JPH05152402A - Size measuring method for resist pattern - Google Patents

Abstract

PURPOSE:To enhance the accuracy of a measured size by a method wherein a resist pattern is irradiated with a beam of excitation light by using an incident fluorescence system and the edge of the pattern is grasped clearly by means of a beam of emitted fluorescent light. CONSTITUTION:A resist pattern 2 with which a substrate 1 has been coated and which has been developed is irradiated, by means of an incident fluorescence system, with a beam of excitation light 3 which has extracted only a beam of light at a wavelength emitting beam of fluorescent light most efficiently by using an excitation filter from a light source such as a mercury lamp or the like. An image 4, by the beam of fluorescent light, including an inclined part at a width of 0.3mum or lower at the edge of the resist pattern 2 is measured. Thereby, the region of the resist pattern 2 can be grasped accurately, and the width of a fine stripe pattern can be measured without any error. As a result, the measuring time of the resist pattern can be shortened, an irregularity in the measured value of the resist pattern is reduced and the measuring accuracy of the resist pattern can be enhanced. The entitled method can contribute toward enhancing the quality of a semiconductor device which has been made fine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist pattern dimension measuring method. With the recent increase in integration and ultra-miniaturization of semiconductor devices, the dimensions of resist patterns drawn on semiconductor substrates are becoming smaller and smaller, and it is required to improve the dimensional measurement accuracy. Will be needed.

[0002]

2. Description of the Related Art FIG. 5 is an explanatory view of a conventional example. In the figure, 9 is a substrate, 10 is a resist pattern, and 11 is reflected light.

Conventionally, the dimension measurement of a resist pattern by white light has been usually performed by an epi-illumination microscope or the like.
The resist pattern 10 formed by applying and developing a resist film on the substrate 9 is semitransparent, and as shown in FIG.
Microscopically, the edge of the resist pattern 10 has a gentle slope and is very thin.Therefore, there is almost no reflected light 11, and the brightness of the reflected light 11 at the thick part of the resist pattern 10 is high. It was difficult to discriminate the edge area of the resist pattern, and it was difficult to accurately grasp the dimension and shape of the resist pattern.

[0004]

Under the above circumstances, it is difficult to clearly read and confirm the edge of the resist film by the conventional measuring method, and it is easy to cause an error in the dimension measurement, and the variation is large. Also, the measurement time was long.

In view of the above points, an object of the present invention is to develop a measuring method for accurately grasping the edge of a resist pattern.

[0006]

FIG. 1 is an optical path diagram of an epi-illumination type fluorescence microscope used in the present invention, and FIG. 2 is a principle diagram of a fluorescence microscope.

In the figure, 1 is a substrate, 2 is a resist pattern, 3 is excitation light, 4 is an image of fluorescence, 5 is an objective lens, 6
Is a dichroic mirror, 7 is an absorption filter, and 8 is a length measuring device.

In order to solve the above problems, the epifluorescence method is used to irradiate the resist pattern with excitation light,
The edge of the resist pattern is clearly grasped by the emitted fluorescence, and the measurement dimension accuracy is improved.

The reason is that since the photoresist film made of a photosensitive resin film is a synthetic resin film made of an organic substance, it emits fluorescence. In general, when an organic substance is irradiated with ultraviolet rays or light with a short wavelength, the organic substance absorbs the irradiation light and re-emits light longer than the wavelength of the absorbed light as fluorescence.

The images observed by the fluorescence microscope are all fluorescence due to organic substances including the resist and dusts on the wafer. Therefore, as shown in the principle diagram of the fluorescence microscope in FIG. 2, an excitation filter is used from a light source such as a mercury lamp to extract only the light of a wavelength that causes the fluorescent light to be emitted most efficiently, and the excitation light is a resist pattern that is an organic substance. To irradiate.

Then, since fluorescence is emitted from the resist pattern, only the fluorescence necessary for observation is extracted from the resist pattern using an absorption filter, and the resulting image is observed, or the dimension of the resist pattern is measured using a length measuring device. Take a measurement.

