KR20020055357A - Reflection layers for optical storage media, optical storage media and sputtering targets for reflection layer of optical storage media - Google Patents

Abstract

PURPOSE: To provide a new reflection layer for an optical information recording medium having high reflectance, excellent sulfur resistance and good adhesion property with a disk substrate (polycarbonate substrate or the like) and other thin films constituting the disk. CONSTITUTION: The reflection layer for an optical information recording medium consists of an Ag alloy containing >=1.5 at.% Zn.

Description

REFLECTION LAYERS FOR OPTICAL STORAGE MEDIA AND OPTICAL STORAGE MEDIA AND SPUTTERING TARGETS FOR REFLECTION LAYER OF OPTICAL STORAGE MEDIA}

The present invention is a reflective layer for an optical information recording medium having excellent sulfidation resistance or adhesion to a disk substrate (such as a polycarbonate substrate) and other thin films constituting the disk (hereinafter referred to as "adhesion to a substrate") (for optical discs). Reflecting layer), an optical information recording medium, and a sputtering target for a reflective layer of the optical information recording medium. Since the reflective layer of the present invention has high reflectance, phase-change optical disks (optical disks capable of repeating recording and reproducing) such as CD-RW, DVD-RAM, DVD-RW, DVD + RW, etc .; It is suitably used for write-once optical discs such as CD-R and DVD-R.

There are several types of optical discs, but representative examples of the optical recording medium having a recordable area capable of recording directly to the disc include phase change type discs and write-once discs.

Among them, the phase change type optical disk controls the intensity and irradiation time of the laser light to form two-phase states of the crystal phase and the amorphous phase in the recording thin film layer to record data and to detect (reproduce) the data by detecting the change in reflectance of the two phases. . This recording and reproducing method can be repeatedly recorded and reproduced. As an optical disc employing such a method, CD-RW, DVD-RAM, DVD-RW, DVD + RW, and the like can be given.

The phase change type optical disc is formed by stacking a substrate and various thin film layers such as a dielectric thin film layer, a recording thin film layer, a reflective thin film layer, and a protective film layer on the substrate. Since the double reflective thin film layer also serves as a heat dissipating thin film layer, the reflective thin film layer material is required to have good characteristics such as reflectance, thermal conductivity, durability against thermal shock, corrosion resistance, and adhesion to a substrate. In particular, in order to improve the recording density in high density recording, the thermal conductivity of the reflective heat radiation layer must be large. However, there is still no material for the reflective layer that satisfies these required characteristics.

For example, Al alloys widely used as reflective thin film materials have relatively high reflectance and corrosion resistance (chemical corrosion resistance) with respect to laser wavelengths (780 nm and 650 nm) used for recording and reproduction. The disadvantages are insufficient and low thermal conductivity. Therefore, it is difficult to use the Al alloy in the reflective thin film layer to have all the characteristics required for the reflective layer, and as a result, the structure and the design of the disk have been restricted.

Therefore, it was proposed to use Au, Ag, Cu as a reflective thin film material instead of Al alloy, but this also has the following problems. For example, pure Au or alloys based mainly on Au can achieve high reflectivity, high corrosion resistance and high thermal conductivity, but Au is very expensive and not practical. On the other hand, although pure Ag or pure Cu, or alloys containing Ag or Cu as a main component are inexpensive, they all have a drawback that they are poor in corrosion resistance. In addition, pure Cu or an alloy containing Cu as a main component has a problem of poor corrosion resistance, particularly oxidation resistance, and as a result, there is a fear of causing a decrease in reliability (durability) of the disk. In addition, pure Ag or an alloy containing Ag as a main component has a problem in that corrosion resistance, in particular, sulfidation resistance is poor.

Of these, the last published sulfurization resistance is a characteristic required for both phase change type and recordable type (described below) optical discs. In the phase change type optical disk, the dielectric thin film layer and the reflective thin film layer are in direct contact with each other. Among them, ZnS-SiO ₂ film is generally used. Therefore, when pure Ag or Ag-based alloy is used as the reflective thin film layer, S in the dielectric thin film and Ag in the reflective thin film react at the interface for a long time. AgS is generated. As a result, various characteristics required for the reflective thin film layer deteriorate, and finally the recording / reproducing characteristic of the disc is remarkably impaired.

In addition, when each material of Au, Ag, Cu is used, all of these materials have a problem of poor adhesion to a substrate or the like. In the reflective heat dissipation layer of the optical disc, the adhesive force is reduced with other thin films in contact with the interface of the reflective heat dissipation layer due to the thermal shock caused by the heat cycle along with repetitive recording. As a result, the effective thermal conduction decreases or the thermal conduction unevenness occurs, and finally, jitter or the like increases, which significantly degrades the recording and reproduction characteristics of the disc.

On the other hand, the write-once optical disk generates heat and deteriorates the pigments in the recording thin film layer (organic dye layer) by the intensity of the laser beam, deforms the grooves (grooves inscribed in advance on the substrate) to record data, and reflectance of the deformed portion and Data detection (reproduction) is performed by detecting a difference in reflectance of the undeformed portion. This recording / reproducing method has a feature that data once recorded can not be used again (once limited recording and repeated playback), and CD-R, DVD-R, and the like can be cited as the optical disk employing this method.

