JP2017119898A - Sputtering target, and sputtering apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sputtering target and a sputtering apparatus capable of cooling the whole area of a target homogeneously.SOLUTION: A sputtering target 1 or a sputtering target 1 to be used for sputtering, comprises: the sputtering target 1 to be used in a sputtering and made of a material to be sputtered and having an inner circumference 1a formed of a material to be sputtered and having the shape of a portion of a conical surface; and a backing plate 2 formed of a cooling water passage 4, in which cooling water flows, for cooling the target 1 with a cooling water passage 4. In the target 1, the thickness corresponding to the distance between an inner circumference 1a or a target sputter face to be sputtered and a target cooling face 1b or the face on the side opposite to the inner circumference 1a and to be cooled by the cooling water passage 4 is homogeneous.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sputtering target and a sputtering apparatus used for sputtering.

  The sputtering apparatus evacuates the chamber, applies a voltage between the wafer substrate on which the film is applied and the sputtering target that is the raw material of the film, and moves ions such as argon at a high speed by the applied voltage to the sputtering target. Colliding and repelling the particles of the sputtering target, and attaching the repelled particles to the wafer substrate to form a film.

  An example of the sputtering target in this sputtering apparatus is shown in FIG. 5 (Patent Document 1). The sputtering target 41 has a material target portion 42 to be sputtered and a backing plate 43 having a function of cooling the material target portion 42. The entire surface of the bonding portion 44 of the backing plate 43 is bonded and bonded to the entire back surface of the material target portion 42. By cooling the backing plate 43, the material target portion 42 is cooled via the joint portion 44, and the heat generation of the sputtering target 41 is suppressed.

  In recent years, an electron cyclotron resonance sputtering apparatus (hereinafter referred to as an ECR sputtering apparatus) has been used. The ECR sputtering apparatus accelerates positive ions such as argon in plasma generated by utilizing an electron cyclotron resonance phenomenon by an electric field to collide with the sputtering target, repels particles of the sputtering target, and repels the repelled particles to the wafer substrate. Adhere to form a film.

  As a sputtering target used in an ECR sputtering apparatus, a plate type target or a cone type target has been used. Since the cone type target has a large sputter area, an improvement in the film formation rate can be expected. In addition, since the sputtered particles can be emitted from various directions with respect to the workpiece, it is possible to improve the film formation distribution.

  FIG. 6 shows a configuration diagram of a cone-type sputtering target. The cone-type sputtering target includes a target 51 having a cone-shaped inner peripheral surface (sputter surface) and a triangular cross-sectional shape, a backing plate 52 joined to the target 51 by a bonding material 53, an upper portion of the backing plate 52, and And a cooling block 54 in contact with the outer periphery of the target 51.

  A cooling water channel 55 is provided in the cooling block 54 made of a copper ring. The cooling water channel 55 is cooled by the cooling water flowing through the cooling water channel 55, and the target 51 can be cooled from the cooling block 54 via the backing plate 52.

JP 2000-345330 A

  However, in the cone type sputtering target shown in FIG. 6, the cooling efficiency is poor because only the cooling block and the target are brought into contact with each other, and cooling from the backing plate on the lower surface of the target cannot be performed. The target surface cannot be reliably and uniformly cooled.

  For this reason, there has been a problem that the bonding material 53 is melted due to heat generated on the bonding surface between the target 51 and the backing plate 52, particularly on the center side of a circle far from the cooling block. Further, there is a problem that the sputtering method becomes non-uniform in the thickness direction due to the temperature difference in the radial direction of the target surface (sputter surface).

  An object of the present invention is to provide a sputtering target and a sputtering apparatus that can reliably and uniformly cool the entire sputtering surface of the target.

  In order to solve the above problems, a sputtering target according to the present invention is a sputtering target used for sputtering, which is formed from a material to be sputtered, and an inner peripheral surface has a shape of a part of a conical surface, A cooling water channel through which cooling water flows is formed, and includes a backing plate that cools the target by the cooling water channel, and the target is opposite to the inner peripheral surface, which is a target sputtering surface to be sputtered. The thickness corresponding to the distance from the target cooling surface cooled by the cooling water channel is uniform.

  Further, a bonding material for bonding the target and the backing plate is further provided, and the bonding material is interposed between the target and the backing plate with a uniform thickness.

  Preferably, the cooling water channel is formed in an annular shape inside the backing plate so as to face the target cooling surface over the entire circumference of the target cooling surface.

  Preferably, the cooling water channel is formed so that one surface of the cooling water channel is parallel to the target cooling surface.

