# Ablation of Copper Metal Films by Femtosecond Laser Multipulse Irradiation

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## Abstract

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## 1. Introduction

## 2. Theoretical Background

#### 2.1. Two Temperature Model

#### 2.2. Dynamic Thermal Properties

#### 2.3. Dynamic Optical Properties

## 3. Results and Discussion

## 4. Conclusions

## Author Contributions

## Conflicts of Interest

## Abbreviations

TTM | Two Temperature Model |

CE | Coulomb Explosion |

FTAE | Fast Thermal Accumulation Effect |

MD | Molecular Dynamics |

## References

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**Figure 1.**Reflectivity and absorption coefficient versus electron temperature. Note that the x-axis starts at 300 K.

**Figure 2.**Evolution of electron and lattice temperature as a function of time during the irradiation by 10 ${\mathrm{J}/\mathrm{cm}}^{2}$: (

**a**) 5 pulses and (

**b**) 10 pulses with 1.5 ps ($\frac{2}{3}$ THz) of separation time (repetition rate). Lattice temperature (${T}_{l}$) versus time and position into a copper sample for an absorbed fluence of 10 ${\mathrm{J}/\mathrm{cm}}^{2}$: (

**c**) 5 pulses and (

**d**) 10 pulses with 1.5 ps ($\frac{2}{3}$ THz) of separation time (repetition rate). d, ${t}_{eq}$ and ${T}_{\mathrm{c}}$ represent ablation depth, time equilibrium and critical temperature, respectively. ${T}_{\mathrm{c}}=7696$ K. TTM: Two Temperature Model.

**Figure 3.**Time dependence of the calculated electron (solid line) and lattice (dash line) temperature with varying pulse number at a fluence of 60 ${\mathrm{J}/\mathrm{cm}}^{2}$ and 1 ps (1 THz) of separation time (repetition rate).

**Figure 4.**Time dependence of the calculated electron (solid line) and lattice (dash line) temperatures with varying separation time ${t}_{sep}$ at a fluence of 1 ${\mathrm{J}/\mathrm{cm}}^{2}$ and four pulses.

**Figure 5.**The time dependence of the calculated electron (solid line) and lattice (dash line) temperatures at different laser fluences with 4 pulse and 1 ps (1 THz) of separation time (repetition rate).

**Figure 7.**The ablation rate as a function of fluence at different pulse numbers with ${t}_{sep}=1.5$ ps ($\frac{2}{3}$ THz repetition rate).

Fluence (${\mathbf{J}/\mathbf{cm}}^{2}$) | N = 1 | N = 2 | N = 3 | N = 4 | N = 5 |
---|---|---|---|---|---|

Ablation Depth (nm) | |||||

1 | 21 | 78 | 102 | 116 | 122 |

5 | 189 | 272 | 314 | 332 | 348 |

6 | 268 | 438 | 503 | 556 | 575 |

10 | 357 | 532 | 611 | 664 | 671 |

20 | 509 | 720 | 802 | 861 | 871 |

30 | 653 | 888 | 997 | 1067 | 1070 |

50 | 883 | 1175 | 1307 | 1394 | 1398 |

60 | 931 | 1222 | 1357 | 1439 | 1447 |

100 | 1080 | 1367 | 1485 | 1566 | 1575 |

200 | 1547 | 1927 | 2096 | 2192 | 2216 |

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**MDPI and ACS Style**

Abdelmalek, A.; Bedrane, Z.; Amara, E.-H.; Sotillo, B.; Bharadwaj, V.; Ramponi, R.; Eaton, S.M.
Ablation of Copper Metal Films by Femtosecond Laser Multipulse Irradiation. *Appl. Sci.* **2018**, *8*, 1826.
https://doi.org/10.3390/app8101826

**AMA Style**

Abdelmalek A, Bedrane Z, Amara E-H, Sotillo B, Bharadwaj V, Ramponi R, Eaton SM.
Ablation of Copper Metal Films by Femtosecond Laser Multipulse Irradiation. *Applied Sciences*. 2018; 8(10):1826.
https://doi.org/10.3390/app8101826

**Chicago/Turabian Style**

Abdelmalek, Ahmed, Zeyneb Bedrane, El-Hachemi Amara, Belén Sotillo, Vibhav Bharadwaj, Roberta Ramponi, and Shane M. Eaton.
2018. "Ablation of Copper Metal Films by Femtosecond Laser Multipulse Irradiation" *Applied Sciences* 8, no. 10: 1826.
https://doi.org/10.3390/app8101826