JPS59184525A - Formation of pattern - Google Patents

Abstract

PURPOSE:To enable the transference of further minute patterns by reducing the effect of developing slack of the part of secondary electron dispersion by irradiating synchrotron radiant ray onto the desired positions of a radiant ray sensitive thin film layer formed on a surface of the substrate so as to remove the radiant ray sensitive thin film layer directly. CONSTITUTION:Only the desired positions of a surface of a radiant ray sensitive thin film layer formed on a surface of the substrate 1 are irradiated with synchrotron radiant ray so as to remove a resist layer in the desired positions directly, thereby forming the necessary pattern. When the synchrotron radiant ray is projected onto the high molecular resist 3, not only cutting or crosslinking reaction of the resist molecular chain but also dissociation and elimination reactions of the direct resist high molecule caused by the radiant ray occurs. In some resist, the film of a slight thickness is left because of the crosslinking of the molecular chain which proceeds simultaneously to the light etching, but if ion etching is performed in the next process, the crosslinking layer 10 is removed completely.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pattern forming method suitable for large-scale transfer of mask patterns used in the manufacturing process of LSI elements having fine structures.

A conventional mask pattern transfer method will be explained step by step based on FIGS. 1(a) to 1(f), taking as an example the process of manufacturing a semiconductor element.

(1) Semiconductor crystal substrate 1 such as silicon used for device fabrication
An insulator layer 2 such as silicon oxide is grown thereon.

(2) A cyst 3 that is sensitive to an exposure beam 5 used for exposure such as an electron beam or an X-ray is coated on the insulating layer 2 (see FIG. 1(a)).

(3) Place the mask 4 on which the transfer pattern is drawn on the V cyst 3.

(4) An exposure beam 5 such as an electron beam, ion beam, or ultraviolet (X-ray) beam is irradiated from the mask 4 side. At this time, if the interaction between the exposure beam 5 and the atmosphere is large, such as with an electron beam, ion beam, or X-ray, exposure is performed in a vacuum device 6 evacuated to a high vacuum state (see Fig. 1). b)).

(5) After the exposed semiconductor crystal substrate 1 is taken out into the atmosphere and the mask 4 is removed, a chemical developer 7 is applied. At this time, if the resist 3 used is a positive type, the part that has reacted with the exposure beam 5 is removed, and if the resist 3 is a negative type, the part that has not reacted with the exposure beam 5 is removed. (See FIG. 1(c)) 0(6) The semiconductor crystal substrate 1 is placed in the vacuum device 6 again and irradiated with an etching beam 8 such as an ion beam, and then the above step (5) is performed. The portion of the insulator layer 2 where the cyst 3 has been removed is removed (see FIG. 1(a)).

(7) Insulating layer 2 is removed in step (6) and the underlying semiconductor crystal substrate 1 is injected with other elements by methods such as ion implantation and diffusion to activate the semiconductor element. Process 9 is performed (see FIG. 1(e)).

(8) The remaining V cysts 3 are removed using a stripping solution or plasma ion irradiation (see FIG. 1(f)).

In the steps (1) to (8) above, conventionally, exposure beams such as electron beams, ion beams, and X-rays, which require a high degree of vacuum, are used.
(see Figure 1(b)) and ion beam etching with the etching beam 8 (see Figure 1(d)).
and activation treatment such as ion implantation9
(See Figure 1 (, )) and chemical development treatment in the atmosphere (Figure 1 (C)).

Since the step (see (f)) coexists with the process, it is very complicated from the viewpoint of evacuation. Also, V cyst 3
In terms of pattern transfer characteristics, the resolution of the transferred image is
It is not only affected by the reaction characteristics between the V cyst 3 and the exposure beam 5, but also by the interaction characteristics between the / cyst 3 and the chemical developer I after the exposure reaction, which may cause problems such as development dripping. ,/Cyst 3 evaluation 2 complexity in selection.

It also introduced ambiguity and various limitations.

This invention was made in view of the above-mentioned points, and it irradiates the V-cysts with synchro-pn synchrotron radiation having high intensity, directly dissociating and detaching the V-cysts, thereby causing the above-mentioned problems. Omitting the chemical development process, which is the root cause,
Furthermore, there is a growing demand for dry processes in the semiconductor manufacturing process.

The object of the present invention is to provide a pattern forming method that facilitates consistent processing in a vacuum. An embodiment of the present invention will be described below with reference to the drawings.

Sink G7) Pn synchrotron radiation has a higher brightness (unit time) than conventional exposure beams such as ultraviolet rays and X-rays.

The amount of emitted energy per unit solid angle) is several orders of magnitude higher,
It also has a wide wavelength distribution from the X-ray region to the ultraviolet IfM region. When synchrotron radiation light, which has advantages different from conventional beams, is irradiated onto polymer cysts, it not only causes the scission and crosslinking reactions of cyst molecular chains, but also directly dissociates and detaches V-cyst polymers from the synchrotron radiation. A reaction occurs.

FIG. 2 is a diagram showing an example in which dissociation and desorption reactions of direct/cyst polymers occur due to irradiation with synchtron radiation light.

