TW448430B - Method for forming magneto-resistance effect film - Google Patents

Abstract

The purpose of the present invention is to provide a method for forming a magneto-resistance effect film, enabling manufacture of a magneto-resistive device having a high MR ratio by improving the flatness of the interfaces between layers without deteriorating the crystallinity of a multilayer film. The method for forming a magneto-resistance effect film includes a free magnetization layer, a nonmagnetic layer, a fixed magnetization layer, and an anti-ferromagnetic layer on a predetermined substrate in order or in the reverse order, which is characterized by: it comprises at least the step of disposing the substrate in a film-forming chamber, lowering the degree of vacuum in the film-forming chamber below 10<SP>-10</SP> Torr, introducing at least an oxygen-containing gas (a) into the film-forming chamber, changing the degree of vacuum in the film-forming chamber to a constant pressure in a range from 3x10<SP>-9</SP> Torr to 1x10<SP>-8</SP> Torr, introducing a gas b consisting of Ar, and sputtering a predetermined target using a mixture of the gases (a, b), so as to form the free magnetization layer under the nonmagnetic layer or forming both of the fixed magnetization layer and the nonmagnetic layer.

Description

4484 3 〇 5. Description of the invention (l) — ----- TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for manufacturing a magnetoresistive film. More specifically, + relates to a method for manufacturing a magnetoresistive effect film that can change the flatness of the build-up screen without deteriorating the crystallinity of the build-up film. In addition, the magnetoresistive effect film formed by the method of the present invention is suitable for a magnetic signal reading head and a magnetic sensor for reading magnetic signals written on a hard disk, a magnetic disk, a magnetic tape, and the like. ..., know-how

With the increase of magnetic recording density, the form of the reading head (reading head) of the magnetic field of the signal recorded by the medium is shifted from the time of the magnetic field change to the inductive magnetic head output. Magnetic resistance type magnetic head. On the magnetoresistive element used in the magnetoresistive element type magnetic head, alloys such as permalloy which show the resistance change with the direction of the element's current flow and the direction of magnetization, such as Permalloy, which is anisotropic magnetoresistance effect (AMR). However, in recent years, it has been found in Fe-Cr multilayer films, Co / Cu multilayer films, etc. that it has a large magnetoresistance effect (GMR) showing a larger rate of change in resistance than AMR. In the structure of such a GMR magnetoresistive element, in addition to the artificial lattice type composed of a structure in which a plurality of ferromagnetic layers are stacked on the surface of the above-mentioned substrate, a non-magnetic layer (spacer) is stacked. A spin valve type having a structure in which a ferromagnetic layer is stacked on top of a non-magnetic layer and an anti-ferromagnetic layer is formed on a surface of the ferromagnetic layer provided last is known. In either type, the GMR series resistors follow the strong magnetic properties of the laminated film

Page 5 4484 3 0 V. Description of the invention (2) The relative angle of the magnetization direction between the layers of the body layer changes due to the turbulent flow of the conduction electrons flowing through the element at the interface between the nonmagnetic layer and the ferromagnetic layer. The direction varies depending on the direction of the spin of the electron and the direction of magnetization of the ferromagnetic layer. It is an interface phenomenon caused by the nature of the spin phase scatter. In a laminated film using this phenomenon, a high resistance is shown when the magnetization directions of the ferromagnetic layers facing each other through the non-magnetic layer are aligned in antiparallel, and a low resistance is shown in a parallel arrangement. Japanese Unexamined Patent Publication No. 4-3583 10 discloses a technology in which a spin-valve type magnetoresistive element in a laminated film showing GMR is applied to a magnetic head for reading, and has been put into practical use in a magnetic recording device for a hard disk. As above. That is, the ferromagnetic layer is called the fixed magnetic exchange layer, which will cause the magnetic fixed magnetization to generate magnetization. Therefore, the magnetization of the layer read from the medium changes, as shown in the figure below. The spin valve is spaced between the non-magnetic layer and. The magnetization is turned on the stacked magnetization layer or anisotropy. Layers and non-magnetic For the external, the direction of the signal magnetic field from the pickup medium is read to read the output layer. The anti-spin layering direction is non-magnetic. The magnetic field of the insulative layer is self-explanatory. The magnetoresistive effect element is basically composed of 4 ferromagnetic layers in a 4-layer structure, and a ferromagnetic layer (generally) of an anti-ferromagnetic layer is provided on the opposite side of the contact surface of one body layer. Intersection is fixed in a single direction. No antiferromagnetic layer is deposited on the external magnetic field, and the magnetization rotation is caused at least through a position in contact with the antiferromagnetic layer. When the magnetic resistance effect element is used as a magnetic head signal, the magnetization direction and free magnetization angle of the ^ fixed magnetization layer that becomes an external magnetic field change, and the magnetic resistance is scattered with the spin phase dependence.

4484 3 0 V. Description of the invention (3) In order to make the spin-valve-type magnetoresistance effect element composed of the above structure effective, the stabilization of the direction of magnetization occurring in the fixed magnetization layer, that is, the control of exchange magnetic anisotropy and Control of spin-dependent scatter becomes important. In order to improve these controllability, it is necessary to improve the crystallinity of the crystalline particles of each layer constituting the laminated film, and to realize a laminated interface with less scattering. In particular, the 'spin-valve type magnetoresistance effect element is as described above, and its characteristics are strongly affected by the state of the laminated interface of the laminated film due to the spin-dependent scattering of the interfacial phenomenon. Therefore, when the roughness of the interface is large, due to the local strong magnetic interaction caused by its unevenness, the anti-parallel arrangement of the magnetization directions that must be achieved is chaotic, the spin phase scattering is not effective, and the change in resistance is not effective. Reduce and suppress the effect of huge magnetoresistance. Therefore, it is strongly desired to improve the flatness of the laminated interface. ^ The object of the present invention is to provide a method for manufacturing a magnetoresistive film, by improving the flatness of the laminated interface without deteriorating the crystallinity of the laminated film, a high-sensitivity reading magnetic signal can be formed. Compared to magnetoresistive effect elements. SUMMARY OF THE INVENTION The first method for manufacturing a magnetoresistive element of the present invention is a magnetoresistive film formed by stacking a free magnetization layer, a nonmagnetic layer, a fixed magnetization layer, and an antiferromagnetic layer on a predetermined substrate in a forward or reverse direction. The manufacturing method is characterized in that at least the substrate is disposed in the film forming chamber, and the degree of vacuum in the film forming chamber is set to about ⑺, ^^ or less, and then at least oxygen is introduced into the film forming chamber. The gas a changes the degree of vacuum in the film forming chamber.

