Tech Team · Kintek Solution

Sputtering targets are critical components in thin-film deposition processes, and their specifications are far more stringent than those of traditional materials. These specifications include size, flatness, purity, impurity content, density, grain size, and defect control. Additionally, they have high or special requirements such as surface roughness, resistance, grain size uniformity, composition and tissue uniformity, oxide content and size, magnetic permeability, ultra-high density, and ultra-fine grains. The shape of sputtering targets can vary, with flat and cylindrical being the most common, and their design often includes a metallic holder with water cooling channels. The quality of these targets is paramount, as impurities, larger grains, or rough surfaces can lead to defects in the thin film. Specific materials, like Platinum (Pt) sputtering targets, have their own unique set of specifications, including material type, atomic weight, thermal conductivity, melting point, and more.

Key Points Explained:

1. Size and Shape:

   • Flat Targets: Easier and cheaper to replace, commonly used in various sputtering systems.
   • Cylindrical/Ring-Shaped Targets: Required for specific chamber designs, more expensive due to their complex shape.
   • Metallic Holder: Targets are often bonded to a metallic holder that includes water cooling channels to manage heat during the sputtering process.

2. Material Quality:

   • Purity: High purity is essential to prevent defects in the thin film. Impurities can lead to poor film properties.
   • Grain Size: Smaller grains are preferred as larger grains can negatively impact the film's properties.
   • Surface Condition: Smooth surfaces are crucial; rough surfaces can cause defects in the film.

3. Physical and Chemical Properties:

   • Density: Ultra-high density is often required to ensure the target material's integrity during the sputtering process.
   • Defect Control: Minimizing defects is critical to prevent contamination and ensure high-quality thin films.
   • Composition and Tissue Uniformity: Uniform composition and tissue structure are necessary for consistent film deposition.

4. Special Requirements:

   • Surface Roughness: Low surface roughness is vital to avoid film defects.
   • Resistance: Specific resistance levels may be required depending on the application.
   • Grain Size Uniformity: Uniform grain size ensures consistent film properties.
   • Oxide Content and Size: Controlled oxide content and size are necessary to maintain film quality.
   • Magnetic Permeability: Certain applications may require specific magnetic properties.
   • Ultra-Fine Grains: Extremely fine grains are often necessary for high-performance applications.

5. Specific Material Example - Platinum (Pt) Sputtering Targets:

   • Material Type: Platinum
   • Symbol: Pt
   • Atomic Weight: 195.084
   • Atomic Number: 78
   • Color/Appearance: Metallic Gray
   • Thermal Conductivity: 72 W/m.K
   • Melting Point: 1,772°C
   • Coefficient of Thermal Expansion: 8.8 x 10-6/K
   • Theoretical Density: 21.45 g/cc
   • Z Ratio: 0.245
   • Sputter: DC
   • Max Power Density: 100 Watts/Square Inch
   • Type of Bond: Indium, Elastomer
   • Additional Comments: Platinum alloys with other metals, and films made from it are soft with poor adhesion.

6. Effectiveness Factors:

   • Composition: The material's composition plays a significant role in its effectiveness.
   • Type of Ions: The type of ions used to break down the target material can affect the sputtering process and the resulting film quality.

In summary, sputtering targets must meet a wide range of stringent specifications to ensure high-quality thin-film deposition. These specifications cover physical dimensions, material quality, and various special requirements that are crucial for the performance and reliability of the sputtering process. Specific materials, like Platinum, have their own unique set of properties that must be carefully controlled to achieve the desired film characteristics.

Summary Table:

Specification	Details
Size and Shape	Flat or cylindrical shapes; metallic holders with water cooling channels.
Material Quality	High purity, small grain size, smooth surfaces.
Physical Properties	Ultra-high density, defect control, uniform composition.
Special Requirements	Low surface roughness, controlled oxide content, ultra-fine grains.
Platinum (Pt) Example	High thermal conductivity, melting point: 1,772°C, theoretical density: 21.45 g/cc.

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