HK1142965B - Developing method and developing apparatus - Google Patents

Description

Developing method and developing apparatus

Technical Field

The present invention relates to a developing method and a developing apparatus for manufacturing a master optical disc.

Background

For optical discs used for data storage media, various formats including CDs and DVDs have been proposed according to their use. The optical disc substrate employed in each format is typically manufactured by injection molding of a polymer material. On the surface of the substrate, a projection and depression pattern including pits (pit) and grooves is formed.

A projection and depression pattern including pits and grooves formed on an optical disc substrate represents a data signal. By making the projection and depression pattern fine and dense, the capacity of the optical data storage medium can be increased.

By transferring the convex-concave pattern formed on the master optical disc (master optical disc) to the optical disc substrate, the convex-concave pattern including pits and grooves is formed on the optical disc substrate. A master optical disc having a projection and depression pattern thereon can be obtained by forming a resist layer on a substrate and then micromachining the resist layer by photolithography.

In recent years, a high-density optical disc of the blu-ray disc format (registered trademark, hereinafter referred to as "BD") has become very widespread, with a storage capacity of about 25 gbytes in the case of a single-sided single-layer disc, or about 50 gbytes in the case of a single-sided double-layer disc. In order to provide a data capacity of 25 gbytes for a single-sided disc having a diameter of 12cm, it is necessary to reduce the minimum pit length to about 0.17 μm and the track pitch to about 0.32 μm. In order to form a fine projection and depression pattern on a master optical disc used for a high-density optical disc such as a BD, a method of using an inorganic resist instead of an organic resist has been proposed (japanese unexamined patent application publication No. 2003-315988).

When an inorganic resist material made of an incomplete oxide of a transition metal is used as the resist layer, even if exposure is performed with visible laser light having a wavelength of about 405nm, a pattern smaller than the diameter of a spot can be exposed due to the thermal recording property. Therefore, a method using an inorganic resist has been attracting attention as a useful technique for controlling a master optical disc for high-density recording.

The development time of existing lithography with organic resists is only about one minute. In contrast, the development time of photolithography using an inorganic resist ranges from ten to thirty minutes due to a low reaction rate. Therefore, a problem arises in that the pit opening size of the projection and depression pattern varies depending on the development time.

To solve this problem, Japanese unexamined patent application publication No.2006-344310 describes a developing method involving photolithography using an inorganic resist. The developing method is suitable for longer development and allows precise control of development.

The developing method described in japanese unexamined patent application publication No.2006-344310 includes a timing developing method in which a developing time is predetermined and an additional developing method which is additionally performed according to a degree of progress of development. The development is repeatedly performed until the development progresses to a predetermined degree.

With this developing method, a substrate having a resist layer formed thereon (hereinafter referred to as "resist substrate") is developed in a first developing step for a predetermined period of time. Subsequently, in a monitoring step of monitoring the degree of development, the degree of development at a predetermined monitoring position on the resist substrate is measured. In the monitoring step, laser light is incident on a monitoring position on the resist substrate at a predetermined incident angle. The intensity of the zero-order light and the first-order light generated from the projection and depression pattern on the resist substrate was measured using a photosensor. As the photosensitive element, for example, a photodetector may be employed. In the monitoring step, the degree of progress of development can be detected by a light amount ratio (light amount ratio) of the first order light to the zeroth order light, because the intensity of the first order light varies with the size of the pit opening formed by development.

Whether or not additional development is required is determined by the measurement result of the light amount ratio obtained in the monitoring step. If necessary, additional development is performed in the second development step.

However, with a method including timed development and additional development performed as needed (such as the method of japanese unexamined patent application publication No. 2006-344310), it is difficult to perform development stably and accurately because a large number of factors such as sensitivity of the inorganic resist, cutting power, deterioration of the developer, and an environment including temperature and humidity must be optimized.

The monitoring step in japanese unexamined patent application publication No.2006-344310 is performed after the developer on the resist substrate has been removed in the cleaning step and the spin-drying step. That is, the monitoring is performed after the developer is removed from the surface of the resist substrate. Therefore, the degree of progress of development cannot be detected, and accurate control cannot be performed on development for manufacturing a high-density master optical disc such as a BD.

The monitoring position of the monitoring step in japanese unexamined patent application publication No.2006-344310 is set in a recording signal region of the resist substrate at a predetermined distance from the center of the resist substrate, or in a dedicated monitoring signal section performed outside the recording signal region. In order to perform the monitoring, the developer on the monitoring signal portion must be removed by nitrogen (nitrogen blow) and a time-consuming cutting-off step of cutting off the monitoring signal portion must be separately performed, thereby reducing the yield. Also, since the development progress degree at the monitor signal portion is different from that of the signal region, accurate development cannot be performed. Further, it is necessary to prevent nitrogen blowing from affecting the development of the signal area, because nitrogen blowing causes smoke scattering and contaminates the laser light source and photodetector, etc.

Disclosure of Invention

It is desirable to provide a developing method and a developing apparatus for a master optical disc that can be accurately developed.