4484 3 〇 5. Description of the invention (4) 'After changing to a fixed pressure of 3 XlO_9Torr or more and 1 xlO-8Torr or less ^ Introducing a gas b made of argon b' Using the gas a and gas b. Gas sputtering A predetermined object forms a &quot; & the &quot; free magnetization layer or the fixed magnetization layer and the nonmagnetic layer under the non-magnetic layer. If the first manufacturing method is used, After reaching the vacuum degree below 1 0-1 QTorr, introduce a given amount of oxygen, and use the present oxygen and argon gas to form a free magnetic layer under the non-magnetic layer + A 卜 Α s, or a fixed magnetization using the sputtering method. Layer and the non-magnetic layer, the good bonding of the three layers will not be impaired, and the surface coarse chain degree of the film will be suppressed. That is, the MR ratio of the magnetoresistive film, which improves the flatness at the interface between the free magnetized layer and the non-magnetic layer or the fixed magnetized layer and the non-magnetic body, is increased. This effect occurs when the degree of vacuum after introducing the oxygen-containing gas a is set to a range of 3 X 10_gTorr or more and 1 X 1 0-8 Tq or less. In addition, in the case where a multi-acoustic film is used in the free magnetized layer, the flatness effect is expected at the entire interface of the multilayer film. 7. The manufacturing method of the second magnetoresistive element of the present invention is about smoothing on a predetermined substrate. A method for manufacturing a magnetoresistive film formed by stacking a free magnetization layer, a nonmagnetic layer, a fixed magnetization layer, and an antiferromagnetic layer in a reverse or reverse direction is characterized in that it has at least: the case where the nonmagnetic layer is stacked on the free magnetization layer After the formation of the free magnetization layer or when the non-magnetic layer is stacked on the fixed magnetization layer After the formation of the fixed magnetization layer, a gas a containing at least oxygen gas is introduced into the film forming chamber, such as the free layer located under the non-magnetic layer The exposed amount of the surface of the magnetized layer or the fixed magnetized layer becomes 6L to 20L (but lL (Langmuir) = l XlCHorrosec), and the surface of the free magnetized layer or the fixed magnetized layer is exposed in an oxygen environment with a predetermined pressure.

4484 3 〇 5. Description of the invention (5) The process of exposure at a fixed time; and by replacing the gas a in the film-forming chamber after the exposure, introducing a gas made of argon, and using the gas b to kill the bell The process of forming the non-magnetic layer on the surface of the free magnetized layer or the fixed magnetized layer after the exposure. According to the second manufacturing method, since the surface of the free magnetized layer or the fixed magnetized layer is formed into a film and exposed to a radon environment, a small amount of the surface is oxidized, and then the freely magnetized layer where the minute portion is oxidized. Or a non-magnetic layer is formed on the surface of the fixed magnetization layer. Due to the deterioration of the flatness of the interface, between the two layers composed of ferromagnetic materials, that is, the local strong magnetic coupling between the free magnetization layer and the fixed magnetization layer, The random magnetization is arranged in antiparallel, but by exposure to a small amount of radon gas environment, part of the oxygen adsorption occurs on the film surface. As a result, the physical interface has the same surface roughness, and the strong magnetic coupling is reduced due to the recession of the interface. The anti-parallel arrangement of stable magnetization is achieved, and the MR ratio of the magnetoresistive effect film is increased. This effect occurs when the exposed amount of the surface of the free magnetized layer or the fixed magnetized layer under the non-magnetic layer is set to a range of 6L or more and 20L or less. In addition, in the case where a multilayer film is used for the free magnetized layer, Among the multilayer films, the layer that forms the interface by contacting the uppermost layer, that is, the non-magnetic layer. If exposed to the oxygen environment, the effect diagram is expected to be briefly explained. FIG. 1 shows the mode of the spin-valve type magnetoresistive effect film of the present invention Figure 2 above shows the magnetoresistive effect used to make the invention as seen from above

4484 3 Ο

V. Description of the invention (6) A plan view of the mode of the sputtering film-forming device used for the film. Figure 3 is a graph showing the relationship between the degree of vacuum ρm when oxygen is introduced and the rate of change in magnetic resistance (MR ratio) of the produced magnetoresistive power film. Fig. 4 shows the relationship between the degree of vacuum ρm when oxygen is introduced and the resistivity, the resistance change amount, and the rate of change in magnetoresistance (mr ratio) of the produced magnetoresistance effect film. Fig. 5 shows the x-rays of the produced magnetoresistance effect film. Diffraction profile ^ Figure 6 is a graph showing the relationship between the amount of oxygen exposure and the produced magnetoresistance efficiency ratio (MR ratio). ^ Figure 7 is a graph showing the relationship between the amount of A gas exposure and the production resistance, the amount of resistance change, and the rate of change in magnetic resistance (MR ratio). Room exhaust devices 2a, 3a, 4a, 4a, '5a, 6a, 7a, 7a' 2b, 3b, 5b, 6b, 7b, 8b Gate valve 3 Pre-processing chamber 4 Transport chamber 5 First film formation chamber 6 Second condition Film chamber 7 Third and fourth film forming chambers 8 Fifth film forming chambers 10 and 11

