing target by a rotating means Step, and the laser beam irradiated toward the rotation surface of the workpiece to be rotated by the rotating means, the rotation direction of the workpiece to be irradiated with the laser beam and the irradiation of the laser beam. A moving step for linearly moving in a direction substantially perpendicular to the direction, an irradiating step for emitting the laser light by the irradiating means toward the workpiece, and the laser light from the irradiating means for the objective Forming a beam spot by condensing on the surface of the object to be processed by optical means including a lens, and the beam spot irradiated on the object to be processed. A light detection step of detecting reflected light from the surface of the laser beam by a light detection means, a laser drive step of directly modulating the light intensity of the laser light by a laser drive means, and the light of the beam spot condensed by the optical means An adjustment step of adjusting the intensity distribution by the adjusting means, and the processing object has a predetermined ultrafine pattern not more than the diameter of the beam spot by the beam spot of the light intensity distribution adjusted by the adjusting means. A laser processing method for producing a nanostructure has been proposed (see Patent Document 1).
However, in this case, heat hardly reaches the deep part of the material, resulting in a shallow hole or groove, resulting in a problem that a high aspect ratio is difficult to obtain.

Further, as a method for manufacturing a light emitting element having a light emitter, a recording material layer capable of changing the shape of a heat mode is formed on a light emitting surface, and the recording material layer is irradiated with condensed light, whereby the light emitter Has proposed a method of forming a plurality of recesses at a pitch of 0.01 to 100 times the center wavelength of the light emitted from (see Patent Document 2).
According to this method, fine processing can be performed with high resolution in a processing method capable of forming irregularities by only resist drawing without development.

By the way, in recent years, development of microfabrication technology has been demanded for practical application of nanostructures and application in various technical fields. Particularly, as a high-definition microfabrication technology, in the resist layer, It is important that not only the workability but also the workability in the depth direction is good and a fine hole with a high aspect ratio is obtained.
However, in the conventional method, although the width of the fine hole can be narrowed, the depth is not sufficient, and it is difficult to form the fine hole with a high aspect ratio.

JP 2007-216263 A JP 2008-252056 A

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, the present invention is simple and has a good workability in the depth direction, a high aspect ratio, and a high-definition fine hole can be formed on a workpiece on which a heat mode resist layer is formed. It aims at providing the processing method of a thing.

In order to solve the above-mentioned problems, the present inventor obtained the following knowledge as a result of intensive studies.
In other words, it was expected that when the microhole formation process was performed on the heat mode resist layer in a heated state, the opening diameter of the microhole was expected to expand, but the opening diameter could not be expanded, and it could be processed deeply. The result that a fine hole with a high aspect ratio was obtained was obtained. This result means that a fine hole having a high aspect ratio, which has been conventionally difficult, can be obtained only by a simple method including a heating process for the heat mode resist layer.
The reason why such a result was obtained is not clear, but the temperature at the bottom of the hole has increased and it has become possible to process deeper, and the temperature at the periphery of the hole has increased. It is presumed that the reason why the aspect ratio was increased is that the ejected matter such as fine particles and scattered matter easily reattached.

The present invention is based on the above knowledge, and means for solving the above problems are as follows. That is,
<1> At least a heating step for heating the heat mode resist layer formed on the substrate, and microhole formation for irradiating the heated heat mode resist layer with the laser beam to form microholes And a process for processing the workpiece.
<2> The workpiece processing method according to <1>, wherein the heating is performed by feedback control based on a surface temperature of the substrate detected by a temperature sensor.
<3> When the depth from the outermost surface of the heat mode resist layer is X (nm) and the width at the outermost surface is Y (nm), the aspect ratio X / Y of the formed fine hole is 0. The processing method for a workpiece according to any one of <1> to <2>, wherein the workpiece is 28 to 10.
<4> The method for processing a workpiece according to any one of <1> to <3>, wherein the laser power of the irradiated laser light is 1 mW to 1 W.
<5> The method for processing a workpiece according to any one of <1> to <4>, wherein the surface temperature of the substrate when the laser beam is irradiated is 50 ° C to 500 ° C.
<6> The processing method for a workpiece according to any one of <1> to <5>, wherein the heating is performed using a non-contact heating unit that heats the substrate in a non-contact manner.

  According to the present invention, the conventional problems can be solved, and the object can be achieved. The present invention is simple and can be applied to a workpiece on which a heat mode resist layer is formed. It is possible to provide a method of processing a workpiece that has good workability in the vertical direction, has a high aspect ratio, and can form fine holes with high definition.

