JPH0675306B2 - Magneto-optical recording medium - Google Patents
Magneto-optical recording mediumInfo
- Publication number
- JPH0675306B2 JPH0675306B2 JP5368085A JP5368085A JPH0675306B2 JP H0675306 B2 JPH0675306 B2 JP H0675306B2 JP 5368085 A JP5368085 A JP 5368085A JP 5368085 A JP5368085 A JP 5368085A JP H0675306 B2 JPH0675306 B2 JP H0675306B2
- Authority
- JP
- Japan
- Prior art keywords
- magneto
- optical recording
- recording medium
- power
- optimum
- 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.)
- Expired - Lifetime
Links
- 239000000758 substrate Substances 0.000 claims description 14
- 239000010408 film Substances 0.000 description 33
- 230000001681 protective effect Effects 0.000 description 4
- 238000004544 sputter deposition Methods 0.000 description 4
- 229910052688 Gadolinium Inorganic materials 0.000 description 3
- 229910052771 Terbium Inorganic materials 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 230000015654 memory Effects 0.000 description 3
- 239000010409 thin film Substances 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 229910052692 Dysprosium Inorganic materials 0.000 description 2
- 229910052689 Holmium Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 230000005415 magnetization Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 229920003229 poly(methyl methacrylate) Polymers 0.000 description 2
- 239000004926 polymethyl methacrylate Substances 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 229910052723 transition metal Inorganic materials 0.000 description 2
- 150000003624 transition metals Chemical class 0.000 description 2
- 238000007740 vapor deposition Methods 0.000 description 2
- 239000004593 Epoxy Substances 0.000 description 1
- 229910002546 FeCo Inorganic materials 0.000 description 1
- 229910016629 MnBi Inorganic materials 0.000 description 1
- 229910002837 PtCo Inorganic materials 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
- 238000005546 reactive sputtering Methods 0.000 description 1
- 235000015067 sauces Nutrition 0.000 description 1
- 238000001771 vacuum deposition Methods 0.000 description 1
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は、レーザー光を用いて情報の記録再生消去をお
こなう光磁気記録媒体に関する。TECHNICAL FIELD The present invention relates to a magneto-optical recording medium for recording / reproducing / erasing information by using a laser beam.
（従来技術とその問題点） 光デイスクメモリは高密度・大容量・高速アクセスが可
能であるということから、現在の磁気デイスクメモリに
代わる新規なメモリとして考えられている。中でも光磁
気記録媒体を用いた光磁気デイスクは書き替え性を有し
ていることから最も注目され、近年活発に研究開発がお
こなわれている。(Prior Art and Its Problems) Optical disk memories are considered as a new memory to replace the current magnetic disk memories because they can be accessed with high density, large capacity and high speed. Among them, a magneto-optical disk using a magneto-optical recording medium has received the most attention because it has rewritability, and has been actively researched and developed in recent years.
従来より知られている光磁気記録媒体の構成は、第７図
に示したように支持基板１としてガラスあるいは有機物
樹脂を用い、支持基板１上に基板に対して垂直方向に磁
化を有する垂直磁化膜から成る光磁気記録層２を形成し
たものである。光磁気記録層としてはMnBi,MnCuBi,MnTi
Bi,MnAlGe,PtCoなどの結晶体磁性薄膜、あるいはGd,Tb,
Dy,Hoなどの希土類とFe,Co,Niなどの遷移金属との合金
として得られるアモルフアス磁性薄膜が知られている。
また、第８図に示したように、支持基板１に深さ600〜1
000Å周期1.6〜2.5μｍの溝を同心円状もしくはうず巻
き状に形成し、前記支持基板１上に光磁気記録層２を形
成した媒体構成も知られている。ここで形成されている
溝11は、記録媒体への情報の記録、あるいは再生・消去
に用いるレーザ集光ビームのトラツキングアクセスに用
いられるものである。The structure of a magneto-optical recording medium which has been conventionally known is such that, as shown in FIG. 7, glass or an organic resin is used as the supporting substrate 1, and the perpendicular magnetization having the magnetization in the direction perpendicular to the substrate is used on the supporting substrate 1. The magneto-optical recording layer 2 made of a film is formed. MnBi, MnCuBi, MnTi as the magneto-optical recording layer
Bi, MnAlGe, PtCo and other crystalline magnetic thin film, or Gd, Tb,
Amorphous magnetic thin films obtained as alloys of rare earths such as Dy and Ho and transition metals such as Fe, Co and Ni are known.
In addition, as shown in FIG.
