JPS60246632A - Method for reduced projection and exposure for photoelectronic image and system therefor - Google Patents

Abstract

PURPOSE:To maintain a photoelectronic image at a high-precision level by a method wherein the rear side of a reticle with a photoelectron emission pattern formed on its front side is cooled or heated and is kept at low or high temperatures as prescribed for the projection of a reduced image upon a substrate. CONSTITUTION:For the constitution of a means 20 to keep reticle temperatures constant, a cooling plate 22 is fixed to the rear of a reticle 4 by means of an adhesive 21 and a pipe 44 for such a coolant 27 as water or oil is fixed to the cooling plate 22 by means of welding. The coolant 27 is supplied via an inlet pipe 23 to a location at the middle of the reticle 4 to flow toward the flanks of the pipe 24, to finally leave the reticle 4 via outlet pipes 25, 26. The pipe 24 shaped U, W, etc., extends over the entire surface of the cooling plate 22 for uniform cooling. The cooling plate 22 is made of a Cu-based material noted for excellent thermal conductivity, and is fixed to the reticle 4 made of ordinary glass by the adhesive 21. The adhesive 21 should be a plastic-based agent, and if necessary, silver powder or the like is blended thereinto for improved conductivity.

Description

TECHNICAL FIELD The present invention relates to a method and apparatus for irradiating light onto a predetermined turn made of a photoelectron-emitting material and reducing and projecting the generated electron image onto a substrate via an electron optical system. .

Conventional exposure techniques using light have reached their limits in accuracy, and more accurate techniques using electron beams are becoming widespread. but,
Conventional electron beam exposure involves drawing a desired pattern with an electron beam, and therefore has the drawback of being time consuming.

Therefore, as shown in FIG. 1, the present inventors used the entire photoelectron generation reticle 4, irradiated the entire surface with uniform light Lt, and transferred the generated electron image to the base 1 on the stage 2. He has invented a method and apparatus for reducing projection through an optical system and is currently applying for a patent. The details of FIG. 1 will be explained later, so no further explanation will be given here.

Problems to be Solved However, with this method, several hundred W of light Lt-
Since the irradiation is performed in a vacuum, the reticle 4 is heated, its temperature increases, and the shape and dimensions of the reticle 4 change, which poses a problem. When the temperature of the reticle 4 changes, the dimensions of the exposed pattern change as a result.

Shape 1 position etc. will fluctuate. For example, glass (coefficient of thermal expansion 5x to'/℃) using t-100 mm (
If there is a temperature change of 1℃ in D diameter cvv-t-cle, 0.5
μ varies.

Considering that the reticle pattern is projected onto a substrate in a reduced size, this variation is 0.1 μm/°C in terms of shrinkage, which is 1 in shrinkage. It becomes 0.05 μm/u. In the future production of VLSIs, the limit for variations in patterns projected onto substrates is 0.1 μm, and preferably it should be much smaller than this. However, the temperature of the reticle increases by several tens of degrees Celsius, depending on the surrounding conditions, which poses a major obstacle to maintaining pattern accuracy.

OBJECTS OF THE INVENTION The present invention aims to solve all of the above problems by changing the temperature of the reticle. The purpose is to suppress bt and maintain high pattern accuracy of a photoelectron image reduced and projected onto a substrate.

Means for Solving Problems In the present invention, in order to achieve the above objects, the back surface of a reticle having a photoelectron emission pattern formed on the front surface is cooled or heated, and the temperature of the reticle is kept at a constant low temperature or a constant temperature, respectively. The reticle is maintained at a high temperature, and uniform light is irradiated from the front side of the reticle to generate a photoelectron image, which is reduced and projected onto the substrate via an electron optical system. On the back side of the reticle, either cooling or heating means is provided to maintain its temperature at a constant low or high temperature.

EXAMPLES Hereinafter, in order to specifically explain the present invention, examples will be shown and explained.

