JPH06130649A - Phase shift mask and production of blanks for phase shift mask - Google Patents

Abstract

PURPOSE:To improve adhesion to a base substrate and to reduce the number of defect generation in masks by cleaning the base substrate surface by a gas plasma which leaves no SOG (spin on glass) and no reactive residues, etc., on the base substrate. CONSTITUTION:The base substrate 1 is constituted by providing with a conductive layer 3 consisting of SnO2, etc., on a transparent substrate 2 and is subjected to a surface cleaning treatment 4 by Ar plasma and is then coated and formed with SOG shifter layer 5 with a spinner. Then, Cr light shielding film 7 is formed by a sputtering method 6 to form a blanks 8 for phase shift mask in which the substrate 1, the SOG film and the light shielding film 7 are arranged. By applying the plasma treatment in such a manner, stickings of residues or products to the base substrate surface which are peculiar to a water cleaning treatment are eliminated and the base substrate surface and the SOG film are not deteriorated. By applying the cleaning treatment with the Ar gas plasma to the base substrate surface, the base substrate surface is activated and the adhesion between the base substrate 1 and the SOG film is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase shift mask and blanks for the phase shift mask, and more particularly to S
The present invention relates to the adhesion between the SOG and the underlying substrate when OG (spin on glass) is used.

[0002]

2. Description of the Related Art Conventionally, as a method of cleaning a photomask substrate, acid cleaning using chemicals, physical ultrasonic cleaning, scrub cleaning, etc. have been used. When SOG was applied to a base substrate using a phase shift mask or a phase shift mask blank using spin-on-glass, adhesion between SOG and the base substrate was not sufficient. It is said that all of the above-mentioned cleaning methods use water, and therefore residues remain on the surface of the underlying substrate after cleaning, although they are minute. As another method for cleaning the surface of the substrate, there is also known a plasma treatment using ozone or oxygen, which is used for cleaning the base substrate surface of a phase shift mask or phase shift mask blanks using SOG as a shifter layer. Even when it was present, the adhesion between the SOG and the base substrate was not sufficient. It is said that the cause of this is that an atmosphere of ozone or oxygen remains on the substrate surface, albeit slightly.
Here, SOG (spin on glass) will be briefly described. SOG is prepared by diluting an organic silicon compound with an organic solvent to a volume ratio of about 10 times, coating it on a base substrate, and drying it.
It is heated to change it to silicon oxide. Here,
It is used as a phase shift layer after plate-making.
As a starting material for SOG, tetraethoxysilane (S
A metal alkoxide such as i (OCH ₂ H ₅ ) ₄ ), an amphoteric solvent such as water and methanol, and hydrochloric acid are used. Also, S
In order to leave a methyl group (—CH ₃ ) in OG, triethoxymethylsilane (CH ₃ Si (OCH ₂ H ₅ ) ₃ ) is used.
And diethoxydimethylsilane ((CH ₃ ) ₂ Si (OC
₂ H ₅ ) ₂ ) is also added to the tetraethoxysilane in an amount of several% to several tens%. It is said that the adhesion of the SOG to the base substrate is affected by the residual moisture and humidity on the base substrate and the amount of the residual solvent in the SOG, and it is generally difficult to secure stable adhesion to the base substrate. It is said that. Even if a conventional substrate cleaning method is used for the production of such a phase shift mask using SOG as a phase shifter layer, which is different from the conventional photomask, sufficient adhesion between the SOG and the underlying substrate can be obtained. Since this is not possible, a cleaning method that suits the unique mask structure and material has become necessary. There is also known a method of coating HMDS (hexamethyldisilazalin) on the base substrate to improve the adhesion between the SOG and the base substrate, but in this case, the usable SOG material is limited. There was a problem that became.

[0003]

As described above, the SOG
In a phase shift mask or a phase shift mask blank having a shifter layer as a
There is no method for cleaning the surface of the substrate to ensure sufficient adhesion between the G and the substrate, and the adhesion between the SOG and the underlying substrate is the same as the light-shielding film (chrome etc.) in the conventional photomask and the underlying substrate (QZ transparent substrate). (Structure in which a conductive layer such as SnO ₂ is provided) is significantly inferior to that in the manufacturing process of the phase shift mask or the phase shift mask blanks, and the SOG film before or after heating is separated from the underlying substrate, It was a problem. As a result, the manufacturing yield of the phase shift mask is reduced, the manufacturing period is lengthened, and the cost is increased, which is a serious problem, and a method for cleaning the substrate that can improve the adhesion between the SOG and the substrate is required. Became.

