Patent Application
20110253037
The present invention relates to a vacuum heating and cooling apparatus which rapidly heats and cools a substrate for a semiconductor device, an electronic device, a magnetic device, a display device, and the like in vacuum.
A tunnel magnetoresistance element having an MgO tunnel barrier layer, used as a sensor element of a magnetic random access memory (MRAM) and a magnetic head has a structure of laminating a plurality of metal films (magnetic film and non-magnetic film) and insulating films (such as MgO tunnel barrier layer). That type of magnetoresistance element is deposited by sputtering method excellent in productivity, followed by heat treatment in a separate apparatus (magnetic field heat treatment furnace) while applying high magnetic field of 1 Tesla or more, (refer to Non-Patent Document 1).
The method of forming the MgO tunnel barrier layer is disclosed as, for example, the method of directly performing sputter deposition of a MgO target by the RF sputtering method, (refer to Patent Document 1), the method of forming a metal Mg film, and then forming a metal Mg film in oxygen atmosphere by the reactive sputtering method, followed by applying oxidation treatment, (refer to Patent Document 2), the method of forming a metal Mg film, and then applying oxidation treatment, followed by once again forming a metal Mg film, (refer to Patent Document 3), and the method of forming a metal Mg film, and then applying oxidation treatment, followed by applying heat treatment, further by again forming a metal Mg, and finally applying oxidation treatment, (refer to Patent Document 4).
There is a method of forming the MgO tunnel barrier layer having further high quality, as disclosed in Non-Patent Document 2, which method enhances crystallization of MgO film by, immediately after applying direct sputter deposition of MgO target by the RF sputtering method, heating the film by irradiating the substrate with infrared light while holding the substrate in a vacuum.
When, as disclosed in Patent Document 4 and Non-Patent Document 2, the heat treatment is applied between depositions, mass production process needs to rapidly cool the substrate after heated down to a temperature suitable for the next deposition (such as room temperature) or in order to stop alteration of film quality such as crystal growth during heating.
Regarding the method of rapidly heating the substrate in a vacuum, the process of forming a semiconductor element includes, as disclosed in Patent Document 5, a method in which the vacuum chamber has a window allowing the heating light to pass therethrough via a vacuum-seal member such as O-ring, thus heating the substrate held in the vacuum chamber by a radiation energy source such as infrared lamp being positioned at the atmosphere side to emit the heating light.
As the method of rapidly cooling the heated substrate, there is a method, as disclosed in Patent Document 6, of cooling the substrate by transferring the substrate into a chamber adjacent to the heating chamber and being thermally isolated from the heating chamber. According to the cooling method, rapid cooling of the substrate is performed by thermal conduction by placing the substrate directly on a cooled substrate-supporting table. As the method of cooling the substrate while leaving the substrate in the heating chamber, not transferring it to the cooling chamber, there is, as disclosed in Patent Document 7, a method in which a cooled gas is introduced into the heating chamber to conduct cooling utilizing the convection of gas. For the method, there is disclosed a technique of increasing the cooling efficiency by inserting a shutter plate to shield the remaining heat of radiation energy source between the radiation energy source and the substrate after completing the heating step.
For the method of further increasing the cooling efficiency, there is a method of applying a heat treatment apparatus, as disclosed in Patent Document 8, which positions a fixed cooling source and a movable cooling plate within the same space as the heating chamber. According to the method disclosed in Patent Document 8, the movable cooling plate is cooled while being positioned to contact with the cooling source during substrate-heating step. And then after completing the substrate-heating step, the movable cooling plate is brought to apart from the cooling source and into contact with the substrate, thus cooling the substrate utilizing the thermal conduction between the substrate and the movable cooling plate.
There is another method, as disclosed in Patent Document 9, of cooling the substrate within the same space as the heating chamber, in which the movable cooling source is brought into contact with the substrate-supporting table containing a heating resistor, thus indirectly cooling the substrate. Furthermore, Patent Documents 10 and 11 disclose similar methods of heating and cooling the substrate by bringing the substrate-supporting table into contact with the heating source and the cooling source.
