US 2019/0041751 Al  12  Feb. 7,2019  [0050]  A solution oftert-butyl methacrylate (tBMA), (59.  99 g), methacrylic acid (MAA), (29.06 g) and 3-(trimethox› ysilyl)propyl methacrylate (TMSPMA), (20.95 g) dissolved  in 1,3-dioxolane (85.4 g) and a solution of V-65 initiator  (20.95 g) dissolved in 2:1 v/v tetrahydrofurane/acetonitrile  (20.9 g) were both added dropwise over 2 hours to 1,3- dioxolane (199 g) at 75°  C. under a nitrogen blanket. After  addition, the reaction mixture was held at 75°  C. for an  EXAMPLE 1  [0047]  The present compositions provide underlayers hav› ing good etch resistance and high silicon content (s45% Si,  and preferably from 0.5 to 30% Si). The coating layers  comprising the present condensed polymers and underlayers  described herein are wet strippable. By "wet strippable" is  meant that the coating layers and underlayers of the inven› tion are removed, and preferably substantially removed  (;;,;95% of film thickness), by contacting the coating layer or  underlayer with conventional wet stripping compositions,  such as: (1) an aqueous base composition, such as aqueous  alkali (typically about 5%) or aqueous tetramethylammo› nium hydroxide (typically ;;,;5 wt %), (2) aqueous fluoride  ion strippers such as ammonium fluoride/ammonium bifluo› ride mixtures, (3) a mixture of mineral acid, such as sulfuric  acid or hydrochloric acid, and hydrogen peroxide such as a  mixture of concentrated sulfuric acid+30% hydrogen per› oxide, or (4) a mixture of ammonia, water and optionally  hydrogen peroxide. A particular advantage of the present  polymers, and particularly of the present underlayers, is that  they are wet strippable upon contact with a mixture of  [0049]  A further advantage provided by the invention is a  silicon-containing underlayer on a substrate, the silicon› containing underlayer comprising one or more condensed  polymers having an organic polymer chain having pen› dently-bound moieties having an acidic proton and a pKa in  water from -5 to 13 and having pendently-bound siloxane  moieties, wherein the silicon-containing underlayer has a  removal rate of greater than 100 A/sec. when contacted with  a mixture of 30% NH$_{4}$OH/30% H$_{2}$Oiwater in a ratio of  1/1/5 to 1/8/50 wt/wt/wt for a period of time from 30  seconds to 5 minutes at temperature in the range of from  room temperature to 70°  C. Preferably, such silicon-con› taining underlayers have a removal rate of at least 125, more  preferably at least 150, yet more preferably at least 200, and  even more preferably at least 250 A/sec. Preferably, the  polymers comprise as polymerized units one or more second  unsaturated monomers as described above.  [0048]  Another advantage of the present polymer layers is  that they are easily removed to allow re-work of the sub› strate, such as a wafer. In such a re-work process, a com› position described above comprising one or more condensed  polymers of the invention is coated on a substrate. The  coated polymer layer is then optionally soft-baked, and then  cured to form an underlayer. Next, a photoresist layer is  coated on the underlayer, and the resist layer is imaged and  developed. The patterned resist layer and the underlay er may  then each be removed to allow the wafer to be re-worked.  The underlayer is contacted with any of the above-described  wet stripping compositions, such as aqueous tetramethyl› ammonium hydroxide compositions (typically ;;,;5 wt%) and  aqueous fluoride ion strippers such as ammonium fluoride/  ammonium bifluoride mixtures, at a suitable temperature to  remove the underlayer to provide the substrate free, or  substantially free, of underlayer and readily undergo addi› tional re-work as may be necessary. Such re-work includes  coating another layer of the present condensed polymers on  the substrate and processing the polymer coating as  described above.  [0046]  After curing of the coating layer comprising the  condensed polymer to form an underlayer, one or more  processing layers, such as photoresists, hardmask layers,  bottom antireflective coating ( or BARC) layers, and the like,  may be disposed on the underlayer. For example, a photo› resist layer may be disposed, such as by spin coating,  directly on the surface of the underlayer. Alternatively, a  BARC layer may be coated directly on the underlayer,  followed by curing of the BARC layer, and coating a  photoresist layer directly on the cured BARC layer. In  another alternative, an organic underlayer is first coated on  a substrate and cured, a condensed polymer layer of the  invention is then coated on the cured organic underlayer, the  coating layer is then cured to form an underlayer, an optional  BARC layer may be coated directly on the underlayer,  followed by curing of the optional BARC layer, and coating  a photoresist layer directly on the cured BARC layer. A wide  variety of photoresists may be suitably used, such as those  used in 193 nm lithography, such as those sold under the  EPIC™ brand available from Dow Electronic Materials  (Marlborough, Mass.). Suitable photoresists may be either  positive tone development or negative tone development  resists, or may be conventional negative resists. The photo› resist layer is then imaged ( exposed) using patterned actinic  radiation, and the exposed photoresist layer is then devel› oped using the appropriate developer to provide a patterned  photoresist layer. The pattern is next transferred from the  photoresist layer to any optional BARC layer, and then to the  underlayer by an appropriate etching technique, such as dry  etching with an appropriate plasma. Typically, the photore› sist is also removed during such etching step. Next, the  pattern is transferred to any organic underlayer present using  an appropriate technique, such as dry etching with 0 2  plasma, and then to the substrate as appropriate. Following  these pattern transfer steps, the underlayer, and any optional  organic underlayers are removed using conventional tech› niques. The electronic device substrate is then further pro› cessed according to conventional means.  ammonia and hydrogen peroxide. A wide range of ammonia  and water mixtures may be used. A suitable mixture of  ammonia, water and hydrogen peroxide is a mixture of  ammonia+hydrogen peroxide+water in a weight ratio of  1:1:5 to 1:10:50, such as ratios of 1:1:10, 1:1:40, 1:5:40,  1:1:50, or 1:8:50. Preferably, ;;,;97%, and more preferably  ;;,;99%, of the film thickness of the polymer layer or under› layer is removed by contacting the polymer layer or siloxane  underlayer with either (i) mixture of sulfuric acid and  hydrogen peroxide or (ii) a mixture of ammonium hydroxide  and hydrogen peroxide. Such wet stripping of the present  underlayers may be performed at any suitable temperature.  A particular advantage of the present compositions, and  particularly of the present underlayers, is that they are wet  strippable at lower temperatures, such as from 20 to 30°  C.,  preferably from 22 to 28°  C., and more preferably 25°  C.  shorter curing times. Following this curing step, the under› layer surface may optionally be passivated by treatment with  a passivating agent such as a disilazane compound, such as  hexamethyldisilazane, or by a dehydration bake step to  remove any adsorbed water. Such passivating treatment with  a disilazane compound is typically performed at 120°  C. 