TWI394179B - Structure and Method of Ultra - thin Ferromagnetic / Antiferromagnetic Coupling Thin Films - Google Patents
Structure and Method of Ultra - thin Ferromagnetic / Antiferromagnetic Coupling Thin Films Download PDFInfo
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- TWI394179B TWI394179B TW096141973A TW96141973A TWI394179B TW I394179 B TWI394179 B TW I394179B TW 096141973 A TW096141973 A TW 096141973A TW 96141973 A TW96141973 A TW 96141973A TW I394179 B TWI394179 B TW I394179B
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- film
- cobalt
- layer
- ferromagnetic
- thickness
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- 230000005290 antiferromagnetic effect Effects 0.000 title claims description 42
- 230000005294 ferromagnetic effect Effects 0.000 title claims description 40
- 230000008878 coupling Effects 0.000 title claims description 25
- 238000010168 coupling process Methods 0.000 title claims description 25
- 238000005859 coupling reaction Methods 0.000 title claims description 25
- 238000000034 method Methods 0.000 title claims description 13
- 239000010409 thin film Substances 0.000 title description 3
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 54
- 229910017052 cobalt Inorganic materials 0.000 claims description 53
- 239000010941 cobalt Substances 0.000 claims description 53
- 229910000428 cobalt oxide Inorganic materials 0.000 claims description 23
- IVMYJDGYRUAWML-UHFFFAOYSA-N cobalt(ii) oxide Chemical compound [Co]=O IVMYJDGYRUAWML-UHFFFAOYSA-N 0.000 claims description 21
- 239000000758 substrate Substances 0.000 claims description 18
- 238000007747 plating Methods 0.000 claims description 13
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 229910052760 oxygen Inorganic materials 0.000 claims description 6
- 239000001301 oxygen Substances 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 4
- 230000015572 biosynthetic process Effects 0.000 claims description 2
- 239000010408 film Substances 0.000 description 87
- 230000005291 magnetic effect Effects 0.000 description 22
- 239000000779 smoke Substances 0.000 description 10
- 239000012636 effector Substances 0.000 description 7
- 238000005259 measurement Methods 0.000 description 7
- 238000000137 annealing Methods 0.000 description 6
- 238000001816 cooling Methods 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 5
- 230000007423 decrease Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 229910020647 Co-O Inorganic materials 0.000 description 3
