JP2017079275A - Glass plate for imprint mold, laminated plate for imprint mold, and imprint mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass plate for an imprint mold capable of improving dimension accuracy of an opening pattern formed in a transfer material.SOLUTION: Disclosed is a glass plate for an imprint mold in which, on one main surface, a substantially rectangular protruding surface is provided whose periphery is surrounded by a step and which further protrudes than the periphery. In a substantially rectangular area excluding a portion within 1.5 mm from the outer peripheral edge of the protruding surface out of the protruding surface, out of area waviness which is measured from one end of the area to the other end of the area in a direction parallel to one side of the area, the size of the maximum height difference of a frequency component in a wavelength range of 50 μm or more and 50 mm or less is equal to or less than 10 nm.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a glass plate for imprint mold, a laminated plate for imprint mold, and an imprint mold.

  As an alternative technique to the photolithography method, an imprint method has attracted attention (see, for example, Patent Documents 1 to 3). The imprint method is a technique in which a transfer material is sandwiched between a mold and a substrate, and an uneven pattern of the mold is transferred to the transfer material. In the photolithography method, the resolution is limited by the wavelength of light used for exposure, but in the imprint method, a pattern can be formed according to the pattern carved in the mold, and a very fine pattern can be formed. In addition, an expensive optical system apparatus is unnecessary as compared with the photolithography method, and it can be expected to perform ultrahigh resolution lithography with a low-cost apparatus. The imprint method can be applied to the manufacture of various products such as antireflection sheets, biochips, magnetic recording media as well as semiconductor elements.

  The imprint method is expected to be developed especially for semiconductor integrated circuits. 2. Description of the Related Art In recent years, semiconductor integrated circuits have been miniaturized and integrated, and photolithography apparatuses have been improved in accuracy as a pattern transfer technique for realizing the fine processing. However, there has been a problem that the price of the apparatus becomes very high because the apparatus must be increased in size as the pattern becomes finer, and it is necessary to control the apparatus with high precision.

  On the other hand, there is an imprint method for performing a fine pattern at a low cost, and it is said that a pattern of about 10 nanometers can be transferred. The imprint method has been studied for its application to mass recording medium recording bit formation, semiconductor integrated circuit pattern formation, and the like, and is being studied for mass production.

  Here, high throughput is one of the problems in applying imprint technology to mass production. Even if the price of the imprint apparatus is low, if the throughput is low, the product cost becomes high, and a cost merit cannot be obtained as compared with a product manufactured by a conventional photolithography method.

  In the pattern transfer process, air bubbles are easily caught between the mold and the substrate. The entrained bubbles are gradually absorbed by the transfer material, and the bubbles disappear. In the transfer process, it is necessary to wait until the transfer material completely fills the space surrounded by the uneven pattern and the substrate. This is because when the transfer material is solidified with bubbles that cannot be absorbed, pattern defects are caused.

  Furthermore, as a technique for reducing the amount of entrained bubbles, a technique has been developed in which a mold having a non-through hole is transferred while being curved on the surface opposite to the pattern. In this state, the mold center and the transfer material are first contacted, and in this state, the contact area with the transfer material is gradually expanded from the mold center to the outer periphery of the mold. Can be made.

Special table 2009-536591 JP 2015-26712 A JP 2013-211450 A

  A glass plate is generally used for the production of the mold. At the center of one main surface of the glass plate, a projecting surface called a mesa is formed by digging up the outer periphery of the main surface and surrounding the periphery with a step. A mold is obtained by forming an uneven pattern on the projecting surface.

  When a transfer material is sandwiched between the mold and the substrate and the concavo-convex pattern of the mold is transferred to the transfer material, a residual film is formed between the convex portion of the concavo-convex pattern of the mold and the substrate. The remaining film is removed by etching or the like, and an opening pattern is formed in the transfer material.

  If the thickness of the remaining film (Residual Layer Thickness) is not uniform, the dimensional accuracy of the opening pattern formed on the transfer material will deteriorate. Therefore, it is required that the undulation of the protruding surface of the glass plate is small so that the thickness of the remaining film becomes uniform.

  Conventionally, during the glass plate manufacturing process, unintended chemical corrosion, contact damage, or the like has occurred on the protruding surface, and the waviness of the protruding surface sometimes increased. As a result, the dimensional accuracy of the opening pattern formed on the transfer material may deteriorate.

  This invention is made | formed in view of the said subject, Comprising: The main objective is to provide the glass plate for imprint molds which can improve the dimensional accuracy of the opening pattern formed in a transcription | transfer material.

In order to solve the above problems, according to one aspect of the present invention,
On one main surface, a glass plate for imprint mold having a substantially rectangular protruding surface that is surrounded by a step and protrudes from the periphery,
Measured from one end of the region to the other end of the region in a direction substantially parallel to one side of the region in a substantially rectangular region excluding a portion within 1.5 mm from the outer peripheral edge of the projecting surface. An imprint mold glass plate is provided in which the maximum height difference of frequency components in the wavelength range of 50 μm or more and 50 mm or less among the undulations in the region is 10 nm or less.

  According to one aspect of the present invention, there is provided an imprint mold glass plate capable of improving the dimensional accuracy of an opening pattern formed in a transfer material.

