JP5123349B2 - Multi-tone mask manufacturing method - Google Patents

Description

  The present invention relates to a method of manufacturing a multi-tone mask used for manufacturing an FPD (flat panel display) device such as a liquid crystal display (hereinafter referred to as LCD), a plasma display, an organic EL display, and the like. The present invention relates to an etching apparatus used in a method for manufacturing a gradation mask.

  At present, in the field of FPD, especially in the field of LCD, thin film transistor liquid crystal display (hereinafter referred to as TFT-LCD) is a current product due to the advantage of being thin and easy to consume. The process is progressing rapidly. A TFT-LCD includes a TFT substrate having a structure in which TFTs are arranged in pixels arranged in a matrix, and a color filter in which red, green, and blue pixel patterns are arranged corresponding to each pixel. It has a schematic structure superimposed under the intervention of. In TFT-LCD, the number of manufacturing processes is large, and the TFT substrate alone is manufactured using 5 to 6 photomasks. Under such circumstances, a method for manufacturing a TFT substrate using a smaller number of photomasks has been proposed.

  In this method, the number of masks to be used is reduced by using a photomask having a light shielding portion, a light transmitting portion, and a semi-light transmitting portion. Here, the semi-transparent portion means that when a pattern is transferred to a transfer object using a mask, the amount of exposure light transmitted therethrough is reduced by a predetermined amount, and the photoresist film on the transfer object after development is developed. A portion that controls the amount of remaining film is referred to, and a photomask having such a semi-transparent portion together with a light-shielding portion and a translucent portion is generally called a gray tone mask. By using a gray tone mask having a semi-translucent portion having a predetermined exposure light transmittance together with a light-shielding portion and a translucent portion, the remaining film values of three gradations are different in the photoresist on the transfer target. A desired transfer pattern including a portion can be formed, and more by using a gray-tone mask having a plurality of semi-transparent portions having different exposure light transmittances together with a light-shielding portion and a translucent portion. Since a transfer pattern having four or more gradations can be formed, such a gray tone mask is referred to as a “multi-tone mask” in the present invention.

  By the way, a multi-tone mask having a structure in which the semi-translucent portion is formed with a fine pattern below the resolution limit of an exposure machine using the multi-tone mask is known. In many cases, the resolution limit of an exposure device using a multi-tone mask is about 3 μm for a stepper type exposure device and about 4 μm for a mirror projection type exposure device. However, such a semi-transparent part of the fine pattern type is designed to produce a semi-transparent part, specifically, a fine pattern for providing a halftone effect intermediate between the light-shielding part and the translucent part. -There is a choice between a space type, a dot (halftone dot) type, or another pattern, and in the case of the line and space type, how much the line width should be, The design must be made in consideration of a great number of things, such as what should be done with the ratio of the light-shielded portion and how much the overall transmittance should be designed. Also in the mask manufacturing, extremely difficult production techniques such as management of the center value of the line width and management of variation in the line width within the mask have been required.

  Therefore, it has been conventionally proposed to form the semi-translucent portion by a semi-translucent film that is translucent. By using this semi-transparent film, exposure can be performed while reducing the exposure amount in the semi-translucent portion. When using a semi-transparent film, consider how much the overall transmittance is necessary in the design, and in the mask, select the film type (material) of the semi-translucent film or select the film thickness to produce the mask. It becomes possible. Therefore, in the manufacture of the multi-tone mask, it is sufficient to control the thickness of the semi-translucent film, and the management is relatively easy. For example, when the TFT channel portion is formed by a semi-transparent portion of a multi-tone mask, a semi-transparent film can be easily patterned by a photolithography process. There is also an advantage that a highly accurate pattern can be formed.

  When the semi-transparent portion of the multi-tone mask is formed of a semi-transparent film, a metal silicide compound such as molybdenum is widely known as a material of the semi-transparent film. As materials for the semi-transparent film other than the metal silicide compound, for example, materials mainly composed of tantalum have been conventionally proposed (Patent Documents 1 and 2). In particular, tantalum-based materials are easy to adjust the exposure light transmittance by adjusting the film thickness, and can be used for multicolor exposure using an ultra-high pressure mercury lamp widely used in FPD exposure machines as a light source. There are advantages such as a small change in transmittance with respect to a change in wavelength in the wavelength range from the i-line to the g-line that is the exposure wavelength band (small wavelength dependence and flat spectral characteristics).

  The multi-tone mask includes, for example, a translucent film made of a material mainly containing metal silicide or tantalum and a light-shielding film made of a material mainly made of chromium on a light-transmitting substrate such as synthetic quartz glass. Using the mask blanks laminated in this order, the light-shielding film and the semi-translucent film are respectively patterned as desired to produce a transfer pattern composed of the light-shielding part, the translucent part, and the semi-translucent part.

JP 2008-249950 A JP 2002-196473 A

  In the above multi-tone mask manufacturing method, the light-shielding film is etched by using the resist film having the pattern of the light-transmitting portion formed on the light-shielding film of the mask blank as a mask. Forming a light-transmitting part by exposing the surface of the light-transmitting substrate by etching the semi-light-transmitting film using the pattern of the light-transmitting part formed on the light shielding film as a mask. And a step of forming a light shielding portion pattern on the light shielding film by etching the light shielding film using a resist film having a light shielding portion pattern formed on the light shielding film as a mask.

  Although the etching process can be performed by so-called wet etching or dry etching, the substrate size of a multi-tone mask used for manufacturing the FPD device has been increased with the recent trend of increasing the size of the FPD device. Therefore, it is necessary to generate plasma when trying to perform dry etching when manufacturing a large mask. Therefore, it is necessary to generate plasma on the entire main surface of a large mask blank that is very large compared to LSI applications. A plasma generator capable of generating plasma is required, and a very expensive dry etching apparatus must be introduced. In view of production cost, the dry etching method has become impractical.

  On the other hand, the wet etching does not cause such a problem. As the etching solution for the light-shielding film made of a material containing chromium as a main component, an etching solution containing ceric ammonium nitrate and perchloric acid is usually used. In addition, as an etching solution for the semi-transparent film made of a material mainly containing metal silicide, for example, an etching solution containing ammonium hydrogen fluoride and hydrogen peroxide is used. Further, as an etching solution for a semi-transparent film made of a material mainly composed of tantalum, an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide heated to 50 ° C. or higher is used.

  According to the inventor's study, in the case of a semi-transparent film made of a material containing tantalum as a main component, the etching rate with respect to the alkaline aqueous solution is not so large, so the semi-transparent film is removed by wet etching using the alkaline aqueous solution. Then, it turned out that a big problem generate | occur | produces as a multi-tone mask that a pit-shaped recessed part will be formed in the exposed glass substrate surface.

  Since the translucent part of the multi-tone mask is formed by wet etching that exposes the surface of the glass substrate, if pit-shaped recesses are generated on the glass substrate surface constituting the translucent part, the transmittance is greatly reduced. End up. Since the etching time varies depending on the ease of etching of the pattern shape for etching the semi-transparent film, it is difficult to suppress the formation of pit-shaped recesses even if the etching time is adjusted strictly. When such a multi-tone mask is used to expose and transfer the pattern onto the photoresist film of the transfer target, there is a problem that the accuracy of the remaining film amount control after developing the photoresist film is low.