[0004]

The present invention thus provides:
SOG in phase shift masks, phase shift masks and phase shift mask blanks using SOG as a shifter layer
In order to improve the adhesion between the substrate and the underlying substrate, unlike the above-mentioned conventional substrate cleaning method, like the water-based cleaning method, residue or product may be left on the substrate surface after cleaning, S in plasma processing using ozone and oxygen
A method in which the residue or product reactive with OG does not reach the surface of the substrate and the surface of the underlying substrate is cleaned to a molecular level and the surface of the underlying substrate is activated to improve the adhesion between the SOG and the underlying substrate. Is provided.

According to the present invention, at least the surface of the underlying substrate is cleaned with a gas plasma that does not deteriorate the underlying substrate and does not leave residues or products reactive with SOG on the underlying substrate. SOG film to be a shifter is applied.
The surface of the base substrate before G coating is processed. In the case of Ar plasma, the base substrate is altered or S
It is an inert gas plasma that does not leave residues or products that are reactive with OG, and does not leave residues that are reactive with SOG on the surface of the underlying substrate as in plasma processing using ozone or oxygen. The surface can be cleaned at the molecular level and the underlying substrate can be activated. As described above, the present invention has a problem of a residue or a product after cleaning in a conventional water-based cleaning method, and a residue or a product reactive with SOG in a cleaning treatment with ozone or oxygen plasma. The problem is solved, the surface of the base substrate is cleaned to a molecular level, and the surface of the base substrate is activated to improve the adhesion between the SOG and the base substrate. Here, since the reason for Ar plasma treatment is as described above, it is needless to say that the same action and effect can be applied to plasma of an inert substrate such as Xe instead of Ar. In addition, the gas plasma is not limited to Ar or Xe as long as it has the same action and effect. The gas plasma treatment of the present invention basically does not change the quality of the underlying substrate and applies S on the underlying substrate.
A substrate cleaning treatment that does not leave a residue or a product reactive with the OG film has a cleaning effect on the surface of the underlying substrate. Furthermore, the surface of the underlying substrate can be cleaned up to the molecular level. It is characterized by activating the base substrate surface by plasma such as Ar in a dry process which is not a water-based process, that is, the base substrate surface is activated by plasma by an ion bomber effect. is there.

[0006]

With the above arrangement, the present invention has the following actions. (1) By adopting the plasma treatment, it is possible to prevent the residue or the product from adhering to the underlying substrate surface, which is peculiar to the water-based cleaning treatment, and when the SOG film is applied, the underlying substrate surface and the SOG film are not altered. . (2) By cleaning the surface of the underlying substrate with a gas plasma such as Ar gas plasma, the underlying substrate is not deteriorated and no residue or product reactive with SOG is deposited on the surface of the underlying substrate. (3) By cleaning the base substrate surface with a gas plasma such as Ar gas plasma, the base substrate can be cleaned up to the molecular level, the base substrate surface can be activated, and the base substrate and SOG film can be activated. Improves adhesion.

[0007]

