JPS60260037A - X-ray resist material - Google Patents

Abstract

PURPOSE:To prevent reduction in the sensitivity due to the dependency on atmosphere by incorporating amines into sensitive resin. CONSTITUTION:The photon energy of soft X-rays radiated from an X-ray source is absorbed in the sensitive resin part of an X-ray resist by the photoelectric effect, and photoelectrons or Auger electrons having a certain extent of energy are released in the X-ray resist from atoms in the sensitive resin part. The secondary electrons produced in the sensitive resin part produce excited molecules, atoms or ions in the X-ray resist, and various free radicals are produced from the excited or ionized matter. A reaction such as cross-linking takes place in the X-ray resist by a reaction between the free radicals, and the patterning of the resist by the irradiation of X-rays is attained. When amines are incorporated into the X-ray sensitive resin, the effect of oxygen in exposure atmosphere can be absorbed by the amines as an antioxidant, so an X-ray resist material having fixed sensitivity independently of atmosphere is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an X-ray resist material in the field of X-ray phosphorography, which is effective in copying fine patterns of 1 μm or less.

(Prior art and its problems) X-ray exposure technology is expected to be an extremely promising copying technology in the future due to its reliable high resolution of submicron width patterns, and is currently being actively researched and developed in various places. It is being said. The present inventor has also been involved in research on XS exposure technology, and discovered one important problem. Figure 1 shows experimental facts that seem to be problematic.

This figure shows characteristic X-rays (in this case MoL with a wavelength of 5.41A).
cl@) is directly irradiated without passing through a negative resist PGMIC1 X-ray mask, the dependence of the remaining PGMA film thickness on the exposure atmosphere air pressure is shown. The MoLa wire dose was set at 66 m'/era to obtain a residual film thickness of ~60 mm in a low-pressure air atmosphere.

As the pressure increases, the absorption of characteristic X-rays increases in the air atmosphere, so in that case the exposure time was adjusted to give a dose of 66 m'/cd to PGMA. As can be seen from Figure 1, as the pressure increases,
The remaining PGMA film thickness is considerably reduced. Although the detailed mechanism of such a phenomenon in negative resists, that is, the reduction reaction of crosslinking due to an increase in air pressure, has not been elucidated, it has been experimentally recognized that it is an effect of oxygen in the air. For example, a similar effect is pointed out in a publication published in 1975, Journal of Vacuum Science and Technology (J, Vac, 8ci, Technol, ), Erimikabu, pages 2020 to 2024. Figure 1 means that the sensitivity of the PGMA resist decreases with increasing aerodynamic forces.

In the figure, the maximum pressure is 2670 Pa, and the residual film thickness at that time has dropped from about 55% at low pressure to about 35%. In Figure 2, the PdLa line (
A similar pressure dependence is shown using a wavelength of 4.37 A). In this case as well, the present koji is almost the same as in Figure 1, and the remaining film thickness at a pressure of 2670 Pa is
It has dropped from the value of about 55% at low pressure to about 34%.

The above-described large change in the sensitivity of the resist with respect to the air pressure of the exposure atmosphere is a problem in X-ray exposure technology from the following viewpoints. At present, the exposure atmosphere of the X-ray exposure system can be vacuum, He gas, or atmosphere (air), and the optimal atmosphere has not been determined. The air pressure area in Figures 1 and 2 is 6.7
~267QPa, but the fact that the residual film thickness varies greatly as shown in the figure is a major hindrance in device fabrication where it is necessary to obtain a predetermined residual film thickness. The above is the first viewpoint. The second point is related to the atmospheric exposure method. The atmospheric exposure method is excellent in the ease of designing and configuring an X-ray exposure system, and is considered to be a promising exposure method in the future. This advantage is particularly easy to take advantage of in step-and-repeat systems. However, as can be seen from Figure 1.2, in the atmosphere (~105P'a), the sensitivity is expected to drop significantly. This is because the aforementioned crosslinking reduction reaction due to oxygen becomes extremely large. Decrease in resist sensitivity is a serious problem because it is directly related to throughput in X-ray exposure. A major challenge for the future of X-ray exposure is increasing throughput. One major means of achieving this high throughput is the development of a highly sensitive X-ray resist.

A highly sensitive resist is easily obtained, for example, as a negative resist. However, in this high-sensitivity negative resist, the first,
If a decrease in sensitivity due to atmosphere dependence is observed as shown in Figure 2, this is a serious problem.

(Objective of the Invention) An object of the present invention is to eliminate such conventional drawbacks and to provide an X-ray resist material that exhibits constant sensitivity regardless of changes in exposure atmosphere.

(Structure of the Invention) According to the present invention, in an X-ray resist material used for X-ray exposure in which an X-ray sensitive resin formed on a substrate is exposed by irradiating X-rays, the sensitive resin has amines. An X-ray resist material is obtained which is characterized by containing the following.

(Detailed explanation of configuration) The configuration of the present invention will be explained below.

