# Patent

## Title
Semiconductor device manufacturing method

## Abstract

A semiconductor device manufacturing method of the present invention includes a coating step of coating a front surface of a wafer with a material containing a solvent, a volatilization step of volatilizing the solvent by heating the material, and a rinse step of jetting an edge rinse solution for removing the material from a first nozzle to a peripheral portion of the front surface of the wafer while rotating the wafer.

## Background
TECHNICAL FIELD
This invention relates to a semiconductor device manufacturing method used for manufacturing, for example, a large-scale integrated circuit (LSI).
BACKGROUND
Patent Literature 1 discloses dissolution and removal of a peripheral edge of a resist (material) formed on a front surface of a wafer.
PRIOR ART
Patent Literature
Patent Literature 1: Japanese Patent Laid-Open No. H8-264418
SUMMARY
Technical Problem
A material formed on a peripheral portion of a wafer may act as a contamination source in a subsequent step such as an exposure step or may attach to a wafer transport arm to cause the wafer to fall from the transport arm. It is, therefore, desirable to remove the material. However, even if the material on the peripheral portion of the wafer is removed by jetting a rinse solution to the material while the wafer is being rotated, the material formed on a central portion of the wafer spreads to the peripheral portion. Thus there is a problem that the material formed on the peripheral portion cannot be removed.
There is, in particular, a problem that when the viscosity of the material is high or when the volatility of a solvent contained in the material is low, the spread of the material to the peripheral portion by centrifugal force accompanying the rotation of the wafer is markedly large.
The present invention has been achieved to solve the above-described problem, and an object of the present invention is to provide a semiconductor device manufacturing method capable of unfailingly removing a material formed on a peripheral portion of a front surface of a wafer.
Means for Solving the Problems
A semiconductor device manufacturing method of the claimed invention includes a coating step of coating a front surface of a wafer with a material containing a solvent, a volatilization step of volatilizing the solvent by heating the material, and a rinse step of jetting an edge rinse solution for removing the material from a first nozzle to a peripheral portion of the front surface of the wafer while rotating the wafer.
Other features of the present invention will be made clear below.
Advantageous Effects of Invention
According to the present invention, the solvent in the resist is volatilized, so that the material formed on the peripheral portion of the front surface of the wafer can be unfailingly removed.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram explaining coating step.
FIG. 2 is a diagram explaining preliminary rinse step.
FIG. 3 is a diagram explaining volatilization step.
FIG. 4 is a diagram explaining rinse step.
FIG. 5 is a diagram showing the removal of the orientation flat adjacency material.
FIG. 6 is a diagram showing the removal of the orientation flat adjacency material.
FIG. 7 is a plan view of the wafer after the rinse step.