That is, as shown in FIG. 1, the object of the present invention is to irradiate a resist pattern 2 coated / developed on a substrate 1 with excitation light 3 by an epi-fluorescence method so as to emit fluorescence from the resist pattern 2. This is accomplished by measuring the dimensions of image 4.

[0013]

According to the present invention, the edge portion of the resist pattern can be clearly grasped by the epi-illumination of fluorescent light, the resist pattern and the surroundings can be clearly discriminated, and highly accurate dimension measurement can be performed. Can be measured.

[0014]

1 is an optical path diagram of an epi-illumination type fluorescence microscope used in the present invention, FIG. 3 is a wavelength characteristic of a dichroic mirror, and FIG. 4 is a measurement pattern of an embodiment of the present invention.

In the figure, 1 is a substrate, 2 is a resist pattern, 3 is excitation light, 4 is an image of fluorescence, 5 is an objective lens, 6
Is a dichroic mirror, 7 is an absorption filter, and 8 is a length measuring device.

An embodiment of the present invention will be described with reference to the drawings. Although fluorescence has various characteristics, one embodiment of the present invention was carried out using an epi-illumination fluorescence microscope that utilizes this characteristic.

As the characteristic of fluorescence, first, excitation light for emitting fluorescence from an organic substance such as a resist is required. Generally, the fluorescence wavelength is longer than the excitation wavelength. The energy of light becomes lower as the wavelength becomes longer, the energy of fluorescence becomes lower than that of absorbed light, and the intensity of fluorescence becomes extremely weak.

The fluorescence intensity F is proportional to the intensity I of the excitation light, the resist thickness D, and the fluorescence efficiency κ. For the F∝IDκ measurement, an epi-fluorescence microscope equipped with a dichroic mirror as shown in FIG. 1 was used. The dichroic mirror has wavelength characteristics as shown in FIG. 3, and reflects short wavelengths in the excitation light wavelength range but transmits only light in the fluorescence wavelength range.

Therefore, from the excitation light 3, only the light of the wavelength that causes the fluorescence to be most efficiently emitted is extracted and applied to the resist pattern 2. Then, from the fluorescence emitted from the resist pattern, only the fluorescence necessary for observation was extracted and formed into an image, and the size of this fluorescence image 4 was measured.

As a result, the edge of the resist pattern
By measuring the fluorescent image 4 including the sloped portion with a width of 0.3 μm or less, the region of the resist pattern can be accurately grasped, and the measurement of the pattern width of the fine stripe pattern can be performed without error.

[0021]

As described above, according to the present invention,
Since the edge part of the resist pattern can be clearly grasped by fluorescent epi-illumination and the dimension measurement can be performed with high precision, even a fine pattern can be accurately measured.

Therefore, the measurement time can be shortened,
Variations in measured values are reduced and measurement accuracy can be improved. Therefore, it greatly contributes to the quality improvement of the miniaturized semiconductor device.

[Brief description of drawings]

FIG. 1 is an optical path diagram of an epi-illumination fluorescence microscope used in the present invention.

[Fig. 2] Principle of fluorescence microscope

[Figure 3] Wavelength characteristics of dichroic mirror

FIG. 4 is a measurement pattern according to an embodiment of the present invention.

FIG. 5 is an explanatory diagram of a conventional example.

[Explanation of symbols]

 1 substrate 2 resist pattern 3 excitation light 4 fluorescence image 5 objective lens 6 dichroic mirror 7 absorption filter 8 length measuring instrument

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masataka Takemoto 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Inside Fujitsu Limited

Claims (1)

[Claims] 1. The size of the fluorescence image (4) emitted from the resist pattern (2) by irradiating the resist pattern (2) coated and developed on the substrate (1) with excitation light (3) by epi-illumination method. A method for measuring a resist pattern dimension, which comprises: