JPS60148115A - Reducingly projecting exposure device - Google Patents

Abstract

PURPOSE:To check fluctuation of resolving power of a reducingly projecting exposure device by a method wherein the intervals between a reducingly projecting lens, a semiconductor substrate and an exposure mask are corrected corresponding to the variation of the focal distance of the lens thereof. CONSTITUTION:An exposure device is constructed of an exposure mask 1, a semiconductor substrate 2, a projecting lens 3, an automatically focus detecting mechanism 5, a focal position setting mechanism 6, a piezoelectric device 9, etc. Light transmitted through the mask 1 is projected to the substrate 2 transmitting through the lens 3. At this time, light makes the temperature of the lens 3 itself to rise to change the focal position thereof. A computer 11 drives a lens barrel 4 and the device 9 according to the rate of opening and closing of a shutter, the measured value of an average illuminance measuring instrument 8 and feedback from the mechanism 8 to correct fluctuation of the focal distance.

Description

[Detailed description of the invention] The present invention relates to a reduction projection exposure apparatus.

In recent ultra-high-density semiconductor devices.

The minimum dimensions and reproducibility of element patterns required for device design have become extremely strict, and a light path device that can achieve this has become extremely strict.

Reduction projection type exposure apparatuses are becoming common.

In response to this, various plans are being developed and implemented for the reduction projection type exposure apparatus in the United States in order to improve throughput, which is considered to be a drawback in adapting to mass production. The main objective for the US is to increase the area that can be projected by lightning while maintaining or increasing the resolution by increasing the diameter of the projection lens system.
, ma'fc, = shortening of exposure time due to the same illuminance of the optical illumination system.

By the way, there is no prospect that the transmittance of the lens itself of a projection lens system will be dramatically improved in the future, and the transmittance is said to be around 90%.

Conversely, around 10% of the exposure energy is absorbed into the projection lens system, becomes heat, and remains a factor that deforms the lens itself. will become increasingly important for mass production use. The present invention addresses the above-mentioned problem, namely the variation in focal length caused by the thermal influence on the projection lens exerted by the exposure energy. By being able to automatically correct the focal position and magnification during exposure, it not only increases the yield rate of conductor integrated circuits, etc., but also increases the minimum size of semiconductor devices that can be produced. It is an object of the present invention to provide a reduction projection type exposure apparatus having a function of obtaining a total of 9 of the same practical performance as that of the above-mentioned strangles that can be miniaturized. In a reduction projection type exposure device that exposes and transfers a drawn image onto a semiconductor substrate coated with photoresist, the focal length of the projection lens is caused by the path light energy irradiated during exposure of the element pattern on the % exposure mask. This is a reduction projection type exposure apparatus that has a function of correcting the distances between the exposure mask and the projection lens and between the projection lens and the semiconductor substrate in response to fluctuations in the exposure mask and the projection lens and the semiconductor substrate to maintain magnification and resolution. When aligning and exposing the semiconductor substrate on which the entire photoresist has been applied, the exposure ultraviolet rays of the reduction projection lens are used to project and expose the element pattern (pattern of an integrated circuit, etc.) on the exposure mask onto the semiconductor substrate. By automatically controlling the distance between the reduction projection lens and the semiconductor substrate and the distance between the reduction projection lens and the exposure mask in response to changes in the economical focal length caused by heat absorption due to irradiation, 4. It is possible to always maintain the projection plate at the focal position of the projected image of the element pattern on the lightless mask and maintain the projection magnification, thereby making it possible to always obtain a good element pattern image, and using no equipment. This is a reduction projection type exposure device that can improve the practical performance of the device itself by increasing the quality of the semiconductor integrated circuits, etc. produced in the same manner as in production, as well as further miniaturizing the patterns of semiconductor integrated circuits, etc. that can be produced. .

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. Figure 1 is a detailed explanatory diagram of non-invention in Figure 6.
is an exposure mask, and 2 is a semiconductor substrate.