DESCRIPTION OF EMBODIMENTS
A semiconductor device manufacturing method according to an embodiment of the present invention will be described with reference to the drawings. Components identical or corresponding to each other are assigned the same reference characters, and repeated description of them is avoided in some cases.
Embodiments
First, as shown in FIG. 1, a wafer 12 is vacuum-attracted to a spin chuck 10. A coating of a material 14 is then applied to a front surface of the wafer 12. More specifically, to the wafer 12 rotated with the spin chuck 10, the material 14 is supplied from a nozzle 16 provided above the wafer 12. This step is called a coating step. The material 14 is a resist containing a solvent.
Subsequently, the process advances to a preliminary rinse step. FIG. 2 is a diagram for explaining the preliminary rinse step. In the preliminary rinse step, an edge rinse solution is jetted to a peripheral portion of the front surface of the wafer 12, and a back rinse solution to a back surface of the wafer 12, while the wafer 12 is being rotated with the rotation of the spin chuck 10.
More specifically, an edge rinse solution 22 for dissolving and removing the material 14 is jetted from a first nozzle 20 provided above the wafer 12. The edge rinse solution 22 is jetted to the peripheral portion of the front surface of the wafer 12. Also, a back rinse solution 26 for cleaning the back surface of the wafer 12 is jetted from a second nozzle 24 provided below the wafer 12. The back rinse solution 26 is jetted to the back surface of the wafer 12. Each of the edge rinse solution 22 and the back rinse solution 26 is an organic solvent such as γ-butyrolactone or NMP. The edge rinse solution 22 and the back rinse solution 26, however, are not particularly limited to this.
In the preliminary rinse step, the material 14 spreads concentrically outward with the rotation of the wafer 12. Therefore, the material 14 on the peripheral portion of the front surface of the wafer 12 cannot be completely removed. The reason that the material 14 spreads outward in the preliminary rinse step is that the solvent remains in the material 14.
Then the process advances to a volatilization step. FIG. 3 is a diagram for explaining the volatilization step. In the volatilization step, the wafer 12 is first transported onto a hot plate 30. The material 14 is heated (bake-dried) with the hot plate 30 to volatilize the solvent. A material 14A from which the solvent has volatilized has a thickness slightly smaller than that of the material 14 shown in FIG. 2.
Then the process advances to a rinse step. FIG. 4 is a diagram for explaining the rinse step. In the rinse step, the wafer 12 is first transported onto the spin chuck 10. The edge rinse solution 22 for removing the material 14A is jetted from the first nozzle 20 to the peripheral portion of the front surface of the wafer 12 while the wafer 12 is being rotated. At this time, since the solvent in the material 14A has already volatilized, the material 14A is dry and does not spread outward. Therefore, the portion of the material 14A formed on the peripheral portion of the front surface of the wafer 12 can be unfailingly removed.
In the rinse step, the back rinse solution 26 for cleaning the back surface of the wafer 12 is also jetted from the second nozzle 24 to the back surface of the wafer 12. The back surface of the wafer 12 can thus be cleaned.
Further, in the rinse step, a portion of the material 14A adjacent to the orientation flat as viewed in plan (hereinafter referred to as “orientation flat adjacency material 14a”) is removed. FIGS. 5 and 6 are diagrams showing removal of the orientation flat adjacency material 14a. As shown in FIG. 5, the position of the first nozzle 20 is adjusted so that the edge rinse solution 22 strikes the material applied to the peripheral portion of the wafer. Therefore, the edge rinse solution 22 does not strike the orientation flat adjacency material 14a. 
In the embodiment of the present invention, the second nozzle 24 is provided closer to a center of the wafer 12 (a center of the spin chuck 10) than the first nozzle 20, so that the back rinse solution 26 jetted from the second nozzle 24 strikes the back surface of the wafer 12 at all times while the wafer 12 is being rotated. The above-described orientation flat adjacency material 14a is removed by causing the back rinse solution 26 jetted from the second nozzle 24 to go around to the front surface of the wafer 12. FIG. 5 shows a state where the back rinse solution 26 goes around to the front surface side of the wafer 12 to remove part of the orientation flat adjacency material 14a. FIG. 6 shows a state where the orientation flat adjacency material 14a is removed with further progress in removal of the orientation flat adjacency material 14a from the state shown in FIG. 5.
Preferably, in order to cause the back rinse solution 26 jetted from the second nozzle 24 to go around to the front surface of the wafer 12, the back rinse solution is jetted at a flow rate of 100 to 150 ml/min from the second nozzle 24 while the wafer 12 is being rotated at 700 to 1000 rpm. If the rotational speed of the wafer 12 is lower than the range shown above, the amount of removal of the material 14A other than the orientation flat adjacency material 14a increases abruptly. On the other hand, if the rotational speed of the wafer 12 is higher than the range shown above, the back rinse solution 26 does not go around to the front surface of the wafer 12.
FIG. 7 is a plan view of the wafer 12 after the rinse step. Removal of the material on the peripheral portion of the front surface of the wafer 12 is completed. Removal of the orientation flat adjacency material is also completed. As a result, the outer portion of the wafer 12 is entirely exposed.
After the completion of the above-described steps, the wafer 12 is transported to an exposure apparatus and a well-known lithography process is performed on the wafer 12. Thus, the semiconductor device manufacturing method according to the embodiment of the present invention enables unfailingly removing the material formed on the peripheral portion of the front surface of the wafer 12.
The most important feature of the present invention resides in providing the volatilization step to prevent the material 14A from being spread outward by centrifugal force in the rinse step. Accordingly, the semiconductor device manufacturing method according to the embodiment of the present invention can be variously modified within such a scope as not to depart from this feature.
For example, the advantage of the present invention can also be obtained by performing the above-described steps on a wafer with a notch. In a case where there is no need to remove a portion of the material adjacent to the orientation flat or a notch as viewed in plan, it is not necessary to cause the back rinse solution 26 jetted from the second nozzle 24 to go around to the front surface of the wafer 12. In this case, the rotational speed of the wafer 12 in the rinse step and the flow rate of the back rinse solution 26 jetted from the second nozzle 24 are not limited to any particular values. Also, the second nozzle 24 itself may be removed.
The preliminary rinse step between the coating step and the volatilization step is not indispensable. The preliminary rinse step is provided for the purpose of preventing the material from attaching to a transport arm, preventing the wafer from attaching to the transport arm and preventing the wafer from falling from the transport arm during transport of the wafer 12 to the hot plate 30 after the coating step. If there is no possibility of the above-described detrimental effects, the preliminary rinse step is not indispensable. For example, transport of the wafer at the time of advancement from the coating step to the volatilization step can be eliminated by employing a spin chuck capable of heating and using the spin chuck as a hot plate.
In the volatilization step, the wafer 12 may be heated by certain means other than the hot plate 30. For example, the wafer 12 may be introduced into a heating furnace, and a heating wire for heating the wafer 12 may be provided in the chamber in which the coating step is performed. The material 14 is not limited to the resist. The material 14 may be polyimide for example. Therefore, the step after the completion of the rinse step is not limited to the exposure step.
DESCRIPTION OF SYMBOLS
10 spin chuck, 12 wafer, 14,14A material, 14a orientation flat adjacency material, 16 nozzle, 20 first nozzle, 22 edge rinse solution, 24 second nozzle, 26 back rinse solution, 30 hot plate

## Claims

1. A semiconductor device manufacturing method comprising:
a coating step of coating a front surface of a wafer with a material containing a solvent;
a volatilization step of volatilizing the solvent by heating the material; and
a rinse step of jetting an edge rinse solution for removing the material from a first nozzle to a peripheral portion of the front surface of the wafer while rotating the wafer, wherein
the wafer has an orientation flat or a notch,
in the rinse step, a back rinse solution for cleaning a back surface of the wafer is jetted from a second nozzle to the back surface of the wafer, and
in the rinse step, a portion of the material adjacent to the orientation flat or the notch as viewed in plan is removed by causing the back rinse solution jetted from the second nozzle to go around to the front surface of the wafer,
further comprising, between the coating step and the volatilization step, a preliminary rinse step of jetting the edge rinse solution to the peripheral portion of the front surface of the wafer and jetting the back rinse solution to the back surface of the wafer while rotating the wafer,
wherein the wafer is transported to a hot plate after the preliminary rinse step, and
the material is heated with the hot plate in the volatilization step.

2. The semiconductor device manufacturing method according to claim 1, wherein, in the rinse step, the back rinse solution is jetted at a flow rate of 100 to 150 ml/min from the second nozzle while the wafer is being rotated at 700 to 1000 rpm.

3. The semiconductor device manufacturing method according to claim 1, wherein the material is a resist or polyimide.