There is also known a medium structure in which a groove having a 000Å period of 1.6 to 2.5 μm is formed in a concentric circle shape or a spiral shape, and the magneto-optical recording layer 2 is formed on the support substrate 1. The groove 11 formed here is used for tracking access of a laser focused beam used for recording or reproducing / erasing information on a recording medium.
従来より知られている第７図及び第８図に示された光磁
気記録媒体においては、支持基板１上の光磁気記録層２
の膜厚に関して特に工夫はされていない。通常、半径方
向の膜厚分布は一定となるように形成されている。光磁
気記録媒体を用いて情報再生消去をおこなう場合、等角
速度で媒体を回転すると半径位置によつて媒体の線速度
が変わる。半径方向に一様な膜厚分布を持つ従来の光磁
気記録媒体においては最適記録パワー、最適再生パワ
ー、最適消去パワー各パワーを半径位置に応じて変えな
ければならない（川久保ら、電子通信学会技術研究報告
MR84-39）という欠点があつた。In the conventionally known magneto-optical recording medium shown in FIGS. 7 and 8, the magneto-optical recording layer 2 on the support substrate 1 is used.
No special measures have been taken regarding the film thickness of. Usually, the film thickness distribution in the radial direction is formed to be constant. When information reproduction / erasure is performed using a magneto-optical recording medium, when the medium is rotated at a constant angular velocity, the linear velocity of the medium changes depending on the radial position. In the conventional magneto-optical recording medium having a uniform film thickness distribution in the radial direction, the optimum recording power, the optimum reproducing power, and the optimum erasing power must be changed according to the radial position (Kawakubo et al. Research report
MR84-39) has a drawback.
（発明の目的） 本発明の目的は、前記従来の光磁気記録媒体の欠点を解
決し、簡単な媒体構成により、線速に依存することなく
半径方向に対して一定の最適記録パワー、最適再生パワ
ー、最適消去パワーを有し、良好な記録再生消去性能を
持つ新規な光磁気記録媒体を提供することにある。(Object of the Invention) An object of the present invention is to solve the above-mentioned drawbacks of the conventional magneto-optical recording medium and to provide a constant optimum recording power and optimum reproduction in the radial direction without depending on the linear velocity by a simple medium structure. It is an object of the present invention to provide a novel magneto-optical recording medium having power and optimum erasing power, and having excellent recording / reproducing / erasing performance.
（発明の構成） 上記目的を達成するために、本発明は、レーザ光を用い
て情報の記録再生消去をおこなう光磁気記録媒体におい
て、円板状支持基板と前記円板状支持基板上に形成され
た光磁気記録層とを備え、前記光磁気記録層の膜厚が光
磁気記録媒体の外周ほど薄くなるようにしたものであ
る。(Structure of the Invention) In order to achieve the above object, the present invention is a magneto-optical recording medium for recording / reproducing / erasing information by using a laser beam, which is formed on a disk-shaped support substrate and the disk-shaped support substrate. The magneto-optical recording layer is formed so that the film thickness of the magneto-optical recording layer becomes thinner toward the outer circumference of the magneto-optical recording medium.
（構成の詳細な説明） 本発明は上述の構成をとることにより、従来技術の問題
点を解決した。以下、本発明の詳細について図面を用い
て説明する。第１図は本発明にかかる光磁気記録媒体の
一例を示す断面図である。支持基板１上に光磁気記録層
２が形成された構造である。支持基板１としてはポリメ
チルメタクリレート、ポリカーボネート、エポキシなど
の有機物樹脂材料あるいはガラスが使用され、第２図の
ようにレーザビームトラツキング用の溝11があらかじめ
形成されたタイプのものも使用される。(Detailed Description of Configuration) The present invention has solved the problems of the prior art by adopting the above configuration. Hereinafter, details of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing an example of a magneto-optical recording medium according to the present invention. This is a structure in which the magneto-optical recording layer 2 is formed on the support substrate 1. As the supporting substrate 1, an organic resin material such as polymethylmethacrylate, polycarbonate, epoxy or glass is used, and a type in which a groove 11 for laser beam tracking is formed in advance as shown in FIG. 2 is also used.
