Surface treatment of wire bonding metal pads

Influence of Fluoride Ions Contamination in Front Opening Unified Pod (FOUP) Generating Defective Bonding Pad

“…From this, it is regarded that Al 2 O 3 layer abnormally becomes thicker due to presence of fluoride ion. Alberici et al (2003) reports that the normal pad surface has Al 2 O 3 , fluorine used in pad etching process and aluminium from pad combines to form AlF 3 , and reaction with moisture in exposed environment to analysed. Also to split fluoride ion concentration, argon sputtering step (CF 4 + Ar) other than common CF 4 etching process (CF 4 ) and nitrogen purge step (CF 4 + Ar + N 2 ) into FOUP were introduced.…”

An unusual mechanical failure mode in gold ballbonds at 50μm pitch due to degradation at the Au–Au4Al interface during ageing in air at 175°C

“…1) within the first 5-7 nm of the surface, which is the region within which the natural Al 2 O 3 is found. Excessive F can promote the formation of AlF 3 that in the presence of moisture leads to Al(OH) 3 crystallites, which depletes the bondpad aluminium and promotes growth of thicker Al 2 O 3 on the bond pad surface [20][21][22]. However, the depth at which F is observed in Fig.…”

“…However, some studies have reported extreme loss of mechanical strength (pull and shear) that is attributed to reduction of contact area by the formation of voids [11][12][13] and bondpad contamination [14] while others report good results even after extended isothermal ageing at 175°C for 1000 h [15,16]. Void formation is usually cited as due to uneven diffusion speeds of the Al and Au atoms, the ÔKirkendallÕ effect, but the Kirkendall effect has not been established as the universal mechanism by which such loss of contact area occurs and other mechanisms, including contamination induced corrosion may explain the degradation of intermetallics [19,20]. Corrosion can occur due to dry etching fluorine residues on the bondpad, which react under moist conditions (>50% RH) to form Al(OH) 3 that subsequently causes increased Al 2 O 3 thickness and poor bondability [20,21].…”

“…Void formation is usually cited as due to uneven diffusion speeds of the Al and Au atoms, the ÔKirkendallÕ effect, but the Kirkendall effect has not been established as the universal mechanism by which such loss of contact area occurs and other mechanisms, including contamination induced corrosion may explain the degradation of intermetallics [19,20]. Corrosion can occur due to dry etching fluorine residues on the bondpad, which react under moist conditions (>50% RH) to form Al(OH) 3 that subsequently causes increased Al 2 O 3 thickness and poor bondability [20,21]. Widely different results have been found for bake tests that may depend on bonding parameters, device pad metal, dimensions and loop height and length, factors which can be difficult to quantify when comparing results.…”

A Study on Failures by Abnormal AlxOyLayer after PCT

“…소자의 각 층의 불균일한 화학적 구조로 인해 발생하는 변색(discolor) [5] , 물리적 압력 등에 의해 발생하는 층간박리(delamination) [6] , 특 정 층의 화학적 반응에 의해 발생하는 부식 (corrosion) [7] , 그리고 물리․화학적 영향에 의해 발생하 는 파손(crack) [8] 등이 존재한다. 이들 실패양상의 원인 에 대한 분석 및 해결 방안들이 지속적으로 연구되고 있다 [1,3,8] .…”