In manufacturing a semiconductor device, static electricity is generated while contact holes are formed in an interlayer insulating film by dry etching. Damage to a pixel region or a driving circuit region due to travel of the static electricity generated is prevented. Gate signal lines are spaced apart from each other above a crystalline semiconductor film. Therefore a first protective circuit is not electrically connected when contact holes are opened in an interlayer insulating film. The static electricity generated during dry etching for opening the contact holes moves from the gate signal line, damages a gate insulating film, passes the crystalline semiconductor film, and again damages the gate insulating film before it reaches the gate signal line. As the static electricity generated during the dry etching damages the first protective circuit, the energy of the static electricity is reduced until it loses the capacity of damaging a driving circuit TFT. The driving circuit TFT is thus prevented from suffering electrostatic discharge damage.

Semiconductor Device and Method of Manufacturing the Same

The gettering efficiency of silicon implanted with carbon at a dose of 1 × 1016 cm−2 and energies in the range of 0.33–10 MeV was tested by carrier lifetime measurements. After an intentional contamination of the sample back side with gold as a lifetime killer, on the front side we found values for the generation lifetime of the minority carriers in the range of 27–78 μs and 144–569 μs for the 2.4 MeV and 10 MeV implantation, respectively. These values are higher by 1–2 orders of magnitude as compared to unimplanted silicon. Furthermore, an anomalous doping effect of carbon was found which depends on the annealing method (furnace, RTA). The microstructure of the carbon-implanted layer was investigated by electron microscopy of cross-sectional samples showing dislocation loops which surround the stacking faults. These defects are located within a band of very small precipitates.

Proximity getterihg by MeV-implantation of carbon: microstructure and carrier lifetime measurements

Silicon-on-insulator (SOI) structures can be obtained by the combined implantation of oxygen and nitrogen into silicon A thorough transmission electron microscope study of the sequential N and O implantation in Si is reported It is shown that the resulting microstructure strongly depends on the implantation sequence and dose In general the buried layer remains amorphous Only in one case did the lower part of the buried layer crystallize in the α-Si3N4 phase When nitrogen is implanted prior to oxygen, α-Si3N4 precipitates are formed below the buried layer They contain a considerable portion of the implanted nitrogen A particular orientation relationship was found to exist between the α-Si3N4 precipitate and the Si matrix; it was determined as (001)αSi3N4//{111}Si

TEM study of combined oxygen and nitrogen implanted silicon

The gettering efficiency of silicon implanted with carbon ions in the energy range 0.33–10 MeV was tested by carrier lifetime measurements. After an intentional contamination of the sample back side with gold as a lifetime killer, we found values for the generation lifetime of the minority carriers on the front side higher by 1–2 orders of magnitude as compared with unimplanted silicon.

Carrier lifetime increase in silicon by gettering with a MeV-implanted carbon-rich layer

The aim of this work was to study the formation of silicon-on-insulator (SOI) structures produced by the double implantation of low dose (10 16 –10 17 cm −2 ) oxygen and nitrogen ions into silicon. Secondary ion mass spectrometry (SIMS) analyses were carried out on the materials, both in the as-implanted state and after annealing at a range of temperatures and times. Selected samples were also studied using cross-sectional transmission electron microscopy (XTEM) and Rutherford backscattering (RBS). In the as-implanted state, varying the sequence and the dose of the double implants produced very different and interesting behaviour. When oxygen was implanted before nitrogen, both the oxygen and nitrogen profiles were seen to shift deeper into the SOI structure than expected. However, when nitrogen was implanted first, a shift was not observed. On annealing these materials, the optimum annealing conditions were found to be 1200 °C for 2 h. This produced very good quality materials with buried layers that had sharply defined interfaces. XTEM studies showed the buried layer to be continuous with the thickness and depth of the layer agreeing with the corresponding SIMS profile.

Study of silicon-on-insulator structures formed by low dose oxygen and nitrogen implantation

Using Rutherford backscattering spectrometry the redistribution and gettering of implanted gold was investigated in silicon-on-insulator structures produced by high-dose nitrogen implantation. The gettering efficiency of a structure annealed at 1000 degrees C containing a highly damaged silicon region near to the buried compound layer is more pronounced than that of a 1200 degrees C-annealed structure with a lightly damaged silicon top layer. Gettering takes place at the interregion between silicon and silicon nitride.

R. Groetzschel

Papers

Heavy metal gettering in buried nitride silicon-on-insulator structures