光磁気記録層２としてはGd,Tb,Dy,Hoなどの希土類金属
とFe,Co,Niなどの遷移金属との合金から成るアモルフア
ス磁性薄膜が用いられる。たとえば、GdCo,GdTbCo,GdTb
FeCo,TbFe,TbFeCo,TbDyFeCo,GdTbFe,GdTbDyFe,TbCo,TbD
yCo,TbFeNiなどである。光磁気記録層２は内周から外周
に向けて膜厚を変えて作成され、外周ほど膜厚が薄くな
つている。これが本発明にかかる光磁気記録媒体の特徴
である。光磁気記録層２は真空蒸着法、スパツタリング
法などの成膜方法により作成される。As the magneto-optical recording layer 2, an amorphous magnetic thin film made of an alloy of a rare earth metal such as Gd, Tb, Dy and Ho and a transition metal such as Fe, Co and Ni is used. For example, GdCo, GdTbCo, GdTb
FeCo, TbFe, TbFeCo, TbDyFeCo, GdTbFe, GdTbDyFe, TbCo, TbD
Examples are yCo and TbFeNi. The magneto-optical recording layer 2 is formed by changing the film thickness from the inner circumference to the outer circumference, and the film thickness becomes thinner toward the outer circumference. This is a feature of the magneto-optical recording medium according to the present invention. The magneto-optical recording layer 2 is formed by a film forming method such as a vacuum evaporation method and a sputtering method.
光磁気記録層２の膜厚が外周に向けて薄くなるように成
膜するには、例えば第３図に示したように真空室５中に
デイスク３の回転中心に対して偏心した位置に蒸着源あ
るいはスパツタソース４を有する成膜装置を用いる。図
中８は排気系、９は導入ガスボンベである。デイスク３
をモータ10により回転させながら成膜することにより、
半径方向に所望の膜厚分布を持つ光磁気記録媒体が容易
に得られる。To form the magneto-optical recording layer 2 so that the film thickness becomes thinner toward the outer circumference, for example, as shown in FIG. 3, vapor deposition is performed in a vacuum chamber 5 at a position eccentric to the rotation center of the disk 3. A film forming apparatus having a source or a sputtering source 4 is used. In the figure, 8 is an exhaust system, and 9 is an introduced gas cylinder. Disk 3
By forming a film while rotating the
A magneto-optical recording medium having a desired film thickness distribution in the radial direction can be easily obtained.
第４図（ａ）（ｂ）（ｃ）は、それぞれ光磁気記録媒体
の最適記録パワー、最適再生パワー、最適消去パワーと
線速度との関係を示した図である。パラメータとして光
磁気記録層の膜厚をとつている。ここで言う最適記録パ
ワーとは、記録信号に最も忠実に記録ビツトが形成でき
る記録パワーである。FIGS. 4 (a), (b) and (c) are diagrams showing the relationships between the optimum recording power, the optimum reproducing power, the optimum erasing power and the linear velocity of the magneto-optical recording medium. The parameter is the film thickness of the magneto-optical recording layer. The optimum recording power mentioned here is a recording power that can form a recording bit most faithfully to a recording signal.
また最適再生パワーとは再生信号のC/N,すなわち再生信
号レベルと雑音レベルの比が最も大きくなる再生パワー
を言う。The optimum reproduction power is the reproduction power that maximizes the C / N of the reproduction signal, that is, the ratio between the reproduction signal level and the noise level.
さらに最適消去パワーとは最適記録されたビツトを完全
に消去できる消去パワーを言う。最適記録パワー、最適
再生パワー、最適消去パワーはいずれも線速が増すと高
パワー側にシフトする。また、光磁気記録層の膜厚が厚
くなると、同じ線速であつても最適となる各パワーは大
きくなる。光磁気記録媒体を等角速度で回転して用いる
場合、半径位置によつて線速度が大きく変わる。そこ
で、光磁気記録層の膜厚が半径方向に一定であると、第
４図（ａ）、（ｂ）、（ｃ）からわかるように最適な記
録パワー、再生パワー、消去パワーを半径位置に応じて
変化させなければならない。Furthermore, the optimum erasing power is the erasing power that can completely erase the optimum recorded bit. The optimum recording power, optimum reproduction power, and optimum erasing power all shift to the higher power side as the linear velocity increases. Further, as the film thickness of the magneto-optical recording layer becomes thicker, each optimum power becomes larger even at the same linear velocity. When the magneto-optical recording medium is used while being rotated at a constant angular velocity, the linear velocity greatly changes depending on the radial position. Therefore, when the thickness of the magneto-optical recording layer is constant in the radial direction, the optimum recording power, reproducing power, and erasing power are set at the radial position, as can be seen from FIGS. 4 (a), (b), and (c). Must be changed accordingly.
この欠点を解決するために、本発明にかかる光磁気記録
媒体の光磁気記録層の膜厚は第５図に示したように半径
方向に変化し、外周部ほど膜厚が減少するように作成さ
れる。In order to solve this drawback, the magneto-optical recording layer of the magneto-optical recording medium according to the present invention is formed so that the film thickness changes in the radial direction as shown in FIG. To be done.
