text: 1. Field of the Invention
  The present invention relates to a developing method for developing an exposure pattern after a resist film formed on a substrate such as a semiconductor wafer, an LCD substrate, or the like is exposed in accordance with a predetermined pattern.
  Moreover, the present invention relates to a substrate processing apparatus for applying a processing solution such as a developing solution, a cleaning solution, or the like on the front surface of a substrate to be processed such as a semiconductor wafer.
  2. Description of the Related Art
  In a coating and developing processing system for a photolithography process in processes of semiconductor device fabrication, for example, resist coating processing for forming a resist film on the front surface of a semiconductor wafer and developing processing for developing the semiconductor wafer after the resist-coated semiconductor wafer is subjected to exposure processing are performed.
  In the developing processing, the wafer which is exposed in accordance with a predetermined pattern and subjected to post-exposure bake processing and cooling processing is carried into a developing unit to be mounted on a spin chuck. A developing solution is supplied from a developing solution supply nozzle and applied (heaped up) so as to have a thickness of 1 mm, for example, on the entire surface of the semiconductor wafer, and thus a developing solution puddle is formed. The wafer remains stationary for a predetermined period of time with the developing solution puddle being formed, and developing processing progresses by natural convection. Thereafter, the developing solution is thrown out by the rotation of the semiconductor wafer by means of the spin chuck, and then a rinse solution is discharged from a rinse solution supply nozzle to rinse away the developing solution remaining on the wafer. Subsequently, the spin chuck is rotated at a high speed, whereby the developing solution and the rinse solution remaining on the semiconductor wafer are thrown out, and the wafer is dried. Thus, successive developing processing is completed, and a resist pattern film is formed.
  When the developing solution puddle is formed in this developing processing, nozzles of various shapes are used for applying the developing solution on the entire surface of the semiconductor wafer, and the wafer is rotated and the nozzle is scan-moved while the developing solution is being discharged from the nozzle.
  In the aforesaid conventional developing method, however, the time to heap up the developing solution, impact at the time of supply of the developing solution, displacement speed of the developing solution, and the like are uneven in the surface of the semiconductor wafer by any means when the developing solution puddle is formed on the semiconductor wafer, thereby making it difficult to obtain the uniformity of line width of the resist pattern film. Moreover, defects are prone to occur due to entry of bubbles in heaping up the solution and the like.
  Recently, with high integration of devices from 64 Mbits to 256 Mbits, it is increasingly demanded to scale down circuit patterns, and the minimum line width almost reaches a super-submicron region of not more than 0.2 xcexcm. In order to meet the demand, a chemically amplified resist is used as a resist capable of microfabrication, but the chemically amplified resist has poor wettability for the developing solution, so that the aforesaid defects are prone to occur. When microfabrication is performed with the chemically amplified resist, the ununiformity of line width due to the aforesaid unevenness becomes remarkable because the chemically amplified resist has extremely high sensitivity to the developing solution.
  An object of the present invention is to provide a substrate processing method and a substrate processing apparatus capable of uniformly performing predetermined processing with a solution on a substrate.
  Another object of the present invention is to provide a substrate processing method and a substrate processing apparatus in each of which line width can be made uniform in developing processing and defects do not tend to occur during the coating of the developing solution.
  To solve the aforesaid problems, the present invention is a substrate processing method for performing predetermined processing for a front surface of a substrate by at least one of a first solution and a second solution having a specific gravity smaller than the first solution, comprising the steps of: (a) supplying a mixed solution in which the first solution and the second solution are mixed onto the substrate; and (b) leaving the substrate to which the mixed solution is supplied as it is at least until the mixed solution is separated into the first solution and the second solution on the substrate.
  Moreover, the present invention is a substrate processing method for developing an exposure pattern after a resist film formed on a substrate is exposed in accordance with a predetermined pattern characterized by comprising the steps of: stirring a developing solution and a solution with a specific gravity smaller than the developing solution; and supplying the stirred developing solution and solution onto the exposed resist film on the substrate and leaving them as they are.
  According to such structures, in the developing processing, the mixed solution produced by stirring the developing solution and the solution with the specific gravity smaller than the developing solution is supplied to the front surface of the substrate, whereby immediately after the supply of the mixed solution, a chemical reaction between the developing solution and the resist hardly ever occurs, and developing does not progress practically. Then, the mixed solution is left as it is for a fixed period of time after being supplied onto the wafer W, and thereby the mixed solution is separated into two layers of which the lower layer is the developing solution and the upper layer is the solution. In this point of time, the developing solution is completely spread uniformly over the entire surface of the wafer W, and developing progresses under this situation. Thus, the developing progresses on the entire surface of the wafer W all at once. As a result, time difference in start time of developing does not occur in the surface of the wafer W, thereby enabling uniform developing and an improvement in line width uniformity (CD value uniformity) of a resist pattern film in the surface of the wafer W.
  A substrate processing apparatus of the present invention comprises: a holder for holding a substrate; and a nozzle for supplying a mixed solution in which a first solution and a second solution with a specific gravity smaller than the first solution are mixed onto the held substrate.
  Moreover, a substrate processing apparatus of the present invention is characterized by comprising: a mounting table on which a substrate on which an exposure pattern is formed after a resist film is exposed in accordance with a predetermined pattern is horizontally held with the exposure pattern facing upward; and a mixed solution storage vessel for stirring a developing solution and a solution having a specific gravity smaller than the developing solution which are to be supplied to the substrate and storing them.