According to an embodiment of the present invention, there is provided a developing method including the steps of: providing a resist substrate on a rotatable turntable, the resist substrate including a substrate, an inorganic resist layer formed on the substrate, and a latent image formed by exposing the inorganic resist layer; releasing the developer to a developer application position on the upper surface of the inorganic resist layer while rotating the turntable, the developer application position being away from the center of the resist substrate; irradiating a monitoring position on the upper surface of the inorganic resist layer with laser light, the monitoring position being different from a developer coating position; and continuously releasing the developer while detecting the amounts of zeroth order light and first order light of the laser light reflected by the upper surface of the inorganic resist layer, and monitoring the light amount ratio of the first order light to the zeroth order light until the light amount ratio becomes a predetermined value.

In the developing method of this embodiment, the developer application position is away from the center of the resist substrate. Therefore, when the developer is applied to the surface of the resist substrate, the disturbance of the developer liquid surface at the monitoring position, which is different from the developer application position, is reduced. Therefore, the amounts of the zeroth order light and the first order light of the laser light reflected at the monitor position can be stably detected, thereby improving the detection accuracy.

According to an embodiment of the present invention, there is provided a developing apparatus including: a turntable for rotating a resist substrate disposed thereon, the resist substrate including a substrate, an inorganic resist layer formed on the substrate, and a latent image formed by exposing the inorganic resist layer; a nozzle for discharging the developer to a developer application position of the resist substrate placed on the turntable, the developer application position being away from the center of the resist substrate; a laser light source for irradiating a monitoring position on an upper surface of an inorganic resist layer of the resist substrate with laser light, the monitoring position being different from a developer application position; a first sensor for detecting a light amount of zeroth order light of the laser light reflected by the upper surface of the inorganic resist layer; and a second sensor for detecting a light amount of the first order light of the laser light reflected by the upper surface of the inorganic resist layer.

The developing apparatus of this embodiment includes a nozzle that discharges the developer so that the developer is applied to a position of the resist substrate away from the center thereof. Therefore, the developer is released to a developer application position away from the center of the resist substrate, and the developer starts to spread from the developer application position, thereby being applied to the entire surface of the resist substrate. Therefore, the flow rate of the developer is stabilized at the monitoring position different from the developer application position, and the disturbance of the liquid surface of the developer is reduced. Therefore, the amounts of the zeroth order light and the first order light of the laser light reflected at the monitoring position can be stably detected, thereby improving the detection accuracy.

With the embodiments of the present invention, it is possible to develop a resist substrate while monitoring stable detection data, thereby improving the control accuracy of development. Thus, a fine projection and depression pattern can be formed.

Drawings

Fig. 1A to 1C are schematic diagrams (part 1) illustrating steps of manufacturing a master optical disc and an optical disc;

fig. 2D to 2F are schematic diagrams (part 2) illustrating steps of manufacturing a master optical disc and an optical disc;

fig. 3G to 3K are schematic diagrams (part 3) illustrating steps of manufacturing a master optical disc and an optical disc;

fig. 4 is a schematic block diagram of an exposure apparatus for manufacturing a master optical disc and an optical disc;

fig. 5A is a schematic side view and fig. 5B is a schematic plan view of a developing apparatus of the first embodiment of the present invention;

fig. 6 shows a monitoring result of detection obtained by the developing apparatus of the first embodiment;

fig. 7A is a schematic side view of a developing apparatus of a comparative example, and fig. 7B is a schematic plan view of the developing apparatus;

fig. 8 shows a monitoring result of detection obtained by the developing apparatus of the comparative example; and

fig. 9A is a schematic side view of a developing apparatus of a second embodiment of the present invention, and fig. 9B is a schematic plan view of the developing apparatus.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Referring to fig. 1A to 4, examples of methods of manufacturing a master optical disc and an optical disc will be described in order to facilitate understanding of the technology related to the developing method of the embodiment.

As shown in fig. 1A, a substrate 1 having a flat surface is prepared. The substrate 1 is made of glass, silicon, plastic (polycarbonate), or the like. In the embodiment, the substrate 1 is made of silicon. By using the silicon substrate, the front-end step including the cleaning step can be simplified as compared with the case of using a glass substrate or a plastic substrate, so that the number of manufacturing steps can be reduced.

As shown in fig. 1B, an intermediate layer 2 of amorphous silicon is formed on a substrate 1 by vapor deposition such as sputtering. Subsequently, as shown in fig. 1C, an inorganic resist layer 3 is formed on the intermediate layer 2. The thickness of the inorganic resist layer 3 corresponds to the depth of pits and grooves on the master disc. The inorganic resist layer 3 is formed to have a thickness corresponding to a desired depth of the pits and grooves.

The intervening layer 2 is formed to provide a layer having a low thermal conductivity on the substrate 1, thereby optimizing the thermal storage effect.

The inorganic resist layer 3 formed in the step shown in fig. 1C is uniformly formed on the intermediate layer 2 by DC sputtering or RF sputtering. The inorganic resist layer 3 is made of an inorganic resist material. Examples of the inorganic resist material of the inorganic resist layer 3 include Ti, V, Cr, Mn, Fe, Nb, Cu, Ni, Co, Mo, Ta, W, Zr, Ru, and Ag. Mo, W, Cr, Fe or Nb are preferably used. In the examples, Mo and W were used as inorganic resist materials. Sputtering is carried out by using argon (Ar) and oxygen (O)₂) As a sputtering gas. Thus, the inorganic resist layer 3 made of incomplete oxides of W and Mo is formed.

