JP2008095204A - Thermally conductive metal sheet - Google Patents

Abstract

A heat conductive metal sheet 20 interposed between a target material and a back plate of a sputtering apparatus has good heat conductivity and the target material is heated to melt 27 metal layers of the heat conductive metal sheet 20. Even so, the outflow of the metal layer 27 can be prevented.
A metal layer 27 is made of a low melting point metal material, and the metal layer 27 is made of a material having a melting point higher than that of the low melting point metal material constituting the metal layer 27 and has a hole 30a. The foil 30 is a thermally conductive metal sheet 20 embedded in parallel to the surface of the metal layer 27.
[Selection] Figure 2

Description

The present invention relates to a thermally conductive metal sheet interposed between a target material and a back plate of a sputtering apparatus.

In the structure of the cathode portion of the conventional sputtering apparatus, the target material is subjected to ion bombardment during sputtering and becomes high temperature, and therefore the target material is melted. In order to avoid such melting of the target material, it has been necessary to cool the target material by providing a cooling circulation channel pipe or the like on the back plate holding the target material. Therefore, a cooling method or a structure for cooling the target material as efficiently as possible has been studied. As an example of a cathode portion of a conventional sputtering apparatus, there is a structure disclosed in Patent Document 1 .

In the cathode portion disclosed in Patent Document 1 , the target material and the back plate are brazed (or soldered) using a low melting point metal in order to efficiently perform the cooling effect of the target material. Thus, since the heat exchange between the back plate and the target material is improved by directly joining the target material and the back plate, this brazing method is widely used.

However, according to the structure of the cathode portion of Patent Document 1 , it is necessary to remove the back plate at the same time when replacing the target material. In addition, since the back plate is provided with a cooling circulation channel pipe, each time the target material is changed, the channel tube must be removed from the back plate every time. As an improvement, there is a structure disclosed in Patent Document 2 .

In the structure of Patent Document 2 , a heat conductive metal sheet (flexible heat transfer sheet) is interposed between the target material and the back plate. With this structure, the thermal conductivity between the target material and the back plate is ensured, and when replacing the target material, it is only necessary to replace the thermally conductive metal sheet and the target material. Maintenance management becomes easier.

U. S. P4,414,086 Japanese Patent Laid-Open No. 5-59540

However, the cathode part of the sputtering apparatus of Patent Document 2 described above has the following problems.

  In the conventional cathode part, after providing a heat conductive metal sheet between the target material and the back plate, a press plate (in order to improve the thermal contact between the target material and the metal sheet and between the back plate and the metal sheet, A presser ring is used to press-contact the target material to ensure surface contact with the back plate. However, since the contact area between the metal sheet and the back plate and the target material is large, if a uniform contact surface is to be secured with respect to the contact surface of the metal sheet, the target material strongly strengthens the heat conductive metal sheet. It is necessary to press contact. When the metal sheet is pressed with a strong force, the metal sheet is made of a low melting point metal (In, Pb, etc.) material, and the mechanical strength is weak, so the metal sheet itself is deformed. There is. For this reason, the thermal conductivity of the metal sheet deteriorates and cannot be put to practical use.

  In addition, when high power is applied to the cathode electrode of the sputtering apparatus, the metal sheet is melted by the temperature of the target material and flows out from between the back plate and the target material, and as a result, between the target material and the back plate. Thermal conductivity deteriorates. Due to such melting of the metal sheet, the cathode electrode and the ground are short-circuited, causing a short circuit or contamination of the target material.

Therefore, even when pressed between the backing plate and the target material comprises a deformation is small metal sheets, also even if a high power is applied to the target material side, the appearance of the metal sheet which molten metal sheet does not flow out Was desired.

Therefore, the present invention provides a metal layer composed of a low-melting-point metal material made of a material having a melting point higher than that of the low-melting-point metal material constituting the metal layer and having a hole, It is intended to provide a thermally conductive metal sheet characterized by being embedded in parallel to the above.

