KR980011702A - Method for manufacturing multiple exposure phase inversion mask - Google Patents

Abstract

A method of manufacturing a phase inversion mask by multiple exposure that can be applied to a layer having a repetitive pattern will be described. Forming a mask pattern layer made of an opaque material on a circular plate of a mask and then exposing the mask original plate in an area where light deterioration has occurred using an electron beam to adjust the depth of focus of the mask original plate, The phase inversion portion of the mask pattern can be formed by allowing the phase inversion in the peripheral portion of the mask pattern. The phase inversion mask produced by the above-described multiple exposures can be applied to a contact layer, an active layer, an S-poly layer, and a pad-poly layer having a repetitive pattern.

Description

Method for manufacturing multiple exposure phase inversion mask

Since this is a trivial issue, I did not include the contents of the text.

The present invention relates to a method of manufacturing a phase-shifting mask (PSM), and more particularly, to a method of manufacturing a phase-reversal mask by multiple-exposure.

In order to actually form the circuit elements arranged by the design on the surface of the silicon wafer, the circuit diagram must be transferred to a plurality of masks. This mask is used for a chip by using a PG tape containing the data of the design drawing Create a reticle and then transfer it to a mask to create a master mask. In a mask, there are several reticles corresponding to the pattern of each chip so that several chips can be formed on the wafer.

Various patterns of a semiconductor device are formed by a technique of photolithography, which is a technique of reproducing a shape on a specific substrate using light. According to the photolithography technique, a photoresist film whose solubility is changed by irradiation of light such as X-rays or ultraviolet rays is formed on a film on which a pattern is to be formed, such as an insulating film or a conductive film on a semiconductor wafer, A portion having high solubility is removed by development to form a photoresist pattern, and an exposed portion of the film to be patterned is removed by etching to form various patterns such as wiring and electrodes.

In order to form a finer pattern in accordance with the trend of high integration and high density of semiconductor devices in recent years, exposure methods using electron beams, ion beams or X-rays, deformation illumination methods using diffracted lights of strong sources, techniques of new resist materials and resist processing methods This research is being developed.

Generally, the most popular photographic technique for pattern formation below the critical pattern is a phase reversal mask.

A method using a phase shift mask is a method of exposing a pattern using a mask including a phase shifter. The phase inversion mask exposes a pattern of a desired size using interference or partial interference of light, thereby increasing resolution or depth of focus. That is, when light passes through the mask substrate or through the shifter film, the wavelength is shortened to a value obtained by dividing the wavelength in vacuum by the refractive index. Therefore, there is a difference in the light of the same phase depending on the presence or absence of the shifter. Since the light passing through only the light transmitting portion and the passing light passing through the shifter are in opposite phase to each other, when the shifter is positioned at the edge of the mask pattern, the intensity of light becomes zero at the boundary portion of the pattern, and the contrast increases.

This phase inversion mask is advantageous in that it is economical because it uses only the mask without modification of the conventional illumination system unlike the conventional fine pattern formation method, and the resolution can be improved by reversing the diffraction of light only by changing the mask manufacturing method have.

In the phase inversion mask using the above principle, an alternating phase-shifting mask (MASK) in which electric field waves are relatively opposite between two lines by arranging shifters alternately in the case where the line space is repeatedly dense, A supplementary shifter additive mask with a phase shift shifted by a small auxiliary pattern below the resolution of the pattern, a peripheral effect enhanced mask (Rim Shifter MASK) with only a pattern edge portion formed by shifting around all the patterns, A chromeless phase shifting mask (MASK) using a principle that the light amount at the interface of the phase shifter becomes zero, a method of increasing the transmittance of the light shielding portion from 0 to a value other than 0, And an attenuated phase shifting mask using the canceling effect.

The present invention corresponds to an alternating phase-shifting mask in the phase inversion mask.

A typical phase inversion mask is a quartz-type phase-shifting mask. In a general phase inversion mask, an undercut method is mostly used in the fabrication process. A method of fabricating such a phase inversion mask is disclosed in, for example, Pattern-Depent Correction of Mask Topography Effects for Alternating Phase-shifting Masks (SPIE Vol. 2440, pp. 349-360).

Figs. 1A to 1C are cross-sectional views showing a manufacturing method of a conventional phase inversion basque disclosed in the above document.

As shown in FIG. 1A, a quartz and a glass plate 110 are used as a mask, and a thin film is formed on the glass plate 110 with an opaque chromium 112 or the like capable of blocking light. A photoresist film 114 is formed on the chromium film 112 by applying a photoresist, which is a material exposed to an electron beam, by a spin coating method.

Next, as shown in FIG. 1B, the photoresist film 114 is exposed by scanning the electron beam. Next, the exposed resist film 114 is developed using a developer to form a resist pattern 114 '. Using the resist pattern 114 'as an etching mask, the chromium film 112 of the portion where the resist is removed is etched to form a mask pattern 112'. Next, the isotropic etching process for performing the first anisotropic etching process on the quartz glass plate 110 using the resist pattern 114 'as an etching mast to form a second undercut region may be performed, The etch rate of the anisotropic etch process is less than the vertical etch rate.

Next, as shown in FIG. 1C, the residual photoresist pattern 114 'is stripped and removed to complete the phase reversal mask.

The phase inversion mask manufactured according to the above process has a high probability of expanding the quartz of the blank mask, and there is a high possibility that a chipping phenomenon occurs in which fragments are separated from the chrome portion. In the completed mask, even if chipping occurs in chromium, chipping of the mask can not be corrected, and therefore, the mask can not be used. Also, in order to reduce the amount of undercut of the quartz, a method of previously adjusting the distance between the phase reversal portion and the neighboring pattern in an area where a light drop phenomenon occurs, in which an electron beam is reduced, However, this method is limited to a specific layer (later).