FIG. 1 is a schematic view briefly showing the method of processing a workpiece according to the present invention. FIG. 2A is a diagram illustrating an example of a planar view of the surface of the heat mode resist layer in which fine holes are formed. FIG. 2B is a diagram showing another example of a planar view of the surface of the heat mode resist layer in which fine holes are formed. FIG. 3 is a schematic view showing the arrangement of the optical machining head, temperature sensor, and heater used for the machining method of the embodiment with respect to the workpiece.

  The processing method of the workpiece of the present invention includes at least a heating step and a fine hole forming step, and appropriately includes other steps as necessary.

(Heating process)
The heating step is a step of heating the heat mode resist layer formed on the substrate, and is a step of heating the workpiece having the heat mode resist layer formed on the substrate from the substrate side.

-Board-
The substrate is not particularly limited as to the material, shape, structure, size, etc., and can be appropriately selected according to the purpose. Examples of the material include metals, inorganic substances, organic substances, and the like. Examples of the shape include a flat plate shape, and the structure may be a single-layer structure or a laminated structure, and the size may be appropriately selected depending on the application.
The metal is preferably a transition metal. Examples of the transition metal include various metals such as Ni, Cu, Al, Mo, Co, Cr, Ta, Pd, Pt, and Au, or alloys thereof.
Examples of the inorganic material include glass, silicon (Si), and quartz (SiO ₂ ).
Examples of the organic substance include resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), low melting point fluororesin, polymethacrylate methyl (PMMA), and triacetate cellulose (TAC). It is done. Among these, the PET, PC, and TAC are particularly preferable.

-Heat mode resist layer-
The heat mode resist layer is a layer in which light is converted into heat by irradiation of intense light, and the shape of the material can be changed by the heat to form a fine hole (concave portion), and includes a heat mode resist material. Formed with.
The heat mode resist material is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include cyanine-based, phthalocyanine-based, quinone-based, squarylium-based, azurenium-based, thiol complex-based, and merocyanine-based materials. be able to.
Suitable examples include, for example, methine dyes (cyanine dyes, hemicyanine dyes, styryl dyes, oxonol dyes, merocyanine dyes, etc.), macrocyclic dyes (phthalocyanine dyes, naphthalocyanine dyes, porphyrin dyes, etc.), azo dyes (azo metal chelates). Dyes), arylidene dyes, complex dyes, coumarin dyes, azole derivatives, triazine derivatives, 1-aminobutadiene derivatives, cinnamic acid derivatives, quinophthalone dyes, and the like. Among these, methine dyes and azo dyes are particularly preferable.

Note that the heat mode resist layer can appropriately select a dye or modify the structure according to the wavelength of the laser light source.
For example, when the oscillation wavelength of the laser light source is around 780 nm, it is advantageous to select from pentamethine cyanine dye, heptamethine oxonol dye, pentamethine oxonol dye, phthalocyanine dye, naphthalocyanine dye, and the like.
When the oscillation wavelength of the laser light source is around 660 nm, it is advantageous to select from trimethine cyanine dye, pentamethine oxonol dye, azo dye, azo metal complex dye, pyromethene complex dye, and the like.
Further, when the oscillation wavelength of the laser light source is around 405 nm, monomethine cyanine dye, monomethine oxonol dye, zero methine merocyanine dye, phthalocyanine dye, azo dye, azo metal complex dye, porphyrin dye, arylidene dye, complex It is advantageous to select from dyes, coumarin dyes, azole derivatives, triazine derivatives, benzotriazole derivatives, 1-aminobutadiene derivatives, quinophthalone dyes, and the like.

  Hereinafter, examples of a preferable compound as a heat mode resist layer will be given when the oscillation wavelength of the laser light source is around 405 nm. The compounds represented by the following III-1 to III-14 are compounds in the case of around 405 nm. Further, when the oscillation wavelength of the laser light source is around 780 nm, around 660 nm, or preferred around 405 nm, preferable compounds in paragraphs [0024] to [0028] of Japanese Patent Application Laid-Open No. 2008-252056 are listed. The compounds described are mentioned. In addition, this invention is not limited to the case where it uses for these compounds.

<Example of compound when the oscillation wavelength of the laser light source is around 405 nm>

<Example of compound when the oscillation wavelength of the laser light source is around 405 nm>

  JP-A-4-74690, JP-A-8-127174, 11-53758, 11-334204, 11-334205, 11-334206, 11-334207 The dyes described in JP-A No. 2000-43423, JP-A No. 2000-108513, JP-A No. 2000-158818, and the like are also preferably used.