In this invention, in the metal layer of the heat conductive metal sheet, high power is applied to the target material side, or the target material is not closely attached to the back plate via the heat conductive metal sheet. In this case, a metal foil having holes is embedded in parallel to the surface as a non-melting metal base material at the elevated temperature of the target material. For this reason, when the adhesion between the target material and the metal sheet is good and low power is applied to the target material side and the metal layer is not melted, the direction parallel (horizontal) to the metal sheet surface compared to the case of the metal layer alone Increases the mechanical strength. Therefore, even when the back plate and the target material are pressed against each other with a strong force, the deformation in the thickness direction of the metal sheet itself inserted between the two is less than in the past, so the back plate is more than conventional. And the thermal conductivity between the target material is improved.

In addition, when the target material is not closely attached to the back plate via the heat conductive metal sheet, or even if the target material is closely attached, the high power is applied to the target material side and the metal layer Even when is melted, the base material (metal foil having holes) is embedded in the metal sheet, so that the molten metal layer stays in the holes of the base material. For this reason, the molten metal layer due to the temperature rise of the target material does not flow out between the back plate and the target material.

  In the present invention, it is preferable that the material of the metal layer be one kind of material selected from materials of indium, lead, and In—Pb alloy.

  Since these materials are low melting point metal materials and rich in flexibility, sufficient adhesion with the target material or the back plate can be ensured. Further, since this material has good thermal conductivity, the cooling temperature from the back plate can be efficiently transmitted to the target material.

  In the present invention, the base material is preferably one material selected from copper, aluminum, Cu—Al alloy and carbon.

  Since such a material has a higher mechanical strength than the material of the metal layer, even if a pressure stress is applied to the metal sheet, the deformation of the metal sheet can be reduced as compared with the conventional metal layer alone. .

As a reference example of the present invention , it is preferable that the substrate has a mesh shape (mesh shape). High power even when the target material is not closely attached to the back plate via the heat conductive metal sheet, or even if the target material is closely attached, by making the shape of the base material a mesh. Even when the metal layer is melted at the temperature of the target material when applied to the target material side, this metal layer stays in the voids of the mesh due to the surface tension between the base materials, thus preventing the metal layer from flowing out. Can do.

In the present invention, it is preferable to use a plurality of layers of metal foil having holes as the base material.

  In these cases as well, the molten metal layer stays between the substrates or in the holes of the metal foil for the same reason as described above, so that the metal layer can be prevented from flowing out.

According to the heat-conductive metal sheets of this invention, it is then arranged a substrate made of holed metal foil into the metal layer. For this reason, even if a metal sheet is inserted between the target material and the back plate and the target material is pressed against the back plate with a strong force, the mechanical strength of the base material is greater than the strength of the metal layer, The deformation of the metal sheet is reduced compared to For this reason, the cooling effect from the back plate side to the target material side is remarkably improved as compared with the conventional case. In addition, even if high power is applied to the target material side and the metal layer melts due to the temperature of the target material, the base material prevents a short circuit between the cathode electrode and the ground in order to prevent the metal layer from flowing out. It is possible to avoid the contamination of the target material.

Referring to FIG, used for mosquito cathode section, an embodiment of a thermally conductive metal sheet of the present invention. 1 to 5 only schematically show the shape, size, and arrangement relationship of each component to the extent that the present invention can be understood. Moreover, the diagonal line attached | subjected to the top view of FIGS. 1-3 is a line attached in order not to represent a cross section but to demonstrate a component clearly.

Referring to FIG 5, it will be described main structure of the cathode portion of the scan sputtering apparatus. FIG. 5 is a cross-sectional view showing the main configuration of the cathode portion of the sputtering apparatus.

  The cathode unit 10 includes a cathode electrode 12, a vacuum chamber wall 14, a cooling circulation channel pipe 16, a back plate 18, a heat conductive metal sheet (hereinafter also referred to as a metal sheet) 20, a target material 22, a holding plate 24, and a magnet ( Electromagnet) 26. In this embodiment, a back plate 18, a metal sheet 20 and a target material 22 are sequentially provided on the cathode electrode 12. In addition, a presser plate 24 is provided around the target material 22, and the presser plate 24 presses the target material 22, the metal sheet 20, and the back plate 18 to press the metal sheet 20, the back plate 18, and the metal sheet. 20 and the target material 22 are brought into close contact with each other.

