Baking wafers

Wafer batter does not ordinarily contain fat or oil. However, on occasion a small amount of oil is included in the batter, to facilitate release of the baked wafer from the griddle. The amount used is just enough to effect release (perhaps 0.5% of total batter weight). An oil with high oxidative stability would give the best lubrication in this application. 

A SU8-100 photoresist solution (PRS) was used in all of the procedures. In order to make the three-layer photoresist patterns for the top master, the first layer was coated as 50 pm thick on a 100 mm diameter silicon wafer 2mL PRS was spun at 500 rpm for 10 s following at 5000 rpm for 30 s with a spin coater. The spin-coated wafer was baked at 60 °C for 10 min, and then at 95 °C for 30 min. After baking, the photomask image (Figure 4.5A) was patterned on the first layer using a UV lamp (370 nm) in a mask aligner for 30 s. On the exposed first layer without a developing step, the second layer for the profile of the ESI emitter was coated as 200 pm thick 4mF PRS was spun at 500 rpm for 20 s followed by 2000 rpm for 30 s. The wafer coated with two layers was baked at 60 °C for 20 min, and then at 95 °C for 60 min. The baked wafer was exposed with a second... 

Wafers are made by depositing batter mix onto hot baking plates. The baked wafer sheets are removed from the plates while still soft and... 

Bake wafer at 200°C for 30 minutes Spin coat photoresist Soft bake at 90 C... 

A.irbome Basic Chemical Contamination. A critical, and at-first pu22ling problem, was encountered during early manufacturing trials of CA resists. Sporadically, severely distorted resist profiles would be formed in positive-tone CA resists, displaying what seemed to be a cap on the upper surface of the resist image (Fig. 26). In severe cases this cap or T-top would appear as a kin or cmst over the entire wafer surface that prevented development of the pattern. The magnitude of the effect varied dramatically between laboratories and appeared to grow more severe as the time interval between exposure and post-exposure bake was increased. 

All wafers have in common that they are baked to a low moisture content, as are biscuits. Wafers readily pick up moisture at UK ambient conditions and become soft unless they are protected from moisture. Wafers will normally soften more rapidly than biscuits. 

Wafers can be either yeast raised or chemically raised, e.g. by baking powder. Yeast raised wafers do not contain much sugar after fermentation. 

Acid Concentration Required for Crosslinking Resist Films. The strong acid catalyzed reaction of methylated melamine 1 with novolak in a film was studied first in order to estimate the amount of acid generated in experimental AHR resists upon exposure. Incremental amounts of a 1% solution of p-toluenesulfonic acid (pTSA) were added to a resist solution which contained no RSAG. The solutions were coated onto wafers and subjected to a typical bake cycle. The dissolution rate... 

Negative two-layer resist. A cresol novolac resin (Alnovol PN-430) was spin-coated on a silicon wafer and baked at 80V, for one minute on a hot plate. The silicon wafer was set on a spin-coater and a photosensitive solution consisting of D1 (3 wtlfc), PVP (5 wt%), acetic acid (46 wt%), and water (46 wt%) was... 

Photoacid generator. D1 (4 wt%) was mixed with poly(glycidyl methacrylate) (PGMA) (20 wt%) in ethyl cellosolve acetate. The mixture was spin-coated on a silicon wafer and baked at 80V for 1 minute. Exposure was performed with a 600-W Xe-Hg lamp in conjunction with a UVD2 filter. The resist was developed in a mixture of methyl ethyl ketone to ethanol (7/1 w/w). 

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. 

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