A target assembly having a strengthened backing plate and a method of making the same

Abstract

This invention relates to a target assembly for enhancing backplate strength and its preparation method. The target assembly includes a target and a backplate. The backplate has an internal groove, the distance between the edge of the groove and the outer edge of the backplate is ≤1 / 5R, where R represents the radius of the outer edge of the backplate. The target has protrusions matching the groove. The groove and the protrusions are connected by welding. The groove is shaped like an inverted frustum, and the thickness gradient of the backplate increases along the sides of the inverted frustum. This invention can enhance the strength of the backplate, extend the service life of the target, and improve the target's resistance to deformation in high-temperature vacuum environments without increasing the overall height of the target assembly, thereby ensuring the stability and safety of the sputtering process.

Description

Technical Field

[0001] This invention relates to the field of target technology, specifically to a target assembly for enhancing backplate strength and its preparation method. Background Technology

[0002] Sputtering targets are core consumable materials in physical vapor deposition (PVD) processes. They typically employ a welded composite structure, consisting of two parts: the target (blank) that directly participates in sputtering and the backing plate that does not. The target is made of high-purity metal materials (such as aluminum, copper, titanium, tantalum, etc.), and its purity directly affects the performance of the thin film. The backing plate is usually made of high-strength aluminum alloy, copper alloy, or stainless steel. During sputtering, it provides mechanical support for the fragile target and performs electrical and thermal conductivity, as well as connecting and fixing it to the equipment cavity, preventing the target from warping or deforming under high temperature and high vacuum conditions.

[0003] As downstream industries demand higher production efficiency, sputtering targets are evolving towards longer lifespans. One method to extend target life is to increase target thickness, providing more sputterable material. However, when the total height of the target assembly is limited by the equipment cavity specifications and must remain constant, increasing the target thickness inevitably leads to a reduction in the thickness of the backplate. When the backplate is too thin, the structural strength of the target assembly decreases, making it highly susceptible to bending and deformation under the combined effects of high-temperature heat load and vacuum suction during sputtering. Deformation of the backplate can not only cause short circuits or arcing due to contact between the target and equipment components, but it can also affect the uniformity of the sputtering magnetic field, ultimately leading to a decrease in wafer coating quality or even scrapping. Therefore, the commonly used method to extend target life is to increase the thickness of the backplate. However, due to the limited cavity space of sputtering equipment, the total height of the target assembly is strictly limited. Directly increasing the backplate thickness leads to an increase in the total height, altering the spacing between the sputtering surface and the wafer, and the spacing between the sputtering surface and the magnet, severely impacting the normal use of the target.

[0004] Therefore, how to improve the service life of the target material without increasing the overall height of the target material assembly is a technical problem that needs to be solved. Summary of the Invention

[0005] To address the above problems, the present invention aims to provide a target assembly with enhanced backplate strength and its preparation method. Compared with the prior art, the present invention can enhance the strength of the backplate, extend the service life of the target, and improve the target's resistance to deformation in a high-temperature vacuum environment without increasing the total height of the target assembly, thereby ensuring the stability and safety of the sputtering process.

[0006] To achieve this objective, the present invention employs the following technical solution: In a first aspect, the present invention provides a target assembly for enhancing the strength of a backplate, the target assembly comprising a target and a backplate; The back plate has a groove inside, and the distance between the edge of the groove and the outer edge of the back plate is ≤1 / 5R, where R represents the radius of the outer edge of the back plate; The target material is provided with protrusions that match the groove; The groove and the protrusion are connected by welding; The groove is shaped like an inverted frustum, and the thickness gradient of the back plate increases on the side of the inverted frustum.

[0007] This invention, by setting grooves in the backplate and protrusions in the target material, achieves a higher thickness in the central region of the target material while maintaining the same overall height of the target assembly, thus ensuring a longer service life. Simultaneously, by thinning the edge region of the target material (which does not participate in sputtering), more thickness is provided for the backplate, ensuring a higher thickness in the edge region. This improves the overall strength of the backplate, particularly enhancing the deformation resistance of the edge support portion. This effectively prevents abnormal operation caused by backplate deformation under high-temperature vacuum conditions, ensuring the stability and safety of the sputtering process.

[0008] Preferably, the thickness at the center of the back plate is the minimum, and the thickness is 7~10mm, for example, it can be 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm or 10mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0009] Preferably, the thickness of the back plate is greatest at the outer edge, and the thickness is 8~20mm, for example, it can be 8mm, 10mm, 12mm, 14mm, 16mm, 18mm or 20mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0010] In this invention, by optimally controlling the thickness of the back plate at the center and the outer edge, it is possible to control it to have a structure that is thicker at the edges and thinner in the middle. This not only extends the service life of the target material but also improves the overall structural strength of the back plate and reduces the risk of deformation during welding and use.

[0011] Preferably, the radius of the larger end of the groove is 0.75~0.85R, for example, it can be 0.75R, 0.76R, 0.78R, 0.80R, 0.82R, 0.84R or 0.85R, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0012] Preferably, the radius of the small end of the groove is 0.45~0.55R, for example, it can be 0.45R, 0.46R, 0.48R, 0.50R, 0.52R, 0.54R or 0.55R, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0013] Preferably, the radius of the outer edge of the back plate is 400~600mm, for example, it can be 400mm, 450mm, 500mm, 550mm or 600mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0014] In this invention, by adopting an inverted frustum-shaped structure, the stress distribution can be optimized and the deformation resistance can be further improved compared with the conventional straight butt joint structure.

[0015] Preferably, the thickness of the target material outside the groove is 12-13 mm, for example, it can be 12 mm, 12.2 mm, 12.4 mm, 12.6 mm, 12.7 mm, 12.8 mm or 13 mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0016] Preferably, the inner surface of the groove is provided with threads.

[0017] Preferably, the thread is serrated.

[0018] Preferably, the depth of the thread is 0.5~1.5mm, for example, it can be 0.5mm, 0.6mm, 0.8mm, 1.0mm, 1.2mm, 1.4mm or 1.5mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] Preferably, the thread pitch is 0.4~0.6mm, for example, it can be 0.4mm, 0.42mm, 0.44mm, 0.46mm, 0.48mm, 0.5mm, 0.52mm, 0.54mm, 0.56mm, 0.58mm or 0.6mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] In this invention, by setting threads inside the groove and controlling the depth and spacing of the threads, the welded joint strength can be improved and the resistance to deformation can be enhanced.

[0021] Preferably, the material of the back plate includes aluminum alloy and / or copper alloy.

[0022] Preferably, the target material is made of any one or a combination of at least two of aluminum, titanium, tantalum, copper, nickel, tungsten, or silver.

[0023] In a second aspect, the present invention provides a method for preparing a target assembly as described in the first aspect of the present invention, the method comprising the following steps: S1, The backplate and the target material are machined to obtain a backplate with grooves and a target material with protrusions; S2, thread the welding surface of the groove to obtain the pre-treated back plate; S3, the pre-treated backplate and the target material containing protrusions are welded together to obtain the target material assembly.

[0024] Preferably, the machining method includes turning.

[0025] Preferably, the welding method includes brazing or diffusion welding.

[0026] Preferably, the brazing temperature is 100~300℃, for example, it can be 100℃, 120℃, 140℃, 160℃, 180℃, 200℃, 220℃, 240℃, 260℃, 280℃ or 300℃, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0027] Preferably, the temperature of the diffusion welding is 400~800℃, for example, it can be 400℃, 450℃, 500℃, 550℃, 600℃, 650℃, 700℃, 750℃ or 800℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] In this invention, by optimizing the control of the welding temperature, the hardness of the back plate can be further guaranteed and the resistance to deformation can be improved.

[0029] Compared with the prior art, the present invention has the following beneficial effects: The target assembly provided by this invention, through the cooperation of grooves and protrusions, can maintain a high thickness in the central region of the target while keeping the total height of the target assembly unchanged, thus ensuring a long service life for the target. At the same time, by thinning the edge region of the target (which does not participate in sputtering), thicker space is provided for the backplate, allowing the backplate to maintain a high thickness in the edge region. This improves the overall strength of the backplate, especially significantly enhancing the deformation resistance of the edge support portion. This effectively prevents abnormal use caused by backplate deformation under high-temperature vacuum conditions, ensuring the stability and safety of the sputtering process. Under optimal conditions, the target assembly provided by this invention can reduce the deformation of the backplate to below 0.4 mm. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the target assembly provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the target assembly provided in Comparative Example 1 of the present invention; 1-Backplate; 2-Target material. Detailed Implementation

[0031] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0032] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0033] Example 1 This embodiment provides a target material assembly for enhancing the strength of the backplate, such as... Figure 1 As shown, the target assembly includes a target 2 (titanium) and a backplate 1 (copper alloy).