In addition, the problems discussed in relation to the phase change type disk also appear in the reflective thin film layer of the recordable disk.

In the write-once optical disc, an alloy containing Au or Au as a main component is widely used as a material for the reflective thin film layer. These materials can achieve high reflectance of 70% or more even if an organic dye layer is present with respect to the laser wavelengths (780 nm, 650 nm) used for recording and reproduction. However, Au is very expensive, and is a major cause of cost increase.

Therefore, it is proposed to use Ag, Cu, Al as the reflective thin film material instead of the above material. However, alloys containing pure Ag and pure Cu as main components have the disadvantage that corrosion resistance is poor as described above. In addition, pure Ag or an alloy containing Ag as a main component has problems of corrosion resistance, in particular, sulfidation resistance. Unlike the phase change type optical disk, the write-once optical disk does not have a dielectric thin film layer mainly composed of ZnS-SiO ₂ , but an S additive material may be used in the organic dye layer. In this case, since the recording thin film layer and the reflective thin film layer are in direct contact with each other, Ag in the reflective thin film reacts with S to become sulfide, and as a result, the reflectance is lowered. In addition, pure Al or an alloy containing Al as a main component has a problem that the reflectance is low and high reflectance of 70% or more cannot be achieved when an organic dye layer is present.

In both of the phase change type and the write-once type, the reflective thin film layer of the optical disc satisfies all of the required characteristics, although the reflectance, thermal conductivity, durability against thermal shock, corrosion resistance and adhesion to the substrate are required to be excellent. No metal thin film layer is provided yet.

The present invention is to solve the problems of the prior art, and not only exhibits a high reflectance, but also particularly excellent in sulfidation resistance and good adhesion to disk substrates (such as polycarbonate substrates) and other thin films constituting the disk. It is an object of the invention to provide a reflective layer for an optical information recording medium, an optical information recording medium and a sputtering target for a reflective layer of the optical information recording medium.

1 is a graph showing the relationship between the alloying element addition amount and the initial reflectance of the Ag-based alloy reflective thin film layer of Example 2 of the present application.

FIG. 2 is a graph showing the relationship between the amount of alloy element addition and the amount of reflectance reduction of the Ag-based alloy reflective thin film layer of Example 2 of the present application. FIG.

3 is a graph showing the relationship between the Zn addition amount and the initial reflectance of the Ag-based alloy reflective thin film layer of Example 4 of the present application.

4 is a graph showing the relationship between the amount of Zn addition and the amount of reflectance reduction with respect to the Ag-based alloy reflective thin film layer of Example 4 of the present application.

FIG. 5 is a graph showing the relationship between the amount of the third component added and the initial reflectance of the Ag-Zn alloy reflective thin film layer of Example 8 of the present application. FIG.

FIG. 6 is a graph showing the relationship between the amount of the third component added and the amount of reflectance reduction with respect to the Ag—Zn alloy reflective thin film layer of Example 8 of the present application. FIG.

FIG. 7 is a graph showing the relationship between the amount of the third component added and the amount of reflectance reduction with respect to the Ag—Zn alloy reflective thin film layer of Example 8 of the present application. FIG.

8 is a graph showing the relationship between the amount of the third component added and the tensile strength of the Ag-Zn alloy reflective thin film layer of Example 10 of the present application.

The reflective layer for an optical information recording medium of the present invention which can solve the above problems is made of an Ag-based alloy containing 1.5% or more of Zn. Here, the Ag-based alloy containing 0.5 to 5% of one or more elements selected from the group consisting of Cu, Ti, Nd, W, Mo, Sn and Ge is one of the preferred embodiments for improving adhesion to a substrate or the like. and; In addition, the Ag-based alloy contains 0.5 to 3% of at least one element selected from the group consisting of Cu, Ni, Au, Y and Nd is a preferred embodiment for improving reflection characteristics and oxidation resistance.

Further, the optical information recording medium including the reflective layer for the optical information recording medium, and the sputtering target for the reflective layer of the optical information recording medium composed of the Ag-based alloy also fall within the scope of the present invention.

MEANS TO SOLVE THE PROBLEM The present inventors earnestly examined in order to improve the adhesiveness with respect to the sulfide-resistant, or the disk substrate (polycarbonate board | substrate etc.) and the other thin film which comprises a disk among the characteristics required for the reflective layer for optical information recording media. As mentioned above, the conventional reflective layer material uses Al alloy to improve the corrosion resistance (especially sulfidation resistance) in the phase change type optical disk; This is because pure Au or pure Ag is used to improve the reflectance and the corrosion resistance (particularly the chemical stability) in the write-once optical disc, but the desired characteristics have not yet been obtained.