- 229910020704 Co—O Inorganic materials 0.000 description 3
- 230000001808 coupling effect Effects 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 238000000682 scanning probe acoustic microscopy Methods 0.000 description 3
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 2
- 238000005273 aeration Methods 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 229910002521 CoMn Inorganic materials 0.000 description 1
- 229910015475 FeF 2 Inorganic materials 0.000 description 1
- 229910015136 FeMn Inorganic materials 0.000 description 1
- 229910001030 Iron–nickel alloy Inorganic materials 0.000 description 1
- 229910003289 NiMn Inorganic materials 0.000 description 1
- 229910019041 PtMn Inorganic materials 0.000 description 1
- 125000004429 atom Chemical group 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000001941 electron spectroscopy Methods 0.000 description 1
- 229910052741 iridium Inorganic materials 0.000 description 1
- 230000005415 magnetization Effects 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 125000004430 oxygen atom Chemical group O* 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000002207 thermal evaporation Methods 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 229910000314 transition metal oxide Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/58—After-treatment
- C23C14/5846—Reactive treatment
- C23C14/5853—Oxidation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y25/00—Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
- C23C14/14—Metallic material, boron or silicon
- C23C14/16—Metallic material, boron or silicon on metallic substrates or on substrates of boron or silicon
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/127—Structure or manufacture of heads, e.g. inductive
- G11B5/33—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only
- G11B5/39—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only using magneto-resistive devices or effects
- G11B5/3903—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only using magneto-resistive devices or effects using magnetic thin film layers or their effects, the films being part of integrated structures
- G11B5/3906—Details related to the use of magnetic thin film layers or to their effects
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F10/00—Thin magnetic films, e.g. of one-domain structure
- H01F10/32—Spin-exchange-coupled multilayers, e.g. nanostructured superlattices
- H01F10/3218—Exchange coupling of magnetic films via an antiferromagnetic interface