（実施例−１） 深さ700Å、幅0.8μｍ、ピツチ2.5μｍのうず巻き状の
溝を有するポリメチルメタクリレート基板（120mm直
径、厚さ1.2mm）上にGdTbFe膜をスパツタリングによつ
て成膜した。成膜には第３図に示した構成の成膜装置を
用いた。デイスクは毎分20回転で回転され、直径60mmの
スパツタソース（Gd,Tb,Feの複合型ターゲツト）はデイ
スク回転中心から30mm離れた位置に配置された。２×10
-7Torr以下に排気後、アルゴンガス圧を７×10-3Torrに
設定し、スパツタをおこなつた。５分間のスパツタによ
り、半径方向に膜厚が変化した光磁気記録媒体が作成で
きた。半径29mmでのGdTbFeの膜厚は2000Å、半径58mmで
の膜厚は1000Åであつた。Example 1 A GdTbFe film was formed by sputtering on a polymethylmethacrylate substrate (120 mm diameter, 1.2 mm thickness) having a spiral wound groove with a depth of 700 Å, a width of 0.8 μm and a pitch of 2.5 μm. The film forming apparatus having the configuration shown in FIG. 3 was used for film forming. The disk was rotated at 20 rpm, and a spatula sauce (composite target of Gd, Tb, Fe) with a diameter of 60 mm was placed 30 mm away from the center of rotation of the disk. 2 x 10
After evacuating to -7 Torr or less, the argon gas pressure was set to 7 × 10 -3 Torr and spattering was performed. By a spatula for 5 minutes, a magneto-optical recording medium having a film thickness varied in the radial direction could be prepared. The film thickness of GdTbFe at a radius of 29 mm was 2000Å and that at a radius of 58 mm was 1000Å.
次に、作成した光磁気記録媒体を用いて情報の記録再生
消去をおこなつた。媒体を毎秒30回転で回転し、記録再
生消去をおこなつたところ、半径29mmから58mmにおい
て、最適な記録パワー、再生パワー、消去パワーはそれ
ぞれ一定であり、良好な記録再生消去が可能であつた。Next, information was recorded / reproduced / erased using the prepared magneto-optical recording medium. When the medium was rotated at 30 rpm and recording / reproducing was performed, the optimum recording power, reproducing power, and erasing power were constant at a radius of 29 mm to 58 mm, and good recording / reproducing was possible. .
（実施例−２） 実施例−１で用いたものと同じ基板上に、まず保護膜兼
干渉層としてSi3N4膜を反応性スパツタリングにより成
膜した。On the same substrate as that used in (Example - 2) in Example 1, and the first the Si 3 N 4 film as a protective film and the interference layer is formed by reactive Supatsutaringu.
膜厚は内周から外周にかけて一様に1200Åとなるように
した。つづいて真空を破ることなく実施例−１と同様の
手法でGdTbFe膜を成膜した。膜厚は半径29mmでは2000
Å、半径58mmでは1000Åであつた。さらにGdTbFe膜上
に、保護膜として2000Å厚のSi3N4膜を反応性スパツタ
リングにより成膜した。本実施例にもとづく光磁気記録
媒体の断面図は第６図のようになつている。The film thickness was made to be 1200Å uniformly from the inner circumference to the outer circumference. Subsequently, a GdTbFe film was formed by the same method as in Example-1 without breaking the vacuum. The film thickness is 2000 when the radius is 29 mm
Å, 1000Å at a radius of 58 mm. Furthermore, a 2000Å thick Si 3 N 4 film was formed as a protective film on the GdTbFe film by reactive sputtering. A sectional view of the magneto-optical recording medium according to this embodiment is shown in FIG.
次に、作成した光磁気記録媒体を毎秒30回転で回転さ
せ、情報の記録再生消去をおこなつた。半径29mmから58
mmにおいて、最適となる記録パワー、再生パワー、消去
パワーはそれぞれ一定であり、良好な記録再生消去特性
が得られた。Next, the produced magneto-optical recording medium was rotated at 30 revolutions per second to record / reproduce / erase information. Radius 29mm to 58
In mm, the optimum recording power, reproducing power, and erasing power were constant, and good recording / reproducing / erasing characteristics were obtained.
（発明の効果） 以上、説明したように本発明によれば従来例と比較して
次のような効果がある。(Effect of the Invention) As described above, the present invention has the following effects as compared with the conventional example.
等角速度回転での使用において光磁気記録媒体の半
径方向に対して最適記録パワー、最適再生パワー、最適
消去パワーが一定となるように媒体設計されているの
で、従来例のように半径位置に応じて各パワーを変える
必要がなく、装置構成を簡略化できる。Since the medium is designed so that the optimum recording power, optimum reproducing power, and optimum erasing power are constant in the radial direction of the magneto-optical recording medium when it is used at a constant angular velocity, it depends on the radial position as in the conventional example. Therefore, it is not necessary to change each power, and the device configuration can be simplified.
