Etching Outlines 1 Introduction 2 Etch Terminology 3

Etching

Outlines 1. Introduction 2. Etch Terminology 3. Wet Etch 4. Dry Etch

Introduction

In the last class, we have learned about photolithography where the pattern on the mask is transferred onto the wafer. Usually, the next step is etching where the unwanted area/layer is removed from the wafer surface.

EXAMPLE: GATE ETCH

Etch Terminology

Wet Etching

Chemical etching because there is chemical reaction taking place between the material that is going to be removed with the etchant solution.

Wet Etch Mechanism Let’s say we want to etch Si. O 2 with HF solution. 1. So we have an etchant material in the solution i. e. HF. And we want this HF molecules to be available on surface of Si. O 2 in order for chemical reaction – transport of etchant material to the surface of the material to be etched. 2. The etchant must react with the material to be etched – surface reaction. 3. The reaction product must be removed from the reaction site (otherwise, the surface reaction will stop) – transport of reaction product from the surface. How to achieve this?

Diffusion of etchant to the reaction surface Transport / removal of by product (Stirring)

2 -step process (anodic oxidation + etching)

Dry Etch

PLASMA ETCH

‘When you cannot withstand the hardship of seeking knowledge, then you have to withstand the shameful of stupidity’. ‘Apabila kamu tidak tahan lelahnya belajar, maka kamu harus tahan menanggung peritnya kebodohan’.

‘Ilmu itu bukan yang dihafal, tetapi yang memberi manfaat’. ‘Knowledge is not in the lines of the book, but in the heart of a man’.

‘True love is a love that you live with it and go through all the hardship with it’. ‘Cinta yang sejati adalah cinta yang dihidupi dan dimiliki untuk mengharungi pelbagai ujian’.