Self-aligned double-patterning SADP scheme

3 Self-aligned double-patterning (SADP) scheme 

Eigure 17.19 shows the processing scheme for the SADP scheme. The process scheme begins with the first lithographic masking exposure to create resist images on a HM that is disposed on top of suitable semiconductor substrates such 

The next step is the conformal deposition of a spacer material, oftentimes a nitride film, over the HM patterns. A second etch step, called the etch hack step, is implemented in such a way as to remove the thickness of the spacer material corresponding to the thickness only on the horizontal surfaces, while leaving intact 

Step 1. Lithography 1. The first resist pattern is created. 

Step 4. Etch back. The top of the nitride spacer and the HMs are removed. 

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