Effective etched width

The etching pattern, or effective etched width, is affected by the following ... 

The depletion width can play a role in analyte-induced modulation of the semiconductor PL [4]. As molecules adsorb onto the surface of the semiconductor, the dead-layer thickness can change, resulting in what can be described as a luminescent litmus test When Lewis bases adsorb onto the semiconductor surface, they donate electron density to the solid, which decreases the electric field and thus decreases the dead-layer thickness. The reduction in D causes an enhancement in the PL intensity from the semiconductor. Figures 2a and 2b present typical PL enhancements observed from an etched n-CdSe substrate Relative to a nitrogen reference ambient, adsorption of the Lewis bases ammonia and trimethylamine cause a reversible increase in PL intensity. In contrast, when Lewis acids adsorb onto the surface, they can withdraw additional electron density, causing the electric field to increase and the PL intensity to decrease. Such effects have been observed with gases like sulfur dioxide [5]. 

Square wave patterns with trench depths of 1.0 pm are etched into silicon substrates to determine the planarization rate, P, of two oxide CMP processes. After patterning, 2.0 pm of Si02 is deposited onto the substrates. The wafers are then polished to remove oxide in 0.2 pm increments. The surface amplitude is measured after each polish and the resultant data tabulated in the table below. Plot log(A Aj) vs. oxide removed and determine P for each process and each trench width. Which process is more effective at planarizing ... 

The effect of pH on patterned TEOS oxide wafers was also investigated using the MIT CMP Characterization Mask Set pitch mask [1]. The pitch mask is a 6 x 6 array of various equal width lines and spaces. The lines and spaces have widths ranging from 2 pm to 1000 pm. The 12 mm pitch pattern was first created in photoresist across the entire wafer. The expiosed oxide was plasma etched to a depth of about 7000 A below the surface. This created an array of 36 sub-arrays with equal width lines and spaces so that half the area was lines and the other half spaces. The wafers were pwlished with silica slurry at 3 different pH values. The oxide thickness at the plateau area (starting surface of the oxide) for 10 sub-patterns of line widths 40,60,80,100,125, 150, 180, 200,250, and 500 pm were measured before and after CMP. The measurements were made in each sub-array in increasing order of line/space width. Five dies were measured along the diameter of the wafer. 

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