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FEOL (Front End of Line: substrate process, the first half of wafer processing)
6. Source/drain

How a semiconductor wafer is made

Sources and drains are formed in n-MOS areas and p-MOS areas. The shapes of sources and drains are the same because usual transistors are symmetric. Which is a source or a drain is defined depending on the connection direction of the power supply.

P-source/drain: P-type impurities (e.g., B+) are implanted into p-MOS areas.

N-source/drain: N-type impurities (e.g., As+, P+) are implanted into n-MOS areas.

6-1. p-source/drain

p-source/drain

A resist pattern is formed to cover the n-MOS area, and p-type impurities (e.g., boron (B)) are implanted in the p-MOS area. After implantation, the resist pattern is removed.


6-2. n-source/drain

n-source/drain

A resist pattern is formed to cover the p-MOS area, and n-type impurities (e.g., phosphorus (P), arsenic (As)) are implanted in the n-MOS area. After implantation, the resist pattern is removed.

Process Flow

FEOL (Front End of Line: substrate process, the first half of wafer processing)
| 1. Isolation | 2. Well and channel formation | 3. Gate oxidation and gate formation
| 4. LDD formation | 5. Side wall spacers | 6. Source/drain | 7. Silicide | 8. Dielectric film |
9. Contact holes |

BEOL (Back End of Line: interconnect process, the second half of wafer processing)
| 10. Metal-1 | 11. Metal-2 |

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