In the figure, the vertical axis shows the intensity H of secondary electrons emitted from the cyst when irradiated with synchrotron radiation, and the horizontal axis shows the total amount of synchrotron radiation energy E (7 nba·sec:
For convenience, the value is expressed as the unit of storage current of the electron storage ring x irradiation time. As is clear from the figure, when the amount of energy imparted by the synchrotron radiation per unit time is large (see the right side from point X in the figure), the intensity of the secondary electrons from the V cyst increases linearly.

The results of measuring the V cyst film thickness using Talystep show that this change in the intensity of secondary electrons from the cyst F corresponds to a change in the thickness of the cyst, that is, the direct dissociation and desorption development of the cyst polymer by synchrotron radiation. It has become clear from. For example, when EBR-9 (bundle V, polytrifluoroethyl α-ritoluacrylic V-) is used as V-cyst, the film thickness change is 110 A-aec total irradiation dose (for convenience, the accumulation of electron storage ring (value expressed in units of current x irradiation time) was ~0.9 μn1.

In the above embodiment, the electron current of the electron storage ring that generates synchrotron radiation is kept as high as possible, and the mask pattern is directly transferred onto the fusist during a photo-etching process using synchrotron radiation with high brightness. It becomes possible to obtain a cyst shape.

Depending on the V cyst, a slight film thickness may remain as shown in FIG. 3(a) due to molecular chain crosslinking that progresses simultaneously with photoetching. In the same figure, 1.2 f
Regarding the EBR-9/cyst 3 having a film thickness of i m, a molecular chain cross-linked layer (crosslink layer) 10 having a film thickness of 0.3 μm may remain in the synchrotron radiation irradiation area.

In this case, as shown in FIG. 3(b), if ion etching is performed in the next step, the crosslink layer 10 will be completely removed, and the resist 3 with a thickness of 0.9 μm will remain in the unirradiated area. You can get the structure that Therefore, the step of continuously ion etching the substrate in the opening can be performed without any problem, and the slight film remaining due to the crosslink layer 10 does not pose a practical problem.

According to the above-described embodiment, pattern transfer can be performed as a consistent process in vacuum as described above, so that it is possible to eliminate the trouble of repeatedly evacuation and to improve production efficiency.

In particular, in the production of semiconductor devices with three-dimensional structures, which will become increasingly necessary in the future, if conventional methods were followed, the complexity associated with evacuation operations would increase, but this example omits the process. It is thought that the value of this technology will further increase.

In addition, in the conventional chemical development process, since etching is performed by utilizing changes in development speed due to scission and crosslinking of cyst polymer chains, exposure by primary electrons excited by the exposure beam 5 (Figure 1) is performed. Dissipation of energy to the periphery of the area causes development sag, which is a major problem in improving the transfer resolution of the mask pattern.In contrast, the method of the above embodiment can reduce the M separation of the resist, which requires high energy density. This method utilizes an elimination reaction, and as shown on the left side of point It can be further reduced.

Therefore, finer pattern transfer than before is possible.

Although the semiconductor crystal substrate 1 is used in the above embodiment, other substrates may be used. Furthermore, the /cyst 3 is not limited to a positive type resist, but can be a negative type resist, an organic polymer film, or the like, in short, the same effect can be obtained as long as it is a radiation-sensitive thin film layer.

Incidentally, an example has been reported in which a pattern was formed by irradiating polymethyl methacrylate (PMMA) with a sensitizer for the ultraviolet region with an excimanzer source (Maihara et al.: Applied Physics Vol. 52, No. 1). (1983) ps3), but the present invention is completely different in that it can be applied to a commercially available radiation-sensitive thin film layer without the addition of a sensitizer, and almost all of the irradiated area can be removed.

As explained in detail above, the pattern forming method according to the present invention includes irradiating synchrotron radiation onto a desired location of the radiation-sensitive thin film layer formed on the surface of the substrate (directly removing the -1 radiation-sensitive thin film layer). As a result, it is possible to reduce the effect of development sagging in the secondary electron dissipation area, which was a problem with conventional etching methods, and it is therefore possible to transfer finer patterns than before.Furthermore, this invention This opens the way from evaluating resists that also consider their reaction characteristics to synchrotron radiation to simply focusing on their reaction characteristics to synchrotron radiation, providing greater flexibility in selecting resists used in the actual pattern transfer process. It has excellent advantages such as being able to increase the

[Brief explanation of drawings]

Figures 1 (a) to (f) are diagrams for explaining the conventional manufacturing process of semiconductor devices, Figure 2 is a diagram showing measurement results of photoetching development of cysts using synchrotron radiation, and Figure 3 (a) and (b) are diagrams for explaining a pattern forming method when a molecular chain crosslinked layer is present due to crosslinks. In the figure, 1 is a semiconductor crystal substrate, 2 is an insulating layer, 3 is a resist, 4 is a mask, 5 is an exposure beam, 6 is a vacuum device, and 7
8 is a chemical developer, 8 is an etching beam, 9 is an activation process, and 10 is a cross link (Fig. 1 (a) (f)) Fig. 2 (a) (b)

Claims (1)

[Claims] A radiation-sensitive thin film layer formed on the surface of a substrate is irradiated with synchronized p-n radiation only at desired locations on the surface, and the resist layer at the desired Φ locations is directly removed to form a desired pattern. How to form a pattern.