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JPH05242525A - Optical recording medium - Google Patents

Optical recording medium

Info

Publication number
JPH05242525A
JPH05242525A JP4041713A JP4171392A JPH05242525A JP H05242525 A JPH05242525 A JP H05242525A JP 4041713 A JP4041713 A JP 4041713A JP 4171392 A JP4171392 A JP 4171392A JP H05242525 A JPH05242525 A JP H05242525A
Authority
JP
Japan
Prior art keywords
optical recording
substrate
layer
dielectric layer
optical
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP4041713A
Other languages
Japanese (ja)
Inventor
Akihiro Maesaka
明弘 前坂
Shunichi Hashimoto
俊一 橋本
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sony Corp
Original Assignee
Sony Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sony Corp filed Critical Sony Corp
Priority to JP4041713A priority Critical patent/JPH05242525A/en
Publication of JPH05242525A publication Critical patent/JPH05242525A/en
Pending legal-status Critical Current

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Abstract

PURPOSE:To prevent the thermal damage of a substrate and to enable the repetitive execution of good reproducing by providing dielectric layers having the thermal conductivity on the substrate side higher than the thermal conductivity on the optical recording layer side between the substrate and the optical recording layer. CONSTITUTION:This optical recording medium has the dielectric layers 1 constituted of two layers. The thermal conductivity of the first dielectric layer 3 on the substrate 2 side is higher than the thermal conductivity of the second dielectric layer 5 on the optical recording layer 4 side. The optical recording layer is effectively heated up and the heat conduction from the optical recording layer to the substrate is suppressed when such dielectric layers are provided. Then, the thermal damage of the substrate is prevented at the time of recording even in the case the optical recording medium has the optical recording layer for which high-temp. thermal recording is required. The good signal recording is thus executed.

Description

【発明の詳細な説明】Detailed Description of the Invention

【0001】[0001]

【産業上の利用分野】本発明は、レーザ光の照射により
情報の記録・再生を行う光記録媒体に関する。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium for recording / reproducing information by irradiating a laser beam.

【0002】[0002]

【従来の技術】従来、レーザ光の照射により情報の記録
・再生を行う光記録媒体としては、光磁気ディスク,各
種追記型光ディスク,デジタルオーディオディスク(い
わゆるコンパクトディスク),光学式ビデオディスク
(いわゆるレーザーディスク)等の各種媒体が実用化さ
れており、このうち、特に光磁気ディスクは、ユーザに
よる繰り返し記録再生が可能なことから注目されてい
る。
2. Description of the Related Art Conventionally, as an optical recording medium for recording / reproducing information by irradiating a laser beam, a magneto-optical disc, various write-once optical discs, digital audio discs (so-called compact discs), optical video discs (so-called lasers). Various media such as a disk have been put into practical use, and among them, a magneto-optical disk has been particularly noted because it can be repeatedly recorded and reproduced by a user.

【0003】上記光磁気ディスクでは、膜面と垂直方向
に磁化容易軸を有し且つ磁気光学効果の大きな磁性薄膜
を記録磁性層として使用する。そして、情報の記録に際
しては、この磁性薄膜にレーザー光を照射して該磁性薄
膜を部分的にキュリーまたは温度補償点を越えて昇温
し、この部分の保磁力を消滅させて外部から印加される
記録磁界の方向に磁化の向きを反転させる。一方、記録
された情報を再生するには、磁性薄膜にレーザ光を照射
して、磁気光学効果による反射光あるいは透過光の偏光
面の回転を検出する。また、上記光磁気ディスクは、通
常、上記記録磁性層とともに耐蝕性の向上や多重反射に
よるカー回転角の増大を目的としてSi34 等よりな
る誘電体層が設けられる。すなわち、具体的には、基板
上に誘電体層、記録磁性層、保護層等が順次積層された
構成とされ、基板側からレーザ光を照射することによっ
て記録再生が行われる。
In the above magneto-optical disk, a magnetic thin film having an easy axis of magnetization in the direction perpendicular to the film surface and having a large magneto-optical effect is used as a recording magnetic layer. When recording information, the magnetic thin film is irradiated with a laser beam to partially raise the temperature of the magnetic thin film beyond the Curie or temperature compensation point, and the coercive force of this part is extinguished and applied from the outside. The direction of the magnetization is reversed in the direction of the recording magnetic field. On the other hand, in order to reproduce the recorded information, the magnetic thin film is irradiated with laser light to detect rotation of the plane of polarization of reflected light or transmitted light due to the magneto-optical effect. Further, the magneto-optical disk is usually provided with a dielectric layer made of Si 3 N 4 or the like together with the recording magnetic layer for the purpose of improving corrosion resistance and increasing Kerr rotation angle due to multiple reflection. That is, specifically, a dielectric layer, a recording magnetic layer, a protective layer, and the like are sequentially stacked on a substrate, and recording / reproducing is performed by irradiating a laser beam from the substrate side.