  In such a dye-type heat mode resist layer, a dye is dissolved in a suitable solvent together with a binder and the like to prepare a coating solution, and then this coating solution is applied onto a substrate to form a coating film. Then, it can be formed by drying. In that case, it is preferable that the temperature of the surface which apply | coats a coating liquid is the range of 10-40 degreeC. The lower limit is more preferably 15 ° C. or higher, further preferably 20 ° C. or higher, and particularly preferably 23 ° C. or higher. Moreover, as an upper limit, it is more preferable that it is 35 degrees C or less, It is still more preferable that it is 30 degrees C or less, It is especially preferable that it is 27 degrees C or less. As described above, when the surface temperature to be applied is within the above range, it is possible to prevent the occurrence of coating unevenness and coating failure and make the thickness of the coating film uniform. Each of the upper limit value and the lower limit value can be arbitrarily combined.

Here, the heat mode resist layer may be a single layer or a multilayer. In the case of a multilayer structure, the heat mode resist layer is formed by performing the coating process a plurality of times.
The concentration of the pigment in the coating solution is preferably 0.3% by mass or more and 30% by mass or less, more preferably 1% by mass or more and 20% by mass or less, more preferably tetrafluoro with respect to the organic solvent. It is particularly preferable to dissolve in 1% by mass or more and 20% by mass or less in propanol.

The solvent for the coating solution is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include esters such as butyl acetate, ethyl lactate and cellosolve acetate; ketones such as methyl ethyl ketone, cyclohexanone and methyl isobutyl ketone; dichloromethane Chlorinated hydrocarbons such as 1,2-dichloroethane and chloroform; Amides such as dimethylformamide; Hydrocarbons such as methylcyclohexane; Ethers such as tetrahydrofuran, ethyl ether and dioxane; Ethanol, n-propanol, isopropanol, n-butanol di Alcohols such as acetone alcohol; fluorine-based solvents such as 2,2,3,3-tetrafluoropropanol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol Glycol ethers such as monomethyl ether; and the like. Among these, the butyl acetate, ethyl lactate, cellosolve acetate, methyl ethyl ketone, isopropanol, and 2,2,3,3-tetrafluoropropanol are particularly preferable.
The above solvents can be used alone or in combination of two or more in consideration of the solubility of the dye used. In the coating solution, various additives such as an antioxidant, a UV absorber, a plasticizer, and a lubricant may be added according to the purpose.

Examples of the coating method include a spray method, a spin coat method, a dip method, a roll coat method, a blade coat method, a doctor roll method, a doctor blade method, and a screen printing method. In addition, it is preferable to employ the spin coating method in terms of excellent productivity and easy control of the film thickness.
The heat mode resist material is preferably dissolved in an amount of 0.3% by mass or more and 30% by mass or less, preferably 1% by mass or more and 20% by mass or less with respect to the solvent, from the viewpoint that it is advantageous for formation by a spin coating method. It is more preferable to dissolve by.
Further, the pigment preferably has a thermal decomposition temperature of 150 ° C. or higher and 500 ° C. or lower, and more preferably 200 ° C. or higher and 400 ° C. or lower.
During coating, the temperature of the coating solution is preferably 23 ° C to 50 ° C, more preferably 24 ° C to 40 ° C, and further preferably 25 ° C to 30 ° C.

-Heating-
There is no restriction | limiting in particular as a heating means to perform the said heating, According to the objective, it can select suitably, For example, a hot plate, a cable heater, a cartridge heater, a multicell heater, a thick film heater, a flexible heater, light, RF etc. Non-contact heating means for heating in a non-contact manner by the electromagnetic wave.
When irradiating light while placing the work piece on the spindle and rotating it, if the substrate is heated in advance using contact heating means such as a hot plate, after the rotation, before the rotation servo becomes stable, The substrate temperature may drop to room temperature.
Further, when the substrate is heated by winding the spindle itself with a rubber heater, the temperature of the substrate may not be stabilized by the wind of the rotation of the substrate.
On the other hand, according to the non-contact heating means, the substrate temperature can be heated in a stable state.
From this point of view, the heating means is preferably a non-contact heating means.
Although there is no restriction | limiting in particular as said non-contact heating means, For example, optical lamps, such as an infrared heater and a halogen lamp, are preferable.
There is no restriction | limiting in particular as the temperature of the said heating, Although it can select suitably according to the objective, The surface temperature of the board | substrate at the time of irradiating a laser beam may be heated to the temperature used as 50 to 500 degreeC. Preferably, it is more preferable to heat to a temperature of 60 ° C to 200 ° C and 70 ° C to 130 ° C.
If the temperature is less than 50 ° C., fine holes having a high aspect ratio may not be obtained. If the temperature exceeds 500 ° C., the resist material of the heat mode resist layer may be deteriorated.