It is a top view of the mold produced using the glass plate by one Embodiment. It is sectional drawing of the mold along the II-II line of FIG. It is sectional drawing of the deformation | transformation state of the mold shown in FIG. It is sectional drawing of the deformation | transformation cancellation | release state of the mold shown in FIG. It is a top view of the glass plate by one Embodiment. It is sectional drawing of the glass plate along the VI-VI line of FIG. It is a figure which shows progress which forms an uneven | corrugated pattern in the protrusion surface of FIG. FIG. 8 is a diagram illustrating a process of forming a concavo-convex pattern on the protruding surface of FIG. 6 following FIG. 7. FIG. 9 is a diagram illustrating a process of forming a concavo-convex pattern on the protruding surface of FIG. 6 following FIG. 8. It is sectional drawing which expands and shows a part of protrusion surface of FIG. It is sectional drawing which shows the mold formed by forming an uneven | corrugated pattern in the protrusion surface of FIG. It is sectional drawing which shows the transfer material and the base material which transcribe | transferred the uneven | corrugated pattern of the mold of FIG. It is sectional drawing which expands and shows a part of FIG. It is sectional drawing which shows the state after the etching of the transfer material of FIG. It is a figure which shows an example of the wavelength (lambda) of the wave | undulation of a protrusion surface, and the uniformity CDU of the width | variety of the convex part after an etching. It is a flowchart of the manufacturing method of the glass plate by one Embodiment. It is sectional drawing of the glass plate after completion of the non-through-hole formation process of FIG. It is sectional drawing of the glass plate after completion of the protrusion surface formation process of FIG.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the drawings, the same or corresponding components are denoted by the same or corresponding reference numerals, and description thereof is omitted. In this specification, the imprint mold is also simply referred to as a mold. In addition, in this specification, “substantially rectangular” includes not only rectangles and squares but also shapes in which corners of the rectangles and squares are chamfered, and sides of the rectangles and squares are zigzag.

  FIG. 1 is a plan view of a mold manufactured using a glass plate according to an embodiment. In FIG. 1, the X direction is a direction parallel to one side of the substantially rectangular protruding surface, and the Y direction is a direction perpendicular to the X direction. The same applies to the other drawings. FIG. 2 is a cross-sectional view of the mold along the line II-II in FIG. FIG. 3 is a cross-sectional view of the mold shown in FIG. 2 in a deformed state. 4 is a cross-sectional view of the mold shown in FIG.

  As shown in FIG. 4, the mold 10 sandwiches the transfer material 17 between the substrate 15 and transfers the uneven pattern of the mold 10 to the transfer material 17. The concavo-convex pattern of the transfer material 17 is a inverting pattern of the mold 10. The uneven pattern of the mold 10 is a pattern called a line and space in FIG. The line-and-space line is, for example, perpendicular to the X direction and parallel to the Y direction. In FIG. 1, the line pitch is shown larger than the actual pitch for convenience. In addition, the uneven | corrugated pattern of a mold is not limited to the pattern shown in FIG.

The mold 10 is made of, for example, glass. The glass is preferably quartz glass containing 90% by mass or more of SiO ₂ . The upper limit of the SiO ₂ content in the quartz glass is 100% by mass.

  Quartz glass has higher ultraviolet transmittance than general soda lime glass. Quartz glass has a smaller coefficient of thermal expansion than ordinary soda lime glass, and its dimensional change due to temperature changes is small.

Quartz glass may contain TiO ₂ in addition to SiO ₂ . The greater the TiO ₂ content, the greater the density of OH groups on the glass surface, and the higher the affinity between the glass surface and the transfer material 17. Therefore, the disappearance time of bubbles entrained between the mold 10 and the substrate 15 can be shortened.

Quartz glass may contain 90 to 95% by mass of SiO ₂ and 5 to 10% by mass of TiO ₂ . When the TiO ₂ content is 5 to 10% by mass, the coefficient of thermal expansion near room temperature is substantially zero, and the dimensional change near room temperature hardly occurs.

Quartz glass may contain trace components other than SiO ₂ and TiO ₂ , but preferably does not contain trace components.

  As shown in FIG. 2, the mold 10 has a first main surface 11 and a second main surface 12. In a natural state where no external force is applied, the first main surface 11 and the second main surface 12 are substantially parallel.

  At the central portion of the first main surface 11, a projecting surface 13 called a mesa is formed that is surrounded by a step and projects beyond the periphery. In plan view, the shape of the protruding surface 13 is substantially rectangular as shown in FIG. 1, for example. An uneven pattern to be transferred to the transfer material 17 is formed on the protruding surface 13.

  On the other hand, a non-through hole 14 having a predetermined depth is formed at the center of the second main surface 12. The shape of the non-through hole 14 is, for example, a cylinder as shown in FIGS. The shape of the non-through hole 14 may be a truncated cone, a prism, a truncated pyramid, or the like.

  As shown in FIG. 1, the protruding surface 13 is disposed inside the opening edge 14 a of the non-through hole 14 in plan view. Further, in the plan view, the center of the protruding surface 13 and the center of the non-through hole 14 coincide with the center of the mold 10.

