JPH03156914A - Apparatus and method for exposure of graphic - Google Patents

Abstract

PURPOSE:To eliminate instability of a chemical-amplification resist material and to enhance stability and reproducibility by a method wherein an exposed and treated resist specimen is held in a dry atmosphere until it is baked. CONSTITUTION:Individual wafers 3 are generally housed inside a jig 2 or the like in the air until the required number of wafers (one batch) are all exposed and treated by using an aligner; during this time, a vapor contained in the air acts on a catalyst existing inside a resist and causes a change with the passage of time. When a desired graphic is formed on a substrate on which a radiation-sensitive material has been applied, the substrate which is being exposed or has been exposed is held in a dry atmosphere 15. Consequently, it is possible to avoid a change in a pattern size between wafers which is caused by a phenomenon of changes of the catalyst with the passage of timer which are peculiar to a chemical-amplification resist material whose sensitivity, resolution and dry-etching resistant property are high. Thereby, it is possible to powerfully promote a manufacturing operation of a semiconductor element and an ultrafine device such as a ULSI or the like which will be integrated more and more highly in the future.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to lithography technology in ULST manufacturing, and more particularly to a pattern exposure apparatus and method for realizing a lithography process using a chemically amplified resist with high controllability and stability.

[Conventional technology 1] High integration and high density of ULSr are progressing at a rate of four times in three years, and mass production of 4 megabit dRAM and prototype production of 16 megabit dRAM have already been carried out. Along with this, the dimensions required for microfabrication range from 0.8 μm to 0.8 μm.
It is becoming increasingly finer, from 5 μm to 0°5 μm or less. Lithography technology plays a role in driving this miniaturization of devices. In lithography technology, energy beams such as light, Xa, and electron beams are used, and a resist material, which is a photosensitive material, is selectively irradiated with these energy beams to form a latent image in the resist. After this, by developing these latent images into real images, the base material is added.
Normally, a resist mask is formed. Therefore, the resist material used for this is required to have properties such as (1) high resolution, (2) high sensitivity, and (2) high processing resistance. However, there is no conventional resist material that simultaneously satisfies these three elements at a high level, and resist materials must be selected depending on the application, at the expense of one or the other. However, recently, for example, Journal of Vacuum 1
1 Science and Technology (J, Va.
c, Scj, Technol, ) 86(1),
Jan/Feb '88pp319-322. A chemically amplified resist utilizing a catalytic sensitization reaction was devised as shown in the same issue of the same magazine, pp. 379-383. This is a resist material with a new mechanism in which an intermediate substance that serves as a catalyst is generated by irradiation with energy rays, and the resist reaction is efficiently promoted through subsequent heat treatment. As a result, high sensitivity can be achieved while maintaining the high resolution and high processing resistance of conventional resists. This is an ideal material for beams. Furthermore, such chemically amplified resists are positioned as mainstream resist materials in the future as well. 1 invention is I'l'? Problem to be solved] However, -1
- When chemically amplified cyst materials are used in manufacturing processes such as ULS■, variations in feature dimensions (thinness) occur among a large number of wafers, making it impossible to realize a stable and highly controllable link roughy process. It has been found. Figure 2 below (a
) will explain the L phenomenon in detail. Generally, wafer #2 is transferred to cassette 1 which stores n wafers.
] is transported to the figure exposure section 15. Next, a predetermined pattern is exposed to light on the resist coated on wafer #1. Thereafter, wafer #1 is transferred and stored in cassette 2 again. Next, wafer #2 is selected and subjected to a series of processes in the same manner as wafer #1. By repeating this process and completing all the processes up to wafer #n, the exposure process for one batch is completed. Thereafter, resist patterns are formed on these wafers #1 to #n through post-exposure baking and development processing as shown in the process flow of FIG. 2(b). However, in this sequence, wafer #1 and wafer #
A significant pattern dimension change occurred between the two. FIG. 3 shows the amount of deviation from the dimension design value of the fine pattern exposed on each wafer. As shown in the figure, we found that there were large differences in pattern dimensions between wafers. This is related to the fact that a typical electron beam exposure apparatus holds the exposed wafer in the atmosphere, and a typical stepper etc. performs exposure and holds the exposed wafer in the atmosphere. This means that the time from exposure to baking will necessarily differ for wafers #1 to #n.
As a result of exposure 1, the catalyst generated in the resist changes over time due to the difference in the length of time it is exposed to the atmosphere. Chemically amplified resists are ideal resists that can simultaneously achieve extremely high performance in terms of sensitivity and resolution, but ULS resists require stability and reproducibility due to the above phenomenon.
A problem arose in that it could not be applied to the I manufacturing process. Based on the above phenomenon, the present invention eliminates the instability of the chemically amplified resist material and provides ULSI with high stability and reproducibility.
The purpose is to introduce it into the manufacturing process.

