Hey Quing, Try increasing the exposure time. It is not easy to get perfect straight walls using AZ 4620. The bottom layers are not exposed very well leading to the unmasked resist staying on after development that causes less than 90 deg angles of the sidewalls. Sreeram ---------------------------------------------------------------------------- ----------------- CONFIDENTIAL AND PRIVILEGED INFORMATION ------------------ This email, including attachments, contains information that is privileged, confidential or subject to non-disclosure agreements or intellectual property laws. This email, including attachments, constitutes non-public information intended to be conveyed only to the designated recipient(s). If you are not the intended recipient, please delete this email, including attachments, and notify the sender by return mail, email, or by calling (ALL CONTACT INFORMATION LISTED BELOW). The unauthorized review, use, dissemination, distribution, or reproduction of this email, including attachments, is prohibited and may be unlawful. APPLIED IMAGE Group / Optics subsidiary 4400 South Santa Rita Avenue Tucson, AZ 85704 phone: 520-806-3800 fax: 520-806-3899 ----------------- CONFIDENTIAL AND PRIVILEGED INFORMATION ------------------ ----------------------------------------------------------------------------