Fracture Property Improvements of a Nanoporous Thin Film Via Post Deposition Bond Modifications
- PDF / 1,098,681 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 98 Downloads / 188 Views
B3.8.1
Fracture Property Improvements of a Nanoporous Thin Film Via Post Deposition Bond Modifications Jeannette M. Jacques, Ting Y. Tsui, Andrew J. McKerrow, and Robert Kraft Silicon Technology Development, Texas Instruments Inc., Dallas, Texas 75243 ABSTRACT For 90 nm node devices, the group of materials known as organosilicate glass (OSG) has emerged as the predominant choice for intermetal dielectrics. A potential failure mechanism for this class of low-k dielectric films during the manufacturing process is catastrophic fracture due to channel cracking. The use of an electron beam curing process is being investigated for improvement in the mechanical strength of these silicon-based materials. Within this work, the effects of curing dose (micro-C/cm2) upon the mechanical properties of OSG thin films were characterized. For a set process voltage and current, linear relationships exist between the dose and several mechanical film properties. Channel crack growth velocities were also measured for these cured materials. As the cure dose is increased, the crack growth rate decreases according to a power law relationship. The structural film changes induced by the electron beam cure process are addressed, focusing on their impact upon the mechanical strength of OSG thin films. INTRODUCTION For 90 nm node devices and beyond, the integration of low-k dielectric films is required to maintain and improve device performance. The class of materials known as organosilicate glass (OSG) has emerged as the primary candidate for intermetal dielectrics. During the manufacturing process, a potential failure mechanism for OSG films is catastrophic fracture due to channel cracking. The driving force for channel cracking is dependent upon several material properties, with the residual film stress, density, and plane strain modulus serving as key factors. 1-2 The drive to improve the mechanical strength of these silicon-based materials, while maintaining their low dielectric constant, has proved challenging. The use of an electron beam (EB) curing process has been examined to overcome the aforementioned difficulties. Recently published works have emphasized the use of simultaneous EB curing for hybrid structures. 3, 4 Superior electrical performance and structural reliability were measured for samples processed according to this simultaneous cure method. 3 The mechanical strengths of full dielectric stacks have been observed to improve, as well as the adhesion strengths between component films. 4 To date, the benefits of EB curing for plasma enhanced chemical vapor deposition (PECVD) dielectric layers are widely unknown. In these studies, the effects of EB curing on the properties of individual OSG films are characterized for a set curing temperature, voltage, and current. EXPERIMENTAL CONDITIONS PECVD techniques were employed to deposit k ~ 2.6 OSG films directly onto 200 mm silicon wafers. A large area, cold cathode, electron beam source was used to cure these films at a temperature of 400oC and pressure of 0.01 mT. Samples were pro
Data Loading...