  Further, a cooling circulation channel pipe 16 is provided on the bottom surface of the back plate 18, and the cooling water is circulated from the arrow A to the arrow B in FIG. 5. Further, a magnet (electromagnet) 26 is provided below the back plate 18, and magnetic lines of force are generated around the target material 22 by supplying electric power to the electromagnet 26. Further, a vacuum chamber wall 14 is provided on both sides of the cathode electrode 12 to hold the cathode portion 10 in a vacuum.

[ Reference example of thermally conductive metal sheet]
Next, referring to FIGS. 1A, 1B, and 1C, a reference example of the thermally conductive metal sheet used in the cathode portion of the present invention will be described. 1A is a plan view of a metal sheet, and FIGS. 1B and 1C are cross-sectional views taken along a line cut along line XX in FIG. Indicates.

In this reference example , the heat conductive metal sheet 20 is attached when the target material 22 is not closely attached to the back plate 18 via the heat conductive metal sheet 20, or the target material 22 is attached closely. However, when high power is applied to the target material 22 side, the metal layer 27 made of a heat conductive material that melts at the temperature of the target material 22, and the target material scattered and provided in the metal layer 27 At a temperature of 22, it is constituted with a non-melting substrate 28. Here, with reference to (A)-(C) of FIG. 4, it demonstrates per the state in which the target material is not closely_contact | adhered to the metal sheet, and the closely_contact | adhered state. 4A, 4 </ b> B, and 4 </ b> C each show a cut section at a position cut along a base material that extends with a metal sheet sandwiched between a back plate and a target material.

  That the target material 22 is not in close contact with the metal sheet 20 means a state in which a gap 36 is generated between them ((A) in FIG. 4). Further, although the metal sheet 20 is sandwiched between the back plate 18 and the target material 20, it is said that the metal sheet 20 is not in close contact even when the film thickness of the metal sheet 20 is not different from the film thickness before attachment (see FIG. 4 (B)).

  That is, for example, if the thickness t of the metal sheet 20 is 5 mm, the target material 22 is not in close contact with the metal sheet 20 when the thickness of the metal sheet 20 is not changed.

  On the other hand, the state in which the film thickness t of the metal sheet 20 is reduced to the film thickness Δt by press-contacting between the back plate 18 and the target material 22 is herein referred to as a close contact state (FIG. 4). (C)). That is, for example, a state in which the thickness t of the metal sheet 20 is about 5 mm is changed to a thickness of less than 5 mm is referred to as a close contact state. Moreover, high power means electric power of 2 kw or more.

  In addition, the base material 28 (28a and 28b) in the metal layer 27 is arranged in a mesh shape by superimposing the base material 28 vertically and horizontally in the metal layer 27 using a substantially straight base material 28. ((A) in FIG. 1). 1 and 2, the base material in the horizontal direction is denoted by reference numeral 28 b and the base material in the vertical direction is denoted by reference numeral 28 a with respect to the surface of the metal sheet 20. The metal layer 27 is also embedded in the gap portion 29 surrounded by the base materials 28a and 28b.

  Further, as the material of the metal layer 27, it is preferable to select a material having good thermal conductivity and good surface contact between the back plate 18 and the target material 22. Here, a low melting point metal material such as indium (In) is used as the material of the metal layer 27. Instead of the In material, lead (Pb), indium-lead (In-Pb) alloy, or the like may be used.

  In addition, as the material of the base material 28, when the target material 22 is not closely attached to the back plate 18 via the metal sheet 20, or even when the target material 22 is closely attached, high power is applied to the target material 22 side. In this case, it is preferable to select a material that is not melted at the temperature of the target material 22 and does not form a solid solution with the metal layer 27 and has good wettability with the metal layer 27. Here, for example, copper (Cu) is used as such a material. Aluminum (Al), Cu—Al alloy, carbon (C), or the like may be used instead of the copper material.

  In order to form the metal sheet, first, a heat-resistant plate (for example, a quartz glass plate) (not shown) is prepared, and base materials 28a and 28b are arranged on the surface of the plate in a mesh shape. ((A) of FIG. 1).

