Cuestionario: Wafer Etching Fundamentals — 11 preguntas

1. What is the primary function of etching in wafer fabrication?

A. To deposit insulating material across the wafer surface

B. To expose the wafer by removing all photoresist

C. To remove material uniformly or define a localized microcircuit pattern

D. To measure the thickness of each deposited layer

Answer: (C)

Explicación

Etching removes material either uniformly across a wafer or locally according to a pattern, allowing microcircuit features to be delineated.

2. What is the primary role of etching in semiconductor fabrication?

A. To measure the thickness of thin films

B. To deposit material onto the wafer surface

C. To clean the wafer surface before processing

D. To remove material uniformly or locally to create patterns

Answer: (D)

Explicación

Etching's main role is to remove material either uniformly or locally to delineate microcircuit patterns, which is essential for creating semiconductor components.

3. How do etching and photolithography work together during semiconductor fabrication?

A. Etching defines the protective pattern, and photolithography deposits material into the openings

B. Etching deposits polysilicon, and photolithography converts it into a passivation layer

C. Photolithography defines a protective pattern, and etching creates openings in the exposed material

D. Photolithography removes uncovered oxide, and etching develops the photoresist pattern

Answer: (C)

Explicación

Photolithography establishes the protective pattern, while etching removes exposed material to form openings for diffusion, implantation, and other semiconductor structures.

4. What is the main purpose of etching in semiconductor manufacturing?

A. To clean the wafer surface from contaminants

B. To remove material uniformly or locally to create patterns

C. To oxidize the wafer surface for insulation

D. To deposit material onto the wafer surface

Answer: (B)

Explicación

Etching is primarily used to remove material either uniformly or locally to delineate microcircuit patterns, which is essential for device fabrication.

5. What fundamentally distinguishes wet chemical etching from dry etching?

A. Wet etching transfers momentum from plasma ions, whereas dry etching dissolves material in a liquid

B. Wet etching patterns photoresist directly, whereas dry etching develops the photoresist in a solvent

C. Wet etching deposits material from a gas, whereas dry etching removes material with ultraviolet light

D. Wet etching dissolves material chemically, whereas dry etching removes it through ionized-gas momentum transfer

Answer: (D)

Explicación

Wet etching uses a liquid chemical to dissolve material or convert it into a soluble compound. Dry etching uses momentum transfer from ionized gases in a plasma.

6. What is the primary function of dry etching equipment in semiconductor fabrication?

A. To dissolve materials in a liquid chemical solution

B. To clean the wafer surface with chemical solvents

C. To transfer photolithographic patterns by removing unprotected oxide

D. To deposit thin films onto the wafer surface

Answer: (C)

Explicación

Dry etching equipment, such as a reactive ion etcher, is used to transfer patterns by removing oxide not protected by photoresist through plasma-based processes, unlike wet etching which dissolves materials chemically.

7. A fabrication step uses a plasma to remove uncovered oxide after photoresist patterning; which type of etching is being used?

A. Wet etching using a liquid chemical solvent

B. Dry etching using reactive or ionized gases

C. Mechanical etching using a polishing slurry

D. Thermal etching using localized wafer heating

Answer: (B)

Explicación

Dry etching uses gases, commonly in an ionized plasma, rather than the liquid chemicals used in wet chemical etching.

8. When does the system startup process typically begin after the operator has prepared the necessary connections and checked the system parameters?

A. Immediately after verifying nitrogen pressure and valve status

B. Once the wafer is loaded into the chamber and the recipe is selected

C. After pressing the green ON button and the System Start Up soft key, and waiting for the pumps to reach their operating speed

D. When the chamber pressure reaches the desired vacuum level

Answer: (C)

Explicación

The system startup begins after the operator presses the ON button, then the System Start Up soft key, and waits for the pumps, especially the turbo molecular pump, to reach its normal operating speed of 48,000 rpm, which takes about six minutes.

9. What is the main difference between wet and dry etching in semiconductor fabrication?

A. Wet etching dissolves material in a liquid chemical, while dry etching removes material through momentum transfer from plasma gases.

B. Wet etching is a faster process than dry etching, regardless of the material.

C. Wet etching uses plasma gases to remove material, whereas dry etching dissolves material in a solvent.

D. Wet etching is used only for oxide removal, while dry etching is used for resist stripping.

Answer: (A)

Explicación

Wet etching involves dissolving material in a liquid chemical, whereas dry etching removes material via momentum transfer from ionized gases in plasma. The key difference lies in the removal mechanism.

10. Who is credited with developing the dry-etching equipment used in semiconductor fabrication?

A. The engineers at Samco

B. The inventors of plasma technology

C. The manufacturers of reactive ion etchers

D. The researchers who discovered reactive ion etching

Answer: (A)

Explicación

The dry-etching equipment, specifically the reactive ion etcher, was developed by engineers at Samco, who designed it for precise material removal in semiconductor manufacturing.

11. What is a key consequence of using wet resist stripping in semiconductor fabrication?

A. It chemically dissolves the resist-coated wafer in a controlled manner.

B. It allows for selective removal of oxide layers.

C. It results in the complete removal of photoresist without affecting other materials.

D. It prevents contamination by removing all residues from the wafer surface.

Answer: (A)

Explicación

Wet resist stripping chemically dissolves the photoresist in a stripper solution, which is a controlled process. This method ensures complete removal of resist without damaging underlying layers, unlike dry methods that may be more selective or cause different effects.