JPH101330A - Glass having satisfactory transmittance in ultraviolet region - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve UV transmittance in a short wavelength region by incorporating NH4 F.HF. SOLUTION: A mixture consisting of, by mol, 0.2-25%P2 O5 , 0-10% Al2 O3 , 0-40% AlF3 , 0-15% MgF2 , 0-30% CaF2 , 0-30% SrF2 , 0-25% BaF2 , 0-5% ZnF2 , 0-15% YF3 , 0-5% LiF, 0-5% NaF, 0-5% KF, 0.01-1% NH4 F.HF, 0-2% SiF4 , 0-5% PF5 , 0-5% MgO, 0-5% CaO, 0-5% SrO, 0-5% BaO, 0-5% ZnO, 0-15% Y2 O3 , 0-2% Li2 O, 0-2% Na2 O and 0-2% K2 O and regulating the atomic ratio of O to F to 0.01-2 is melted by heating at 850-1,150 deg.C for 1-5hr, stirred, refined, homogenized and cooled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical glass exhibiting excellent transmittance in a short wavelength region, particularly in an ultraviolet ray of about 350 nm or less.

[0002]

2. Description of the Related Art In recent years, the integration of semiconductor devices such as LSIs has been remarkably advanced, and in the manufacture thereof, the miniaturization of devices has been rapidly progressing. It is the photolithography technology that enables the miniaturization of the element in this manner, and the wavelength of light used in these semiconductor exposure apparatuses shifts from the g-line (405 nm) to the i-line (365 nm) to a shorter wavelength side. I've been. Recently, a KrF excimer laser having a shorter wavelength has been used. For i-line glass, see the i-line glass catalog (199
(Issued for one year), high transmittance is provided by glasses of various compositions according to detailed purposes, and these are utilized. However, KrF excimer lasers hardly transmit even these glasses, and although there are some which have very good transmittance only for synthetic quartz and alkali or alkaline earth halide crystals, halide Are not very good in homogeneity. Therefore, the optical system is made of only quartz, but this also has a problem of aberration.

[0003] Conventionally, fluorophosphate glass is known as a glass having a relatively good ultraviolet transmittance, but it is difficult to impart sufficient transmittance to light having a wavelength of 300 nm or less. Met. Currently, as the permeability good fluoride phosphate glass KrF excimer laser light, is contained BaCl ₂ from 0.5 to 16.5 mol%, for example, small amounts phosphate-containing fluoride glass of JP-A 2-283635 JP Only those which introduce OH ions into phosphate glass described in JP-A-8-104538 are known. However, the glass described in JP-A-2-283635 introduces a large amount of chloride ions for improving the stability, and therefore, sufficient transmittance cannot be obtained in an ultraviolet region of 350 nm or less. Also, JP-A-8-104
The glass described in Japanese Patent No. 538 introduces OH ions in the form of water vapor or hydroxide. However, when water vapor is introduced, chemical durability tends to be impaired, and introduction of a hydroxyl group removes a transition metal in a raw material. It is difficult to obtain sufficient permeability, and it is necessary to use expensive raw materials.

[0004]

SUMMARY OF THE INVENTION The present invention does not involve the problems of a decrease in permeability due to the introduction of an oxide and the forced introduction of a hydroxyl group, which are found in the prior art. An object of the present invention is to obtain a product having an effect equal to or higher than that of a product obtained by these methods without increasing raw material costs due to a high-purity raw material. That is, it is to provide a glass having excellent light transmittance up to a shorter wavelength than conventional products, while using raw materials equivalent to the conventional one.

[0005]

Means for Solving the Problems In order to achieve the above object, the present inventor has conducted intensive studies, and as a result, by including NH ₄ F.HF described in the claims, the present inventors have surprisingly shortened the present invention. The inventors have found that the transmittance in the ultraviolet region up to the wavelength is improved, and have accomplished the present invention.

