Study Of Damage In Crystal Silicon Induced By Nitrogen And Hydrogen Ion Implantation

High fluence gas ions implantuion into crystalline Si can create various defects,such as bubbles, platelets, voids and amorphous zone. Subsequent annealing couldlead to occurrence of surface blisters and exfoliation. Such damage has wide potentialapplications in modern semiconductor device fabrication. Presently, the study of gasion implantation induced damage together with its potential applications has beenreceived more and more attention. In this dissertation, crystalline n-type Cz Si （100）wafers were singly implanted with nitrogen ions and hydrogen gas ions, orsequentially implanted with nitrogen and hydrogen gas ions. The formation andthermal evolution of the surface damage as well as microstructure defects have beenstudied in detail by using various techniques. Moreover, the possible mechanisms forcreation of defects under N and H ion implantation have been discussed. The researchcontents and corresponding results are given as follows:（1） N-type Cz Si （100） wafers were singly implanted or co-implanted with190keV N ions at fluences of510¹⁵cm^-2and110¹⁶cm^-2and80keV H₂ions at afluence of310¹⁶cm^-2, and were then subjected to furnace annealing in N2atmosphere in the temperature range from300℃to600℃for1hour. Techniques ofoptical microscopy （OM）, atomic force microscopy （AFM）, cross-sectionaltransmission electron microscopy （XTEM）, Raman scattering spectrum （RSS） andpositron annihilation spectroscopy （PAS） were employed to characterize surfacemorphology as well as the micro-defects. Our results clearly show that blisters andcraters occur on surface of H singly implanted sample and N and H co-implantedsamples after annealing. Slight increase in surface damage was found for the highfluence of N ion co-implanted sample as comparing with those in H singly implantedor the low fluence N and H implanted samples. The depth of exfoliated craters waswell consistent with the projected range of H ions. Results from XTEM, PAS andRSS show that a lot of H-platelets are formed in the region corresponding to that ofdamaged layer. Thermal annealing could induce evolution of the H-platelets intomicrocracks, which contribute the final surface blistering or exfoliation.（2） Creation of two damaged layers in N ion implanted Si has been welldemonstrated. The first damage layer distributes around the range of N ions, which mainly consist of vacancy clusters. However, the second damage layer is formed atdepth larger than the twice range of N ions, which is mainly composed of {311}rod-like defects. Subsequent H ion implantation together with annealing gives rise totwo modifications in the N implant-induced damage. One is the creation of H-plateletsin the first damage layer, which is responsible for the formation of various surfacedamage phenomena. The other is restoration of structural order in the region betweenthe two damaged bands. The formation and evolution of two damaged bands under Nimplanted or N and H co-implanted Si have been discussed in view of creation andevolution of ion-implant-induced defects and stress.