------ Page 10 4484 3 0 5 'Description of the invention (7) 100 Base 101 Substrate 102 Bottom 1 0 3 Free magnetization layer 104 First ferromagnetic layer 1 0 5 Second ferromagnetic layer 1 0 6 Nonmagnetic Bulk layer 10 7 Fixed magnetization layer 108 Antiferromagnetic layer 1 009 Protective layer Examples of the invention The following examples illustrate the invention in more detail, but the invention is not limited to these examples. (Example 1) In this example, when a spin-valve type magnetoresistive film composed of the structure of FIG. 1 (a) is produced (a case where an antiferromagnetic layer is stacked on a fixed magnetization layer: it is called a top-spin valve type ) 'Only has a free magnetization layer and a non-magnetic layer. After the pressure in the film-forming chamber is reduced to a vacuum of about 10-η Tor r, oxygen (〇2) is introduced to change the pressure in the film-forming chamber to 1 XI. 〇-9T〇rr ~ 5 X 〇-8Tori ·--After the pressure is fixed, argon (Ar) is introduced and formed using the (Ar + 〇2) mixed gas by the storage method. The other layers constituting the spin-valve type magnetoresistive film, that is, the fixed magnetization layer and the antiferromagnetic layer are formed using only argon gas. 4484 3 〇 5. Description of the invention (8) Substrate 101 / bottom layer 10 (Ta film, film thickness 5nm) / first ferromagnetic layer 104 (Ni-Fe film 'film thickness 3nm) / second ferromagnetic layer 1 〇5 (Co film, film thickness Inm) / non-magnetic layer 106 (Cu film, film thickness 2.5 nm) / fixed magnetization layer 107 (C0 film, film thickness 2 nm) / antiferromagnetic layer 108 ( A multilayer structure composed of a Mn-Ir film with a film thickness of 5 nm) / guaranteed layer 109 (Ta film with a film thickness of 5 nm). As the substrate 101, a Si (ioo) single crystal substrate having a thermal oxide film provided on the surface was used. In this example, the substrate 100 is provided with a bottom layer 02 on the substrate 101. Furthermore, in this laminated structure, the first ferromagnetic layer 〇04 and the second ferromagnetic layer 105 constitute a ferromagnetic layer 103. In addition, the film-forming device and device used to make the magnetoresistance-effect film with the above structure are disclosed in Japanese Unexamined Patent Application Publication No. 10-298 * 745. -005). Fig. 2 is a plan view of the film forming apparatus as seen from above. In FIG. 2, 1 is a first loading chamber, 2 is a second loading chamber disposed above the first loading chamber, 3 is a pre-processing chamber, 4 is a transfer chamber, 5 is a first film forming chamber, 6 It is the second film forming chamber, 7 is the third and fourth film forming chambers, 8 is the fifth film forming chamber, and 10 and 11 are substrate moving devices. Also, 2a, 3a, 4a, 4a, 5a, 6a, 7a, 7a, and 8a are exhaust devices that reduce the pressure in each room. Here, the exhaust devices 4a and 43 are disposed below the conveyance chamber 4 (back side of the paper surface). In addition, 2b, 3b, 5b, 6b, 7b, and 8b are gate valves β provided between the respective chambers. Table 1 shows the film forming conditions when the magnetoresistive effect film of this example is manufactured.

3 05. Description of the invention (9) (Table 1) Item setting value &lt; Cleaning process conditions &gt; • Process gas Ar-Argon impurity roll below l (ppb) • Process gas pressure 3 (mTorr) • The temperature control of the substrate holder is at least water-cooled by the substrate holder &lt; common film forming processing conditions &gt; • the film formation method is a parallel plate type 濂 plating method • the temperature control of the substrate holder 20x: (clamp the substrate Holder water-cooled) • Process gas Zhao Ar, (Ar + 〇2) • Impurity concentration in argon l (ppb &gt; His Majesty) • Arrival vacuum degree of each chamber l0-n ~ l0-12Torr (film forming chamber 5 ) Bottom layer 102 and protective layer 109 Ta film (film thickness 5nm) • Target Ta (purity 4N) • Processing gas effect Ar • Processing gas pressure 1 (mTorr) (The first ferromagnetic layer 104 Ni-Fe film in the film forming chamber) (Film thickness 3mn) • Target 78-5wt% Ni-Fe (purity 4N) • Processing gas (Ar + Oa) • Vacuum degree after introduction of 02 P1 lxl〇-9 ~ 5xlO-8Torr * Processing gas pressure 0.75 (mTorr) (Film-forming chamber 7) ① The second ferromagnetic layer 105 Co film (film thickness 1 nm) • Target Co (purity 3N) • Processing gas avoidance (Αγ + 02) • After the bow 1 enters 〇2 The degree of vacuum P1 1 xlO · 9 ~5 χ10_8Τογγ • processing gas pressure 0.6 (mTorr) 11Η11 Page 13448430

V. Description of the Invention (ίο) ② Non-magnetic rhenium layer 106 Cu film (film thickness 2.5nm) • Object Cu (purity 6N) • Processing gas (Αγ + 〇2) * Vacuum degree after introduction of 02: P1 lxl0-9 ~ 5xl0-8Torr • Process gas pressure 0.6 (mTorr) ③ Fixed magnetized layer 107 Co film (film thickness 2mn) • Object Co (purity 3N) • Process gas Ar • Process gas Zhao Moli (film forming chamber 8) 0.6 ( mTorr) Antiferromagnetic layer 108 Mn-It film (film thickness 5nm) • 17at% Mn (purity 3N) + Ir crystal (purity 3N) • Process gas Ar • Process gas pressure 20 (mTorr) Example of a method for manufacturing a magnetoresistive film. The numbers in parentheses indicate their steps. (A1) After the substrate (101 of Fig. 1) is introduced into the first planting room 1 constituting the device of Fig. 2, the exhaust space (not shown) is used to depress the internal space of the first loading chamber 1 from atmospheric pressure to About 1 0-8Torr. (A2) Use the carrier 10 to move the substrate placed inside the first loading chamber 1 from the first loading chamber 1 to the second that the pressure is reduced to about 10'Torr by the exhaust device 2a in advance. Loading room 2. (A3) Use the conveying device 11 to move the substrate disposed inside the second loading chamber 2 to the pre-processing chamber 3 in which the internal space is maintained at an extremely high vacuum of about 10-1 to 10_12 Torr in advance by the exhaust device 3a. Then use

