Photosensitive benzocyclobutene for stress-buffer and passivation applications (one mask manufacturing process)

Abstract

Photosensitive Benzocyclobutene (Photo-BCB) has been widely reported on for use as a dielectric material in multilayer packaging applications, including: MCMs, IO redistribution, and flat panel display. Photo-BCB has many properties which are highly attractive for these applications, including: a simple processing scheme which is compatible with existing IC manufacturing techniques, low level of ionics, low moisture uptake, low cure temperatures, rapid thermal curing, high optical transparency, high planarization level, high thermal stability, high solvent resistance, very low outgassing, and a low dielectric constant.Photo-BCB is also being actively evaluated for wafer-level applications such as stress-buffer and passivation. In this paper, we will discuss the Photo-BCB properties and processing steps as they relate to these two applications. We will also compare the manufacturing scheme based on a one mask process for memory die, to the steps in a two mask process for stress-buffer and passivation.

Variable Frequency Microwave and Convection Furnace Curing of Polybenzoxazole Buffer Layer for GaAs HBT Technology

“…Additionally, PBO material is known for its excellent thermal stability and thermo-oxidative resistance, and can be used in and is compatible with various front-end and back-end assembly applications [11], [21]- [25], [27]. The material is also easily processed and with a photosensitizer will act as a photoresist or hardmask during etching, as has been shown with other photosensitive polymer materials [4], [9], [28], [29]. Furthermore, the developer that is usually utilized with this photosensitive PBO is tetramethyl ammonium hydroxide (TMAH) in water, an environmentally benign aqueous solution.…”

“…In semiconductor processing, the buffer layer should have good physical, mechanical, chemical, electrical, and thermal characteristics, and should be compatible with subsequent processing, including back-side wafer process steps, such as wafer thinning and scribe and break, and assembly process steps, such as die-pick and attach, wirebonding, and mold compound application [1], [4], [13], [26], [28], [38]. In all of these cases, the material used for the buffer layer also has to be stable and be compatible with the materials used in the above processes, including wafer crystal bond material, mold compound, epoxy, and the chemicals used in these processing steps, such as acetone.…”

Filling of very deep, wide trenches by BenzoCycloButene polymer

“…Unless otherwise mentioned, data included in Table 1 are collected from the manufacturer's data sheet (Dow Chemical Company 2005). BCB which has been primarily used as interlayer dielectric (ILD) for microelectronics applications (Mills et al 1997), finds today a success in MEMS applications more particularly for packaging (Jourdain et al 2005;Seok et al 2006) and thermal isolation purposes (Ma and Wagner 1999;Strandjord et al 1997). …”

Residual thermomechanical stresses in thinned-chip assemblies

“…Accordingly its Young modulus at 40 C is 2.6 GPa and 0.1 GPa at 230 C (the Young modulus is assumed to vary linearly in-between). A summary of the properties of pre-cured BCB is given in Table II [16]. Fig.…”