Specifically, the present inventors used Ag-based alloy sputtering targets prepared by adding various elements to Ag, formed Ag-based alloy thin films having various component compositions by sputtering, and evaluated the characteristics as reflective thin film layers. As a result, the Ag-based alloy thin film containing a predetermined amount of Zn is very excellent in sulfidation resistance; In addition, in the Ag-Zn alloy, the addition of at least one element selected from the group consisting of Cu, Ni, Au, Y and Nd further improves reflection properties and corrosion resistance (especially oxidation resistance); In addition, in the Ag-Zn alloy, it has been found that the addition of one or more elements selected from the group consisting of Cu, Ti, Nd, W, Mo, Sn, and Ge significantly improves the adhesion, thereby completing the present invention. Reached.

In general, the reflectance tends to decrease when adding an alloying element to Ag as compared to the case of pure Ag. However, when the composition and the amount of addition of the alloy are properly adjusted as in the present invention, the reduction of the reflectance can be controlled within the allowable range, and the characteristics such as sulfidation resistance and adhesion can be achieved at a high level as compared with the prior art. It became possible.

In the following, requirements for configuring the reflective layer for the optical information recording medium of the present invention will be described.

First, the reflective layer of the present invention is composed of an Ag-based alloy containing 1.5% or more of Zn. That is, the most important part of the present invention is to clarify that the addition of Zn to the Ag-based alloy 1.5% or more significantly improve the sulfidation resistance.

According to the results of the present inventors, first, as the Ag-Zn alloy thin film, the more Zn addition amount, the higher the sulfidation resistance was. Specifically, when the amount of Zn added is in the range of 0 to 1.5%, the higher the amount of Zn, the better the sulfidation resistance and the synergistic effect of the sulfidation by Zn addition is very remarkable, but the effect starts to slow down when the amount of Zn exceeds 1.5%. If it exceeds 5%, it is almost saturated, so adding more than this is uneconomical. However, considering the relationship with the reflection characteristic, it is preferable to set the upper limit to 5% (more preferably 3%). This is because, when the reflectance of the Ag-Zn alloy thin film is examined, the reflectance tends to decrease as the amount of Zn added increases (see Examples described later). Therefore, in order to ensure excellent sulfidation resistance while maintaining high reflectance, it is preferable to control the amount of Zn added in the range of 1.5 to 5%.

On the other hand, in the conventional reflective layer for optical information recording media, there is an example in which an Ag-Zn-based alloy is used. However, the fact that sulfidation resistance can be improved by adding a predetermined amount Zn as in the present invention has not been found in the prior art.

For example, Japanese Patent Laid-Open No. 98-11799 discloses an optical recording medium having Ag as a main component as a light reflection layer. However, even if the above publication is examined in detail, only Zn is recognized as a non-pure substance, and only the amount of addition is determined based on the general principle of "not reducing the reflectance". Further, Japanese Patent Laid-Open No. 99-154354 discloses an optical recording medium obtained by adding Ag and Cu to a reflective heat dissipating layer and further adding Zn. Although the above publication discloses that the corrosion resistance of the Ag-Cu-based reflective heat dissipation layer is improved by the addition of Zn, furthermore, the fact that Zn is effective for improving the sulfidation resistance as in the present invention is further described. It is not implied at all.

In the field of optical information recording media, it is not known until now that Zn is added for the purpose of improving the sulfidation resistance, and it has been found for the first time by the present inventors. .

On the other hand, in the present invention, it is selected from the group consisting of Cu, Ni, Au, Y and Nd for the purpose of further improving the basic properties (i.e., reflectance and corrosion resistance (oxidation resistance)) required for the reflective layer for the optical information recording medium. It is preferable to contain 0.5-3% (more preferably 0.5-2%) of 1 or more types of elements in total. If the total addition amount of these elements is less than 0.5%, the above effect is not sufficiently exhibited. On the other hand, if the total addition amount of the above element is more than 3%, the above action is deteriorated, and the performance as a reflective layer for an optical information recording medium deteriorates.

On the other hand, the preferable addition amount of each element differs slightly because the effect expression region differs among the said elements. Specifically, it is preferable to control within the ranges of Cu: 0.5 to 2%, Ni: 0.5 to 2%, Au: 0.5 to 1.5%, Y: 1 to 3%, and Nd: 1 to 3%. It is because it can maintain the high reflectance of the grade equivalent to using the pure Ag thin film within the said range.

In addition, although the said element may be used individually or in combination of 2 or more types, it is preferable to add Au at least. This is because, as the amount of Au added increases, in particular, the sulfidation resistance is improved. In consideration of the fact that Au is expensive and the addition of a large amount leads to an increase in cost, it is preferable to control it in the range of 0.5 to 1.5% as described above, thereby exhibiting the desired characteristics at a minimum cost.

In addition, in the present invention, in order to improve adhesion to a substrate or the like, in the Ag-Zn-based alloy, at least one element selected from the group consisting of Cu, Ti, Nd, W, Mo, Sn, and Ge may be 0.5 to 5 in total. It is preferable to add in 3% (more preferably, 0.5 to 2%). When the total addition amount of these elements is less than 0.5%, the above effect is not sufficiently exhibited. On the other hand, when the total addition amount of the elements exceeds 3%, the above action is deteriorated, and the performance as a reflective layer for an optical information recording medium deteriorates.

