JP2001337437A - Producing method of blanks for photomask and method for producing photomask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film which has high uniformity of optical characteristic in the surface of substrate. SOLUTION: This method for producing blanks for photomask is provided with a target and a substrate which is disposed on the position opposed to the target and is the object to be film-formed in a chamber and enables the reactive sputtering by supplying sputtering gases including a reactive gas into the chamber. This method for producing blanks for photomask is further characterized by that a target which is perforated with gas emitting holes communicated with a gas supplying pipe is used as the target and the reactive sputtering is performed while supplying the sputtering gas including the reactive gas toward the substrate through the gas emitting holes of the target.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a photomask blank used for photolithography and a method for manufacturing a photomask.
I. VLSI and other high-density semiconductor integrated circuits, CCDs (Charge Coupled Devices), color filters for LCDs (Liquid Crystal Display Devices), manufacturing methods of photomask blanks suitably used for fine processing of magnetic heads, etc. And a method for producing the same.

[0002]

2. Description of the Related Art
High density semiconductor integrated circuits such as LSI and VLSI, CCD
Photolithography technology using a photomask is used for fine processing of (charge-coupled devices), color filters for LCDs (liquid crystal display devices), and magnetic heads.

[0003] As the photomask, quartz glass,
A chromium-based light-shielding film is usually formed on a transparent substrate such as aluminosilicate glass by a sputtering method or a vacuum evaporation method, and a light-shielding film of a photomask blank having a predetermined pattern is used.

Such a photomask is used for a photomask blank in which a chromium-based light-shielding film is formed on a substrate.
After applying a photoresist or an electron beam resist, a predetermined pattern is selectively exposed to light, and a resist pattern is formed through a developing step, a rinsing step, and a drying step. Then, using the resist pattern as a mask, wet etching is performed using an etching solution composed of a mixed aqueous solution of cerium ammonium nitrate and perchloric acid, or a portion not masked by performing dry etching using a chlorine-based gas. By removing the chromium-based film and then removing the resist, a photomask having a predetermined pattern including a light-shielding portion and a light-transmitting portion can be formed.

In this case, the chromium-based light-shielding film has a high light reflectance, and prevents light reflected on the semiconductor substrate as an object to be exposed from being reflected by the photomask through the projection lens and returning to the semiconductor substrate again. Therefore, an antireflection film is usually formed on the front surface, the front surface, and the back surface of the light-shielding film.

As a photomask having the antireflection film and a blank for the photomask, a chromium carbonitride film containing chromium carbide and chromium nitride as an antireflection film and a chromium film as a light shielding film are formed on a transparent substrate. There has been proposed a photomask blank in which chromium carbide and a chromium carbonitride film containing chromium nitride are sequentially laminated (Japanese Patent Publication No. 62-37385). Further, a film using CrON as an antireflection film (Japanese Patent Publication No. 61-46)
No. 821, Japanese Patent Publication No. 62-32782), an antireflection film using CrN (Japanese Patent Publication No. 62-273).
No. 86, Japanese Patent Publication No. 62-27387) and the like. Further, a light-shielding film using Cr (Japanese Patent Publication No. 61-46821) and a light-shielding film using Cr
A device using C (Japanese Patent Publication No. 62-27387) has been proposed.

Further, photomask blanks in which a chromium-based film is formed on a half-tone film to increase the resolution have also been put to practical use.

Further, a method of processing into a fine shape using light interference called a phase shift film for performing fine processing has been performed, and a chromium film or a molybdenum silicide film to which oxygen is added is subjected to a phase shift. A film used alone as a shift film (Japanese Patent Application Laid-Open No. 4-136854), a film used in combination with a light-shielding film and a phase shift film (Japanese Patent Publication No. 62-59)
296) has been proposed. In addition, Cr or C containing at least one of oxygen, nitrogen, and carbon
A method using r as a film material (Japanese Patent Application Laid-Open No. 62-18560) and a method of forming a reactive sputter film using oxygen and CH ₄ as reactive gases (Japanese Patent Application Laid-Open No. 7-43888) have been proposed. I have.

In recent years, as the integration and speed of LSIs have increased, the pattern rules have been required to be finer, and the photomasks used for forming the patterns have also been required to be finer. As one of the solutions, it has been studied to make the film quality uniform. In particular, phase shift films have variations in film quality, and when the optical constants change, the transmittance and phase change, and the effect of interference with a place without a phase shift film differs in the plane, resulting in a change in pattern processing accuracy. What has been desired is a film having higher film quality uniformity.

