Reduction of photoresist consumption to reduce costs while maintaining resist coating quality is becoming a major challenge for process and equipment engineers in the semiconductor industry. This challenge can be met by reducing dispense nozzle diameter to maintain a constant dispense rate at a reduced dispense volume. In this study, two small dispense nozzle sizes (0.5 and 0.6 mm in diameter) and two resist dispense volumes (0.4 and 0.5cc per coating) were evaluated during the resist spin coating process. Stability tests of five resist thickness means and ranges of three photo resists types with various resist viscosities were performed using small dispense nozzles and small resist dispense volumes. Each stability test consisted of both 25 wafer continuous resist coats and one wafer per coating for 15 days. Coat defects from the coat process using a small dispense nozzle and small resist dispense volume were analyzed on the layers of Island, Poly, Metal and Contact in a manufacturing fab. The effect of the resist coat process using a small dispense nozzle and a small resist dispense volume on critical dimension (CD) performance of Island, Poly, Metal and Contact layers before and after etch was reported. Resist thickness uniformity data, coating defect data and CD data from the small dispense nozzle size and reduced resist dispense volume coating process were also compared with a normal resist coating process with dispense nozzle size of 1.5mm and resist dispense volume of 0.6 to 0.75cc per coating.
As critical dimensions (CD) in semiconductor devices decrease past the 130 nm node, the requirements of photoresists to meet process and manufacturing needs increase significantly. This is reflected in a dramatic increase in photoresist cost. Reduction of photo resist consumption to reduce costs while maintaining resist coating quality is becoming a major challenge for process and equipment engineers in semiconductor industry. In this study, six small dispense nozzle sizes (0.5, 0.6, 0.7, 0.8, 0.9 and 1.0mm) were evaluated during the spin coating process. The maximum acceptable resist dispense time (the longest time with continuous resist flow for a given amount of resist at a given dispense distance) was determined. It was found that maximum acceptable resist dispense time was affected primarily by dispense nozzle size and material, pump function and resist properties such as viscosity. The relationship between minimum acceptable dispense rate (based on maximum acceptable resist dispense time) and various dispense nozzle sizes has been determined. The minimum acceptable resist dispense rate for a given dispense nozzle size did not appreciably change no matter what resist volume was used. As expected, the results indicated that maximum acceptable resist dispense time increased as dispense volume increased for a given nozzle size. The resist coating thickness mean and range of six resists with viscosity from 2 cp to 30 cp was reported by use of several combinations of resist dispense volume and dispense nozzle size. Resist coating test indicates that resist consumption can be reduced to 0.4 to 0.5 ml per coating with acceptable thickness mean and range for resists of viscosity less than 10 cp, and 0.9 to 1.0 ml per coating for resists with viscosity greater than 10 cp.
RRC (Reducing Resist Consumption) process is widely used in the Semiconductor industry to decrease the cost of photo resist per wafer. However, the process is often accompanied with various coating defects that make it difficult to improve final yield and further reduce resist cost per wafer. Deep ultraviolet (DUV) bottom anti-reflective coating is critical to critical dimension (CD) control and is used for most critical layers like Poly, STI and Contact layers. This paper will present a novel double pre-wet RRC process to reduce both coating defects and resist consumption of BARC. The relationship between resist consumption per coating and thickness uniformity (mean and range) of the new process was evaluated. The stability test results of the new process shows acceptable manufacturing results. Coating defects from double pre-wet RRC process were analyzed and compared with the normal coating process without RRC. The effect of DUV BARC coating performed by the double pre-wet RRC process on critical dimension (CD) performance of Island, Poly and Contact layer was also reported.
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