EXAMPLES Examples will be described below with reference to the drawings. Figure 1
FIG. 2 is a diagram for explaining a method of manufacturing a blank for a phase shift mask in which a base substrate, an SOG film, and a light shielding film of the present invention are arranged in this order. 2 is a transparent substrate, 3 is a conductive layer, and 1 is a transparent substrate 2. And a base substrate formed of the conductive layer 3, 4 is a surface treatment for cleaning the base substrate with Ar plasma, 5 is an SOG shifter layer,
Reference numeral 6 indicates a sputtering process, and 7 indicates a light shielding film of Cr. First, as shown in FIG. 1A, a base substrate 1 having a conductive layer 3 made of SnO ₂ on a transparent substrate 2 made of QZ is formed as shown in FIG.
Ar plasma surface cleaning treatment 4 is performed as shown in (b),
Thereafter, as shown in FIG. 1C, the SOG shifter layer 5 is applied and formed by a spinner, and then a Cr light shielding film 7 is formed by a sputtering method 6 as shown in FIG.
A blank 8 for a phase shift mask in which an SOG film and a light shielding film were arranged in this order was prepared. Then, using this blank, a phase shift mask was prepared as shown in FIG. The steps will be described with reference to the drawings. Phase shift mask blank ^8, of ionizing radiation resist 9 positive type coated on the Cr light blocking layer (a), EB lithography apparatus with an electron beam 10 at (electronic Pimu drawing apparatus) drawn in accordance with a desired pattern ( b), a resist pattern 11 is formed (c), and then
Chlorinated methane + using resist pattern 11 as a protective film
After the Cr light-shielding film was etched using oxygen gas 12 (d), the resist was removed using oxygen gas 13 (e) to form a Cr light-shielding film pattern 14 (f). Next, a negative type ionizing radiation resist 15 is applied on the Cr light-shielding film pattern 14 (g), an electron beam is drawn by an EB drawing machine according to a desired pattern shape (h), and the resist 15 is developed. After forming the resist pattern 16 (i), the resist pattern 16 and the Cr light shielding layer pattern 14 are formed.
As protective film, SOG shifter layer ^5, the etching using a gas 17 of tetrafluoromethane + oxygen, to form an SOG shifter pattern 18 (j). Then, oxygen gas 13 ^,
Using (k), the resist was removed to produce a phase shift photomask 19 (m). The defects of the phase shift mask thus obtained were extremely small and the number thereof was small as compared with those of the conventional treatment. still,
Although the above-described etching of the Cr layer and the shifter layer is a dry etching method, wet etching may be used.

[0008]

INDUSTRIAL APPLICABILITY As described above, the SOG (spin-on-glass) of the present invention is used as the shifter layer, the base substrate and the SOG
In the method of manufacturing a phase shift mask or a blank for a phase shift mask, in which a film and a light shielding film are arranged in this order,
It is possible to improve the adhesiveness between the underlying substrate and the SOG, and thereby reduce the number of defects generated in the mask, which in turn can stabilize the quality, and achieve a stable phase shift mask and phase shift. It became possible to provide blanks for masks.

[Brief description of drawings]

FIG. 1 is a diagram of a blank for a phase shift mask of the present invention.

FIG. 2 is an explanatory diagram of a phase shift mask.

[Explanation of symbols]

1 ^, 1 ^, base substrate 2 ^, 2 ^, Qz transparent substrate 3 ^, 3 ^, SnO ₂ conductive layer 4 Ar plasma base substrate surface cleaning treatment 5 ^, 5 ^, SOG shifter layer 6 sputtering treatment 7 Cr light-shielding film 8 ^, 8 ^, phase Blanks for shift mask 9 Positive type ionizing radiation resist 10 ^, 10 Electron beam 11 Resist pattern 12 Chlorinated methane + oxygen gas 13 ^, 13 ^, Oxygen gas 14 Cr light-shielding film pattern 15 Negative ionizing radiation resist 16 Resist pattern 17 Fluoride Methane + oxygen gas 18 SOG shifter pattern 19 Phase shift photomask

Claims (3)

[Claims] 1. In a phase shift mask manufacturing process in which an SOG (spin on glass) is used as a shifter layer and an underlying substrate, an SOG film, and a light-shielding film are arranged in this order, at least the underlying substrate is not altered, The base substrate surface is cleaned with an inert gas plasma that does not leave residues or products reactive with SOG on the base substrate, and then SOG is performed.
Method for manufacturing phase shift mask characterized in that film is applied 2. In a manufacturing process of a phase shift mask blank comprising an SOG (spin-on-glass) shifter layer, an underlying substrate, an SOG film, and a light-shielding film, which are arranged in this order, at least the underlying substrate is altered. Without cleaning, the surface of the base substrate is cleaned with an inert gas plasma that does not leave residues or products reactive with SOG on the base substrate.
Next, a method for manufacturing a blank for a phase shift mask, characterized by applying an SOG film 3. A method for manufacturing a phase shift mask or a blank for a phase shift mask, wherein the inert gas plasma according to claim 1 or 2 is gas plasma of an inert gas such as Ar or Xe.