Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion A: Impurity diffusion in semiconductor essentially needs very high temperature. Reason R: Diffusivity of impurity atoms is negligibly small at room temperature. In the light of the above statements, choose the most appropriate answer from the options given below
Analyzing Assertion A: Impurity Diffusion Temperature
Assertion A states that impurity diffusion in semiconductors essentially requires very high temperatures. Diffusion is the process where atoms move from a region of higher concentration to lower concentration. In semiconductors, this movement requires sufficient thermal energy for the impurity atoms to overcome the lattice potential barriers and move into new positions. Therefore, higher temperatures provide this necessary energy, making the statement correct.
Analyzing Reason R: Diffusivity at Room Temperature
Reason R states that the diffusivity of impurity atoms is negligibly small at room temperature. Diffusivity (D) is a measure of the rate of diffusion and is highly dependent on temperature, typically following the relation D = D0 exp(-Ea/kT), where Ea is the activation energy. At room temperature (low T), the exponential term is very small, resulting in very low diffusivity. This statement is also correct.
Connecting Reason R to Assertion A
Reason R explains why Assertion A is true. Because the diffusivity is very low at room temperature (Reason R), significantly higher temperatures are needed to achieve a practical rate of impurity diffusion in semiconductors (Assertion A). Thus, Reason R provides the correct explanation for Assertion A.
Conclusion
Both Assertion A and Reason R are correct statements, and Reason R correctly explains Assertion A.
Important Questions from Semiconductor Process Flow
A. For impurity diffusion in semiconductor, concentration gradient is the only essential requirement.
B. Annealing is a mandatory step after ion-implantation.
C. Wet etching is normally anisotropic
D. High temperature is required for the growth of $SiO_2$ because oxidation reaction takes place at high temperature
E. Bird's beak formation is a characteristic of LOCOS isolation
Choose the correct answer from the options given below:
Arrange the given process steps in sequence for self-aligned gate formation.
A. Thermal oxidation to grow gate oxide.
B. Polysilicon deposition
C. Photolithography using gate mask
D. Etching of polysilicon and oxide
E. Source/drain diffusion
Choose the correct answer from the options given below:
- Match the LIST-I with LIST-IIChoose the correct answer from the options given below:
LIST-I LIST-II A. Shallow trench isolation (STI) I. Low static power dissipation B. Junction isolation II. High static power dissipation C. CMOS technology III. High component density D. Bipolar IC technology IV. Low component density - In particle beam lithography, the resolution depends upon :
When silicon dioxide of thickness d is grown, the Silicon consumed is :