  According to such apparatus of the present invention, in the developing processing, the mixed solution produced by stirring the developing solution and the solution with the specific gravity smaller than the developing solution is supplied to the front surface of the substrate. As a result, immediately after the supply of the mixed solution, a chemical reaction between the developing solution and the resist hardly ever occurs, and developing does not progress practically. Then, the mixed solution is left as it is for a fixed period of time after being supplied onto the wafer W, and thereby the mixed solution is separated into two layers of which the lower layer is the developing solution and the upper layer is the solution. In this point of time, the developing solution is completely spread uniformly over the entire surface of the wafer W, and developing progresses under this situation. Thus, the developing progresses on the entire surface of the wafer W all at once. As a result, time difference in start time of developing does not occur in the surface of the wafer W, thereby enabling uniform developing and an improvement in line width uniformity (CD value uniformity) of a resist pattern film in the surface of the wafer W.
  A substrate processing apparatus of the present invention according to another aspect comprises: a holder for holding a substrate; a first nozzle for supplying a first solution onto the held substrate; a second nozzle for supplying at least one of a second solution and a gas onto the held substrate; and a moving mechanism for moving a supply position of the first nozzle and moving the second nozzle so that the first solution which has been just supplied from the first nozzle is removed by at least one of the second solution and the gas supplied from the second nozzle.
  Moreover, a substrate processing apparatus of the present invention is characterized by comprising: a substrate holding mechanism for horizontally holding a substrate; a rotating mechanism for rotating the substrate in a horizontal plane; a processing solution supply nozzle moving along a direction, in which an outer edge portion and a central portion of the substrate are linked, to supply a processing solution onto the substrate while the substrate is being rotated by the rotating mechanism; and a rinse solution supply nozzle, disposed adjacent to the processing solution supply nozzle so as to be positioned in a spreading direction of the processing solution supplied onto the substrate, for supplying a rinse solution onto the substrate simultaneously with the supply of the processing solution.
  According to such structures of the present invention, the processing solution which has been just dropped from the processing solution supply nozzle is new and a region into which the processing solution has been dropped is processed by the new processing solution. This solution used for processing is spread by the rotation of the substrate, but this used solution which is spread is immediately removed by the rinse solution supplied from the rinse solution supply nozzle. Therefore, the new processing solution is always supplied to the entire surface of the substrate, and the processing solution with high processing capability is supplied onto the entire surface of the substrate. Consequently, unevenness of processing is eliminated in the entire surface of the substrate, resulting in efficient processing.
  A substrate processing apparatus of the present invention is characterized by comprising: a substrate holding mechanism for horizontally holding a substrate; a rotating mechanism for rotating the substrate in a horizontal plane; a processing solution supply nozzle moving along a direction, in which an outer edge portion and a central portion of the substrate are linked, to supply a processing solution onto the substrate while the substrate is being rotated by the rotating mechanism; and a rinse solution supply nozzle for supplying a rinse solution for removing the used processing solution after the processing solution supplied onto the substrate is used for processing onto the substrate simultaneously with the supply of the processing solution.
  According to such a structure of the present invention, the processing solution which has been just dropped from the processing solution supply nozzle is new and a region into which the processing solution has been dropped is processed by the new processing solution. Since this solution used for processing is immediately removed by the rinse solution, the new processing solution is always supplied to the entire surface of the substrate, and thus the processing solution with high processing capability is supplied onto the entire surface of the substrate. Consequently, unevenness of processing is eliminated in the entire surface of the substrate, resulting in efficient processing.
  A substrate processing method of the present invention comprises the steps of: moving a supply position while supplying a first solution onto a substrate; and supplying at least one of a second solution and a gas immediately after the supplied first solution so as to remove the supplied first solution.
  Furthermore, the present invention is a substrate processing method comprising the steps of: rotating a substrate which is horizontally held; and supplying a processing solution and a rinse solution from a processing solution supply nozzle and a rinse solution supply nozzle respectively to the substrate while moving the processing solution supply nozzle and the rinse solution supply nozzle along a direction in which an outer edge portion and a central portion of the substrate are linked, characterized in that the rinse solution supply nozzle is positioned in a direction in which the processing solution supplied onto the substrate spreads.
  According to such structures of the present invention, the processing solution which has been just dropped from the processing solution supply nozzle is new and a region into which the processing solution has been dropped is processed by the new processing solution. This solution used for processing is spread by the rotation of the substrate, but this used solution which is spread is immediately removed by the rinse solution supplied from the rinse solution supply nozzle. Therefore, the new processing solution is always supplied to the entire surface of the substrate, and the processing solution with high processing capability is supplied onto the entire surface of the substrate. Consequently, unevenness of processing is eliminated in the entire surface of the substrate, resulting in efficient processing.
  A substrate processing method of the present invention is characterized by comprising the steps of: rotating a substrate which is horizontally held; and supplying a processing solution and a rinse solution from a processing solution supply nozzle and a rinse solution supply nozzle respectively to the substrate while moving the processing solution supply nozzle and the rinse solution supply nozzle along a direction in which an outer edge portion and a central portion of the substrate are linked, wherein the rinse solution removes the used processing solution after the processing solution supplied onto the substrate is used.
  According to such a structure of the present invention, the processing solution which has been just dropped from the processing solution supply nozzle is new and a region into which the processing solution has been dropped is processed by the new processing solution. Since this solution used for processing is immediately removed by the rinse solution, the new processing solution is always supplied to the entire surface of the substrate, and thus the processing solution with high processing capability is supplied onto the entire surface of the substrate. Consequently, unevenness of processing is eliminated in the entire surface of the substrate, resulting in efficient processing.
  These objects and still other objects and advantages of the present invention will become apparent upon reading the following specification when taken in conjunction with the accompanying drawings.