  On the other hand, in the case of a semi-transparent film made of a material containing metal silicide as a main component, there is no problem that a pit-shaped recess is generated on the glass substrate surface. However, the miniaturization of the pattern formed on the semi-transparent film is progressing, and the in-plane roughness difference between the resist pattern and the light shielding film pattern is increasing. At the time of etching the semi-transparent film, the etchant tends to be easily replaced in a sparse pattern portion, and the etching rate tends to be fast. In the dense pattern portion, the etchant is difficult to replace and the etching rate tends to be slow. This difference greatly affects the in-CD uniformity of the semi-transparent film pattern after etching. In particular, in the case of wet etching, there is a problem that in a dense pattern, the replacement of the etching solution is poor as compared with the etching gas for dry etching, and the CD in-plane uniformity of the semi-translucent film tends to be low.

  On the other hand, as a metal material applied to the semi-transparent film of the multi-tone mask, in addition to tantalum, hafnium (Hf), zirconium (Zr), tungsten (W), zinc (Zn), molybdenum (Mo), titanium ( Ti), vanadium (V), yttrium (Y), rhodium (Rh), niobium (Nb), lanthanum (La), palladium (Pd), iron (Fe), aluminum (Al), germanium (Ge), tin ( Sn) and the like have been studied so far. As an etching solution for wet-etching the semi-transparent film of these metal materials, an alkaline aqueous solution or the like has been studied. However, as in the case of tantalum, sufficient etching selectivity with a translucent substrate is obtained. Is difficult. In addition, there is also a problem that it is difficult to say that the in-CD uniformity of the semi-transparent film is good.

In recent years, competition for lowering the price of FPD devices has become more severe, and it has become an important issue to reduce the manufacturing cost of multi-tone masks. Against this background, a pattern defect that is difficult to correct in a multi-tone mask manufactured using a mask blank was found. The multi-tone mask was peeled off from the substrate without being discarded as a defective product. There is a need for a method of removing and recycling the substrate.
In order to completely remove the damage generated on the surface of the substrate and regenerate the substrate, it is necessary to re-polish and take a lot of polishing allowance. Surface polishing of a glass substrate before film formation is usually performed through a plurality of stages of polishing steps from rough polishing to precision polishing. When re-polishing, since it is necessary to take a lot of polishing allowance as described above, it is necessary to return to the initial stage of the multi-step polishing process, and the re-polishing process takes a long time, so the re-polishing process load Is large and the cost is high. In other words, when a multi-tone mask is manufactured by a manufacturing method including a step of performing wet etching using an alkaline aqueous solution on a semi-transparent film made of a material containing tantalum as a main component, the obtained mask is corrected. It is costly to regenerate the substrate by stripping and removing the light-shielding film and the semi-transparent film from the substrate with the etching solution without discarding the mask in which a difficult pattern defect is found as a defective product. End up.

  Further, even when the substrate is reproduced from a multi-tone mask having a semi-transparent film made of a material mainly composed of metal and silicon, the flatness of the substrate peeled off by the etching solution is unavoidable, Since it is necessary to make a lot of polishing allowance for correcting the flatness, it is costly to regenerate the substrate.

  Therefore, the present invention has been made in view of such various problems of the prior art, and the object of the present invention is to provide a pattern on a semi-transparent film without requiring a large and very expensive dry etching apparatus. The CD in-plane uniformity when formed is higher than that in the case of wet etching, and the re-grinding process load when the substrate is regenerated can reduce the regeneration cost of the substrate. In particular, tantalum is the main component. In the case of a semi-transparent film, a multi-tone mask manufacturing method capable of suppressing the formation of pit-shaped recesses on the substrate surface at the mask manufacturing stage, and an etching apparatus used in the multi-tone mask manufacturing method Is to provide.

  As a result of intensive studies to solve the above problems, the present inventor has found a material containing metal and silicon, or tantalum (Ta), hafnium (Hf), zirconium (Zr), tungsten (W), zinc (Zn). , Molybdenum (Mo), titanium (Ti), vanadium (V), yttrium (Y), rhodium (Rh), niobium (Nb), lanthanum (La), palladium (Pd), iron (Fe), aluminum (Al) When etching a semi-transparent film made of a material containing one or more metals selected from germanium (Ge) and tin (Sn), specific fluorine compounds, that is, chlorine (Cl), bromine (Br), iodine A non-compound containing a compound of any one of (I) and xenon (Xe) and fluorine (F) (hereinafter referred to as a fluorine-based compound of the present invention). By using the material of the raised state, than in the case of wet etching it has been found that it is possible to increase the CD-plane uniformity of the semi-transparent film pattern after etching. In particular, when etching a semi-transparent film made of a material containing tantalum, by using a non-excited substance containing the fluorine-based compound of the present invention, the semi-transparent film is removed by etching. It has been found that the occurrence of pit-like concave defects on the surface of the substrate can be suppressed.

The present inventor completed the present invention as a result of further intensive studies based on the above elucidated facts.
That is, in order to solve the above problems, the present invention has the following configuration.
(Configuration 1)
In a method for manufacturing a multi-tone mask having a light-transmitting portion, a light-transmitting portion, and a semi-transparent portion that transmits part of exposure light on a light-transmitting substrate, a metal is formed on the light-transmitting substrate. And silicon-containing material, or tantalum (Ta), hafnium (Hf), zirconium (Zr), tungsten (W), zinc (Zn), molybdenum (Mo), titanium (Ti), vanadium (V), yttrium ( One or more metals selected from Y), rhodium (Rh), niobium (Nb), lanthanum (La), palladium (Pd), iron (Fe), aluminum (Al), germanium (Ge) and tin (Sn) A step of preparing a mask blank in which a semi-transparent film made of a material containing and a light-shielding film made of a material containing chromium (Cr) are laminated in this order; and Using the step of forming a turn and the pattern of the light-transmitting portion formed on the light-shielding film as a mask, the semi-light-transmitting film is made into chlorine (Cl), bromine (Br), iodine (I), and xenon (Xe). A step of etching with a non-excited substance containing a compound of any one of the above elements and fluorine (F), and a step of forming a pattern of a light shielding part on the light shielding film. It is a manufacturing method of a tone mask.
(Configuration 2)
The process of forming a light-transmitting part pattern on the light-shielding film is performed by wet etching using a resist film having a light-transmitting part pattern formed on the light-shielding film as a mask. It is a manufacturing method of a multi-tone mask.

(Configuration 3)
In a method for manufacturing a multi-tone mask having a light-transmitting portion, a light-transmitting portion, and a semi-transparent portion that transmits part of exposure light on a light-transmitting substrate, a metal is formed on the light-transmitting substrate. And silicon-containing material, or tantalum (Ta), hafnium (Hf), zirconium (Zr), tungsten (W), zinc (Zn), molybdenum (Mo), titanium (Ti), vanadium (V), yttrium ( One or more metals selected from Y), rhodium (Rh), niobium (Nb), lanthanum (La), palladium (Pd), iron (Fe), aluminum (Al), germanium (Ge) and tin (Sn) A step of preparing a mask blank in which a semi-transparent film made of a contained material and a light shielding film made of a material containing chromium (Cr) are laminated in this order; A step of forming a turn, a step of forming a resist film having a light-transmitting portion pattern on the light-shielding film and the semi-light-transmitting film, and the pattern of the light-transmitting portion formed in the resist film as a mask. The light-transmitting film is etched with a non-excited substance containing a compound of any element of chlorine (Cl), bromine (Br), iodine (I), and xenon (Xe) and fluorine (F). And a process for producing a multi-tone mask.