蒸着源あるいはスパツタソースの位置に対してデイ
スクの回転中心を偏心させることにより、容易に半径方
向に所望の膜厚分布を持つ媒体が作成できる。By eccentricizing the rotation center of the disk with respect to the position of the vapor deposition source or the sputtering source, it is possible to easily create a medium having a desired film thickness distribution in the radial direction.
本発明は等角速度回転で用いる光磁気記録媒体すべ
てに適用できる。すなわち、本発明の実施例に限らず、
種々の光磁気記録材料を用いた種々の膜構成の光磁気記
録媒体に適用できる。The present invention can be applied to all magneto-optical recording media used at a constant angular velocity rotation. That is, not limited to the embodiment of the present invention,
It can be applied to magneto-optical recording media having various film structures using various magneto-optical recording materials.
第１図及び第２図は本発明の適用された光磁気記録媒体
の構成例を示す断面図、第３図は本発明にかかる光磁気
記録媒体の作成に用いる成膜装置の概略図、第４図
（ａ）、（ｂ）、（ｃ）は光磁気記録媒体の最適記録パ
ワー、最適再生パワー、最適消去パワーと線速度との関
係を示した図、第５図は本発明にかかる光磁気記録媒体
の光磁気記録層の半径方向の膜厚分布を示す図、第６図
は本発明の適用された一実施例の断面図である。第７
図、第８図は従来の光磁気記録媒体の構成を示す断面図
である。 図中１……支持基板、２……光磁気記録層、３……デイ
スク、４……蒸着源あるいはスパツタソース、５……真
空室、６……保護膜兼干渉層、７……保護膜、８……排
気系、９……導入ガスボンベ、10……モーター、11……
溝である。1 and 2 are cross-sectional views showing an example of the structure of a magneto-optical recording medium to which the present invention is applied, and FIG. 3 is a schematic view of a film forming apparatus used for producing the magneto-optical recording medium according to the present invention. 4 (a), (b) and (c) are diagrams showing the relationship between the optimum recording power, the optimum reproducing power, the optimum erasing power and the linear velocity of the magneto-optical recording medium, and FIG. FIG. 6 is a diagram showing the radial thickness distribution of the magneto-optical recording layer of the magnetic recording medium, and FIG. 6 is a sectional view of an embodiment to which the present invention is applied. 7th
FIG. 8 is a sectional view showing the structure of a conventional magneto-optical recording medium. In the figure, 1 ... Support substrate, 2 ... Magneto-optical recording layer, 3 ... Disk, 4 ... Deposition source or sputter source, 5 ... Vacuum chamber, 6 ... Protective film / interference layer, 7 ... Protective film, 8 ... Exhaust system, 9 ... Introduced gas cylinder, 10 ... Motor, 11 ...
It is a groove.
Claims (1)
こなう光磁気記録媒体において、円板状支持基板と前記
円板状支持基板上に形成された光磁気記録層とを備え、
前記光磁気記録層の膜厚が光磁気記録媒体の外周ほど薄
くなっていることを特徴とする光磁気記録媒体。1. A magneto-optical recording medium for recording / reproducing / erasing information by using a laser beam, comprising: a disc-shaped supporting substrate; and a magneto-optical recording layer formed on the disc-shaped supporting substrate.
A magneto-optical recording medium, wherein the thickness of the magneto-optical recording layer is thinner toward the outer periphery of the magneto-optical recording medium.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5368085A JPH0675306B2 (en) | 1985-03-18 | 1985-03-18 | Magneto-optical recording medium |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5368085A JPH0675306B2 (en) | 1985-03-18 | 1985-03-18 | Magneto-optical recording medium |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61211854A JPS61211854A (en) | 1986-09-19 |
| JPH0675306B2 true JPH0675306B2 (en) | 1994-09-21 |
Family
ID=12949530
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5368085A Expired - Lifetime JPH0675306B2 (en) | 1985-03-18 | 1985-03-18 | Magneto-optical recording medium |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0675306B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01253848A (en) * | 1988-03-31 | 1989-10-11 | Matsushita Electric Ind Co Ltd | Information recording carrier |
| JP2616058B2 (en) * | 1989-11-01 | 1997-06-04 | 日本電気株式会社 | Magneto-optical disk |
-
1985
- 1985-03-18 JP JP5368085A patent/JPH0675306B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61211854A (en) | 1986-09-19 |
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| EXPY | Cancellation because of completion of term |