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/14—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for applying magnetic films to substrates
- H01F41/20—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for applying magnetic films to substrates by evaporation
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S428/00—Stock material or miscellaneous articles
- Y10S428/90—Magnetic feature
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/11—Magnetic recording head
- Y10T428/1107—Magnetoresistive
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
- Y10T428/24942—Structurally defined web or sheet [e.g., overall dimension, etc.] including components having same physical characteristic in differing degree
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- Materials Engineering (AREA)
- Crystallography & Structural Chemistry (AREA)
- Nanotechnology (AREA)
- Manufacturing & Machinery (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Thin Magnetic Films (AREA)
- Magnetic Heads (AREA)
Description
本發明是有關於一種超薄鐵磁/反鐵磁耦合薄膜之結構及其製法，且特別是有關於一種用於自旋閥多層膜結構的鐵磁/反鐵磁耦合薄膜之結構及其製法。
記錄媒體可依其記錄方式概分為磁記錄、光記錄、磁光記錄及半導體記錄媒體，主要仍係以磁記錄與光記錄為主。由鐵磁層與非鐵磁層交替成長而成的磁性多層膜中的巨磁阻現象已被用於作為讀取磁頭，吸引了廣泛的研究，具有交換耦合效應之自旋閥(spin valve)多層膜則被視為最具潛力的系統。
自旋閥的多層膜結構包括反鐵磁層/鐵磁層一/分隔層/鐵磁層二，其中反鐵磁層與鐵磁層之交換耦合效應係自旋閥系統之關鍵性質。一般在鐵磁層與反鐵磁層的交換磁異向性研究中，鐵磁層多為Fe、Co或NiFe等3d過渡鐵磁性金屬。反鐵磁層的種類則大致可分為(1)鐵磁性金屬氧化物，例如CoO、NiO等薄膜；(2)Mn系與鐵磁性金屬的合金，例如FeMn、NiMn、CoMn等薄膜；(3)Mn與其他過渡金屬的合金，例如PtMn、PdMn、IrMn等薄膜；或(4)其他金屬薄膜，例如FeF2
等。
由於交換偏壓耦合現象最先係從Co與其表面氧化層的微小粒子中發現，另一方面，CoO與NiO等薄膜之絕緣性過渡金屬氧化物反鐵磁薄膜，不論在化學或磁性結構方面均具有簡單且穩定之特性，亦具有相當好的抗腐蝕性與抗氧化性，應用於自旋閥系統中，可避免發生分電流效應。
然而，目前仍缺乏一種能夠應用於自旋閥多層膜結構之超薄層狀鐵磁/反鐵磁薄膜結構與製造方法。
本發明之主要目的係在於提供一種超薄的鐵磁/反鐵磁薄膜之結構及其製法。
本發明之又一目的係在於提供一種可用於自旋閥式巨磁阻磁頭系統的鐵磁/反鐵磁薄膜之結構及其製法。
為達上述及其他目的，本發明提供一種鐵磁/反鐵磁耦合薄膜之結構，包括基材、於700至900 K之溫度條件下，形成於基材表面厚度為2至15原子層之氧化鈷反鐵磁層、以及形成於氧化鈷反鐵磁層表面至少1原子層之鈷膜鐵磁層。本發明亦提供一種製造鐵磁/反鐵磁耦合薄膜結構之方法，該方法主要係先於基材表面鍍上至少2原子層之第一鈷膜，接著使該第一鈷膜曝氧至飽和並於700至900 K之溫度條件下加熱使氧與鈷均勻化合形成厚度為2至15原子層之氧化鈷層，再於該氧化鈷層表面鍍上第二鈷膜而形成鐵磁/反鐵磁耦合薄膜之結構。該薄膜結構經場冷卻後，利用表面磁光科爾效應儀進行磁性量測，發現磁滯偏移現象，為良好的鐵磁/反鐵磁薄膜。藉由調整反鐵磁層的厚度，可以改變交換耦合的強度，獲得鐵磁層與反鐵磁層交換耦合的最佳條件，特別適合用於磁記錄媒體。
以下係藉由特定之具體實施例配合附圖進一步說明本發明之特點與功效。
本發明之鐵磁/反鐵磁耦合薄膜結構，包括基材、形成於基材表面之氧化鈷反鐵磁層、以及形成於氧化鈷反鐵磁層表面之鈷膜鐵磁層。在鈷與氧化鈷系統中所發現的交換偏壓(Exchange bias)會導致磁滯偏移的現象，而本發明之薄膜結構中，增加氧化鈷反鐵磁層之厚度可以獲得更明顯之磁滯偏移。因此，在本發明之耦合薄膜結構中，藉由調整該氧化鈷反鐵磁層之厚度，可以獲得較佳的鐵磁層與反鐵磁層耦合條件。於一具體實例中，本發明之耦合薄膜結構係具有2至15原子層之氧化鈷反鐵磁層，較佳係具有2至8原子層之氧化鈷反鐵磁層，更佳係具有2至4原子層之氧化鈷反鐵磁層。
另一方面，在特定溫度條件下，該鐵磁/反鐵磁耦合薄膜之極向偏移場(HE
)與鈷膜鐵磁層的厚度呈現反比。因此，本發明之耦合薄膜結構具有1至15原子層之鈷膜鐵磁層，較佳係具有1至8原子層之鈷膜鐵磁層，更佳係具有1至4原子層之鈷膜鐵磁層。