(Configuration 4)
The step of forming a light shielding portion pattern on the light shielding film is performed by wet etching using a resist film having a light shielding portion pattern formed on the light shielding film as a mask. It is a manufacturing method of the multi-tone mask of one term.

(Configuration 5)
5. The multi-tone mask manufacturing method according to any one of Structures 1 to 4, wherein the non-excited substance is ClF ₃ gas.
(Configuration 6)
6. The multi-tone mask manufacturing method according to any one of Structures 1 to 5, wherein the metal in the semi-transparent film is molybdenum (Mo).

(Configuration 7)
The multi-tone mask manufacturing method according to any one of Structures 1 to 6, wherein the light shielding film is made of a material further containing nitrogen.
(Configuration 8)
The multi-tone mask manufacturing method according to any one of Structures 1 to 7, wherein the translucent substrate is made of synthetic quartz glass.
(Configuration 9)
An etching apparatus used in the method for manufacturing a multi-tone mask according to any one of Structures 1 to 8, wherein a chamber having a stage on which the mask blank is placed and a non-excited substance is supplied into the chamber An etching apparatus comprising: a non-excited substance supply machine; and a gas discharge machine for discharging gas from the chamber.

According to the method for manufacturing a multi-tone mask of the present invention, a material containing metal and silicon, or tantalum (Ta), hafnium (Hf), zirconium (Zr), tungsten (W), zinc (Zn), molybdenum ( Mo), titanium (Ti), vanadium (V), yttrium (Y), rhodium (Rh), niobium (Nb), lanthanum (La), palladium (Pd), iron (Fe), aluminum (Al), germanium ( A semi-transparent film made of a material containing one or more metals selected from Ge) and tin (Sn) has a high etching rate with respect to a non-excited substance containing the fluorine-based compound of the present invention, and is translucent. Glass, which is the material of the substrate, has a significantly low etching rate with respect to this non-excited fluorine-based compound material, and is a semi-translucent material made of a material containing the metal. High etch selectivity is obtained between the. As a result, when the multi-tone mask is manufactured by etching away the semi-transparent film of the portion that becomes the translucent portion of the multi-tone mask with this non-excited fluorine-based compound substance, CD in-plane uniformity can be improved as compared with wet etching.
In particular, in the case of a semi-transparent film made of a material containing tantalum, pit-shaped concave defects generated on the substrate surface after the semi-transparent film is removed by etching can be suppressed. This makes it possible to increase the in-plane uniformity of the exposure light transmittance of the light-transmitting portion, and develop the photoresist film when the pattern is exposed and transferred to the photoresist film of the transfer object using this multi-tone mask. The amount of remaining film can be controlled with high accuracy.
According to the present invention, etching using a non-excited substance containing a fluorine-based compound is applied, so that the chamber in which etching is performed functions sufficiently if the pressure in the chamber can be reduced to a certain level. For this reason, a large chamber for high vacuum such as a dry etching apparatus and a large-scale plasma generation apparatus for generating plasma over the entire main surface of the substrate are not required, and the production cost can be greatly reduced. Further, since a high-quality substrate can be reproduced at a low cost, it is particularly suitable for the reproduction of a multi-tone mask substrate using an expensive base material with high added value.
Furthermore, by using the etching apparatus of the present invention, the above multi-tone mask manufacturing method can be easily realized.

It is a schematic sectional drawing for demonstrating the pattern transfer method using a multi-tone mask. It is a schematic sectional drawing which shows the manufacturing process of a multi-tone mask. It is a schematic sectional drawing which shows another form of the manufacturing process of a multi-tone mask. It is a schematic block diagram of the etching apparatus used for the etching process of a semi-translucent film.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is a schematic cross-sectional view for explaining a pattern transfer method using a multi-tone mask. The multi-tone mask 20 of the present invention shown in FIG. 1 is used for manufacturing an FPD device such as a thin film transistor (TFT) or a color filter of a liquid crystal display device (LCD) or a plasma display panel (PDP). A resist pattern 33 having different film thicknesses is formed stepwise or continuously by performing pattern transfer onto the transfer target 30 shown in FIG. 1 using the multi-tone mask 20. In FIG. 1, reference numerals 32 </ b> A and 32 </ b> B denote films stacked on the substrate 31 in the transfer target 30.

  Specifically, the multi-tone mask 20 exposes the light-shielding portion 21 that shields the exposure light (transmittance is approximately 0%) and the surface of the translucent substrate 1 when the multi-tone mask 20 is used. A translucent portion 22 that transmits exposure light, and a semi-translucent portion 23 that reduces the transmittance to 10 to 80%, preferably about 20 to 60% when the exposure light transmittance of the translucent portion is 100%. It is configured. The translucent part 23 is configured by forming a translucent semi-transparent film 2 on a translucent substrate 1 such as a glass substrate. The light shielding part 21 is configured by laminating the semi-transparent film 2 and the light shielding film 3 on the light transmissive substrate 1. Note that the pattern shapes of the light shielding portion 21, the light transmitting portion 22, and the semi-light transmitting portion 23 shown in FIG. 1 are merely representative examples, and it is needless to say that the present invention is not limited thereto.

In the present invention, the translucent film 2 is made of a material containing metal and silicon (Si), or tantalum (Ta), hafnium (Hf), zirconium (Zr), tungsten (W), zinc (Zn). , Molybdenum (Mo), titanium (Ti), vanadium (V), yttrium (Y), rhodium (Rh), niobium (Nb), lanthanum (La), palladium (Pd), iron (Fe), aluminum (Al) In addition, a material containing one or more metals selected from germanium (Ge) and tin (Sn) is used, and the light shielding film 3 is made of a material containing chromium (Cr).
The light-shielding portion 21 preferably has an optical density (OD) in a laminated structure of the light-shielding film 3 and the semi-transparent film 2 by selecting the film materials and film thicknesses of the light-shielding film 3 and the semi-transparent film 2. 2.8 or more (transmittance to exposure light is about 0.16% or less). Further, it is optimal that the optical density (OD) in the laminated structure of the light shielding film 3 and the semi-transparent film 2 is set to 3.0 or more (transmittance for exposure light is 0.1% or less). The transmittance of the semi-translucent portion 23 is set by selecting the film material and the film thickness of the semi-transparent film 2.

  In the case where multi-color light from an ultra-high pressure mercury lamp is used as the light source as exposure light for exposure transfer using the multi-tone mask 20, the optical density and transmittance of the light shielding part 21, the semi-transparent part 23, etc. are as follows. And at least one of the peak wavelengths of exposure light, i-line (wavelength 365 nm), h-line (wavelength 405 nm), and g-line (wavelength 436 nm), so that the predetermined optical density and transmittance are adjusted. There is a need. Further, it is more desirable to adjust so as to satisfy a predetermined optical density and a predetermined range of transmittance at any wavelength of i-line, h-line, and g-line.

  When the multi-tone mask 20 as described above is used, the exposure light is not substantially transmitted through the light shielding portion 21 and the exposure light is reduced at the semi-transparent portion 23. The resist film (for example, a positive resist film) is thicker at the portion corresponding to the light-shielding portion 21 and is thinner at the portion corresponding to the semi-transparent portion 23 when developed after transfer. Thus, a three-tone resist pattern 33 in which a remaining film does not substantially occur in a portion corresponding to the light transmitting portion 22 is formed (see FIG. 1). In the resist pattern 33, the effect of reducing the film thickness at the portion corresponding to the semi-transparent portion 23 is called a gray tone effect. In the case where a negative resist is used, it is necessary to design in consideration that the resist film thickness corresponding to the light shielding portion and the light transmitting portion is reversed.