  As shown in FIG. 2, the portion of the mold 10 where the non-through hole 14 is formed is thinner than the peripheral portion thereof, and thus is easily bent and deformed by an external force. Therefore, as shown in FIG. 3, the projecting surface 13 can be bent and deformed convexly toward the substrate 15 around the center line of the non-through hole 14. This bending deformation is performed by, for example, pressing the outer peripheral surface of the mold 10 or the inner bottom surface of the non-through hole 14. The inner bottom surface of the non-through hole 14 may be pressed by the pressure of the gas chamber formed in the non-through hole 14.

  Next, with reference to FIGS. 3 to 4 again, an imprint method using the mold 10 having the above-described configuration will be described.

  As shown in FIG. 3, in a state where the protruding surface 13 of the mold 10 is bent and deformed convexly toward the substrate 15, the mold 10 and the substrate 15 are brought close to each other, and the liquid transfer material 17 previously applied to the substrate 15 is applied. The protruding surface 13 of the mold 10 is brought into contact with the mold 10.

  Thereafter, before the transfer material 17 is solidified, the projecting surface 13 is returned from the deformed state shown in FIG. 3 to the deformed release state shown in FIG. Thereby, the protruding surface 13 gradually comes into contact with the transfer material 17 from the central portion toward the outer peripheral portion. The gas between the mold 10 and the substrate 15 can easily escape and gas confinement can be suppressed.

  After the transfer material 17 is solidified, the transfer material 17 and the mold 10 are separated. A product constituted by the uneven layer formed by solidifying the transfer material 17 and the substrate 15 is obtained. The concavo-convex pattern of the product is a concavo-convex pattern of the mold 10 that is substantially inverted.

  FIG. 5 is a plan view of a glass plate according to an embodiment. FIG. 6 is a cross-sectional view of the glass plate taken along line VI-VI in FIG.

  The glass plate 20 has a first main surface 21 and a second main surface 22, a protruding surface 23 on the first main surface 21, and a non-through hole 24 with a predetermined depth on the second main surface 22. A mold 10 shown in FIGS. 1 and 2 is obtained by digging a part of the projecting surface 23 by etching or the like and forming an uneven pattern on the projecting surface 23.

  7 to 9 are views showing a process of forming the concave / convex pattern on the protruding surface of FIG.

  First, as shown in FIG. 7, an etching protective film 30 is formed on the glass plate 20. The etching protection film 30 may be a general one, and is formed of, for example, a metal or a metal compound. The etching protective film 30 may have either a single layer structure or a multilayer structure. The glass plate 20 and the etching protective film 30 constitute an imprint mold laminate.

  The etching protective film 30 is, for example, a single metal, alloy, nitride, oxide, carbide, carbonitride, oxynitride, or oxycarbonitride containing at least one metal element selected from Cr, Al, Zn, and Fe It may be formed of an object. Alternatively, the etching protection film 30 is formed of a tantalum compound such as Ta, TaHf, TaZr, or TaHfZr, or a composite material that includes a tantalum compound as a main material and a subsidiary material such as Be, Ge, Nb, Si, C, or N. May be.

  The etching protection film 30 is formed by a physical vapor deposition method (PVD method) such as sputtering or vacuum deposition, a chemical vapor deposition method (CVD method), an atomic layer deposition method (ALD method), or the like. The thickness of the etching protective film 30 is, for example, 2 to 10 nm. In order to form a fine pattern in the etching protective film 30, the thickness of the etching protective film 30 is desirably as small as possible, desirably 5 nm or less, and more desirably 3 nm or less.

  Next, as shown in FIG. 8, a resist film 40 having an opening pattern is formed on the etching protection film 30. The formation method may be any of an electron beam lithography method, a photolithography method, and an imprint method.

  Although the resist film 40 shown in FIG. 8 is formed on the entire surface of the etching protective film 30, it may be formed in the etching protective film 30 in a region overlapping with the protruding surface 23 at least in plan view.

  Next, by etching the etching protection film 30 partially protected by the resist film 40, an opening pattern is formed in the etching protection film 30 as shown in FIG. The opening pattern is substantially the same as the opening pattern of the resist film 40 shown in FIG. The resist film 40 that is no longer needed may be removed as shown in FIG.

  Next, the projecting surface 23 partially protected by the etching protection film 30 is etched to form an uneven pattern on the projecting surface 23 as shown in FIG. The unnecessary etching protection film 30 is removed as shown in FIG.

  FIG. 10 is an enlarged cross-sectional view showing a part of the protruding surface of FIG. In FIG. 10, the waviness of the protruding surface is exaggerated. FIG. 11 is a cross-sectional view showing a mold in which an uneven pattern is formed on the protruding surface of FIG. FIG. 12 is a cross-sectional view showing a transfer material to which the concave / convex pattern of the mold of FIG.

  The uneven pattern of the mold 10 is formed on the protruding surface 23 by digging down a part of the protruding surface 23 of the glass plate 20 by etching or the like. Therefore, the top surface of the convex portion of the concavo-convex pattern of the mold 10 coincides with the protruding surface 23 of the glass plate 20.

  When the projecting surface 23 has a slight undulation as shown in FIG. 10, the height of the top surface of the convex portion of the concavo-convex pattern of the mold 10 varies as shown in FIG. 11. As a result, as shown in FIG. 12, the thickness T of the residual film formed between the convex part of the concave / convex pattern of the mold 10 and the substrate 15 varies. The variation in the thickness T of the remaining film corresponds to the undulation of the protruding surface 23.