本發明用於製造鐵磁/反鐵磁耦合薄膜之方法，包括(a)於基材表面鍍上至少2原子層之第一鈷膜；(b)使該第一鈷膜曝氧至飽和；(c)於700至900 K之溫度條件下加熱使氧與鈷均勻化合形成厚度為2至15原子層之氧化鈷層，較佳形成厚度為2至8原子層之氧化鈷層，更佳形成厚度為2至4原子層之氧化鈷層；以及(d)於該氧化鈷層表面鍍上至少1原子層之第二鈷膜。
步驟(a)係於超高真空的環境中進行。首先，將基材置於真空度維持在10－9
Torr以上之超高真空的環境中，以Ar離子轟擊基材表面。利用歐傑電子能譜(AES)以高能量的電子或光激發基材的內層電子而留下電洞，經由外層電子填滿電洞釋放出歐傑電子(Auger electron)，藉以判別表面成分。
接著加熱退火樣品表面，確定樣品表面結構後再以熱蒸鍍的方式鍍膜。由於鈷可以直接昇華，因此採用直熱式的設計。將鈷鍍源製作好後，直接在電子透(feedthrough)上接上轉接頭(adapter)，將鍍源固定於轉接頭上。直接由電子透上通與約3.9安培之工作電流，即可使鈷鍍源發熱，放出鈷原子，進行基材表面之鍍鈷(基材溫度約為300K)。鍍鈷時間間隔為五分鐘，並利用歐傑電子能譜確認表面組成與膜厚。重複進行鍍鈷的步驟，直到基材表面形成所需厚度之鈷膜，例如約為1至15原子層之鈷膜，較佳約為1至8原子層之鈷膜，更佳約為1至4原子層之鈷膜。
步驟(b)係使鍍有鈷膜之基材進行曝氧至飽和。
步驟(c)係使曝氣完成後之薄膜樣品加熱退火歷時十分鐘，使氧與鈷均勻化合形成氧化鈷層。
提高加熱退火之溫度可以獲得較大的磁滯偏移量，本發明之方法較佳係於700至900K之溫度條件下進行該加熱退火之步驟。當溫度高於900 K，Co會開始往銥(Ir)基材擴散，破壞CoO層結構，不利於交換耦合現象。另一方面，當加熱退火之溫度低於700 K時，由於溫度不夠高，CoO無法形成良好晶體結構，導致無交換耦合現象。
待薄膜樣品溫度降低至350 K以下，再進行步驟(d)，於該形成有氧化鈷之基材表面蒸鍍上1至15原子層之鈷薄膜，較佳蒸鍍上1至8原子層之鈷薄膜，更佳蒸鍍上1至4原子層之鈷薄膜，形成氧/鈷/氧化鈷(O/Co/CoO)的介面。對此薄膜結構之樣品外加1000 Oe之磁場進行場冷卻，在230至300 K之不同溫度條件下，以表面磁光柯爾效應儀(SMOKE)進行磁性量測，發現磁滯曲線偏移的現象，顯示薄膜樣品為超薄層狀鐵磁/反鐵磁薄膜。薄膜矯頑力(coercivity，HC
)於溫度230至300K之範圍內，係隨溫度上升而減少。另一方面，極向偏移場(HE
)則係於溫度250至300K之範圍內，隨溫度上升而減少。
以下藉由實施例詳細說明本發明的特點及功效。惟該實施例之內容僅用以闡述本發明，而非用以限制本發明的範疇。
於背景壓力約5×10－10
Torr之超高真空環境下製作薄膜樣品並進行表面特性量測。使用歐傑電子能譜儀來確定表面原子的相對濃度並以表面磁光柯爾效應儀觀察樣品表面的磁性性質。模擬計算Co 775 eV與Ir 229 eV的歐傑電子訊號比在不同鈷厚度下之理論值，再與實驗上所求得之歐傑電子能譜所提供的相對濃度關係相比對，以求得鈷在銥(111)面上的薄膜厚度。
在超高真空環境下，先以Ar＋
離子反覆濺射並且加熱退火Ir(111)樣品。接著，讓樣品降到室溫300 K左右，以歐傑電子能譜儀測量C與Ir(111)的歐傑訊號強度比，待訊號強度比低於0.2開始鍍鈷。鍍鈷的時間間格為五分鐘，每次鍍鈷結束後以歐傑電子能譜儀測量，觀察樣品的表面組成及變化。當鈷薄膜厚度達到2 ML時，進行曝氧至飽和再將樣品加熱退火至850 K十分鐘。接著，蒸鍍1 ML鈷薄膜，由於氧原子的分凝(segregation)現象，形成具有O/1 ML Co/2 ML CoO/Ir(111)結構之薄膜樣品1。於外加磁場1000 Oe之條件下，對薄膜樣品1進行場冷卻，分別在250K、260K、270K、280K、290K、300K之溫度條件下以表面磁光柯爾效應儀進行磁性量測，測量結果如第1(a)至1(d)圖所示。
重複實施例1之步驟製作薄膜樣品，將加熱退火之溫度改為700K，形成具有O/1 ML Co/2 ML CoO/Ir(111)結構之薄膜樣品2。對薄膜樣品2進行場冷卻，在235K之條件下以表面磁光柯爾效應儀進行磁性量測，測量結果如第2圖所示，有產生磁滯偏移的現象。結果顯示，相較於薄膜樣品1，降低熱退火溫度之薄膜樣品2的磁滯偏移量較小。
重複實施例1之步驟製作薄膜樣品，形成具有O/1 ML Co/4 ML CoO/Ir(111)結構之薄膜樣品3。於外加磁場1000 Oe之條件下，對薄膜樣品3進行場冷卻，分別在230K、245K、260K、275K、290K、300K之溫度條件下以表面磁光柯爾效應儀進行磁性量測，測量結果如第3(a)至3(d)圖所示。顯示增加反鐵磁層厚度為4 ML CoO薄膜，磁滯偏移更加明顯，極向HC
值在樣品溫度230 K到300K之間隨樣品溫度上升減少。
重複實施例1之步驟製作樣品，分別形成具有1 ML、2 ML、3 ML、及4 ML等不同鈷薄膜厚度之樣品。於外加磁場1000 Oe之條件下，對薄膜樣品進行場冷卻，分別在230K、245K、260K、275K、290K、300K之溫度條件下以表面磁光柯爾效應儀進行磁性量測，極向偏移場與溫度關係如第4圖所示。極向偏移場HE
值在樣品溫度250 K到300 K之間呈現隨樣品溫度上升而減少的趨勢。極向偏移場與鈷薄膜厚度關係如第5圖所示，HE
值大小與鈷膜厚度呈現反比關係，樣品溫度低於275 K才有HE
值的變化。
重覆實施例1之步驟，先成長3 ML Co再曝氧氣完成後，於600K之條件下進行加熱退火，其上再長上1 ML Co形成1 ML Co/3 ML Co－O/Ir之結構樣品，降溫至250 K後量測磁性訊號，發現此樣品磁化曲線為具有左右對稱性，而不具交換耦合特性，如圖6所示。這一結果顯示當加熱退火溫度不夠高的情況下，CoO無法形成良好晶體結構，使得其後鍍上Co形成Co/Co－O介面不具交換耦合特性。
