Page 302 - Elements of Chemical Reaction Engineering 3rd Edition

274 Collection and Analysis of Rate Data Chap. 5

Ultraviolet radiation

E

Photoresist

Silicon dioxide

(0) Silicon

Unexposed Photoresist After HF etching

(C)
Figure P5-12

exposed SiO, . It is extremely important to know the kinetics of the reaction
so that the proper depth of the channel can be achieved. The dissolution reac-
tion is
SiO, + 6HF+ H,SiF, + 2H,O

From the following initial rate data, determine the rate law.

Erching Rare (ndmin) I 60 200 600 lo00 1400
1
HF (wt %) 8 20 33 40 48

A total of 1000 thin wafer chips are to be placed in 0.5 dm3 of 20% HE If a
spiral channel 10 pm wide and 10 m in length were to be etched to a depth
of 50 pm on both sides of each wafer, how long should the chips be left in
the solution? Assume that the solution is well mixed. (Am.: 330 min)
P5-138 The oxidation of propene (P) to acrolein (A) was carried out over a Mo-Pr-Bi
catalyst [Znd. Eng. Chem. Res., 26, 1419 (1987)l.
CHJH = CH, + O,+ CH, = CHCHO + H,O

It has been proposed to correlate the data using the power law model for the
rate law [cf. Equation (5-2)].

racrolel" = kPP"P&