That is, the invention according to claim 1 is a fluorophosphate glass characterized by containing 0.01 to 1% by mole of NH ₄ F.HF as an essential component. the invention according to 2, in _{mol%, P 2 O 5 0.2~25%} , Al 2 O 3 0~10%, AlF 3 0~40%, MgF 2 0~15%, CaF 2 0~30 %, SrF ₂ 0-30%, BaF ₂ 0-25%, ZnF ₂₀ 0-5%, YF ₃ 0-15%, LiF 0-5%, NaF 0-5%, KF 0-5%, NH ₄ F · HF 0.01~ 1%, SiF 4 0~ 2%, PF 5 0~ 5%, MgO 0~ 5%, CaO 0~ 5%, SrO 0~ 5%, BaO 0~ 5%, ZnO 0 Yes _{~ 5%, Y 2 O 3} 0~15%, Li 2 O 0~ 2%, Na 2 O 0~ 2%, K 2 O 0~ 2%, the composition of the The fluorophosphate glass according to claim 1, wherein the atomic ratio of O / F is 0.01 to 2, and the invention according to claim 3 is characterized in that: _{2 O 5 1~20%, Al 2} O 3 0.2~ 7%, AlF 3 7~35%, MgF 2 5~10%, CaF 2 15~30%, SrF 2 12~25%, BaF 2 5 _{~25%, YF 3 0~10%,} NaF 0~ 2%, KF 0~ 3%, NH 4 F · HF 0.01~0.5%, SiF 4 0~ 1%, PF 5 0~ 3% , MgO 0~ 2%, CaO 0~ 2%, SrO 0~ 2%, BaO 0~ 2%, Y 2 O 3 0~ 8%, Na 2 O 0~ 2%, K 2 O 0~ 2%, The fluorophosphate glass according to claim 2, wherein the composition has the following composition: and the atomic ratio of O / F is 0.01 to 1. Is the _{mole%, P 2 O 5 1~20%} , Al 2 O 3 0.2~ 7%, AlF 3 7~35%, MgF 2 5~10%, CaF 2 15~30%, SrF 2 12 _{~25%, BaF 2 5~25%,} YF 3 0~10%, NaF 0~ 2%, KF 0.1~ 2%, NH 4 F · HF 0.01~0.5%, SiF 4 0~ _{1%, PF 5 0.1~ 2%} , MgO 0~ 2%, CaO 0~ 2%, SrO 0~ 2%, BaO 0~ 2%, Y 2 O 3 0~ 8%, Na 2 O 0~ and having _{2%, K 2 O 0~ 2} %, the composition of a fluoride phosphate glass according to claim 3.

The reason for limiting the above composition to the glass having good ultraviolet transmittance according to the present invention will be described below.

[0008] NH ₄ F.HF suppresses the oxidation of glass,
It is effective in preventing the dissolution of the components in the melting vessel, but the amount is 0.1%.
If it is less than 01%, the effect is insufficient, and if it exceeds 1%, the reducing action becomes excessive and the melting vessel may be damaged. Therefore, NH ₄ F · HF is 0.01 to 1
%. Particularly preferred NH ₄ F.HF content is in the range of 0.01 to 0.5%.

The P ₂ O ₅ component is an essential component for forming a glass structure as a glass-forming oxide, and is a component that greatly contributes to the stability of the glass in the fluorophosphate-based glass as in the present invention. In addition to P ₂ O ₅ , various phosphates of other components (eg, Mg (PO ₃ ) ₂ , Ca (PO ₃ ) ₂ and Al (P
O ₃ ) ₃ or the like) can be used as the P ₂ O ₅ raw material. Here, if the amount of P ₂ O ₅ is less than 0.2%, devitrification tends to occur, and if it exceeds 25%, the ultraviolet transmittance decreases, and the target ultraviolet transmittance of the present invention cannot be obtained. . Therefore, in order to obtain a glass having good ultraviolet transmittance without devitrification, the amount of P ₂ O ₅ is limited to 0.2 to 25%. In particular, it is preferably in the range of 1 to 20%.

The Al ₂ O ₃ component is used in various phosphates and oxides such as metaphosphate, orthophosphate, pyrophosphate and the like to improve the chemical durability and devitrification resistance of glass. It is valid. However, if the amount exceeds 10%, the devitrification resistance is rather lowered, and it becomes difficult to obtain a homogeneous glass. When the devitrification resistance and to consider the chemical stability the amount of Al ₂ O ₃ is limited to 0-10%. In particular, it is preferably in the range of 0.2 to 7%.

The AlF ₃ component is the Abbe number (νd) of glass.
However, when the amount exceeds 40%, the devitrification resistance is undesirably lowered. Therefore, the amount of AlF ₃ is limited to 0 to 40%. In particular, it is preferably in the range of 7 to 35%.