[0034] The back plate 1 has a groove inside, and the distance between the edge of the groove and the outer edge of the back plate 1 is 1 / 5R, where R represents the radius of the outer edge of the back plate 1. The groove is shaped like an inverted frustum, and the thickness of the back plate 1 increases gradually along the side of the inverted frustum. The thickness is smallest at the center of the back plate 1, with a thickness of 8mm, and largest at the outer edge of the back plate 1, with a thickness of 12.7mm. The radius of the large end of the groove is 0.8R, the radius of the small end of the groove is 0.5R, and the radius of the outer edge of the back plate 1 is 500mm. The inner surface of the groove is provided with threads, and the threads are serrated in shape. The depth of the threads is 1.0mm, and the spacing of the threads is 0.5mm.

[0035] The target material 2 is provided with a protrusion that matches the groove. The groove and the protrusion are connected by welding. The thickness of the target material 2 outside the groove is 12.7 mm.

[0036] This embodiment also provides a method for preparing the above-mentioned target material component, the method comprising the following steps: S1, the back plate 1 and the target material 2 are turned to obtain a back plate 1 with grooves and a target material 2 with protrusions; S2, thread the welding surface of the groove to obtain the pre-treated back plate 1; S3, the pretreated backplate 1 and the target material 2 containing protrusions are diffusion welded at a temperature of 750°C to obtain the target material assembly.

[0037] Example 2 This embodiment provides a target assembly for enhancing the strength of a backplate, the target assembly comprising a target (aluminum) and a backplate (copper alloy).

[0038] The back plate has a groove inside, and the distance between the edge of the groove and the outer edge of the back plate is 1 / 5R, where R represents the radius of the outer edge of the back plate. The groove is shaped like an inverted frustum, and the thickness of the back plate increases gradually along the side of the inverted frustum. The thickness is smallest at the center of the back plate (7mm) and largest at the outer edge (12.7mm). The radius of the large end of the groove is 0.75R, the radius of the small end of the groove is 0.45R, and the radius of the outer edge of the back plate is 400mm. The inner surface of the groove is threaded, the thread is sawtooth-shaped, the thread depth is 0.6mm, and the thread spacing is 0.4mm.

[0039] The target material is provided with a protrusion that matches the groove. The groove and the protrusion are connected by welding. The thickness of the target material outside the groove is 12.7 mm.

[0040] This embodiment also provides a method for preparing the above-mentioned target material component, the method comprising the following steps: S1, the back plate and the target are turned to obtain a back plate with grooves and a target with protrusions. S2, thread the welding surface of the groove to obtain the pre-treated back plate; S3, the pretreated backplate and the target material containing protrusions are diffusion welded at a temperature of 540°C to obtain the target material assembly.

[0041] Example 3 This embodiment provides a target assembly for enhancing the strength of a backplate, the target assembly comprising a target (nickel) and a backplate (copper alloy).

[0042] The back plate has a groove inside, and the distance between the edge of the groove and the outer edge of the back plate is 1 / 5R, where R represents the radius of the outer edge of the back plate. The groove is shaped like an inverted frustum, and the thickness of the back plate increases gradually along the side of the inverted frustum. The thickness is smallest at the center of the back plate (10mm) and largest at the outer edge (12.7mm). The radius of the large end of the groove is 0.85R, the radius of the small end of the groove is 0.55R, and the radius of the outer edge of the back plate is 600mm. The inner surface of the groove is threaded, the thread is sawtooth-shaped, the thread depth is 1.5mm, and the thread spacing is 0.6mm.

[0043] The target material is provided with a protrusion that matches the groove. The groove and the protrusion are connected by welding. The thickness of the target material outside the groove is 12.7 mm.

[0044] This embodiment also provides a method for preparing the above-mentioned target material component, the method comprising the following steps: S1, the back plate and the target are turned to obtain a back plate with grooves and a target with protrusions. S2, thread the welding surface of the groove to obtain the pre-treated back plate; S3, the pretreated backplate and the target material containing protrusions are brazed together at a temperature of 800°C to obtain the target material assembly.

[0045] Example 4 This embodiment provides a target assembly for enhancing the strength of the backplate. The only difference from Embodiment 1 is that the thickness at the center of the backplate is 4 mm.

[0046] Example 5 This embodiment provides a target assembly for enhancing the strength of the backplate. The only difference from Embodiment 1 is that the thickness at the center of the backplate is 15 mm.