On the other hand, the preferable addition amount of each element differs slightly because the effect expression region differs among the said elements. Specifically, Cu: 0.5 to 3%, Ti: 0.5 to 2.0%, Nd: 1.0 to 3.0%, W: 0.5 to 1.0%, Mo: 0.5 to 1.0%, Sn: 05 to 2.0%, Ge: 0.5 to It is preferable to control in 3.0% of range.

The reflective layer for an optical information recording medium of the present invention contains the above components and the remainder is Ag, but other components other than the above components may be added within a range that does not impair the operation of the present invention. For example, for the purpose of imparting properties such as hardness improvement, precious metals such as Pd and Pt and transition elements (except as described above) may be actively added. Also, O _2, it does not matter even if the water is not pure water that is already included in the gas composition or soluble material of Ag-Zn-based alloy, such as N ₂ is contained.

In the present invention, the Ag-based alloy composed of the above-mentioned component composition is preferably formed by sputtering. Elements [Sulfurization Resistance Enhancement Elements (Zn), Adhesive Enhancement Elements (Cu, Ti, Nd, W, Mo, Sn, Ge), Reflective Properties and Oxidation Resistance Enhancement Elements (Cu, Ni, Y, Nd) Used in the Present Invention ], Although the solid melting limit for Ag is very small in equilibrium (on the other hand, Au melts solid in the whole range), the thin film formed by sputtering enables non-equilibrium solid melting due to sputtering inherent gas phase quenching. This is because the alloying element is present uniformly in the Ag matrix as compared with the case where the Ag-based alloy thin film is formed by other thin film forming method, and as a result, the sulfidation resistance and adhesion are remarkably improved.

Moreover, it is preferable to use Ag type alloy (henceforth a "solvent Ag type alloy target material") manufactured by the dissolution and casting method as a sputtering target material at the time of sputtering. Since the solvent Ag-based alloy target material is uniform in structure and uniform in sputtering rate and exit angle, the Ag-based alloy thin film (reflective metal layer) having a uniform composition can be stably obtained to produce a higher performance optical disk. On the other hand, when the oxygen content of the solvent Ag-based alloy target material is controlled to 100 ppm or less, it is easy to maintain a constant film formation rate and the oxygen content of the Ag-based alloy thin film is also lowered, so that the reflectance and corrosion resistance of the Ag-based alloy thin film (particularly, Sulfurization resistance) can be significantly increased,

The present invention is described in detail based on the following examples. However, the following Examples do not limit the present invention, and any modifications made within the scope of the preceding and the following are included in the technical scope of the present invention.

Example 1

In this embodiment, the reflectance and the amount of change in reflectance before and after the high temperature and high humidity test of various Ag binary alloy thin films were investigated.

First, a transparent polycarbonate resin substrate (substrate size: 50 mm in diameter, thickness) using an Ag bicomponent alloy target (containing 2.0% of various alloy elements) composed of various component compositions shown in Table 1 by DC magnet long sputtering A sample in which various Ag bicomponent alloy thin films (reflective thin film layers) having a thickness of 1000 kHz were formed on 1 mm). Next, the reflectance (spectral reflectance) in the measurement wavelength: 800-200 nm was measured about the said sample. The reflectance was measured on the reflective thin film layer side. Table 1 describes the reflectance at wavelength 800 nm and the reflectance at wavelength 390 nm in various Ag-based alloy thin films.

No. Alloy reflectivity(%) Measurement wavelength: λ = 800 nm Measurement wavelength: λ = 390 nm One Ag-2.0% Zn 91.9 73.9 2 Ag-2.0% Ti 93.7 84.7 3 Ag-2.0% W 92.9 82.6 4 Ag-2.0% Mo 93.1 85.2 5 Ag-2.0% Sn 96.6 92.7 6 Ag-2.0% Ge 92.0 82.8 7 Ag-2.0% Cu 98.6 77.9 8 Ag-2.0% Ni 97.8 90.5 9 Ag-2.0% Au 99.7 92.3 10 Ag-2.0% Y 98.8 84.2 11 Ag-2.0% Nd 97.5 85.9 12 Pure Ag 98.3 88.3 13 Ag-2.0% Al 96.4 71.4 14 Ag-2.0% Ga 94.9 97.6 15 Ag-2.0% In 94.7 95.3 16 Ag-2.0% Pd 95.7 86.9 17 Ag-2.0% Pt 92.8 81.3

In Table 1, the Ag binary alloys of Nos. 1 to 11 all exhibit high reflectivity of 90% or more at a wavelength of 800 nm and 70% or more at a wavelength of 390 nm, and are of the same level as the Ag binary alloys of Nos. 12 to 17. It can be seen that it has an excellent reflectance. Among them, the Ag bicomponent alloy to which Sn, Cu, Ni, Au, Y, and Nd elements were added was particularly high in initial reflectance (reflectance of the thin film immediately after film formation by sputtering).