In this case, Cr oxide used for the anti-reflection film and MoSiON used for the phase shift film are generally formed by a reactive sputtering method. With this reactive sputtering method, the target material is not sputtered as it is to form a film,
This is a method of forming a film of an oxide, a nitride, or the like of a target material by flowing a reactive gas that forms a compound such as oxygen or nitrogen into a process chamber during film formation.

In the above reactive sputtering, as a method for introducing a sputtering gas containing a reactive gas into the chamber, a gas supply port 10 is provided on the side wall of the chamber 3 as shown in FIG. Generally, reactive sputtering is performed by flowing a sputter gas containing a reactive gas into the chamber 3 through the port 10 to form a film.

However, in the above method of supplying a sputtering gas, the gas concentration varies in the chamber, and the reactive gas is mainly consumed at the outer edge (gas supply port side) in the target surface. The reactive gas is not sufficiently distributed from the central portion to the outer edge portion on the opposite side of the gas supply port, and the concentration distribution of the reactive gas on the target surface is biased. There is a problem that film quality uniformity is impaired.

The present invention has been made in view of the above circumstances, and is capable of supplying a reactive gas with a uniform concentration distribution on a target surface, improving the in-plane distribution of film quality of a film to be formed, and improving the substrate quality. An object of the present invention is to provide a method for manufacturing a photomask blank and a method for manufacturing a photomask, which can obtain a film having high uniformity of in-plane optical characteristics.

[0014]

Means for Solving the Problems and Embodiments of the Invention In order to achieve the above object, the present inventors have made intensive studies on a method of supplying a sputtering gas containing a reactive gas in a reactive sputtering method, and as a result, By using a target having a gas emission hole communicating with the reactive gas supply pipe and performing reactive sputtering while supplying a sputtering gas containing a reactive gas toward the substrate through the gas emission hole of the target, the target It has been found that the concentration distribution of the reactive gas on the surface is greatly improved, and a film having extremely high film quality uniformity such as optical characteristics in the substrate surface can be formed.

That is, the present invention provides the following method for manufacturing a photomask blank and a method for manufacturing a photomask. Claim 1: Reactive sputtering by providing a target and a substrate to be formed and disposed at a position facing the target in a chamber, and supplying a sputtering gas containing a reactive gas into the chamber. In the method of manufacturing a photomask blank by performing the above, while using a target provided with a gas discharge hole communicating with the gas supply pipe as the target, the reactive gas toward the substrate through the gas discharge hole of the target A method for producing a blank for a photomask, wherein reactive sputtering is performed while supplying a sputtering gas containing the same. Claim 2: A gas emission hole is formed in the target,
2. The method for producing a photomask blank according to claim 1, wherein a gas introduction pipe having gas emission holes is provided around the target, and a sputtering gas containing a reactive gas is supplied toward the substrate through the gas emission holes. . Claim 3: MoSi based material or C as target material
3. The method for producing a photomask blank according to claim 1, wherein an r-based material is used. In a fourth aspect of the present invention, there is provided a method of manufacturing a photomask, comprising: forming a photomask blank obtained by the method according to any one of the first to third aspects by lithography.

According to the present invention, a target and a substrate to be formed and disposed at a position facing the target are provided in a chamber, and a sputtering gas containing a reactive gas is supplied into the chamber. When manufacturing a photomask blank by performing reactive sputtering, a target having a gas discharge hole communicating with a gas supply pipe is used, and a reactive gas is discharged toward the substrate through the gas discharge hole of the target. By performing the reactive sputtering while supplying the sputtering gas containing the gas, the outer peripheral portion (the gas supply port side) in the target surface is formed like the conventional method of supplying the sputtering gas containing the reactive gas from the side wall of the chamber. Because the reactive gas is mainly consumed,
The problem that the sputtering gas does not sufficiently spread from the center of the substrate to the outer edge opposite to the gas supply port is eliminated, the concentration distribution of the reactive gas on the target surface becomes uniform, and optical It is possible to form a film in which film quality uniformity such as characteristics is dramatically improved.

