Resist stripping

Resist stripping- Both wet and dry removal processes are used at this step in processing. Dry ashing removes the bulk of the photoresist and wet stripping removes remsuning residues. 

Unsecured objects, such as bricks and gas cylinders, near the edges of elevated surfaces, such as catwalks, roof tops, and scaffolding, which may dislodge and fall on workers Debris and weeds that obstruct visibility Install skid-resistant strips and other antiskid devices on slippery surfaces Construct operation pads for mobile facilities and temporary structures Construct loading docks, processing and staging areas, and decontamination pads... 

From an IC manufacturing standpoint, two additional considerations fuel the drive toward dry etch processes. Relatively large volumes of dangerous acids and solvents must be handled and ultimately recycled or disposed of with wet etching or resist stripping techniques. Dry etching or resist stripping operations use comparatively small amounts of chemicals. 

In this chapter, the motivations to adopt MLR systems for optical e-beam, x-ray, and ion-beam lithographic systems will be given, followed by a survey of published MLR systems. Specific practical considerations such as planarization, pinhole and additive defects, interfacial layer, etch residue, film stress, interference effects, spectral transmission, inspection and resist stripping will be discussed. The MLR systems will be compared in terms of resolution, aspect ratio, sensitivity, process complexity and cost. 

J Resist Stripping. After pattern transfer the resist has to be removed. For the all organic MLR systems, the resist layers can be removed with an O2 plasma if the top surface is not severely altered after an ion implantation or a substrate etching. Otherwise, a solvent treatment followed with clean-... 

With many of the Union Carbide organosilanes investigated, it was difficult to distinguish which materials worked best on freshly 1050°C steam-oxidized (1 m) wafers. Wafers were therefore intentionally soaked in water for 48 h, spun dry , followed by the addition of the organosilane (100%) to the substrate at 3000 rpm for 10 s. The negative resist (1 fim) coated wafers were patterned and processed in a conventional manner, and the oxide was etched in 4 1 buffered NH4F-HF at room temperature until the oxide was removed. Examination (by microscope) of the resist surface for resist lift, followed by resist strip to observe undercutting was performed. 

Resist Stripping Resist Stripping Resist Stripping... 

By dividing one of the signals by the sum of both, one gets the desired dependence on the position P/L. The same concept lies behind the resistive strip anode... 

Figure 4.25 Extraction of one-dimensional position information from a channelplate detector by using a continuous resistive strip anode. If an electron avalanche (shaded circular area) hits the resistive material of the anode, the charges Qt and Q2, collected on the electrical contacts (shaped rectangular areas), are proportional to the distances (P, L)...

Figure 4.26 Possible electronic circuit for deriving one-dimensional position information from a position-sensitive detector with a resistive strip anode. The two charges Q, and Q2 on the ends of the anode are amplified, shaped and converted to a digital signal. The mathematical operations of Q = Qt + Q2 and Q2/Qj are performed electronically, and the result is stored in a histogramming memory from which it is read into the computer. Q2/Q carries the information first that an electron has been detected and second at which position this electron has hit the detector. From [Wac85].

In order to remove the resist after the RIE treatment, wafers were immersed in phenolic-type resist stripper, but the resist as well as the scum could not be stripped. Since a thin silicon oxide layer is formed on the resist surface, and the composition of scum is thought to be silicon oxide as discussed above, it is necessary to remove this silicon oxide layer (scum) prior to the resist removal. Therefore, resist stripping was done in two steps. In a first step the wafer was immersed in buffered hydrofluoric acid solution to remove the silicon oxide and was then treated with conventional resist stripper. 

Production of ZrCl4. Zirconium oxide from the hafnium-separation step was mixed with carbon black, dextrin, and water in proportions 142 Zr02, 142 C, 8 dextrin, and 8 water. The mixture was pressed into small briquettes (3.8 X 2.5 X 1.9 cm) and dried at 120°C in a tray drier. The oxide briquettes were charged to the reaction zone of a vertical-shaft chlorinator lined with silica brick. The charge was first heated by carbon resistance strips until it became conductive. During production, the bed temperature was maintained at 600 to 800 C by an electric current passed directly through the bed. After steady conditions were reached, a reactor 66 cm in diameter produced about 25 kg ZrCLt/h. The ZrCU was condensed from the reaction products in two cyclone-shaped aftercondensers in series, and the chlorine off-gas was removed in a water scrubbing tower. 

In modern times, resist stripping for FEOL layers is typically accomplished with first the application of sulfuric acid and hydrogen peroxide mixture (SPM) solution, followed by the application of ammonium hydroxide and hydrogen peroxide mixture (APM) solution. This combination of solutions is able to strip off almost every kind of resist, except those that have been used in implant processes or have been hard baked or modified by plasma gases during dry etching... 

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