  Thereafter, a molten low melting point metal (for example, indium) is filled on the plate so as to embed the mesh-like substrates 28a and 28b. By such a method, the metal sheet 20 which consists of the metal layer 27 and the base material 28 is formed ((B) of FIG. 1).

In the reference example described above, since the mesh-like base material 28 is scattered in the metal layer 27, only the mechanical strength in the parallel (horizontal) direction with respect to the surface of the metal sheet increases. Further, in order to increase the contact surface between the target material 22 and the metal sheet 20 or the contact area between the back plate and the metal sheet, even if the target material 22 is pressed against the back plate 18 with a stronger force than before, in the present invention, Since the base materials 28a and 28b are scattered in the metal layer 27, the mechanical strength of the metal sheet 20 increases accordingly. As a result, the deformation of the metal sheet 20 is reduced, and the thermal conductivity from the back plate 18 to the target material 22 is improved as compared with the conventional case.

Next, with reference to FIG. 1C, a reference example in which the base material in the metal sheet is formed in a wave shape will be described. (C) of FIG. 1 shows a cross section of the metal sheet portion when the base material is formed in a wavy mesh shape.

  In order to form the metal sheet having the corrugated base material 28, the corrugated base materials 28c and 28d knitted longitudinally and laterally on the quartz glass described above are disposed, and then the void surrounded by the base materials 28c and 28d. A metal layer 27 is embedded in a portion (not shown).

  Thus, by making the base materials 28c and 28d in the metal layer 27 into a wavy shape, the regions of the base materials 28c and 28d are widely distributed in the thickness direction of the metal sheet 20. The thermal conductivity of the metal sheet 20 is better than that obtained by forming the material 28 into a striped mesh shape ((B) in FIG. 1). Therefore, the cooling effect from the back plate 18 side to the target material 22 is further improved.

  1A and 1B show an example in which the base material 28 is formed in a mesh shape (mesh shape) or a grid shape. However, the shape is not limited to this, and the base material 28 is made of metal. The layers 27 may be randomly scattered in the layer 27 (not shown).

[ Thermal conductive metal sheet according to an example of the present invention ]
Next, with reference to FIG.2 and FIG.3, it demonstrates about the example of the metal sheet which provided the metal foil which has a hole in the metal layer. 2A shows a plan view of a thermally conductive metal sheet according to an example of the present invention , and FIG. 2B corresponds to a position cut along line YY in FIG. A cross section cut is shown.

In this example , a metal foil 30 having a square hole is used as the substrate 30. In the present invention, three metal foils 30 are embedded in the metal layer 27. Here, an example in which three layers of the metal foil 30 are embedded in the thickness direction of the metal sheet is shown, but the metal foil 30 may be one layer, two layers, or three or more layers. The metal layer 27 is also filled in the hole 30a of the metal foil.

  As described above, in this embodiment, since the metal foil 30 with three layers is disposed in the metal layer, the mechanical strength of the metal sheet is a metal in which the mesh-like base material described above is embedded. Compared with the sheet, there is an advantage of further increase.

  Next, referring to FIGS. 3A and 3B, the structure of the metal sheet when the base material in the metal layer is a metal foil having slit-like holes will be described. 3A shows a plan view of the metal sheet, and FIG. 3B shows a cross-sectional cut corresponding to the position cut along the line ZZ in FIG.

  In this embodiment, a metal foil 32 having slit-like holes 34 is used as the base material 32, and the metal foil 32 is embedded in the metal layer 27. For this reason, the hole 34 is also filled with the metal layer 27.

According to the example of the present invention described above, only the mechanical strength in the parallel (horizontal) direction with respect to the metal sheet surface is increased by dispersing the base material made of the metal foil 30 (32) with holes in the metal layer 27. To do. Further, in order to increase the contact surface between the target material 22 and the metal sheet 20 or the contact area between the back plate 18 and the metal sheet 20, even if the target material 22 is pressed against the back plate 18 with a stronger force than before, this In the present invention, since the base material 30 (32) is scattered and provided in the metal layer 27, the mechanical strength of the metal sheet 20 increases accordingly. As a result, even if the back plate 18 and the target material 22 are pressed against each other with a large force, the deformation of the metal sheet 20 is reduced as compared with the conventional case, and between the metal sheet and the back plate and between the metal sheet and the target material. Since the surface contact is also improved, the cooling effect from the back plate 18 to the target material 22 is remarkably improved as compared with the conventional case.