  Then, first etching is performed on, for example, the films 32A and 32B of the transfer target 30 in the portion where the resist pattern 33 shown in FIG. 1 is not formed, and the thin portion of the resist pattern 33 is removed by ashing or the like. Then, the second etching is performed on, for example, the film 32 </ b> B in the transfer target 30. In this way, a process for two conventional photomasks is performed using one multi-tone mask 20, and the number of masks is reduced.

  The multi-tone mask 20 shown in FIG. 1 has a transfer pattern comprising a light-shielding portion 21, a light-transmitting portion 22, and one semi-transparent portion 23 having a predetermined exposure light transmittance on the light-transmitting substrate 1. However, if a plurality of semi-transparent portions having different exposure light transmittances are provided together with the light-shielding portion and the light-transmitting portion, the mask can be further increased to four or more gradations.

Next, the manufacturing method of the multi-tone mask of this invention is demonstrated.
FIG. 2 is a schematic cross-sectional view showing the manufacturing process of the multi-tone mask in the order of steps.
In this embodiment, a three-tone mask provided with a light shielding portion, a light transmitting portion, and a semi-light transmitting portion as shown in FIG. 1 will be described as an example.
The mask blank 10 used in the present embodiment has a material containing metal and silicon (Si), tantalum (Ta), hafnium (Hf), zirconium (Zr), tungsten (W ), Zinc (Zn), molybdenum (Mo), titanium (Ti), vanadium (V), yttrium (Y), rhodium (Rh), niobium (Nb), lanthanum (La), palladium (Pd), iron (Fe) ), Aluminum (Al), germanium (Ge), and tin (Sn), a semi-transparent film 2 made of a material containing one or more metals, and a light-shielding film 3 made of a material containing chromium (Cr). The resist film 4 is formed by laminating in this order and applying a resist thereon (see FIG. 2A). In the present embodiment, the transmittance of the light-shielding portion in the manufactured three-tone mask is determined by the lamination of the light-shielding film 3 and the semi-transparent film 2, and by selecting the respective film materials and film thicknesses, The total sum is preferably set to an optical density of 2.8 or higher, and optimally set to 3.0 or higher. Further, the transmissivity of the semi-translucent portion in the three-tone mask is set by the selection of the film material and film thickness of the semi-transparent film 2, and usually depends on the required design value. When the exposure light transmittance is set to 100%, the transmittance is preferably set to about 10 to 80%, preferably about 20 to 60%.

  The translucent substrate 1 for the mask blank is not particularly limited as long as it is transparent to the exposure wavelength to be used, and is a synthetic quartz substrate or other various glass substrates (for example, soda lime glass, aluminosilicate). Among them, a synthetic quartz substrate is particularly preferably used. Moreover, the translucent substrate 1 used in the multi-tone mask blank generally has a side of 500 mm or more. At present, there are various sizes in which the short side × long side of the substrate is in the range of 500 mm × 800 mm to 2140 mm × 2460 mm, and the thickness is in the range of 10 mm to 15 mm.

  When a material containing a metal and silicon (Si) is used for the semi-transparent film 2, applicable metals include Mo, Hf, Zr, Ge, Sn, W, Zn, Ni, Y, Ti, and V. , Rh, Nb, La, Pd, Fe, Ge, Al and the like. In particular, when Mo, Hf, Zr, W, Ti, V, Nb, and Al are applied, the etching rate when the semi-transparent film is etched with a non-excited substance containing the fluorine-based compound of the present invention is increased. In addition, the wavelength dependency of the exposure light transmittance of the translucent film (especially the wavelength region of i-line to g-line) can be reduced, which is preferable. The ratio of metal (M) to silicon (Si) in the semi-transparent film 2 of these materials is preferably in the range of M: Si = 1: 2 to 1:19. The semi-transparent film 2 is more preferably a material containing a transition metal and silicon in order to form a transition metal silicide. In particular, molybdenum (Mo) is preferable among the transition metals. The ratio of molybdenum (Mo) to silicon (Si) in the semi-transparent film 2 made of a material containing molybdenum (Mo) and silicon (Si) in the semi-transparent film 2 is Mo: Si = 1: 2 to 1: A range of 19 is preferred.

  The translucent film 2 using a material containing metal and silicon (Si) may be a material further containing nitrogen. By containing nitrogen, the crystal grain size of the film is refined, the film stress is reduced, and the adhesiveness with the translucent substrate 1 is improved. When a material containing metal and silicon (Si) contains elements such as nitrogen and carbon, the content of these elements is preferably 40 atomic% or less, more preferably 30 atomic% or less. Thereby, the etching rate at the time of etching the semi-transparent film 2 with the non-excited substance containing the fluorine-based compound of the present invention can be increased.

  Tantalum (Ta), hafnium (Hf), zirconium (Zr), tungsten (W), zinc (Zn), molybdenum (Mo), titanium (Ti), vanadium (V), yttrium (Y ), Rhodium (Rh), niobium (Nb), lanthanum (La), palladium (Pd), iron (Fe), aluminum (Al), germanium (Ge) and tin (Sn) In addition to these simple metals and alloys, nitrides, oxides, oxynitrides, and the like of the simple metals and alloys can be used. Further, among the metals shown above, a single metal of Ta, Mo, Hf, Zr, W, Ti, V, Nb, or Al or an alloy of a metal selected from these metals is used for the semi-transparent film 2. When applied as a metal to be contained, it is preferable because the etching rate when the semi-transparent film 2 is etched with a non-excited substance containing the fluorine-based compound of the present invention can be further increased.

  In the present invention, a material containing tantalum (Ta) is particularly preferable as the material of the semi-transparent film 2. In addition to tantalum alone, tantalum nitride (TaN), tantalum oxide (TaO), tantalum oxynitride (TaNO), and the like can be given. In the present invention, a material containing tantalum and one or more elements selected from silicon and boron is also preferable. Specifically, as a material containing tantalum and silicon, TaSi, TaSiN, TaSiO, TaSiON, etc. As a material containing tantalum and boron, TaB, TaBN, TaBO, TaBON, etc. As a material containing tantalum, silicon, and boron, TaSiB , TaSiBN, TaSiBO, TaSiBON and the like.

  By containing boron in the tantalum-containing material, the wavelength dependency of the exposure light transmittance in the semi-transparent film (particularly, the wavelength range of i-line to g-line) is reduced. In this case, the boron content is preferably 40 atomic% or less.

  Moreover, when elements, such as nitrogen and carbon, are further contained in the material containing tantalum, the content of these elements is preferably 40 atomic% or less, more preferably 30 atomic% or less. Thereby, the etching rate at the time of etching the semi-transparent film 2 with the non-excited substance containing the fluorine-based compound of the present invention can be increased.