The heating method is not particularly limited and may be appropriately selected depending on the intended purpose. However, a heating method is preferable while performing feedback control based on the surface temperature of the substrate detected by the temperature sensor.
The feedback control method is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include PID control and proportional control.
During actual heating, there is a time lag between when the temperature sensor senses and when the heater is turned on and the temperature of the substrate surface is raised. By controlling the temperature or performing PID control in anticipation of the time lag, The time lag can be reduced and the adverse effect of instability of temperature control due to the time lag can be prevented.

As temperature control in the feedback control, for example, when the operating temperature in the heating means is 50 ° C. to 500 ° C., the temperature of the substrate surface is controlled to be 80 ° C. ± 5 ° C. (operating temperature + 8 ° C. ˜15 ° C. or use temperature −2 ° C.).
As a more specific temperature control method, in the case where the operating temperature is 50 ° C. to 500 ° C., the reference temperature of the substrate surface is set to 80 ° C., and the laser irradiation apparatus is set so that the light irradiation angle at 80 ° C. is optimized. Is set in advance. If the temperature sensor detects that the temperature near the surface of the optical recording medium is 70 ° C. during the formation of the fine holes, the heater is turned on to heat the substrate surface to 80 ° C. Thus, the stability of the fine hole forming process is improved by constantly measuring the temperature of the surface of the optical recording medium or in the vicinity of the surface and performing feedback control so that the temperature is maintained at a constant temperature (80 ° C.). Can do.

The temperature sensor is not particularly limited and can be appropriately selected according to the purpose.For example, a non-contact radiation thermometer, a contact thermometer, a thermometer, etc. can be mentioned, but temperature control is performed on the substrate surface. When performed, a non-contact radiation thermometer is preferable because the temperature of the substrate surface itself can be sensed.
Although there is no restriction | limiting in particular as said non-contact radiation thermometer, For example, an infrared thermometer etc. are preferable.

(Micro hole formation process)
The fine hole forming step is a step of forming a fine hole by irradiating the heated heat mode resist layer with a laser beam.
When the heat mode resist layer is irradiated with laser light having a wavelength including the light absorption wavelength of the heat mode resist material (wavelength absorbed by the material), the heat mode resist layer absorbs the laser light and absorbs the laser light. The emitted light is converted into heat, and the temperature of the light irradiated part rises. As a result, the heat mode resist layer undergoes chemical or / and physical changes such as softening, liquefaction, vaporization, sublimation, and decomposition. And the fine hole is formed because the material which caused such a change moves or / and disappears.

-Laser beam-
There is no restriction | limiting in particular as a wavelength of the said laser beam, Although it can select suitably according to the objective, For example, 193 nm, 210 nm, 266 nm, 365 nm, 405 nm, 488 nm, 532 nm, 633 nm, 650 nm, 680 nm, 780 nm, 830 nm For example, 1,000 nm or less is preferable.

There is no restriction | limiting in particular as a kind of said laser beam, According to the objective, it can select suitably, For example, what kind of lasers, such as a gas laser, a solid state laser, a semiconductor laser, may be sufficient. However, in order to simplify the optical system, it is preferable to employ a solid-state laser or a semiconductor laser.
The laser beam may be continuous light or pulsed light, but it is preferable to employ laser light whose emission interval can be freely changed. For example, it is preferable to employ a semiconductor laser. When the laser cannot be directly on / off modulated, it is preferable to modulate with an external modulation element.

In the method for forming a workpiece according to the present invention, since the laser beam is irradiated while the heat mode resist layer is heated by heating through the substrate, the heat mode resist layer is processed. The required laser power can be kept low.
Therefore, it is possible to perform processing at a high processing speed even with a low laser power, and it is possible to reduce the energy cost necessary for laser light irradiation.
Such an upper limit of the laser power is preferably 1 W, more preferably 0.5 W, and particularly preferably 0.1 W. If it exceeds 1 W, it is necessary to scan the heat mode resist layer with laser light at a speed exceeding the upper limit of the scanning speed, which is not practical.
On the other hand, from the viewpoint of reducing energy costs, the laser power is preferably low, and the lower limit of the laser power is preferably 0.01 mW, more preferably 0.1 mW, and particularly preferably 1 mW. If it is less than 0.01 mW, a fine hole with a high aspect ratio may not be obtained. In addition, it is necessary to reduce the scanning speed, and processing time is required.