  According to the present invention, since the thicknesses of the target sputtering surface to be sputtered and the target cooling surface to be cooled by the cooling water channel are uniform, the entire area of the target sputtering surface can be cooled uniformly, and thereby the sputter target. Prevents melting of the bonding material interposed between the backing plate and the backing plate. Moreover, by performing uniform cooling of the target surface (sputtering surface), the sputtering rate can be made uniform over the entire sputtering surface.

It is a figure which shows the structure of the sputtering target which concerns on Example 1 of this invention. It is a figure which shows the structure of the sputtering device containing the sputtering target which concerns on Example 1 of this invention. It is a figure which shows the structure of the sputtering target which concerns on Example 2 of this invention. It is a figure which shows the structure of the sputtering target which concerns on Example 3 of this invention. It is a figure which shows an example of a structure of the conventional sputtering target. It is a figure which shows another example of a structure of the conventional sputtering target.

  Hereinafter, embodiments of a sputtering target and a sputtering apparatus of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view illustrating a configuration of a sputtering target according to Example 1 of the present invention. As shown in FIG. 1, this sputtering target has a target 1, a backing plate 2, and a bonding material 3, and these members are formed in an annular shape.

  The target 1 is formed of a material to be sputtered, for example, Si or NiZnFe, and has a shape in which the inner peripheral surface is a part of a conical surface (cone shape). The target 1 has a thickness corresponding to the distance between the target sputtering surface 1 a to be sputtered (that is, the inner peripheral surface on the target) and the target cooling surface 1 b that is the surface facing the inner peripheral surface and is cooled by the cooling water channel 4. Is uniform. Preferably, the distance between the target sputtering surface 1a and the target cooling surface 1b is uniform over the entire region, but the distance between the target sputtering surface 1a and the target cooling surface 1b is slightly different in a small region. It doesn't matter. In other words, the shape of the target 1 is formed by annularly forming a plate material having a substantially rectangular shape in cross-section, so that the shape of a part of the cone (that is, the shape in which the bottom surface of the cone and the surface near the vertex are removed from the cone) is there.

  The backing plate 2 is made of a material having a high thermal conductivity, such as copper, and has a triangular cross section and is formed in an annular shape. A cooling water channel 4 is formed in the inside of the backing plate 2 in an annular shape. The cooling water channel 4 has a circular cross section, and cooling water (not shown) flows through the cooling water channel 4. The cooling water channel 4 cools the target 1 through the bonding material 3.

  The bonding material 3 is made of a material having good thermal conductivity, such as indium, and joins the target 1 and the backing plate 2. The bonding material 3 is preferably formed to have a uniform thickness, whereby the distance from the backing plate 2 to the target cooling surface 1b can also be made uniform.

  According to the sputtering target of Example 1 configured as described above, the target 1 is formed in an annular shape having a substantially rectangular cross section, and thus the target to be cooled by the sputter target sputtering surface 1 a and the cooling water channel 4. The thickness corresponding to the distance from the cooling surface 1b is uniform over the entire target sputtering surface.

  Therefore, the entire area of the target sputtering surface 1a of the target 1 can be uniformly cooled by the cooling water flowing in the cooling water channel 4 via the bonding material 3, and the temperature can be lowered to a substantially uniform temperature. Therefore, melting of the bonding material 3 due to heat generation of the target 1 can be prevented. Moreover, by setting the target sputtering surface 1a to a uniform temperature, the sputtering rate is uniform over the entire surface, and the consumption efficiency of the target 1 can be improved.

  Furthermore, the target 1 shown in FIG. 6 has a triangular shape, but the target 1 shown in FIG. 1 has a plate shape. In FIG. 6, the backing plate 52 and the cooling water passage 55 are provided separately, but in FIG. 1, the cooling water passage 4 is provided in the backing plate 2. For this reason, in Example 1, a sputtering target can be reduced in size. However, the structure in which the cooling water channel 4 is provided inside the backing plate 2 is not essential, and may be a structure that is attached to the outside of the backing plate.

  FIG. 2 is a diagram illustrating a configuration of a sputtering apparatus including the sputtering target according to Embodiment 1 of the present invention. The sputtering apparatus is an ECR sputtering apparatus, and includes a plasma generation chamber-10 and a vacuum chamber-20.

  The plasma generation chamber 10 includes a coil 11 wound in multiple layers, and a voltage is applied to the coil 11 to generate a magnetic field, for example, a magnetic field of 875 G (Gauss) in the coil 11. Ions such as argon Ar are implanted into the plasma generation chamber 10. Further, a microwave, for example, 2.45 GHz is introduced into the plasma generation chamber-10. The energy of the magnetic field and the microwave satisfies the ECR condition, fc = qB / 2πm, and plasma is generated efficiently.

  Here, q is an ion charge amount, B is a magnetic flux, and fc is a microwave frequency.