  The light-shielding film 3 is made of a material containing chromium (Cr). In addition to chromium alone, the light-shielding film 3 is made of a material containing elements such as nitrogen, oxygen, and carbon in chromium, for example, CrN, CrO, CrC, CrON, CrCN. , CrOC, CrOCN and the like. In particular, nitrogen is preferably contained in the material containing chromium. Nitrogen increases the etching rate for the etchant used when wet-shielding the light-shielding film, and when the light-shielding film is wet-etched using a resist film having a light-shielding portion pattern formed on the light-shielding film as a mask. In addition, the etching selectivity between the light shielding film and the semi-transparent film can be further enhanced, and damage to the semi-transparent film under the light shielding film can be further suppressed. When nitrogen is contained in the light-shielding film containing chromium, the nitrogen content is preferably in the range of 15 to 60 atomic%. When the nitrogen content is less than 15 atomic%, the above-described effects cannot be obtained sufficiently. On the other hand, when the content exceeds 60 atomic%, when an ultrahigh pressure mercury lamp is used as a light source for exposure light, it is necessary to increase the film thickness in order to obtain a predetermined optical density in the wavelength band from i-line to g-line. This causes a problem that the CD accuracy is lowered when forming the pattern of the light shielding portion. Further, the CD accuracy when the pattern of the semi-transparent portion is formed using the light shielding film as an etching mask is also lowered.

Next, a manufacturing process of a multi-tone (three-tone) mask using the mask blank 10 will be described.
First, drawing is performed for the first time. In the present embodiment, laser light (for example, light having a predetermined wavelength within a range of 400 to 450 nm) is used for drawing. A positive resist is used as the resist. A predetermined device pattern (a pattern of a light-transmitting portion, that is, a drawing pattern that forms a resist pattern in a region corresponding to the light-shielding portion and the semi-light-transmitting portion) is drawn on the resist film 4 on the light-shielding film 3. By performing development later, a resist pattern 4a having a pattern of a light transmitting portion is formed (see FIG. 2B).

  Next, the light-shielding film 3 is etched using the resist pattern 4a as a mask to expose the semi-transparent film 2 corresponding to the region of the light-transmitting part, and a pattern of the light-transmitting part is formed on the light-shielding film 3 ( (Refer FIG.2 (c)). When the light-shielding film 3 made of a material containing chromium is used, the etching means can be either dry etching or wet etching, but in this embodiment, wet etching is used. In particular, wet etching is suitable for manufacturing a mask having a large substrate size. As an etchant used for wet etching, for example, a mixed solution of ceric ammonium nitrate and perchloric acid is used. The remaining resist pattern 4a is removed (see FIG. 2D).

Next, the translucent film 2 on the exposed translucent part region is etched using the pattern of the translucent part formed on the light shielding film 3 as a mask to form a translucent part (see FIG. 2E). ).
In the etching process of the semi-transparent film 2, since the pattern of the translucent part formed in the light-shielding film 3 is used as an etching mask, the light-shielding film 3 and the semi-transparent light to the etchant used for etching the semi-transparent film 2 are used. In order to reduce the damage on the surface of the substrate (glass substrate) after the semi-transparent film 2 is removed, etching selectivity with the film 2 is necessary. Etching selectivity between the semi-transparent film 2 and the translucent substrate 1 with respect to the etchant used for the above is also required.

In the present invention, any one of chlorine (Cl), bromine (Br), iodine (I), and xenon (Xe) as an etchant used for etching the translucent film 2 and fluorine (F) It is characterized in that a non-excited substance including the above compound (referred to as the fluorine-based compound of the present invention) is applied.
For the non-excited fluorine compound of the present invention, the light-shielding film 3 made of a material containing chromium and a material containing metal and silicon, or tantalum (Ta), hafnium (Hf), zirconium ( Zr), tungsten (W), zinc (Zn), molybdenum (Mo), titanium (Ti), vanadium (V), yttrium (Y), rhodium (Rh), niobium (Nb), lanthanum (La), palladium ( High etching selectivity between the translucent film 2 made of a material containing one or more metals selected from Pd), iron (Fe), aluminum (Al), germanium (Ge) and tin (Sn) Can be obtained.
Further, the glass substrate used as the translucent substrate 1 is easily etched by the fluorine-based gas plasma in the excited state used in dry etching. It has a characteristic that it is difficult to be etched. Therefore, it is possible to obtain high etching selectivity between the glass substrate and the semi-transparent film 2 for the non-excited fluorine-based compound of the present invention.

As the fluorine compound of the present invention, for example, a compound such as ClF ₃ , ClF, BrF ₅ , BrF, IF ₃ , IF ₅ , or XeF ₂ can be preferably used. Of these, ClF ₃ can be particularly preferably used in the present invention.
The non-excited fluorine-based compound material is preferably brought into contact in a fluid state, and is preferably brought into contact in a gas state.

  In the etching step of the semi-transparent film 2, as a method of bringing the semi-transparent film 2 into contact with a non-excited substance containing the fluorine-based compound of the present invention, for example, a processing substrate (that is, FIG. The substrate in the state shown in FIG. 4 is referred to as a “processed substrate” for convenience of explanation.) Is installed, and a substance containing the fluorine-based compound of the present invention is introduced into the chamber in a gaseous state, A method of replacing with gas is preferred.

In the present invention, when the substance containing the fluorine compound of the present invention is used in a gas state, the fluorine compound of the present invention and nitrogen gas, or argon (Ar), helium (He), neon (Ne), krypton (Kr) ), Xenon (Xe), radon (Rn) and the like (hereinafter, simply referred to as argon (Ar) and the like) and a mixed gas can be preferably used.
The processing conditions when the semi-transparent film 2 of the processing substrate is brought into contact with the non-excited gaseous substance containing the fluorine compound of the present invention, for example, gas flow rate, gas pressure, temperature, and processing time must be particularly restricted. However, from the viewpoint of preferably obtaining the action of the present invention, it is desirable to select appropriately according to the materials and film thicknesses of the semi-translucent film and the light-shielding film.

  Regarding the gas flow rate, for example, when a mixed gas of the fluorine-based compound of the present invention and argon or the like is used, it is preferable that the fluorine-based compound of the present invention is mixed at a flow rate ratio of 1% or more. When the flow rate of the fluorine-based compound of the present invention is less than the above flow rate ratio, the progress of the etching of the semi-transparent film 2 is slowed, resulting in a longer processing time and a larger side etch amount.

  The gas pressure is preferably selected as appropriate in the range of 100 to 760 Torr, for example. If the gas pressure is lower than the above range, the gas amount of the fluorine-based compound of the present invention in the chamber is too small, and the progress of the etching of the semi-translucent film 2 is slowed. The amount increases. On the other hand, if the gas pressure is higher than the above range (above atmospheric pressure), the gas may flow out of the chamber, and the fluorine compound of the present invention includes highly toxic gas, which is not preferable. .

  Moreover, it is preferable to select suitably about the temperature of gas in the range of 50-250 degreeC, for example. When the temperature is lower than the above range, the progress of the etching of the semi-transparent film 2 is delayed, and as a result, the processing time becomes longer and the side etching amount becomes larger. On the other hand, if the temperature is higher than the above range, the etching progresses quickly and the processing time can be shortened, but it becomes difficult to obtain the selectivity between the semi-transparent film and the substrate, and the substrate damage may be slightly increased.

  Further, the processing time may be basically a time sufficient for completing the etching of the semi-transparent film 2. In the case of the present invention, the action of the present invention is preferably obtained in the range of approximately 20 seconds to 300 seconds, although it varies somewhat depending on the gas flow rate, gas pressure, and temperature described above or depending on the material and film thickness of the semi-translucent film. .

