JPH05335211A - Aligner for semiconductor manufacture - Google Patents

Abstract

PURPOSE:To achieve that a lens distortion and a magnification error as lens performances in an aligner for semiconductor manufacture are corrected automatically, in a short time, with high accuracy and ease. CONSTITUTION:The following are installed a reticle 11, for mesurement, or which vernier main scale is formed above a wafer stage 8 in order to measure the performance of a projection lens 10; and a light-sending part 6 which sends reference light used as the main scale on the wafer stage 8. A photo-detection part 1, a signal processing part 4 and a dislocation-amount operation part 5 are installed at the illumination part in an aligner. Thereby, a lens distorion and a magnification error as lens performances are measured by processing an image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor manufacturing exposure apparatus, and more particularly to a semiconductor manufacturing exposure apparatus having a function of automatically measuring a lens distortion and automatically correcting a magnification error.

[0002]

2. Description of the Related Art In the conventional exposure value for semiconductor manufacturing,
When measuring the lens distortion and magnification error, which are the optical performances of the projection lens, exposure was performed using a dedicated reticle and a resist-coated wafer as shown in the flowchart of FIG. This is because the vernier main scale is first exposed over the entire exposure range at an arbitrary interval, then the main scale is masked, and the vernier sub-scale on the reticle is second exposed at an arbitrary interval by feeding the wafer stage. The double exposure method was performed, the wafer was developed, and the deviation amount of vernier was read by an optical microscope.

[0003]

In this conventional exposure apparatus for semiconductor production, the main scale and the subscale are double-exposed on the resist-coated wafer at arbitrary intervals depending on the feeding accuracy of the wafer stage, and after development, Since humans read the vernier with an optical microscope to obtain the lens distortion and magnification error, the measured values include variations in the wafer stage feed accuracy and human variability in reading the vernier. There was a problem of low sex.

Further, in recent years, the device standard for lens distortion and magnification error has become 3/100 to 5/100 microns, which is at the same level as the dispersion of these measurement accuracy, and it is necessary to improve the accuracy of the actual measurement value. .

[0005]

SUMMARY OF THE INVENTION An exposure apparatus for semiconductor manufacturing according to the present invention includes a measuring reticle having a vernier scale mark for performing measurement, and a slit light beam arranged in a reference grid serving as a main scale mark. An optical system is provided on the wafer stage, and an optical system consisting of a half mirror that optically detects the displacement between the main scale and the vernier scale, a condenser lens, and a light receiving unit, a signal processing unit that performs image processing of the received light signal, and a position. A deviation amount calculator and a magnification error calculator are provided.

[0006]

Next, the measurement principle of the exposure apparatus of the present invention will be described with reference to the drawings. FIG. 3 is a plan view of a measurement reticle provided with a BOX mark (measurement mark) as a vernier scale, and FIG. 4 is a partially enlarged view thereof. FIG. 5 is a plan view of a light transmitting unit that irradiates BOX mark-shaped light, which is the main scale,
FIG. 6 is a partially enlarged view thereof. The measurement reticle and the light transmitting unit can be relatively aligned with each other by the reticle set mark of the measurement reticle reduced and projected and the reticle alignment reference mark provided on the light transmitting unit. If the light is emitted from the light transmitting section in a state where the center coincides with the center of the light transmitting section, the light receiving section can detect an optical signal as shown in the measurement principle explanatory diagram of FIG. 7, and ΔL = ( The positional deviation can be calculated by (L1-L2) / 2.

FIG. 8 is a waveform diagram showing a change in a light receiving signal when the wafer stage is moved in the vertical direction. As shown in the figure, when the reticle and the light-transmitting unit on the stage are in focus, the signal intensity H is highest and the contrast B is highest. Therefore, it is possible to automatically perform focusing at the time of measurement.

[0008]

The present invention will be described below with reference to the drawings. 1 is a configuration diagram of a first embodiment of the present invention. In addition, among the mechanical parts of the present embodiment, the wafer holder 9, the main condenser lens 12, the reflection mirror 13, and the relay lens 1
4, 15, a reflection mirror 16, an elliptical mirror 17, an optical unit 18,
The mercury lamp 19 and the like have the same structure as the conventional device.

First, the measurement reticle 11 is positioned in the exposure apparatus, the wafer stage 8 is moved so that the center of the measurement reticle 11 and the center of the light transmitting section 6 are aligned, and after the wafer stage 8 is stopped, the light transmission is performed. By irradiating the illumination light from the section 6, the light of the light-sending points (slits) arranged in the reference grid pattern provided on the light-sending section 6 on the wafer stage 8 passes through the projection lens 10 and the measurement reticle 11. Then, the half mirror 3 reaches the light receiving section 1 through the condenser lens 2. Here, the signal processing unit 4 performs image processing, and the position shift calculation unit 5 calculates the amount of position shift in the X and Y directions at each reference grid point based on the coordinate data of the wafer stage control unit 7. This value becomes the lens distortion and magnification error.

FIG. 2 is a partial configuration diagram of the second embodiment. The mechanical part is the same as that of the first embodiment. The conventional exposure apparatus for manufacturing a semiconductor includes a lens control unit 21 that calculates the amount of ultraviolet rays applied to the projection lens and automatically controls a change in magnification of the projection lens due to ultraviolet energy. Therefore, using the values of the lens distortion and the magnification error measured according to the first embodiment of the present invention, the correction amount is calculated by the lens magnification error calculation unit 20, and the lens control unit 21 is automatically controlled to perform the correction.

[0011]

As described above, according to the present invention, the error of the projection lens with respect to the reference grating provided in the light sending unit is adjusted by the reticle dedicated to measuring the lens distortion and the magnification error and the light sending unit provided on the wafer stage. Since it is detected by the light receiving portion, there is an effect that the lens distortion and the magnification error can be measured in a short time with high accuracy at the image processing level without exposing and developing the vernier pattern on the wafer.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a second embodiment of the present invention.

FIG. 3 is a plan view of a measurement reticle used in the present invention.

FIG. 4 is a partially enlarged view of FIG.

FIG. 5 is a plan view of a light transmitting section used in the present invention.

6 is a partially enlarged view of FIG.

FIG. 7 is an explanatory diagram of a measurement principle in the present invention.

FIG. 8 is a waveform diagram of a signal change in the present invention.

FIG. 9 is a flow chart showing lens distortion measurement of a conventional exposure apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light receiving part 2 Condensing lens 3 Half mirror 4 Signal processing part 5 Position shift amount calculating part 6 Light transmitting part 7 Wafer stage control part 8 Wafer stage 9 Wafer holder 10 Projection lens 11 Measurement reticle 12 Main condenser lens 13 Reflection mirror 14 , 15 Relay lens 16 Reflective mirror 17 Elliptical mirror 18 Optical section 19 Mercury lamp 20 Lens magnification error calculation section 21 Lens control section

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location H01L 21/66 Z 7352-4M

Claims (2)

[Claims] 1. A light transmitting section provided on a wafer stage for irradiating reference slit light, a reticle provided with a reference mark for measurement, a light receiving section for receiving light transmitted through the reticle, and An exposure apparatus for semiconductor manufacturing, comprising: a signal processing unit that processes a signal; and a positional deviation amount calculation unit that calculates a positional deviation amount based on the coordinate data of the wafer stage control unit and the data of the signal processing unit. 2. A lens magnification error calculation unit for calculating a correction amount of a magnification error based on a value measured by the position shift amount calculation unit, and a lens control unit is controlled by a signal from this calculation unit. 1. The exposure apparatus for semiconductor manufacturing according to 1.