JP2845629B2 - Exposure method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure method, and more particularly to an exposure method suitable for removing unnecessary resist from a peripheral portion of a semiconductor wafer coated with a photosensitive resist.

2. Description of the Related Art Conventionally, in a process of forming a thin film laminated on a semiconductor wafer into a desired pattern in a semiconductor integrated circuit device manufacturing process, a resist film is applied on the thin film and passed through a mask formed in a desired pattern. After exposing the resist film, it is developed and etched to form a thin film in a pattern. In the resist coating step of coating a resist on a thin film, a spin coater is used to apply a resist solution by dripping a resist solution onto a semiconductor wafer and rotate the semiconductor wafer at a high speed. The resist film is applied to the portion. Therefore, when the peripheral portion of the semiconductor wafer is supported by the transport mechanism or the like, the excess resist film in the peripheral portion is peeled off, causing dust and particles to be generated. garbage,
In order to prevent generation of particles, there is a peripheral exposure apparatus that exposes only a peripheral portion of a semiconductor wafer to remove excess resist applied to the periphery and develops the semiconductor wafer (Japanese Patent Laid-Open No. Hei 1-1990).
187822, JP-A-1-194324, JP-A-1-194324
-217916, JP-A-1-251614, etc.).

The peripheral exposure apparatus uses a U.S.A. light source from a light source. The V light is guided by an optical conduit such as an optical fiber, the position of the semiconductor is detected by a position sensor, and the semiconductor wafer or the optical fiber is moved and rotated to expose the periphery of the semiconductor wafer. However, in these peripheral exposure apparatuses, the adhesive strength of the resist to the semiconductor wafer and the intensity of light for exposure are often not appropriate. In addition, polishing accuracy is poor at the edge of the semiconductor wafer, and dust and the like during transport of the semiconductor wafer are liable to adhere thereto, and the adhesion of the resist film is low. Also to gas vigorous generation of for example N ₂ or the like from the resist film when the light intensity is too strong for the exposure, resulting resist film resist debris scattered broken, attached to a lens or the like provided in the tip of the optical fiber Or the resist film was deformed, the irradiation distance was changed, and the irradiation intensity was uneven. In addition, the resist film may be further turned up and adversely affect the pattern formation portion.
The present invention has been made in order to solve the above-described drawbacks, and an exposure method for exposing a coating film applied to a peripheral portion of an object to be processed by exposing it with an appropriate intensity and forming a pattern with a high yield is provided. The purpose is to provide.

In order to achieve the above object, an exposure method according to the present invention moves a workpiece and light from a light source relatively to form a coating film applied to the workpiece. When exposing, when exposing the periphery of the object to be processed concentrically,
Exposure is performed by changing the intensity of irradiation light in a stepwise manner in the radial direction, and preferably, the irradiation intensity is reduced as the position is closer to the outer periphery.