Next, using the sample, a high temperature and high humidity test (performed for 48 hours at a temperature of 80 ° C. and a humidity of 90% RH) was performed as an environmental acceleration (load) test, and the corrosion resistance (oxidation resistance) of the reflective thin film layer was evaluated. Specifically, the corrosion resistance (oxidation resistance) was evaluated by measuring the reflectance (spectroreflectivity) of the reflective thin film layer for each sample after the completion of the high temperature and high humidity test, and calculating the difference between the reflectances before and after the test (that is, the decrease in the reflectance after the end of the test). . Table 2 shows the change in reflectance at a wavelength of 800 nm and the change in reflectance at a wavelength of 390 nm when various Ag-based alloy thin films were subjected to a high temperature and high humidity test.

No. Alloy Reflectance change (△%) Measurement wavelength: λ = 800 nm Measurement wavelength: λ = 390 nm One Ag-2.0% Zn +2.5 -6.0 2 Ag-2.0% Ti +2.5 -4.0 3 Ag-2.0% W -1.4 -5.8 4 Ag-2.0% Mo -1.2 -5.6 5 Ag-2.0% Sn -5.8 -15.0 6 Ag-2.0% Ge -16.1 -5.3 7 Ag-2.0% Cu -0.4 -6.7 8 Ag-2.0% Ni -0.4 -5.3 9 Ag-2.0% Au -0.7 -2.6 10 Ag-2.0% Y +1.5 +5.0 11 Ag-2.0% Nd +2.1 +8.7 12 Pure Ag -1.0 -9.6 13 Ag-2.0% Al -3.7 -15.7 14 Ag-2.0% Ga -16.1 -5.3 15 Ag-2.0% In -11.2 -8.9 16 Ag-2.0% Pd -0.7 -2.4 17 Ag-2.0% Pt -0.9 -1.3

Of the samples provided in the experiment, in particular Zn, Ti. It can be seen that the Ag-based alloy containing each element of Cu, Ni, Au, Y, and Nd has a small amount of reduction in reflectance and is excellent in corrosion resistance (oxidation resistance).

On the other hand, considering the results of Table 1 and Table 2 in terms of securing high reflectivity and high corrosion resistance (high oxidation resistance), in particular, Ag-Cu, Ag-Ni, Ag-Au, Ag-Y, It can be seen that the use of Ag-Nd-based alloy thin films is preferable.

Example 2

In the present Example, the initial reflectance and the reflectance change amount before and after a high temperature, high humidity test when the addition amount of the alloy in the Ag bicomponent alloy thin film was varied were investigated.

First, in Example 1, five kinds of thin films excellent in reflectance and corrosion resistance, that is, Ag-Cu based, Ag-Ni based, Ag-Au based, Ag-Y based, and Ag-Nd based thin films, The reflectance (spectral reflectance) in the range of the measurement wavelength 800-200 nm was measured, changing the addition amount of an alloying element. The reflectance was measured on the reflective thin film layer side. 1 shows the relationship between the amount of alloy addition and the initial reflectance at a wavelength of 700 nm.

In Fig. 1, both of the Ag-based alloy thin films had an initial reflectance of about 99% or more in the range of 0 to 1% of the alloy element addition, and had very high reflectances equivalent to or higher than those of pure Ag thin films. On the other hand, when the addition amount of the alloying element exceeds 1%, the initial reflectance gradually begins to decrease, but even when 5% is added, the initial reflectance was maintained at about 95% or higher.

Next, with respect to the sample, the corrosion resistance (oxidation resistance) of the reflective thin film layer was evaluated in the same manner as in Example 1, and the relationship between the corrosion resistance and the alloying element addition amount was investigated. Fig. 2 shows the relationship between the reflectance at the wavelength of 700 nm and the amount of alloying elements added to the Ag alloy thin film before and after the high temperature and high humidity test.

In Fig. 2, both of the Ag-based alloy thin films have a smaller amount of reduction in reflectance than pure Ag, which shows that the corrosion resistance (oxidation resistance) is improved over alloying. On the other hand, the corrosion resistance tends to be the maximum at around 1% of the alloy element addition, and generally decreases when the addition amount exceeds 1%. However, when 3% or more is added depending on the type of alloy, the corrosion resistance is lowered compared to pure Ag. Considering that it has been shown, it is preferable to control the amount of alloying element added in the range of 0.5 to 3%.

Example 3

In this Example, hydrogen sulfide (H ₂ S) atmosphere exposure test was performed on various Ag binary alloy thin films to evaluate sulfidation resistance.

