Substrate treating apparatus and method
View Patent ↗A substrate treating apparatus for treating substrates with a treating solution having a mixture of a chemical and a diluent. The apparatus includes a treating tank for storing the treating solution, a heating device for heating the treating solution, a supply pipe for supplying a gas at a fixed flow rate, the supply pipe having a detecting end at a predetermined depth in the treating tank, a pressure detecting device for detecting a pressure in the supply pipe, a converting device for converting the pressure detected by the pressure detecting device into a voltage, a storage device for storing, as a reference voltage, a voltage received from the converting device when a reference liquid at a reference temperature is stored in the treating tank, and a computing device for deriving an actual specific gravity of the treating solution from the reference voltage stored in the storage device, and a treatment voltage received from the converting device when the treating solution stored in the treating tank has been heated to a treating temperature by the heating device.
1. A substrate treating method for treating substrates with a treating solution having a mixture of a chemical and a diluent, comprising:
a step of deriving an actual specific gravity of the treating solution from a reference voltage obtained by a pressure detecting device according to a pressure at a predetermined depth in a treating tank when a reference liquid at a reference temperature is stored in the treating tank in advance of treatment, and a treatment voltage obtained by the pressure detecting device when the treating solution stored in the treating tank has been set to a treating temperature;
a step of determining a reduced actual specific gravity by reducing said actual specific gravity to a specific gravity in time of a measuring temperature when measuring a specific gravity-concentration characteristics of the treating solution;
a step of deriving a reduced concentration of the treating solution from said reduced actual specific gravity and said specific gravity-concentration characteristics; and
a step of adjusting the treating solution based on said reduced concentration.
2. A method as defined in claim 1 , wherein said treating temperature is in a range of 140 to 170° C.
3. A method as defined in claim 1 , wherein said treating solution has phosphoric acid diluted with deionized water, and said reference liquid is deionized water.
4. A method as defined in claim 1 , wherein the step of determining said reduced actual specific gravity is executed to determine said reduced actual specific gravity at the treating temperature by multiplying the actual specific gravity obtained by said actual specific gravity calculating device, by a factor set beforehand according to a ratio between the actual specific gravity of the treating solution at the treating temperature and a measured specific gravity obtained by a specific gravity meter from said treating solution at a measurement temperature.
5. A method as defined in claim 4 , wherein said treating temperature is in a range of 140 to 170° C.