【0004】ところで、上記光磁気ディスクにおいて記
録磁性層に使用される材料としては、従来よりGd,T
b,Dy等の希土類元素とFe,Co等の遷移元素とを
組み合わせた非晶質合金膜が代表的なものとされてい
る。この非晶質合金膜において、特に希土類元素として
Tbを含むTbFeCo膜やGdTbFe膜等は大きな
垂直磁気異方性を示し、既に実用化されている。
By the way, as a material used for the recording magnetic layer in the above-mentioned magneto-optical disk, Gd and T have been conventionally used.
A typical amorphous alloy film is a combination of rare earth elements such as b and Dy and transition elements such as Fe and Co. In this amorphous alloy film, a TbFeCo film, a GdTbFe film and the like containing Tb as a rare earth element exhibit a large perpendicular magnetic anisotropy and have already been put to practical use.

【0005】しかし、上記非晶質合金膜の構成成分であ
る希土類元素やFeは非常に酸化され易く、空気中の酸
素とも容易に結合して酸化物を形成する性質がある。こ
のため、このような酸化の進行により腐食や孔食が発生
し、記録信号の脱落を誘起する虞れがある。また、特に
希土類元素が選択的に酸化を受けると、保磁力や残留磁
気カー回転角の低下に伴ってC/N比が劣化するという
問題が生ずる。このような問題は、希土類元素を使用す
る限り免れることはできない。
However, the rare earth elements and Fe, which are the constituents of the amorphous alloy film, are very easily oxidized and have the property of easily combining with oxygen in the air to form an oxide. For this reason, there is a possibility that corrosion or pitting corrosion may occur due to the progress of such oxidation, which may cause loss of the recording signal. Further, particularly when the rare earth element is selectively oxidized, there arises a problem that the C / N ratio is deteriorated as the coercive force and the residual magnetic Kerr rotation angle are decreased. Such problems cannot be escaped as long as rare earth elements are used.

【0006】そこで、希土類元素の代わりにPtやPd
等の貴金属を使用したCo−Pt系材料、或いはCo−
Pd系材料が記録磁性層として検討されている。たとえ
ばCo層とPt層とを交互に積層したCo−Pt系多層
金属薄膜は、良好な耐食性を有し、かつ全厚の薄い領域
で優れた磁気光学特性を有することが知られている。
Therefore, Pt or Pd is used instead of the rare earth element.
-Pt-based materials using precious metals such as
Pd-based materials have been studied for recording magnetic layers. For example, it is known that a Co-Pt-based multi-layer metal thin film in which Co layers and Pt layers are alternately laminated has good corrosion resistance and excellent magneto-optical characteristics in a region where the total thickness is thin.

【0007】[0007]

【発明が解決しようとする課題】ところで、上記Co−
Pt系多層金属薄膜は、キュリー温度が250〜300
℃とTbFeCo膜と比べて100℃程度高い。このた
め、Co−Pt系多層金属薄膜を記録磁性層とする光磁
気ディスクでは、記録に際して磁性薄膜を250〜30
0℃とかなり高い温度にまで温度上昇させる必要がある
By the way, the above-mentioned Co-
The Pt-based multilayer metal thin film has a Curie temperature of 250 to 300.
C. and about 100.degree. C. higher than that of the TbFeCo film. Therefore, in a magneto-optical disk using a Co-Pt-based multi-layered metal thin film as a recording magnetic layer, the magnetic thin film is recorded in an amount of 250 to 30
It is necessary to raise the temperature to a temperature as high as 0 ° C

【0008】ところが、従来の構成の光磁気ディスクで
は、磁性薄膜が250〜300℃以上にまで温度上昇す
ると、それに伴って基板温度も200〜280℃にまで
上昇する。通常、この種の光磁気ディスクでは、基板と
してポリカーボネート基板が使用されているが、このポ
リカーボネート基板の軟化温度は150℃程度であるた
め、上述のように温度上昇した場合には、基板が熱損傷
し、たとえば、情報記録後、記録消去処理を行っても未
消去信号が検出されるといった不都合が生じてしまう。
However, in the conventional magneto-optical disk, when the temperature of the magnetic thin film rises to 250 to 300 ° C. or higher, the substrate temperature rises to 200 to 280 ° C. accordingly. Usually, in this type of magneto-optical disk, a polycarbonate substrate is used as a substrate. However, since the softening temperature of this polycarbonate substrate is about 150 ° C., when the temperature rises as described above, the substrate is thermally damaged. However, for example, even if the recording / erasing process is performed after the information is recorded, an unerased signal may be detected.

【0009】そこで、本発明はこのような従来の実情に
鑑みて提案されたものであり、光記録層に対して高温熱
記録を行った場合でも基板に熱損傷が生じない光記録媒
体を提供することを目的とする。
Therefore, the present invention has been proposed in view of such a conventional situation, and provides an optical recording medium in which thermal damage does not occur on a substrate even when high-temperature thermal recording is performed on the optical recording layer. The purpose is to do.

