JPH01176245A - Glassy thin film - Google Patents

Abstract

PURPOSE:To facilitate the formation of a glassy thin film having high refractive index, by using a Pb-Sn-P-O-F glass as a film-forming material. CONSTITUTION:The objective glassy thin film is a film formed on a substrate and containing Sn, P, Pb, O and F. The composition is preferably composed of 30-90wt.% of Sn, 1-20wt.% of P, 0.1-20wt.% of Pb, 2-30wt.% of O and 5-25wt.% of F. The above glassy thin film can be easily formed into a film by vapor-phase deposition such as evaporation or sputtering and a thin film having a refractive index of >1.65 can be easily produced. The thickness of the glassy thin film is preferably <=40mu, especially <=10mu. The substrate is made of glass, metal, plastic, ceramic or their composite.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a glass-like thin film formed on a substrate such as glass or metal.

[Conventional technology]

Techniques for forming glass thin films on various substrates such as glass, metal, plastic, and ceramic are well known.

The first method is vacuum evaporation. Examples of glass used as a vapor deposition source include Schott No. 83.
No. 29 glass is well known, and is mainly used for vapor deposition using the electron beam method to improve the chemical durability and abrasion resistance of the substrate (Schott Inc. Catalog; Vapor Deposition Glass 8329). As an alternative to the electron beam method, a resistance heating method is also often used, in which a vapor deposition source is placed on a boat made of Mo, Ta, W, etc., and the material is vapor-deposited by supplying electricity.

A second method to replace vapor deposition is high frequency sputtering. This method forms a film on the substrate by bombarding the target with Ar gas using high-frequency output.The glass target used is Corning's 7059.
(Glass Code) Glass is well known. 7o59
The refractive index of the sputtered glass film is 1.544 (λ-thickness 0.6
328 μm), it is possible to fabricate a glass thin film waveguide using quartz, pyrex, soda glass, etc. as a substrate.

(The problem that the invention is trying to solve) However,
In the conventional example described above, the glass used for the vapor deposition source or target had the following drawbacks.

(1) The softening temperature of glass is high and the energy required for vapor deposition is large (softening temperature 8329; 980°C, 7059;
844°C). For example, in the case of electron beam deposition, in order to increase the deposition rate, it is necessary to increase the power of the beam and the capacity of the pump. Furthermore, in vapor deposition by resistance heating, the problem of 0 or more, which requires an increase in heating temperature due to a larger current and voltage, and also an increase in pump capacity, generally becomes more pronounced as the softening temperature becomes higher.

(2) Glass that can be formed into a film is limited, and a glass thin film with a high refractive index cannot be obtained (refractive index of glass film is 832
9; nd-1,47,7059; no, asza
= 1, 544). Schott 8329 and Corning 7059 glass are mainly composed of components such as 5i02.820s that do not contribute to increasing the refractive index, so their refractive index can only be as low as described above, and these two types Since none of the glasses other than the above are actually used for film formation, there is almost no room for selection of the refractive index of the film.

(Means for Solving the Problems) The main object of the present invention is to solve the above-mentioned drawbacks and provide a glassy thin film that is easy to form and has a high refractive index.

The present invention relates to a thin film formed on a substrate, comprising Sn, P,
This is a glass-like thin film characterized by containing the elements Pb, O, and F.

The glass used for the glassy thin film of the present invention is vapor deposited.

The film can be easily formed by a vapor deposition method such as sputtering. In addition, the refractive index after film formation is high, and a glassy thin film having a refractive index greater than 1.65 can be easily formed.

It is well known that Pb-3n-P-0-F glass has a low melting point and has been studied as a direct molding material for aspherical lenses (for example, Physic
s and chantstry of Gl
asses Vol, 25 No. 8 December
er 1984), however, there has been no research to date on the fact that optical thin films with a relatively high refractive index and good chemical durability can be obtained by vapor deposition or sputtering of this type of glass, and on the possibility of its wide range of applications and development. However, the present invention is directed to such Pb-5n-P-0-F.
It has been discovered that the glass-like glass is suitable as a film-forming material, and that the optical properties of the formed glass-like thin film are sufficiently high in terms of refractive index.

The thickness as a glassy thin film is 40μ or less, especially 10μ
The following are preferred.

In addition, the content of each element constituting the glassy thin film is 30 to 90 wt% Sn, 1 to 2 wt% P, and 0.1 wt% Pb.
~20 wt%, 2-3 wt% 0 and 5-25 F
A range of wt% is preferred.