MgF ₂ , CaF ₂ , SrF ₂ and BaF ₂
Are also effective in improving the devitrification resistance of the glass, but MgF ₂ is 15% and CaF ₂ is 30%, respectively.
If the content of SrF ₂ exceeds 30% and the content of BaF ₂ exceeds 25%, the devitrification resistance is rather lowered, which is not preferable. Therefore, MgF ₂ is 0 to 15%, CaF ₂ is 0 to 30%, SrF
₂ 0 to 30%, BaF ₂ is limited to 0% to 25%. Particularly, MgF ₂ is 5 to 10%, CaF ₂ is 15 to 30%, Sr
F ₂ is 12 to 25%, BaF ₂ is preferably in the range of 5-25%.

A ZnF ₂ component can be optionally added to improve the devitrification resistance of the glass. However, if the amount exceeds 5%, the glass tends to become unstable. Therefore, Z
nF ₂ amount is limited to 0-5%.

The YF ₃ component is also effective in improving the devitrification resistance of the glass, but when its amount exceeds 15%, this effect can no longer be seen. Therefore, the amount of YF ₃ is 0 to
Limited to 15%. In particular, it is preferably in the range of 0 to 10%.

LiF, NaF and KF are effective components for improving the melting property of the raw material. However, if their amounts exceed 5%, the amount of volatilization during melting increases, making it difficult to obtain a homogeneous glass. Or devitrification tends to occur, which is not preferable. Therefore, each of these components is 0-5
%. In particular, NaF content is 0-2%, KF
Preferably, the amount is in the range of 0-3%. A more preferred amount of KF is in the range of 0.1 to 2%.

Although SiF ₄ is effective in imparting low dispersibility to glass, if its amount exceeds 2%, the tendency of devitrification is remarkably increased, which is not preferable. Therefore, the amount of SiF ₄ is 0
It is limited to the range of ~ 2%. In particular, it is preferably in the range of 0 to 1%.

[0017] PF ₅ components can be used as a double salt with fluorides, such as alkali metal, it is very effective ingredient to the expansion of vitrification range. However, if the amount exceeds 5%, homogenization becomes difficult due to an increase in the amount of volatilization during melting.
In addition, the tendency to devitrify also increases significantly. Therefore, PF ₅ amount is limited to the range of 0-5%. Particularly, it is preferably in the range of 0 to 3%, and more preferably in the range of 0.1 to 2%.

MgO, CaO, SrO, BaO and Z
In nO, a part or all of fluoride is limited to a range of 0 to 5%, respectively. More preferably, it is used by substituting it to the range of 0 to 2%. Particularly preferably, MgO, CaO, SrO
And only BaO is used in the range of 0 to 2%.

Y ₂ O ₃ represents a part or all of YF ₃ from 0 to 1;
It can be substituted and used up to the range of 5%. In consideration of optical performance, stability and the like, the content is preferably in the range of 0 to 8%.

Li ₂ O, Na ₂ O and K ₂ O are Li
Each of F, NaF and KF can be used by substituting it in the range of 0 to 2%. Particularly preferably, Na ₂ O and K ₂
Only O is used in the range of 0 to 2%.

As for the atomic ratio of O / F, it is necessary to contain a large amount of F having a small atomic radius in order to increase the transmittance of ultraviolet rays. When the O / F is 2 or more, F atoms become insufficient and the ultraviolet transmittance cannot be improved. Therefore, the O / F atomic ratio is preferably in the range of 0.01 to 2. In addition, LaF ₃ , NH ₄ F, or the like may be added for adjusting optical constants and improving melting characteristics.

[0022]

EXAMPLES Examples of the present invention are shown in Tables 1 and 2. In particular, Table 1 shows the composition of the glass, the thickness of the glass polished on both sides, of the composition system containing NH ₄ F.HF and the composition system not containing it.
80 in a spectral transmittance curve of a glass sample having a thickness of 80 mm.
The comparison results are shown for% light wavelength, glass refractive index (nd) and Abbe number (νd). FIG. 1 shows a typical example of the content of NH ₄ F · HF and the 80% permeate.

[0023]

[Table 1]

As shown in Table 1, Example No.
Comparative Example N containing no NH ₄ F · HF
o. In all of the samples Nos. 1 to 4, the 80% transmission wavelength tends to be long, indicating the effect of NH ₄ · HF on ultraviolet transmittance.

[0025]

FIG.

As shown in FIG. 1, by adding a small amount of NH ₄ F.HF, the transmittance of ultraviolet rays is significantly improved as compared with the case where no NH ₄ F.HF is added. On the other hand, in the vicinity of 1% addition, the improvement of the transmittance with respect to the addition amount has become slow.