【0010】[0010]

【課題を解決するための手段】上述の目的を達成するた
めに、本発明の光記録媒体は、基板、誘電体層、光記録
層を順次積層してなる光記録媒体において、前記誘電体
層の基板側の熱伝導率が光記録層側の熱伝導率よりも大
きいことを特徴とするものである。
In order to achieve the above object, an optical recording medium of the present invention is an optical recording medium comprising a substrate, a dielectric layer and an optical recording layer which are sequentially laminated. The heat conductivity of the substrate side is higher than that of the optical recording layer side.

【0011】本発明は、特に、熱量印加によって情報記
録が行われる光記録層を有してなる光記録媒体に適用さ
れる。熱量印加により記録が行われる光記録層として
は、光磁気記録媒体において形成されるTbFeCo非
晶質系薄膜等の希土類−遷移金属非晶質合金膜、Co層
とPt層とを交互に積層してなるCo−Pt系多層金属
薄膜、あるいは追記型光記録媒体において形成される低
融点金属薄膜,相変化膜,有機色素を含有する膜等が挙
げられる。
The present invention is particularly applicable to an optical recording medium having an optical recording layer on which information is recorded by applying heat. The optical recording layer on which recording is performed by application of heat is a rare earth-transition metal amorphous alloy film such as a TbFeCo amorphous thin film formed in a magneto-optical recording medium, and Co layers and Pt layers are alternately laminated. And a low melting point metal thin film formed in a write-once type optical recording medium, a phase change film, a film containing an organic dye, and the like.

【0012】これら、光記録層を有する光記録媒体に対
して安定な情報記録を行うには、光記録層を所定温度に
まで上昇させるに足る熱量を印加する必要がある。特
に、Co−Pt系多層金属薄膜を記録層とする光磁気記
録媒体では、光記録層を250℃〜300℃にまで温度
上昇させることによって良好な情報記録が得られる。と
ころが、光記録層で発生した熱は誘電体層を通して基板
に伝導し、基板の温度を上昇させる。このとき基板の温
度がその軟化点を越えた場合には、基板が熱損傷し、光
記録媒体の特性が劣化する。
In order to perform stable information recording on these optical recording media having an optical recording layer, it is necessary to apply a sufficient amount of heat to raise the optical recording layer to a predetermined temperature. Particularly, in a magneto-optical recording medium having a Co-Pt-based multilayer metal thin film as a recording layer, good information recording can be obtained by raising the temperature of the optical recording layer to 250 ° C to 300 ° C. However, the heat generated in the optical recording layer is conducted to the substrate through the dielectric layer and raises the temperature of the substrate. At this time, if the temperature of the substrate exceeds its softening point, the substrate is thermally damaged and the characteristics of the optical recording medium are deteriorated.

【0013】そこで、本発明においては、このような基
板の温度上昇を抑えるために、基板と記録層の間に基板
側の熱伝導率が記録層側の熱伝導率よりも大きい誘電体
層を設ける。このような誘電体層を設けると、光記録層
が効果的に温度上昇するとともに光記録層から基板への
熱伝導が抑えられる。したがって、高温熱記録が必要な
光記録層を有する場合でも、記録に際して基板を熱損傷
させることなく、良好な信号記録がなされるようにな
る。
Therefore, in the present invention, in order to suppress such a temperature rise of the substrate, a dielectric layer having a thermal conductivity on the substrate side higher than that on the recording layer side is provided between the substrate and the recording layer. Set up. Providing such a dielectric layer effectively raises the temperature of the optical recording layer and suppresses heat conduction from the optical recording layer to the substrate. Therefore, even if an optical recording layer that requires high temperature thermal recording is provided, good signal recording can be performed without causing thermal damage to the substrate during recording.

【0014】上記誘電体層としては、熱伝導率が膜厚方
向に連続的に変化するもの、あるいは熱伝導率の異なる
複数の誘電体膜を、基板側の誘電体膜の熱電率が光記録
層側の誘電体膜の熱伝導率よりも常に大きくなるように
積層した多層構成のものがあるが、形成の容易さの点か
ら後者の多層構成の誘電体層の方が実用的である。
As the above-mentioned dielectric layer, one whose thermal conductivity continuously changes in the film thickness direction, or a plurality of dielectric films having different thermal conductivities, in which the thermoelectric constant of the dielectric film on the substrate side is optically recorded Although there is a multi-layered structure in which layers are laminated so that the thermal conductivity of the dielectric film on the layer side is always higher, the latter dielectric layer having a multi-layered structure is more practical from the viewpoint of ease of formation.

