Microfabrication technologies
MICRO-331
Question for SLT#3
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Description
Here are the 6 questions to prepare for the SLTl#3 session scheduled for next week. They are related to the topics of CVD and PVD, everything related to thin film deposition.
Please prepare the possible answers by consulting the MOOC and any other public available source. Each of you may be asked to present your solution path in your respective group, unless you opted out. If you have questions, please send first your thoughts on ED stem.
3.1
Describe the basic principle of chemical vapor deposition (CVD) deposition technique and list the types of CVD processes. List some typical materials that are good candidates for CVD. Discuss the two different growth regimes in a CVD process by using a graphical representation. What is the influence of the temperature? How does the graph log(tfilm) vs. 1/T change with pressure variation?
3.2
Silicon nitride Si3N4 (or more generally SixNy) is a widely used material in the fabrication of integrated electronics and MEMS devices as cantilevers and nano-membranes (see also lecture Prof. A. Radenovic), dielectric material (MEMS switches), and for the LOCOS process. What is the particular property of Si3N4 that makes is special? Si3N4 can be deposited with CVD processes, but also with Atomic Layer Deposition (ALD). Which are the main differences between CVD and ALD processes?
3.3
Diamond is usually used as a heat sink for high-power laser diodes and transistors due to its unique combination of properties: diamond is a hard, chemically inert material, with a high thermal conductivity, but negligible electrical conductivity. Explain which CVD method and the conditions used for the diamond deposition. Compare silicon dioxide (SiO2) films made by CVD and by thermal oxidation. In which application is more suitable to use thermally grown SiO2 and why?
3.4
Besides SiO2, Al2O3 (alumina) is a dielectric material used in transistor fabrication. Assume you must deposit an ~ 30 nm thick layer of Al2O3 on a non-flat substrate with some 3D surface profile. Which deposition method can you use? Find solutions from both PVD and CVD methods, and compare them from the perspectives of deposition principle, temperature, film quality, and step coverage.
3.5
The simplest method to deposit a thin film on a surface is the physical vapor deposition (PVD) based on evaporation. Describe the basic principles and system design of a PVD based on evaporation (with Joule heating and e-beam). What materials are typically used, and what materials are difficult or impossible to consider? Why do we sometimes use a planetary wafer system?
3.6
Sputtering using a plasma with charged Ar+ ions to bombard a target and deposit its atoms on a nearby substrate. Describe the basic principles and system design of the three sputter methods: DC, RF, and magnetron. What are the key differences among these methods? What are the advantages and disadvantages of each method?
Please prepare the possible answers by consulting the MOOC and any other public available source. Each of you may be asked to present your solution path in your respective group, unless you opted out. If you have questions, please send first your thoughts on ED stem.
Describe the basic principle of chemical vapor deposition (CVD) deposition technique and list the types of CVD processes. List some typical materials that are good candidates for CVD. Discuss the two different growth regimes in a CVD process by using a graphical representation. What is the influence of the temperature? How does the graph log(tfilm) vs. 1/T change with pressure variation?
3.2
Silicon nitride Si3N4 (or more generally SixNy) is a widely used material in the fabrication of integrated electronics and MEMS devices as cantilevers and nano-membranes (see also lecture Prof. A. Radenovic), dielectric material (MEMS switches), and for the LOCOS process. What is the particular property of Si3N4 that makes is special? Si3N4 can be deposited with CVD processes, but also with Atomic Layer Deposition (ALD). Which are the main differences between CVD and ALD processes?
3.3
Diamond is usually used as a heat sink for high-power laser diodes and transistors due to its unique combination of properties: diamond is a hard, chemically inert material, with a high thermal conductivity, but negligible electrical conductivity. Explain which CVD method and the conditions used for the diamond deposition. Compare silicon dioxide (SiO2) films made by CVD and by thermal oxidation. In which application is more suitable to use thermally grown SiO2 and why?
3.4
Besides SiO2, Al2O3 (alumina) is a dielectric material used in transistor fabrication. Assume you must deposit an ~ 30 nm thick layer of Al2O3 on a non-flat substrate with some 3D surface profile. Which deposition method can you use? Find solutions from both PVD and CVD methods, and compare them from the perspectives of deposition principle, temperature, film quality, and step coverage.
3.5
The simplest method to deposit a thin film on a surface is the physical vapor deposition (PVD) based on evaporation. Describe the basic principles and system design of a PVD based on evaporation (with Joule heating and e-beam). What materials are typically used, and what materials are difficult or impossible to consider? Why do we sometimes use a planetary wafer system?
3.6
Sputtering using a plasma with charged Ar+ ions to bombard a target and deposit its atoms on a nearby substrate. Describe the basic principles and system design of the three sputter methods: DC, RF, and magnetron. What are the key differences among these methods? What are the advantages and disadvantages of each method?