FIG. 4 is a schematic configuration diagram of an etching apparatus suitable for use in the above semi-transparent film etching process.
In this etching apparatus, the gas filling containers 43 and 44, the flow rate controllers 45 and 46, the ejection nozzle 47 and their connection pipes constitute a non-excited gas supply machine. A processing substrate (mask blank) 41 is placed on a stage 42 in a chamber 40 of the processing apparatus. Then, for example, the gas in the two kinds of gas filling containers 43 and 44 is mixed after the flow rate is adjusted by the flow rate controllers 45 and 46, and then mixed, ejected from the ejection nozzle 47 and introduced into the chamber 40. Further, the gas in the chamber 40 is appropriately exhausted by an exhaust pump (gas exhauster) 49 through an exhaust pipe 48.
When the substance containing the fluorine-based compound of the present invention is used in a gas state, the above two types of gases are the fluorine-based compound of the present invention and nitrogen gas, or a rare gas such as argon (Ar).

  Although the resist pattern 4a is removed at the stage where the etching process of the light shielding film 3 before this process is completed, the etching process of the semi-translucent film 2 may be performed with the resist pattern 4a remaining. In this case, the surface of the light-shielding film 3 can be protected from being exposed to a non-excited fluorine-based compound substance. On the other hand, in the case of removing the resist pattern 4a, the non-excited fluorine compound substance is more uniformly supplied within the main surface, so that the pattern accuracy can be further increased.

  Next, the same resist film as described above is formed on the entire surface of the substrate after the etching process of the semi-transparent film 2 described above (if the resist pattern 4a is not removed, it is removed before forming the resist film). Draw. In the second drawing, a predetermined pattern is drawn so that a resist pattern is formed on the light shielding portion region. After the drawing, development is performed to form a resist pattern 4b on the region corresponding to the light shielding portion (see FIG. 2F).

Next, using the resist pattern 4b as a mask, the light shielding film 3 on the exposed semi-transparent portion is etched to form a pattern corresponding to the light shielding portion on the light shielding film 3. As the etching means in this case, wet etching is preferable as before. As a result, the semi-transparent film 2 on the semi-transparent part region is exposed, and a semi-transparent part is formed (see FIG. 2G). Then, the remaining resist pattern 4b is removed.
Thus, on the translucent substrate 1, the light-shielding portion 21 made of a laminated film of the semi-transparent film 2 and the light-shielding film 3, the translucent portion 22 from which the translucent substrate 1 is exposed, and the semi-transparent film 2 are formed. A three-tone mask 20 having a semi-translucent portion 23 is completed (see FIG. 2H).

According to the method for manufacturing a multi-tone mask of the present invention described above, a material containing metal and silicon, or tantalum (Ta), hafnium (Hf), zirconium (Zr), tungsten (W), zinc (Zn). , Molybdenum (Mo), titanium (Ti), vanadium (V), yttrium (Y), rhodium (Rh), niobium (Nb), lanthanum (La), palladium (Pd), iron (Fe), aluminum (Al) A semi-transparent film made of a material containing one or more metals selected from germanium (Ge) and tin (Sn) is in a non-excited state (preferably non-excited and gas state) containing the fluorine-based compound of the present invention. The etching rate for materials is high, and the glass that is the material of the light-transmitting substrate has a significantly higher etching rate for these non-excited fluorine-based compounds. Ku, high etch selectivity between the semi-transparent film made of the material is obtained. As a result, when the multi-tone mask is manufactured by etching away the semi-transparent film of the portion that becomes the translucent portion of the multi-tone mask with this non-excited fluorine-based compound substance, CD in-plane uniformity can be improved as compared with wet etching.
In particular, in the case of a semi-transparent film made of a material containing tantalum, pit-shaped concave defects generated on the substrate surface after the semi-transparent film is removed by etching can be suppressed. This makes it possible to increase the in-plane uniformity of the exposure light transmittance of the light-transmitting portion, and develop the photoresist film when the pattern is exposed and transferred to the photoresist film of the transfer object using this multi-tone mask. The amount of remaining film can be controlled with high accuracy.

In addition, since etching using a non-excited substance containing a fluorine-based compound of the present invention is applied, the chamber in which etching is performed functions sufficiently if the pressure is reduced to a certain level. For this reason, a large chamber for high vacuum such as a dry etching apparatus and a large-scale plasma generation apparatus for generating plasma over the entire main surface of the substrate are not required, and the production cost can be greatly reduced.
Furthermore, damage to the substrate after the semi-transparent film is removed by etching can be reduced. Therefore, even when the substrate is regenerated, the re-polishing process load is reduced, so that the substrate regeneration cost can be reduced. According to the present invention, since a high-quality substrate can be reproduced at low cost, it is particularly suitable for reproducing a multi-tone mask substrate using an expensive base material with high added value.
In addition, the above-described multi-tone mask manufacturing method can be easily realized by using the above-described etching apparatus of the present invention.

Next, another embodiment of the method for manufacturing a multi-tone mask of the present invention will be described.
FIG. 3 is a schematic cross-sectional view showing a multi-tone mask manufacturing process, which is a process different from that shown in FIG. The three-tone mask shown in FIG. 2 (h) and the three-tone mask shown in FIG. 3 (f) have basically the same configuration, but the manufacturing process is partially different.
2 is different from the manufacturing method of the multi-tone mask of FIG. 2 in that a resist pattern 4b having a light-shielding portion pattern is formed by the first drawing and development on the resist film 4 (see FIG. 3B). Using the resist pattern 4b as a mask, the light shielding film 3 is etched to form a light shielding portion pattern (see FIG. 3C). After the light shielding portion pattern is formed on the light shielding film 3, the light shielding film 3 is formed. A resist film is formed on the semi-transparent film 2, and a resist pattern 4a having a translucent pattern is formed by the second drawing and development (see FIG. 3D), and the resist pattern 4a The pattern of the translucent part is formed by etching the semi-transparent film 2 using as a mask (see FIG. 3E).

  In the manufacturing process of the multi-tone mask shown in FIG. 3, there is a merit that the light shielding portion can be formed only by etching the light shielding film 3 once. However, since the pattern of the translucent portion is etched and formed in the semi-transparent film 2 using the resist pattern 4a of the organic material as a mask, the light-shielding film 3 of the metal material is used as a mask as in the manufacturing process of FIG. Compared with the case where the pattern of the translucent part is formed by etching in the translucent film 2, the pattern accuracy is slightly lowered.

Hereinafter, the embodiment of the present invention will be described more specifically with reference to examples. In addition, a comparative example for the embodiment will be described.
Example 1
A sputter target is used on a translucent substrate (1220 mm × 1400 mm × 13 mm) made of synthetic quartz glass, and a mixed sintered target (Mo: Si = 20: 80) of molybdenum (Mo) and silicon (Si) as a sputter target. , Atomic% ratio) was used to form a MoSi ₄ semi-transparent film by reactive sputtering (DC sputtering) in an argon (Ar) gas atmosphere. The film thickness was 5 nm so that the transmittance was 40% at the wavelength of i-line (365 nm).

