JP2007234153A - Optical imprint mold and optical imprint method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately align a recording pattern center with a rotary axis on front and back sides of a disk without forming any alignment mark in a medium to be transferred in manufacturing of a disk substrate. <P>SOLUTION: Regarding an optical imprint mold for transferring a recording pattern to a disk substrate, the optical imprint mold having an alignment mark disposed in a position equivalent to an opening around the nontransferred rotary axis of a disk substrate center is provided. The optical imprint method includes the step of mounting a disk substrate in a substrate holder having alignment marks to be positioned in the stopper of the disk substrate and in the opening of the disk substrate center before the resist applied disk and the mold are pressed into contact with each other, and the step of aligning the disk substrate and the mold with each other based on the alignment marks of the optical imprint mold and the substrate holder. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mold for transferring a recording pattern onto a disk substrate (recording medium) in an optical imprint method, and an optical imprint method.

  In recent years, information recording apparatuses used in general-purpose computers and the like have been handling large volumes of data such as voice and moving images, and the recording capacity has been increasing. In magnetic recording media such as hard disks, which are information recording devices, “patterned media” that physically patterns the magnetic layer on the surface of the media to increase the recording capacity and physically isolates tracks and recording bits is promising. The period of adjacent recording bits is required to be about 30 nm or less.

  When the magnetic recording medium is set to this size, the conventional photolithography method cannot be used due to the limit of the wavelength of light. In addition, in the electron beam lithography method, the focused ion beam lithography method, and the like, fine processing of this size is possible, but the poor throughput is a problem.

Therefore, by using a mold made with a nano-order processing master manufactured by an electron beam lithography method, etc., the uneven pattern on the mold surface is transferred to the resist film by physically pressing the resist film applied on the magnetic layer. Then, an imprint method has been proposed in which the magnetic layer is patterned by etching using the uneven pattern of the resist film as a mask (see, for example, Patent Document 1).
The uneven pattern formation of the resist film is performed by thermal cycling or ultraviolet irradiation. A method using a thermal cycle is called a thermal imprint method, and a method using ultraviolet irradiation is called a photoimprint method.

  At present, the mainstream of magnetic recording media such as hard disks, which are information recording apparatuses, is to read and write on both sides by forming a magnetic film on both sides in order to increase the recording capacity per sheet (for example, Patent Document 2). reference.). In a hard disk drive equipped with a large number of disks, magnetic heads are individually arranged on the front and back surfaces, and only HSA (head stack assembly) is mounted with the head corresponding to the cylinder with the specified data area. Is set to a predetermined position by servo control, and the other HSAs are not controlled.

  At this time, if the cylinder for reading and writing changes from the front surface to the back surface, for example, if the front and back servo patterns are misaligned, it takes time to stabilize the position by the HSA servo on the back surface. There is a problem that the settling time corresponding to the data read time after cylinder switching is increased, and it is required that there is no deviation of the recording patterns on the front and back of the magnetic recording medium. In the case of a disk substrate, since it is required that there is no deviation between the center of the recording pattern and the rotation axis, the alignment is very important.

  In addition, in the thermal imprint used in Patent Document 1, the positioning pattern is transferred to the medium to be transferred in order to make the rotation axes coincide with each other on the front and back patterns, but this also causes a problem that the recording area of the medium is narrowed. there were.

JP 2003-157520 A JP 2002-319128 A

  The present invention has been made in order to solve the above-described problems. In manufacturing a disk substrate (recording medium) in the imprint method, the center of the recording pattern and the rotation axis can be set without providing an alignment mark on the transfer medium. To provide an optical imprint mold and an optical imprint method capable of accurately aligning the front and back of a disk.

  In order to achieve the above object, a first invention of the present invention is an optical imprint mold for transferring a recording pattern to a disk substrate, and a position corresponding to an opening around a rotation axis that is not transferred at the center of the disk substrate. An optical imprint mold characterized in that an alignment mark is provided on the optical imprint mold.

  The second invention is an optical imprinting method for forming a recording pattern on a disk substrate, wherein a disk substrate stopper and a center of the disk substrate are bonded before the resist-coated disk substrate and the mold are pressure-bonded. A disk substrate is placed on a substrate holder having an alignment mark so as to be positioned in the opening of the optical disk. Next, based on the alignment mark of the optical imprint mold and the alignment mark of the substrate holder, It is an optical imprint method characterized by aligning molds.

  According to the present invention, by manufacturing a quartz mold having an alignment mark, in the manufacture of a disk substrate (recording medium) in the imprint method, a shape and recording having a patterned medium without forming an alignment mark on the disk substrate. It is possible to easily and accurately provide a transfer pattern in which there is no deviation between the pattern and the rotation axis of the disk substrate.

An embodiment according to the present invention will be described below.
FIG. 1 is a view for explaining an optical imprint mold for manufacturing a disk substrate according to the present invention. The mold used is a quartz mold. Fig.1 (a) shows the quartz mold front (surface), (b) shows a cross section.

  Reference numeral 120 denotes a quartz substrate, and reference numeral 121 denotes a recording pattern provided on the quartz substrate 120. The alignment mark 122 located in the opening at the center of the disk substrate is an opaque pattern and is a pattern that is not transferred to the recording medium.

<Mold production>
Next, a method for manufacturing a mold will be described with reference to FIG. A synthetic quartz substrate for a photomask of 6025 size having a thickness of Cr of 100 nm and a resist thickness of 400 nm was used as a base substrate for the mold (FIG. 2B). A dot pattern of about 100 to 200 nm was drawn with an electron beam drawing apparatus, and then a resist pattern was formed by organic development (FIG. 2C). The conditions at this time were a drawing dose of 100 μC / cm 2 and a development time of 2 minutes.