According to Patent Document 11, the substrate-supporting table itself has the heating and cooling function, and has the electrostatic-attraction function in order to increase the heating and cooling efficiency, and further the substrate-supporting table provided with the electrostatic-attraction function has grooves on a surface contacting with the rear surface of the substrate, to which grooves a gas is introduced to enhance the heat exchange.
As an example of arranging separate heating source and cooling source in a single vacuum chamber to directly heat and cool only the substrate, Patent Document 12 discloses an example of the structure of a load-lock chamber of sputtering apparatus having a mechanism of heating the substrate using the heating light of a lamp heater and having a mechanism of cooling the substrate by bringing the substrate into contact with the substrate-supporting table which is cooled by electrostatic-attraction. According to the example, successive heating and cooling is not the object because the load-lock chamber has both functions. However, heating and cooling are given during evacuation and venting of the load-lock chamber, which shortens the treatment time of sputtering deposition accompanied with the substrate heating.
Execution of both heating step and cooling step in the same vacuum chamber raises a problem of increase in the temperature of members in the chamber with increase in the number of treating substrates owing to the irradiation of heating light to the member in the chamber at every heating step, thus deteriorating the reproducibility of heating step and cooling step.
The present invention has been made in view of the above problem, and an object thereof is to provide a vacuum heating and cooling apparatus which can conduct rapid heating and rapid cooling of substrate while maintaining high vacuum and can suppress the temperature rise of member in the vacuum chamber with time.
To achieve the above object, the present invention provides a heating and cooling apparatus for heating and cooling a substrate in a vacuum, comprising: a vacuum chamber; a radiation energy source positioned at the vacuum chamber on an atmosphere side configured so as to emit a heating light; an incidence part configured so as to cause the heating light from the radiation energy source to enter the vacuum chamber; a substrate-holding member configured so as to hold the substrate; and a transfer mechanism configured so as to transfer, in a heating state, the substrate held by the substrate-holding member to a heating position proximal to the radiation energy source, and to transfer, in a non-heating state, the substrate and the substrate-holding member to a non-heating position distant from the radiation energy source, wherein the substrate-holding member has a plate-like shape for placing the substrate thereon and has an outer shape larger than that of the incidence part for causing the heating light to enter the vacuum chamber.
The present invention suppresses the temperature rise of the members in the vacuum chamber with time, thus allowing stable heating and cooling the substrates with good reproducibility therebetween even when successive heating and cooling treatments are given.
The embodiments of the present invention will be described below in detail referring to the drawings. In the drawings given below, the parts having the same function are represented by the same reference numeral, and repeated description thereof is not given. Other than
In
The vacuum chamber 1 below the halogen lamp 2 contains a substrate-holding member 9 having a size larger than that of the incidence part to prevent incidence of heating light into the vacuum chamber. The material of the substrate-holding member 9 is preferably the one easy to absorb infrared light and easy to release heat; although silicon carbide is used in the first embodiment, aluminum nitride can be used. Other than those materials, the substrate-holding member 9 can be formed by: an integrally molded component made mainly of at least one element selected from the group consisting of silicon, carbon, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, and titanium carbide, or a compound thereof; an assembly of a laminated metal substrate with a plate made mainly of above element or compound thereof; or a substrate-holding member made of above integrally molded component coated with a metal film on one surface thereof. The material of above metal substrate and above metal film can be at least one metal selected from the group consisting of gold, silver, copper, aluminum, titanium, vanadium, chromium, iron, cobalt, nickel, zinc, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, tin, hafnium, tantalum, tungsten, iridium, and platinum, an alloy made mainly thereof, or a compound made mainly thereof.
