Polymer coatings are applied to chips and passive components to provide stress relief between the device/component and the plastic package and/or to provide mechanical and environmental protection. The semiconductor industry is actively pursuing a one mask, photosensitive dielectric process for stressbuffer and secondary passivation of memory die. A one mask photo-benzocyclobutene (BCB) process is compared to traditional two mask wet etch processes. This new one mask process reveals 1/3 the total wafer processing time and equivalent reliability (traditional MIL 883C testing) for passivated 100 lead static random access memory components (SRAM's).

No abstract

The adhesion of several commercial underfills (Dexter Hysol FP4511, FP4527, and CNB775-34) to BCB (CY-CLOTENE) 4022, 4024) has been studied through die shear testing and subsequent failure analysis. Die shear values range between 69-90 MPa. Failure analysis by optical microscopy, profilometry and XPS spectroscopy indicates mixed mode failure at various interfaces. From the die shear data collected before and after 24 h water boil for Cyclotene 4022 and 4024 (with AP3000 adhesion promoter) and underfillers FP 4511 and 4527 we find the die shear strength decreases an average of 11% for the four comparisons. Adhesion promoters based on vinyltriacetoxysilane or 3-aminopropyltriethoxysilane show equivalent die shear performance. Substrate surface cleaning based on UV ozone treatment reveals oxidation of the BCB surface which by SIMS analysis remains 0 1 m deep after 10 min of treatment.

A positive-tone and aqueous-base-developable benzocyclobutene (BCB)-based dielectric material curable in air is described in this paper. The prepolymer is made from divinylsiloxane bisbenzocyclobutene (DVS-bisBCB) and BCB-acrylic acid. The formulation contains antioxidants that allow the prepolymer to cure in air and a diazonaphthaquinone to make it photosensitive. Patterned films have high resolution, and via openings are scum-free without a descum operation. Whether cured in nitrogen or in air, the prepolymer produces a film with optical, electrical, thermal, and mechanical properties desirable for many microelectronic applications, such as packaging applications and as a planarization or insulation layer in display applications.

Reaction of CH3Li with (COLReCOQHs or reaction of CeHsLi with (CO)sReCOCH3 produce N(CH3)4+[m-(CO)4Re(COCH3)(COC6H5)]-(2). Thermolysis of 2 at 69 °C produces a 98:2 mixture of N(CH3)4+[m-(CO)4Re(C6H5)-(COCH3)]-(4) and N(CH3)4+[m-(CO)4Re(CH3)(COC6H5)]-( 5), which equilibrate under these conditions. Reaction of 2,4, or 5 with P(CH2CH3)3 gives N(CH3)4+[/ac-(CO)3[P(CH2CH3)3Re(COCH3)(COC6H5)]" (7a). The rate of phosphine addition to 5 to give 7a is 28 times faster than the isomerization of 5 to 4. This implies that methyl migration to rhenium occurs 28-29 times faster than phenyl migration to rhenium in the five-coordinate bisacyl intermediate [(CO)3Re(COCH3)-(COC6H5)]-( 6).