JPS62166519A - Formation of pattern - Google Patents

Abstract

PURPOSE:To improve the resolution by covering a substrate with a positive resist, emitting an ion beam to a pattern forming region on the resist to form a modified layer, and removing the resist except the region where the modified layer is formed. CONSTITUTION:A silicon substrate 1 is covered with a positive resist 2, and with a shielding plate 3 opened in a pattern as a mask P ion P<+> beam is emitted on the resist 2 to be implanted. Then, a modified layer 4 is formed by P<+> implanting, and the resist 2 except a region under the layer 4 is removed by a down flow type etching unit using O*. Then, the pattern of the resist having the same shape as the layer 4 is obtained. A part of the thickness of the resist 2 may be converted to the layer 4, or the entire thickness may be converted.

Description

[Detailed Description of the Invention] [Summary] Ions of boron (B), 2 (P), etc., which are used as dopants in normal semiconductor processes, are implanted into a positive resist to form a pattern of an altered layer. Chemical plasma etching using oxygen radicals (0'') is used to remove the other positive resist, leaving a pattern of the altered layer, to form a fine resist pattern.

[Industrial application field]

The present invention relates to a novel method for forming fine resist patterns using ion implantation and dry development.

As semiconductor integrated circuits become more complex and miniaturized, conventional single-layer resist technology approaches its accuracy limit, and two- or three-layer resist technology has come to be used.

However, multilayer resist technology requires a large number of steps and is troublesome, and the resolution is limited to a pattern of about 0.8 μm, so a new technology is required to further increase the resolution.

[Conventional technology]

Many multilayer resist techniques have been reported to improve substrate flatness (topography, step coverage) and surface reflectance (resolution) for fine pattern formation.

For example, a two-layer resist process may include depositing polymethyl methacrylate I'HMA as a thick planarization layer;
A novolak-naphthoquinone diazo positive resist is deposited thereon.

In addition, the three-layer resist process first patterns a thin high-resolution resist as the top layer, transfers it to a thin silicon dioxide (SiOz) layer as an intermediate layer, and finally etches it using reactive ion etching (RIE). This method uses directional etching to retransfer onto the underlying resist.

When the above three-layer resist process is used, many problems caused by unevenness of the substrate can be solved because the substrate is flattened, and the resolution is improved because anisotropic etching is used.

However, the three-layer resist process complicates the process as described above, and also requires corresponding equipment.

The two-layer resist process simplifies the process by selecting a material that has both the roles of the top layer and the middle layer.

[Problem that the invention seeks to solve]

Conventional fine pattern forming techniques have a limited resolution and are difficult to form 0.5 μm patterns.

Moreover, the process becomes complicated.

[Means for solving problems]

The solution to the above problem is to deposit a positive resist on the substrate,
A pattern forming method comprising: irradiating a pattern formation area on the positive resist with an ion beam, forming an altered layer corresponding to the pattern on the positive resist, and removing the positive resist other than under the area where the altered layer is formed. This is achieved by

For example, ion beam irradiation may be performed using a shielding plate with a patterned opening as a mask.

[Effect]

The removal (peeling) of the positive resist mainly composed of novolac resin is performed using chemical plasma etching according to 02 or the like. At this time, the reaction starts from the azide group in the side chain, progresses, and finally the survival collapses.

The present inventor discovered the phenomenon that the above reaction is difficult to occur in a modified layer in which B, P, etc. are attached to the side chain, and formed a patterned modified layer on a positive resist, developed it, and processed a single layer resist. We have developed a fine pattern formation technology with improved resolution.

The resolution in this case is determined by the aperture accuracy of the shielding plate and the accuracy of direct writing using an ion beam, and is improved compared to conventional resist patterning accuracy.

〔Example〕

FIGS. 1(1) to 1(3) are cross-sectional views illustrating a method for forming a fine resist pattern according to the present invention.

In FIG. 1 (1), 1 is a substrate, and a silicon (Si) substrate is used, and a positive resist 2 with a thickness of 1 μm is applied on this substrate.
Apply PR (manufactured by Tokyo Ohka).

Next, mask the shielding plate 3 with the pattern opened, and
An ion beam is irradiated onto the positive resist 2 for implantation.

The P1 implantation conditions are an energy of 60 KeV and a dose of 3×10"cm-".

In Figure 1 (2), the thickness is 0.1 μm due to P injection.
A deteriorated layer 4 is formed to a certain extent.

Next, the positive resist 2 other than the area under the altered N4 is removed by a downflow type etching device using 0''.

In FIG. 1(3), a pattern of the positive resist 2 having the same shape as the altered layer 4 is obtained.

In this example, a part of the thickness of the positive resist 2 is converted into the altered layer 4, but the entire thickness may be converted.

Furthermore, by changing the ion implantation angle, it may be possible to control the cross-sectional profile of the resist pattern.

Figure 2 shows the downflow type O” used to implement the present invention.
FIG. 3 is a sectional view of the etching device.

In the figure, 21 is a reaction vessel, 22 is an exhaust port, 23 is an oxygen inlet, 24 is a substrate holder, 25 is a substrate, 26, 2
7 is an electrode, and 28 is a radio frequency (RF) power source.

The substrate 25 with the altered layer 4 formed thereon is placed on the substrate holder 24, the reaction vessel 21 is evacuated from the exhaust port, oxygen is introduced from the oxygen introduction port 23, and RF power is applied between the electrodes 26 and 27 by the RF power source 28. Etching is performed by causing the 01 generated during etching to flow down onto the substrate 25.

〔Effect of the invention〕

As described above in detail, the fine pattern forming technique according to the present invention improves resolution and can reliably form a 0.8 μm pattern. Furthermore, the process is simple, using single-layer resist technology and ordinary ion implantation.

[Brief explanation of drawings]

Figures 1 (1) to (3) are cross-sectional views explaining the method of forming a fine resist pattern according to the present invention, and Figure 2 is a down-flow type 0* used in implementing the present invention.
FIG. 3 is a sectional view of the etching device. In the figure, 1 is a substrate (Si substrate), 2 is a positive resist (0FPR) (Tokyo Ohka type), 3 is a shielding plate with an opening pattern, 4 is a modified layer injected with P, 21 is a reaction vessel, and 22 is an exhaust port. , 23 is an oxygen inlet, 24 is a substrate holder, 25 is a substrate, 26.27 is an electrode, and 28 is an RF power source.

Claims (1)

[Claims] A positive resist is deposited on a substrate, a pattern formation area on the positive resist is irradiated with an ion beam, an altered layer corresponding to the pattern is formed on the positive resist, and a layer other than the area under the altered layer is formed. A pattern forming method characterized by removing the positive resist.