Further, according to the manufacturing method of the present invention, it is possible to supply a reactive gas with a uniform concentration distribution on the target surface, and the in-plane distribution of the film quality of the film to be formed is greatly increased. It is possible to obtain photomask blanks and photomasks that are optimal for anti-reflection films and phase shift films that require high in-plane uniformity of film quality, enabling more accurate pattern processing, and further semiconductor integrated circuits. It can respond to high integration and miniaturization of the device.

Hereinafter, the present invention will be described in more detail. The method for producing a photomask blank of the present invention includes:
As shown in FIG. 1, a target 1 and a substrate 2 which is a film formation target disposed at a position facing the target 1 are provided in a chamber 3, and a sputtering gas containing a reactive gas is provided in the chamber 3. When supplying a gas and performing reactive sputtering, a target 1 having a gas discharge hole 4 communicating with a gas supply pipe 5 is used as the target, and the substrate 2 is passed through the gas discharge hole 4 of the target 1. It is characterized in that reactive sputtering is performed while supplying a sputtering gas containing a reactive gas toward the surface, whereby the concentration distribution of the reactive gas on the target surface becomes uniform and the film quality uniformity is improved. . In addition, 7 in FIG. 1 shows a backing plate.

Here, as the target, targets having various shapes such as a disk shape, a square plate shape, a rectangular plate shape, and a cylindrical shape can be used, but a disk-shaped target is particularly preferable. The diameter of the disk target is usually about 50 mm to 400 mm, and the thickness is 3 mm to 20 mm.
It is about.

The target material is selected according to the composition of the target thin film, but it is particularly preferable to use a MoSi-based material or a Cr-based material. For example, when a MoSi-based film is formed, it is preferable to use MoSi or a target in which oxygen, nitrogen, carbon, or the like is added to MoSi. When forming a Cr-based film, Cr or Cr
It is preferable to use a target to which oxygen, nitrogen, carbon, or the like is added.

The method of manufacturing the target differs depending on the target material. For example, a pure metal target is obtained by rolling at room temperature and cutting it into a required shape. However,
High melting point materials such as Hf, Re, W, and Mo can be obtained by rolling at a high temperature. In addition to these, casting molding, a method of molding metal powder, and the like can also be employed. In the case of an alloy (composite) target, the target can be formed by a method in which the alloy is vacuum-melted and rolled, or a method in which the target surface is made of each component metal of the alloy and the composite target is sputtered. In the case of a non-metallic target, it can be formed by hot pressing, slip casting, isostatic pressing, or a usual sintering method.

As the target used in the manufacturing method of the present invention, as shown in FIG. 2, a target 1 having a gas discharge hole 4 communicating with a gas supply pipe (not shown) is used. In this case, the number of gas emission holes drilled in the target,
The size of the gas emission holes and the arrangement of the gas emission holes in the substrate surface are not particularly limited as long as the sputtering gas containing the reactive gas can be uniformly supplied to the substrate provided at the opposed position without bias. For example, in the case of a circular target having a diameter of 200 mm, 1 to 300 gas discharge holes having a diameter of 0.5 mm to 10 mm are uniformly arranged (for example, radially arranged or arranged on a similar circle) in the substrate surface. Is preferred.

Further, as shown in FIG.
A gas introduction hole 6 having a gas emission hole 4 is provided around the target 1.
It is preferable to supply a sputtering gas containing a reactive gas toward the substrate 1 through the gas discharge holes 4 of the target and the gas introduction pipe from the viewpoint of further improving the film quality uniformity. In this case, the gas introduction pipe may be provided with one or more gas discharge holes, more preferably about 1 to 20 gas discharge holes. In addition, it is preferable to provide the gas discharge holes of the gas introduction pipe evenly.

By appropriately adjusting the size, number, and arrangement of the gas emission holes provided in the target, the concentration distribution of the reactive gas on the target surface can be finely adjusted, and the optical distribution in the substrate surface can be finely adjusted. The uniformity of film quality such as characteristics can be improved, and a concentration gradient of a desired composition can be provided.

As a method of forming a gas discharge hole in the target, the target obtained as described above was drilled in the depth direction with a drill, and a groove was previously formed so as to be a passage through which gas flows. On the backing plate, the target and the backing plate are bonded together so that the target hole is on the groove of the backing plate, and the end of the groove of the backing plate is used as a gas inlet or a passage through which gas flows in advance. Cut the groove, glue the target to the processed backing plate so that the end of this groove becomes the gas inlet, and form a hole in the target just above the groove of the backing plate, etc. Can be.