First, a sample in which various Ag binary alloy thin films (reflective thin film layers) were formed by the same method as Example 1 using various Ag binary alloy targets (containing 2.0% of alloy elements) shown in Table 3 was prepared. The reflectance (spectral reflectance) in the range of the measurement wavelength 800-200 nm was measured. Next, the an environmental accelerated test as to sample hydrogen sulfide atmosphere exposure test "Atmosphere: Air _{+ H 2 S (50 ppm)} , temperature 50 ℃, subjected to humidity 90% RH] were evaluated in hwanghwaseong the reflective thin film layer. Specifically, the sulfidation resistance was evaluated by measuring the reflectance (spectral reflectance) of the reflective thin film layer with respect to the sample after the end of the test, and calculating the difference between the reflectances before and after the test (that is, the decrease in the reflectance after the end of the test). Table 3 recorded the reflectance change amount in wavelength 800nm and the reflectance change amount in wavelength 390nm about the Ag-type alloy thin film before and behind hydrogen sulfide atmosphere exposure test.

No. Alloy Reflectance change (△%) Measurement wavelength: λ = 800 nm Measurement wavelength: λ = 390 nm One Ag-2.0% Zn -22.6 -38.4 2 Ag-2.0% Ti -75.3 -65.8 3 Ag-2.0% Cu -78.1 -64.2 4 Ag-2.0% Ni -84.6 -79.4 5 Ag-2.0% Au -36.7 54.6 6 Pure Ag -91.6 -63.2 7 Ag-2.0% Al -43.2 -73.3 8 Ag-2.0% Mg -49.7 -70.1 9 Ag-2.0% Pd -40.5 -73.7 10 Ag-2.0% Pt -25.6 -46.4

In Table 3, since the Ag-based alloy thin film (No. 1) containing Zn has the smallest reflectance reduction compared to other Ag-based alloy thin films, it can be seen that the Ag-Zn-based alloy has excellent sulfurization resistance. .

Example 4

In this embodiment, the Ag-Zn alloy thin film was subjected to a hydrogen sulfide atmosphere exposure test to investigate the amount of change in reflectance.

First, a sample in which an Ag-Zn bicomponent alloy thin film (reflective thin film layer) was prepared by varying the amount of Zn added in the same manner as in Example 1 was prepared, and then the reflectance in the range of 800 to 200 nm (spectral reflectance) was measured. Was measured. 3 shows the relationship between the amount of Zn addition and the initial reflectance at the wavelength of 700 nm.

In FIG. 3, in the Ag-Zn alloy thin film, the initial reflectance tends to decrease as the amount of Zn added increases. However, even when 5% of Zn is added, the Ag-Zn alloy thin film has a high reflectance of 85% or more.

Next, with respect to the sample, the sulfidation resistance of the reflective thin film layer was evaluated in the same manner as in Example 3, and the relationship between the sulfidation resistance and the amount of Zn addition was investigated. 4 shows the relationship between the reflectance decrease amount and the Zn addition amount at a wavelength of 700 nm for the Ag-Zn alloy thin film before and after the hydrogen sulfide atmosphere exposure test.

In FIG. 4, it can be seen that the sulfidation resistance is improved by the addition of Zn in that the reflectance decrease gradually decreases as the Zn addition amount is increased. In detail, the Zn-added amount of 0-1.5% shows a significant improvement in sulfidation resistance by Zn addition, but the effect starts to slow down when the Zn-added amount exceeds 1.5% and is almost saturated when it exceeds 5%.

In view of the above, it can be seen that, in view of the results of FIGS. 3 and 4, when the amount of Zn added in the Ag—Zn alloy thin film is controlled in the range of 1.5 to 5%, sulfidation resistance is also improved while maintaining a high initial reflectance.

Example 5

In the present Example, the adhesiveness of various Ag type alloy thin films was evaluated by the patterning test.

First, a sample in which various Ag bicomponent alloy thin films (reflective thin film layers) shown in Table 4 were formed in the same manner as in Example 1 was prepared. Next, the whole surface of the said sample was processed into the stripe shape of width 10micrometer by photolithography and wet etching, and adhesiveness was evaluated by observing the stripe presence or absence after processing with an optical microscope. The results are shown in Table 4.

No. Alloy Evaluation result (peeled state) One Ag-2.0% Zn Peeling 2 Ag-2.0% Ti No peeling 3 Ag-2.0% W No peeling 4 Ag-2.0% Mo No peeling 5 Ag-2.0% Sn No peeling 6 Ag-2.0% Ge No peeling 7 Ag-2.0% Cu No peeling 8 Ag-2.0% Ni Peeling 9 Ag-2.0% Au Peeling 10 Ag-2.0% Y Peeling 11 Ag-2.0% Nd No peeling 12 Pure Ag Peeling 13 Ag-2.0% Al Peeling 14 Ag-2.0% Ga Peeling 15 Ag-2.0% In Peeling 16 Ag-2.0% Pd Peeling 17 Ag-2.0% Pt Peeling

In Table 4, in the Ag bicomponent alloy containing the components of Cu, Ti, W, Mo, Sn, Ge, and Nd, no peeling occurred over the entire surface of the substrate, and thus it was found that the adhesion was very excellent.

Example 6

In the present Example, the adhesiveness of various Ag type alloy thin films was evaluated by the peeling test.