Next, the substrate 1 on which the inorganic resist layer 3 is formed (hereinafter referred to as "resist substrate 8") is set on a turntable of the exposure apparatus shown in fig. 4 with the inorganic resist layer 3 on the upper side. Fig. 4 is a schematic block diagram of an example of the exposure apparatus employed in this embodiment. The exposure apparatus includes: a beam generator 22 that generates laser light that exposes the inorganic resist layer 3; a collimator lens 23 that collimates the laser light emitted from the beam generator 22; a beam splitter 24; and an objective lens 25. The laser light emitted from the beam generator 22 propagates through the lens, and is focused on the inorganic resist layer 3 of the resist substrate 8, so that the inorganic resist layer 3 is irradiated with the laser light. The exposure apparatus is configured such that the reflected light from the resist substrate 8 propagates through the beam splitter 24 and the condenser 26, and the reflected light is focused on a separate photodetector 27. The separated photodetector 27 detects the reflected light from the resist substrate 8, generates a focus error signal 28 based on the result of the detection, and supplies the focus error signal 28 to the focus adjuster 29. The focus adjuster 29 controls the position of the objective lens 25 in the height direction.

The turntable 21 includes a supply mechanism, and the development position of the resist substrate 8 can be changed accurately.

The exposure apparatus performs exposure or focusing, and the laser drive circuit 33 controls the beam generator 22 in accordance with the data signal 30, the reflected light amount signal 31, and the tracking error signal 32. The spindle motor controller 34 is provided on the central axis of the turntable 21. The spindle motor controller 34 controls the spindle motor by setting an optimum rotation speed according to the position of the optical system in the radial direction and the desired linear velocity.

In this embodiment, the wavelength of the laser light emitted by the beam generator 22 is determined according to the desired line width to be exposed. When manufacturing a master disc of a BD, for example, laser light of a short wavelength is preferably emitted. In particular, it is preferred that the beam generator comprises a blue semiconductor laser emitting light having a wavelength of 405 nm.

The beam generator 22 is turned on and off in accordance with the recording signal. The term beam generator 22 "off means that the intensity of the laser light is low enough that the pits are not thermally recorded on the inorganic resist layer 3.

As shown in fig. 2D, in the exposure step, desired positions of the inorganic resist layer 3 are irradiated with laser light L, so that exposed portions 3a and unexposed portions 3b are formed by thermochemical reaction, and a latent image (latent image) for forming pits and grooves is formed on the master optical disc.

After the exposure step, the resist substrate 8 on which the latent image corresponding to the desired projection and depression pattern has been formed is developed by a wet process using an alkali developer. In the developing step, the developing method of the embodiment described below is employed. In the development step, with a developing apparatus described below, the resist substrate 8 is set on a rotatable turntable, and the developer is applied to a desired position of the inorganic resist layer 3 while the resist substrate 8 is rotated, and the exposed portion 3a of the inorganic resist layer 3 is etched.

As the alkali developer, an organic alkali developer such as tetramethylammonium hydroxide solution (tetramethylammonium hydroxide solution) or an inorganic alkali developer such as potassium hydroxide (KOH), sodium hydroxide (NaOH), or a phosphoric acid-based compound may be used.

After the development step, the resist substrate 8 is sufficiently cleaned with pure water. After the cleaning, the resist substrate 8 is rapidly rotated to be dried.

Through the above steps, the master optical disc 9 is manufactured.

As shown in fig. 2F, a metal film 4 is deposited by electroforming (electroforming) on the projection and recess pattern on the upper surface of the master optical disc 9. As necessary, before performing electroforming, mold release treatment (mold release treatment) may be applied to the upper surface of the inorganic resist layer 3 of the master optical disc 9 to improve mold release capability.

In this embodiment, a metallic nickel film is deposited on the convex-concave pattern of the upper surface of the master optical disc 9. After electroforming, the metal film 4 that has been deposited is peeled off from the master optical disc 9. As shown in fig. 3G, a mold stamper (mold stamp) 4a to which the projection and depression pattern of the master optical disc 9 has been transferred is obtained. After obtaining the stamper 4a, the master disc is washed with water, dried and stored. A desired number of model stampers 4a may be replicated repeatedly as required.

By using the stamper 4a peeled off from the master optical disc 9 as a master, an electroforming step and a peeling step can be performed to produce a master (mothermaster) having the same projection and depression pattern as that of the master optical disc. Further, by using the master as a new master, the electroforming step and the peeling step can be performed to produce a stamper having the same projection and depression pattern as that of the stamper master 4 a.

As shown in fig. 3H, a disk substrate 5 made of polycarbonate (which is a thermoplastic resin) is formed by injection molding using a mold stamper 4 a. Thereby, the projection and depression pattern formed on the mold stamper 4a is transferred to the disk substrate 5. As shown in fig. 3I, the mold stamper 4a is peeled off from the disk substrate 5. As shown in fig. 3J, a reflection film 6 made of an aluminum alloy is formed on the projection and depression pattern on the disk substrate 5. As shown in fig. 3K, a protective film 7 is formed to cover the reflective film 6. Thus, the optical disk having a diameter of 12cm was manufactured.