The substrate-holding member 9 is supported by at least one supporting rod 16, and the supporting rod 16 is connected with a vertical-drive mechanism 15 positioned at atmosphere side via a bellows 11, thus the vertical-drive mechanism 15 drives the supporting rod 16 in the vertical direction. The vertical-drive mechanism 15 may be a motor-drive type or an air-cylinder drive type using compressed air. The vertical-drive mechanism 15 is connected with a control part (not shown in
A gate valve 14 for transferring the substrate is positioned on a side surface of the vacuum chamber 1 to allow carrying-in and carrying-out of the substrate 5 to and from adjacent vacuum chamber while maintaining the vacuum. At opposite side of the gate valve 14 for transferring the substrate in the vacuum chamber 1, an evacuation opening 41 is located to conduct evacuation of the vacuum chamber 1, and a vacuum pump for evacuation (not shown) can be installed thereat via a gate valve for vacuum sealing (not shown).
The vacuum chamber 1 is fabricated by aluminum or stainless steel having low gas-release rate, and the chamber at atmosphere side is wound with a sheath-heater for baking (not shown) and a cooling water pipe for cooling (not shown) therearound. When the vacuum chamber 1 is evacuated from the atmospheric pressure, electric power is applied to the sheath-heater to heat the vacuum chamber 1 to 150° C. or higher temperature to conduct baking for at least 2 hours, thus enhancing the gas-release from inside wall of the chamber. After completing the chamber baking, water is introduced to the cooling water pipe to cool the chamber to room temperature. When the vacuum in the vacuum chamber 1 reaches a saturation level, the preparation completes. However, the cooling water is continued to flow in order to prevent warming of the vacuum chamber 1 during the heating step. A gas inlet 19 is opened at least one position of the vacuum chamber 1.
Next is the description about the operation from the heating to cooling (natural cooling) of the substrate to the carrying-out of the substrate from the vacuum chamber in the first embodiment referring to the drawings.
As illustrated in
In not-heating state, the substrate-holding member 9 is descended to bring the substrate 5 apart from the halogen lamp. At this moment, by positioning the push-up pin 17 at the bottom surface of the vacuum chamber 1 (shown in
The sputtering apparatus illustrated in
According to the first embodiment, the sputter deposition chamber 24 has targets of Ta, Ru, IrMn, CoFe, and CoFeB mounted therein, and the sputter deposition chamber 25 has at least MgO target mounted therein, and the sputter deposition chamber 26 has at least CoFeB target and Ta target mounted therein. Using the vacuum-transfer mechanism 21, the Si substrate is transferred from the load-lock chamber 28 into vacuum. First in the etching chamber 27, impurities adhering onto the Si substrate are removed. After that, the vacuum-transfer mechanism 21 transfers the Si substrate to the sputter deposition chamber 24 to form a film of laminate of Ta (5 nm)/Ru (2 nm)/IrMn (6 nm)/CoFe (2.5 nm)/Ru (0.85 nm)/CoFeB (3 nm) on the Si substrate. Then, the vacuum-transfer mechanism 21 transfers the Si substrate from the sputter deposition chamber 24 to the sputter deposition chamber 25, which forms a film of MgO with about 1 nm of thickness on the laminate, thus forming the structure of Si substrate/Ta (5 nm)/Ru (2 nm)/IrMn (6 nm)/CoFe (2.5 nm)/Ru (0.85 nm)/CoFeB (3 nm)/MgO (1 nm). Next, the vacuum-transfer mechanism 21 transfers the Si substrate from the sputter deposition chamber 25 to the vacuum heating and cooling apparatus 29, which applies heating and cooling treatment to the transferred Si substrate (substrate 5) while transferring it. Finally, the vacuum-transfer mechanism 21 transfers the Si substrate from the vacuum heating and cooling apparatus 29 to the sputter deposition chamber 26, which laminates CoFeB (3 nm)/Ta (5 nm) on the laminate formed on the transferred Si substrate, thus completing the manufacture of the tunnel magnetoresistance element.
