When we deposited a Bi2Te3 thin film in d.c. sputter system the morphology of surface vary with many parameters what are they as your knowledge in d.c. sputter deposition.
Sputtering is complex process, so many valuables may influence thin film surface morphology. Moreover, many of these variables are dependent on each other. In particular case dealing with telluride material, I would like to mention: substrate/thin film temperature, substrate biasing, cathode – substrate geometry, substrate structure, applied power, working gas type, working gas pressure, target structure, magnet assembly…
Substrate (or thin film) temperature – will be important especially if this temperature is close to glass transition temperature or crystallization temperature. However, its importance is also with respect to positions of maxima of nucleation and crystal growth, where e.g. creation of nuclei (“seeding”) may take place.
Substrate biasing – causes ion bombard of thin film and thus thin film modification.
Cathode – substrate geometry – involves distance and orientation of cathode and substrate; influences growth of thin film.
Substrate structure – e.g. substrate roughness may influence thin film growth mode or enable crystallization.
Applied power, working gas type, working gas pressure – influence deposition rate and thus energy and energy distribution of deposited species, which influences growth of thin film.
Target structure – may influence deposited species type (atoms/clusters, type of clusters, …) and consequently growth of thin film.
Magnet assembly – magnet assembly is usually fixed, however magnet assembly adjustment may strongly influence plasma-target interaction and thus whole process.
As written above, many of these variables are dependent on each other, e.g. deposition rate will be influenced by applied power, working gas type, working gas pressure, … On the other hand, deposition rate influences heating of substrate (and may influence re/crystallization) and target (and may change sputtering coefficients or even allow evaporation of volatile fractions).
Sputtering is complex process, so many valuables may influence thin film surface morphology. Moreover, many of these variables are dependent on each other. In particular case dealing with telluride material, I would like to mention: substrate/thin film temperature, substrate biasing, cathode – substrate geometry, substrate structure, applied power, working gas type, working gas pressure, target structure, magnet assembly…
Substrate (or thin film) temperature – will be important especially if this temperature is close to glass transition temperature or crystallization temperature. However, its importance is also with respect to positions of maxima of nucleation and crystal growth, where e.g. creation of nuclei (“seeding”) may take place.
Substrate biasing – causes ion bombard of thin film and thus thin film modification.
Cathode – substrate geometry – involves distance and orientation of cathode and substrate; influences growth of thin film.
Substrate structure – e.g. substrate roughness may influence thin film growth mode or enable crystallization.
Applied power, working gas type, working gas pressure – influence deposition rate and thus energy and energy distribution of deposited species, which influences growth of thin film.
Target structure – may influence deposited species type (atoms/clusters, type of clusters, …) and consequently growth of thin film.
Magnet assembly – magnet assembly is usually fixed, however magnet assembly adjustment may strongly influence plasma-target interaction and thus whole process.
As written above, many of these variables are dependent on each other, e.g. deposition rate will be influenced by applied power, working gas type, working gas pressure, … On the other hand, deposition rate influences heating of substrate (and may influence re/crystallization) and target (and may change sputtering coefficients or even allow evaporation of volatile fractions).
Power used duraing sputtering process may also have an effect. The lattice mismatch between the substrate to the film material may also have affect the morphology. Moreover the above answers are also very important.
I agree with all of you but could any one of you can give me some equation that determine the answer?
Jain Gutwirth written well about the parameters that affects the film properties.
Also you can reach the attachment and read all the equation related to the sputtering. I hope it will help you.
As I wrote above, due to complex character process, there are no equations connecting deposition parameters and thin film roughness as far as I know. However, some data dealing with sputtering yields (or deposition rates) can be found. On the other hand Sb2Te3 thin films have been studied due to its phase-change properties related to the data storage or thermoelectric properties thus You may be able to find some hints for your research.
If You want to setup your own experiment, the best way is to fix some variables at the beginning e.g.:
Working gas type – choose Argon
Substrate structure – choose some standard substrate – e.g. Si or microscope slides
Target structure – prepare some unified targets
Substrate biasing – choose no biasing
Cathode – substrate geometry and magnet assembly – at the beginning fix some common configuration which allows You to reach acceptable deposition rates and thickness homogeneity, subsequently use it as a variable (namely target – substrate distance)
Substrate (or thin film) temperature – fix the temperature at the beginning depending on required nature of thin films (amorphous or crystalline)
Applied power, working gas pressure – use them as a variables
One remark – annealing of thin films after deposition also strongly influences surface morphology, especially when amorphous thin films undergo crystallization.
-INCIDENCE ANGLE. With different incidence angles you can get some shadowing effects. You can also ROTATE THE TARGET and grow interesting spiral structures this way or do alternate layers at different angles.
-Anything that affects the KINETIC ENERGY the bombarding atoms. This will be a function of total pressure, distance to substrate, target voltage, plasma density, etc...
-Other "ENERGY" inputs that alter film growth, such as substrate temperature, substrate bias, etc...
-DEPOSITION TIME and FILM THICKNESS. The film morphology will evolve over time.
There is no simple analytic equation, however you can break down the machine parameters of your coater to particle fluxes and their angular/energy distributions at the substrate. Thereby, you get a description, which is independent from your actual coater design. Possible simulation methods are "Direct Simulation Monte Carlo" (DSMC) for neutral particle transport or "Particle in Cell Monte Carlo" (PIC-MC) if you also want to include the plasma discharge dynamics. Both methods are rather computationally expensive and require a multicore or HPC computing system. If you have the flux-, energy-, and angular distributions at the substrate, you can feed that information into atomistic film growth methods (e. g. kinetic Monte Carlo or Molecular Dynamics). The availability of validated growth models is actually limited to certain materials, but research in this area is going on.
Dear James,
The tool that I use was built by my own so that I want to know which parameters that would effects the surface morphology.
Till now I find that the pressure effects on surface morphology as well as gas flow rate
In addition to the power
Working gas pressure, substrate temperature, substrate biasing, target structure are parameters affect the structure. Also Composition of the target (Purity), Distance between the target and substrate, Deposition time all are affect the morphology of the film.
Surface morphology can be varied depending on working gas composition, sputtering power, target to substrate distance, substrate heating condition and so on.
- Badges
- Science method