[Means to solve the problem]

The above object is achieved by maintaining the exposed resist sample in a dry atmosphere until it is baked.

[Effect]

Generally, in an exposure apparatus, each wafer is stored in a jig or the like in the atmosphere until a predetermined number of wafers (one batch) have all been exposed. The authors discovered that during this time, water vapor contained in the atmosphere acts on the catalyst present in the resist, inducing changes over time. FIG. 4 shows the change over time of the resist from exposure to baking in air, vacuum, water vapor, and nitrogen. Changes over time were evaluated based on the dimensions of the fine patterns. This clearly shows that water is the cause of the change over time. Therefore, as shown in FIG. 1(8), a sample holding chamber 4 which can be replaced with any dry gas or can be evacuated as shown in FIG. 1(b) is provided in the exposure apparatus W1. By holding each wafer immediately after exposure in the holding chamber, it is possible to stop the change over time of the catalyst in the resist of each wafer caused by the water. As a result, it is possible to eliminate pattern dimension variations between wafers and realize a process using a chemically amplified resist with high stability and reproducibility. Here, some exposure devices perform exposure while replacing the atmosphere with nitrogen or the like, but this is intended to increase the sensitivity of the resist during exposure, and the stability and stability of resist characteristics. This is completely different from the present invention, which aims at controllability.