In the above-described development step for manufacturing the master optical disk and the optical disk, by using the developing apparatus and the developing method described below, it is possible to accurately perform development while monitoring the resist substrate.

First embodiment

Fig. 5A is a schematic side view of the developing apparatus used in the developing step (shown in fig. 2D and 2E) of the first embodiment of the present invention. Fig. 5B is a schematic plan view of the developing device. In this first embodiment, the resist substrate 8 to be developed has a latent image constituted by the exposed portions 3a, and the track pitch of the BD is 0.32 μm.

As shown in fig. 5A and 5B, the developing device 15 of the first embodiment includes a rotatable turntable 10 and a nozzle 12 for supplying developer 13. The developing device 15 further includes a laser light source 11 for emitting the monitoring laser light L, a zeroth-order light (reflected light) L for detecting the reflected laser light L₀First sensor R of the amount of light₀And first order light (diffracted light) L for detecting the reflected laser light L₁Second sensor R of the amount of light₁。

The turntable 10 is coupled to a rotation shaft 10a such that the turntable 10 can move up and down. The turntable 10 is rotated by a rotation shaft 10 a. The resist substrate 8 is disposed on the turntable 10 using a vacuum chuck (vacuum chuck) so that the inorganic resist layer 3 is on the upper side. As described above, the inorganic resist layer 3 formed on the substrate 1 has been exposed to light, and a latent image of a projection and depression pattern including pits and grooves is formed thereon. In this first embodiment, the turntable 10 is rotated so that the resist substrate 8 placed thereon is rotated at a rotation speed in the range of 100 to 1000 rpm. In the example shown in fig. 5, the dial 10 rotates clockwise.

The nozzle 12 supplies the developer 13 onto the inorganic resist layer 3 of the resist substrate 8 placed on the turntable 10. The nozzle 12 is disposed above the developer application position P1, the developer application position P1 being away from the center of the resist substrate 8. That is, the nozzle 12 discharges the developer 13 to the developer application position P1 on the surface of the inorganic resist layer 3 away from the center of the resist substrate 8, and the entire surface of the resist substrate 8 is supplied with the developer. In this first embodiment, the nozzle 12 supplies the developer 13 at a flow rate in the range of 300 to 1000 ml/min.

It is preferable that the distance between the developer application position P1 and the center of the resist substrate 8 is in the range of about 20 to 40 mm. If the distance between the developer application position P1 and the center of the resist substrate 8 is less than 20mm, the flow rate of the developer 13 at the monitor position P2 (to be described later) becomes unstable, so that the monitoring at the monitor position P2 cannot be accurately performed. If the distance between the developer application position P1 and the center of the resist substrate 8 is greater than 40mm, development at the center portion of the resist substrate 8 becomes uneven. In this first embodiment, the distance between the developer application position P1 and the center of the resist substrate 8 is about 30 mm.

The laser light source 11 emits laser light L at a predetermined wavelength toward a monitor position P2 on the upper surface of the inorganic resist layer of the resist substrate 8 placed on the turntable 10. The laser light source 11 is provided so that the upper surface of the inorganic resist layer of the resist substrate 8 can be irradiated with the laser light L at an incident angle θ with respect to the normal line of the upper surface of the resist substrate 8 and in the radial direction of the resist substrate.

The monitor position P2 is different from the above-described developer application position P1, and is a distance b from the center of the resist substrate 8. It is preferable that the monitor position P2 be in the middle of the signal area where the projection and depression pattern is formed on the resist substrate 8. In this first embodiment, the distance b between the monitor position P2 and the center of the resist substrate 8 is about 40 mm.

The position of the monitor position P2 is set so that the resist substrate 8 is rotated in the direction from the monitor position P2 toward the developer application position P1. That is, in this first embodiment, the turntable 10 rotates in a direction from the monitor position P2 on the resist substrate 8 toward the developer application position P1.

It is preferable that the developer application position P1 be deviated from the monitor position P2 by an angle in the range of 60 ° to 120 ° with respect to the center of the resist substrate 8. If the angle is less than 60 °, the liquid surface of the developer at the monitoring position may be disturbed by the developer being coated. If the angle is larger than 120 °, the flow rate of the developer becomes unstable, so that the monitoring at the monitoring position P2 cannot be accurately performed.

In this first embodiment, the developer application position P1 is deviated from the monitor position P2 by an angle of about 90 ° in the rotational direction of the turntable 10 with respect to the center of the resist substrate 8.

First sensor R₀Measuring zero-order light L₀(reflected light), zero-order light is generated when the laser light L is reflected at the monitor position P2, where the laser light L irradiates the monitor position P2 on the upper surface of the inorganic resist layer of the resist substrate 8.

Second sensor R₁Measuring primary light L₁(amount of diffracted light), first order light, is generated when the laser light L, which irradiates the monitor position P2 on the upper surface of the inorganic resist layer of the resist substrate 8, is reflected at the monitor position P2.

First sensor R₀And a second sensor R₁The set position depends on the incident angle θ at which the monitor position P2 is irradiated with the laser light L emitted by the laser light source 11.

