Etchant resistance

Etchant Resistance. Etchant resistance refers to the ability of the resist to withstand the etching environment during the pattern transfer process. The most common method of pattern transfer is wet chemical etching which places emphasis on the adhesion and chemical stability of the resist. Etchant solutions may be either acidic or basic, depending on the type of substrate to be etched. For example, buffered hydrofluoric acid is used to etch Si02. However, lateral penetration of the chemical etchant is significant for thick substrate films and... 

Inlqet ink compositions for etching resist have been reported which can provide cured articles having excellent adhesion to metal plates, etchant resistance and alkali developabiUty, and which can be stably ejected by inkjet printing. 

The combination of a positive charge and reducibility of tetrazolium salts finds use as anticorrosion agents for metals.634,635 The y are components of an oxidant/etchant bath composition for silicon dioxide corrosion-resistant surfaces.636 They are also used as antistatic agents in polyamide... 

Preliminary Examination of PATE Imaging Characteristics. The data herein have shown that PATE resins are easily photolyzed in the deep UV region to form crosslinked films which are of sufficient integrity for photoresists. However, in addition to these film performance properties, a potential resist material must meet other equally important criteria. For example, the masked (unphotolyzed) portion of the resist film must be removed prior to etching, without damage to the cured film. Also, the cured films must withstand an etchant bath. Therefore, since PATE resins seem to meet the necessary requirements of solubility and solvent resistance, investigation of performance under crude simulated processing conditions was undertaken. 

Optical Exposure. Multicomponent LB films were prepared from solutions of novolac/PAC varying in concentration from 5-50 wt% PAC, and transferred at 2.5 -10 dyn/cm. The films were composed of 15 - 20 monolayers, with an average film thickness of 30 nm, as measured by ellipsometry. Exposures were performed with a Canon FP-141 4 1 stepper (primarily g-line exposure) at an exposure setting of 5.2 and with a fine line test reticle that contains line/space patterns from 20 to 1 pm (40 to 2 pm pitch). They then were then developed in 0.1 - 0.2 M KOH, depending on the PAC content The wafers received a 20 min 120°C post development bake to improve adhesion to the Cr. Finally, the Cr was etched in Cyantek CR-14 chromium etchant, and the resist and Cr images were examined by SEM. 

Masking is required for many micromechanical applications. While Si3N4 is only suitable for a small etching depth because of its significant etch rate in HF, noble metals like gold are sufficient mask materials. In contrast to alkaline etchants, organic materials like certain resists or even some adhesive tapes are well suited to protect the silicon surface in isotropic etchants. 

Once the resist has been patterned, the selected regions of material not protected by photoresist are removed by specially designed etchants, creating the resonator pattern in the wafer. Several isotropic (etching occurs in all directions at the same etch rate) and anisotropic (directional) etching processes are available. Wet chemical etching is an isotropic process that... 

Poly(methyl methacrylate) (PMMA) is a classical one-component, positive resist system. PMMA is a single, homogeneous material that combines the properties of excellent film-forming characteristics, resistance to chemical etchants and intrinsic radiation sensitivity. 

COP, the familiar negative e-beam resist developed at Bell Laboratories, is an example of a one-component negative resist system. COP is a copolymer which has excellent film-forming characteristics, resistance to etchants, and intrinsic radiation sensitivity. 

A representative sample of terpolymers was exposed to a variety of etchants for polysilicon and silicon dioxide, and the results are given in Table V. The ratio of the etch rate of the substrate to the etch rate of the resist must be at least 2 1 for the resist to be a viable etch mask. Inspection of Table V, shows that the materials examined are unacceptable for only the QFj — CF3CI (4 1) plasma. The etch rates are comparable to those for PMMA the a-keto-oxime exhibits essentially no effect on that rate and the nitrile affords a slight decrease in the plasma etch rate. The etch rates of some commercially available materials are shown for comparison. 

Figure 1. Cross sections of films etched with liquid or plasma etchants. The isotropic profile is the result of zero overetch and can be generated with liquid or plasma etch techniques. The anisotropic (vertical) profile requires plasma or dry-etch processes. W is the width of the resist pattern. (Reproduced from reference 2. Copyright 1983 American Chemical Society.)...

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