Next, a film is formed on the semi-transparent film by reactive sputtering (DC sputtering) in a mixed gas atmosphere of argon (Ar) and nitrogen (N ₂ ) using a chromium (Cr) target as a sputtering target. A CrN layer having a thickness of 15 nm is formed, and then a CrCN layer having a thickness of 65 nm is formed by reactive sputtering (DC sputtering) in a mixed gas atmosphere of argon (Ar), methane (CH ₄ ), and nitrogen (N ₂ ). Next, a CrON layer having a film thickness of 25 nm is formed by reactive sputtering (DC sputtering) in a mixed gas atmosphere of argon (Ar) and nitrogen monoxide (NO), and a total film thickness of 105 nm is formed. A chromium-based light shielding film was formed. This light shielding film is a film having a structure in which each layer has a composition gradient, and is adjusted to have an optical density of 3.0 at a wavelength of i-line (365 nm) in a laminated structure with the above-described semi-transparent film.
As described above, a mask blank was prepared in which a molybdenum silicide semi-transparent film and a chromium-based light-shielding film were laminated in this order on a translucent substrate.

Next, a three-tone mask was produced using this mask blank according to the process of FIG.
First, drawing was performed for the first time using laser light (wavelength 412 nm). A positive resist was used as the resist. A predetermined device pattern was drawn on the resist film applied on the light-shielding film, and development was performed after the drawing, thereby forming a resist pattern having a light-transmitting portion pattern (see FIG. 2B).

  Next, by using the resist pattern as a mask, the light-shielding film is wet-etched to expose the semi-transparent film corresponding to the region of the light-transmitting part, and the pattern of the light-transmitting part is formed on the light-shielding film (FIG. 2 ( c)). As an etchant, an etchant containing ceric ammonium nitrate and perchloric acid was used at room temperature. After the etching, the remaining resist pattern 4a was removed (see FIG. 2D).

Next, using the pattern of the light-transmitting portion formed on the light-shielding film as a mask, the semi-light-transmitting film on the exposed light-transmitting region is etched to form a light-transmitting portion with the substrate surface exposed (FIG. 2 ( e)).
Etching of the semi-translucent film was performed using the etching apparatus shown in FIG. That is, a substrate having a light-transmitting pattern formed on the light-shielding film is placed in the chamber, and a mixed gas of ClF ₃ and Ar (flow rate ratio ClF ₃ : Ar = 0.2: 1.8 (SLM)) is placed in the chamber. ) To replace the inside of the chamber with the gas, so that the semi-transparent film exposed on the translucent region is brought into contact with the non-excited mixed gas. At this time, the gas pressure was adjusted to 488 to 502 Torr, the temperature was adjusted to 195 to 202 ° C., and the processing time (etching time) was set to 36 seconds.

  Next, the same positive resist film as that described above was formed on the entire surface of the substrate after the above-described semi-transparent film etching step, and a second drawing was performed. In the second drawing, a predetermined pattern is drawn so that a resist pattern is formed on the light shielding portion region, and after the drawing, development is performed to form a resist pattern on the region corresponding to the light shielding portion (see FIG. 2 (f)).

Next, using the resist pattern as a mask, the light shielding film on the exposed semi-transparent part region was wet etched to form a pattern corresponding to the light shielding part on the light shielding film. In this case, the same etchant as described above was used as the etchant. Thereby, the semi-transparent film on the semi-transparent part region was exposed, and a semi-transparent part was formed (see FIG. 2G). The remaining resist pattern was removed by the same method as before.
Thus, a three-tone mask having a light-shielding portion made of a laminated film of a semi-light-transmitting film and a light-shielding film, a light-transmitting portion from which the glass substrate is exposed, and a semi-light-transmitting portion made of a semi-light-transmitting film is formed on the glass substrate. It produced (refer FIG.2 (h)).

When the surface of the glass substrate in the translucent part region where the semi-transparent film was removed by etching was observed with an electron microscope, the semi-transparent film produced was subjected to generation of residues of the semi-transparent film and altered layers such as white turbidity. Was not confirmed. The surface reflectance (200 to 700 nm) of the glass substrate in the light-transmitting region was measured, but there was no change from the substrate before film formation, and no pit-shaped concave defect was found. There was little decrease in the exposure light transmittance due to the surface roughness of the substrate, and the uniformity of the in-plane exposure light transmittance distribution was also high. It was confirmed that the CD in-plane uniformity of the semi-transparent part (semi-transparent film pattern) was also good.
In addition, when the pattern was exposed and transferred to the photoresist film of the transfer object using an ultra-high pressure mercury lamp as an exposure light source using the produced three-tone mask, the amount of the remaining film after developing the photoresist film was also highly accurate. It was confirmed that control was possible.
Further, the surface roughness of the main surface of the substrate in the light-transmitting part of the manufactured three-tone mask is determined by re-precise polishing of the substrate surface (the final stage of the normal polishing process) when the substrate of the three-tone mask is reproduced. ), The surface roughness can be easily recovered.

(Example 2)
A reactive sputtering (DC sputtering) is performed on a translucent substrate (1220 mm × 1400 mm × 13 mm) made of synthetic quartz glass, using a sputtering apparatus, using a tantalum (Ta) target as a sputtering target, and in an argon (Ar) gas atmosphere. ) To form a Ta semi-transparent film. The film thickness was 4 nm so that the transmittance was 40% at the wavelength of i-line (365 nm).

Next, a film is formed on the semi-transparent film by reactive sputtering (DC sputtering) in a mixed gas atmosphere of argon (Ar) and nitrogen (N ₂ ) using a chromium (Cr) target as a sputtering target. A CrN layer having a thickness of 15 nm is formed, and then a CrCN layer having a thickness of 65 nm is formed by reactive sputtering (DC sputtering) in a mixed gas atmosphere of argon (Ar), methane (CH ₄ ), and nitrogen (N ₂ ). Next, a CrON layer having a film thickness of 25 nm is formed by reactive sputtering (DC sputtering) in a mixed gas atmosphere of argon (Ar) and nitrogen monoxide (NO), and a total film thickness of 105 nm is formed. A chromium-based light shielding film was formed. This light shielding film is a film having a structure in which each layer has a composition gradient, and is adjusted to have an optical density of 3.0 at a wavelength of i-line (365 nm) in a laminated structure with the above-described semi-transparent film.
As described above, a mask blank was produced in which a tantalum semi-translucent film and a chromium-based light-shielding film were laminated in this order on a translucent substrate.

Next, a three-tone mask was produced using this mask blank according to the process of FIG.
First, drawing was performed for the first time using laser light (wavelength 412 nm). A positive resist was used as the resist. A predetermined device pattern was drawn on the resist film applied on the light-shielding film, and development was performed after the drawing, thereby forming a resist pattern having a light-transmitting portion pattern (see FIG. 2B).

  Next, by using the resist pattern as a mask, the light-shielding film is wet-etched to expose the semi-transparent film corresponding to the region of the light-transmitting part, and the pattern of the light-transmitting part is formed on the light-shielding film (FIG. 2 ( c)). As an etchant, an etchant containing ceric ammonium nitrate and perchloric acid was used at room temperature. After the etching, the remaining resist pattern 4a was removed (see FIG. 2D).

Next, using the pattern of the light-transmitting portion formed on the light-shielding film as a mask, the semi-light-transmitting film on the exposed light-transmitting region is etched to form a light-transmitting portion with the substrate surface exposed (FIG. 2 ( e)).
Etching of the semi-translucent film was performed using the etching apparatus shown in FIG. That is, a substrate having a light-transmitting pattern formed on the light-shielding film is placed in the chamber, and a mixed gas of ClF ₃ and Ar (flow rate ratio ClF ₃ : Ar = 0.2: 1.8 (SLM)) is placed in the chamber. ) To replace the inside of the chamber with the gas, so that the semi-transparent film exposed on the translucent region is brought into contact with the non-excited mixed gas. At this time, the gas pressure was adjusted to 488 to 502 Torr, the temperature was adjusted to 110 to 120 ° C., and the processing time (etching time) was 32 seconds.