【0015】誘電体層を多層構成とする場合、各誘電体
層の層厚dn はカー効果エンハンスメントを得る点から
0Å<dn <3000Åとすることが望ましい。また、
各誘電体層の層厚比によって光記録媒体の感度が変化す
るので、各誘電体層の層厚比は、所望の感度に併せてを
調整することが望ましい。また、誘電体層の光学干渉層
厚D(=Σdn )は、0Å<D<5000Åとすること
が好ましい。光学干渉層厚Dをこの範囲とすることによ
り、カー回転角と反射率の積が大きくなり、高感度化が
達成される。
When the dielectric layers have a multi-layered structure, the layer thickness d n of each dielectric layer is preferably 0Å <d n <3000Å from the viewpoint of obtaining Kerr effect enhancement. Also,
Since the sensitivity of the optical recording medium changes depending on the layer thickness ratio of each dielectric layer, it is desirable to adjust the layer thickness ratio of each dielectric layer in accordance with the desired sensitivity. Further, the optical interference layer thickness D (= Σd n ) of the dielectric layer is preferably 0Å <D <5000Å. By setting the optical interference layer thickness D in this range, the product of the Kerr rotation angle and the reflectance is increased, and high sensitivity is achieved.

【0016】上記誘電体層としては、酸化物や窒化物等
が使用可能であり、誘電体層の熱伝導率は、組成,膜の
形態,成膜方法等をコントロールすることにより所望の
値とすることができる。
As the above-mentioned dielectric layer, an oxide, a nitride or the like can be used, and the thermal conductivity of the dielectric layer can be set to a desired value by controlling the composition, film form, film forming method and the like. can do.

【0017】なお、上記誘電体層、記録層が形成される
基板としては、アクリル樹脂基板,ポリカーボネート樹
脂基板,ポリオレフィン樹脂基板,エポキシ樹脂基板
等,通常、この種の光記録媒体に使用されている基板が
いずれも使用可能である。
As the substrate on which the dielectric layer and the recording layer are formed, an acrylic resin substrate, a polycarbonate resin substrate, a polyolefin resin substrate, an epoxy resin substrate, etc. are usually used for this kind of optical recording medium. Any substrate can be used.

【0018】また、本発明の光記録媒体は、上記光記録
層上にさらに誘電体層,反射層等を形成するようにして
もよい。ただし、光記録層上に形成する上記誘電体層に
ついては、熱伝導率を規制しても特に効果はないので、
誘電体層として通常の組成,膜形態の酸化物、窒化物を
使用すればよい。
Further, in the optical recording medium of the present invention, a dielectric layer, a reflective layer and the like may be further formed on the above optical recording layer. However, for the above-mentioned dielectric layer formed on the optical recording layer, there is no particular effect even if the thermal conductivity is regulated,
As the dielectric layer, an oxide or nitride having a normal composition and film form may be used.

【0019】また、反射層は、熱的に良導体であること
が好ましく、入手の容易さ成膜の容易さ等を考慮すると
アルミニウムが適している。
The reflective layer is preferably a good conductor in terms of heat, and aluminum is suitable in view of availability and film formation.

【0020】[0020]

【作用】光記録媒体において、基板と光記録層の間に基
板側の熱伝導率が光記録層側の熱伝導率よりも大なる誘
電体層を設けると、レーザ光を照射したときに光記録層
が効果的に温度上昇し、しかも光記録層で発生した熱の
基板への伝導が抑えられる。したがって、高温熱記録が
必要な光記録層を有する場合でも、記録に際して基板に
熱損傷を生じさせることなく、良好な信号記録がなされ
る。
In the optical recording medium, if a dielectric layer having a thermal conductivity on the substrate side higher than the thermal conductivity on the optical recording layer side is provided between the substrate and the optical recording layer, the optical layer emits light when irradiated with laser light. The temperature of the recording layer is effectively increased, and the heat generated in the optical recording layer is suppressed from being conducted to the substrate. Therefore, even if an optical recording layer that requires high temperature thermal recording is provided, good signal recording can be performed without causing thermal damage to the substrate during recording.

【0021】[0021]

【実施例】本発明の好適な実施例について実験結果に基
づいて説明する。実施例1 本実施例は、図1に示すように2層構成の誘電体層1を
有し、基板2側の第1の誘電体層3の熱伝導率が光記録
層4側の第2の誘電体層5の熱伝導率よりも大とされた
光ディスクの例である。
EXAMPLES Preferred examples of the present invention will be described based on experimental results. Example 1 This example has a two-layered dielectric layer 1 as shown in FIG. 1, and the thermal conductivity of the first dielectric layer 3 on the substrate 2 side is the second on the optical recording layer 4 side. This is an example of an optical disc having a thermal conductivity higher than that of the dielectric layer 5.

【0022】<光ディスクの温度分布の検討>ポリカー
ボネート(PC)基板上に、第1の誘電体層として表1
に示す膜を、第2の誘電体層としてSiO2 膜を成膜し
て誘電体層を形成し、さらにこの誘電体層上に光記録層
としてCo−Pt多層金属薄膜を順次成膜して光ディス
ク(ディスク1,ディスク2,ディスク3)を作製し
た。
<Study of temperature distribution of optical disk> As a first dielectric layer on a polycarbonate (PC) substrate, Table 1
SiO 2 film is formed as a second dielectric layer to form a dielectric layer, and a Co—Pt multilayer metal thin film is sequentially formed on the dielectric layer as an optical recording layer. Optical disks (disk 1, disk 2, disk 3) were produced.

