Novel Crosslinking Method for Negative Tone Photoresist having Pendant Carboxyl Moieties

Liu, Jui-Hsiang; Shih, J.R.

doi:10.1088/0954-0083/13/1/301

Cited by 6 publications

(2 citation statements)

References 9 publications

(7 reference statements)

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“…We hypothesized that HF diffusion was the dominant reason for pits and that the hydrophobicity of the dehydrated PR could prevent outcomes effectively. Through the thermal curing at a high temperature, dehydration and cross-linking arose and the hydrophilicity of the PR decreased significantly [30,31]. Instead of thick Au film, the cured PR was expected effectively to prevent the creation of pits.…”

Section: Effect Of Curing Of the Photoresistmentioning

confidence: 99%

“…Compared to uncured PR, 5 min of curing time removed 36% of the pits, 10 min removed 77% These results suggest that the curing process transformed the property of the PR from hydrophilic to the hydrophobic, and blocked the diffusion of the hydrophilic HF solution and the Cr/Au etchants. Baking of the PR at a high temperature was reported to trigger the cross-linking of the carboxyl group, cause dehydration and increase the hydrophobicity of the PR dramatically [30,31]. The hydrophobic cured PR appeared to block the diffusion of HF and of the Cr and Au etchants effectively.…”

Section: Curing Timementioning

confidence: 99%

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Deep wet etching of borosilicate glass and fused silica with dehydrated AZ4330 and a Cr/Au mask

Jin¹,

Yoo²,

Bae³

et al. 2013

J. Micromech. Microeng.

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This research highlights a superior glass-wet-etch technique which enables a glass wafer to be etched for more than 20 h in 49 wt% hydrofluoric acid (HF) only with Cr/Au film and a common positive photoresist, AZ4330. We demonstrated that pits on the wet-etched glass wafer were generated not only due to HF diffusion through the Cr/Au film but also due to pinholes on the Cr/Au films created by the diffusion of the Cr/Au etchant through a photoresist etching-mask during the Cr/Au wet etching process. These two types of diffusion, HF diffusion and Cr/Au etchant diffusion, were eliminated by the thermal curing of a photoresist (PR), AZ4330, before the Cr/Au wet etching process. The curing process allowed the PR to dehydrate, increased the hydrophobicity, and prevented the diffusion of the hydrophilic HF and Cr/Au etchant. Optimization of the curing process was performed, showing that curing at 130 °C for 20 min was the proper condition. With the optimized process, a 525 µm thick borosilicate glass wafer was penetrated with 49%wt HF. A fused silica wafer 525 µm thick was also wet-etched and penetrated with 49 wt% HF at 10 h. Moreover, no pits were found in wet etching of the fused silica for 20 h in 49 wt% HF. These findings demonstrate that the proposed technique allows the wet etching of a glass wafer for more than 20 h in 49%wt HF, the best result thus far. We fabricated a glass substrate with a 217.0 µm deep cavity and a penetrating through-via using the proposed technique, proving the feasibility of the product as an optical component with a surface roughness of 45.5 Å in the cavity.

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Section: Effect Of Curing Of the Photoresistmentioning

confidence: 99%

Section: Curing Timementioning

confidence: 99%

Deep wet etching of borosilicate glass and fused silica with dehydrated AZ4330 and a Cr/Au mask

Jin¹,

Yoo²,

Bae³

et al. 2013

J. Micromech. Microeng.

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show abstract

Synthesis and characterization of novel copolymers with acid‐labile ketal moieties derived from camphor

Liu

Wang

2003

J of Applied Polymer Sci

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Novel diastereomeric acrylic ketal monomers derived from (ϩ)-camphor and (Ϯ)-camphor were synthesized. To investigate the applications of the camphor derivatives on positive-tone photoresists, the acrylic ketal monomers were copolymerized with methyl methacrylate, methacrylic acid, and n-butyl methacrylate. The optical activities of the chiral monomers and polymers were all evaluated. After UV irradiation and postexposure baking, the optical activity of the polymers decreased because of the decomposition of the acid-labile pendant chiral groups. The existence of alicyclic camphyl groups increased the etching resistance of the photoresists. The thermogravimetric properties of the copolymers, the exposure curves, the lithographic evaluation of the positive-tone photoresists, and the effects of alicyclic groups on the plasma etching resistance of the copolymers were all investigated. A resolution of a lineand-space pattern of 0.3 m was achieved. Acid-catalyzed dehydration crosslinking was also found in this system. Sufficient UV irradiation and heat treatment could cause the acid-catalyzed dehydration crosslinking of pendant carboxyl groups and thereby increase the efficiency of the thermal resistance of the polymers.

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Crosslinkable positive‐tone photoresist comprising polymers with pendant carboxyl groups

Liu

Shi

Chen

2001

J of Applied Polymer Sci

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Poly(methacrylic acid-co-t-butylmethacrylate-co-bornylmethacrylate) was synthesized and its application to a crosslinkable positive photoresist was investigated. The existence of pendant alicyclic bornyl groups increased the thermostability of copolymers; however, a decrease in the acid-catalyzed deprotection of pendant t-butyl groups led to a decrease in the sensitivity of the positive-tone photoresist. The thermostability of the relief polymeric patterns of the positive-tone photoresist was appreciably improved effectively because of the acid-catalyzed dehydration crosslinking of pendant carboxyl groups. Thermogravimetric properties of binder resins, exposure characteristics, and sensitivity and resolution of the photoresist were all investigated. Lithographic evaluation of the curable positive-tone photoresists was also estimated.

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Novel Crosslinking Method for Negative Tone Photoresist having Pendant Carboxyl Moieties

Cited by 6 publications

References 9 publications

Deep wet etching of borosilicate glass and fused silica with dehydrated AZ4330 and a Cr/Au mask

Deep wet etching of borosilicate glass and fused silica with dehydrated AZ4330 and a Cr/Au mask

Synthesis and characterization of novel copolymers with acid‐labile ketal moieties derived from camphor

Crosslinkable positive‐tone photoresist comprising polymers with pendant carboxyl groups

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