  FIG. 13 is an enlarged cross-sectional view showing a part of FIG. 14 is a cross-sectional view showing a state after etching of the transfer material of FIG. In FIG. 14, the alternate long and two short dashes line indicates a state before the transfer material is etched.

  The transfer material 17 shown in FIG. 13 has a concavo-convex pattern in which the concavo-convex pattern of the mold 10 is substantially inverted, and includes a first convex portion 171, a second convex portion 172, a residual film 173, and the like. The remaining film 173 is formed on the substrate 15. The first convex portion 171 and the second convex portion 172 protrude from the remaining film 173 to the side opposite to the substrate 15.

  The first convex portion 171 and the second convex portion 172 have an isosceles trapezoidal cross-sectional shape in which the length of the lower base is W1 and the inner angles of both ends of the lower base are θ. The thickness T of the remaining film 173 has a maximum value T1 in the vicinity of the first convex portion 171 and a minimum value T2 (T2 <T1) in the vicinity of the second convex portion 172.

  The transfer material 17A shown in FIG. 14 is obtained by etching the transfer material 17 shown in FIG. 13 in the thickness direction. As the etching, for example, dry etching is used, and specifically, etching using oxygen plasma or the like is used.

  The etched transfer material 17A has an opening pattern in which the substrate 15 is exposed in the concave portion of the concave / convex pattern, and includes a first convex portion 171A, a second convex portion 172A, and the like. The first convex portion 171A and the second convex portion 172A protrude from the substrate 15.

  The first projecting portion 171A after etching has the same cross-sectional shape as the first projecting portion 171 before etching, and is an isosceles trapezoidal shape having a lower base length of W1 and inner angles of both ends of the lower base being θ. It has a cross-sectional shape. On the other hand, the second convex portion 172A after etching has a smaller cross-sectional shape than the second convex portion 172 before etching, the length of the lower base is W2, the inner angles of both ends of the lower base are θ, etc. It has a trapezoidal cross-sectional shape. In this case, the following formula (1) is established.

上記式（１）を変形することで、下記式（２）が導出される。

The following formula (2) is derived by modifying the above formula (1).

上記式（２）は、エッチング後の第２凸部１７２Ａの幅Ｗ２を算出する式である。エッチング前の第２凸部１７２の近傍では、残膜１７３の厚さＴが最小値Ｔ２となる。上記式（２）から、残膜１７３の厚さＴ（図１２参照）のばらつきと、エッチング後の凸部の幅Ｗ（不図示）のばらつきとの関係が分かる。

The above equation (2) is an equation for calculating the width W2 of the second convex portion 172A after etching. In the vicinity of the second convex portion 172 before etching, the thickness T of the remaining film 173 becomes the minimum value T2. From the above equation (2), the relationship between the variation in the thickness T (see FIG. 12) of the remaining film 173 and the variation in the width W (not shown) of the protrusion after etching can be seen.

  The variation in the thickness T of the remaining film 173 corresponds to the undulation of the protruding surface 23 as described above. The waviness of the protruding surface 23 can be approximated by superposition of a plurality of sine waves, and can be decomposed into a plurality of sine waves.

  Therefore, for simplification, let us consider a case where the waviness of the protruding surface 23 can be approximated by a specific sine wave. In this case, the width W of the protrusion after etching at the position of the X direction coordinate x is expressed by the following formula (3) obtained by modifying the above formula (2).

上記式（３）において、Ａは正弦波の振幅、λは正弦波の波長である。上記式（３）を用いて、エッチング後の凸部の幅の標準偏差σを求めることができる。この標準偏差σの３倍の値（３σ）は、ＣＤＵ（Critical Dimension Uniformity）と呼ばれ、エッチング後の凸部の幅の均一性を表す値として用いられる。ＣＤＵが小さいほど、エッチング後の凸部の幅の均一性が良い。

In the above formula (3), A is the amplitude of the sine wave, and λ is the wavelength of the sine wave. Using the above equation (3), the standard deviation σ of the width of the protrusion after etching can be obtained. A value (3σ) that is three times the standard deviation σ is called CDU (Critical Dimension Uniformity), and is used as a value that represents the uniformity of the width of the protrusion after etching. The smaller the CDU, the better the uniformity of the width of the protrusion after etching.

  FIG. 15 is a diagram illustrating an example of the relationship between the wave length λ of the waviness of the protruding surface and the uniformity CDU of the width of the protrusion after etching. In FIG. 15, the horizontal axis represents the wave length λ, the vertical axis represents the CDU, and the black circle represents the CDU calculation point.

  In FIG. 15, the pitch in the X direction of the protrusions is 30 nm, the maximum value W1 of the width W of the protrusions is 15 nm, the inner angle θ at both ends of the bottom of the isosceles trapezoid that is the cross-sectional shape of the protrusions is 87 °, The amplitude A is assumed to be 5 nm. The CDU selects 668 convex portions every 2000 out of 1334001 convex portions arranged at an equal pitch in a section of about 40 mm along the X direction, and sets the width of each selected convex portion to the above. It calculated using Formula (3) and calculated | required from the calculation result. Even if the pitch in the X direction of the convex portion, the maximum value W1 of the width W of the convex portion, the internal angle θ at both ends of the lower base of the isosceles trapezoid, the amplitude A of the sine wave, etc., the relationship shown in FIG. There is almost no change in the trend.