【0023】[0023]

【表1】 [Table 1]

【0024】なお、誘電体層は高周波反応性スパッタリ
ングによって成膜し、第1の誘電体層および第2の誘電
体層の膜厚はともに500Åである。また、Co−Pt
多層金属薄膜は、直流マグネトロンスパッタリングによ
ってガス圧4×10-3TorrのXeガス雰囲気中で成
膜した。Co−Pt多層金属薄膜の膜厚構成は、Co層
が4Å,Pt層が13Å,全膜厚が200Åである。
The dielectric layer is formed by high frequency reactive sputtering, and the film thickness of both the first dielectric layer and the second dielectric layer is 500Å. In addition, Co-Pt
The multilayer metal thin film was formed by DC magnetron sputtering in a Xe gas atmosphere with a gas pressure of 4 × 10 −3 Torr. The thickness of the Co-Pt multilayer metal thin film is 4 Å for the Co layer, 13 Å for the Pt layer, and 200 Å for the total film thickness.

【0025】このようにして作製された各光ディスクに
ついて、レーザ光をカットオフした直後の膜厚方向にお
ける温度分布を熱シミュレーションにより調べた。図2
にその結果を示す。なお、熱シミュレーションは、数1
の3次元熱伝導方程式を用いて行った。また、シミュレ
ーション条件は、線速1.4m/秒、記録パワー5m
W、マーク長1μmである。誘電体層,ポリカーボネー
ト基板,Co−Pt多層金属薄膜の比熱,密度,熱伝導
率は表2に示す通りである。
With respect to each of the optical discs thus manufactured, the temperature distribution in the film thickness direction immediately after the laser light was cut off was examined by thermal simulation. Figure 2
The results are shown in. The thermal simulation is
The three-dimensional heat conduction equation of The simulation conditions are a linear velocity of 1.4 m / sec and a recording power of 5 m.
W, mark length 1 μm. Table 2 shows specific heat, density and thermal conductivity of the dielectric layer, the polycarbonate substrate and the Co-Pt multilayer metal thin film.

【0026】[0026]

【数1】 [Equation 1]

【0027】[0027]

【表2】 [Table 2]

【0028】図2からわかるように、ディスク1〜ディ
スク3においては、光記録層と基板間の温度差は150
〜200℃であり、基板と光記録層の間に大きな温度勾
配が生じる。このことは、キュリー温度が250〜30
0℃のCo−Pt多層金属薄膜に対して最適記録パワー
で熱磁気記録を行った場合にも基板温度はその軟化点で
ある150℃を越えず、基板に熱損傷が生じないことを
意味している。したがって、基板と光記録層の間に基板
側の熱伝導率が光記録層側の熱伝導率よりも大とされた
誘電体層を設けることは、基板の熱損傷を防止する上で
有効であることがわかった。
As can be seen from FIG. 2, in the discs 1 to 3, the temperature difference between the optical recording layer and the substrate is 150.
Is about 200 ° C., and a large temperature gradient is generated between the substrate and the optical recording layer. This means that the Curie temperature is 250-30.
Even when thermomagnetic recording is performed on the Co—Pt multilayer metal thin film at 0 ° C. with the optimum recording power, the substrate temperature does not exceed the softening point of 150 ° C., which means that the substrate is not damaged by heat. ing. Therefore, it is effective to prevent thermal damage to the substrate by providing a dielectric layer between the substrate and the optical recording layer whose thermal conductivity on the substrate side is higher than that on the optical recording layer side. I knew it was.

【0029】また、ディスク1〜ディスク3を比較する
と、基板と光記録層の間の温度勾配は、第1の誘電体層
と第2の誘電体層の熱伝導率の比が大きくなるのに伴っ
て増大している。このことから、上記誘電体層を有する
光ディスクでは、誘電体層の熱伝導率を制御することに
より、温度勾配を調整することが可能であることがわか
った。
Comparing disks 1 to 3, the temperature gradient between the substrate and the optical recording layer is such that the ratio of the thermal conductivity of the first dielectric layer and the second dielectric layer becomes large. It is increasing with it. From this, it was found that in the optical disc having the above-mentioned dielectric layer, the temperature gradient can be adjusted by controlling the thermal conductivity of the dielectric layer.