Embodiments of the Invention First, one embodiment of the photoelectronic image reduction projection exposure apparatus of the present invention will be explained in detail with reference to FIG. In the figure, 1 is a six semiconductor wafer (hereinafter simply referred to as a substrate) coated with an electron beam resist, and the substrate is fixed on a stage 2 equipped with a lateral (x-y) position and rotation adjustment mechanism (not shown). There is. A motor 3 is used to drive the stage 2. Note that the position of the stage 2 is read by a well-known means using a laser interferometer. A reticle 4 is arranged above the stage 2, and the reticle 4 has a curvature as shown in the figure to prevent the periphery of the image formed on the substrate from being eclipsed by tY. A pattern 7 made of a photoelectron emitting material is formed on the surface of the reticle 4, and the pattern is formed by forming and patterning a photoelectron emitting material J:, which does not produce photoelectrons. Then, around the pattern 7, alignment marks for photoelectron emitting material are formed. The figure shows two alignment marks 5.6. φ1 to φ4 are concentric electrodes that extract and accelerate generated photoelectrons, 8 is a blanking coil that finely adjusts the exposure time, 9 is an aperture that cuts off beams in undesired directions, and 1° is Polarizing coil for scanning; 11 is an axially symmetrical electromagnetic lens; 2 is a backscattered electron detector; 13, 14, 15 are ultraviolet lamps; 16,
17 and 18 are Nyasota. The light from the light sources 13 and 14 sequentially locally irradiates the marks 5 and 6, respectively, to generate a photoelectron beam 19 for positioning, and the beam 19 scans the entire mark (not shown) on the substrate 1. , obtain position information and perform alignment. Next, the pattern 7 of the reticle 4 is uniformly irradiated with light from the light source 15 to generate a photoelectronic image, and a photoelectronic image is compressed and projected onto the substrate through the electron optical system as described above. Normally, this reduction projection of the photoelectron 1↑ is repeated while feeding the chips one after another five times, and when the fog light of one substrate is finished, the substrate f loaded in a cassette (not shown) is
2 are set on the stage one after another (all exposures are performed with 2). Therefore, the reticle 4 is repeatedly irradiated with light from the light sources 13 to 15, so the temperature gradually increases. Means 20 for keeping the temperature of the reticle constant is arranged.The means 20 can be either cooling or heating means. It is forcibly cooled and kept at a constant low temperature (for example, room temperature).

On the other hand, the heating means is controlled so that the reticle temperature is maintained at a stable point on the high temperature side due to repeated irradiation K of strong light, that is, a point at which the temperature rise is saturated or a slightly higher temperature. Note that while the reticle is held at a constant temperature in this manner, the exposed electron beam resist of the semiconductor wafer that has been completely exposed is developed, and semiconductor devices are manufactured through the following process.

An embodiment of the means 20 for keeping the temperature of the reticle constant in the present invention will be shown below.

(Example 1) In Figure 3, a cooling plate 22 is fixed to the back of the reticle 4 with an adhesive 21, and a pipe 2 through which a cooling liquid 27t such as water or oil flows is attached.
4 are welded with a cooling plate 22 K 28. The cooling liquid is supplied from 23 near the center of the reticle, flows inside and outside through a pipe 24, and exits through 25 and 26. Vibrator 24 is U
It has an appropriate shape such as a letter or a W-shape and is placed over the entire surface of the cooling plate 22, and cools the cooling plate 22 uniformly. The cooling plate is a copper-based plate with good heat conductivity, and the reticle 4 (usually made of glass) is used.
and is bonded with adhesive 21. A plastic adhesive is used as the adhesive, and if necessary, a metal with good heat conductivity, such as fine silver powder, is mixed in.

Note that the water flow method is not limited to the one shown in Figure 2.
Any method may be used as long as cooling can be performed uniformly. The material of the reticle 4 is low expansion glass with an expansion coefficient of 5 x 10-'/'C or less.
Use quartz glass.

(Embodiment 2) In the bull's eye diagram, an elastic member 39 having good thermal conductivity is arranged between the reticle 4 and the cooling plates 30 to 32 to bring them into pressure contact. As the elastic member 39, for example, rubber with good thermal conductivity is used. With the interposition of the elastic member, the reticle 4 and the cooling plate □□□ come into surface contact and are uniformly cooled.

