Sn-Ag Solder Bump Formation for Flip-Chip Bonding by Electroplating

Arai, Shigeo; Akatsuka, Hideki; Kaneko, Norio

doi:10.1149/1.1606687

Cited by 42 publications

(19 citation statements)

References 15 publications

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“…Many authors studied the electrochemical behaviour of pure tin [3][4][5][6][7][8][9] and pure silver [10][11][12] in different media. But few studies are done on tin-silver alloys [13][14][15][16][17][18][19][20][21][22]. The behaviour of some alloys in fluoride solutions was studied by some authors [23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Behavior of Sn-Ag Alloys in Sodium Fluoride Solutions

Ameer¹,

Ghoneim

Fekry

et al. 2006

Mat.-wiss. u. Werkstofftech.

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Passivation and corrosion behavior on Ag, Sn and Sn-Ag alloys were studied using various electrochemical techniques, i.e. opencircuit, potentiodynamic polarization and impedance measurements. The specimens were polarized between -1000 and 500 mV vs. saturated calomel electrode (SCE) in naturally oxygenated NaF solution of different concentrations. The results of potentiodynamic polarization showed that each of i corr and i c increases with increasing either Sn% or F -concentration. EIS measurements under open circuit conditions confirmed well this behavior. The effect of temperature was also studied in 0.5M NaF at temperature range of 291K to 333K. The corrosion current i corr was observed to increase with temperature for the same electrode. The activation energy was calculated according to Arrhenius equation and its value was found to decrease considerably with increasing the Sn content in the alloy.

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Section: Introductionmentioning

confidence: 99%

Electrochemical Behavior of Sn-Ag Alloys in Sodium Fluoride Solutions

Ameer¹,

Ghoneim

Fekry

et al. 2006

Mat.-wiss. u. Werkstofftech.

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“…As a bumping method, electroplating is considered to be a suitable process due to its efficiency in fabricating smaller sized and narrower pitched bumps. 20) Electroplating processes for solder bumps generally employ a photo-resist-mold (PRM) on a Si wafer [20][21][22][23][24][25][26] to confine the cathode surface area and control the shape of the deposits. However, applying a PRM requires a series of processes; PR coating, ultra-violet (UV) exposure, development and PR removal, which involve extra time and cost.…”

Section: Introductionmentioning

confidence: 99%

A New Non-PRM Bumping Process by Electroplating on Si Die for Three Dimensional Packaging

et al. 2010

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A new bumping process on a Si die by electroplating without a photo-resist-mold (PRM) was assessed for the three dimensional (3D) stacking of Si dice. In this process, solder bumps were deposited selectively onto the surface of a Cu plugged-through silicon-via (TSV) in a Si die. Since lithography related processes to make a PRM for solder bumping were omitted, it can reduce the production time and cost for bumping. The substrate was a Si wafer, and TSVs were produced by deep-ion-reactive-etching (DRIE). As an insulation layer, SiO 2 was formed by high-density-plasma-chemical-vapor-deposition (HDPCVD) or wet oxidation method. A Ti adhesion and an Au seed layers were deposited by sputtering. Cu was plugged into the vias by pulsed direct-current (DC) electroplating. The backside of the Si wafer was ground by chemicalmechanical-polishing (CMP). Sn bumps were electroplated on the Cu plugged vias by a current supplied through a Cu-overplated layer (COL) on the vias surface. As experimental results, wet oxidation provided a uniform SiO 2 thickness through the via depth, whereas the SiO 2 thickness by HDPCVD decreased with the via depth. The Ti and Au thicknesses also decreased along the via depth. In electroplating for Cu plugging, defect-free Cu plug was achieved by pulsed DC for 18 h, where one cycle composed of a 5 s cathodic term with À12:2 mAÁcm À2 and a 25 s anodic term with 2.3 mAÁcm À2 . Sn bumping using COL without PRM was accomplished successfully at a current density of À30 mAÁcm À2 for 15 min. The diameter and height of the Sn bumps ranged from 48.5 to 52 mm and 22 to 25 mm, respectively. The bumps had a rivet head shape without a columnar part and showed facets on the bump surface. The COL was removed by CMP without damage to the bumps.

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“…In this line of research, tin has found numerous uses as the active ingredient of the existing solders since it wets and alloys with a wide range of commonly used base metals. Among the binary tin alloys which have been studied as promising candidates are tin-copper [3][4][5][6], tin-aluminum, [7] and tinsilver [8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

The electrochemical behavior of Sn–Ag binary alloys in sulfate solutions

Ameer

Ghoneim

Fekry

2010

Materials & Corrosion

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The corrosion and passivation behavior of four binary xSn-Ag (x ¼ 26, 50, 70, and 96.5 wt%) alloys and their pure metal components was investigated in sodium sulfate solutions using electrochemical techniques. The influence of two different electrolytic parameters, namely, concentration (0.01-1.0 M) and pH (3.0-11.0) were studied while the specimens were potentiodynamically polarized between À1000 and 500 mV versus saturated calomel electrode (SCE). The results showed that the corrosion current density (i corr ) increases with increasing either the tin content in the alloy or the SO 2À 4 ions concentration in the electrolyte. Increasing the pH value of a constant composition sulfate solution was found to improve the corrosion resistance of the tin-richer alloys (x ¼ 50-96.5 wt%), and decreases a little the stability of the silver-rich one (74 wt% Ag). Impedance measurements at the free corrosion potential (E corr ) give good support for these results, where a small addition of tin to silver up to the intermetallic ratio (x ¼ 26 wt%) gives an alloy with better corrosion resistance to the aggressive sulfate medium. In terms of the tin ratio, the order of surface film stability on the tested samples, generally follows the ranking: 26 > 96.5 > 50 > Ag > 70 > Sn. The good corrosion resistance of the tin-rich alloy (x ¼ 96.5 wt%), surpassing those for the pure constituents tin and silver can be attributed to the homogenous phase structure of this eutectic mixture.

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Sn-Ag Solder Bump Formation for Flip-Chip Bonding by Electroplating

Cited by 42 publications

References 15 publications

Electrochemical Behavior of Sn-Ag Alloys in Sodium Fluoride Solutions

Electrochemical Behavior of Sn-Ag Alloys in Sodium Fluoride Solutions

A New Non-PRM Bumping Process by Electroplating on Si Die for Three Dimensional Packaging

The electrochemical behavior of Sn–Ag binary alloys in sulfate solutions

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