As the sputtering gas, Ar, Ne, Kr
A sputtering gas in which a reactive gas is added to an inert gas such as the above in accordance with a desired film composition is preferably used. In this case, as the reactive gas, a gas containing carbon such as CH ₄ , CO ₂ , CO, a gas containing nitrogen such as NO, NO ₂ , N ₂ , a gas containing C,
Gases containing oxygen such as O ₂ , NO, and O ₂ are mentioned.

According to the production method of the present invention, reactive sputtering is performed by supplying a sputtering gas obtained by mixing an inert gas such as argon and krypton and a reactive gas such as oxygen, nitrogen and carbon dioxide from a gas discharge hole of a target. In particular, it is preferable to supply the sputtering gas from the gas discharge holes of the target and the gas discharge holes provided in the ring-shaped gas introduction pipe around the target. The method of supplying the sputtering gas is not limited to these, and the sputtering gas may be supplied simultaneously from the gas discharge hole of the target and the gas supply port provided on the side wall of the chamber.
In this case, only reactive gases such as oxygen, nitrogen, carbon dioxide, etc. are introduced from the gas discharge holes of the target, and Ar, Ne, K
It is preferable to introduce an inert gas such as r from a gas supply port on the side wall of the chamber.

The supply of the sputtering gas to the gas discharge holes of the target is not particularly limited. For example, a groove communicating with the gas supply pipe is formed on the target support and the groove is communicated with the gas discharge holes. And so on.

The substrate used for film formation is, for example, transparent quartz,
Aluminosilicate glass, calcium fluoride, magnesium fluoride, or the like can be used.

As the reactive sputtering method, direct current (DC)
A power source or a radio frequency (RF) power source may be used, and a magnetron sputtering method or a conventional method may be used.
Sputtering is preferred because the mechanism is simple. Also,
The use of a magnetron is preferred in that the film formation rate is increased and productivity is improved. Note that the film forming apparatus may be a passing type or a single wafer type.

The blank for photomasks obtained by the manufacturing method of the present invention has the above structure, whereby the concentration distribution of the reactive gas on the target surface becomes uniform, and the in-plane distribution of the film quality becomes uniform. Is preferably 0.1 or less, more preferably 0.1 or less.
05 or less, and has more uniform optical characteristics than the conventional method using a sputtering apparatus as shown in FIG. (Max-min) / (max + min) = D [where, max represents the maximum value of the reflectance measurement value, and min represents the minimum value of the reflectance measurement value. ]

For example, using a sputtering apparatus as shown in FIG. 1, MoSi having a large number of gas emission holes as shown in FIG. 2 as a target, and a mixture of Ar, oxygen and nitrogen as a sputtering gas. A MoSiON film is formed by reactive sputtering using a gas.
When the reflectivity of the oSiON film at a wavelength of 400 to 450 nm is measured at an interval of 5 mm using an in-plane distribution of reflectivity using Nanometrics manufactured by Nanometrics, the reflectivity in the substrate surface is represented by the above equation. The variation D is 0.1 or less, more preferably 0.05 or less.

The film structure of the photomask blank of the present invention may be not only a two-layer film or a three-layer film but also a four-layer film. Further, a combination with a phase shift film for changing the phase of the exposure wavelength may be used. Also,
The present invention can be applied not only to a transmission type but also to a reflection type mask.

In the case of manufacturing a photomask using the photomask blank of the present invention, as shown in FIG. 4A, after forming the thin film layer 12 on the substrate 11 as described above, A resist film 13 is formed on the thin film layer 12, the resist film 13 is patterned as shown in FIG. 4B, and further, as shown in FIG.
2 after dry or wet etching,
As shown in FIG. 4D, a method of removing the resist film 13 or the like can be employed. In this case, application of a resist film,
Patterning (exposure and development), dry etching or wet etching, and removal of the resist film can be performed by known methods.

The photomask obtained by the manufacturing method of the present invention has high uniformity of film quality such as in-plane optical characteristics.
A pattern having a desired fine width can be accurately formed, and it is possible to sufficiently cope with further high integration and miniaturization in a semiconductor integrated circuit device or the like.