  The present inventors have found from FIG. 15 and the like that the frequency component in the wavelength range of 50 μm or more and 50 mm or less among the undulations of the protruding surface 23 increases CDU, and deteriorates the uniformity of the width of the protrusion after etching. . Further, the present inventor has found that the uniformity of the width of the convex portion after etching can be improved by suppressing the magnitude of the maximum height difference of the frequency component in the wavelength range.

  The waviness of the protruding surface 23 can be measured by, for example, scanning white light interferometry. In scanning white light interferometry, it is difficult to accurately measure the waviness of a portion of the protruding surface 23 within 1.5 mm from the outer peripheral edge 23a of the protruding surface 23 (hereinafter also simply referred to as the outer peripheral portion of the protruding surface 23). It is. Therefore, the undulation of the protruding surface 23 is measured in a substantially rectangular area SA (area surrounded by a two-dot chain line in FIG. 5) of the protruding surface 23 excluding the outer peripheral portion of the protruding surface 23.

  According to the present embodiment, the maximum height difference of frequency components in the wavelength range of 50 μm or more and 50 mm or less among the undulations of the region SA measured from one end of the region SA to the other end of the region SA in the X direction (hereinafter referred to as “below”). , Also simply referred to as “the magnitude of the maximum height difference in the X direction”) is 10 nm or less. The measurement of the maximum height difference in the X direction is repeated by changing the position in the Y direction, and is performed over the entire area SA. At each Y-direction position, the magnitude of the maximum height difference in the X direction may be 10 nm or less. If the magnitude of the maximum height difference in the X direction is 10 nm or less, the uniformity of the width of the protrusion after etching is good. The magnitude of the maximum height difference in the X direction is preferably 7 nm or less, and more preferably 6 nm. From the viewpoint of manufacturing the glass plate 20, the magnitude of the maximum height difference in the X direction is preferably 1.5 nm or more.

  The line and space lines of this embodiment are perpendicular to the X direction and parallel to the Y direction, but the direction can be changed. It is preferable that the undulation in the Y direction is comparable to the undulation in the X direction so that the orientation can be changed.

  Specifically, the magnitude of the maximum height difference of the frequency components in the wavelength range of 50 μm or more and 50 mm or less among the undulations of the area SA measured from one end of the area SA to the other end of the area SA in the Y direction (hereinafter simply referred to as “the height difference”). (Also referred to as “the maximum height difference in the Y direction”) is 10 nm or less. The measurement of the maximum height difference in the Y direction is repeatedly performed by changing the position in the X direction, and is performed over the entire area SA. The maximum height difference in the Y direction may be 10 nm or less at each X direction position. The magnitude of the maximum height difference in the Y direction is preferably 7 nm or less. In addition, from the viewpoint of manufacturing the glass plate 20, the magnitude of the maximum height difference in the Y direction is preferably 1.5 nm or more.

  In addition, although mentioned later in detail, in this embodiment, an appropriate process is performed in the manufacturing process (refer FIG. 16) of the glass plate 20 so that the waviness of the protrusion surface 23 may not become large. Therefore, (1) after the main surface polishing step S11 and before the non-through hole forming step S12, (2) after the non-through hole forming step S12 and before the protruding surface forming step S13, (3) protruding In the three periods after the surface forming step S13, the waviness of the protruding surface 23 is substantially the same.

  FIG. 16 is a flowchart of a glass plate manufacturing method according to an embodiment. FIG. 17 is a cross-sectional view of the glass plate after the non-through hole forming step of FIG. 16 is completed. 18 is a cross-sectional view of the glass plate after completion of the protruding surface forming step of FIG. In FIG. 18, an alternate long and two short dashes line shows the state of the glass plate before the start of the protruding surface forming step.

  The manufacturing method of the glass plate for imprint molds has main surface grinding | polishing process S11, non-through-hole formation process S12, and protrusion surface formation process S13, as shown in FIG. The order of these steps is not limited to the order shown in FIG. For example, in FIG. 16, the protruding surface forming step S13 is performed after the non-through hole forming step S12. However, the order may be reversed, and the non-through hole forming step S12 may be performed after the protruding surface forming step S13. . Further, the protruding surface forming step S13 may be performed in the middle of the non-through hole forming step S12.

  In the main surface polishing step S11, the entire first main surface 21 of the glass plate 20 is polished. In the main surface polishing step S11, the first main surface 21 may be repeatedly polished while exchanging the polishing pad and / or the polishing slurry. In the main surface polishing step S11, the second main surface 22 may also be polished by the same method.

  A polishing pad may be arrange | positioned at the plate | board thickness direction both sides of the glass plate 20, and may grind | polish the 1st main surface 21 and the 2nd main surface 22 simultaneously. In addition, a polishing pad may be arrange | positioned at the plate | board thickness direction one side of the glass plate 20, and may grind | polish the 1st main surface 21 and the 2nd main surface 22 in order. The order is not particularly limited, and either may be polished first.

  The polishing pad is used by being attached to a surface plate. The polishing surface of the polishing pad is larger than the first main surface 21 and the second main surface 22. The radius of the polishing surface of the polishing pad may be larger than the diameter of the carrier that holds the glass plate 20. In this case, the carrier is rotated around the center line of the carrier while being revolved around the center line of the polishing pad.