Next is the detail description about the treatments conducted in the vacuum heating and cooling apparatus 29 illustrated in
On receiving an instruction of heating and cooling treatment, a control part 1000 conducts control of opening the gate valve 14 for transferring the substrate. At this moment, the substrate 5 on which up to the MgO film was formed in the sputter deposition chamber 25 is transferred by the substrate-transfer mechanism 21 of the vacuum-transfer chamber 22 onto the push-up pin 17 which is waited at the transferring position in the vacuum heating and cooling apparatus 29. After that, the gate valve 14 is closed by the control of the control part 1000. At this moment, the control part 1000 controls the vertical-drive mechanism 15 to transfer the substrate 5 held by the push-up pin to the substrate-holding member 9, and to ascend the substrate-holding member 9 so that the substrate 5 is positioned at the heating position. In this action, the heating position is preferably set so that the distance between the halogen lamp 2 and the substrate 5 is 100 mm or less. In this state, according to an instruction of the control part 1000, electric power is applied to the halogen lamp 2 to irradiate the substrate 5 with the heating light from the atmosphere side through the quartz window 3. By setting the diameter of the substrate-holding member 9 to be slightly larger than that of the incidence part, the substrate-holding member 9 can block the heating light. As a result, there can be suppressed the effect of temperature increase with time by the heating light at the members below the substrate-holding member 9 inside the chamber and at the chamber itself. According to the first embodiment, the heating light shielding effect is attained by setting the diameter of the substrate-holding member 9 to 360 mm with respect to the diameter of 340 mm of the incidence part. When the temperature of the substrate 5 reaches a desired level, the control part 1000 decreases the electric power supplied to the halogen lamp 2 to perform the control so that the substrate keeps a certain temperature. The heat treatment of the substrate is thus conducted.
After a desired time has passed, the control part 1000 performs the control to stop electric power supply to the halogen lamp 2. Then, the control part 1000 controls the vertical-drive mechanism 15 to descend the substrate-holding member 9 which supports the substrate 5 subjected to the heat treatment, and transfers the substrate 5 onto the push-up pin 17. That is, the substrate 5 moves to the transferring position and preparation for transfer is conducted. Then, the control part 1000 opens the gate valve 14 to let the substrate-transfer hand of the substrate-transfer mechanism 21 carry-out the substrate 5 on the push-up pin 17.
In this procedure, in the heat treatment, the control part 1000 controls the drive of the substrate-holding member 9 so that the substrate 5 is positioned at the heating position, stops the substrate 5 at the heating position, and conducts the heat treatment. Then, on carrying-out the substrate, the control part 1000 controls the drive of the substrate-holding member 9 so that the substrate 5 is positioned at the transferring position, stops the substrate 5 at the transferring position, and prepares for the substrate transfer.
As described above, in the first embodiment, the substrate-holding member 9 can block the heating light by designing the diameter of the substrate-holding member 9 to be slightly larger than that of the incidence part. As a result, in a vacuum heating and cooling apparatus which can conduct rapid heating and rapid cooling of the substrate after deposition treatment while maintaining high vacuum condition, the temperature rise of the members in the chamber with time can be suppressed, and the temperature variation between substrates can be decreased.
According to the first embodiment, the temperature of substrate 5 and substrate-holding member 9 after the heat treatment decreases naturally with time. However, a long time may be required to reach the room temperature level. Regarding the substrate, it can be carried-out at a high temperature. For the substrate-holding member 9, however, when a next substrate is carried-in while the temperature of the substrate-holding member 9 is not sufficiently decreased, the thermal conduction from the substrate-holding member 9 may vary the initial temperature of the substrate before the irradiation with the heating light. For the case of successive heat treatment of substrate, the effect of accumulation of heat with time in the substrate-holding member 9 induces temperature variation among substrates, which may result in poor production yield. To prevent or decrease the accumulation of heat with time in the substrate-holding member 9, in the second embodiment, a cooling member 10 is positioned at lower part in the vacuum chamber 1, as illustrated in
The cooling member 10 is preferably made of a material with low gas-release rate and high thermal conductivity; the second embodiment uses aluminum.
Next is the description about the procedure of carrying-in, heating, cooling, and carrying-out the substrate according to the second embodiment referring to the drawings.
Then, the vacuum-transfer robot transfers the substrate from adjacent vacuum-transfer chamber into the vacuum heating and cooling apparatus.
