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The UV-induced damages to the gate oxide in a commercially available high-density-plasma dielectric oxide deposition system for the ultra-large integrated circuit fabrication process were analyzed systematically using the metal-oxide-semiconductor capacitors with different antenna ratio. UV-induced damages exclusively in the gate oxide were evaluated by depositing 2500 A thick oxide layer only once and twice on the two wafers separately and comparing the two results: the deposition of the oxide layer of only 2500 A did not cause any degradation in the SPDM wafer while the double deposition revealed antenna-ratio dependent shift of the breakdown voltage. The deviation of the values of breakdown voltage of the damaged wafer from its normal ones was found mainly at the center of the wafer where the intensity of the UV light is generally higher in the inductively coupled plasma source.

In this study, etching characteristics of oval-shaped contact were investigated. The oval-shaped contact showed different etching characteristics compared to the circular contact. The long axis cross-section of oval-shaped contact showed a more vertical profile and a less bowing compared to the short axis. To explain these phenomena, we simulated ion reflection from sloped oval-shaped hard-mask. From the simulation, we found that the ions reflected from hard-mask accumulated more toward short axis sidewall first. This ion accumulation and asymmetric charging explained the reason behind larger bowing and slopped profile phenomena of short axis.

Plasma process-induced “white pixel defect” (WPD) of CMOS active pixel sensor (APS) is studied for Si3N4 spacer etch back process by using a magnetically enhanced reactive ion etching (MERIE) system. WPD preferably takes place at the wafer edge region when the magnetized plasma is applied to Si3N4 etch. Plasma charging analysis reveals that the plasma charge-up characteristic is well matching the edge-intensive WPD generation, rather than the UV radiation. Plasma charging on APS transfer gate might lead to a gate leakage, which could play a role in generation of signal noise or WPD. In this article the WPD generation mechanism will be discussed from plasma charging point of view.

This paper reports on the process dependence of contact resistance of silicide/n+ Si and silicide/p+ Si contact. Three processes such as contact etching, Si treatment and pre-treatment are investigated with contact resistance point of view. Only silicide/p+ Si contact resistance has been changed as etching time of contact increases while silicide/n+ Si contact resistance has been regularly maintained. We have modeled that fluorine used in contact etching can scavenge or deactivate boron in p+ Si, resulting in degradation of silicide/p+ Si contact resistance. In order to confirm the model, two different gases (hydro carbon fluoride/carbon fluoride) during Si treatment right after contact etching were applied. As a result, the silicide/p+ Si contact resistance was increased in carbon fluoride case, which has higher fluorine ratio to carbon than hydro carbon fluoride case. It is also observed that the silicide/p+ Si contact resistance was increased proportionally with time of fluorine-based pre-treatment before silicide formation.

Characteristics of the plasma and the poly-Si etching in a pulse modulated helicon wave plasma were studied. The self bias voltage induced on the wafer by r.f. bias of 300 kHz was directly measured with a Pt wafer by high voltage probe. Even though the r.f. bias frequency of 300 kHz was less than the ion plasma frequency, it was observed that the self bias voltage was induced, which contradicts the conventional thoughts. In the off period of the source power in the pulse mode, the weak plasma was sustained only by the r.f. bias power. This weak plasma in the pulse mode induced higher self bias voltage compared with the continuous mode because the self bias voltage decreased as the plasma density increased. The pulse modulated helicon wave plasma with low frequency r.f. bias effectively eliminated the local side etching but enhanced the resist erosion due to higher self bias voltage. The Si etch rate and the selectivity of Si to photo-resist were enhanced by adjusting the duty ratio.

We have studied the characteristics of photoresist (PR) ashing using N 2 /O 2 plasmas in ferrite-core inductively coupled plasma etcher. By varying the O 2 /(O 2 + N 2 ) gas flow ratio, we have changed the PR ash rate and the low-k material etch rate, obtaining the PR ash rate and the PR to low-k materials etch selectivity, respectively, of 15,000 A/min and 180. Fourier transform infrared spectroscopy and HF etch test coincidentally indicated that the ash damage to the low-k material decreased with decreasing the O 2 /(O 2 + N 2 ) gas flow ratio.

Aluminium oxide films were deposited on silicon substrates at low temperatures (150–300 °C) by plasma-enhanced chemical vapour deposition using trimethylaluminium, N 2 O and helium gases. The film properties including chemical composition, depth profile, microstructure, refractive index and step coverage were investigated, and the dependence of the film properties and deposition rate on the deposition temperature were also studied. The deposition rates of aluminium oxide films deposited at 150 and 170 °C are very high, reaching 320–400 A min −1 . On the contrary, above 200 °C the deposition rates are constant at 160 A min −1 . The film deposited at 150 °C has an amorphous structure and those above 250 °C have an extremely fine γ-alumina crystalline structure. Hydrogen is the only impurity detected in the aluminium oxide film and its concentration increases as the deposition temperature decreases. The film deposited at 250 °C exhibits a very smooth surface and fairly conformal step coverage. The temperature dependence of the deposition rate and hydrogen content is explained by the change in adsorption type and desorption rate of reactants with temperature.