Gate photoresist

Fig. 2. SEM images of TaN gate stack with photoresist masks after etching (a) in pure CI2 and (b) CI2/O2. The experiments were performed at a pressure of lOmTorr, source power of 400W, and bias voltage of -200V.

Figure 15. Simplified process sequence for the fabrication of an NMOS transistor (a) substrate preparation, (b) selective exposure of substrate, (c) mask formation by differential solubility, (d) etching, (e) stripping of resist, (/) doping, (g) reoxidation of silicon surface, (h) formation of gate oxide, and (i) metal deposition and patterning. Abbreviations are defined as follows p-Si, p-type silicon PR, photoresist S, source G, gate and D, drain.

Next, a photoresist material is applied to the structure and the photoresist material is patterned to form a positve mask. The metal layer not protected by the mask is removed by dry etching thereby forming metal interconnects 34. By forming the metal layer on the array prior to applying the photoresist reduces potential surface contamination and increases the integrity of the metal bonds with the respective storage gates 22 and contact pads 84. 

F. H. Bell and O. Joubert, Polysilicon Gate Etching in High Density Plasmas. 5. Comparison between Quantitative Chemical Analysis of Photoresist and Oxide Masked Polysilicon Gates Etched in Hbr/Cl-2/0-2 Plasmas, J. Vac. Sci. Technol. 5 15, 88-97 (1997). 

The purpose of this research was to determine the feasibility of incorporating CPI into field-effect transistors. Due to time limitations and availability of various equipment, source and drains were formed by thermal diffusion rather than by ion implantation as proposed in the preceded discussion. As a result of this slight change in process sequence, metal-gate FETs could be fabricated as a control for the CPI devices. In addition, a non-photosensitive PI was used thus requiring extra photoresist deposition and patterning steps. 

PEDOT-PSS overlayer. The swollen photoresist lifts off along with the PEDOT-PSS overlayer, leaving behind patterns of PEDOT-PSS in the regions that did not originally contain any photoresist. PEDOT-PSS source, drain, and gate electrodes as small as 2 pm were fabricated in this fashion. 

Fig. 4.15. The process flow described in [57]. The gate, gate dielectric, and source/drain layers are photolithographically patterned. The gate dielectric is passivated using octadecyltrichlorosilane, and the semicondnctor is deposited. A chromate sensitized aqueous polyvinyl alcohol based photoresist is then used to pattern the semiconductor. Uncrosslinked resist is developed with water and the exposed pentacene is etched using an oxygen plasma.

Fig. 5.12. A schematic showing the self-aligned process flow implemented in the parylene encapsulation process. An extra exposure step and mask is required to fill in interconnect shadowed by the gate layer, but these exposures are performed on the same photoresist and the total number of layers remains the same.

Because the initial surface is glass, the gate can be deposited using sputtering and plasma processes can be used to remove the photoresist instead of solution processes. 

Examples of the patterns fabricated by this machine are a 40 nm-linewidth linear pattern (Fig. 1.28a), a high-aspect-ratio pattern (Fig. 1.28b), a pattern with a minimum linewidth of 22 nm realized by making high-resolution photoresist (Fig. 1.28c), two-dimensional arrays of rings and disks (Fig. 1.28d, e), and so on [53]. This machine has been made available for public use since April 2006. Examples of its use include the fabrication of a two-dimensional array of room-temperature operated nanophotonic NOT gates composed of InAs QDs (refer to Fig. 1.11), linear and curved Si optical waveguides, and so on. 

After development of the photoresist, the n" a-Si and the i a-Si are etched away except for the semiconductor layers on the gate electrodes (d). An ITO layer is deposited and patterned to form drain, source and pixel electrodes (e). The n" a-Si and a part of the i a-Si are etched by the reactive ion etching method (f). In this way, the two-mask-step TFTs is obtained. The SiN on the gate electrodes to be connected to peripheral driver ICs is etched away after the liquid crystal cell assembly process. 

The polysilicon (poly) gate etch process is shown schematically in Fig. 13.12. Photoresist (PR) etching and polysilicon etching are the most critical batch steps for... 

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