Shallow boron junctions and preamorphization for deep submicron silicon technology

Abstract

In this study, shallow p+-n junction diodes were formed by implanting BF+2 ions into single-crystal silicon or silicon preamorphized by either Si or Ge implantation. BF+2 implantation at energies of 20 or 25 keV and a dose of 1×1015 cm−2 was followed by furnace annealing at 600 °C in nitrogen ambient. Most samples received a further nitrogen-ambient anneal at 850 °C, with various periods of time. Secondary ion mass spectroscopy was used to measure the B profiles. Cross-sectional transmission electron microscopy was used to study the amorphous layers and the defects remaining after annealing. Electrical characterization of the diodes is described. In preamorphized samples, the residual defect density decreases, and the defect band located at the original amorphous-crystalline interface becomes sharper, as the mass of the amorphizing ion species is increased. Ideal low-leakage shallow junctions can be made following either Si or Ge preamorphization and furnace annealing, without removing all the defects induced by preamorphization. This is achieved by containing the implanted B profile completely within the amorphous layer, and by containing the defect band completely within the final biased junction. However, even without a preamorphization step, ideal low-leakage shallow junctions were obtained after BF+2 implantation and 600 °C furnace annealing. This suggests that preamorphization may not ultimately be needed for practical engineering of shallow junctions.

Shallow source/drain extension formation using antimony and indium pre-amorphization schemes for 0.18- to 0.13-μm CMOS technologies

“…it is known that diode leakage is sensitive to a pre-amorphization condition when the primary-dopant implant condition is fixed [4,5,9]. However, different Sb implant conditions on device drive current and SCE need to be further evaluated.…”

“…The high diode leakage is mainly caused by the residual implant damage generated by the pre-amorphization implant after the high temperature annealing. To prevent the implant damage from reaching the depletion region of a junction is essential for assuring low diode leakage [4,5,9]. Because L_ is insensitive to Sb pre-amorphization conditions, we believed that Sb cannot The effects on device performance for 1st spacer in different thickness, mainly Lirive and L_, were also studied.…”

“…First, the channeling tail of an as-implanted pnmary-dopant (BF2 in this case) profile can be reduced if the implanted substrate has been pre-amorphized prior to the primary-dopant implantation [7,14]. Second, the re-growth of the pre-amorphized region and the formation of the end-of-range defects during the post-implant annealing can reduce excess Si interstitials generated by the implantation process, which can retard transient enhanced diffusion (TED) of the primary dopants [4][5][6][7][8][9]. Different Sb implant conditions were used to study their effects on boron diffusion profiles.…”

“…One of the methods to form shallow junction is to use the pre-amorphization scheme [1][2][3][4][5][6][7][8][9]. Si and Ge have been widely used to pre-amorphize a Si substrate before primary dopant implantation [3,[5][6][7][8][9]].…”

Recoil implantation method for ultrashallow p+/n junction formation

“…The annealed B profiles have humps that do not appear in the as-recoiled B profiles. The B hump centered in the end-of-range ͑EOR͒ region was observed by many authors, 4,[16][17][18][19][20][21][22] though the microstructure and kinetics of it still remains controversial. [21][22][23][24][25][26] The amorphous/crystalline ͑a/c͒ interfaces predicted by the TA-MIX simulations are also shown in Fig.…”