448430 V. Description of the invention (11) Induction-coupling type electric equipment dry-cleaning substrate surface produced by ultra-high purity argon gas under predetermined conditions. (A4) The movement of the substrates from the pre-processing chamber 3 to each of the film-forming chambers 5 to 8 is by using a transporting device (not shown in the figure) built into the transporting chamber 4. Within each of the film forming chambers 5 to 8, 4 spaces are maintained in advance at an extremely high vacuum of about 10-1 to 10-2 Torr. In addition, the vacuum degree of the transfer room 4 also reached about 10-MT〇rr, and the vacuum degree will not rise to 1. 〇-i〇Torr or more when the use of the built-in transfer device operation (in the special wish flat 10-296666 disclosed in the carrier of ultra-high vacuum). A machine (A5) forms a Ta film (5 nm) as a bottom layer 102 on a substrate 101 as a substrate 100 of this example. The steps are as shown in the following (person 5_4). (A 5 -1) Open the gate valve 3 b 'Remove the substrate from the pre-processing chamber 3 using the handling device built in the removal chamber 4' After closing 3b, open 5b to move to膜 室 5。 Membrane chamber 5. Then, the gate valve 5b is closed. In the state where the substrate is set, the vacuum degree of the film forming chamber 5 is also maintained at an extremely high vacuum of about 10-n to 10-2 Torr. (A5-2) Secondly, the ultra-high purity argon gas is introduced into the film forming chamber 5 until the processing gas pressure (Table 丨) becomes the film forming conditions. (A5-3) After a predetermined power is applied to the yin steady, a Ta object is splashed. First, after performing a pre-sputter for a fixed time, a Ta film having a thickness of 5 pm was formed on the substrate by opening a shutter covering the surface of the substrate at a predetermined time. The thickness of the Ta film is controlled by closing the shutter after a predetermined time has elapsed. (A5-4) Secondly, the power is reduced, and after the discharge is completed, the supply of argon gas is stopped to exhaust the internal space of the film forming chamber 5 to about 10-n Torr.

苐 Page 15 4484 3 〇 5. Description of the invention (12) (Α6) Secondly, a Ni ~ Fe film (3nm) was formed on the Ta film (bottom layer) 102 as the first ferromagnetic layer 104. The steps are shown in the following steps (A6-5). 1 (A6-1) After the Ta film is formed, the gate valve 5b is opened, and the substrate is taken out of the film forming chamber 5 using the conveying device hidden in the conveying chamber 4. After 5b is closed, 6b is opened to move to the film forming chamber 6. Then, close the gate valve 6 b. In the state where the substrate is installed, the vacuum degree of the film forming chamber 6 is kept extremely high. ’, (A6-2) Adjust the oxygen bow into the inner space of the film forming chamber 6 through a variable leakage valve (not shown), and adjust it to a predetermined vacuum degree? 1 (1 &gt; &lt; 1〇-9 ~ 5 &gt; &lt;: fixed pressure of 10-8 Torr). (A6-3) Secondly, ultra-high purity argon gas is introduced into the inner space of the film forming chamber 6 to the pressure of the processing gas that becomes the film forming condition (as shown in Table n. Therefore, the vacuum degree of (Ar + 〇2) becomes the pressure of the processing gas (A6-4) After applying predetermined power to the cathode, sputtering (NiFe) is performed. First, after pre-sputtering for a fixed period of time, a shutter covering the surface of the substrate is opened at the predetermined time to form a Ta film. N1 -Fe film with a thickness of 3nm. The thickness of the n film is controlled by closing the shutter after a predetermined period of time. Sheet (A6-5) Secondly, "reducing the power" to stop the discharge of argon and oxygen , Exhaust the internal space of the film formation chamber 6 to about 10-Torr. (A7) Secondly, a Co film (Inm) is formed on Ni ~ Fe (first ferromagnetic layer) ι04, As the second ferromagnetic layer 105, a Cu film was formed thereon.

Page 16 4484 V. Description of the invention (13) (2 * 5nm) 'as a non-magnetic layer 106' and a Co film (2nm) 'is formed thereon as a fixed magnetization layer 107. The steps are shown in (A7-I) and (A 7-5) below. (As soon as A 7 forms the Ni-Fe film 104, the gate valve 6b is opened, the substrate is taken out of the film forming chamber 6 using the conveying device built in the conveying chamber 4, and after closing 6b, the opening 7b is opened to move to Membrane chamber 7. Then, 'the gate valve 7b is closed. In the state where the substrate is installed', the vacuum degree of the film forming chamber 7 is maintained at about 10-Π ~ l0-〗 2Torr pole 1¾ vacuum. (A7-2) Via variable The leak valve (not shown in the figure) introduces oxygen into the internal space of the film-forming chamber 6 to adjust to a predetermined vacuum degree Pl (fixed pressure of 1 X 10- 9 to 5 X 10-8 Torr). (Α7-3) Second 'Introduce ultra-high purity argon gas into the film-forming chamber 7 until the process gas pressure (Table 1) becomes the film-forming conditions. Therefore, the vacuum degree of (Ar +02) becomes the process gas pressure a (A7-4-1) After applying predetermined power to the two cathodes, sputter the target of C0 and Cu. First, after pre-sputtering for a fixed time, open the shutter covering the surface of the substrate on the Ni_Fe film at a predetermined time. A Co film (second ferromagnetic layer) having a thickness of 1 nm was formed. The thickness of the C film was controlled by closing the shutter after passing through a predetermined N ′ interval. U7-4 -2) After the substrate having formed the co film (second ferromagnetic layer) 105 has been moved to the cu target side by using the transporting device built in the film forming chamber 7, the shutter covering the substrate surface is opened at a predetermined time. A Cu film (non-magnetic layer) 106 having a thickness of 2'5 nm was formed on the Co film 105. Control the CU membrane by closing the shutter after a set time

Of thickness.

Page 17 4484 30 Fifth invention description (14) ~-<^ A7-4-3) Secondly, the supply of oxygen introduced into the film forming chamber 7 is stopped, and the vacuum degree changed to argon becomes the processing gas pressure. The substrate formed with the Cu film (non-magnetic layer) 1 06 is moved to the target side by using the transporting device built in the film forming chamber 7 'by opening the shutter covering the substrate surface on the Cu film 106 at a predetermined time. A Co film (fixed magnetization layer) 107 having a thickness of 2 nni was formed. The film thickness is controlled by closing the shutter after a predetermined time has elapsed. Production (A7-5) is followed by reducing the power so that after the discharge is completed, the supply of argon is stopped 'and the internal space of the film forming chamber 7 is exhausted to about 10-nTorr. (A8) Next, a Mn_ir film (5 nm) was formed on Co 臈 (fixed magnetization layer) 107 as an antiferromagnetic body 108. The steps are shown in (ah), (a8 4). (Α8-1) Open the idle valve 7b, and take out the substrate from the film formation to 7 by using the transporting device built in the transport chamber 4. 'Close 7b' and open 8b to move to the film formation chamber 8. Then, when the gate valve 8b is closed, the state of the substrate is set, and the vacuum degree of the film formation to 8 is maintained at an extremely high vacuum of about 10-11 to 10-2 Torr. (A8-2) Secondly, ultra-high purity argon gas is introduced into the film forming chamber 8 until the pressure of the process gas becomes the film forming conditions (Table 1). (A8-3) After a predetermined power is applied to the cathode, a Mn_Ir object is sputtered. First, after performing pre-sputtering for a fixed time, a Mn-Ir film 108 having a thickness of 5 nm was formed on a Co film (fixed magnetization layer) 107 by opening a shutter covering the surface of the substrate at a predetermined time. The thickness of the Mn-Ir film is controlled by closing the shutter after a predetermined time has elapsed. (A8-4) Secondly, after the electric power is reduced to stop the discharge, the supply of argon gas is stopped, and the internal space of the film forming chamber 8 is exhausted to about ι0-ητου.