[0047] Example 6 This embodiment provides a target assembly for enhancing the strength of the backplate. The only difference between this embodiment and the one in Embodiment 1 is that the radius of the small end is 0.2R.

[0048] Example 7 This embodiment provides a target assembly for enhancing the strength of the backplate. The only difference between this embodiment and the one in Embodiment 1 is that the radius of the small end is 0.7R.

[0049] Comparative Example 1 This comparative example provides a target assembly, such as... Figure 2 As shown, it includes a target material 2 and a back plate 1. The only difference from Example 1 is that the groove is cylindrical and the radius of the groove is 0.8R.

[0050] Deformation resistance test: The target material components prepared in the examples and comparative examples were measured. The measurement method was to use a coordinate measuring machine (CMM) to test the deformation of the back plate. First, the back plate was placed face up on a flat marble table. Then, the probe selected 4 measuring points in the cross direction of the edge of the back plate surface to confirm a plane P, that is, the edge of the back plate as the reference plane. The probe collected a point C in the center of the target material. The vertical distance from point C to plane P was calculated using three-dimensional coordinates to obtain the deformation of the back plate. The results are shown in Table 1.

[0051] Table 1 As can be seen from Table 1: (1) As can be seen from the data of Examples 1 to 3, the target assembly provided by the present invention can reduce the deformation of the back plate to less than 0.4 mm.

[0052] (2) As can be seen from the comparison between Example 1 and Examples 4-7, the present invention can further improve the anti-deformation effect by controlling the thickness at the center of the back plate and the radius at the small end.

[0053] (3) As can be seen from the comparison between Example 1 and Comparative Example 1, although Comparative Example 1 can also increase the thickness of the target material while keeping the total height of the target material assembly unchanged, the strength of the back plate is greatly reduced and the anti-deformation effect is worse.

[0054] In summary, this invention can enhance the strength of the backplate, extend the service life of the target, and improve the target's resistance to deformation in a high-temperature vacuum environment without increasing the overall height of the target assembly, thereby ensuring the stability and safety of the sputtering process.

[0055] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A target assembly for enhancing the strength of a backplate, characterized in that, The target assembly includes a target and a backplate; The back plate has a groove inside, and the distance between the edge of the groove and the outer edge of the back plate is ≤1 / 5R, where R represents the radius of the outer edge of the back plate; The target material is provided with protrusions that match the groove; The groove and the protrusion are connected by welding; The groove is shaped like an inverted frustum, and the thickness gradient of the back plate increases on the side of the inverted frustum.

2. The target assembly of claim 1, wherein, The thickness of the back plate is the smallest at the center, and the thickness is 7~10mm. Preferably, the thickness of the back plate is greatest at its outer edge, and the thickness is 8~20mm.

3. The target assembly of claim 1 or 2, wherein, The radius of the larger end of the groove is 0.75~0.85R; Preferably, the radius of the small end of the groove is 0.45~0.55R.

4. The target assembly of any of claims 1-3, wherein the target assembly comprises a plurality of target segments. The radius of the outer edge of the back plate is 400~600mm.

5. The target assembly of any of claims 1-4, wherein the target assembly comprises a plurality of target segments. The thickness of the target material outside the groove is 12~13mm.

6. The target assembly of any of claims 1-5, wherein the target material is a metal. The inner surface of the groove is provided with threads; Preferably, the thread is serrated.

7. The target assembly of claim 6, wherein, The depth of the thread is 0.5~1.5mm; Preferably, the thread pitch is 0.4~0.6mm.

8. The target assembly of any of claims 1-7, wherein, The backplate is made of aluminum alloy and / or copper alloy. Preferably, the target material is made of any one or a combination of at least two of aluminum, titanium, tantalum, copper, nickel, tungsten, or silver.

9. A method of manufacturing a target assembly according to any one of claims 1 to 8, characterized in that The preparation method includes the following steps: S1, The backplate and the target material are machined to obtain a backplate with grooves and a target material with protrusions; S2, thread the welding surface of the groove to obtain the pre-treated back plate; S3, the pre-treated backplate and the target material containing protrusions are welded together to obtain the target material assembly.

10. The method of claim 9, wherein, The machining method includes turning; Preferably, the welding method includes brazing or diffusion welding; Preferably, the brazing temperature is 100~300℃; Preferably, the temperature of the diffusion welding is 400~800℃.

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