When exposing the periphery of a semiconductor wafer coated with a resist to remove excess resist, the exposure intensity and time are adjusted according to the adhesion of the resist film to the semiconductor wafer. Therefore, the exposed area in the peripheral area is divided concentrically, and the part where the adhesion of the resist film near the center is strong is irradiated in a short time, and the area where the adhesion of the resist film near the edge is weak is irradiated for a long time. Irradiation enables exposure without adversely affecting the resist film in the pattern forming portion. In addition, since the exposure time can be shortened as a whole, a pattern can be formed with a good yield.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A peripheral exposure apparatus to which the exposure method of the present invention is applied will be described with reference to the drawings. Peripheral exposure apparatus 1 shown in FIG.
Is provided with a mounting table 3 that is connected to a vacuum pump or the like (not shown) and suction-fixes the semiconductor wafer 2 as a processing target. The mounting table 3 is connected to a rotation mechanism 4 such as a motor so that the semiconductor wafer 2 can be rotated. Further, the exposure apparatus 1
Is provided with a sensor 5 for detecting the position of the semiconductor wafer 2.
The sensor 5 includes a light projecting element 6, a lens 7 for converging light from the light projecting element 6, and a light receiving element 8 for receiving light passing through the lens 7, and a control unit for inputting an output from the light receiving element 8. 9, the periphery of the semiconductor wafer 2 can be detected, and the presence or absence of the semiconductor wafer 2 and the orientation flat portion 10 can be detected. The irradiation unit 11 that exposes the peripheral portion 21 of the semiconductor wafer 2 whose position is detected by such a sensor 5 includes a light source 1
2, a light conduit 13 such as an optical fiber for transmitting light from the light source 12 to the peripheral portion 21, a lens mechanism 14 for collecting light from the light conduit 13, and a diametrical direction (X direction) that supports the light conduit 13. A) a horizontal moving mechanism 15 such as a ball screw that can be moved to
A moving mechanism 16 for moving the horizontal moving mechanism 15 in a direction (Y direction) perpendicular to the moving direction of the horizontal moving mechanism 15; The irradiation unit 11 and the mounting table 3 are controlled by the control unit 9 based on information from the position sensor 5 of the semiconductor wafer 2. An exposure method using the peripheral exposure apparatus 1 having such a configuration will be described. A resist film 22 which is a coating film over the entire surface by a transport mechanism such as a handling arm (not shown).
The semiconductor wafer 2 coated with is mounted on the mounting table 3 while being positioned coaxially with the rotation axis of the mounting table 3. The semiconductor wafer 2 is fixed to the mounting table 3 by suction or the like. Then, the mounting table 3 is rotated by the rotation mechanism 4 to operate the position sensor 5. The light from the light emitting element 6 of the position sensor 5 is received by the light receiving element 8, and the control unit 9 measures the distance from the rotation center of the semiconductor wafer 2. The horizontal movement mechanism 15 is operated by the output signal from the control unit 9 to move the light conduit 13 and the lens mechanism 14 to the exposure position to expose the periphery 21 of the semiconductor wafer 2. At this time, a plurality of peripheral portions 21 of the semiconductor wafer 2 are concentrically arranged as shown in FIG.
1 and the outside 212, for example, the width of the peripheral portion 21 is 2
mm, each is divided into 1 mm, and the light from the optical conduit 13 is first radiated to the inside 211 of the semiconductor wafer 2 rotating at a high speed for 9 seconds at an illuminance of, for example, 1000 mW / cm ² . At this time, if the irradiation intensity is high, a gas such as N ₂ may be generated, but the adhesion strength between the semiconductor wafer 2 and the resist film 22 at the peripheral portion 21 of the semiconductor wafer 2 is such that
It has been confirmed that the intensity is higher than that of the 12 regions. In the case of this embodiment, the illuminance of the inside 211 is 1000 mW / cm.
^{When the} light is irradiated in step ² , the generated gas escapes into the atmosphere without damaging the resist film 22, and therefore, the resist film 22 breaks and stains the lens mechanism 14, or adheres to the resist film 22 as particles. It does not peel or peel off. Therefore, there is no possibility that the resist film in the pattern forming portion is peeled off or adversely affected. Next, the horizontal movement mechanism 15 is operated from the control unit 9 to set the position of the light conduit 13 to the outside 212. The outer side 212 has an illuminance relatively lower than the illuminance illuminating the inner side 211, for example, 300 mW / cm.
² for 30 seconds. Similar to the inner 211 at this time, although the gas such as N ₂ irradiation intensity stronger may occur, if also irradiated with illumination intensity and weaker than the inside in weak outside 212 of the adhesion strength than the inner 211 resist The film 22 is not peeled off, but is exposed while changing the illuminance inside and outside the peripheral portion 21. Irradiation can be strongly applied to the inside 211 of the resist film having strong adhesion strength in a short time, and irradiation can be performed for a long time by decreasing the illuminance of the outside 212 having low adhesion strength. By adjusting the irradiation intensity on the outside and inside in this way, it is possible to efficiently irradiate with an appropriate intensity, so that the light illuminance is not so strong that the resist film is not peeled off, and the conventional peripheral edge exposure method is used. 1 for exposure
It can be reduced to 2/3 where it was necessary for minutes.
The orientation flat 9 can be automatically operated by operating the moving mechanism 16 based on the detection from the position sensor in both the outer side 212 and the inner side 211 of the peripheral edge 21.
The semiconductor wafer 2 whose periphery has been exposed in this way is developed to remove the excess resist film at the peripheral edge, so that generation of dust and particles does not occur. In the above description,
Although the method of dividing the peripheral portion into two has been described, the exposure may be performed by further dividing the irradiation intensity according to the state of the adhesion strength of the resist film.

As is clear from the above description, according to the exposure method of the present invention, the exposure method according to the present invention can be used without affecting the resist film in the pattern forming portion according to the adhesion strength of the resist film in the peripheral portion of the semiconductor wafer. Since exposure is performed, high-quality pattern molding can be performed. Further, since the exposure time can be shortened, manufacturing with good yield can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment to which an exposure method according to the present invention is applied.

FIG. 2 is a view for explaining an exposure method according to the embodiment shown in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Peripheral exposure apparatus 2 ... Semiconductor wafer (object to be processed) 21 ... Peripheral part 22 ... Resist film (coating film)

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 21/027

Claims (2)

(57) [Claims] When exposing a coating film applied to a target object by relatively moving a target object and light from a light source, a peripheral portion of the target object is concentrically exposed. And an exposure method wherein the intensity of the light to be applied is changed stepwise in the radial direction. 2. The exposure method according to claim 1, wherein the irradiation intensity decreases as the outer edge of the peripheral portion increases.