Further, Table 2 shows Examples of the composition of the optical glass according to the present invention, the 80% transmission wavelength, nd and νd.

[0028]

[Table 2]

[Table 2]

[Table 2]

[Table 2]

[Table 2]

[Table 2]

[Table 2]

[Table 2]

[Table 2]

As can be seen from Tables 1 and 2, and FIG.
The fluorophosphate glass of the present invention transmits ultraviolet light well to a short wavelength range.

Each of the glasses of the present invention is weighed and mixed using ordinary optical glass materials such as phosphates, oxides, fluorides, carbonates, nitrates and the like, and this is mixed with a platinum crucible, a quartz crucible or a carbon crucible. It can be easily manufactured by melting, stirring, clarifying and homogenizing at about 850 to 1150 ° C. for about 1 to 5 hours, and then casting it into a mold and cooling.

[0031]

As described above, the fluorophosphate glass of the present invention has a good ultraviolet transmittance up to a short wavelength region.

[Procedure amendment]

[Submission date] August 6, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Added

[Correction contents]

[Brief description of the drawings]

FIG . 1 shows NH ₄ F · HF content and 80% transmission.
It is a figure showing a typical example of the relation of wavelength. ────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] August 7, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0022

[Correction method] Change

[Correction contents]

[0022]

EXAMPLES Examples of the present invention are shown in Tables 1 and 2. In particular, Table 1 shows the composition of the glass and the thickness of both sides polished 10 m for the glass of the composition system containing NH ₄ .HF and the composition system not containing it.
80% transmittance in the spectral transmittance curve of the glass sample m
The results of comparison of the light transmission wavelength, the refractive index (nd) of glass, and the Abbe number (νd) are shown. FIG. 1 shows a typical example of the NH ₄ .HF content and the 80% transmission wavelength .

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction contents]

[0028]

[Table 2]

[Table 2]

[Table 2]

[Table 2]

[Table 2]

[Table 2]

[Table 2]

[Table 2]

Claims (4)

[Claims] 1. A fluorophosphate glass comprising, as an essential component, 0.01 to 1% by mole of NH ₄ F.HF. 2. In mole%, P ₂ O ₅ 0.2-25%, Al ₂ O ₃ 0-10%, AlF ₃ 0-40%, MgF ₂ 0-15%, CaF ₂ 0-30%, SrF ₂ 0-30%, BaF ₂ 0-25%, ZnF ₂₀ 0-5%, YF ₃ 0-15%, LiF 0-5%, NaF 0-5%, KF 0-5%, NH ₄ F. _{HF 0.01~ 1%, SiF 4 0~} 2%, PF 5 0~ 5%, MgO 0~ 5%, CaO 0~ 5%, SrO 0~ 5%, BaO 0~ 5%, ZnO 0~ 5 _{%, Y 2 O 3 0~15%} , Li 2 O 0~ 2%, Na 2 O 0~ 2%, K 2 O 0~ 2%, has the composition, more atomic ratio of O / F 0 The fluorophosphate glass according to claim 1, wherein the fluorinated glass is 0.12. In 3. _{mol%, P 2 O 5 1~20%} , Al 2 O 3 0.2~ 7%, AlF 3 7~35%, MgF 2 5~10%, CaF 2 15~30%, _{SrF 2 12~25%, BaF 2 5~25} %, YF 3 0~10%, NaF 0~ 2%, KF 0~ 3%, NH 4 F · HF 0.01~0.5%, SiF 4 0 _{~ 1%, PF 5 0~ 3} %, MgO 0~ 2%, CaO 0~ 2%, SrO 0~ 2%, BaO 0~ 2%, Y 2 O 3 0~ 8%, Na 2 O 0~ 2 %, K ₂ O 0 to 2%, and the atomic ratio of O / F is 0.01 to 1. 3. In 4. _{mol%, P 2 O 5 1~20%} , Al 2 O 3 0.2~ 7%, AlF 3 7~35%, MgF 2 5~10%, CaF 2 15~30%, _{SrF 2 12~25%, BaF 2 5~25} %, YF 3 0~10%, NaF 0~ 2%, KF 0.1~ 2%, NH 4 F · HF 0.01~0.5%, SiF _{4 0~ 1%, PF 5 0.1~} 2%, MgO 0~ 2%, CaO 0~ 2%, SrO 0~ 2%, BaO 0~ 2%, Y 2 O 3 0~ 8%, Na 2 The fluorophosphate glass according to claim 3, having a composition of O 0 to 2% and K ₂ O 0 to 2%.