Wafer Bonding For Silicon On Insulator Technologies

Sio 2 based soi wafers can be produced by several methods.

Wafer bonding for silicon on insulator technologies.

Specific techniques have been developed to achieve very thin layers through bonding and thinning processes. Silicon on insulator soi wafers are manufactured by bonding one si wafer to the other by activating the surface of both wafers and then placing them together so that a strong bond occurs first through the van der waals attraction and then by forming a covalent bond 59 activation of the superclean si surface is the key to accomplish this bonding typically by a remote plasma process. Bonding occurs after insertion into an oxidizing ambient. In soi wafers the insulator is almost invariably a thermal silicon oxide sio 2 layer and the substrate is a silicon wafer.

First developed in order to obtain soi wafers with very thin top silicon layers these techniques are referred to as bond and etch back silicon on insulator processes besoi. Soi wafers for mems are nearly always fabricated by wafer bonding. For all practical purposes the soi film thickness varies in mems applications from 4 to 200 μm. Wafer bonding the insulating layer is formed by directly bonding oxidized silicon with a second substrate.

7 3 shows a sampling of silicon film and buried oxide thicknesses based on a large number of soi wafer specifications for mems applications. A silicon wafer bonding process is described in which only thermally grown oxide is present between wafer pairs. It is proposed the wafers are drawn into intimate contact as a result of the gaseous oxygen between them being consumed by oxidation thus producing a partial vacuum. The proposed bonding mechanism is polymerization of.

Bonding occurs after insertion into an oxidizing ambient. Therefore process techniques are divided in accordance with the chemical structure of the surface in hydrophilic compare to scheme of a hydrophilic silicon surface or hydrophobic compare to scheme of a hydrophobic silicon surface. The majority of the second substrate is subsequently. The surface state of a silicon wafer can be measured by the contact angle a drop of water forms.

The cavity is formed by wet etching the thermally grown sio 2 layer on top of the silicon substrate. Direct bonding is mostly referred to as bonding with silicon. Sonix wafer inspection systems provide nondestructive testing ndt to detect gaps and voids of less than 0 1 micron enabling superior diagnostic imaging for wafer bonding and device level bond rings in silicon on insulator anodic metal to metal and other high end bonded wafer applications. A silicon wafer bonding process is described in which only thermally grown oxide is present between wafer pairs.

Depending on the type of application the. Defects can be precisely mapped as part of the. It is proposed the wafers are drawn into intimate contact as a result of the gaseous oxygen between them being consumed by oxidation thus producing a partial vacuum. Wafer bonded cmuts can be fabricated by fusion bonding a silicon and a silicon on insulator soi wafers fig.

Simox separation by implantation of oxygen uses an oxygen ion beam implantation process followed by high temperature annealing to create a buried sio 2 layer. 30 a thin sacrificial layer for example a sige layer is grown epitaxially on the initial donor wafer.