  As the polishing pad, for example, a urethane polishing pad, a non-woven polishing pad, a suede polishing pad, or the like is used. Moreover, as a polishing pad, what has a porous resin layer called a nap layer may be used.

  The polishing slurry contains abrasive particles and a dispersion medium. The abrasive particles are made of, for example, colloidal silica or cerium oxide. As the dispersion medium, water, an organic solvent, or the like is used. The polishing slurry is supplied between the polishing pad and the glass plate 20.

  As the polishing slurry, one containing cerium oxide first may be used, and then one containing colloidal silica may be used.

  The average particle diameter of cerium oxide is preferably 0.1 μm to 5 μm from the viewpoints of surface roughness, undulation, polishing efficiency, and the like of the main surface of the glass plate 20 after polishing. The Asker C hardness of the polishing pad used together with the polishing slurry containing cerium oxide is preferably 60 or more, and preferably 100 or less from the viewpoint of the flatness of the entire glass plate 20 after polishing. The amount of polishing by the polishing slurry containing cerium oxide is preferably 1 μm or more. By this polishing, the waviness of the main surface of the glass plate 20 can be generally corrected.

  The average particle size of the colloidal silica is preferably 10 nm to 80 nm from the viewpoint of the surface roughness, undulation, polishing efficiency, etc. of the glass plate 20 after polishing. The pH of the polishing slurry containing colloidal silica is preferably less than 7, more preferably less than 6 and even more preferably less than 5 in order to avoid unintended chemical erosion between the end of polishing and cleaning. For pH adjustment, the polishing slurry may contain an inorganic acid and / or an organic acid. Examples of inorganic acids include nitric acid, sulfuric acid, hydrochloric acid, perchloric acid, phosphoric acid and the like. Of these inorganic acids, nitric acid is preferably used. Examples of the organic acid include oxalic acid and citric acid. The Asker C hardness of the polishing pad used together with the polishing slurry containing colloidal silica is preferably 60 or more, and preferably 100 or less from the viewpoint of generated surface scratches. The amount of polishing by the polishing slurry containing colloidal silica is preferably 100 nm or more. By this polishing, the surface roughness and waviness of the main surface of the glass plate 20 can be reduced.

  During the main surface polishing step S11 or after the main surface polishing step S11, a cleaning step is performed as necessary. In the cleaning process, foreign matters such as abrasive particles and dispersion medium adhering to the glass plate 20 are removed.

  In the cleaning process, various chemical solutions are used in addition to a rinse solution such as pure water or IPA (isopropyl alcohol). The chemical solution may be one generally used for cleaning a semiconductor substrate or a glass substrate. Specifically, a mixed solution of ammonia and hydrogen peroxide solution called APM, a mixed solution of hydrochloric acid and hydrogen peroxide solution called HPM, a mixed solution of sulfuric acid and hydrogen peroxide solution called SPM, dilute hydrofluoric acid called DHF (HF concentration of about 1 to 2% by mass), fluorinated nitric acid, alkaline cleaning liquid, and the like are used.

Cleaning conditions such as the type and concentration of the cleaning liquid and the cleaning time are selected in advance by a test or the like so that the magnitude of the maximum height difference in the X direction and the Y direction does not deteriorate. In selecting cleaning conditions, productivity and the like are also taken into consideration. Moreover, when ultrasonic cleaning is performed, the frequency of the ultrasonic wave is set within a range of 28 kHz to 3000 kHz, for example. When the ultrasonic frequency is within the above range, the glass surface is less damaged by ultrasonic cleaning, and the productivity (cleaning efficiency) is good.

  A local processing step may be performed during the main surface polishing step S11 or after the main surface polishing step S11. In the local processing step, the first main surface 21 of the glass plate 20 is processed locally. In the local processing step, the first main surface 21 and the second main surface 22 may be processed in order. The order is not particularly limited, and either may be processed first.

  In the local processing step, for example, an ion beam etching method, a gas cluster ion beam (GCIB) etching method, a plasma etching method, a wet etching method, a polishing method using a magnetic fluid, or a polishing method using a rotary polishing tool is used.

  In the non-through hole forming step S <b> 12, the non-through hole 24 is formed in the central portion of the second main surface 22 of the glass plate 20 as shown in FIG. 17. A processing tool 50 is used to form the non-through hole 24. At this time, the first main surface 21 of the glass plate 20 may be fixed to the processing table 70 via the protective film 60. Generation | occurrence | production of the damage | wound etc. by the contact with the glass plate 20 and the process table 70 can be prevented, and the deterioration of the magnitude | size of the maximum height difference in a X direction or a Y direction can be suppressed.

  The material of the protective film 60 may be either inorganic or organic. The inorganic substance may be a metal or a metal compound. The organic substance may be a resist, an adhesive resin sheet, or a double-sided adhesive resin sheet. Further, the protective film 60 may be a combination of these plural materials. As the material of the protective film 60, a general etching mask material may be used. For example, metal chromium, a metal chromium compound, a resist, or the like may be used. The protective film 60 is desirably one that can be removed without causing changes such as scratches and corrosion (etching) on the glass plate 20.

  The protective film 60 may protect the formation region of the projecting surface 23 from etching in the projecting surface forming step S13. The protective film 60 can be used to form the protruding surface 23, and the number of steps can be reduced.