本發明用於製造鐵磁/反鐵磁耦合薄膜之方法可以形成數個原子層厚度之鈷/氧化鈷超薄膜，為最薄的層狀鐵磁/反鐵磁結構，能夠有效縮小磁性元件尺寸，特別適合用於自旋閥式的巨磁阻磁頭系統或磁記憶媒體。
惟上述實施例僅為例示性說明本發明之原理及其功效，並非用於限制本發明，任何熟習此項技藝之人士均可在不違背本發明之精神及範疇下，對上述實施例進行修飾與變化。因此，本發明之權利保護範圍，應如後述之申請專利範圍所列。
第1(a)圖係顯示根據本發明實施例1所形成具有O/1 ML Co/2 ML CoO/Ir(111)結構之薄膜樣品1在不同溫度的極向SMOKE圖；第1(b)圖係顯示根據本發明實施例1所形成具有O/1 ML Co/2 ML CoO/Ir(111)結構之薄膜樣品1在不同溫度的縱向SMOKE圖；第1(c)圖係顯示根據本發明實施例1所形成具有O/1 ML Co/2 ML CoO/Ir(111)結構之薄膜樣品1在300 K的極向SMOKE圖；第1(d)圖係顯示根據本發明實施例1所形成具有O/1 ML Co/2 ML CoO/Ir(111)結構之薄膜樣品1在300 K的縱向SMOKE圖；第2圖係顯示根據本發明實施例2所形成具有O/1 ML Co/2 ML CoO/Ir(111)結構之薄膜樣品2，在235K溫度條件之極向表面磁光科爾效應圖；第3(a)圖係顯示根據本發明實施例3所形成具有O/1 ML Co/4 ML CoO/Ir(111)結構之薄膜樣品3在不同溫度的極向SMOKE圖；第3(b)圖係顯示根據本發明實施例3所形成具有O/1 ML Co/4 ML CoO/Ir(111)結構之薄膜樣品3在不同溫度的縱向SMOKE圖；第3(c)圖係顯示根據本發明實施例3所形成具有O/1 ML Co/4 ML CoO/Ir(111)結構之薄膜樣品3在300 K的極向SMOKE圖；第3(d)圖係顯示根據本發明實施例3所形成具有O/1 ML Co/4 ML CoO/Ir(111)結構之薄膜樣品3在300 K的縱向SMOKE圖；第4圖係顯示根據本發明實施例4－7所形成具有不同鈷薄膜厚度之薄膜樣品的極向偏移場與溫度關係；第5圖係顯示根據本發明實施例4－7所形成之薄膜樣品的極向偏移場與鈷薄膜厚度關係；以及第6圖係顯示根據本發明比較例1所形成之薄膜樣品在250 K的極向SMOKE圖。
Claims (8)
- 一種超薄鐵磁/反鐵磁耦合薄膜結構，包括：基材；於700至900 K之溫度條件下，形成於基材表面厚度為2至15原子層之氧化鈷反鐵磁層；以及形成於氧化鈷反鐵磁層表面厚度為1至8原子層之鈷膜鐵磁層。
- 如申請專利範圍第1項之鐵磁/反鐵磁耦合薄膜結構，其中，該反鐵磁層厚度為2至8原子層。
- 如申請專利範圍第1項之鐵磁/反鐵磁耦合薄膜結構，其中，該反鐵磁層厚度為2至4原子層。
- 如申請專利範圍第1項之鐵磁/反鐵磁耦合薄膜結構，其中，鐵磁層厚度為1至4原子層。
- 一種製造鐵磁/反鐵磁耦合薄膜之方法，包括下列步驟：(a)於基材表面鍍上至少2原子層之第一鈷膜；(b)使該第一鈷膜曝氧至飽和；(c)於700至900 K之溫度條件下加熱使氧與鈷均勻化合形成厚度為2至15原子層之氧化鈷層；(d)於該氧化鈷層表面鍍上厚度為1至8原子層之第二鈷膜。
- 如申請專利範圍第5項之方法，其中，該第一鈷膜層厚度為2至8原子層。
- 如申請專利範圍第5項之方法，其中，該第一鈷膜層 厚度為2至4原子層。
- 如申請專利範圍第5項之方法，其中，該第二鈷膜層厚度為1至4原子層。
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| US3110613A (en) * | 1960-09-19 | 1963-11-12 | Charles P Bean | Magnetic material |
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| FR1524309A (fr) * | 1967-03-29 | 1968-05-10 | Centre Nat Rech Scient | Mémoires d'informations binaires à structures magnétiques en couches minces |
| DE2365178C2 (de) * | 1973-12-29 | 1982-07-01 | Basf Ag, 6700 Ludwigshafen | Verfahren zur Herstellung von magnetischen Materialien mit Austauschanisotropieverhalten |
| US4581109A (en) * | 1983-12-12 | 1986-04-08 | Digital Equipment Corporation | Magnetic plated media and process thereof |
| JPH0983039A (ja) * | 1995-09-14 | 1997-03-28 | Nec Corp | 磁気抵抗効果素子 |
| JPH09205234A (ja) * | 1996-01-26 | 1997-08-05 | Nec Corp | 磁気抵抗効果素子及び磁気抵抗効果センサ |
| JP2856165B2 (ja) * | 1996-08-12 | 1999-02-10 | 日本電気株式会社 | 磁気抵抗効果素子及びその製造方法 |
| JPH10198927A (ja) * | 1997-01-08 | 1998-07-31 | Nec Corp | 磁気抵抗効果膜およびその製造方法 |
| JP2000011331A (ja) * | 1998-06-18 | 2000-01-14 | Tdk Corp | 磁気抵抗効果素子及び薄膜磁気ヘッド |
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