  Next, the same positive resist film as that described above was formed on the entire surface of the substrate after the above-described semi-transparent film etching step, and a second drawing was performed. In the second drawing, a predetermined pattern is drawn so that a resist pattern is formed on the light shielding portion region, and after the drawing, development is performed to form a resist pattern on the region corresponding to the light shielding portion (see FIG. 2 (f)).

Next, using the resist pattern as a mask, the light shielding film on the exposed semi-transparent part region was wet etched to form a pattern corresponding to the light shielding part on the light shielding film. In this case, the same etchant as described above was used as the etchant. Thereby, the semi-transparent film on the semi-transparent part region was exposed, and a semi-transparent part was formed (see FIG. 2G). The remaining resist pattern was removed by the same method as before.
Thus, a three-tone mask having a light-shielding portion made of a laminated film of a semi-light-transmitting film and a light-shielding film, a light-transmitting portion from which the glass substrate is exposed, and a semi-light-transmitting portion made of a semi-light-transmitting film is formed on the glass substrate. It produced (refer FIG.2 (h)).

When the surface of the glass substrate in the translucent part region where the semi-transparent film was removed by etching was observed with an electron microscope, the semi-transparent film produced was subjected to generation of residues of the semi-transparent film and altered layers such as white turbidity. Was not confirmed. Further, the surface reflectance (200 to 700 nm) of the glass substrate in the light-transmitting region was measured, but there was no change from the substrate before film formation, and no pit-shaped concave defect was found. There was little decrease in the exposure light transmittance due to the surface roughness of the substrate, and the uniformity of the in-plane exposure light transmittance distribution was also high. It was confirmed that the CD in-plane uniformity of the semi-transparent part (semi-transparent film pattern) was also good.
In addition, when the pattern was exposed and transferred to the photoresist film of the transfer object using an ultra-high pressure mercury lamp as an exposure light source using the produced three-tone mask, the amount of the remaining film after developing the photoresist film was also highly accurate. It was confirmed that control was possible.
Further, the surface roughness of the main surface of the substrate in the light-transmitting part of the manufactured three-tone mask is determined by re-precise polishing of the substrate surface (the final stage of the normal polishing process) when the substrate of the three-tone mask is reproduced. ), The surface roughness can be easily recovered.

(Comparative Example 1)
A three-tone mask was produced using the same mask blank as in Example 2. However, in the step of etching the semi-transparent film on the exposed translucent part region using the pattern of the translucent part formed on the light-shielding film as a mask, a sodium hydroxide solution (concentration 40 wt%, temperature 70 ° C.) ) Was used as an etchant. The processing time (etching time) was 10 minutes.
The other steps were performed in the same manner as in Example 1 to produce a three-tone mask.

  When the surface of the glass substrate in the translucent region of the produced three-tone mask was observed with an electron microscope, no residue of the semi-translucent film was observed. Further, the surface reflectance (200 to 700 nm) of the substrate was measured, but the reflectance was slightly lowered as a whole as compared with the substrate before film formation. When the surface roughness of the substrate in the light transmitting portion region was observed with an atomic force microscope (AFM), it was confirmed that many pit-shaped concave portions were formed on the substrate surface of the light transmitting portion. It was confirmed that the CD in-plane uniformity of the semi-translucent portion (semi-transparent film pattern) was lower than that of Example 2.

Further, when the pattern was exposed and transferred to the photoresist film of the transfer object using an ultra-high pressure mercury lamp as an exposure light source using the produced three-tone mask, particularly in a portion where a pit-shaped recess was formed. It was a result that it was difficult to say that the amount of exposure light transmitted was greatly reduced and the amount of remaining film after development of the photoresist film could be controlled.
In addition, the surface roughness of the main surface of the substrate in the light transmitting portion of the three-tone mask is such that when the substrate of the three-tone mask is regenerated, the pit-like recesses are removed by repolishing the substrate surface. In order to restore the roughness, it is necessary to perform re-polishing from the first stage in the normal substrate polishing process before film formation, which increases the process load of re-polishing.

  The three-tone mask produced in Example 1 and Example 2 was also produced by the manufacturing method having the process of another form shown in FIG. Although the in-CD uniformity of the semi-transparent portion is not as high as that of the gradation mask, it can be confirmed that the in-CD uniformity of the semi-transparent portion is higher than that of the three-tone mask manufactured in Comparative Example 1. It was. Also, no pit-like concave defects are found on the substrate surface of the light transmitting part, the exposure light transmittance is not decreased due to the surface roughness of the substrate, and the uniformity of the in-plane exposure light transmittance distribution is high. Was confirmed.

DESCRIPTION OF SYMBOLS 1 Translucent substrate 2 Semi-transparent film 3 Light-shielding film 4 Resist film 10 Mask blank 20 Multi-tone mask 21 Light-shielding part 22 Light-transmitting part 23 Semi-translucent part 30 Transfer object 31 Substrate 32A, 32B Film 33 Resist pattern 40 Chamber 41 Processing substrate 42 Stages 43 and 44 Gas filling containers 45 and 46 Flow rate controller 47 Ejection nozzle 48 Exhaust pipe 49 Exhaust pump

Claims (8)

In a method for manufacturing a multi-tone mask having a transfer pattern comprising a light-shielding part, a light-transmitting part, and a semi-light-transmitting part that transmits part of exposure light on a glass substrate,
A material containing metal and silicon on a glass substrate, or tantalum (Ta), hafnium (Hf), zirconium (Zr), tungsten (W), zinc (Zn), molybdenum (Mo), titanium (Ti), vanadium (V), yttrium (Y), rhodium (Rh), niobium (Nb), lanthanum (La), palladium (Pd), iron (Fe), aluminum (Al), germanium (Ge) and tin (Sn) Preparing a mask blank in which a semi-transparent film made of a material containing one or more metals and a light-shielding film made of a material containing chromium (Cr) are laminated in this order;
Forming a light-transmitting portion pattern on the light-shielding film;
Using the pattern of the light-transmitting portion formed on the light-shielding film as a mask, the semi-transparent film is made of any element of chlorine (Cl), bromine (Br), iodine (I), and xenon (Xe) Etching with a non-excited substance comprising a compound of benzene and fluorine (F);
Forming a pattern of a light-shielding portion on the light-shielding film.   2. The step of forming a light transmitting portion pattern on the light shielding film is performed by wet etching using a resist film having a light transmitting portion pattern formed on the light shielding film as a mask. Of manufacturing a multi-tone mask.   3. The step of forming a light shielding part pattern on the light shielding film is performed by wet etching using a resist film having a light shielding part pattern formed on the light shielding film as a mask. Of manufacturing a multi-tone mask. 4. The method of manufacturing a multi-tone mask according to claim 1, wherein the non-excited substance is ClF ₃ gas. 5.   5. The method for manufacturing a multi-tone mask according to claim 1, wherein the semi-translucent film is made of a material containing tantalum (Ta). 6.   The method for manufacturing a multi-tone mask according to claim 1, wherein the metal in the semi-transparent film is molybdenum (Mo).   The method for manufacturing a multi-tone mask according to claim 1, wherein the light shielding film is made of a material further containing nitrogen.   The method for manufacturing a multi-tone mask according to any one of claims 1 to 7, wherein the glass substrate is made of synthetic quartz glass.

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