  The grinding condition of the processing tool 50 is selected in advance by a test or the like so that the magnitude of the maximum height difference in the X direction and the Y direction does not deteriorate. In selecting the grinding conditions, productivity and the like are also taken into consideration. As the processing in the depth direction progresses, the distance between the processing tool 50 and the first main surface 21 becomes narrower, so the grinding speed in the depth direction may be set slower so that the first main surface 21 is not damaged. .

  The non-through hole forming step S12 includes a grinding step. When the grinding process includes a plurality of processes having different grinding conditions, the grinding speed in the depth direction in the final process is set to, for example, 100 μm / min or less.

  The non-through hole forming step S12 includes a polishing step after the grinding step. When the polishing step includes a plurality of steps having different polishing conditions, the polishing rate in the depth direction in the final step is set to, for example, 7 μm / min or less.

  In this embodiment, the non-through hole 24 is formed in the second main surface 22 of the glass plate 20, but the non-through hole 24 may not be formed in the second main surface 22 of the glass plate 20. The non-through hole 24 may not be provided.

  In the projecting surface forming step S13, the periphery of the first main surface 21 of the glass plate 20 is dug down as shown in FIG. 18, so that the periphery is surrounded by a step at the center of the first main surface 21 and protrudes from the periphery. A protruding surface 23 called a mesa is formed. Etching or the like is used as a method for digging up the outer peripheral portion of the first main surface 21. Etching may be either dry etching or wet etching.

  The etching conditions for digging the outer peripheral portion of the first main surface 21 (for example, the film thickness of the protective film 60) are selected in advance by testing or the like so that the magnitude of the maximum height difference in the X direction and the Y direction does not deteriorate. In selecting the etching conditions, productivity and the like are taken into consideration.

  After the outer peripheral portion of the first main surface 21 is dug down, the protective film 60 is removed. After the use of an etchant such as cerium (IV) ammonium oxalate, washing with an acidic solution such as hydrochloric acid having a pH of 1.8 or less may be performed. Thereby, precipitation of insoluble compounds such as cerium contained in the etchant can be suppressed, and deterioration of the maximum height difference in the X direction and the Y direction can be suppressed.

  In Test Examples 1 and 2, glass plates having different waviness of the protruding surface were produced, and the influence of CDU due to the waviness of the protruding surface was examined. Test Example 1 is an example, and Test Example 2 is a comparative example.

[Production of glass plate]
In Test Example 1 and Test Example 2, glass plates were produced under the same conditions except for the following conditions.

<Non-through hole forming step S12>
In Test Example 1, a 200 nm thick CrO film was used as the protective film 60, the final grinding speed in the grinding process was 5 μm / min, and the final polishing speed in the polishing process was 3 μm / min.
In Test Example 2, a 50 nm thick CrO film was used as the protective film 60, the final grinding speed in the grinding process was 110 μm / min, and the final polishing speed in the polishing process was 10 μm / min.

<Projection surface forming step S13>
In Test Example 1, a CrO / CrN multilayer film having a thickness of 100 nm was used as the protective film 60, and hydrochloric acid having a pH of 1.3 was used as a cleaning liquid after using the etchant. The CrO film used as the protective film 60 in the non-through hole forming step S12 was removed before forming the CrO / CrN multilayer film.
In Test Example 2, a CrO / CrN multilayer film having a thickness of 50 nm was used as the protective film 60, and hydrochloric acid having a pH of 5 was used as a cleaning liquid after using the etchant. The CrO film used as the protective film 60 in the non-through hole forming step S12 was removed before forming the CrO / CrN multilayer film.

[Measure the waviness of the protruding surface of the glass plate]
The waviness of the protruding surface of the glass plate produced in Test Examples 1 and 2 was measured by a scanning white interference method. The waviness of the protruding surface was measured from one end of the measurement region to the other end of the measurement region in the X direction. Table 1 shows the maximum height difference of the frequency components in the wavelength range of 50 μm or more and 50 mm or less among the waviness. In addition, the measurement of the waviness of the protruding surface was performed a plurality of times while changing the position in the Y direction so as to cover the entire measurement region. The “size of the maximum height difference” shown in Table 1 is the maximum value among a plurality of measurements.

[Formation of concavo-convex pattern on protruding surface of glass plate]
In Test Examples 1 and 2, an uneven pattern called line and space was formed on the protruding surface of the glass plate by the same method. The line-and-space line was perpendicular to the X direction and parallel to the Y direction.

The concavo-convex pattern on the protruding surface of the glass plate includes (1) film formation of an etching protective film, (2) film formation of a resist film, exposure and development, (3) dry etching with chlorine gas, and (4) CF ₄ system. It was formed by dry etching with gas.

  (1) The etching protective film was formed on the protruding surface of the glass plate by sputtering. The thickness of the etching protective film was 3 nm, and the material of the etching protective film was Cr nitride.

  (2) The resist film was formed by applying a resist material on the etching protective film by a spin coating method and baking the applied resist material. The resist film was partially exposed and developed by an electron beam drawing apparatus. Thereby, a resist film having an opening pattern was obtained.

  (3) Dry etching using a chlorine-based gas was used for processing an etching protective film partially protected by a resist film. Thus, an etching protective film having the same opening pattern as that of the resist film was obtained. Thereafter, the resist film that became unnecessary was removed.

