Thin Film Technology: Deposition Methods and Techniques

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What is a characteristic of MOCVD that makes it suitable for optoelectronic devices?

Ability to deposit metal films
High deposition rate
Epitaxial growth for many optoelectronic devices with III-V compounds (correct)
Low process temperature

What happens when pressure is higher than in sputter deposition?

Less collision in the gas phase
No change in collision or ion bombardment
More ion bombardment on the substrate
More collision in the gas phase, less ion bombardment on the substrate (correct)

Why is RF plasma mode used in some CVD processes?

To reduce the process temperature
To increase the deposition rate
To avoid charge buildup for insulators (correct)
To improve the film quality

What determines the reaction rate in a CVD process?

Both transport and surface chemical reaction rate (D) Signup and view all the answers

What is the process temperature range for CVD?

100 - 400°C (C) Signup and view all the answers

What is the characteristic of film quality in MOCVD compared to LPCVD?

Poorer film quality (A) Signup and view all the answers

What is the effect of directional diffusion to the surface in a reactor?

Deterioration of the step coverage and filling (A) Signup and view all the answers

What is a problem associated with cold-wall reactors, in addition to poorer temperature control?

Gas convection (B) Signup and view all the answers

What is the role of the plasma in a PECVD process?

To transfer energy into the reactant gases, forming radicals (B) Signup and view all the answers

What is the typical frequency used for PECVD?

13.56MHz (C) Signup and view all the answers

What is the benefit of using RF-induced plasma in a PECVD process?

To increase the film density, composition, and step coverage (B) Signup and view all the answers

What happens to ks when the temperature increases?

ks increases (D) Signup and view all the answers

What is the effect of using N2 as the carrier gas for SiH4 in APCVD?

It increases the growth rate (B) Signup and view all the answers

What is the characteristic of hG limited deposition?

Very geometry sensitive (A) Signup and view all the answers

What is the purpose of using a horizontal reactor configuration in Si epitaxial deposition?

To achieve uniform film thickness across the wafer (C) Signup and view all the answers

What is the relationship between the partial pressure of the reactant gas and the growth rate?

The growth rate is directly proportional to the partial pressure (C) Signup and view all the answers

Why is high temperature used in Si epitaxial deposition?

To achieve high film quality (B) Signup and view all the answers

What is the typical thickness of a thin film?

Nanometer scale (A) Signup and view all the answers

What is the reaction equation for Si deposition from Silane at 650oC?

SiH4(g) → Si(s) + 2H2(g) (A) Signup and view all the answers

What is the purpose of using H2 in the reduction reaction?

To reduce the metal oxide to metal (D) Signup and view all the answers

What is the equation for the oxidation reaction of SiO2 deposition from silane and oxygen at 450oC?

SiH4(g) + O2(g) → SiO2(s) + 2H2(g) (B) Signup and view all the answers

What is the temperature range for the deposition of GaAs using (CH3)3Ga(g) and AsH3(g)?

650 – 750oC (C) Signup and view all the answers

What is the direction of flow in a reactor during mass transport?

Along the x-direction (B) Signup and view all the answers

What is the primary purpose of doping in CVD films?

To create a single-crystal film (D) Signup and view all the answers

How does the dopant concentration C vary with the partial pressure P of the dopant species at low growth rates?

C ∝ P (D) Signup and view all the answers

What is the process of unintentional doping in CVD film growth?

Out-diffusion of dopant from the substrate (D) Signup and view all the answers

What is the role of dissociation in the doping process?

To break down the dopant species into smaller particles (A) Signup and view all the answers

What is the source of auto-doping in CVD film growth?

The wafer front side, backside, or edges (D) Signup and view all the answers