Next is the description about the operation until reaching the heating position. First, the substrate-holding member ascends to above the front end of the push-up pin 17′, receives the substrate on the push-up pin 17′, and then further ascends and stops at a position within 100 mm from the halogen lamp 2. This position is the heating position. After that, the push-up pin 17′ descends, and stops when the front end of the push-up pin 17′ becomes at or below the level of the surface of the cooling member 10, thus completing the preparation for heating.
After completing the heating step, the substrate-holding member 9 descends down until contacting the cooling member 10 while having the substrate 5 placed thereon. The position of the substrate at this moment is a special position of cooling position in the non-heating positions (
With the procedure, the substrate-holding member 9 can maintain the cooling state in contact with the cooling member 10 until next substrate arrives, and thus the effect of accumulation of heat of the substrate-holding member 9 on the next substrate can be suppressed, which can decrease the variation of temperature between substrates. The structure may be the one to cool only the substrate-holding member 9.
During cooling step of the second embodiment, the substrate 5 is indirectly cooled by the cooling member 10 via the substrate-holding member 9. According to the third embodiment, for further increasing the cooling speed of the substrate, the substrate 5 is contacted with and placed directly on the cooling member 10 in the cooling step. Hence, the cooling speed can be increased. As illustrated in
In the third embodiment, the cooling member 10 is formed to a convex shape, the diameter at the upper stage part thereof is designed to be smaller than the inner diameter of the ring-shaped substrate-holding member 9, and the diameter at the lower stage part thereof is designed to be larger than the inner diameter of the ring-shaped substrate-holding member 9. The structure allows the substrate-holding member 9 to pass through the upper stage part of the cooling member 10 during cooling step and further allows the substrate-holding member 9 to be contacted with and directly placed on the convex stage surface of the lower stage part. As a result, the substrate-holding member 9 itself can also be cooled efficiently. To further efficiently cool the substrate-holding member 9, the diameter of the lower stage part of the convex cooling member 10 may be designed to be larger than the diameter of the substrate-holding member 9. Specifically, the diameter of the lower stage part of the convex cooling member 10 is set to 400 mm with respect to the diameter of 360 mm of the substrate-holding member. The convex cooling member 10 is not necessarily the integrally molded component, and may have a structure illustrated in
In the fourth embodiment, at least three rod-shaped substrate-supporting parts 92 are erected at edge part of the inner periphery of the ring-shaped substrate-holding member 9 to support the substrate (
Next is the description about the procedure of carrying-in, heating, cooling, and carrying-out the substrate according to the fifth embodiment referring to the drawings.
Further the substrate-transfer hand 12a shrinks to return into the vacuum-transfer chamber, the gate valve 14 is closed, and the substrate carrying-in operation is completed (
When the heating temperature of the substrate is high or depending on the kind of the substrate 5, on initiating the rapid cooling under the contact with the cooling member 10a, the thermal shock may generate crack on the substrate. To prevent the crack of the substrate, in the fifth embodiment, the substrate-holding member 9 does not descend without stopping, after completing the heating step, down to the cooling position contacting the cooling member 10b, but the vertical movement of the substrate-holding member 9 is controlled so that the substrate once stops at an interim position between the transferring position and the cooling position. That specific interim position to enhance the natural cooling is preferably more close to the cooling member 10a, and further preferably within 20 mm above the cooling member 10a. After allowing the substrate 5 to stand at the cooling position until the temperature decreases to a desired level or below, the substrate-holding member 9 is ascended to move the substrate 5 to the transferring position, thus completing the preparation for transfer (
With the procedure, rapid cooling of the heated substrate can be performed and the cooling state can be maintained, in which the substrate-holding member 9 contacts the cooling member 10b, until next substrate arrives, and thus the effect of accumulation of heat of the substrate-holding member 9 on the next substrate can be suppressed, thereby enabling decrease in the variation of temperature between substrates. Furthermore, elimination of the push-up pin, the vertical-drive mechanism and the bellows thereof can decrease the gas-release sources, and can maintain the high vacuum. In addition, the time of push-up pin action can be shortened in the substrate-transfer time, which improves the throughput. The cooling member may not be used, and the cooling member may cool only one of the substrate and the substrate-holding member.
