JP2005226109A - Cooling plate for sputtering apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling plate for a sputtering apparatus, which inhibits peripheral portions of a supply port and an exhaust port for a cooling medium from deforming and degrading due to heat, and consequently can be used for a longer period than ever. <P>SOLUTION: The cooling plate 10 for the sputtering apparatus has a target T connected to the surface 10a, a channel 12 for the cooling medium formed inside and the supply port 14 and the exhaust port 15 communicating with the channel 12 formed on a rear face 10b. In the cooling plate 10, the peripheral portions 16 and 17 of the supply port 14 and the exhaust port 15 are formed of a material having smaller thermal strain and higher mechanical strength against thermal fatigue than that in the other part 11. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cooling plate to which a sputtering target is fixed in a sputtering apparatus.

  In general, in a manufacturing process of a semiconductor or the like, a sputtering method is widely adopted as a method of forming a desired metal thin film on the surface of a substrate or the like. This sputtering method is a kind of vacuum film-forming method. A sputtering target (hereinafter abbreviated as a target) and a member on which a thin film such as a substrate is to be formed are placed in a container of a sputtering apparatus held in a low-pressure atmosphere. This is a method in which charged particles are made to collide with the target by applying a negative potential to the target by being opposed to each other, and sputtered particles scattered in the gas from the target by this impact are deposited on the surface of the member. .

  By the way, since a large amount of charged particles collide with the target during sputtering, the temperature rises with time. Therefore, a cooling plate made of a metal having excellent electrical conductivity and thermal conductivity is integrally fixed to the back side of the target in order to apply a negative potential to the target and suppress the heat generation. .

  3 and 4 show a conventional cooling plate of this type. The cooling plate 1 is a flat plate member made of a metal such as copper, and the target T is integrally fixed to the surface 1a by brazing. Has been. In the cooling plate 1, a flow path (U-shape in the figure) 2 for a cooling medium such as water is formed, and a cooling medium supply port 3 and a discharge port 4 are provided at both ends of the flow path 2, respectively. Is drilled.

  Here, the supply port 3 and the discharge port 4 are formed so as to open on the back surface 1b of the cooling plate 1, and a cooling medium (not shown) is respectively connected to the supply port 3 and the discharge port 4 via an O-ring. The supply pipe and the discharge pipe are connected.

  In the cooling plate 1 having the above configuration, the target T is usually brazed to the surface 1a using a brazing material having a melting point of about 150 ° C. containing indium (In) as a component. For this reason, at the time of joining of the target T, the cooling plate 1 is heated to the melting point or more of the brazing material and cooled after brazing. And the cooling plate 1 and the target T had a problem that since the thermal expansion coefficient is greatly different, the cooling plate 1 is warped or deformed due to the difference.

  In addition, since the target T is a consumable item, the heating and cooling described above are repeated in order to remove the target T that has become unusable and to join a new one. As the warpage and deformation progress, it becomes difficult to attach to the sputtering apparatus, or the target T is broken during sputtering.

  In particular, the peripheral portions of the supply port 3 and the discharge port 4 in the cooling plate 1 have a reduced thickness due to the formation of the flow path 2 for the cooling medium, and generally metals such as copper are mechanically strong. In addition to the disadvantage of becoming brittle early due to thermal fatigue caused by multiple use.

  For this reason, when the thermal strain is applied, or when the supply pipe or the discharge pipe is attached or detached in the replacement of the target T, a twist or bending moment acts on the peripheral portion, or a tensile stress acts on the peripheral portion. There is also a problem that the cooling plate 1 in such a state is no longer able to be repaired due to the progress of deformation and wear and leakage in the seal portion.

  As a conventional technique for suppressing the occurrence of warpage in the cooling plate 1 with respect to these problems, as shown in, for example, Patent Document 1 below, a soft material such as Sn is used between the target and the cooling plate. It is known that a buffer layer having a high ductility and a relatively high melting point is provided to reduce thermal strain on the target, thereby avoiding deformation and cracking of the target and the cooling plate.

As another prior art, in the following Patent Document 2, after joining a target to a cooling plate, this is placed on a surface plate provided with a vacuum suction hole, and vacuum suction is performed in the joining step. A method for correcting distortion such as warping has been proposed.
JP-A-61-250167 JP 2001-131738 A

  However, in these conventional techniques, although the warpage of the cooling plate and the target can be suppressed, thermal fatigue, thermal distortion or mechanical stress acting at the time of pipe attachment / detachment at the peripheral portion of the supply port and the discharge port, etc. It is impossible to prevent the occurrence of leakage in the resulting seal portion, and thus has the disadvantage that the service life of the cooling plate cannot be extended.

  The present invention has been made in view of such circumstances, and can suppress deformation and deterioration of the peripheral portion of the supply port and the discharge port of the cooling medium due to heat. It is an object of the present invention to provide a cooling plate for a sputtering apparatus that can be used.

  In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that a target is bonded to the front surface, a cooling medium flow path is formed therein, and a cooling medium supply port communicates with the flow path on the back surface. In the cooling plate for a sputtering apparatus in which the discharge port is formed, the peripheral portion of the supply port and the discharge port is made of a material having a smaller thermal strain than the other parts and a high mechanical strength due to thermal fatigue. It is characterized by this.

  The invention according to claim 2 is characterized in that the other part according to claim 1 is made of copper, a copper alloy, aluminum or an aluminum alloy, and the peripheral part is made of stainless steel. Is.