Table 1 shows the wavelength λ of the laser light L emitted from the laser light source 11, the incident angle θ of the laser light L incident on the surface of the inorganic resist layer 3, and the zeroth order light L of the laser light L reflected from the upper surface of the inorganic resist layer₀Angle of reflection theta₀And primary light L₁Diffraction angle of theta₁Simulation results of the relationship between them.

TABLE 1

The simulation results shown in table 1 are examples of using the resist substrate 8 of the master optical disc used for manufacturing the BD. The resist substrate 8 includes an inorganic resist layer 3, and a projection and depression pattern having a pit length of 0.32 μm is formed on the inorganic resist layer 3.

As shown in Table 1, when infrared rays having a wavelength of 680nm are used as the laser light L, the first order light L cannot be detected even if the incident angle θ is changed₁This is because the projection and depression pattern of the BD is formed on the resist substrate 8 with a small pit length.

When the upper surface of the inorganic resist layer is irradiated with blue laser light having a wavelength of 405nm and the incident angle θ is in the range of 20 ° to 60 °, the primary light L can be detected₁. That is, for the resist substrate 8 on which a fine concave-convex pattern having a track pitch of 0.32 μm for a BD is formed, the primary light L can be detected by using the laser light L having a wavelength of 405nm₁. Although a laser light L having a wavelength of 405nm was used in the simulation shown in Table 1, the primary light L could be detected as long as the wavelength was in the range of 400 to 410nm₁。

As shown in Table 1, the primary light L₁Diffraction angle of theta₁Depending on the angle of incidence theta of the laser light L. Zero order light L₀Angle of reflection theta₀Is substantially the same as the incident angle theta of the laser light L because of the zeroth order light L₀Is the reflected light of the laser light L.

In this first embodiment, according to the simulation results shown in table 1, the laser light source 11 that emits the laser light L having the wavelength in the range of 400 to 410nm is employed. First sensor R₀And a second sensor R₁Respectively arranged at zero-order light L at which the laser light L corresponding to the incident angle theta can be detected₀And primary light L₁The position of (a).

The simulation results shown in table 1 are simulation results in the case where the resist substrate 8 is dried. However, in practice, the resist substrate 8 is irradiated with the laser light L while the developer 13 is applied to the resist substrate 8. Therefore, the primary light L is due to the phase difference caused by the developer 13₁Diffraction angle of theta₁The actual data of (a) must be adjusted.

Due to the limitation of the developing device 15, the incident angle θ and the reflection angle θ of the laser light are preferable₀Equal to or less than 60 °, or more preferably equal to or less than 50 °. Preferably, the laser source and the sensor are arranged so as to detect the zeroth order light L when detecting the zeroth order light L₀First sensor R of the amount of light₀And detecting the primary light L₁Second sensor R of the amount of light₁At the closest position, zero-order light L₀Angle of reflection theta₀And the first order light L₁Diffraction angle of theta₁The difference therebetween is equal to or greater than 20 °.

In this first embodiment, the laser light source 11 is disposed above the resist substrate 8 such that the resist substrate 8 is irradiated with the laser light L emitted from the laser light source 11, and the incident angle θ of the laser light L at the monitor position P2 is 46 ± 2 °. In this case, since the laser light L is reflected by the surface of the inorganic resist layer 3 of the resist substrate 8 at a reflection angle θ of 46 ± 2 °₀Reflects so that zero order light L is detected₀First sensor R of the amount of light₀Is set along the reflection angle theta at the monitoring position P2₀Is a line of 46 + -2 deg..

Detecting the first order light L₁Second sensor R of the amount of light₁Is set along the diffraction angle theta at the monitoring position P2₁Line of 33 + -2 deg., wherein the primary light L₁Is diffracted by the surface of the inorganic resist layer 3 of the resist substrate 8. Diffraction angle theta of the first order light₁Corresponding to the incident angle theta₀Laser light L of 46 ± 2 °, and adjusted due to a phase difference caused by the developer 13.

In the developing apparatus 15, the resist substrate 8 is set on a rotatable turntable 10, and the turntable 10 is rotated. On the resist substrate 8, a resist pattern corresponding to the pattern is formed by exposureA latent image of a desired convex-concave pattern. At the same time, the developer 13 is released toward the developer application position P1 on the surface of the inorganic resist layer 3 of the resist substrate 8. While the developer 13 is being discharged, a monitor position P2 different from the developer application position P1 of the resist substrate 8 is irradiated with the laser light L. Zero order light L reflected at the monitoring position P2₀And primary light L₁Amount of light I₀And I₁Respectively by the first sensor R₀And a second sensor R₁And (6) detecting. Quantity of light I₀And I₁Respectively represent zero-order light L₀And primary light L₁The strength of (2).

FIG. 6 shows primary light L detected in the developing device 15 of the first embodiment₁For zero-order light L₀Light quantity ratio of (I)₁/I₀A change in (c). In fig. 6, the horizontal axis represents the development time, and the vertical axis represents the light amount ratio I₁/I₀。

In this first embodiment, the inorganic resist layer 3 is made of a positive resist so that the exposed portion 3a, which is a portion where a latent image is formed by exposure, is dissolved by development. Therefore, as development proceeds, the latent image is etched, and the exposed portion 3a is recessed to have a desired projection and depression pattern, so that the first order light as diffracted light is enhanced. Thus, the primary light L₁For zero-order light L₀Light quantity ratio of (I)₁/I₀And (4) increasing. In this first embodiment, the light quantity ratio I is monitored while continuing development₁/I₀. Light quantity ratio I₁/I₀When the target value is reached, the development is completed.