【0030】次に、誘電体層の膜厚構成と光ディスクの
温度分布の関係について調べた。第1の誘電体層として
AlN膜を、第2の誘電体層としてSiO2 膜を成膜
し、誘電体層の全体の膜厚が1000Åとなるように、
第1の誘電体層を200Å,500Å,800Å、第2
の誘電体層の膜厚を800Å,500Å,200Åと変
化させる以外は上述の場合と同様にして光ディスクを作
製した。
Next, the relationship between the film thickness constitution of the dielectric layer and the temperature distribution of the optical disk was examined. An AlN film is formed as the first dielectric layer and a SiO 2 film is formed as the second dielectric layer so that the total thickness of the dielectric layer is 1000 Å.
The first dielectric layer is 200Å, 500Å, 800Å, the second
An optical disk was produced in the same manner as above except that the thickness of the dielectric layer was changed to 800Å, 500Å, 200Å.

【0031】そして、作製された光ディスクについて上
述の場合と同様にして、膜厚方向における温度分布を熱
シミュレーションによって調べた。その結果を図3に示
す。
Then, the temperature distribution in the film thickness direction of the produced optical disk was examined by thermal simulation in the same manner as described above. The result is shown in FIG.

【0032】図3からわかるように、上記光ディスクの
温度分布曲線は、第1の誘電体層と第2の誘電体層の層
厚比を変えることによって平行移動する。このことか
ら、上記光ディスクにおいては、第1の誘電体層と第2
の誘電体層の層厚比を選択することによって、温度勾配
をほとんど変えずに、所望の熱感度を持たせることが可
能であることがわかった。
As can be seen from FIG. 3, the temperature distribution curve of the optical disk is translated by changing the layer thickness ratio of the first dielectric layer and the second dielectric layer. Therefore, in the above optical disc, the first dielectric layer and the second dielectric layer
It was found that by selecting the layer thickness ratio of the dielectric layer, it is possible to provide desired thermal sensitivity with almost no change in temperature gradient.

【0033】<光ディスクの記録再生特性の検討>上述
の結果から、Co−Pt多層金属薄膜を光記録層とする
光ディスクにおいて、温度勾配,感度が最適となる誘電
体層の構成は、第1の誘電体層がAlN膜、第2の誘電
体層がSiO2 膜であり、AlN膜の膜厚が700Å,
SiO2 膜の膜厚が300Åであることが推測された。
<Study of Recording / Reproducing Characteristics of Optical Disc> From the above results, in the optical disc using the Co—Pt multi-layer metal thin film as the optical recording layer, the first dielectric layer composition has the optimum temperature gradient and sensitivity. The dielectric layer is an AlN film, the second dielectric layer is a SiO 2 film, and the film thickness of the AlN film is 700Å,
It was estimated that the film thickness of the SiO 2 film was 300Å.

【0034】そこで、次に、上記構成の誘電体層を有す
る光磁気記録媒体について実際に記録消去を行い再生信
号を検討した。
Therefore, next, the reproduction signal was examined by actually erasing the recording on the magneto-optical recording medium having the dielectric layer having the above structure.

【0035】まず、第1の誘電体層として膜厚700Å
のAlN膜を、第2の誘電体層として膜厚300ÅのS
iO2 膜を成膜する以外は上述の場合と同様にして光デ
ィスクを作製した。このようにして作製された光ディス
クについて、780nm波長のレーザ光源を用いた評価
装置によって信号記録後、および記録信号消去後の再生
信号のCN比を調べた。その結果を図4に示す。
First, as the first dielectric layer, the film thickness is 700Å
AlN film as the second dielectric layer is used as an S film having a film thickness of 300Å
An optical disk was produced in the same manner as above except that the iO 2 film was formed. With respect to the optical disc manufactured in this manner, the CN ratio of the reproduced signal after signal recording and after recording signal erasing was examined by an evaluation device using a laser light source of 780 nm wavelength. The result is shown in FIG.

【0036】なお、評価条件は、ディスク回転数600
rpm,線速3m/秒,記録周波数1.5MHz,記録
磁界200Oe,再生パワー1mWである。また、消去
処理は、上記光磁気ディスクの保磁力(1kOe)を考
慮して、光磁気ディスクにこの保磁力よりも十分大きい
10kOeの磁界を一方向から印加することによって行
った。
The evaluation condition is that the disk rotation speed is 600.
rpm, linear velocity 3 m / sec, recording frequency 1.5 MHz, recording magnetic field 200 Oe, reproduction power 1 mW. The erasing process was performed by applying a magnetic field of 10 kOe, which is sufficiently larger than this coercive force, to the magneto-optical disk from one direction in consideration of the coercive force (1 kOe) of the magneto-optical disk.

【0037】図4からわかるように、上記光ディスクに
おいては、記録パワーが3〜9mWで一定のC/N比が
えられる。したがって、信号記録には少なくとも3mW
以上の記録パワーが必要である。一方、記録信号消去後
のCN比を見ると、記録パワーを3mW以上とした場合
にも、未消去信号は出現しない。また、基板を観察した
ところ、熱損傷は確認されなかった。
As can be seen from FIG. 4, in the above optical disc, a constant C / N ratio can be obtained at a recording power of 3 to 9 mW. Therefore, at least 3 mW for signal recording
The above recording power is required. On the other hand, looking at the CN ratio after erasing the recorded signal, no unerased signal appears even when the recording power is set to 3 mW or more. Moreover, when the substrate was observed, no thermal damage was confirmed.

