Read text B carefully paying attention to the words in bold type

Answer the following questions to text A.

Decide whether the following statements are true or false according to text A.

1. The early Penning discharges used magnetic fields parallel to the sputtering target surface.

2.Magnetron sources in a “closed-loop” pattern can be used to confine electrons near the surface in a closed pattern.

3. These confined electrons generate low- density plasma near the surface.

4. There was a sputtering source known as “S-gun”.

5. A planar magnetron sputtering source was developed by Charlie Chaplin.

6.The “sputter-gun” and the “S-gun” mean the same.

1. Are the trajectories of electrons influenced by magnetic fields?

2.What magnetic fields did the early Penning discharges use?

3.Do confined electrons generate high-density plasma near or on the surface?

4.What is a “Sputter-gun”?

5.What are Chapin, Chopin, Chaplin known for?

6.What are the advantages of planar magnetron?

7.What are the disadvantages of the early magnetron sources?

8.Are magnetrons used in everyday life?

B. Coating Structure and Morphology at an Early Stage

One of the disadvantages of these early magnetron sources was that the plasma was effectively trapped near the surface of the sputtering target. This meant that the reactive gases could not be dissociated effectively near the substrate and the ion bombardment of the substrate was low resulting in poor quality films. The problem was partially solved by adding auxiliary ionization sources or using RF. The invention of the unbalanced magnetron (разбалансированныймагнетрон) in 1986 offered a better solution. The unbalanced magnetron allows some electrons to escape from the confining field and create plasma in regions away from the target surface. When the escaping magnetic field is linked to other unbalanced magnetron sources (north to south poles), the plasma generation area can be significantly increased.

With the invention of the scanning electron microscope (SEM), the growth morphology of the deposited coating could be examined. The relationship between the substrate temperature, kinetic energy of the ions and the deposition rate has been summarized in various structure zone models. In 1977 Thornton published a ‘structure zone model’ (SZM) for evaporated coatings. The diagram is known as the ‘ Thornton Diagram’ and illustrates the relationship between the coating morphology, the deposition temperature and the pressure in the sputtering chamber. The sputtering pressure determines the flux and energy of the reflected high-energy neutrals from the sputtering cathode. The structure zone model was further refined.

Дата добавления: 2014-12-26