5. Description of the invention (15) (A9) Secondly, a Ta film (5 nm) is formed on the Mn-Ir film (antiferromagnetic layer) 108 as a protective layer 109. The film-forming step at that time is the same as that described in (A5) above except that the substrate is moved from the film-forming chamber 8 to the film-forming chamber 5. (A10) Finally, the substrate on which the protective layer (Ta film) 10 is formed is sequentially moved to the film formation chamber 5-pre-processing chamber 3-second loading chamber 2-first loading chamber 1 'self-manufacturing Take out the magnetoresistive film with the laminated structure of this example from the device. The magnetoresistance effect film of this example was formed by the above processes (A1) to (A10). At that time, in the above-mentioned processes (A6) and (A7), by changing the vacuum degree Pl (1 Xl0-9 ~ 5 Xl0-8Torr fixed pressure) when introducing 〇2, a magnetoresistive film with different pi was made ^ Hereinafter, the magnetoresistive efficacy film produced in this example is referred to as test piece α 0 (Comparative Example 1). In this example, the processes (A6) and (Α7) in the process of Example 1 do not introduce oxygen and are used only. The argon gas, that is, the first ferromagnetic layer 102 / the second ferromagnetic layer 103 / non-magnetic layer 104 was formed by replacing the (Ar + 〇2) mixed gas 氩 with argon. The structure of the magnetoresistive film is different from that of the first embodiment. The rest is the same as that of the first embodiment. Hereinafter, the magnetoresistive efficacy film produced in this example will be referred to as a comparative test piece 1 d (Comparative Example 2). In this example, when the magnetoresistive efficacy film is produced in the same manner as in Comparative Example 1, each film constituting the manufacturing device will be formed. The arrival vacuum degree p2 in the room and the conveying room was set to a fixed pressure in the range of 10-iDT0rr to 10-7Torr, and a magnetoresistive effect film composed of the same laminated structure as in Example 1 was produced. Other set to and

Page 19 4484 30 V. Description of the invention (16) The same as in Comparative Example 1. Hereinafter, the magnetoresistive efficacy film produced in this example is referred to as Comparative Test Piece / 52. Fig. 3 is a graph showing the relationship between the process (A6) in the embodiment] and the degree of vacuum P1 when oxygen is introduced and the magnetoresistance change rate (MR ratio) of the produced magnetoresistance effect film. The result is indicated by _ mark. In Fig. 3, for comparison, the result of the comparison test piece is 1 (◦ symbol) and the result of the comparison test piece ^ 2 (◊ symbol) is also shown. The horizontal axis at this time indicates the reached vacuum degree P2 in each film forming chamber and the conveying chamber. Fig. 4 is a graph showing the relationship between the degree of vacuum pi when oxygen is introduced and the resistivity, resistance change amount, and magnetoresistance change rate (MR ratio) of the produced magnetoresistance effect film. However, the ratio shown in FIG. 4 is the same as that in FIG. 3. Figure 5 shows the X-ray diffraction profile of the fabricated magnetoresistive film. The following experimental results were obtained from FIG. 3. (a) In the comparative test piece 2 (0 mark) equivalent to the conventional example, as the vacuum degree P2 of the film forming chamber and the like decreases, the MR ratio shows an increasing tendency, and p2 is set to about 10-1] Torr Comparing test piece 01 (0 mark), a dragon ratio of about 10% is obtained. (B) In the test piece of the present invention, when the vacuum degree ρ 丨 when oxygen is introduced becomes higher, the MR ratio increases in a certain range of P1. . (c) That is, in the manufacturing conditions of the test piece α, a sputtering process is used to form a free magnetized layer (first ferromagnetic layer, second ferromagnetic layer) and a non-magnetic layer into a film. The vacuum when introducing oxygen is used. When the degree P1 is in a fixed dust force range above 3 X 丨 〇-9 Torr and under 1X108 Torr &amp;, an excellent value having a maximum MR ratio (compared to the test piece 1) exceeding the conventional example can be obtained. The MR ratio is compared to the magnetoresistive effect element.

Page 20 4484 3 〇 5. Description of the invention (17) The following points will be understood from FIG. 4 below. The resistivity p s increases only when P1 is 5 X 1 0-8 Torr *, and it hardly changes in other P1 regions, which is about the same value as the result (zero symbol) of the point 1 of the comparison test piece. In addition, the resistance change Ap, which is in the range of 3 X 10_9 Torr to 1 X 1 0-8 Torr, is larger than the result (0 mark) of the comparison sample Lu 1 and shows a maximum value at 5 X 1 (Mor r. That is, It can be seen from Fig. 3 that the MR ratio increases with an increase in Δp. Furthermore, the result of investigating the crystal structure of the film constituting the test piece with P1 changed by the X-ray diffraction method is shown in Fig. 5 at 26 = 52 ( deg) The peak intensity of fcc (iii) observed near P1 tends to decrease when P1 is 3 x 10_9 Torr or more. However, the degree of vacuum below this value shows and compares the peak intensity of the specimen with about 1 and is not found. 38 ° ， The deterioration of the crystal caused by the addition of radon. Also, the surface roughness of the test piece (Pi X 10-9Torr) produced by AFM evaluation and the comparison of the film thickness of the test piece was 1. The latter is "78." From this result, we know that

Take in an appropriate amount of oxygen to reduce the surface roughness of the film. This implies that the flatness of the interface of the laminated structure is improved. Therefore, at least when the first ferromagnetic layer and the second magnetic layer are formed, the degree of vacuum is reduced. 1 becomes located on the fx layer, layer 2 and 2 '? ° &quot; The following amounts of oxygen and argon form each

The SI plane of the interface of the laminated structure can be obtained. In addition, in this example, the method of applying the magnetic resistance of the laminated structure of 1 (a) of the present invention is described in detail.