Glass is used as a substrate for forming a glassy thin film.

Metal, plastic, ceramic, or a composite thereof can be used.

(Example) The features of the present invention will be described below based on Examples.

[Example 1] Raw materials (S n
F2, P b Fx, F20S) approx. 300g
and further added 10 wt% NH4 to adjust the atmosphere.
The batch was prepared by adding F-HF. Prepared patch 3
After putting 30g into a silica glass crucible of about 300mft and melting it in an electric furnace maintained at 460t for 1.5 hours,
A transparent glass was obtained by thinly casting on a water-cooled stainless steel vat. As a result of chemical analysis of the cast glass, it was found that it had a composition as shown in b in Table 1. Further, the softening temperature was determined to be 105°C by TMA (thermomechanical analysis).

A vacuum evaporation experiment using a resistance heating method was conducted using a part of the obtained glass b. A quartz glass plate of 1 inch square and 1 inch thick was used as the deposition substrate, and a Ta boat machined into a box shape was used as the heating boat, and about 0.0 mm of glass B was placed in it.
Weighed out 5g and placed it on top. Vapor deposition was carried out under three different conditions, and in vapor deposition condition 1, the film forming rate was high (approximately 50 people/sec).
c) Medium speed for L/, 2 (approximately 15 people/s
e c ), relatively slow in the same 3 (about 2 people/s
The voltage applied to the heating boat was adjusted so that ec). The deposition time was 5 minutes for each, and the thickness was about 1.4 μm under deposition condition 1, and about 0.4 μm under conditions 2 and 3.

A deposited film of approximately 0.05 μm was obtained (deposited film 1, 2°3).

The vapor deposited films 1, 2, and 3 obtained were all transparent, exhibiting grayish brown, brownish brown, and pale yellow colors, respectively, and had a refractive index (n,)
were 1.83°1.81 and 1.79, respectively.

Moreover, as a result of chemical analysis of the obtained thin film, the deposited film 1.2.
It was found that the compositions of No. 3 were as shown in Table 2. Although the film composition varies depending on the film forming conditions, it can be seen that all components contained in the glass of the vapor deposition source are contained in the vapor deposited film except for the impurity St.

Furthermore, when we performed X-ray diffraction on the deposited film 1.2, it was found that the deposited film 1.2 contained microcrystals of Sn2P2ot and pbHzPzOs, but metal phases such as Sn and Pb were not detected. . Since the deposited film 3 was thin, it was not possible to identify the presence or absence of crystals.

From the above results, even though the deposited films 1 and 2 contain a large amount of F, since there are no fluoride crystals, F is incorporated into the glass structure as shown in Table 1 and Table 2 [Example 2] The deposited film 1 produced in Example 1 was irradiated with an electron beam using an electron beam microanalyzer. Experimental conditions were acceleration voltage 1
5KV, sample current 0.02μA, electron beam diameter approximately 2μ
I narrowed it down to m. It was confirmed that the deposited film was easily deformed after irradiation time of 2 seconds, and pits of about 2 μmφ were formed.

[Example 3] A 1-inch substrate with vapor-deposited film 1.2.3 produced in Example 1 was left for one week in an atmosphere of 50°C and 98% relative humidity, but no corrosion was observed on the film surface and the weight The decrease is also 0.
01% or less, which was within the measurement error.

〔Effect of the invention〕

As explained above, the novel thin film according to the present invention has the following advantages.

(1) Vapor deposition and sputtering can be performed at relatively low temperatures and low energy, and the cost is low.

(2) A glass thin film with a considerably higher refractive index than conventionally known glass thin films can be obtained. Therefore, there is a possibility of application to glass waveguides.

(3) It is a thin film that can be written with lower energy than ever before. This can be said to be a characteristic effect of using Pb-3n-P-0-F glass as a deposition source.

(4) Since it has excellent water resistance, it can also be used as a surface protective film.

Claims (4)

[Claims] (1) A thin film formed on a substrate of Sn, P, and Pb
, O, and F. (2) Sn is 30 to 90 wt%, P is 1 to 20 wt%,
The glassy thin film according to claim 1, containing 0.1 to 20 wt% of Pb, 2 to 30 wt% of O, and 5 to 25 wt% of F. (3) Claim 1 where the refractive index is greater than 1.65
The glassy thin film described in Section 1. (4) The glassy thin film according to claim 1, which is formed by a vapor deposition method.