  Next, a Cr pattern was formed by Cr etching using an ICP dry etching apparatus and O 2 plasma ashing using a barrel ashing apparatus (FIG. 2D). The conditions for Cr etching were Cl2 flow rate 20 sccm, O2 flow rate 10 sccm, He flow rate 30 sccm, pressure 3 Pa, ICP power 500 W, RIE power 50 W, etching time 40 seconds, and O2 plasma ashing conditions were O2 flow rate 500 sccm, pressure 30 Pa, RF The power was 1000W.

  Next, using an ICP dry etching apparatus, the quartz substrate was etched using the patterned Cr layer as an etching mask (FIG. 2E). At this time, the quartz etching conditions were C4F8 flow rate 10 sccm, O2 flow rate 10-25 sccm, Ar flow rate 75 sccm, pressure 1-2 Pa, ICP power 200 W, RIE power 550 W, and etching time 90 seconds.

  Next, a quartz mold was manufactured by wet peeling cleaning of the Cr layer (FIG. 2 (f)). At this time, by covering the alignment mark part with Kapton tape or the like and leaving Cr, the alignment mark on the mold does not affect the formation of the transfer pattern. A mold provided with the above alignment mark 133 (opaque) was manufactured.

<Manufacture of disk substrates>
Next, using the quartz mold of the present invention, optical imprinting was performed with an optical imprinting apparatus to manufacture a disk substrate.
First, the pattern surface of the quartz mold 150 shown in FIG. 3A was previously coated with a fluorine-based surface treating agent EGC-1720 (manufactured by Sumitomo 3M) as a release agent. Subsequently, as shown in FIG. 3B, a photocurable resist PAK-01 (manufactured by Toyo Gosei Co., Ltd.) 152 is applied to the substrate to be imprinted on a donut-shaped silicon substrate 151 by a spray method to a thickness of 300 nm. Coated with.

  Subsequently, after aligning the quartz mold 150 and the silicon substrate 151, as shown in FIG. 3C, the quartz mold 150 is pressure-bonded to the photocurable resist 152, and light is irradiated from the back surface of the mold 150. The photo-curable resist 152 was cured. The conditions for optical imprinting were as follows: no pre-baking (room temperature), pressing pressure 2 MPa, UV wavelength 365 nm, UV exposure 40 mJ / cm 2.

  Next, as shown in FIG. 3D, the quartz mold is released, and the thin residual film of the photo-curable resist 152 to which the pattern of the mold 150 is transferred is removed by the O2RIE method or the like. ), A silicon substrate on which a resist pattern for physically isolating the alignment mark and the recording bit provided so as to be located at the opening in the center of the disk substrate was obtained.

  Here, the alignment of the quartz mold 150 and the silicon substrate 151 performed before the step of FIG. 3C will be described with reference to FIG. 4A and 4B are a projection view (a) and a cross-sectional view (b) showing how the alignment marks provided on the mold and the substrate holder of the disk substrate are aligned. On one disk substrate side, a donut disk substrate 144 is installed on a substrate holder 146 having a stopper such as 145. The substrate holder 146 is provided with an alignment mark 143 so as to be positioned at the opening in the center of the disk substrate.

  On the other mold side, the quartz mold 140 is vacuum-sucked to the mold holder 141. The mold holder 141 has a moving mechanism for the rotation angle θ on the X direction, the Y direction, and the XY plane. The alignment marks on the mold 140 and the substrate holder 146 were observed with a microscope 142 and aligned.

  According to this method, since the resist is cured by a photoreaction, there is no thermal cycle (it may be at room temperature), the processing time can be greatly shortened, and the positional accuracy is not degraded by the thermal cycle. Further, since the photocurable resist is a liquid having a low viscosity, the pattern can be transferred without pressing the mold to the photocurable resist with a high pressure as in the case of thermal imprinting. Therefore, a decrease in positional accuracy and mold damage due to the press pressure are dramatically reduced.

  The present invention can be used in a process of transferring a recording pattern to a disk substrate. In particular, it can be used for a recording medium having recording layers on both sides of a disk.

It is a figure explaining the optical imprint mold which concerns on this invention. It is sectional drawing which shows the manufacturing process of a quartz mold. It is sectional drawing which shows the pattern formation process by the optical imprint method. It is a figure explaining the alignment method in the optical imprint method of this invention.

Explanation of symbols

120 ... quartz substrate 121 ... recording pattern 122 ... alignment mark 130 ... quartz substrate 131 ... chromium 132 ... resist 133 ... alignment mark 140 ... quartz mold 141 ... Mold holder 142 ... Microscope 143 ... Alignment mark 144 ... Recording medium 145 ... Stopper 146 ... Substrate holder 150 ... Quartz mold 151 ... Silicon substrate 152 ... Resist

Claims (2)

  An optical imprint mold for forming a recording pattern on a disk substrate, wherein an alignment mark is provided at a position corresponding to an opening where no pattern is formed around a rotation axis in the center of the disk substrate. Print mold. It is an optical imprint method for forming a recording pattern on a disk substrate, and before press-bonding a resist-coated disk substrate and a mold,
Place the disk substrate on the substrate holder having the alignment mark so as to be positioned at the disk substrate stopper and the opening in the center of the disk substrate,
Next, based on the alignment mark of the optical imprint mold according to claim 1 and the alignment mark of the substrate holder, the disk substrate and the mold are aligned.