In this first embodiment, the developer application position P1 of the resist substrate 8 is away from the center of the resist substrate 8, and the monitor position P2 of the resist substrate 8 is different from the developer application position P1. Therefore, the flow velocity of the developer 13 at the monitor position P2 is stable, so that disturbance of the liquid surface can be suppressed. Therefore, the primary light L caused by the disturbance of the liquid surface can be reduced₁For zero-order light L₀Light quantity ratio of (I)₁/I₀Is fluctuating.

Comparative example

Fig. 7A is a schematic side view of the developing device 16 of the comparative example, and fig. 7B is a schematic plan view of the developing device. In fig. 7A and 7B, elements corresponding to those of fig. 5A and 5B are denoted by the same reference numerals, and repeated description will be omitted.

FIG. 8 shows primary light L detected in the developing device 16 of the comparative example₁For zero-order light L₀Light quantity ratio of (I)₁/I₀A change in (c). In fig. 8, the horizontal axis represents the development time, and the vertical axis represents the primary light L₁For zero-order light L₀Light quantity ratio of (I)₁/I₀。

As shown in fig. 7A and 7B, in the developing device 16 of the comparative example, the nozzle 12 for supplying the developer 13 is disposed directly above the center of the resist substrate 8, so that the developer application position P1 is at the center of the resist substrate 8. The comparative example is the same as the first embodiment except for the positions of the nozzle 12 and the developer application position P1.

As shown in fig. 8, in the developing device 16 of the comparative example, the primary light L₁For zero-order light L₀Light quantity ratio of (I)₁/I₀The variation with respect to the development time is unstable, which means that the monitoring accuracy is low. This is because, when the developer 13 is applied to the center of the resist substrate 8, the liquid surface of the developer 13 is disturbed at the monitor position P2, whereby the light amount ratio I₁/I₀Is affected by the turbulence of the liquid surface.

In contrast, in the developing apparatus 15 of the first embodiment, the developer application position P1 is away from the center of the resist substrate 8, thereby reducing disturbance of the liquid surface at the monitor position P2. Therefore, in the first embodiment, the primary light L is detected₁For zero-order light L₀Light quantity ratio of (I)₁/I₀Is stable with respect to the development time, as shown in fig. 6, so that the monitoring can be performed accurately. Therefore, in the first embodiment, when the light amount ratio I is set₁/I₀Can accurately monitor the degree of progress of development, so that the size of the pit openings in the exposed portion 3a etched by development can be substantially accurately uniformized. Thus, the master optical disc 9 having the accurately formed projection and depression pattern can be obtained.

In the conventional developing method, for example, the developing time is fixed. Therefore, a difference in the degree of development progress caused by the environmental change cannot be detected. However, in this first embodiment, the light quantity ratio I is monitored₁/I₀Can control the difference in the degree of development progress, whereby the development can be accurately controlled.

In this first embodiment, the developer application position P1 is away from the center of the resist substrate 8, whereby the light amount ratio can be detected and the developer 13 is applied while being not affected by the disturbance of the liquid surface. Therefore, the degree of progress of development can be detected without performing the drying step as in Japanese unexamined patent application publication No. 2006-344310. In this first embodiment, the monitoring position P2 is set in the signal area, so that the signal area is directly monitored. Therefore, it is not necessary to provide a special detection signal portion outside the signal area. This improves the yield. Further, the step of performing nitrogen purging, which affects the degree of development progress, is not required. The laser light source 11 and the sensor are prevented from being contaminated by smoke caused by nitrogen blowing.

The developing apparatus 15 and the developing method of the first embodiment are applied in the developing step of manufacturing a high-density master optical disc typified by a BD. However, embodiments of the present invention are not limited thereto.

Hereinafter, a developing apparatus and a developing method that can be applied to a developing step of manufacturing a master optical disc of BD, DVD, CD, or the like will be described.

Second embodiment

Fig. 9A is a schematic side view of a developing apparatus of a second embodiment of the present invention, and fig. 9B is a schematic plan view of the developing apparatus.

The developing device 17 of the second embodiment is used in a developing step of manufacturing a master optical disk of BD, DVD, and CD. The track pitch of the BD is 0.32 μm, the track pitch of the DVD is 0.74 μm, and the track pitch of the CD is 1.60 μm. In fig. 9A and 9B, elements corresponding to those of fig. 5A and 5B are denoted by the same reference numerals, and repeated description thereof is omitted.

As shown in fig. 9B, in the second embodiment, the developer application position P1 is shifted from the monitor position P2 by about 90 ° in the rotational direction of the turntable 10 with respect to the center of the resist substrate 8. In the second embodiment, a plurality of second sensors R are provided₁、R₁₂And R₁₃For detecting the primary light L reflected by the resist substrate 8₁. Since the track pitches of the projection and depression patterns of the BD, DVD, and CD are different from each other, the diffraction angles of the first order light of the laser light L reflected by the resist substrate 8 are different from each other. Therefore, in the second embodiment, the second sensors R corresponding to various formats are provided₁、R₁₂And R₁₃。

Using a second sensor R in developing the resist substrate 8 of BD₁. When the laser light L is reflected at the monitor position P2 of the resist substrate 8 of the BD, the second sensor R₁The first order light (diffracted light) L generated at this time is measured₁The amount of light of (c).