  The vacuum chamber 20 is in a vacuum state, and includes a sputtering target including the target 1 described in the first embodiment, a wafer substrate 21, and a window 22.

  The window 22 draws out the plasma generated in the plasma generation chamber-10. A voltage is applied to the target 1 by a voltage source E. Since a negative voltage is applied to the target 1, the positive ion argon Ar in the plasma is accelerated by the electric field and collides with the target 1 to repel particles of the target 1.

  The wafer substrate 21 corresponds to the substrate of the present invention, and forms a film by attaching the repelled particles on the target 1.

  Thus, according to the ECR sputtering apparatus, the plasma generation and the sputtering function can be controlled independently. Sputtering with an ECR plasma source with a high ionization rate enables high-speed reactive film formation.

  Moreover, since the sputtering target of Example 1 is used for an ECR sputtering apparatus, the effect of the sputtering target of Example 1 can be acquired.

  FIG. 3 is a diagram showing the configuration of the sputtering target according to Example 2 of the present invention. The sputtering target according to Example 2 is characterized in that the shape of the cooling water channel 4a provided in the backing plate 2 is an annular shape having a substantially rectangular (rectangular) cross section. The cooling water channel 4 a is arranged so that one surface, that is, a surface corresponding to the long side of the cross-sectional rectangle is substantially parallel to the target cooling surface 1 b of the target 1.

  Thereby, since the opposing area of the surface corresponding to the long side of the cross-sectional rectangle of the cooling water channel 4a and the target cooling surface 1a increases, the target 1 can be cooled more effectively by the cooling water channel 4a.

  FIG. 4 is a diagram showing a configuration of a sputtering target according to Example 3 of the present invention. The sputtering target according to Example 3 is characterized in that the shape of the cooling water channel 4b provided in the backing plate 2 is an annular shape having a triangular cross section. In the case where the backing plate 2 has an annular shape with a triangular cross section, the cooling water channel 4 b is preferably a triangular cross section similar to the triangular shape of the cross section of the backing plate 2. This is because the entire backing plate 2 can be cooled more uniformly. The cooling water channel 4b is arranged so that one surface, that is, a surface corresponding to the hypotenuse of a triangular cross section is substantially parallel to the target cooling surface 1b of the target 1.

  Thereby, the opposing area of the surface equivalent to the hypotenuse of the cross-sectional triangle of the cooling water channel 4b and the target cooling surface 1b increases. When the same backing plate 2 having a triangular cross section is employed, the cross-sectional area of the triangular cooling water channel 4b (particularly, the cooling water channel 4b having a triangular shape similar to the backing plate 2) is the circular cross section shown in FIG. Since the cross-sectional area of the cooling water channel 4 having a rectangular cross section shown in FIG. 4 can be made larger, more cooling water can flow through the cooling water channel 4b. Therefore, in the third embodiment, the target 1 can be cooled more effectively than in the first and second embodiments.

  In the first to third embodiments, the ECR sputtering apparatus using the sputtering target of the first to third embodiments has been described. However, the present invention is not limited to this, and the first sputtering apparatus can be applied to a normal sputtering apparatus. Even when the sputtering target of Example 3 is used, the same effect can be obtained.

  The present invention can be used, for example, for forming a nitride thin film, an oxide thin film, a magnetic film, a ferrite, or the like.

1, 51 Target 1a Target sputtering surface 1b Target cooling surface 2, 52 Backing plate 3, 53 Bonding material 4, 4a, 4b, 55 Cooling water channel 10 Plasma generation chamber 11 Coil 20 Vacuum chamber 21 Wafer substrate 22 Window 54 Cooling block E Voltage source

Claims (5)

A sputtering target used for sputtering,
A target formed of a material to be sputtered and having an inner peripheral surface having a shape of a part of a conical surface;
A cooling water channel through which the cooling water flows, and a backing plate that cools the target by the cooling water channel,
The target has a uniform thickness corresponding to the distance between the inner peripheral surface that is the target sputtering surface to be sputtered and the target cooling surface that is the surface opposite to the inner peripheral surface and that is cooled by the cooling water channel. The sputtering target characterized by being. It further comprises a bonding material that joins the target and the backing plate,
The sputtering target according to claim 1, wherein the bonding material is interposed between the target and the backing plate with a uniform thickness.   3. The cooling water channel is formed in an annular shape inside the backing plate so as to face the target cooling surface over the entire circumference of the target cooling surface. The sputtering target described.   The sputtering target according to any one of claims 1 to 3, wherein the cooling water channel is formed so that one surface of the cooling water channel is parallel to the target cooling surface.   A sputtering apparatus provided with the sputtering target in any one of Claims 1-4.

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