2. Description of the Related Art In recent years, in order to form a finer pattern in accordance with the trend toward higher integration and higher density of a semiconductor device, a difference in critical dimension between a phase inversion portion and a neighboring pattern is reduced and a margin .

SUMMARY OF THE INVENTION The present invention provides a method for fabricating a phase shift mask which forms a shifter by selectively exposing quartz.

Figures 1a to 1c are cross-sectional views illustrating a conventional phase shift mask fabrication process.

FIGS. 2a to 2c are cross-sectional views illustrating a manufacturing process of a phase reversing microrescope according to the present invention.

Figure 3a is a cross-sectional view showing the difference in critical dimension between the phase inversion portion and the neighboring pattern.

3b is a graph according to an experimental value showing the result of correcting the difference in the critical dimension between the phase inversion portion and the neighboring pattern by adjusting the amount of the electron beam according to the present invention.

FIG. 4 illustrates a device layer to which the method of the present invention may be applied.

DESCRIPTION OF THE REFERENCE NUMERALS

10: Quartz 20: Chrome

30: photoresist film

In order to provide a method of manufacturing a phase shift mask as described above, the present invention provides a method of manufacturing a phase shift mask, including: forming a mask pattern layer made of an opaque material on a circular substrate; And the mask original plate in a region where light deterioration has occurred is exposed using an electron beam to control the focus depth of the mask original plate so that the phase can be reversed at the peripheral portion of the mask pattern alternately, And forming an inversion portion in the phase shift mask.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

2A to 2C are cross-sectional views illustrating a manufacturing process of a phase shift mask according to an embodiment of the present invention.

2A, an opaque layer 20 made of opaque chromium-like material capable of blocking light on the mask substrate 10 using a mask substrate 10 made of a transparent material such as quartz or the like, . A photoresist, which is a material exposed to an electron beam, is coated on the opaque layer 20 by a spin coating method to form a photoresist film 30. Next, the electron beam is scanned to expose the photoresist film 30, and then the exposed photoresist film 30 is developed with a developing solution to form a resist pattern. Next, as shown in FIG. 2B, the resist pattern is used as an etching mask to etch away the opaque layer 20 where the resist is removed, and then the remaining photoresist pattern is stripped to form a mask composed of an opaque material Thereby forming a pattern 20 '.

Next, as shown in FIG. 2C, the amount of electronic ice is adjusted so as to have a phase reversing effect on the peripheral portion of the pattern alternately on the mask substrate 10 in the region where light deterioration has occurred And the shifter layer 25 is formed by adjusting the depth of focus by exposure.

The method can be applied to a layer having a repetitive pattern by completing the mask by arbitrarily correcting the difference in the critical size between the phase inversion portion and the neighboring pattern on the mask.

3A is a cross-sectional view showing a difference in critical dimension (CDI, CD2) between a phase inversion region and a neighboring pattern appearing in a region where a light drop phenomenon occurs.

FIG. 3D is a graph according to an experimental value showing the result of correcting the difference in the critical dimension between the phase inversion portion and the neighboring pattern by adjusting the amount of the electron beam according to the present invention. When the difference in the critical dimension between the phase reversal region and the neighboring pattern is observed according to the amount of the electron beam, the difference in critical dimension between the amount of the electron beam of 0.1 mu c / cm < 2 & It shows that there is change.

If the difference in the critical dimension between the phase inversion portion and the neighboring pattern on the mask is about 0.05 mu m, the difference on the wafer is about 0.01 mu m. I will not receive it.

FIG. 4 shows patterns of a device layer to which the method of the present invention can be applied.

In the case of applying the present invention, a phase inversion mask, which was applicable only to a conventional line and space, can be formed by adjusting the difference in the critical dimension, thereby forming a contact layer having a repetitive pattern, , A storage electrode-poly (S-poly) layer, a pad-poly layer, or the like. Particularly, in the case of the contact layer, since the difference in critical dimension is very serious, it is necessary to control the contact critical dimension on the mask very finely. In the case of the present invention, since the contact critical dimension can be arbitrarily adjusted, it is possible to prevent the margin of the depth of focus from being lowered due to the difference in the critical dimension. An active layer, a storage electrode-poly-layer, a pad-poly layer, or the like. Particularly, in the case of the contact layer, since the difference in critical dimension is very serious, it is necessary to control the contact critical dimension on the mask very finely. In the case of the present invention, since the contact critical dimension can be arbitrarily adjusted, it is possible to prevent the margin of the depth of focus from being lowered due to the difference in the critical dimension. As in the case of the contact layer, the depth of focus could be improved in the active layer, the storage electrode-poly-layer, and the pad-poly layer.

Although the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, it is to be understood that the present invention is not limited thereto and various modifications and changes may be made by those skilled in the art without departing from the scope of the present invention.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of fabricating a phase shift mask which forms a shifter by selectively exposing quartz to overcome various problems inherent in conventional phase shift masks.

Claims (1)

Forming a mask pattern layer made of an opaque material on a circular plate of the mask; And the mask original plate in a region where light deterioration has occurred is exposed using an electron beam to adjust the focus depth of the mask original plate so that the phase can be inverted at the peripheral portion of the mask pattern alternately, And forming an inversion region on the surface of the phase shift mask. ※ Note: It is disclosed by the contents of the first application.