4484 3 〇 V. Description of the invention (18) In the case of an antiferromagnetic layer: top spin valve type), it is confirmed that the layer structure is opposite, that is, the layer structure shown in Fig. 1 (b) (in antiferromagnetism) In the case where a fixed magnetization layer is deposited on the body layer: bottom spin valve type), the above-mentioned effect can also be obtained. However, in the case where the laminated structure of FIG. 1 (b) is adopted, for example, a (Ni-Fe) film deposited on Ta 臈 is suitable for the bottom layer 102. (Example 2) In this example, the following two points were changed, and the same lamination structure as in Example 1 was produced using the film-forming apparatus of FIG. 2 in the same manner as in Example 1 (Figure 丨 (a): Top Spin Valve Type) ) Of the magnetoresistive effect film, ① In the process (6) and (7) of the process of Example 1, no oxygen is introduced and only argon is used, that is, argon is used instead of (A r + 〇2) mixed gas, A first ferromagnetic layer (Ni-Fe film) 104 / second ferromagnetic layer (Co film) 105 / nonmagnetic layer (Cu film) 106 is formed. ② The top and bottom interfaces of the non-magnetic layer (CU film) 106 constituting the laminated structure, that is, the surface of the second ferromagnetic layer ((; 〇 film) 105) and the non-magnetic layer (Cu film) constituting the free magnetization layer The surface of 106 or one surface is exposed to a predetermined oxygen environment. At that time, the exposure amount should be changed in the range of 1L to 200L. Here, 'lL = lxlO-6Torr / sec (L is Langmuir unit). Others A magnetoresistive effect film was produced in the same manner as in Example 1. Table 2 shows the film formation conditions when the magnetoresistance effect film of this example was produced.

Page 22 4484 3 (Table 2) V. Description of the invention (19) Item setting value &lt; Cleaning process conditions &gt; • Process gas Ar • Impurity concentration of argon gas below l (ppb) • Process gas pressure 3 (mTorr) • The temperature of the substrate holder is controlled by at least water cooling of the substrate holder <common processing conditions> • film formation method parallel flat-type sputtering method • substrate surface holding temperature 20 ° C (holding the substrate (Water cooling of the device) • Ar, (Ar + 02) processing gas • Impurity concentration in argon gas below l (ppb) • The vacuum degree of each chamber is 10-^-ΙΟ ^ Τγγ (film forming chamber 5) Bottom layer 102 and Protective layer 109 Ta film (film thickness 5mn) • Target Ta (purity 4N) • Processing gas Ar • Processing gas pressure l (mTorr) (film forming chamber 6) First ferromagnetic hafnium layer 104 Ni-Fe film (film thickness 3nm ) • Target 78.5wt ° / 〇Ni-Fe (purity 4N) • Processing gas Zhao Ar • Processing gas pressure 0.75 (mTorr) (film forming chamber 7) ①Second ferromagnetic layer 105 Co film (film thickness lrnn) • Target Co (purity 3N) • Processing gas Ar * Processing gas pressure 0.6 (mTorr)

Page 23

4484 3 C V. Description of the invention (20) ① 'Gas exposure (Co film) * Process gas • Vacuum degree of radon exposure P3 • Oxygen exposure time • Radon exposure ② Non-magnetic layer 106 • Object • Process gas Zhao * Process gas chain pressure ② 'Gas exposure (CU film) * Process gas • Vacuum degree of radon exposure P3 • Radon exposure time * Oxygen exposure amount ③ Fixed magnetization layer 107 • Object • Processing Gas Zhao • Processing gas pressure (film-forming chamber 8) Anti-ferromagnetic layer 108 • Object • Processing gas forging • Processing gas pressure 〇2

2 xl 0_9 ~ 3.5 xl 0'7T orr 10 minutes 1L-200L

Cu film (film thickness 2.5nm)

Cu (purity 6N)

Ar 0.6 (mTorr) 〇2 2xl〇-9 ~ 3.5xl〇-7Torr 10 minutes 1L-200L Co film (film thickness 2nm)

Co (purity 3N)

Ar 0.6 (mTorr)

Mn- Ir film (film thickness 5nm) 17at% Ir · Μη (purity 3N) + Ir crystal (purity 3N)

Ar 2Q (mTorr) _ The following describes the manufacturing method of the magnetoresistive effect film in this example. The numbers in parentheses indicate their steps. (B1) ~ (B5) The process (A1) ~ (A5) of Example 1 is carried out-

Page 24 4484 3 V. Description of the invention (21) Process, a bottom layer 102 and a Ta film (5 ηπ) are formed on a predetermined substrate 101 as a substrate 100. (B6) Next, a Ni-Fe film (3 nm) was formed on the Ta film (underlayer) 102 as the first ferromagnetic layer 104. The steps are shown in (B6-1) to (B6-4) below. (B6-1) After the Ta film 102 is formed, the gate valve 5b is opened, and the substrate is taken out of the film forming chamber 5 using the conveying device built in the conveying chamber 4. After closing 5b, 6b 'is opened to move to the film forming chamber 6. Then, the gate valve 6b is closed. In the state where the substrate is installed, the vacuum degree of the film forming chamber 6 is maintained at an extremely high vacuum of about 1 to 1 〇_] 2Torr. (B6-2) The ultra-high purity argon gas is introduced into the film forming chamber 6 until the pressure of the processing gas (Table 2) becomes a film forming condition. (B6-3) After applying a predetermined power to the cathode, a (Ni_Fe) object is sputtered. First, after pre-sputtering for a fixed period of time, by opening a shutter covering the surface of the substrate at a predetermined time, a N1 -Fe film having a thickness of 3 nm was formed on the Ta film. The thickness of the N 丨 film is controlled by closing the shutter after a predetermined time has elapsed. Bu (^ 6: 4) Secondly, “reducing the power” to stop the supply of argon and oxygen after the discharge is completed, and exhaust the internal space of the film forming chamber 6 to about 10_u T〇rr

stop. W (ΒΉ) Secondly, a film (1ηπ) was formed on Ni_Fe (first ferromagnetic layer) 104, and a second ferromagnetic layer 105 was formed thereon, and a hafnium film (2_5nn0) was formed thereon as a nonmagnetic layer 1 〇6 'A film (2nm) is formed thereon as the fixed magnetization layer 107. The procedure is as follows (B7_ι) ~

