Microstructures and crystallization of electroless Ni-P deposits

Crystallization Behaviour of Electroless Ni-P UBM with Medium Phosphorous Induced by Single and Step Heat Treatment

“…Since the EN-P film contains $15 at% phosphorous, it is reasonable that the EN-P consists of nanocrystalline Ni and amorphous EN-P, which is consistent with previous studies. 13,16,17) In an earlier stage of heat treatment at 150 C, the dark spots (Ni) became clearer in shape and increased in size with increasing dwelling time (see Fig. 5(b) and (c)).…”

“…Many studies of the crystallization behavior of EN-P films reported that crystallized Ni-P phases are sensitive to the phosphorus content in the EN-P film. 9,[12][13][14][15][16] In the case of a low (<7$9 at%) and medium (9$18 at%) phosphorous content, the Ni-P compound precipitate is dominated by Ni 3 P. 6,16,18) However, at high phosphorous contents (>20 at%), Ni 3 P and Ni x P y compounds, such as Ni 2 P, Ni 5 P 2 and Ni 12 P 5 , form after heat treatment. 12,13,16) And the transformation from the amorphous Ni-P to the crystalline equilibrium two-phase mixture of Ni and Ni 3 P occurred through the crystallization of the intermediate meta-stable mixture of Ni x P y and Ni in accordance with the Ostwald rule.…”

“…9,[12][13][14][15][16] In the case of a low (<7$9 at%) and medium (9$18 at%) phosphorous content, the Ni-P compound precipitate is dominated by Ni 3 P. 6,16,18) However, at high phosphorous contents (>20 at%), Ni 3 P and Ni x P y compounds, such as Ni 2 P, Ni 5 P 2 and Ni 12 P 5 , form after heat treatment. 12,13,16) And the transformation from the amorphous Ni-P to the crystalline equilibrium two-phase mixture of Ni and Ni 3 P occurred through the crystallization of the intermediate meta-stable mixture of Ni x P y and Ni in accordance with the Ostwald rule. 19) Surprisingly, the medium phosphorous (15 at%) in the EN-P UBM processed by a step heat treatment yielded similar results to those observed with a high phosphorous content (>20 at%) reported in literatures.…”

“…6,12,13,16,17) They claimed that a heat treated EN-P film with a medium P consists of crystallized Ni and Ni 3 P. Figure 7 shows a schematic diagram of the crystallization behavior of EN-P with 15 at% phosphorous. Heat treatment enhanced structural relaxation of the as-plated EN-P film.…”

“…Many studies characterized the crystallization behavior of EN-P films with different phosphorous contents under a single heat treatment. [12][13][14][15][16][17][18] However, few studies are available. Moreover, the effects of the post heat profile, e.g.…”