Using a second sensor R in developing the resist substrate 8 of the DVD₁₂. When the laser light L is reflected at the monitor position P2 of the resist substrate 8 of the DVD, the second sensor R₁₂The first order light (diffracted light) L generated at this time is measured₁₂The amount of light of (c).

Using a second sensor R in developing the resist substrate 8 of the CD₁₃. When the laser light L is reflected at the monitor position P2 of the resist substrate 8 of the CD, the second sensor R₁₃The first order light (diffracted light) L generated at this time is measured₁₃The amount of light of (c).

Table 2 shows the wavelength λ of the laser light L emitted from the laser light source 11, the incident angle θ of the laser light L, and the zeroth order light L of the laser light L reflected from the upper surface of the inorganic resist layer₀Angle of reflection theta₀And primary light L₁、L₁₂And L₁₃Diffraction angle of theta₁、θ₁₂And theta₁₃Simulation results of the relationship between them.

The simulation results shown in table 2 are examples of using the resist substrate 8 for the master optical disk used for manufacturing BD, DVD, and CD. Each of the resist substrates 8 includes an inorganic resist layer on which a projection and depression pattern having a predetermined pit length is formed.

TABLE 2

As shown in Table 2, when a laser beam having a wavelength of 680nm is used, the first order light L, which is diffracted light of the laser beam, is used₁₂And L₁₃Resist substrates for DVDs and CDs were detectable. However, the first order light L diffracted by the resist substrate 8 of the BD₁Are not detectable. As shown in Table 2, when the wavelength λ of the laser light L is 405nm and the incident angle θ of the laser light L is in the range of 20 ° to 60 °, the first order light L diffracted by the resist substrate 8 of BD, DVD, and CD₁、L₁₂、L₁₃Is detectable.

Therefore, in the second embodiment, laser light L having a wavelength in the range of 400 to 410nm of the resist substrate 8 usable for BDs, DVDs, and CDs is used as the laser light L for monitoring. As in the case of table 1, the simulation results shown in table 2 are simulation results in the case where the resist substrate 8 is dried. In fact, this data must be adjusted due to the phase difference caused by the developer 13. Adjusting the primary light L due to phase difference₁、L₁₂And L₁₃Diffraction angle of theta₁、θ₁₂And theta₁₃The actual data of (2).

Providing a second sensor R₁、R₁₂And R₁₃So as to have a diffraction when the laser light L from the laser light source 11 is incident on the resist substrate 8 at the incident angle θAngle of incidence theta₁、θ₁₂And theta₁₃Diffracted light L of₁、L₁₂And L₁₃Respectively enter the second sensor R₁、R₁₂And R₁₃. As in the first embodiment, a first sensor R is provided₀Such that when the laser light L has an incident angle theta, it has a reflection angle theta₀Zero-order light (reflected light) L of (═ θ)₀Into the first sensor R₀。

Diffraction angle θ in Table 2₁、θ₁₂And theta₁₃In the negative case, the second sensor R₁、R₁₂And R₁₃Is provided on the opposite side to the side of the laser light source 11 with respect to the broken line of fig. 9A.

In the second embodiment, the laser light source 11 is disposed at a position above the resist substrate 8 such that the monitor position P2 of the resist substrate 8 is irradiated with the laser light L emitted from the laser light source 11 at the incident angle θ of 46 ± 2 °. In this case, the laser light L is reflected by the surface of the inorganic resist layer 3 of the resist substrate 8 at a reflection angle θ of 46 ± 2 °₀And (4) reflecting. Thus, zero-order light L is detected₀First sensor R of the amount of light₀Arranged along the reflection angle theta from the monitored position P2₀Is a line of 46 + -2 deg..

Second sensor R for BD₁Arranged along the diffraction angle theta from the monitored position P2₁Line of 33 + -2 deg., wherein the second sensor R₁First order light L of laser light L for detecting surface diffraction of inorganic resist layer 3 of resist substrate 8₁The amount of light of (c). Second sensor R for DVD₁₂Arranged along the diffraction angle theta from the monitored position P2₁₂Line of 6 + -2 deg., wherein the second sensor R₁₂First order light L of laser light L for detecting surface diffraction of inorganic resist layer 3 of resist substrate 8₁₂The amount of light of (c). Second sensor R for CD₁₃Arranged along the diffraction angle theta from the monitored position P2₁₃Line of 27 + -2 deg., wherein the second sensor R₁₃First order light L of laser light L for detecting surface diffraction of inorganic resist layer 3 of resist substrate 8₁₃The amount of light of (c).

First order light L₁、L₁₂And L₁₃Diffraction angle of theta₁、θ₁₂And theta₁₃Angle of incidence theta corresponding to laser light L₀46 ± 2 °, and adjusted due to the optical path difference caused by the developer.