Further, the laser light is preferably light that has excellent oscillation wavelength width and coherency and can be narrowed down to a spot size equivalent to the wavelength.
In addition, it is preferable to adopt a strategy used in an optical disc as the light pulse irradiation condition for forming a fine hole with a high aspect ratio. That is, it is preferable to employ conditions such as the recording speed, the peak value of the irradiated laser beam, and the pulse width as used in optical disks.

As the thickness of the heat mode resist layer, it is preferable to correspond to the depth of the fine hole described later.
This thickness can be appropriately set within a range of 1 nm to 10,000 nm, for example, and the lower limit of the thickness is preferably 10 nm or more, and more preferably 30 nm or more. If the thickness is too thin, fine holes are formed shallow, and fine holes with a high aspect ratio may not be obtained. Further, the upper limit of the thickness is preferably 1,000 nm or less, and more preferably 500 nm or less. If the thickness is too thick, a large laser power is required, and it may be difficult to form a deep hole, and the processing speed may be reduced.

-Fine hole-
The fine holes formed by the laser light irradiation can be formed with a high aspect ratio.
As the aspect ratio of the fine hole, when the depth from the outermost surface of the heat mode resist layer is X (nm) and the width at the outermost surface is Y (nm), the aspect ratio, X / Y is 0. .28 to 10 is preferable, 0.3 to 5 is more preferable, and 0.35 to 2 is particularly preferable.
The workpiece in which such a fine hole having a high aspect ratio is formed can be applied to various structures that require formation of the fine hole for manufacturing.
The fine hole may have a groove shape. The width Y (nm) in this case indicates the length in the short direction perpendicular to the longitudinal direction of the extended groove.

As the fine holes, it is preferable that a plurality of fine holes are periodically formed in the heat mode resist layer.
As such a formation method, for example, a well-known pit formation method for a write-once optical disc or a write-once optical disc can be applied. Specifically, for example, by detecting the intensity of the reflected light of the laser that changes depending on the pit size, and correcting the output of the laser so that the intensity of the reflected light is constant, a uniform pit is formed. A known running OPC technique (Japanese Patent No. 3096239) can be applied.

  The pitch interval between the plurality of periodically formed fine holes is not particularly limited, but is preferably 10 nm to 100,000 nm from the viewpoint of providing a workpiece in which high-definition fine holes are formed. 50 nm to 10,000 nm are more preferable, and 100 nm to 2,000 nm are particularly preferable.

  Further, the vaporization, sublimation or decomposition of the heat mode resist layer as described above has a large rate of change and is preferably steep. Specifically, the mass reduction rate by differential thermal balance (TG-DTA) at the time of vaporization, sublimation or decomposition of the dye is preferably 5% or more, more preferably 10% or more, and further preferably 20% or more. . Further, the slope of mass decrease by differential thermal balance (TG-DTA) at the time of vaporization, sublimation or decomposition of the pigment (the mass decrease rate per 1 ° C. temperature rise is preferably 0.1% / ° C. or more, and 2% / ° C or more is more preferable, and 0.4% / ° C or more is more preferable.

Further, the transition temperature of chemical or / and physical change such as softening, liquefaction, vaporization, sublimation, and decomposition has an upper limit of preferably 2,000 ° C. or lower, more preferably 1,000 ° C. or lower. It is preferably 500 ° C. or less.
If the transition temperature is too high, a large laser power may be required. Further, the lower limit of the transition temperature is preferably 50 ° C. or higher, more preferably 100 ° C. or higher, and further preferably 150 ° C. or higher. If the transition temperature is too low, the temperature gradient with respect to the surroundings is small, and it may be impossible to form a clear hole edge shape.

(Other processes)
There is no restriction | limiting in particular as said other process, According to the objective, it can select suitably, All the well-known fine processing techniques used for formation processing of a fine hole can be applied as needed.

The processing method of the said workpiece of this invention is demonstrated using figures. FIG. 1 is a schematic view briefly showing the method of processing a workpiece according to the present invention. First, in the processing method of the workpiece, the workpiece 10 having the heat mode resist layer 2 formed on the substrate 1 is heated from the substrate 1 side (heating step).
The heat mode resist layer 2 in a heated state is irradiated with a laser beam condensed through the lens 3 to form the fine hole 4 (fine hole forming step).
Although the reason is not clear, the fine hole 4 formed in this way has good workability in the direction of depth and can be formed with a high aspect ratio.