First, with respect to the sample recognized as having good adhesion among the samples of Example 5, various Ag bicomponent alloy thin films were prepared in the same manner as in Example 5 except that the size of the resin substrate used was changed to the substrate size of 12.7 x 12.7 mm. The formed sample was prepared. Next, the peel test was performed on the sample and the adhesion was quantitatively evaluated by measuring the load (tensile strength) at the time of peeling. Specifically, a metal jig is attached and fixed to the substrate side and the thin film side of the sample, and a tensile test is performed on both metal jigs by a tensile tester, so that the load (tensile strength) when the thin film and the substrate are peeled off at the interface. Measure On the other hand, an adhesive is usually used for attachment fixing of a metal jig, but in this embodiment, an ordinary temperature curing type two-component epoxy resin was used as an adhesive to avoid the need for heat during adhesion. In addition, the same test was carried out with respect to Ag binary alloy thin films containing other elements for comparison. These results are shown in Table 5.

No. Alloy Tensile strength (kgf / ㎠) One Ag-2.0% Ti 170.3 2 Ag-2.0% W 105.4 3 Ag-2.0% Mo 102.8 4 Ag-2.0% Sn 137.7 5 Ag-2.0% Ge 173.8 6 Ag-2.0% Nd 180.4 7 Ag-2.0% Cu 91.4 8 Pure Ag 19.0 9 Ag-2.0% Al 76.7 10 Ag-2.0% Mg 44.7 11 Ag-2.0% Ga 49.6 12 Ag-2.0% In 25.1

In Table 5, the Ag bicomponent alloys of Nos. 1 to 7, which are considered to have better adhesion than Example 5, exhibit very high adhesion with a tensile strength of 90 kgf / cm 2 or more. On the other hand, as other Ag binary alloys, the tensile strength was low and the adhesiveness was inferior.

As a result of the peeling test, the alloys of Ag-Cu, Ag-Ti, Ag-W, Ag-Mo, Ag-Sn, Ag-Ge, and Ag-Nd are very good in adhesion. The point was confirmed.

Example 7

A sample in which a four-component alloy thin film (reflective thin film layer) of Ag-3.0% Zn-0.85% Sn-1.0% Au having a thickness of 1000 동일 was formed in the same manner as in Example 6 using various Ag four-component alloy targets shown in Table 6. Prepared. Meanwhile, the following three kinds of targets were used for the Ag tetracomponent alloy target.

(1) Ag-3.0% Zn-0.85% Sn-1.0% Au quaternary alloy prepared by vacuum melting method

(2) Ag-3.0% Zn-0.85% Sn-1.0% Au quaternary alloy manufactured by powder metallurgy

(3) Mosaic-like targets adjusted to have a thin film composition of Ag-3.0% Zn-0.85% Sn-1.0% Au alloy (composite targets in which chips of An, Sn, Au are plated on pure Ag targets) )

About the said sample, the reflecting thin film layer was evaluated by measuring the initial reflectance similarly to Example 1, performing a high temperature, high humidity test (temperature 80 degreeC, 90% RH of humidity), and calculating the amount of reflectance fall before and behind a test. The obtained results are shown in Table 6.

Type of sputtering target reflectivity(%) Reflectance change (△%) Measurement wavelength: λ = 800 nm Measurement wavelength: λ = 390 nm Measurement wavelength: λ = 800 nm Measurement wavelength: λ = 390 nm (One) 90.5 71.6 -0.9 -8.4 (2) 88.4 67.5 -2.3 -14.7 (3) 90.1 71.3 -1.1 -8.9

In Table 6, the Ag tetracomponent alloy thin film in which the film | membrane was formed using the various targets of said (1)-(3) was all high in initial reflectance, and the reflectance change amount was small. Especially, since the said target (1) showed the said tendency remarkably, it turns out that the use of the said solvent Ag type alloy sputtering target is the most suitable.

On the other hand, the same experiment as in the present embodiment to the Ag-Zn alloy of at least one of Cu, Ti, Nd, W, Mo, Sn, Ge; Samples added with at least one of Cu, Ni, Au, Y, and Nd were also carried out, and as a result, it was confirmed that the effects shown in Table 6 were obtained.

Example 8

In the present Example, the initial reflectance, corrosion resistance (oxidation resistance), and sulfidation resistance of the three-component alloy thin film which added the 3rd component to Ag-Zn type alloy were investigated.

Specifically, by the same method as in Example 1, various Ag bicomponent alloy thin films shown in Fig. 5 (as the third component, each element of Cu, Y, Ni, Nd, Au is in the range of 0 to 6%. The sample formed by changing and adding) was produced, and the relationship between various alloy thin films and initial reflectance was investigated. 5 shows the relationship between the amount of the third component added and the initial reflectance at the wavelength of 700 nm.

In Fig. 5, in both alloys, the reflectance tends to decrease gradually by the addition of the third component, but even when the third component is added 5%, the high reflectance of 85% or more can be maintained. Thus, it can be seen that the addition of the above element as the third component is useful.

Next, the corrosion resistance (oxidation resistance) of the reflective layer thin film was evaluated by the method similar to Example 1 about the said sample. In FIG. 6, the relationship between the reflectance change amount and the addition amount of a 3rd component in wavelength 700mm before and after a high temperature, high humidity test is shown.

