HIRANUMA APPLICATION DATAElectric &Electronics

Automatic Titrator

Data No.

F10Apr. 5,
2019

Determination of alkaline component inphotoresist remover solution(Determination of carbonates with barium chloride addition method)

1. Abstract
Strong alkaline solution is used as remover for residual photoresist on the substrate after the developmentof the substrate for liquid crystal display instrument etc. The composition depends on the intended use but
sodium hydroxide, potassium hydroxide, and tetramethylammonium hydroxide (TMAH) are used as remover.
TMAH can be determined by potentiometric titration with hydrochloric acid standard solution. TMAH
could absorb carbon dioxide gas and generate carbonates, it indicates another inflection point at pH around 4
on the titration with hydrochloric acid standard solution. This report introduces an example of fractional
determination for TMAH and carbonates. Barium chloride is added to determine carbonates; the precipitate ofbarium carbonate is generated on this method (formula (1)).

[N(CH3)4]2CO3 ＋ BaCl2→[N(CH3)4Cl]2 ＋ BaCO3↓･･･(1)

This solution is titrated with hydrochloric acid. Only TMAH is determined at the first inflection point,and barium carbonate is determined at the second inflection point on the titration.

N(CH3)4OH ＋ HCl→ N(CH3)4Cl ＋ H2O
BaCO3 ＋ 2HCl → BaCl2 ＋ CO2 ＋ H2O･･･(2)･･･(3)The reactions between TMAH and hydrochloric acid is described in formula (2), barium carbonate andhydrochloric acid is shown in formula (3). It reaches the endpoint at pH around 9 and 4 on the reaction (2) and(3), respectively. The titrant volume to determine carbonates gets twice on this method compared with themethod without the addition of barium chloride. This method is useful especially for a sample containing lessamount of carbonate.

2. Configuration of instruments and reagents(1) Configuration of instruments
Main unit: Hiranuma Automatic Titrator COM series

Electrodes: Glass electrodeGE-101B

Reference electrodeRE-201Z*The following electrodes are usable instead of the above electrodes.
・Glass reference combination electrode GR-501BZ…Fixed sleeve type・Glass reference combination electrode GR-511BZ…Moveable sleeve type(2) Reagents
Titrant: 0.5 mol/L Hydrochloric acid standard solution

Additive solution: 10 % Barium chloride solution
Dissolve 11.7 g of barium chloride dihydrate in DI water and dilute to 100 mL.

3. Measurement procedure(1) Take about 25 g of sample into a 50 mL beaker and weigh accurately.
(2) Add 10 mL of 10 % barium chloride solution.
(3) Immerse electrodes and start titration with 0.5 mol/L hydrochloric acid standard solution.

4. Measurement conditions and results
Example of titration condition(1) Titration of TMAH
Cndt No.
MethodBuret No.
Amp No.
D. Unit
S-Timer
C.P. mLT Timer
D.P. mLEnd Sens
Over mLMax.Vol.

1Auto

11pH
511.5
50
3000
020sec
mLsec
mL
mL
mL

ConstantNo.
SizeBlank
Molarity
FactorKL
Unit
FormulaDecimal Places
Auto In Pram.

125.1046 g0 mL
0.5 mol/L
1.005
91.15
0.000%

Mode No.
Pre Int
Del K
Del Sens
Int Time
Int Sens
Brt Speed
Pulse

2209023220

Mode No.
Pre Int
Del K
Del Sens
Int Time
Int Sens
Brt Speed
Pulse

2300023220sec
mV
sec
mV

(D-B)*F*M*K/(S*10)
4Non(2) Titration of carbonates
Cndt No.
MethodBuret No.
Amp No.
D. Unit
S-Timer
C.P. mLT Timer
D.P. mLEnd Sens
Over mL
Max.Vol.

2Auto1
1pH00005000
0.1
20sec
mL
sec
mL
mL
mL

ConstantNo.
SizeBlank
Molarity
FactorKL
Unit
FormulaDecimal Places
Auto In Pram.

225.1046
00.5
1.005
104.15
0%

g
mL
mol/L

(D-B)*K*F*M/(S*10)
4NonsecmV
secmVMeasurement results
Measurement results of TMAH
Number of
Measurement

Size(g)Titrant
Volume (mL)Concentration
(%)

123

25.1046
25.1382
25.1796

12.51412.51312.534

2.28322.27992.2800Avg.
SDRSD

Statistic
calculation

2.281 %
0.0019 %0.08 %

Measurement results of carbonates<Expanded figure>

Number ofMeasurement
123Size(g)25.1046
25.1382
25.1796

Statistic
calculation

Titrant
Volume (mL)
0.605
0.621
0.624

Avg.
SDRSD

Concentration(%)
0.12610.12930.12970.128 %
0.0020 %1.54 %

Example of titration curve

5. Note(1) Measurement method
TMAH is strong alkaline reagent which absorbs carbon dioxide gas in air and generates carbonates. Purgingair on sample solution with nitrogen gas can reduce the influence of carbon dioxide on the titration. Using
air passed through soda lime absorption column instead of nitrogen gas also has a positive effect.
Water wasn't added to sample; non-diluted sample was titrated directly in this measurement. Please pay
attention to carbonic acid in the water when it is added for the sample dilution before the titration.
(2) Sample measurement without addition of barium chloride
Barium chloride was added to the sample solution to determine the carbonates. The measurement is possible
without barium chloride when the sample contains a certain amount of carbonate. (Please refer toapplication note F9 regarding the method without the addition of barium chloride.)
Keywords: Tetramethylammonium hydroxide, TMAH, Remover, Carbonates, Neutralization titration,
Barium chloride, Barium carbonate*Some measurement would not be possible depending on optional configuration of system.