JPS6155603A - High-durability infrared reflecting mirror - Google Patents

Abstract

PURPOSE:To obtain substantial durability and good optical performance by forming the film of the 1st layer consisting of Cr, Ti, Co or Ni on a substrate and forming the film of the 2nd layer consisting of TiN thereon. CONSTITUTION:The film 2 of the 1st layer consisting of one among Cr, Ti, Co and Ni or the mixture composed thereof is formed on the substrate 1 and the film 3 of the 2nd layer consisting of TiN is disposed thereon. These films are preferably so formed that the thickness d1 of the film 2 and the thickness d2 of the film 3 have the relation 1<=(d1/d2)<=10. Good reflectivity of about 90% is obtd. by forming a reflecting mirror consisting of Ti, etc. to the material of the film 2 in the above-mentioned manner. The film 3 consisting of TiN has excellent chameical stability and wear resistance and makes the mirror usable under severe conditions. The internal stress over the entire part of the film is made small and the decrease in the surface accuracy of the reflecting mirror is prevented by setting the thickness ratio of the films 2, 3 in the above-mentioned manner. The IR reflecting mirror having the excellent durability in the wear resistance, chemical stability, etc. and good optical characteristic is thus obtd.

Description

[Detailed description of the invention] [Technical field] The present invention relates to a reflector in the infrared wavelength region.

[Prior art] Conventionally, as a reflector in the infrared region, an FJ made of metal such as aluminum, gold, silver or copper is used on a substrate such as glass.
Those marked with M are used. However, all of these metal film reflectors have low abrasion resistance and, with the exception of gold film reflectors, have low chemical stability.

Therefore, in order to compensate for this drawback, a protective film made of MgF2, SfO, etc., which is transparent in the infrared region, is provided on the metal film. However, when applying such a protective film, a thin film is insufficient, and unless a fairly thick film is applied, durability such as abrasion resistance and chemical stability will not be sufficient. For this reason, a relatively thick film must be applied, but as the thickness of the protective film increases, not only does the spectral reflectance decrease, but also the internal stress of the film increases, deforming the substrate and affecting optical performance such as surface accuracy. There was a problem that the value decreased.

[Object of the Invention] In view of the prior art as described above, an object of the present invention is to provide an infrared reflecting mirror having sufficient durability and good optical performance.

[Summary of the Invention] According to the present invention, the above-mentioned purpose is to
A first i-th film made of one of i, Co, and Ni or a mixture thereof is formed, and a second-layer film made of TiN is formed on the second-layer film. This is achieved using a highly durable infrared reflector that is characterized by

[Embodiments of the Invention] Specific embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic cross-sectional view of a highly durable infrared reflecting mirror according to the present invention. In FIG. 1, l is a glass substrate, and 2 is a first
It is the second layer ■profit, and 3 is the second layer TiNII! f! In this example, Ti was used as the material for the first layer film. The thickness of the first layer film 2 is 0.81
Lm, and the film thickness of the second layer nλ was 0.3 m.

The film formation for the first layer of Doi is carried out by the usual vacuum evaporation method. After evacuating to a vacuum level of 1X10-8 Torr, metal Ti is deposited to a thickness of 0 using an electron gun evaporation source while the substrate temperature is maintained at about 300"0. For the second layer, which was deposited at 8 lumen, nitrogen gas was introduced as a reaction gas to 4 x 10-'Torr, and metal Tf was evaporated by an electron gun evaporation source while activated by plasma discharge. A TiN film with a thickness of 0.3 m was formed by rating.

FIG. 2 is a graph of the spectral characteristics of the reflecting mirror of this example. As a result, the reflector of this embodiment has a 90% efficiency in the infrared region.
It can be seen that the reflectance is fairly good, and the longer the wavelength, the higher the reflectance.

Similarly, the material of the first layer film is Cr other than Ti.
A reflecting mirror was created using metals such as , Co, Ni, and a mixture of these metals including Ti, with a film thickness of 0.8 pm, and a second layer TiN film thickness of 0.3 m. As a result, all of them showed the same spectral characteristics as shown in FIG. 2, and a good reflectance of about 90% in the infrared region could be obtained.

Since the TiN11 port 3 of the second layer of VJ has excellent chemical stability and wear resistance, the reflective mirror of the present invention can be used even under severe conditions.

In the reflective mirror of the present invention, the first layer of metal film has tensile stress when formed by vacuum evaporation, while the second layer of TiN1l has compressive stress when formed by ion blasting or sputtering. Therefore, by appropriately setting the film thickness of the first layer film and the m thickness of the second layer film, it is possible to reduce the internal stress of the film as a whole. This has the effect of preventing a decrease in accuracy. For this purpose, it is necessary to take into account that the internal stress of the TiN film is several times larger than the internal stress of the metal film.
In the reflective mirror of the present invention, the film thickness of the first layer and the second layer are
The difference between the film thickness of the layer and the film thickness is ≦(dt/d2)≦l
It is preferable that there is a relationship of O.

[Effects of the Invention] According to the present invention as described above, an infrared reflecting mirror having good durability such as abrasion resistance and chemical stability and good optical performance is provided.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an infrared reflecting mirror of the present invention. FIG. 2 is a graph of its spectral characteristics. 1... Substrate 2... First layer film 3... Second
! J-th TiN film

Claims (2)

[Claims] (1) A first layer film made of one of Cr, Ti, Co, and Ni or a mixture thereof is formed on the substrate, and a first layer film made of TiN is formed on the second layer film. A highly durable infrared reflecting mirror characterized by having a second layer film formed thereon. (2) Highly durable red according to item 1, where there is a relationship of 1≦(d_1/d_2)≦10 between the film thickness d_1 of the first layer film and the film thickness d_2 of the second layer film. External reflector.