In the fifth embodiment, it is necessary that the inner diameter of the ring-shaped substrate-holding member 9 is designed to be larger than the diameter of the substrate, while bringing the pitch circle diameter of each of the three substrate-supporting parts to be smaller than the diameter of the substrate in order to support the substrate. Thus, the substrate-supporting part may have a shape in which projection 93 is formed toward the inner periphery of the substrate-holding member 9 as illustrated in
With the structure, the contact area between the substrate and the cooling member 10a can be increased, thus increasing the cooling speed. Alternatively, the substrate 5 may be directly supported by the projections 93, not forming the substrate-supporting part 92 on the projection 93. In that case, there is needed a push-up pin. Since, however, the contact between the substrate-holding member 9 and the substrate 5 can be decreased, the thermal conduction between members during heating and cooling can be prevented or decreased, and thus the contact area with the cooling member can be increased.
First to sixth embodiments use a substrate-holding member having larger diameter than that of the incidence part to block the heating light, thus suppressing the temperature rise in the members and the wall surface at lower part of the vacuum chamber and decreasing the variation of temperature between substrates caused by accumulated heat with time. When, however, the substrate-holding member is directly exposed to the heating light, the substrate-holding member itself increases the temperature, which may induce the temperature rise in the members and the wall surface at lower part of the vacuum chamber by the heat radiation of the substrate-holding member. To this point, a structural design can eliminate the anxiety, and can further decrease the temperature rise with time in the members in the vacuum chamber. To eliminate the effect of radiation, in the seventh embodiment, the surface not subjected to irradiation of the heating light on the substrate-holding member, or the surface facing downward in the vacuum chamber, is coated with a metal film having low radiation factor, which suppresses the effect. The seventh embodiment uses gold considering the four conditions, low radiation factor, high melting point, high thermal conductivity, and high chemical stability.
In the fifth embodiment, a substrate-supporting part 92′ mounted on the substrate-holding member 9 is not necessarily a rod-shaped substrate-supporting part, and may be formed into an open-end ring shape in which the substrate-supporting part 92′ has a shape of elongated flat-plate and the flat plate is bent in a long axis direction thereof along the inner periphery end part of the ring-shaped substrate-holding member 9, as illustrated in
The term “heating position” referred to herein signifies the position at which the substrate should be positioned on heating the substrate, and the heating position is set to a position closer to the radiation energy source than to the non-heating position which is defined below, and specifically within 100 mm of distance between the substrate and the radiation energy source (halogen lamp in the eighth embodiment).
The term “non-heating position” referred to herein signifies the position at which the substrate should be positioned when not heating the substrate, and any position can be selected if only the substrate is distant from the radiation energy source more than from the heating position, specifically at any distance if only the substrate is distant from the radiation energy source by more than 100 mm. Therefore, the transferring position and the cooling position are the non-heating positions, both of which mean special positions of the non-heating position. According to the embodiments, the position to which the substrate 5 is placed on the cooling member 10 is the cooling position.
The term “transferring position” referred to herein signifies the position at which the substrate transferred from outside is firstly held, and which is positioned within the range of the non-heating position. According to the embodiments, the transferring position is set in a space facing the opening of the gate valve 14 for substrate transferring and in a space within a range of the width of the opening of the gate valve 14. In the embodiments 1 to 4, the substrate is held on the front end of the push-up pin, and in the embodiments 5 and 7, the substrate is held on the front end of the substrate-supporting part of the substrate-holding member 9.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-234927 | Oct 2009 | JP | national |
This application is a continuation application of International Application No. PCT/JP2010/067873, filed Oct. 12, 2010, which claims the benefit of Japanese Patent Application No. 2009-234927, filed Oct. 9, 2009. The contents of the aforementioned applications are incorporated herein by reference in their entities.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2010/067873 | Oct 2010 | US |
| Child | 13093906 | US |
