7. Etch System - What is an Etch System?
An etch system shapes the thin film into a desired patterns using liquid chemicals, reaction gases or ion chemical reaction. An etch system is used in manufacturing lines for semiconductors and other electronic devices.
Fig. 7-1 shows the flow of the etching process.
(1) Etch System - Wet
The exposed portion is removed by using acid or alkali.
Wet Etch System Characteristics
- Inexpensive chemical liquids (etchant)
- Collectively process multiple wafers at the same time
- Isotropic etching
Using high vacuum plasma
Plasma is generated from the gas and the etched material is removed by chemical reaction and accelerated ions.
Dry Etch System Characteristics
- Excellent in microfabrication and anisotropic
- Plasma is used in the Etch System
- More expensive than wet etching
What is plasma?
Plasma is a group of charged particles that is kept almost electrically neutral as a whole. The ions with a positive charge and electrons with a negative charge are distributed equally in an ionized state. Various plasma methods of the dry etch system are shown below.
What is ECR?
ECR stands for Electron Cyclotron Resonance. Applying a magnetic field to a vacuum system starts a rotational motion of electrons called cyclotron motion centered at the magnetic field lines in the magnetic field. When a microwave with frequency ω matching the rotation speed is made incident, energy resonance occurs between the cyclotron motion and electric field, and the electric field energy is absorbed by the electrons. This is called electron cyclotron resonance. It effectively accelerates electrons and can apply a large amount of energy. The plasma that is generated with the energy applied in this way is called ECR plasma. The microwave is 2.45GHz, and the corresponding resonance magnetic field is 875 Gauss.
Introducing the product lineup of dry etch systems
Next generation devices at 20nm and below require double-patterning, 3D (three-dimensional) structures, and complex, high-precision processes that include protective layer formation and finishing techniques for new materials.
Conductor Etch System M-8000 Series is utilized for hard mask and silicon etching for 32nm and beyond. Hitachi High-Tech developed new process flows, such as double patterning and new material etch processes such as high-k dielectric/metal gate through JDP (Joint Development Program) with device makers and material / tool suppliers.
Low temperature etch technology and TM (Time Modulation) bias technology together with the ECR (Electron Cyclotron Resonance) high density plasma source provide for a clean process, superior trench profiles without sidewall residue, and excellent productivity.
Hitachi High-Tech provides the following production support programs with the concept of "achievement of total solution services to enhance the value-added equipment and to reduce operation cost."