  According to the first or second aspect of the invention, the peripheral portions of the supply port and the discharge port in the cooling plate are formed of a material that has a smaller thermal strain than other portions and a high mechanical strength due to thermal fatigue. Therefore, the thermal distortion of the peripheral portion can also be reduced by heating and cooling during target bonding.

  In addition, the peripheral portion has increased mechanical strength due to thermal fatigue. As a result, thermal fatigue caused by repeated use due to heating and target replacement and mechanical stress acting during pipe replacement Since the softening and embrittlement are reduced, deformation and wear can be greatly suppressed. For this reason, even if it is used for a long period of time, the seal portion with the refrigerant pipe does not leak, and the service life can be extended.

1 and 2 show an embodiment of a cooling plate for a sputtering apparatus according to the present invention, and reference numeral 10 in the drawing denotes a cooling plate in which a target T is joined to a surface 10a.
The cooling plate 10 is a flat plate having a body portion 11 made of copper, copper alloy, aluminum, or aluminum alloy, and a U-shaped cooling medium flow path 12 is formed inside the cooling plate 10. Has been.

As shown in FIG. 2, the flow path 12 has a groove portion processed from the back surface 10 b side of the cooling plate 10, and the step 12 a formed on both sides of the groove portion is the same as the cooling plate 10. The sealing plate 13 made of metal is closed by being joined by welding or the like.
In addition, a supply port 14 and a discharge port 15 for the cooling medium are formed in the sealing plate 13 at both ends of the flow path 12.

  Here, the supply port 14 and the discharge port 15 have large-diameter holes 14a and 15a formed in the sealing plate 13, respectively, and ring-shaped connection portions (periphery portions) in the holes 14a and 15a. ) 16 and 17 are joined together.

These connection portions 16 and 17 are made of stainless steel, and are fitted and integrated into the holes 14a and 15a by electron beam welding.
A cooling medium supply pipe is connected to one connecting portion 16 via an O-ring, and the cooling medium discharge pipe is similarly connected to the other connecting portion 17 via an O-ring. It has become so.

An example of the cooling plate having the above configuration is as follows.
As a main body portion of the cooling plate 10, a plate material made of oxygen-free copper (JIS C1020) having a length of 300 mm, a width of 150 mm, and a thickness of 11 mm is used. And the U-shaped groove part of width 50mm and depth 5mm is formed in the back surface side of this cooling plate 10 by machining.

  Next, a sealing material 13 made of oxygen-free copper (JIS C1020) having the same shape and a thickness of 4 mm that fits into the step portion 12a of the groove portion is prepared. Then, long holes having a size of 34 × 19 are formed in both ends of the sealing plate 13 by machining.

  Next, stainless steel (JIS SUS304) connection parts 16 and 17 having a supply port 14 or a discharge port 15 drilled are fitted into the long hole while being processed into the same outer dimensions as the long hole. Then, they are joined by electron beam welding. And the sealing board 13 with which these connection parts 16 and 17 were integrated is inserted in the step part 12a of the said groove part, and it joins by electron beam welding. Thereby, the flow path 12 having the connection portions 16 and 17 is formed.

  As described above, according to the cooling plate 10 having the above-described configuration, the connection portions 16 and 17 of the supply port 14 and the discharge port 15 are smaller in thermal distortion than the main body portion (other portions) 11 and are thermally fatigued. Therefore, the thermal distortion of the connecting portions 16 and 17 can be reduced by heating and cooling when the target T is joined.

  In addition, since the mechanical strength due to thermal fatigue is higher than that of the main body portion 11, the connection portions 16 and 17 have thermal fatigue caused by repeated use by heating or target replacement, and the supply port 14 Further, the softening of the mechanical stress acting when the supply pipe or the discharge pipe is attached to or detached from the discharge port 15 is reduced. For this reason, the deformation and wear in the connecting portions 16 and 17 can be significantly suppressed, and therefore, even when used for a long period of time, there is no leakage in the seal portion between the cooling medium supply pipe and the discharge pipe. The service life can be extended.

In the above embodiment, only the case where the U-shaped cooling medium flow path 12 is formed on the cooling plate 10 has been described. However, the present invention is not limited to this, and the I-shaped, W-shaped, meander-shaped or Various shapes such as a combination of these can also be applied. Further, the number of the flow paths 12 is not limited to one.
Further, the material of the main body portion 11 and the connection portions 16 and 17 are not limited to those described above.

It is a top view which shows one Embodiment of this invention. It is the II-II sectional view taken on the line of FIG. It is a top view which shows the conventional cooling plate. It is the IV-IV sectional view taken on the line of FIG.

Explanation of symbols

10 Cooling plate 10a Front surface 10b Back surface 11 Body part (other part)
12 Flow path of cooling medium 14 Supply port 15 Discharge port 16, 17 Connection part (peripheral part)
T target

Claims (2)

In the cooling plate for a sputtering apparatus in which the target is bonded to the front surface, the flow path of the cooling medium is formed inside, and the supply port and the discharge port of the cooling medium communicating with the flow path are formed on the back surface.
A cooling plate for a sputtering apparatus, wherein the peripheral portions of the supply port and the discharge port are formed of a material having a smaller thermal strain than other portions and a high mechanical strength due to thermal fatigue.   2. The cooling plate for sputtering according to claim 1, wherein the main body portion is made of copper or a copper alloy, aluminum or an aluminum alloy, and the peripheral portion is made of stainless steel.

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