  FIG. 2A is a diagram of an example of the heat mode resist layer 2 viewed in plan, and FIG. 2B is a diagram of another example of the heat mode resist layer 2 viewed in plan. As shown in FIG. 2A, the fine holes 4 are formed in a substantially dot shape in a plan view, and those in which the dots are arranged in a lattice shape can be adopted. Moreover, as shown to FIG. 2B, the fine hole 4 may be formed in the shape of an elongate groove | channel, and this may connect intermittently. Further, although not shown, it can be formed as a continuous groove shape.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Example 1
Using a 4-inch silicon substrate, 20 mg of an oxonol organic substance (heat mode resist material) represented by the following structural formula (1) is added to 1 mL of 2,2,3,3-tetrafluoro-1-propanol on the silicon substrate. The solution dissolved in 1 was applied at a rotation speed of 300 rpm using a spin coater and then dried at a rotation speed of 1,000 rpm to form a heat mode resist layer having a thickness of 90 nm to prepare a disk-shaped workpiece.

  With respect to this workpiece, a laser beam is emitted from a laser irradiation device (not shown; NEO1000, manufactured by Pulstec Industrial Co., Ltd.) to the workpiece 10 that can rotate in the direction of arrow A in the configuration shown in FIG. The optical processing head 13, the heater 11 (halogen heater; LCB50, manufactured by Infridge Kogyo Co., Ltd.), and the temperature sensor 12 (infrared thermometer; I2-50, manufactured by Keyence Co., Ltd.) were disposed, and fine processing was performed as follows. Note that θ in FIG. 3 was set to 30 °. In FIG. 3, the heat mode resist layer side of the workpiece 10 is F, the substrate side is R, and the content of the heat mode resist layer side (F) is indicated by a chain line.

While the surface temperature of the substrate was detected by the temperature sensor 12, the substrate was heated by the heater 11 under PID feedback control based on the detected value (heating process).
With respect to the heat mode resist layer heated from the substrate side, in a laser irradiation apparatus having the optical processing head 13, under conditions of a linear speed of 5 m / s, a laser power of 6 mW, a frequency of 16.7 MHz, and a duty ratio of 20%, Laser irradiation was performed, and fine holes were formed at a pitch of 300 nm in the circumferential direction (a fine hole forming step). The results are shown in Table 1 below. In addition, the radial position for processing was set at a position 30 mm from the center.

(Comparative Example 1)
In Example 1, the fine hole forming process was performed in the same manner as in Example 1 except that the fine hole forming process was performed without performing the heating process. The results are shown in Table 1 below.

As understood from the comparison between Example 1 and Comparative Example 1, in Example 1, the width of the fine hole was 10 nm wider than that in Comparative Example 1, but the fine hole is formed 20 nm deeper than that. Thus, a fine hole having an aspect ratio higher than that of Comparative Example 1 can be formed and processed.
In addition, the depth (nm) and width (nm) of the fine hole were measured using AFM (OLS3500, manufactured by Olympus).

  Since the processing method of the workpiece of the present invention can form a fine hole with a high aspect ratio in the workpiece, the processing of the fine hole using a heat mode resist material is possible in all technical fields. It can be applied as a processing method for fine holes.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Heat mode resist layer 3 Lens 4 Fine hole 10 Workpiece 11 Heater 12 Temperature sensor 13 Optical processing head P Pitch

Claims (6)

At least a heating step for heating the heat mode resist layer formed on the substrate;
And a fine hole forming step of forming a fine hole by irradiating the heat mode resist layer in the heated state with a laser beam.   The method for processing a workpiece according to claim 1, wherein the heating is performed by feedback control based on a surface temperature of the substrate detected by a temperature sensor.   When the depth from the outermost surface of the heat mode resist layer is X (nm) and the width at the outermost surface is Y (nm), the aspect ratio of the formed fine hole, X / Y is 0.28 to The method for processing a workpiece according to claim 1, wherein the processing method is 10.   The method for processing a workpiece according to any one of claims 1 to 3, wherein the laser power of the irradiated laser light is 1 mW to 1 W.   The method for processing a workpiece according to any one of claims 1 to 4, wherein the surface temperature of the substrate when the laser beam is irradiated is 50 ° C to 500 ° C.   The method for processing a workpiece according to claim 1, wherein the heating is performed using a non-contact heating unit that heats the substrate in a non-contact manner.