An outline of the sensitivity mechanism of an X-ray resist during X-ray exposure is as follows. Photon energy of soft X-rays with a wavelength of several to several tens of amperes emitted from an X-ray source is absorbed by the sensitive resin portion of the X-ray resist due to the photoelectric effect. Photoelectrons or Auger electrons with a certain amount of energy are emitted into the X-ray resist from the atoms of the sensitive resin portion that have absorbed the photon energy. The magnitude of the energy of these secondary electrons is the value obtained by subtracting the binding energy value of bound electrons within the atom from the photon energy value of the incident soft X-ray.

In this way, the secondary electrons generated in the sensitive resin part are
Excited molecules, atoms, ions, etc. are generated within the line resist. Various free radicals are generated from these excited or ionized substances.

Finally, the reaction between these free radicals results in x#! Reactions such as crosslinking occur within the resist, and patterning of the resist is achieved by X-ray irradiation. Currently, the negatives used as Xi resists include COP (developed by Bell Laboratories, USA), PGMA (developed by Hitachi), and 5EL-N.
(developed by Somar Industries), OFI C circuit), etc., and for positive, 1'BS (developed by Bell Laboratories), FB
M and FPM (developed in a round trip), etc. Each resist includes a sensitive resin portion that is sensitive to X-rays.

However, as mentioned above as a problem, if the normal reactions are reduced by oxygen in the air, serious problems occur. This effect of oxygen is often particularly noticeable in negative resists, but it can also occur in positive resists. this is,
As explained above, reactions such as crosslinking of X-ray resists are dominated by reactions between free radicals generated by secondary electrons, but it is possible that oxygen is involved in some form in the reactions between these free radicals. This seems to mean that it is strong.

Alternatively, there is also the idea that oxygen cuts the main chain of the sensitive resin part of the X-ray resist, and in the case of a negative resist, this obviously promotes the reduction of crosslinking. In short, although the detailed mechanism is still not clear, it seems certain that oxygen serves as an X-ray resist to normal X-rays and blocks the reaction.

Therefore, in the present invention, an amine is included in a sensitive resin that is sensitive to X-rays. Amines have the effect of antioxidants. For example, phenyl-β-naphthylamine, other aromatic amines, aldehyde amine condensates, etc. can be used as antioxidants for purified rubber and synthetic rubber. Also, phenyl-α
- Naphthylamine and other aromatic amines can be used as antioxidants in lubricating oils. Amines are compounds in which the hydrogen atom of ammonia is substituted with a hydrocarbon residue R, and the primary amine R-NH depends on the number of substituted hydrocarbon residues.
,, tertiary amine 几, >NH, tertiary alkyl group (violet or its substituted product) is called aliphatic amine, R
An aromatic amine is one in which all or part of the aromatic hydrogen residue (phenyl group or its substituted product) is an aromatic hydrogen residue (phenyl group or its substituted product).

Methylamine 0H3NH,, ethylamine OH, OH,
NH, etc. belong to aliphatic primary amines. Dimethylamine (OH, ), NH.

Diethylamine (Ox Hs), NH, etc. belong to aliphatic secondary amines. Trimethylamine (OHs)
N.

Triethylamine (Os H5)s N etc. belong to fatty tertiary amines, allylamine OH,=OHOH,NH, etc. belong to aliphatic unsaturated amines, cyclopropylamine 0
．． H, NH, etc. belong to alicyclic amines, and aniline 0,
HIINH, , Methylaniline 06H5NHOH,
etc. belong to aromatic amines.

All amines have an antioxidant function, and this point is effectively utilized in the present invention. In other words, if an X-ray resist material having a sensitive resin part containing amines is used, the effect of oxygen in the exposure atmosphere can be absorbed by the amines, which are antioxidants, and the resist has constant sensitivity regardless of the atmosphere. X
A line resist material is obtained and the object of the invention is achieved.

As the base resist material, any material that is sensitive to X-rays can be used; if the content of amines is too low, the oxidation prevention function will be insufficient, and if the content is too low, the sensitivity of the resist will decrease. Therefore, it is preferable that the weight ratio is in the range of several percent to several tens of percent, preferably several percent to 20 percent, based on the base X-ray sensitive resin.

To obtain an X-ray resist containing amines, basically, it is sufficient to simply mix the amine with a normal X-ray resist.

In addition, the method of using the X-ray lugist of the present invention is to apply it on the substrate in the same way as usual, in a state in which it is dissolved in a solvent. In some cases, for example, a resist containing amines may be thinly applied, and then a resist containing amines may be applied thereon.

(Effects of the Invention) As explained above, according to the present invention, firstly, high-throughput X-ray exposure using a high-sensitivity X-ray resist becomes more reliable regardless of the exposure atmosphere, and secondly, high-throughput X-ray exposure using a high-sensitivity It provides greater latitude when developing line resists (i.e., sensitivity reduction due to reaction with oxygen does not need to be considered), and thirdly, XIi! i! A degree of freedom can be given to system design such as exposure atmosphere during exposure.

[Brief explanation of drawings]

FIGS. 1 and 2 are diagrams showing the dependence of the residual film thickness of the resist (ie, sensitivity) on the exposure atmosphere air pressure, which is a problem in the prior art. Figure 1 Pressure (PO) Figure 72 Pressure (PO)

Claims (1)

[Claims] An X-ray resist material used for X-ray exposure in which an X-ray sensitive resin formed on a substrate is irradiated with X-rays, characterized in that the sensitive resin is injected with amines. X-ray resist material.