【0038】したがって、これらの結果から、基板と光
記録層の間に基板側の熱伝導率が光記録層側の熱伝導率
よりも大とされた誘電体層が設けられた光ディスクは、
記録パワーを高くした場合にも未消去信号が残存するこ
とがなく良好な記録再生を繰り返し行うことが可能であ
ることがわかった。
Therefore, from these results, the optical disk provided with the dielectric layer having the thermal conductivity on the substrate side higher than that on the optical recording layer side is provided between the substrate and the optical recording layer.
It was found that good recording and reproduction can be repeatedly performed without leaving unerased signals even when the recording power is increased.

【0039】比較例1 図5に示すように、光記録層21と基板22の間に熱伝
導率が膜厚方向に均一な誘電体層23が介在されてなる
光記録媒体の例である。
Comparative Example 1 As shown in FIG. 5, this is an example of an optical recording medium in which a dielectric layer 23 having a uniform thermal conductivity in the film thickness direction is interposed between an optical recording layer 21 and a substrate 22.

【0040】ポリカーボネート基板上に、誘電体層とし
てSi3 4 膜、光記録層としてCo−Pt多層金属薄
膜を成膜して2層構造の光ディスクを作製した。なお、
Si3 4 膜は、高周波反応性スパッタリングによって
ガス圧2×10 -3TorrのXeガスとN2 ガスを1:
1で混合した混合ガス雰囲気中、Siターゲットを用い
て成膜した。また、Si3 4 膜の膜厚は、1000Å
(光学シミュレーションにより780nm波長用に最適
化した値)である。
As a dielectric layer on a polycarbonate substrate
Si3NFourCo-Pt multi-layer metal thin film as film and optical recording layer
A film was formed into a two-layer structure optical disc. In addition,
Si3NFourThe film is produced by high frequency reactive sputtering
Gas pressure 2 × 10 -3Torr Xe gas and N2Gas 1:
Using a Si target in the mixed gas atmosphere mixed in 1.
Was deposited. Also, Si3NFourThe film thickness is 1000Å
(Optimal for 780nm wavelength by optical simulation
Value).

【0041】Co−Pt多層金属薄膜は、直流マグネト
ロンスパッタリングによってガス圧4×10-3Torr
のXeガス雰囲気中で成膜した。Co−Pt多層金属薄
膜の膜厚構成は、Co層が4Å、Pt層が13Å、全膜
厚が200Åである。このようにして作製された光ディ
スクについて、実施例1と同様にして膜厚方向における
温度分布を熱シミュレーションによって調べた。その結
果を図6に示す。
The Co-Pt multilayer metal thin film was formed by DC magnetron sputtering at a gas pressure of 4 × 10 -3 Torr.
The film was formed in a Xe gas atmosphere. The thickness of the Co-Pt multilayer metal thin film is 4 Å for the Co layer, 13 Å for the Pt layer, and 200 Å for the total film thickness. With respect to the optical disc manufactured in this manner, the temperature distribution in the film thickness direction was examined by thermal simulation in the same manner as in Example 1. The result is shown in FIG.

【0042】図6を見ると、上記光磁気ディスクにおい
ては、光記録層と基板との温度差は約20℃である。し
たがって、キュリー温度が250〜300℃のCo−P
t層に対して最適パワーで熱磁気記録を行った場合に
は、PC基板の温度はPC基板の軟化温度(〜150
℃)を越えて220℃以上に達し、基板が熱損傷を来す
ものと推測される。
Referring to FIG. 6, in the magneto-optical disk, the temperature difference between the optical recording layer and the substrate is about 20 ° C. Therefore, Co-P with a Curie temperature of 250 to 300 ° C.
When thermomagnetic recording is performed on the t layer with the optimum power, the temperature of the PC substrate is the softening temperature of the PC substrate (up to 150).
It is presumed that the temperature of the substrate exceeds 220 ° C. and the substrate is thermally damaged.

【0043】次に、上記光ディスクについて、実施例1
と同様にして記録再生特性および未消去信号の出現を調
べた。その結果を図7に示す。
Next, regarding the above-mentioned optical disk, Example 1
The recording / reproducing characteristics and appearance of unerased signals were examined in the same manner as in. The result is shown in FIG. 7.

【0044】図7からわかるように、記録パワーのしき
い値は3mWであり、記録パワーを4mW以上にするこ
とにより再生信号のC/Nが飽和する。したがって、上
記光ディスクでは、記録パワーは少なくとも3mW以上
必要である。一方、3mW以上の記録パワーで記録を行
った場合、この光ディスクでは、未消去信号(消し残
り)が出現する。このことから、上記光ディスクは、良
好な繰り返し記録再生が不可能であることがわかった。
As can be seen from FIG. 7, the threshold value of the recording power is 3 mW, and the C / N of the reproduced signal is saturated by setting the recording power to 4 mW or more. Therefore, the above optical disc requires a recording power of at least 3 mW. On the other hand, when recording is performed with a recording power of 3 mW or more, an unerased signal (unerased portion) appears on this optical disc. From this, it was found that good repeat recording / reproduction was impossible on the optical disc.

