Gate Etching Process in VLSI

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What is the primary purpose of introducing Bottom Anti-Reflection Coatings (BARC) in the patterning process?

To reduce the line width

To improve the etch process

To avoid standing waves (correct)

To increase the device density

What is the effect of trimming on the device pitch?

It increases the device pitch

It decreases the device pitch

It has no effect on the device pitch (correct)

It improves the etch process

What is the main reason for using Optical Proximity Correction (OPC) in the patterning process?

To make uniform isolated and dense lines (correct)

To reduce the line width

To improve the etch process

To avoid standing waves

What is the primary function of Hard-Mask (HM) layers in the patterning process?

To improve the etch process Signup and view all the answers

Why is a second litho step necessary to increase the device density?

Because trimming does not improve the device pitch Signup and view all the answers

What is the origin of Optical Proximity Effects in the patterning process?

The limited amount of higher order spatial frequencies that can pass the lens Signup and view all the answers

What is the main advantage of using multiple exposure in the patterning process?

Enabling the creation of narrow lines at small pitches Signup and view all the answers

What is the purpose of overlaying a new image onto the old one in Self-Aligned Double Patterning (SADP)?

To align the new image with the old one Signup and view all the answers

What is the difference between the double line patterning and double trench approach?

The sequence of litho and etch steps Signup and view all the answers

What is a limitation of using multiple exposure in the patterning process?

Results in a high cost due to multiple litho and etch steps Signup and view all the answers

What is the purpose of using alignment marks in Self-Aligned Double Patterning (SADP)?

To align the new image with the old one Signup and view all the answers

What is the primary benefit of using Optical Proximity Correction (OPC) in the patterning process?

Making uniform isolated and dense lines Signup and view all the answers

What is the primary factor that determines the quality of CD control in a lithography process?

The percentage of dose deviation Signup and view all the answers

What is the maximum dose deviation that can be tolerated while maintaining CD control?

+/- 10% of the target CD Signup and view all the answers

What is the mechanism by which chemical amplification occurs in resist?

Through the action of a photo acid generator Signup and view all the answers

What is the purpose of the post-exposure bake in the lithography process?

To catalyze a chemical reaction using H+ Signup and view all the answers

What is the characteristic of a positive tone resist?

It becomes soluble in the developer when exposed Signup and view all the answers

What is the effect of chemical amplification in resist?

It reuses the acid generated multiple times Signup and view all the answers

What is the role of H+ in the chemical reaction during photo acid generator exposure?

To act as a catalyst for deprotection Signup and view all the answers

What is the primary cause of standing waves in photoresist?

Reflection of light in the transparent resist layer Signup and view all the answers

What is the purpose of using a protection group R in the photoresist?

To make the resin insoluble in the base Signup and view all the answers

What is the relationship between the wavelength of light and the total thickness of the resist layer?

The total thickness is equal to λ/4n Signup and view all the answers

What is the nature of the points of no displacement in a standing wave pattern?

Points of no displacement Signup and view all the answers

What is the primary purpose of using a post-exposure bake (PEB) step in the lithography process?

To facilitate the deprotection reaction Signup and view all the answers