By What is oxide masking?
The use of the silicon dioxide layer (seeoxidation) on the surface of a silicon chip to provide a mask for selective processing of the chip.
Why silicon dioxide is commonly used as a diffusion mask?
The diffusivity of dopants like Boron and Phosphorus is much smaller in silicon dioxide compared to silicon. So silicon dioxide is widely used as a mask to selectively protect areas of silicon that require no doping.
What is oxidation diffusion?
Diffusion (sometimes referred to as annealing) is a thermal treatment used to move dopants, or impurities, and make dopants introduced by ion implantation electrically active. Oxidation forms a silicon oxide layer on the wafer’s surface, which acts as an insulating or protective layer over it.
How does oxide thickness increase with time?
Flux, F3, corresponds to the reaction of the oxidizing species with Si, to form a new oxide layer. This is a parabolic rate law, which predicts that as the oxide thickness increases, the time increases as the square of the thickness.
Why is wet oxidation faster than dry?
In case of wet oxidation where water is use instead of oxygen, the water molecule can dissociate at high temperatures to form hydroxide OH that can diffuse in the silicon faster than molecular O2. Therefore the wet oxidation process has a significantly higher oxidation rate than the dry oxidation.
Which gas is used in dopant diffusion?
diborane
A common gaseous p dopant is diborane. Dopants are used in epitaxial deposition, diffusion and ion implantation.
What happens to silicon when exposed to oxygen?
The surface of lumps of silicon is protected by a very thin layer of silicon dioxide, SiO2. After this, reaction with oxygen in the air gives silicon dioxide. At temperatures above about 1400°C, silicon reacts with nitrogen, N2, in the air as well as oxygen, to form the silicon nitrides SiN and Si3N4.
What is the difference between dry oxidation and wet oxidation?
Dry oxidation means, it is oxidized with oxygen. Wet oxidation means the silicon is oxidized with stream or water vapor.
What is the advantage of rapid thermal oxidation?
Short processing times, high heating rates, high purity of process gases, and the possibility of quickly changing over between various process gases are those advantages of RTP that allow this approach to be viewed as a promising way for manufacturing submicron ICs.
What are the most critical parameters to control oxide?
For a chosen oxidant species the oxide growth rate usually is controlled by the temperature. Additionally, it is possible to vary the hydrostatic pressure in the reaction chamber, if the oxidation system offers such possibilities.
What is oxidation in CMOS?
5 Oxidation. Oxidation is a process which converts silicon on the wafer into silicon dioxide. The chemical reaction of silicon and oxygen already starts at room temperature but stops after a very thin native oxide film.
What are p and n-type semiconductors?
p-n junction diodes are made up of two adjacent pieces of p-type and n-type semiconducting materials. p-type and n-type materials are simply semiconductors, such as silicon (Si) or germanium (Ge), with atomic impurities; the type of impurity present determines the type of the semiconductor.