In FIG. 6, it can be seen that the addition of the third component does not change the amount of reflectance reduction or is very small. Therefore, the corrosion resistance (oxidation resistance) is improved by the addition of the third component.

In addition, the sulfidation resistance of the reflective thin film layer was evaluated in the same manner as in Example 3 with respect to the sample. 7 shows the relationship between the amount of reduction in reflectance at a wavelength of 700 mm before and after the hydrogen sulfide atmosphere exposure test and the amount of the third component added.

In FIG. 7, the decrease in the reflectance of the Ag tricomponent alloy gradually decreases with the addition of the third component. Thus, when the tricomponent alloy is used, the corrosion resistance (oxidation resistance) is higher than that of the Ag-3% Zn bicomponent alloy. It can be seen that this is improved. On the other hand, the effect varies depending on the type of element, and when the third component is Au, the sulfidation resistance improving effect is most remarkable, and then the improving effect is recognized in the order of Y, Nd, Ni, and Cu.

Example 9

In this example, the adhesiveness of the Ag tricomponent alloy thin film was evaluated.

Specifically, a sample in which various Ag tricomponent alloy thin films shown in Table 7 were formed in the same manner as in Example 1, and then subjected to the adhesion test by the patterning test in the same manner as in Example 5. Table 7 describes the peeling state of the stripe pattern on the Ag three-component alloy thin film.

No. Alloy Evaluation result (peeled state) One Ag-3.0% Zn-2.0% Ti No peeling 2 Ag-3.0% Zn-2.0% W No peeling 3 Ag-3.0% Zn-2.0% Mo No peeling 4 Ag-3.0% Zn-2.0% Sn No peeling 5 Ag-3.0% Zn-2.0% Ge No peeling 6 Ag-3.0% Zn-2.0% Cu No peeling 7 Ag-3.0% Zn-2.0% Ni Peeling 8 Ag-3.0% Zn-2.0% Au Peeling 9 Ag-3.0% Zn-2.0% Y Peeling 10 Ag-3.0% Zn-2.0% Nd No peeling 11 Pure Ag Peeling 12 Ag-3.0% Zn-2.0% Al Peeling 13 Ag-3.0% Zn-2.0% Ga Peeling 14 Ag-3.0% Zn-2.0% In Peeling 15 Ag-3.0% Zn-2.0% Pd Peeling 16 Ag-3.0% Zn-2.0% Pt Peeling

In Table 7, in the Ag-based alloy thin film to which the elements of Cu, Ti, W, Mo, Sn, and Ge were added, no peeling occurred over the entire surface of the substrate, indicating that the adhesion was very excellent.

Example 10

In the present Example, the adhesiveness of the Ag tricomponent alloy thin film was evaluated by the evaluation method separate from Example 9.

Specifically, in the same manner as in Example 1, samples in which various Ag-Zn-X three-component alloy thin films (X is Ti, W, Mo, Sn. Ge, and Nd) were formed. Then, the peel test was carried out in the same manner as in Example 6 to evaluate the adhesion quantitatively. The result is written together in FIG.

In FIG. 8, it can be seen that the adhesion strength (tensile strength at the time of peeling) of the Ag-based alloy increases with the addition of the third element and the adhesion is improved as compared with the Ag-Zn bicomponent alloy and pure Ag. Adhesion synergy was Ti largest, followed by W, Sn, Nd, Mo, and Ge.

The reflective layer for the optical information recording medium of the present invention not only exhibits high reflectance but also has excellent sulfidation resistance, and also has good adhesion to disk substrates (polycarbonate substrates and the like) and other thin films constituting the disk. The performance or reliability of the recording medium (phase change type and recordable optical disc) can be significantly improved. In addition, the sputtering target of the present invention is suitably used when forming the reflective layer for optical information recording medium by sputtering, and in addition to the advantage that the component composition of the reflective thin film layer formed is easy to be stabilized, various characteristics such as sulfidation resistance, reflectance, adhesion, etc. There is also an advantage that an excellent reflective thin film layer can be obtained efficiently.

Claims (5)

A reflective layer for an optical information recording medium having excellent sulfidation resistance, comprising Ag-based alloy containing 1.5 atomic% or more of Zn. The method of claim 1, A reflective layer for an optical information recording medium having improved adhesion by the Ag-based alloy containing 0.5 to 5 atomic percent of at least one element selected from the group consisting of Cu, Ti, Nd, W, Mo, Sn, and Ge. The method according to claim 1 or 2, A reflection layer for an optical information recording medium, wherein the Ag-based alloy contains 0.5 to 3 atomic% in total of at least one element selected from the group consisting of Cu, Ni, Au, Y, and Nd. An optical information recording medium comprising the reflective layer for an optical information recording medium according to any one of claims 1 to 3. A sputtering target for a reflective layer of an optical information recording medium, characterized by comprising an Ag-based alloy as defined in any one of claims 1 to 3.