1. Preface:

Photolithography is a key process in integrated circuit (IC) manufacturing, accounting for 40% of the chip manufacturing process

50% of the schedule. In the photolithography process, not only is a photolithography machine required, but also a key material - photoresist. Photolithography is one of the most critical materials in the semiconductor industry. In the entire process of integrated circuit manufacturing, photolithography technology accounts for about 35% of the total chip manufacturing cost and is the most core process in semiconductor manufacturing.

Photoresist is a complex mixture composed mainly of organic solvents, polymer resins, photoacid agents (PAG), and additives. Among them, photoacid is a key component of photoresist, which plays a decisive role in the sensitivity and resolution of photoresist. The purity and impurity control of photoacid agents have a significant impact on the yield of photoresist and the entire semiconductor product. The common composition of photoacid agents is the cationic part of triphenylsulfide and the anionic part of polyfluorosulfonate. The anionic part has almost no UV absorption, and the electrospray detector (CAD) does not rely on compounds to have optical activity, making it an ideal detector for controlling the quality of photoacid agents.

This application takes trifluoromethylsulfonate as an example to explore the feasibility of CAD for quality control of photoacid agents.

The charged spray detector (CAD) is a new universal detector developed in recent years. Its detection has nothing to do with the molecular structure of the tested substance, and the tested substance does not need to be ionized. As long as the tested substance belongs to semi volatile or nonvolatile compounds, CAD can be used for detection. Meanwhile,

CAD is a quality sensitive detector, and the response value of the substance being tested is determined by the absolute mass of the sample being tested. As long as the absolute mass of the sample being tested is consistent, the measured response values tend to be similar and can achieve lower detection limits and higher sensitivity.

Electric fog detector (CAD) is a significant technological achievement achieved by the R&D team of Yingmai Instrument after years of dedicated research and repeated experiments. This detector adopts advanced electrical and atomization technology, which can achieve high sensitivity and precision detection of trace samples.

2. Instruments and materials:

Instrument: Agilent 1200 liquid chromatography+CAD detector (Ingrid Instrument, model: CADetector a1)

Reagents: Pure water (Watsons distilled water), Acetonitrile (chromatographically pure), Formic acid (analytically pure) Sample: Trifluorobutyl sulfonic acid triphenylsulfonium salt.

3. Method and Results:

3.1 Chromatographic conditions:

Chromatography column: InfinityLab Poroshell 120 EC-C18 Column temperature: 55 ℃ Flow rate: 0.4mL/min Injection volume: 5 μ L

Mobile phase A: 0.2% formic acid aqueous solution Mobile phase B: acetonitrile

Gradient condition elution

CAD conditions:

Instrument model: Yingmai Instrument CADetector a1 Drift tube temperature: 40 ℃ Atomization airflow: 3L/min Polarization current: 1 μ A Polarization airflow: 1L/min

3.2 Sample Preparation:

Diluent: Prepare 2000 µ g/mL of trifluoromethanesulfonic acid triphenylsulfonium salt mother liquor with methanol and methanol water (1:1), and dissolve it in pure methanol solution. Dilute the mother liquor step by step with a methanol water (1:1) solution to prepare concentrations of 1, 2, 5, 10

Series solutions of 100 and 1000 µ g/mL.

3.3 Experimental results:

3.3.1 Applicability of the Method

Under the conditions of this method, the retention time of cations and anions is appropriate, and the separation degree, peak shape, and peak response are all good

3.3.2 Method Sensitivity

1 µ g/mL sample, inject 5 μ L; Triphenylsulfide has a good response with a signal-to-noise ratio of 1097.4 (ASTM method); Trifluorobutyl sulfonate has a good response with a signal-to-noise ratio of 122.9 (ASTM method)

3.3.3 Repeatability

Repeatability for 6 consecutive injections, RSD% of triphenylsulfide peak area is 0.880; Peak area of trifluoromethanesulfonic acid group

The RSD% is 1.222%, all less than 2.0%, indicating good repeatability of the method.

3.3.4 Linear

The concentration is 1-1000 µ g/mL, and the correlation coefficient R of triphenylsulfur is 0.99995; The correlation coefficient R of trifluoromethanesulfonic acid is 0.99976, indicating good linearity and a wide linear range.

4Experimental conclusion:

This article uses HPLC-CAD method to analyze anions in photoacid samples. This scheme has high sensitivity, good ion separation and repeatability, wide linear range, and can be used as an evaluation method for photoacid agents.

HPLC-CAD method is easy to operate, highly specific, and sensitive, and can be used for quality control and method evaluation of photoacid agents.