  In addition, even when high power is applied to the target material 22 side and the metal layer 27 is melted due to the temperature of the target material 22, in the present invention, a base material made of the metal foil 30 (32) with holes is provided in the metal layer 27. Since the metal layer 27 is provided, the metal layer 27 stays in the holes 30a and 34 of the base material, and the metal layer 27 can be prevented from flowing out.

Next, the results of experiments on the shape of the target material and the presence or absence of melting of the metal layer using the above-described reference example and the metal sheet of the present invention will be described below.

  In the case of a 6-inch (about 15.24 cm) target material 22, when the metal sheet 20 is mounted on the back plate 18 and pressed between the target material 22 and the back plate 18, the space between the target material 22 and the metal sheet 20 is reached. Will be in close contact. At this time, the metal layer 27 does not melt even when power of 1.5 to 2 kw is applied to the 6-inch target material, but the metal layer 27 melts when power of 2 kw or more is applied. However, no outflow of the metal layer 27 was observed.

  On the other hand, in the case of the 9-inch (about 22.86 cm) target material 22, when the metal sheet 20 is mounted on the back plate 18 and the target material 22 and the back plate 18 are pressed against each other, the target material 22 and the metal sheet 20 It will be in the state which does not adhere between. At this time, if electric power is applied to the target material 22 for 1 kw or more, the metal layer 27 is melted. Even in the case of 9 inches, no outflow of the metal layer 27 was observed.

Moreover, in the reference example and the example of the present invention described above, if the metal sheet 20 is not melted during sputtering, the metal sheet 20 can be reused when the target material 22 is replaced. The economic effect is also great.

  Further, since the metal sheet 20 is provided between the back plate 18 and the target material 22, there is an advantage that maintenance when the target material 22 is replaced becomes easy.

(A)-(C) are the top views and a cross section which are provided in order to demonstrate the structure of the heat conductive metal sheet which concerns on a reference example . (A)-(B) are the top views and sectional drawings provided in order to demonstrate the structure of the heat conductive metal sheet which concerns on an example of this invention. (A)-(B) are the top views and sectional drawings with which it uses for demonstrating the modification of the structure of the heat conductive metal sheet which concerns on an example of this invention. (A)-(C) are the figures for demonstrating the contact | adherence state of a target material and a metal sheet. It is sectional drawing with which it uses in order to demonstrate the cathode part of the sputtering device of this invention.

Explanation of symbols

10: Cathode part 12: Cathode electrode 14: Wall of vacuum chamber 16: Cooling circulation channel pipe 18: Back plate 20: Thermally conductive metal sheet 22: Target material 24: Holding plate 26: Magnet (electromagnet)
27: Metal layer 28: Substrate 28a: Substrate in a direction transverse to the metal sheet surface 28b: Substrate in a direction perpendicular to the metal sheet surface 30, 32: Metal foil with a hole

Claims (6)

A metal foil made of a material having a higher melting point than the low melting point metal material constituting the metal layer and having a hole is embedded in the metal layer made of the low melting point metal material in parallel to the surface of the metal layer. A thermally conductive metal sheet characterized by the above. The thermally conductive metal sheet according to claim 1, wherein the thermally conductive metal sheet is interposed between a target material and a back plate of a sputtering apparatus. The heat conductive metal sheet according to claim 1 or 2, wherein a plurality of metal foils are embedded in the thickness direction of the metal layer. Low melting point metal material constituting the metal layer is indium (In), lead (Pb) and claims 1 to any one of the 3, characterized in that a type class selected from among an In-Pb alloy The thermally conductive metal sheet according to item. The heat conductive metal sheet according to any one of claims 1 to 4, wherein the metal foil is made of a material that does not form a solid solution with the metal layer. The material of the metal foil, copper (Cu), aluminum (Al) as claimed in any one of claims 1 to 5, characterized in that a type class selected from among and Cu-Al alloy Thermally conductive metal sheet.

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