[0036]

EXAMPLES The present invention will be described below in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Example 1] On a 6 "quartz substrate, 8" MoSi _2.3 was used as a target (21 gas discharge holes having a diameter of 3 mm and arranged in the arrangement shown in FIG. 2). Using the sputtering apparatus shown in FIG.
And a gas pressure of 0.3 Pa, 500 W during discharge by flowing a sputtering gas in which oxygen and nitrogen are mixed in a volume ratio of 7: 4: 4.
A MoSiON film was formed by a DC sputtering method at a film formation temperature of 120 ° C.

With respect to the obtained MoSiON film, 450
The reflectivity at the wavelength of nm was measured using Nanospec manufactured by Nanometrics Co., Ltd., and the in-plane distribution of the reflectivity was measured at intervals of 5 mm. The variation D represented by the following equation was 0.038. (Max-min) / (max + min) = D [where, max represents the maximum value of the reflectance measurement value, and min represents the minimum value of the reflectance measurement value. ]

[Comparative Example 1] On a 6 "quartz substrate, 8" MoSi _2.3 was used as a target (without gas release holes).
A sputtering gas in which Ar, oxygen, and nitrogen are mixed at a volume ratio of 7: 4: 4 flows from the gas supply port 10 on the side wall of the chamber of the sputtering apparatus shown in FIG. 5, and the gas pressure during discharge is 0.3 Pa and 500 W. The MoSiON film was formed at a film forming temperature of 120 ° C. by a DC sputtering method.

With respect to the obtained MoSiON film, 450
The reflectivity at a wavelength of nm was measured using a Nanospec manufactured by Nanometrics Co., Ltd., and the distribution of the reflectivity in the plane of the substrate was measured at intervals of 5 mm. Variation D represented by the following equation was 0.24. (Max-min) / (max + min) = D [where, max represents the maximum value of the reflectance measurement value, and min represents the minimum value of the reflectance measurement value. ]

[0041]

According to the present invention, reactive sputtering is performed by using a target having a gas discharge hole and supplying a sputtering gas containing a reactive gas toward the substrate through the gas discharge hole of the target. Thus, unlike the conventional method of supplying a sputtering gas containing a reactive gas from the side wall of the chamber, the reactive gas is mainly consumed at the outer edge portion (gas supply port side) in the target surface, so that the center of the substrate is The problem that the sputtering gas does not sufficiently spread to the outer edge portion opposite to the gas supply port is resolved, the concentration distribution of the reactive gas on the target surface becomes uniform, and the film quality uniformity such as optical characteristics is high. A film can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic view of a sputtering apparatus according to one embodiment of the present invention.

FIG. 2 is a plan view of a target of the present invention.

FIG. 3 is a plan view of another target.

FIG. 4 is an explanatory view showing a method for manufacturing a photomask,
(A) is a state in which a resist film is formed, (B) is a state in which the resist film is patterned, (C) is a state in which dry etching or wet etching is performed, and (D) is a schematic cross-sectional view in a state in which the resist film is removed. It is.

FIG. 5 is a schematic view of a conventional sputtering apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Target 2 11 Substrate 3 Chamber 4 Gas discharge hole 5 Gas supply pipe 6 Gas introduction pipe 7 Backing plate 10 Gas supply port

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Satoshi Okazaki 28-1 Nishifukushima, Kazagi-son, Nakakubijo-gun, Niigata Prefecture F-term (reference) 2H095 BC05 BC08

Claims (4)

[Claims] A chamber includes a target and a substrate to be formed, which is disposed at a position facing the target, and a sputtering gas containing a reactive gas is supplied into the chamber to generate a reactive gas. In the method for manufacturing a photomask blank by performing sputtering, a target having a gas discharge hole communicated with a gas supply pipe is used as the target, and a reactive gas is directed toward the substrate through the gas discharge hole of the target. And performing reactive sputtering while supplying a sputtering gas containing the same. 2. A gas discharge hole is formed in a target, and a gas introduction pipe having a gas discharge hole is provided around the target. A sputtering gas containing a reactive gas is directed toward the substrate through the gas discharge hole. The method for producing a photomask blank according to claim 1, wherein a gas is supplied. 3. The method according to claim 1, wherein a MoSi-based material or a Cr-based material is used as the target material. 4. A method for manufacturing a photomask, comprising: patterning a photomask blank obtained by the method according to claim 1 by a lithography method.