Note that unless an elastic member is used, the contact area between the metal cooling plate and the glass reticle is actually a small amount of the solder, and heat cannot escape. Note that also in this embodiment, the cooling plates 30 to 3
As in the previous embodiment, cooling water is flowed from vibrator 2 to vibrator A, 35 to a, and 37 to vibrator, respectively.

As mentioned above, in Examples 1 and 2, the temperature of the reticle 4 is set to a certain temperature by cooling, and therefore,
Thermal resistance is made as small as possible, and the flow rate of cooling water is made large so that the reticle temperature remains constant.

(Embodiment 3) In FIG. 5, a heating means (resistance heater, etc.) is arranged on the back surface of the reticle 4, and the temperature of the reticle 4 is measured by a sensor 4.
3, and the heating control device 44 adjusts the power supplied to the power supply #&45 based on the result.

This method actively raises the temperature of the reticle quickly and attempts to maintain it at a constant high temperature. In other words, if you wait for the reticle to reach a certain high temperature before starting exposure, it will take several tens of minutes to several hours to reach the certain high temperature (several tens of degrees Celsius to 100 degrees Celsius). In this embodiment, a heating means is added to promote the temperature rise of the reticle 4, and the temperature of the reticle 4 is set to the above-mentioned high temperature or a slightly higher temperature. This method can significantly shorten the waiting time after changing the reticle.

Although the present invention is widely applicable to microfabrication, it is extremely useful in manufacturing semiconductor devices (ultra LSI). In this embodiment, an alignment mark is formed on a semiconductor wafer such as silicon, an electron beam resist is applied, and the reticle temperature constant means of any one of Examples 1 to 3 is provided on the electron beam resist. The method is characterized in that a photoelectron image is reduced in size and projected, an electron beam resist is exposed, and after the exposure of the semiconductor wafer is completed, the electron beam resist is developed to form a solid pattern on the semiconductor wafer.

In addition to the effects of the invention, according to the present invention, it is possible to suppress fluctuations in the temperature of the reticle to within 1°C, it is possible to maintain high accuracy of the shield pattern on the reticle, and it is possible to apply electron beam resist. It becomes possible to carry out reduction projection exposure of photoelectronic images, which requires extremely high precision, such as exposure of semiconductor wafers, in a very stable manner over time.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the concept of a photoelectron image reduction projection exposure method, FIG. 2 is an overall schematic diagram showing the photoelectron image reduction projection exposure method and apparatus of the present invention, and FIG. FIG. 4 is a diagram showing the main parts of the second embodiment of the present invention. FIG. 5 is a diagram showing the main parts of the third embodiment of the present invention. figure. 1. Base & (semiconductor wafer), 2. Stage, 3.
・Motor, 4. Reticle, 7. Pattern (consisting of photoelectron emitting material), 9. Aperture, 11. Lens of axially symmetrical electromagnet, 12. Backscattered electron detector, 13.
゜14, 15...Ultraviolet lamp, 16, 17, 1
8. Shutter, 19... photoelectron beam for positioning, 20... means for keeping the temperature of the reticle constant,
21...Adhesive, 22...Cooling plate, 24...Bi7
．． 30, 31. 32...Cooling plate, 39. Elastic member. Patent Applicant Fujitsu Ltd. Representative Patent Attorney Hisa Gobe Tamamushi (1 other person) Figure 1 Figure 2 Figure 0 Figure 3 Figure 4 Figure 5

Claims (2)

[Claims] (1) Cool or heat the back side of a reticle on which the desired photoelectron emission pattern has been formed, and while keeping the temperature of the reticle constant, uniformly irradiate the photoelectron emission pattern with light from the front side. A photoelectronic image reduction projection exposure method characterized in that a preliminary photoelectronic image is generated, the photoelectronic image is completely reduced through an electron optical system, and the photoelectronic image is projected onto a substrate. (2) A reticle with a desired photoelectron emission pattern formed on its front side, cooling or heating means provided on the back side of the reticle to maintain the temperature of the reticle at a constant temperature, and a means for emitting photoelectrons from the front side of the reticle. A means for irradiating a pattern with uniform light, and an electron optical system for reducing and projecting an electron image generated by the irradiation of line light onto a substrate are all required! ! A photoelectronic image reduction projection exposure device having the following characteristics.