P.25 4484 5. Description of the invention (22 ^-1 '(B7-5). 1) After forming the Ni-Fe film 104, the gate valve 6b is opened, and the transportation device in the 4th transportation room &amp; The film-forming chamber 6 takes out the substrate, and after closing 6b, it opens 7b 'and moves to the film-forming chamber 7 = Then, the gate valve 7b is closed. In the state where the substrate is provided, the vacuum degree of the film forming chamber 7 is maintained at an extremely high vacuum of about 10-n to 10] 2 Torr. (B7-2) The ultra-high-purity argon gas is introduced into the film forming chamber 7 until the pressure of the processing gas (Table 2) becomes a film forming condition. ) After applying a predetermined power to the cathode, the target is sputtered. First, after pre-sputtering for a fixed time, a shutter having a thickness of 1 nm (a second ferromagnetic layer) 105 is formed on the Ni_Fe film 104 by opening a shutter covering the surface of the substrate at a predetermined time. The thickness of the Co film is controlled by closing the shutter after a predetermined time has elapsed. (A7-4-2) After the Co film (second ferromagnetic layer) ι was formed, the discharge was stopped and the argon gas was cut off. Then, the oxygen gas is introduced into the inner space of the film forming chamber 7 through a variable leak valve (not shown in the figure), and adjusted to a predetermined vacuum degree p3 (a fixed pressure of 2 x 10-9 to 3.5 X 10_7 Torr). Then, the surface of the Co film 105 was exposed to an oxygen environment for a fixed time (10 minutes) as it is. With this operation, the exposure amount of the Co film 105 is changed in a range of 1L to 200L. (B7-4-3) After a fixed time has elapsed, the oxygen is cut off, and the transporting device built in the Li film forming chamber 7 moves the substrate on which the Co film 105 is formed to the Cu target side. Then, argon gas is further introduced into the inner space of the film forming chamber 7, and a predetermined power is applied to the cathode to sputter the Cu target. A 2.5 nm-thick Cu film was formed on the Co film 105 by opening the shutter covering the surface of the substrate at a predetermined time.

Page 26 4484 30 V. Description of the invention (23) (non-magnetic layer) 106. The thickness of the Cu film is controlled by closing the shutter after a predetermined time has elapsed. (B7-4-4) After the Cu film (non-magnetic layer) 106 is formed, the discharge is stopped and the argon gas is cut off. Then, a variable leak valve (not shown in the figure) is used to introduce oxygen into the internal space of the film forming chamber 7 and adjust it to a predetermined vacuum degree P3 (2 X 10-9 to 3.5 parent 10-7 but 0): 1 ' Fixed pressure). Then, the surface of the Cu film 106 was exposed to an oxygen environment for a fixed time (10 minutes) as it is. With this operation, the exposure amount of the Cu film 106 is changed in a range of 1L to 200L. (B7-4-5) After a fixed period of time, cut off the oxygen, and use the transporting device built in the film-forming chamber 7 to make the substrate on which the Cu film (non-magnetic layer) 106 is formed, and then move it to the Co object side. The internal space of the membrane chamber 7 is further filled with argon gas, and a predetermined power is applied to the cathode to sputter the Co object. By opening the shutter covering the surface of the substrate at a predetermined time, a Co film (fixed magnetization layer) 107 having a thickness of 2 nm was formed on the Cu film 106. The thickness of the Co film is controlled by closing the shutter after a predetermined time has elapsed. (B7-5) Secondly, the power is reduced, and after the discharge is completed, the supply of argon gas is stopped, and the internal space of the film forming chamber 7 is exhausted to about 10-UTorr. (B8) ~ (B9) The same process as in Example 1 (A8MA9) was performed-the same process was performed on the Co film (fixed magnetization layer) 107 in order to form an Mn-Ir film (5 nm) as the antiferromagnetic layer 108. A Ta film (5 nm) as the protective layer 109. (B10) The same process as in Example 1 (A10) is performed. The same process is performed, and the magnetoresistive film having the laminated structure of this example is taken out of the self-made device. The magnetoresistive effect film of this example was formed by the above processes (B1) to (B10). At that time, the Cu film (non-magnetic layer) was changed by the above-mentioned process (B7).

Page 27 4484 3 〇 5 Description of the invention (24) 106 Upper and lower interfaces, namely Co film (second ferromagnetic layer) 105 and Cu film (non-magnetic layer) Each surface of the vacuum when exposed to an oxygen environment Degree p3 (fixed pressure of 2 X 10- 9 to 3.5 X 10 7 Torr), made of magnetoresistive films with different exposure. Hereinafter, a magnetoresistance effect film made by exposing the upper and lower interfaces of a Cu film (non-magnetic layer) 106 to an oxygen environment is referred to as a test piece 1. (Example 3) In this example, in the process (B7) of Example 2, the non-magnetic layer (cu film) 106 is not placed above and below the interface, that is, the second ferromagnetic layer (co film) 105 and non-magnetic Each surface of the bulk layer (Cu film) 106 was exposed to an oxygen environment, and only the surface of the second ferromagnetic layer (Co film) 105 was exposed to an oxygen environment to make a magnetoresistive effect film different from that in Example 2. The rest is the same as that of the second embodiment. Hereinafter, the magnetoresistive efficacy film produced by exposing only the surface of the second ferromagnetic layer (co film) 105 to an oxygen environment is referred to as a test piece 2. (Example 4) In this example, in the process (B7) of Example 2, 'the non-magnetic layer (Cu film) 106 is not provided above and below the interface, that is, the second ferromagnetic layer ((: 0 film) 105 and non- Each surface of the magnetic layer (Cu film) 106 was exposed to an oxygen environment, and only the surface of the non-magnetic layer (Cu film) 106 was exposed to an oxygen environment. A magnetoresistive effect film was produced differently from Example 2. Others and Example 2 Same. Hereinafter, the magnetoresistive film made by exposing only the surface of the non-magnetic layer (Cu film) 106 to an oxygen environment is called test piece r 3. Figure 6 shows the second strong magnetism in the above process (B7). The relationship between the exposure amount of the surface of the bulk layer ((: 0 film) 105 and non-magnetic layer (0 11 film) 10 when exposed to an oxygen environment and the MR ratio of the magnetoresistive film produced. Figure 6,_

