Laser-annealing processes

In JP-A-3108371 cross-talk is reduced by introducing metal atoms by a laser annealing process at regions between photodiodes. 

Laser annealing processes are much less well characterized than the thermal annealing processes discussed above. SIMS depth profiles have been used to study these processes (44). The use of excimer lasers for semiconductor processing was recently reported. SIMS depth profiles of B In SI after XeCl laser annealing showed a nearly flat B distribution to a Junction depth of about 0.9 pm with an Initial Implant peak of about 0.3 pm... 

Boron implant with laser anneal. Boron atoms are accelerated into the backside of the CCD, replacing about 1 of 10,000 silicon atoms with a boron atom. The boron atoms create a net negative charge that push photoelectrons to the front surface. However, the boron implant creates defects in the lattice structure, so a laser is used to melt a thin layer (100 nm) of the silicon. As the silicon resolidihes, the crystal structure returns with some boron atoms in place of silicon atoms. This works well, except for blue/UV photons whose penetration depth is shorter than the depth of the boron implant. Variations in implant depth cause spatial QE variations, which can be seen in narrow bandpass, blue/UV, flat fields. This process is used by E2V, MIT/LL and Samoff. 

MBE growth of very thin layer of boron and silicon. The problems associated with boron implant and laser anneal can be overcome by growing a very thin (5 nm) layer of silicon with boron atoms on the backside of the thinned CCD (1% boron, 99% silicon). The growth is applied by molecular beam epitaxy (MBE) machines. This process was developed by JPL and MIT/LL. 

A wide variety of process-induced defects in Si are passivated by reaction with atomic hydrogen. Examples of process steps in which electrically active defects may be introduced include reactive ion etching (RIE), sputter etching, laser annealing, ion implantation, thermal quenching and any form of irradiation with photons or particles wih energies above the threshold value for atomic displacement. In this section we will discuss the interaction of atomic hydrogen with the various defects introduced by these procedures. 

G.E. Jellison, Jr., Optical and Electrical Properties of Pulsed Laser-Annealed Silicon R.F. Wood and G.E. Jellison, Jr., Melting Model of Pulsed Laser Processing R.F. Wood and F.W. Young, Jr., Nonequilibrium Solidification Following Pulsed Laser Melting... 

D.M. Zehner, Surface Studies of Pulsed Laser Irradiated Semiconductors D.H. Lowndes, Pulsed Beam Processing of Gallium Arsenide R.B. James, Pulsed C02 Laser Annealing of Semiconductors R. T. Young and R.F. Wood, Applications of Pulsed Laser Processing... 

To produce fullerenes and metallofullerenes, a temperature above 800 °C was found to be necessary, and below this critical temperature no fullerenes were produced (Haufler et al., 1991 Suzuki et al., 1997a Wakabayashi et al., 1997), suggesting that relatively slow thermal annealing processes are required to form fullerenes and metallofullerenes. The laser-furnace method is suited to the study of growth mechanism of fullerenes and metallofullerenes (Curl and Smalley, 1991 Haufler et al., 1991 ... 

Indispensable and continue to be Important In the development of models for range statistics In Ion Implantation. SIMS depth profiles are also used to monitor and develop an understanding of the diffusion of dopants during laser and thermal annealing processes. Metallization and thin films have also been Investigated by SIMS. In addition SIMS depth profiles are useful for failure analysis and problem solving. 

In addition to the three basic microfabrication steps discussed above, other fabrication techniques are quite useful. We will briefly discuss a few of them, namely lift-off, annealing, liquid phase photopolymerization, micromolding, soft lithography, electroplating, sacrificial processes, bonding, surface modification, laser-assisted processes, planarization, and fabrication on flexible substrates and curved surfaces. Some of these techniques do not necessarily belong to the traditional repertoire of microfabrication of ICs. However, they have proved very useful for the creation of other types of microdevices and systems such as MEMS, microfluidics, and labs on chips. 

Discusses many microfabrication techniques, including deposition, photolithography, etching, annealing, liquid-phase photopolymerization, micromolding, electroplating, laser-assisted processes, and more... 

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