Dissolution Of Photoresist Research Articles

Fluorescence Microscopy Characterization of Patterned Nano-Crystalline Quantum Dot Films

This experiment is a continuation of the study concerned with the lift-off based patterning of nanocrystaline quantum dot (NQD) films. The NQD films patterned by lift-off process are analyzed by means of fluorescence microscopy to obtain information about film uniformity, pattern definition accuracy, and average fluorescence intensity. The lift-off process is implemented using wet (acetone immersion) and dry (oxygen plasma) photoresist removing ambient. Methods under investigation were found to perform similarly in terms of pattern resolution accuracy. However, in terms of the uniformity of fluorescence intensity distribution, acetone dissolution of photoresist was found to produce better results.

Efficient stripping of photoresist on metallized wafers by a pause flow of supercritical fluid

Utilization of supercritical fluids (SCFs) is studied here on the premises of a saving of hazardous organic solvents and of the specification for stripping the photoresist (PR) on metallization layers, which is one of the integrated circuit processing modules. By using factorial experimental designs with five factors and four level ranges, this research focuses on determining an optimized recipe with high stripping efficiency and to determine the stripping mechanism. In the case of PR on an aluminum layer, the initial use of the pulse flow mode could increase the extraction ratio remarkably when compared to the conventional continuous flow mode. Based on the limitation of a total volume of 30 mL purging SCF-CO 2 for economical considerations, the optimum conditions can be summarized as follows: 120 °C, oven temperature; 350 atm, CO 2 pressure; 0.2 mL of ethylacetate spiking to SCF-CO 2; 2.0 min, static equilibrium time; and five cycles of dynamic flow pausing. A recovery of 94.6% ( n = 3, RSD = 6.5%) was obtained, while the diffusion of stripped PR from substrate matrix prevailed over the dissolution of binding PR into the SCF medium. In the case of copper, the optimum parameters in a pause flow mode were 140 °C, oven temperature; 500 atm, CO 2 pressure; 0.75 mL, ethylacetate spiking volume; 5.0 min, static time; and six cycles of flow pausing. These extreme parameters still did not produce an SCF environment suitable for diffusion or dissolution mass transfer, and thus a recovery of 76.2% ( n = 3, RSD = 7.5%) was only obtained. Removing PR coated on a Cu layer was harder than that on an Al layer.

Alternative Photoresist Removal Process to Minimize Damage of Low-k Material Induced by Ash Plasma

Dry ashing of photoresist (PR) using oxygen-containing plasma applied subsequently to an etch plasma leads to degradation of porous low-k material. The surface region is substantially depleted in carbon. The low-k film becomes more hydrophilic after being subjected to plasma etch and especially ash process as evidenced by water absorption results. The amount of absorbed water into a 30% porosity film at moisture saturation is estimated to be about 15% of the film volume, which corresponds to 50% of the total pores in the low-k film. A wet, alternative means for PR removal based on dissolution of PR in organic solvents combined with physical forces is presented. Under certain conditions, megasonic cleaning resulted in complete removal of the PR layer without damaging of the dielectric lines. These results suggest that the PR crust is permeable to these solvents and that out-diffusion of dissolved bulk PR also occurred through the crust. Dissolution of bulk PR in organic solvents first makes the PR structure more fragile, then the physical energy helps to remove the remaining crust mechanically without dissolving it. Compared to plasma ashing, solvent strip shows no carbon depletion and no significant increase in k-value.

Microwave-assisted vapor phase dissolution of photoresist and silicon oxide based slurry samples for the determination of trace impurities by high resolution ICP-MS

An effective and contamination free matrix removal method, by closed-vessel microwave assisted volatilization in the presence of vapors of HF and HNO3, for the determination of trace impurities in photoresist samples and slurry with SiO2 particles used for chemical mechanical polishing processes in the electronics industry, is reported. The volatilization of the matrix element from the photoresist and slurry is 99.7% and 99.9%, respectively, using vapors generated from a 1 ∶ 9 ratio of HF ∶ HNO3. The recoveries of Na, Mg, Al, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ag, Cd, Ba and Pb after volatilization of matrix element are in the range 96–108% and 95–105% for the photoresist and SiO2 based slurry, respectively. Determinations are carried out using an inductively coupled plasma mass spectrometer with a sector field (ICP-SFMS). The experimental blanks along with the method detection limits computed based on 3σ variation in blank measurements (n = 5) are also reported.

Evaluating Photoresist Dissolution, Swelling, and Removal with an In Situ Film Refractive Index and Thickness Monitor

Dissolution and removal of photoresist films is performed numerous times during the fabrication of electronic, optical, and mechanical devices and integrated circuits. Information regarding changes in refractive index and film thickness is of interest for the design and modeling of such processes. Spectroscopic reflectometry is a cost-effective technique that has been used to monitor film thickness, but has been limited to applications in which the film refractive index is constant during dissolution, and thus has a known value. This paper extends conventional spectroscopic reflectometry analysis to account for refractive index changes in films during processing. Results obtained by this approach correlate well with spectroscopic ellipsometry measurements. This technique is applied to the dissolution of photoresist in aqueous base solutions, swelling of photoresist in solvent vapor, and removal of photoresist in water-alcohol mixtures, and can similarly be applied to other thin film applications. In addition, the optical properties of fluids such as aqueous and non-aqueous solvents, supercritical or subcritical mixtures, and gas-expanded liquids, which can be used to process thin film materials, can be monitored using spectroscopic reflectometry. © 2004 The Electrochemical Society. All rights reserved.

The percolation approach to the development of pulsed laser exposed positive photoresists

Results of photolithography experiments utilizing the XeCl excimer laser and positive photoresists are reported. Abrupt reciprocity loss resulting in the growth of photoresist contrast and sensitivity was found when laser pulse energy density exceeded a threshold value of about 50 mJ/cm2. Percolation theory is used to derive a model of resist thickness remaining versus dose for development of pulse exposed photoresist. The model accurately describes the change in dissolution of AZ2400 photoresist when the energy is delivered in multiple versus single pulse exposures.