4484 30.5. Description of the invention (25) The symbol indicates that the upper and lower interfaces of the second ferromagnetic layer (Co film) are exposed to oxygen sample 7 1 (denoted as Co &amp; Cu), and the △ symbol indicates that it is only the second strongest. The surface of the magnetic layer (Co layer) is exposed to the oxygen test piece γ2 (denoted as Co). Where mouth 1 has shouted that only the surface of the non-magnetic layer (Cu layer) is exposed to the oxygen test piece r 3 (denoted as Cu). Happening. In addition, FIG. 6 also shows the results of the comparative test piece Lu 1 (zero mark) produced in Comparative Example 1 (Mil? Ratio = about 10%). Fig. 7 is a graph showing the relationship between the amount of oxygen exposure and the resistivity, resistance change, and magnetoresistance change rate (MR ratio) of the fabricated magnetoresistance effect film. However, the MR ratio shown in Fig. 7 is the same as that of Fig. 6. The following experimental results are obtained from FIG. 6. (1) When the test specimen T1 and test specimen T2 are in the range of 6L or more and 20L or less, it is possible to produce an excellent mr ratio that exceeds the maximum value of the service ratio in the conventional example (in the case of the test piece / 51). Especially for the magnetoresistive film D, when the oxygen exposure exceeds 20L, the MR ratio decreases significantly. (2) The 'test piece 73 is hardly affected by the increase in the amount of oxygen exposure, and at any oxygen exposure amount, it is approximately equal to the maximum value of the MR ratio | ^ ratio. From the results (1) and (2) above, it is known that the MR ratio can be obtained by exposing at least the surface of the second ferromagnetic layer (Co film) 103 to an oxygen environment and limiting the exposure amount to a predetermined range. Increase effect. On the other hand, the following matters are understood from FIG. 7. The resistivity p s increases sharply when only the Co film is exposed and when both sides (both the c0 film and the Cu film) are exposed. In the case of only Cu film exposure, ps is almost constant regardless of the amount of exposure ^

4484 3ϋ Five 'invention description (26)

However, changes in resistance (both sides of the Co film and the Cu film) increase. Only the Cu film becomes constant. Amount △! 〇 In the case where only the C0 film is exposed and the case where both sides are exposed, the case where the exposure amount is sharply exceeded when the exposure amount exceeds 20 l 'Λρ has almost nothing to do with the exposure amount, so the test piece γ 7, 丨, 尨 a π a and test piece 72 were sharply reduced when the exposure amount exceeded 20L, and the effect of oxygen exposure was greater than that of the Cu film. The reason why push test 7: 7 2 can obtain the MR ratio exceeding the conventional example (in the case of test piece M) when the oxygen exposure amount is in the range of 6L to 20L is as follows. + Between two layers made of a ferromagnetic body ', that is, the local strong magnetic coupling effect between the free magnetization layer and the fixed magnetization layer is due to the unevenness at the interface f 5 local magnetic poles. By exposing the interface to oxygen, the uneven portion absorbs oxygen atoms, and although there is no physical interface flattening effect, it suppresses local magnetic pole induction and has the effect of reducing local strong magnetic coupling. In addition, in this example, the application of the manufacturing method of the present invention to the magnetoresistance effect composed of the laminated structure of FIG. 1 (a) is described in detail (a case where an antiferromagnetic layer is stacked on a fixed magnetization layer: top spin valve Type), but it was confirmed that the above-mentioned effect can also be obtained in the layered structure shown in FIG. 1 (b) where the layer structure is reversed (the case where a solid magnetized layer is deposited on the antiferromagnetic layer: bottom spin valve type). That is, at the bottom spin valve type, at least the interface between the fixed magnetized layer 107 and the non-magnetic layer should be exposed to oxygen, that is, the surface of the fixed magnetized layer 107. However, in the case where the laminated structure of Fig. 1 (b) is adopted, for example, a (Ni-Fe) film deposited on a Ta film is suitably used for the bottom layer 102.

Page 30 ^ 434 3 c V. Description of the invention (27) Industrial applicability As shown above, if the first manufacturing method of the present invention is used, at least the first ferromagnetic layer and the second ferromagnetic layer When forming a non-magnetic layer, each layer is formed by using oxygen and argon in an amount of 3 xlO_9Torr or more and 1 XlO ^ Torr or less in vacuum degree P1. The interface of the laminated structure is improved while maintaining the good crystallinity of the film. Flatness, a magnetoresistance effect film having a higher MR ratio than conventional can be obtained. In addition, if the second manufacturing method of the present invention is used, at least the surface of the second ferromagnetic layer constituting the free magnetization layer is exposed to an oxygen environment, and the exposure amount is set to a range of 6L or more and 20L or less. Knowing the high MR ratio of the magnetoresistive effect film. By the method of manufacturing the magnetoresistive effect film of the present invention, it is possible to stably manufacture an MR head capable of adapting to a higher recording density.

Claims (1)

4484 30.6. Application for Patent Scope 1. A method for manufacturing a magnetoresistive film, which is formed by stacking a free magnetized layer, a non-magnetic layer, a fixed magnetized layer, and an anti-strength layer in a forward or reverse direction on an existing substrate. It is formed by a magnetic layer, and is characterized in that at least the substrate is disposed in a film forming chamber, and the degree of vacuum in the film forming chamber is set to about 10-HT0rr or less, and at least After the gas a containing oxygen, change the vacuum degree in the film forming chamber to a fixed pressure of 3X l0-9 Torr or more and 1 x 10-8 Torr or less, and then introduce a gas b made of argon, and use the carcass a and gas. The process of sputtering a predetermined object of the mixed gas of b to form the free magnetization layer or the fixed magnetization layer and the nonmagnetic layer under the nonmagnetic layer. 2 · —A method for manufacturing a magnetoresistive effect film, which is formed by stacking a free magnetization layer, a nonmagnetic layer, a fixed magnetization layer, and an antiferromagnetic layer on a predetermined substrate in a forward or reverse direction. At least: when the non-magnetic layer is stacked on the free magnetization layer, after forming the free magnetization layer, or when the non-magnetic layer is stacked on the fixed magnetization layer, after forming the fixed magnetization layer, introduce at least Oxygen-containing gas a 'If the exposed amount of the surface of the free magnetization layer or the fixed magnetization layer below the non-magnetic layer becomes 6L or more and 20L or less, and 1L = 1 X l (T6Torrosec, at a predetermined pressure) A process for exposing the free magnetization layer or the surface of the fixed magnetization layer for a predetermined period of time in an oxygen environment; and by replacing the gas a in the film-forming chamber after the exposure, introduction of HM IIMI, page 32, 4484 3 Ο Page 33