3 is a projection lens, 4 is a lens barrel, 5 is an automatic focus detection mechanism, 6
7 is a focal position setting mechanism, 7 is an X and Y moving stage, 8 is an average illumination meter, 9 is a piezo element, 10 is an exposure mask holding mechanism, 11 is a computer, and 12 is a terminal.

First, the heat shadow 4 produced on the projection lens by exposure energy irradiation will be explained. First, the light that has passed through the exposure mask 1 passes through the projection lens 3 and is irradiated onto the semiconductor substrate, but a part of this light is absorbed by the projection lens and increases the temperature of the projection lens itself. The temperature at which this equilibrium is reached is proportional to the exposure energy irradiated per unit time, and the rate of temperature rise (in hours) is partially due to the projection lens. In addition, the amount of change in the focal position and the amount of change in magnification are functions of temperature, and these are also experimentally determined by the projection lens. By managing the average illuminance per projected area of exposure light, the ratio of exposure light per unit time (time ratio of shutter open and shutter open), and the economic rate of change, the above function can be adjusted. Therefore, the amount of change in the focal point position and the JIS amount of change in magnification due to the influence of heat at that point can be estimated.

What is the procedure for the path light in this reduction projection double viewing device?

First, as in the normal case, the exposure mask 1 is set in the exposure mask holding mechanism 10, and the X and Y moving stage 7 is moved according to the instructions from the combination 11.

The average illuminance meter 8 is moved to the position where the pattern image of the exposure mask 1 is projected, and the average illuminance of the projected image is measured and output to the computer.Similarly to the case of construction of the semiconductor substrate 2
is supplied to the X and Y moving stages to start exposure, but the opening and closing of the shutter is recognized by the combination 11.

The ratio of opening and closing of the shutter per unit time and its changes are stored in the computer. Based on these calculations, the amount of change in the magnification is calculated from the function obtained through actual tests on the computer, and the corresponding change in the distance between the projection lens 3 and the exposure mask 1 is given using a piezo element 9, etc. , to compensate for this magnification change.

Similarly, the amount of change in the focal position is also calculated, the amount of change in the focal position caused by the magnification correction is added to this, and the result is output to the focal position setting mechanism 6. As a result, the lens barrel 4 is moved up and down by the feed pack from the automatic focus detection mechanism 5 to the installed focal position, thereby maintaining the entire distance between the newly installed projection lens 3 and the semiconductor substrate 2. By repeating the above in the same way.

It becomes possible to maintain the fif ratio of the projection and to always maintain the semiconductor substrate at a proper focal position when passing the light through the semiconductor substrate.

As described above, according to the present invention, the variation in magnification of the projected image caused by the absorption of path light energy in the projection lens, which is a huge problem in mass production, and the variation in resolution caused by the variation in the focal position wJt-corrected. 9, it is possible to substantially improve the yield rate of semiconductor devices produced using this apparatus, and also to further miniaturize the pattern metal of the semiconductor devices that can be produced. Furthermore, the present invention has made it possible to solve the most serious problem in implementing measures to improve throughput due to path light illuminance. Therefore,
The practical effects of non-invention are extremely large.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating the present invention in detail. In Figure 1, 1... Path light mask, 2...
Semiconductor substrate, 3... Projection lens, 4...
・Lens barrel, 5... Automatic focus detection mechanism, 6...
・・Lii setting mechanism with focus, 7 ・・・X, Y moving stage, 8 ・・・average illuminance meter, 9 ・・・
・Piezo element, 10... Exposure mask holding mechanism. 11...Computer, 12. Mountain...Terminal.

Claims (1)

[Claims] In a reduction projection type exposure apparatus that performs exposure by aligning an exposure mask and a semiconductor substrate coated with photoresist, a focus is created by heat absorption of a reduction projection lens that projects the element pattern on the non-light mask onto the semiconductor substrate. A patented reduction device comprising a BJ capable of automatically correcting the distance between the reduction projection lens and the semi-quadram substrate and the distance between the reduction projection lens and the exposure mask in response to changes in distance. Projection exposure equipment.