1. Field of the Invention
The present invention relates to a technique for performing predetermined substrate processing such as hydrophobic processing on a semiconductor device, a LCD (liquid crystal display) substrate, etc.
2. Description of the Related Art
As one of a series of steps for forming a resist pattern in a manufacturing process for a semiconductor device, a LCD substrate, etc., hydrophobic processing is performed on a substrate such as a semiconductor wafer (hereinafter referred to as a “wafer”) W. This processing is performed to enhance the adhesion between a substrate film and a resist film before a resist liquid is applied thin film thereon so that the front surface property of the wafer W is changed from hydrophilicity to hydrophobicity. In this case, the hydrophobic processing is preferably performed on the front surface of the wafer W and a beveled part (the end surface of an outer peripheral part). The advantage of the hydrophobic processing is that the resist film is not easily peeled even when liquid immersion exposure processing is performed at a later process to expose light with water interposed between the wafer W and an exposure device.
Referring here to FIGS. 1 and 2, a description is made of the hydrophobic processing together with the configuration of an apparatus that performs this processing. First, the wafer W is conveyed into a processing chamber 10 composed of a container main body 11 and a cover body 12 and then mounted on a mounting board 13 (step S11). In other words, the wafer W is conveyed into an opening part formed when the cover body 12 is lifted up relative to the container main body 11, and then the cover body 12 is lowered to make the container main body 11 and the cover body 12 come into contact with each other so as to close the opening part. In this case, if the wafer W is transferred from an outer conveying unit to the mounting board 13, lifting pins 14 incorporated in the mounting board 13 are used.
Next, the processing chamber 10 is hermetically sealed (step S12). Because the emission of HMDS gas into a clean room causes particles or the HMDS reacts with the moisture in the air to cause ammonia that adversely affects the shape of a resist pattern, the processing chamber 10 is hermetically sealed to prevent the leakage of the HMDS gas. Specifically, in order to hermetically seal the processing chamber 10, an exhaust passage 15 formed at a contact part between the container main body 11 and the cover body 12 is exhausted by an exhaust unit 16 for hermetic sealing so that the container main body 11 and the cover body 12 are closely attached to each other by suction. In FIG. 1, reference numeral 15a denotes a seal member provided around the exhaust passage 15.
Subsequently, HMDS gas is supplied into the processing chamber 10 to perform the hydrophobic processing (step S13). At nearly the central part of the cover body 12, a gas nozzle 17 is formed. The FINDS gas is supplied into the processing chamber 10 in spray form from the gas nozzle 17 via a gas supply pipe 17b and a gas supply passage 17a formed in the cover body 12. The FINDS gas fills the processing chamber 10 in this manner so as to perform the hydrophobic processing. In this case, however, the HMDS gas is dispersed into a gap formed between the container main body 11 and the side wall part of the mounting board 13, movement areas of the lifting pins 14 formed in the mounting board 13, and an enclosure 14a covering the lifting areas of the lifting pins 14 formed below the mounting board 13. Then, the HMDS gas is extruded from exhaust passages 18 connected to the gap and the enclosure 14a and exhausted to outside of the processing chamber 10. Note that the exhaust unit 19 connected to the exhaust passages 18 is not actuated in this process.
After the completion of the hydrophobic processing, the HMDS gas is substituted for before the cover body 12 is opened (step S14). The purpose of the substitution processing is to prevent the emission of the HMDS gas from the processing chamber 10. In this process, N2 (nitrogen) gas as substitution gas is supplied to the gas supply pipe 17b, while the exhaust unit 19 is actuated. In this case, because the amount exhausted by the exhaust unit 19 is made slightly greater than the supplied amount of the N2 so as to prevent the emission of the HMDS gas from the processing chamber 10 in addition to the fact that the processing chamber 10 is hermetically sealed, the pressure inside the processing chamber 10 becomes negative. Following the substitution processing, the exhaust unit 19 is stopped to restore the pressure inside the processing chamber 10 to atmospheric pressure, while the exhaust unit 16 for hermetic sealing is stopped to open the processing chamber 10 (step S15). Then, the cover body 12 is lifted up to open the processing chamber 10, and the wafer W is taken out from the processing chamber 10 (step S16).
In such a hydrophobic processing apparatus, because the processing chamber 10 is hermetically sealed as described above, the pressures inside the movement areas of the lifting pins 14 and the enclosure 14a as well as the pressure inside the processing chamber 10 become negative during the substitution processing. As a result, the HMDS gas spreads to the rear surface of the wafer W, which causes the hydrophobic processing to be performed even on an unnecessary part of the rear surface of the wafer W. The allowable range of the hydrophobic processing on the rear surface of the wafer W is about 1 cm away from its outer peripheral part. However, if the FINDS gas largely spreads to the rear surface of the wafer W and the hydrophobic processing is performed thereon, the following problem arises. In other words, when paint thinner is supplied to cleanse the rear surface of the wafer W so as to remove a stain therefrom after the application of a resist liquid, the paint thinner is likely to be repelled to allow the stain to remain on the rear surface of the wafer W.
Furthermore, in order to hermetically seal the processing chamber 10, it is necessary to provide a hermetically-sealing mechanism including the exhaust passage 15, the seal member 15a, the exhaust unit 16 for hermetic sealing, etc., between the container main body 11 and the cover body 12. This results in an increase in the number of components of the hydrophobic processing apparatus and makes its structure complicated. Therefore, the assembling operation of the apparatus is a lot of trouble. In addition, the complicated structure easily causes an error in assembling the apparatus, which requires an operation for adjusting the error and an inspection process and a management process to determine the presence or absence of error in assembling the apparatus. As a result, this increases the burden on an operator.
Moreover, the gas nozzle 17 is formed tapered to supply the HMDS gas or the N2 gas in the processing chamber 10, and the HMDS gas or the like is sprayed downward toward the wafer W in spray form from the gas nozzle 17. Under this configuration, however, the degree of intensity in blowing the gas is different depending on an area, which easily causes air turbulence and generates a turbulent flow between the wafer W and the cover body 12. This results in hindering the quick dispersion of the gas. Therefore, the substitution of the HMDS gas for the N2 gas hardly advances, and thus the substitution processing takes much time.
Accordingly, the present inventors have studied a configuration for preventing the leakage of gas from the processing chamber without hermetically sealing the processing chamber. Meanwhile, Patent Document 1 proposes a configuration in which an upper constituent member and a lower constituent member are joined together without a clamp to maintain the air tightness of the processing chamber. Besides, Patent Document 2 proposes a technique for supplying processing gas and substitution gas into the processing chamber via different passages. However, these techniques are not intended to perform the hydrophobic processing without hermetically sealing the processing chamber and thus do not solve the above problems.    Patent Document 1: JP-A-11-214292    Patent Document 2: JP-A-10-135125