【0045】[0045]

【発明の効果】以上の説明からも明らかなように、本発
明の光記録媒体は、基板と光記録層の間に基板側の熱伝
導率が光記録層側の熱伝導率よりも大なる誘電体層を設
けるので、光記録層に高温熱記録を行っても、基板が熱
損傷せず、繰り返し良好な記録再生を行うことが可能で
ある。
As is apparent from the above description, in the optical recording medium of the present invention, the thermal conductivity between the substrate and the optical recording layer is higher on the substrate side than on the optical recording layer side. Since the dielectric layer is provided, even if high-temperature thermal recording is performed on the optical recording layer, the substrate is not thermally damaged, and good recording / reproducing can be repeatedly performed.

【0046】したがって、本発明によれば、たとえばC
o−Pt多層金属薄膜等の記録に際して高温とすること
が必要な光記録層を有する光記録媒体の実用性を向上さ
せることが可能となる。
Therefore, according to the present invention, for example, C
It is possible to improve the practicability of an optical recording medium having an optical recording layer that needs to be heated to a high temperature when recording an o-Pt multilayer metal thin film or the like.

【図面の簡単な説明】[Brief description of drawings]

【図1】本発明の光記録媒体の一構成例を示す断面図で
ある。
FIG. 1 is a cross-sectional view showing one structural example of an optical recording medium of the present invention.

【図2】光記録媒体の膜厚方向における温度分布を示す
特性図である。
FIG. 2 is a characteristic diagram showing a temperature distribution in a film thickness direction of an optical recording medium.

【図3】誘電体層の膜厚構成を変化させた場合の光記録
媒体の温度分布を示す特性図である。
FIG. 3 is a characteristic diagram showing the temperature distribution of the optical recording medium when the film thickness configuration of the dielectric layer is changed.

【図4】光記録媒体の記録パワーとC/N比の関係を示
す特性図である。
FIG. 4 is a characteristic diagram showing the relationship between the recording power of an optical recording medium and the C / N ratio.

【図5】従来の光記録媒体の構成を示す断面図である。FIG. 5 is a cross-sectional view showing the structure of a conventional optical recording medium.

【図6】従来の光記録媒体の膜厚方向における温度分布
を示す特性図である。
FIG. 6 is a characteristic diagram showing a temperature distribution in a film thickness direction of a conventional optical recording medium.

【図7】従来の光記録媒体の記録パワーとC/N比の関
係を示す特性図である。
FIG. 7 is a characteristic diagram showing the relationship between the recording power and the C / N ratio of a conventional optical recording medium.

【符号の説明】 1・・・誘電体層 2・・・基板 3・・・第1の誘電体層 4・・・光記録層 5・・・第2の誘電体層[Explanation of Codes] 1 ... Dielectric layer 2 ... Substrate 3 ... First dielectric layer 4 ... Optical recording layer 5 ... Second dielectric layer

Claims (1)

【特許請求の範囲】[Claims] 【請求項1】 基板、誘電体層、光記録層を順次積層し
てなる光記録媒体において、 前記誘電体層の基板側の熱伝導率が光記録層側の熱伝導
率よりも大きいことを特徴とする光記録媒体。
1. An optical recording medium in which a substrate, a dielectric layer, and an optical recording layer are sequentially stacked, wherein the substrate has a thermal conductivity higher than that of the optical recording layer. Characteristic optical recording medium.
JP4041713A 1992-02-27 1992-02-27 Optical recording medium Pending JPH05242525A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP4041713A JPH05242525A (en) 1992-02-27 1992-02-27 Optical recording medium

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP4041713A JPH05242525A (en) 1992-02-27 1992-02-27 Optical recording medium

Publications (1)

Publication Number Publication Date
JPH05242525A true JPH05242525A (en) 1993-09-21

Family

ID=12616068

Family Applications (1)

Application Number Title Priority Date Filing Date
JP4041713A Pending JPH05242525A (en) 1992-02-27 1992-02-27 Optical recording medium

Country Status (1)

Country Link
JP (1) JPH05242525A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003098619A1 (en) * 2002-04-22 2003-11-27 Tdk Corporation Optical recording medium
US7169533B2 (en) * 2001-03-19 2007-01-30 Matsushita Electric Industrial Co., Ltd. Optical information recording medium, method for manufacturing the same and recording/reproduction method

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7169533B2 (en) * 2001-03-19 2007-01-30 Matsushita Electric Industrial Co., Ltd. Optical information recording medium, method for manufacturing the same and recording/reproduction method
WO2003098619A1 (en) * 2002-04-22 2003-11-27 Tdk Corporation Optical recording medium

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