Michel Pons

Study of on-chip integrated antennas using standard silicon technology for short distance communications

A study of on-chip integrated antennas has been carried out in order to test the feasibility of antenna implementation on silicon circuits using standard microelectronics technologies. On-chip integration of a 10-20 GHz dipole antennas coupled to VCOs using standard BiCMOS7/spl trade/ (0.25/spl mu/m) STm process has been investigated. The antenna configuration (10 GHz circuit) is a folded dipole: 2.7 /spl times/ 4.48 mm/sup 2/. For a RF power injected from VCO to the antenna of -7dBm, the EIRP is about -15dBm, the maximum gain about -8 dBi. The radiation efficiency can be estimated at 10%. Considering the antenna-VCO circuits working at 20 GHz, much higher values of radiation efficiency (30%) and gain (-5 dBi) were measured. These promising results tend to demonstrate that on-chip integration of antennas with the RF front-end circuits should be possible in the case of miniaturized communicating objects dedicated to short range applications above 10-20 GHz.

Thermal properties of state of the art novolak-diazonaphtoquinone systems: differences between bulk and film properties

As demonstrated by both thermal analysis (DSC) and thermal flow experiments, the latest resists for advanced i-line lithography exhibit improved thermal properties. Emphasis is placed upon experimental details to obtain reliable and meaningful data. In addition to the results of these experiments, the high glass transition temperatures (Tg) measured, equal or superior to the recommended soft-bake conditions, raise new questions concerning the formation and properties of the resist film. The Tg of the film is shown to be different from that of the bulk material and to depend on the bake conditions. The DSC results are confirmed by thermal flow experiments and a good correlation is obtained between the two methods. The consequences induced by the use of high Tg materials on other steps in the lithographic process, namely standing wave reduction and plasma durability, are also discussed.

Compact diversity antenna with polarization agility

This paper presents a planar inverted F antenna with polarization agility. This novel structure can switch between two linear orthogonal polarizations. PIN diodes are used to switch and select the desired antenna polarization. Simulated results of antenna radiation characteristics are presented. This 2.4 GHz antenna can be used in wireless applications using polarization diversity to overcome fading

Role of surface tension in silylation processes

The DESIRER process has been proposed as an attractive solution to lithographic problems, combining the performance of multilayer systems to the simplicity of monolayer processes. Despite the large number of studies devoted to this type of process, the various mechanisms involved during the silylation and dry development steps are not yet totally understood. The first part of the paper deals with the changes in solubility of the resist layer before and after silylation and suggests that the polarity of the resist is modified during the process. Surface tension measurements are then reported in order to quantitatively evaluate the changes in polarity of the silylated resist. Finally it is shown that the work of adhesion between silylated and non-silylated material can easily explain both the stability of the silylated islands during the HMDS process and the motion of these silylated areas during the dry development step.

Improved methodology to compare diversity performance of several multi-antennas systems

This proposed methodology is an interesting tool which allows to compare several multi-antennas systems designed for a given application. This comparison is made possible thanks to the introduction of the referenced diversity gain. This methodology has the advantage to take into account a group of pondered situations which describes a real application. It is now possible for manufacturers to choose the most adapted system by considering antennas properties (efficiency, size, cost), radio link improvement and combining method complexity. Moreover, simulated or measured values can be used for distribution of incoming radio waves and radiation patterns of antennas.

Novel PIFA with polarization and frequency agility

A compact PIFA with polarization and frequency agility was presented. It was shown that using groups of pin diodes the polarization can be switched between two orthogonal linear polarizations. This antenna is devoted to RF front-end of wireless systems using polarization diversity at the reception. Switching between two frequencies can also be achieved. The antenna presented can cover the entire 2.4 GHz ISM band or can be used for WiMax applications at 3.5 GHz.

Melt flow of the silylated areas during the desire process

The DESIRE@ process has been proposed as an attractive solution to lithographic problems, combining the performance of multilayer systems to the simplicity of monolayer processes. Despite the large number of studies devoted to this type of process, the various mechanisms involved during the silylation and dry development steps are not yet totally understood. The effects of substrate heating, occuring during the dry development process, on the viscous strain of the silylated areas have been recently reported (1). The main results are listed hereafter : * The etch rate selectivity between silylated and non-silylated areas decreases from 15 to15 when the film temperature increases from 20 to 100 “C. * RBS measurements confirm the thermally activated diffusion of silylated chains in the novolac matrix. * Silylation induces a net decrease (from 70 to 5°C) of the glass transition temperature of the novolac polymer. Therefore, the so-called polymer fluid state can be reached during etching, and consequently allows the flow of polymer chains one with respect to each other. Thus, it was shown that the top silylated material can spread and coat the sidewalls of the pattern during the dry development step.