Understanding the microwave annealing of silicon

Abstract

Though microwave annealing appears to be very appealing due to its unique features, lacking an in-depth understanding and accurate model hinder its application in semiconductor processing. In this paper, the physics-based model and accurate calculation for the microwave annealing of silicon are presented. Both thermal effects, including ohmic conduction loss and dielectric polarization loss, and non-thermal effects are thoroughly analyzed. We designed unique experiments to verify the mechanism and extract relevant parameters. We also explicitly illustrate the dynamic interaction processes of the microwave annealing of silicon. This work provides an in-depth understanding that can expedite the application of microwave annealing in semiconductor processing and open the door to implementing microwave annealing for future research and applications.

Tuning of Schottky Barrier Height at NiSi/Si Contact by Combining Dual Implantation of Boron and Aluminum and Microwave Annealing

“…Moreover, the peak annealing temperature during the MWA process was determined to be below 344 °C, which is far below the lowest record of 400 °C using conventional thermal annealing methods [ 30 ], even when accounting for measurement errors produced by the infrared pyrometer [ 11 ]. Previous studies have demonstrated that the lower annealing temperature of the MWA process results from its unique non-thermal effect, which reduces the bonding activation energy during the recombination process [ 23 , 31 ]. Thus, a non-thermal effect could play a crucial role in reducing the temperature during nickel silicide formation.…”

“…The mean projected range can also be determined from the location of the first crest of Al in Figure 4 , which appeared at the same position as the as-implanted Al peak. Given the deeper amorphous region produced by the higher implantation energy of Al, where strong rotation of dipoles occurs in response to the alternating electromagnetic field, the dielectric polarization loss effect was greatly induced [ 23 ], thereby enhancing absorption of microwaves during the MWA process. Combined with the intensified non-thermal effect reducing the dopant activation energy, the dopants were activated to a large extent.…”

“…This shallower amorphous layer was rapidly consumed during the formation of nickel silicide. It has been reported that both the dielectric polarization loss effect and non-thermal effect vanish in silicon after the defects are fully repaired [ 23 ]. Therefore, sufficient microwave absorption could not be induced in N2 to enable the activation of the dual dopants, resulting in an insignificant non-thermal effect.…”

“…The microwave annealing (MWA) process has gradually been accepted as an alternative annealing method because of its various beneficial properties, such as selective annealing [ 21 ], reduced diffusion [ 22 ], and higher activation of the dopant at a relatively lower temperature [ 23 ] compared with conventional thermal annealing methods, such as furnace annealing and rapid thermal annealing (RTA). The capacity toward effective SBH regulation in a DS NiSi/Si contact was improved when using 600-s MWA instead of 600-s RTA at a lower temperature [ 11 ].…”

“…However, to improve the competitiveness of MWA for SBH tuning, the duration of MWA should be reduced to achieve further reduction of the thermal budget. Previous works have shown that microwave absorption can be enhanced in silicon by using heavier ions (B/As) or Ge/Si pre-amorphization implantation [ 24 ], which would lead to further defect generation [ 23 ]. Therefore, a feasible strategy to enhance the absorption of microwaves is to increase the defect density by implanting an additional dopant, for which Al is an ideal candidate.…”