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FEOL (Front End of Line: substrate process, the first half of wafer processing)
4. LDD formation

How a semiconductor wafer is made »

To avoid adverse effects (such as slower operation speed) of transistor miniaturization, LDDs (Lightly Doped Drains, low density impurity drains) are formed.
LDDs are also called extensions.

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

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

INDEX

4-1. n-LDD

p-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.


4-2. p-LDD

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.

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|

A+ A-

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