【Example】

Hereinafter, the present invention will be explained in more detail using Examples. <Example 1> Example 1 is a case in which an electron beam exposure apparatus is provided with a sample holding chamber 4 that can be replaced with dry nitrogen. FIG. 5 shows an outline of the electron beam exposure apparatus. The electron beam exposure apparatus is a variable shaped beam type exposure apparatus with an accelerating voltage of 30 kV. For the exposure sample, a negative chemically amplified resist material S A L601-ER7 (Shipley Microelectronics Co., Ltd.) was coated with a film thickness of 0.5 μm on a 4-inch SJ substrate. A 10-piece goldstone sample with a fixed exposure rate is placed in a sample waiting room 12 shown in FIG. 5, and transported one by one to an exchange room 14. After the exchange chamber 14 is brought to a high vacuum state of ~1 μT orr or less, which is comparable to that of the exposure chamber 11, it is transported to the exposure stage 5.
A predetermined fine pattern was exposed with a radiation dose of 8/LC/c, m'' to form a latent image.The exposed first sample was transported and stored in the holding chamber 4. Dry nitrogen gas with a relative humidity of approximately 5% was constantly flowed into the holding chamber 4 at a rate of 1.5 Q/min to maintain the same atmosphere.The second and subsequent sheets were processed in the same manner as the first sheet. After completing the processing of the 10-piece goldstone sample with a fixed exposure rate, all the samples were taken out from the sample holding chamber 4 and heated at 110°C for 20 minutes using a hot plate baking device.
A baking process was performed for a minute. Next, a pattern was formed by developing with developer MF 312 (Shipley Microelectronics). When the dimensions of this resist pattern were evaluated using a length-measuring scanning electron microscope 86000 (Hitachi), a good value of 0.02 μm/10 wafers in dimensional variation between wafers was obtained. <Example 2> In Example 2, dry oxygen gas with a relative humidity of approximately 5% was flowed into the holding chamber of Example 1. In this example as well, the same results as in Example 1 were able to be obtained. <Example 3> In Example 3, an electron beam exposure apparatus was provided with a sample holding chamber that could be evacuated to a vacuum. By setting the degree of vacuum to 10 μTorr or less, the same improvement effect in suppressing changes in resist properties over time as in Example 1 was observed in this case as well. <Example 4> In Example 4, an optical exposure apparatus using KrF excimer laser light with a wavelength of 248 nm was provided with a sample holding chamber that could be replaced with dry air. The flow rate of dry air with a relative humidity of approximately 5% is 1. ．． When the sample was held after heavy exposure at 5Q/min, the same improvement effect as in Example 1 was observed in this case as well. <Example 5> In Example 5, an optical exposure apparatus using K r F excimer laser light with a wavelength of 248 nm was provided with a sample holding chamber capable of cooling the atmosphere. The atmospheric temperature of the holding chamber is -15
C. and the relative humidity was 10% or less, the same improvement effect as in Example 1 was observed. [Effects of the Invention] According to the present invention, it is possible to avoid wafer-to-wafer pattern size variations caused by the aging phenomenon of a catalyst inherent in a chemically amplified resist material having high sensitivity, high resolution, and high dry etching resistance. Can be done. Therefore, the manufacturing of semiconductor elements such as ULSI and ultrafine devices, which will become increasingly highly integrated, will be strongly promoted in the future.

[Brief explanation of the drawing]

Figure 1(a) is a diagram illustrating a case where a sample holding chamber that can be replaced with any dry gas is provided to hold the sample after exposure in the exposed peripheral area, and Figure 1(b) is a diagram illustrating a case in which a sample holding chamber is provided in the exposed peripheral area to hold the sample after exposure. A diagram explaining a case where a sample holding chamber that can be evacuated to vacuum is provided to hold the sample after exposure. Figure 2 (a) shows a typical exposure apparatus consisting of an exposure section and a special sample section. Figure, 2nd
Figure (b) is a diagram showing the resist process flow when a normal exposure device is used, Figure 3 is a diagram showing the amount of deviation from the dimension design value of the fine pattern exposed on each wafer, and Figure 42
・Cassette, 3. Sample (wafer), 4. Sample holding chamber, 5. Stage, 6. Light source, 7. Pressure reducing valve, 8. Valve, 9. Vacuum pump, 10. ··gauge,
11... Electron beam exposure section, 12... Sample special equipment section, 13
. . electron gun, 14 . . . sample exchange chamber, 15 . . . sample holding chamber that allows the figure exposure section to be opened. Explanation of symbols No. 2 0(b) Fig. 4

Claims (1)

[Claims] 1. In a pattern exposure apparatus that uses electron beams, X-rays, or light to form desired patterns on a substrate coated with a radiation-sensitive material, the substrate is exposed during or after exposure. A figure exposure device characterized by being maintained in a dry atmosphere. 2. Graphical exposure according to claim 1 above, characterized in that the exposure apparatus is provided with a substrate holding chamber for holding the substrate after exposure, and is replaced with an arbitrary gas or evacuated to a vacuum. Device. 3. The graphic exposure apparatus according to claim 2, wherein the optional gas is a dry gas with a relative humidity of 10% or less. 4. A graphic exposure apparatus according to claim 2, characterized in that the temperature of the atmosphere is -25 to 25°C. 5. A pattern exposure method according to claim 1, characterized in that a chemically amplified resist is used as the radiation-sensitive material. 6. A pattern exposure method according to claim 1, characterized in that the substrate is a wafer, a mask, or a reticle.