Equipment and method for measuring silicon concentration in phosphoric acid solution
Disclosed is equipment for measuring a silicon concentration in a phosphoric acid solution under use as an etching solution during operation of a semiconductor substrate processing system. The equipment is provided with at least a reaction tank and a concentration-measuring tank. The reaction tank includes a reaction unit for adding hydrofluoric acid to a predetermined constant amount of the phosphoric acid solution drawn out of the semiconductor substrate processing system to form a silicon fluoride compound and then causing the silicon fluoride compound to evaporate. The concentration-measuring tank comprises a hydrolysis unit for bubbling the silicon fluoride compound, which has evaporated from the reaction tank, through deionized water to hydrolyze the silicon fluoride compound and a measurement unit for determining a change rate of silicon concentration in the deionized water subsequent to the bubbling. Also disclosed is a method for measuring a silicon concentration in a phosphoric acid solution under recirculation and use as an etching solution in a semiconductor substrate processing system in operation.
1. Equipment for measuring a silicon concentration in a phosphoric acid solution under use as an etching solution during operation of a semiconductor substrate processing system, said measuring equipment comprising:
a reaction tank containing phosphoric acid solution comprising silicon compounds that is drawn from the processing system into the reaction tank;
a concentration-measuring tank containing deionized water, said concentration-measuring tank being separate from the reaction tank; and
a gas feed line connected between the reaction tank and the concentration-measuring tank,
wherein the reaction tank comprises:
a phosphoric acid solution feed line connected between the reaction tank and a phosphoric acid solution recirculation line of the processing system, to feed the phosphoric acid solution comprising silicon compounds that is drawn from the processing system into the reaction tank;
a hydrofluoric acid feed line connected to the reaction tank, to feed hydrofluoric acid into the reaction tank;
a means for evaporating, into silicon fluoride gas, silicon fluoride compounds formed by reaction between the phosphoric acid solution and the hydrofluoric acid inside the reaction tank; and
a means for feeding an inert gas from a lower part of the reaction tank into the phosphoric acid solution in the reaction tank,
wherein the gas feed line feeds the silicon fluoride gas from the reaction tank into the concentration-measuring tank,
and wherein the concentration-measuring tank comprises:
a deionized water feed line connected to the concentration-measuring tank, to feed the deionized water into the concentration-measuring tank;
a means for bubbling connected to the gas feed line and arranged inside the concentration-measuring tank, that causes the silicon fluoride gas from the gas feed line to bubble into the deionized water in the concentration-measuring tank, to hydrolyze the silicon fluoride gas in the deionized water; and
a means for determining a change rate of silicon concentration in the deionized water in the concentration-measuring tank subsequent to said bubbling.
2. The equipment for measuring according to claim 1 , wherein said reaction tank further comprises a means for controlling temperature of contents of the reaction tank.
3. The equipment for measuring according to claim 2 , wherein the means for controlling temperature controls the temperature at a range of 70 to 180 degrees C.
4. The equipment for measuring according to claim 3 , wherein the means for controlling temperature is a heater arranged inside the reaction tank.
5. The equipment for measuring according to claim 1 , wherein said means for measuring silicon concentration in the deionized water in the concentration-measuring tank comprises an electric conductivity sensor.
6. The equipment for measuring according to claim 1 , wherein the reaction tank further comprises a liquid level sensor arranged inside the reaction tank to enable feeding of a predetermined constant amount of the phosphoric acid solution in the reaction tank.
7. The equipment for measuring according to claim 1 , wherein the concentration-measuring tank further comprises a liquid level sensor arranged inside the concentration-measuring tank to enable feeding of a predetermined constant amount of the deionized water in the concentration-measuring tank.
8. The equipment for measuring according to claim 1 , wherein the concentration-measuring tank further comprises a liquid-temperature-measuring thermocouple for measuring the temperature of the deionized water in the concentration-measuring tank.
9. Equipment for measuring a silicon concentration in a phosphoric acid solution under use as an etching solution during operation of a semiconductor substrate processing system, said measuring equipment comprising:
a reaction tank containing phosphoric acid solution comprising silicon compounds that is drawn from the processing system into the reaction tank;
a concentration-measuring tank containing deionized water, said concentration-measuring tank being separate from the reaction tank; and
a gas feed line connected between the reaction tank and the concentration-measuring tank,
wherein the reaction tank comprises:
a phosphoric acid solution feed line connected between the reaction tank and a phosphoric acid solution recirculation line of the processing system, to feed the phosphoric acid solution comprising silicon compounds that is drawn from the processing system into the reaction tank;
a liquid level sensor arranged inside the reaction tank to enable feeding of a predetermined constant amount of the phosphoric acid solution in the reaction tank;
a hydrofluoric acid feed line connected to the reaction tank, to feed hydrofluoric acid into the reaction tank;
a means for evaporating, into silicon fluoride gas, silicon fluoride compounds formed by reaction between the phosphoric acid solution and the hydrofluoric acid inside the reaction tank;
a heater for controlling the temperature of contents of the reaction tank at a range of 70 to 180 degrees C.; and
a means for feeding an inert gas from a lower part of the reaction tank into the phosphoric acid solution in the reaction tank,
wherein the gas feed line feeds the silicon fluoride gas from the reaction tank into the concentration-measuring tank,
and wherein the concentration-measuring tank comprises:
a deionized water feed line connected to the concentration-measuring tank, to feed the deionized water into the concentration-measuring tank;
a liquid level sensor arranged inside the concentration-measuring tank to enable feeding of a predetermined constant amount of the deionized water in the concentration-measuring tank;
a liquid-temperature-measuring thermocouple for measuring the temperature of the deionized water in the concentration-measuring tank;
a means for bubbling connected to the gas feed line and arranged inside the concentration-measuring tank, that causes the silicon fluoride gas from the gas feed line to bubble into the deionized water in the concentration-measuring tank, to hydrolyze the silicon fluoride gas in the deionized water; and
a means for determining a change rate of silicon concentration in the deionized water in the concentration-measuring tank subsequent to said bubbling, said means for determining a change rate comprising an electric conductivity sensor.