Anders Söderbärg

Spontaneous bonding of hydrophobic silicon surfaces

The initial attraction of silicon surfaces etched in aqueous and buffered HF solutions have been studied, by observing the spontaneity and velocity of the contact wave. Also, the effect of a following water rinse was investigated. The bond strengths were determined by measuring the surface energy of the bonds at room temperature. Surfaces etched in an aqueous HF solution, with no subsequent water rinse before drying and contacting, bond spontaneously. If water rinsing is performed after the etch, the spontaneity is lost and the surfaces bond only if a pressure is applied. Surfaces etched in a buffered HF solution did not bond.

A self-aligned lateral bipolar transistor realized on SIMOX-material

Lateral bipolar transistors, compatible with a CMOS process on SOI, have been fabricated on high quality SIMOX material. A self-aligned nitride spacer technique is used for base width definition and for emitter alignment. Current gains of 40 and high collector-emitter breakdown voltages have been obtained for transistors with base widths of 4000 AA. >

Modification of silicon surfaces with H2SO4:H2O2:HF and HNO3:HF for wafer bonding applications

Two combinations of oxidizing and etching agents, H2SO4:H2O2:HF and HNO3:HF, have been used to modify silicon surfaces prior to wafer bonding. The chemical oxide thickness can be adjusted between 0 and 10 Angstrom by tuning the HF content of the mixtures

A novel high-frequency high-voltage LDMOS transistor using an extended gate RESURF technology

A novel high-voltage DMOS transistor with a low doped extended gate is presented. The device withstands 240 V in the off-state and has a specific on-resistance of 24 m/spl Omega/cm/sup 2/. The transconductance is 60 mS/mm at 3 V gate voltage. The sub-micron channel length gives small-signal high-frequency performance as f/sub T/=2.8 GHz and f/sub max/=5.8 GHz and the unilateral power gain at 900 MHz is over 15 dB. The dependence of breakdown voltage and on-resistance on gate doping level and polysilicon gate length is investigated with device simulations. It is found that the breakdown voltage is highly dependent on the gate doping level.

Improved direct bonding of Si and SiO2 surfaces by cleaning in H2SO4:H2O2:HF

A method for silicon surface preparation prior to wafer bonding in presented. By cleaning thp wafers in a H2SO4:H2O2 mixture in which a small amount of HF is added, and then rinsing in H2O, the bon ...

A suggested mechanism for silicon direct bonding from studying hydrophilic and hydrophobic surfaces

Silicon direct bonding (SDB) between both hydrophilic and hydrophobic surfaces was studied by measuring the surface energies. Without annealing, roughly the same energies were measured for both types of surfaces. The strongest bonds were achieved for hydrophobic surfaces, annealed at 600 degrees C and above. The established mechanism for SDB, where OH groups are held responsible for the initial attraction force, cannot explain bonding between hydrophobic surfaces where almost no OH groups are present. By calculating the surface energy/mole, and comparing this to data for hydrogen bonds and van der Waals forces, a novel mechanism for SDB is proposed where the initial attraction is due to van der Waals forces.

The Effects of HF Cleaning Prior to Silicon Wafer Bonding

The effects of preparation of silicon surfaces in hydrofluoric acid (HF) solutions, prior to direct wafer bonding, is investigated. Surface analysis with atomic force microscopy, electron spectroscopy for chemical analysis, and estimation of the surface particle density is made. This is related to results from room temperature bonding experiments. A diluted (1-10%) HF solution is most favorable for hydrophobic silicon wafer bonding. The subsequent water rinse should be omitted, or performed in a careful way, to avoid particle contamination. HF:NH 4 F solutions generally are not favorable for bonding. The initial room temperature bonding is attributed to the relatively weak van der Waals forces, which makes the bonding sensitive to the surface roughness and particle density. The surface chemistry appears to have a second order influence in hydrophobic bonding

Transient Measurements of Heat Distribution in Devices Fabricated on Silicon-On-Diamond Material.

Thermal properties of devices fabricated on different silicon-on-diamond (SOD) and silicon-on-insulator (SOI) structures have been investigated. A new method for transient measurements of temperatu ...

Continuous ink-jet print head utilizing silicon micromachined nozzles

Abstract The nozzle design for a colour ink-jet print head using Hertzs continuous ink-jet method is described. A multiple jet implementation with eight jets per colour is developed by using silicon nozzle array plates manufactured by micromachining. Three different arrays have been tested in terms of directionality and clogging. In the final design, the orifices are formed as conical piles, in order to lengthen the effective channel and to reduce the surface wetting.

Investigation of Buried Etch Stop Layer in Silicon Made by Nitrogen Implantation

A novel way to fabricate a buried etch stop layer in silicon is presented in this article. The etch stop layer is formed by nitrogen implantation and the investigations show that a dose of 1.10 17 14 N + -ions/cm 2 at 140 keV is enough to effectively stop the silicon etch reaction in an ethylenediamine-pyrocatechol-water solution. The nitrogen concentration where the etch reaction stops was estimated with secondary ion mass spectroscopy measurement to be about 2.5.10 21 ions/cm 2 , which is far below the necessary concentration for nitride formation