In the developing device 17, the resist substrate 8 of a BD, DVD, or CD on which a latent image is formed by exposure is set on a rotatable turntable 10, and the turntable 10 is rotated. In addition, the developer 13 is released toward the developer application position P1 on the upper surface of the inorganic resist layer. While the developer 13 is released, a monitor position P2 on the upper surface of the inorganic resist layer, which is different from the developer application position P1 of the resist substrate 8, is irradiated with the laser light L. Zero-order light L of laser light L reflected by the upper surface of the inorganic resist layer₀By the first sensor R₀Detected and each primary light L₁、L₁₂And L₁₃By the second sensor R₁、R₁₂And R₁₃A corresponding one of the detection.

As in the first embodiment, in the developing apparatus 17 of the second embodiment, the developer application position P1 is away from the center of the resist substrate 8, thereby reducing disturbance of the liquid surface at the monitor position P2. Therefore, in the second embodiment, each primary light L can be stably detected₁、L₁₂And L₁₃For zero-order light L₀Light quantity ratio of (I)₁/I₀Thereby, accurate monitoring can be performed. Therefore, in the second embodiment, when the light amount ratio I is set₁/I₀Can accurately monitor the degree of progress of development, whereby the size of pit openings of exposed portions etched by development can be substantially accurately uniformized. Thus, the master optical disc 9 having the accurately formed projection and depression pattern can be obtained.

Therefore, with the second embodiment, advantages similar to those of the first embodiment can be obtained.

In the developing device 17 of the second embodiment, a short-wavelength laser light L having a wavelength range of 400 to 410nm is used as the laser light L for monitoring, so that the developing device 17 can be used for the developing step for manufacturing BD, DVD, and CD.

Although three second sensors are employed in the second embodiment, the number of second sensors is not limited thereto. That is, the developing apparatus may be configured such that the developing apparatus can be used to develop the resist substrate 8 of the BD and the DVD. Alternatively, the developing apparatus may be configured such that the developing apparatus can be used to develop the resist substrate 8 of DVDs and CDs. In the second embodiment, a laser light L having a wavelength range of 400 to 410nm is used for monitoring. However, in order to monitor the developing step of the resist substrate 8 for DVDs and CDs, a laser having a wavelength of 680nm may be used.

In the first and second embodiments, the developer application position P1 is deviated from the monitor position P2 in the rotational direction of the turntable 10 by an angular range of 60 ° to 120 ° with respect to the center of the resist substrate 8. In the first and second embodiments, the direction of rotation of the turntable 10 is clockwise. However, even if the rotation direction is counterclockwise, the developer application position P1 may be deviated from the monitor position P2 in the rotation direction of the turntable 10 by an angular range of 60 ° to 120 ° with respect to the center of the resist substrate 8. By appropriately adjusting the position of the sensor, advantages similar to those of the first and second embodiments can be obtained.

Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions are possible, depending on design considerations and other factors, within the scope of the appended claims or their equivalents.

This application contains the relevant subject matter disclosed in japanese priority patent application JP 2008-.

Claims (5)

1. A developing method comprising the steps of:

providing a resist substrate on a rotatable turntable, the resist substrate including a substrate, an inorganic resist layer formed on the substrate, and a latent image formed by exposing the inorganic resist layer;

releasing a developer to a developer application position on an upper surface of the inorganic resist layer while rotating the turntable, the developer application position being away from a center of the resist substrate;

irradiating a monitoring position on an upper surface of the inorganic resist layer with laser light, the monitoring position being different from the developer coating position; and

continuously discharging the developer while detecting the amounts of zeroth order light and first order light of the laser light reflected by the upper surface of the inorganic resist layer and monitoring the light amount ratio of the first order light to the zeroth order light until the light amount ratio becomes a predetermined value,

wherein a distance between the developer application position and the center of the resist substrate is in a range of 20 to 40mm,

wherein the developer application position is deviated from the monitor position by an angle in a range of 60 ° to 120 ° in a rotational direction of the resist substrate with respect to a center of the resist substrate.

2. The developing method according to claim 1, wherein the developing solution,

wherein the laser has a wavelength in the range of 400 to 410 nm.

3. A developing apparatus comprising:

a turntable for rotating a resist substrate disposed on the turntable, the resist substrate including a substrate, an inorganic resist layer formed on the substrate, and a latent image formed by exposing the inorganic resist layer to light;

a nozzle for discharging a developer to a developer application position of a resist substrate provided on the turntable, the developer application position being away from a center of the resist substrate;

a laser light source for irradiating a monitoring position on an upper surface of an inorganic resist layer of the resist substrate with laser light, the monitoring position being different from the developer application position;

a first sensor for detecting an amount of zeroth order light of the laser light reflected by an upper surface of the inorganic resist layer; and

a second sensor for detecting a light amount of the primary light of the laser light reflected by an upper surface of the inorganic resist layer,

wherein a distance between the developer application position and the center of the resist substrate is in a range of 20 to 40mm,

wherein the developer application position is deviated from the monitor position by an angle in a range of 60 ° to 120 ° in a rotational direction of the resist substrate with respect to a center of the resist substrate.

4. The developing device according to claim 3,

wherein the laser has a wavelength in the range of 400 to 410 nm.

5. The developing device according to claim 3,

wherein a plurality of the second sensors are provided at positions different from each other.