Electric heating – Heating devices – With power supply and voltage or current regulation or...
Utility Patent
1999-03-01
2001-01-02
Paschall, Mark (Department: 3742)
Electric heating
Heating devices
With power supply and voltage or current regulation or...
C219S121580, C219S494000, C118S724000, C438S715000
Utility Patent
active
06169274
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a heat treatment apparatus and a heat treatment method for heating or cooling a substrate, for instance, a resist coated semiconductor wafer.
In processes of semiconductor device fabrication, the photolithography technology is used. In the photolithography technology, resist is coated on a surface of a semiconductor wafer (referred to as “a wafer” hereinafter), the coated resist is exposed to a predetermined pattern and developed. Thus, the predetermined pattern resist film is formed on the wafer and moreover the predetermined pattern circuit is formed by a film-forming and etching treatment.
In the process of forming a resist film, one of the important problems is to form a resist film with uniform thickness on a wafer. To form a resist film in a uniform thickness on the wafer, it is important to correctly control the temperature of heat treatment of the resist coated wafer.
In the case of chemically amplified resist, the pattern in the resist is amplified during a heat treatment step prior to develop. To achieve uniformity and consistency in this pattern, it is important to correctly control the temperature of (heat treatment of) the pre-develop wafer.
In general, a heat treatment apparatus for heating the wafer has a hot plate in which a heating element is disposed on the underside of a holding plate to hold the wafer. In such a heating apparatus, it would be desirable to detect the temperature of the holding plate surface (the treating position) to control the temperature of the holding plate. In most cases, since the temperature at the treating position can not be directly detected, a temperature sensor is buried in the holding plate, and the temperature at the treating position is estimated as being a fixed offset from the temperature detected by the buried temperature sensor. The heating value of the heating element disposed on the underside of the holding plate is controlled corresponding to the estimated temperature.
However, in the above heat treatment apparatus, there is a disadvantage that there exists a physical distance where material of the holding plate and a possible proximity air space lie between a position for treatment and a position where the temperature detector is buried, and a correct temperature control can not be performed because the actual offset between the treating position and the detector position is not fixed for the actual use condition.
For instance, a certain wafer is brought into the heat treatment apparatus immediately, but another wafer may be kept waiting for a long time just in front of the heat treatment apparatus before it is brought into the heat treatment apparatus. In such a case, each wafer has a different thermal load to the plate. Each different thermal load will produce a different offset between the treating position and the temperature detector position for some period of time. During this time, even though the temperature sensor buried in the holding plate detects the same temperature, the actual temperature on the surface of the holding plate is different. Also the high thermal load when the wafer is placed on the plate causes a large offset between the treating position and the detector position. This results in a low treatment temperature until the system stabilizes, giving a short time at the desired treatment temperature. Thus, when the time to treat a wafer at a desired treatment temperature is short, the film thickness of the resist is not stable and the resist film can not be formed in an uniform thickness on the wafer. The pre-develop bake is also less stable by the same mechanism, resulting in a less uniform pattern.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to provide a heat treatment apparatus and a heat treatment method to accurately estimate the temperature of the substrate treating position above the surface of the holding plate.
Another object of the present invention is to provide a heat treatment apparatus and a heat treatment method in which the substrate treating position can reach a desired temperature in a short time independent from the temperature history of the substrate and the time for treating the substrate at a desired temperature can be extended.
Still another object of the present invention is to provide a heat treatment apparatus and a heat treatment method in which a temperature sensor provided in the holding plate does not impact the heat treatment of the substrate.
To solve these disadvantages, the first aspect of the present invention is that an apparatus to carry out heat treatment to the substrate includes: a holding plate having a first face and a second face and holding the substrate on the first face; a heat energy supply section supplying heat energy from the second face side; a first temperature sensor disposed at a first position in a first depth from the first face of the holding plate detecting a first temperature of the first position; a second temperature sensor disposed at a second position in a second depth different from the first depth from the first face of the holding plate detecting a second temperature of the second position; and a control section controlling the heat energy to be supplied corresponding to a more accurate estimate of the treating position temperature calculated from the detected first and second temperatures.
The second aspect of the present invention is that an apparatus to carry out cooling treatment to the substrate includes: a holding plate having a first face and a second face and holding the substrate on or near the first face; a supply section supplying cooling energy from the second face side; a first temperature sensor disposed at a first position in a first depth from the first face, detecting a first temperature of the first position; a second temperature sensor disposed at a second position in a second depth from the first face, the second depth different from the first depth, the second temperature sensor detecting a second temperature of the second position; and a control section controlling the supplied cooling energy corresponding to a more accurate estimate of the treating position temperature calculated from the detected first and second temperatures.
The third aspect of the present invention is that an apparatus to carry out the heat treatment to the substrate includes: a holding plate having a first face and a second face, holding the substrate on or near the first face and having a hole of a predetermined depth in the second face toward the first face; a heat energy supply section supplying heat energy from the second face side; a first temperature sensor disposed at a first position in the hole to detect the first temperature at the first position; a second temperature sensor disposed at a second position which is different from the first position in the above described hole to detect the second temperature at the second position; and a control section to control the supplied heat energy corresponding to the detected first and second temperatures.
The fourth aspect of the present invention is that an apparatus to carry out a treatment to the substrate includes: a holding plate having a first face and a second face and holding the substrate on or near the first face; an energy supply section supplying the energy from the second face; means for detecting temperatures at positions each different in depth from the first face; and control means to control the energy to be supplied corresponding to the detected temperatures.
The fifth aspect of the present invention is that a method to supply heat energy from a back face of a holding plate and to heat-treat a substrate held on the surface of the holding plate includes: a step of detecting the first temperature at the first position in the first depth from the surface of the holding plate; a step of detecting the second temperature at the second position in the second depth which is different from the above described first depth from the surface of the holding plate; and a step of controlling the sup
Paschall Mark
Rader Fishman & Grauer
Tokyo Electron Ltd.
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