(4) Dry etching with CF ₄ gas was used for processing the protruding surface of the glass plate partially protected by the etching protective film. Thereby, the uneven | corrugated pattern was formed in the protrusion surface of the glass plate. Thereafter, the etching protective film which became unnecessary was removed.

  The obtained concavo-convex pattern had a convex portion width of 15 nm, a convex portion pitch in the X direction of 30 nm, and a convex portion height of 25 nm.

[Transfer of uneven pattern]
In Test Examples 1 and 2, the concavo-convex pattern of the glass plate was transferred to the photocurable resin applied on the Si wafer by the same method, and then formed between the convex portion of the concavo-convex pattern of the glass plate and the Si wafer. The remaining film was removed.

  In order to improve the adhesiveness of the photocurable resin, the surface modification treatment was performed on the application surface of the photocurable resin on the Si wafer in advance. A silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBM-5103) was used for the surface modification treatment.

  The photocurable resin was applied by spin coating to the surface of the Si wafer that had been subjected to the surface modification treatment. As the photocurable resin, a fluorine-based UV curable resin (Asahi Glass Co., Ltd., trade name: NIF-A-2) was used.

  The residual film was removed by dry etching in which the entire photocurable resin film was exposed to oxygen plasma. Thereby, the test piece which consists of a film | membrane of the photocurable resin which has an opening pattern called a line and space, and Si wafer was obtained.

  The line width (width of the convex portion) of the photocurable resin film was determined by observing the fracture surface of the test piece with a CD-SEM (Critical Dimension-Scanning Electron Microscope). A W film was formed in advance on the fracture surface.

  CDU measured the width | variety of 30 convex parts, and computed it as a value 3 times the standard deviation (sigma) of the measured value. CDU was evaluated in three stages, “A”, “B”, and “C”. “A” indicates that the CDU is 2.0 or less, “B” indicates that the CDU is greater than 2.0 and is 2.3 or less, and “C” indicates that the CDU is greater than 2.3. means.

[Test results]
Table 1 shows the test results together with the conditions for producing the glass plate. In Table 1, only the differences between Test Example 1 and Test Example 2 are shown as the glass plate production conditions. In Table 1, “final grinding speed” means the grinding speed of the final process in the grinding process, and “final polishing speed” means the polishing speed of the final process in the grinding process.

表１から明らかなように、試験例１では、ガラス板の作製時に突出面を十分に保護していたため、突出面のうねりのうちの５０μｍ以上５０ｍｍ以下の波長範囲の周波数成分の最大高低差の大きさが１０ｎｍ以下であり、ＣＤＵの評価が「Ａ」であった。一方、試験例２では、ガラス板の作製時に突出面を十分に保護していなかったため、突出面のうねりのうちの５０μｍ以上５０ｍｍ以下の波長範囲の周波数成分の最大高低差の大きさが１０ｎｍを超え、ＣＤＵの評価が「Ｃ」であった。

As is clear from Table 1, in Test Example 1, since the protruding surface was sufficiently protected during the production of the glass plate, the maximum height difference of the frequency components in the wavelength range of 50 μm to 50 mm of the waviness of the protruding surface was The size was 10 nm or less, and the CDU evaluation was “A”. On the other hand, in Test Example 2, since the protruding surface was not sufficiently protected during the production of the glass plate, the maximum height difference of the frequency component in the wavelength range of 50 μm or more and 50 mm or less of the waviness of the protruding surface was 10 nm. The CDU rating was “C”.

  As mentioned above, although embodiment of the glass plate for imprint molds, etc. was described, the present invention is not limited to the above-mentioned embodiment etc., and within the scope of the gist of the present invention described in the claims, various modifications, Improvements are possible.

DESCRIPTION OF SYMBOLS 10 Mold 11 1st main surface 12 2nd main surface 13 Projection surface 14 Non-through-hole 15 Substrate 17 Transfer material 20 Glass plate 21 First main surface 22 Second main surface 23 Projection surface 24 Non-through-hole 24a Opening edge

Claims (5)

On one main surface, a glass plate for imprint mold having a substantially rectangular protruding surface that is surrounded by a step and protrudes from the periphery,
Measured from one end of the region to the other end of the region in a direction substantially parallel to one side of the region in a substantially rectangular region excluding a portion within 1.5 mm from the outer peripheral edge of the projecting surface. The glass plate for imprint molds in which the magnitude of the maximum height difference of the frequency component in the wavelength range of 50 μm or more and 50 mm or less among the undulations in the region is 10 nm or less.   In the region, of the undulation of the region measured from one end of the region to the other end of the region in a direction parallel to one side of the region, the maximum height difference of the frequency component in the wavelength range of 50 μm to 50 mm The glass plate for imprint molds according to claim 1, wherein the size is 7 nm or less.   The glass plate for imprint molds of Claim 1 or 2 which has a non-through-hole of predetermined depth in the main surface on the opposite side to the main surface in which the said protrusion surface is formed. The glass plate for imprint molds according to any one of claims 1 to 3,
The laminated board for imprint molds which has an etching protective film used for formation of the uneven | corrugated pattern in the said protrusion surface. It has the glass plate for imprint molds of any one of Claims 1-3,
An imprint mold having an uneven pattern on the protruding surface.

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