JPH08172044A - Phase shift mask and its production - Google Patents

Abstract

PURPOSE: To reduce a defect of phase shift mask using a half-tone material. CONSTITUTION: In a half-tone phase shift mask where a semi-transmissive member 2 having an opening 3 is adhered on a transparent substrate 1, the substrate 1 within the opening 3 is etched at a specified depth and removed, and the thickness of the member 2 is adjusted depending on such an etching depth that a phase difference of exposing light transmitting the opening 3 and non- opening part is π. In addition, A step where a member 2 is deposited on the substrate 1 and the member 2 is patterned to form the opening 3 and following step where the substrate 1 within the opening 3 is partly etched and removed in a depthwise direction are provided so as to adjust the thickness and etching depth of the member 2 in such a way that the phase difference of exposing light transmitting the opening 3 and non-opening part is π.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a halftone phase shift mask and its manufacturing method. The degree of integration of electronic devices is increasing year by year, and exposure technology with higher resolution is required. INDUSTRIAL APPLICABILITY The present invention can be used in a light projection exposure process in a wafer process for manufacturing semiconductor devices and the like.

[0002]

2. Description of the Related Art An optical projection exposure apparatus is widely used as an exposure apparatus for mass-producing electronic devices. In order to improve the resolution, an exposure method using modified illumination and an exposure method using a phase shift mask have been developed.

The factor that determines whether or not the phase shift mask, which is widely used, can be put to practical use depends on the defect-free mask manufacturing technique, and the defect inspection technique and the defect repair technique are important.

In that respect, it is difficult to inspect or modify a multi-layer type halftone mask in which the transmittance and the phase difference are controlled by different materials, and a halftone mask in which the quartz substrate is dug to control the phase difference. Therefore, it is difficult to put it into practical use.

On the other hand, a single-layer type halftone mask in which the transmittance and the phase difference are simultaneously controlled by one material is easy to manufacture, and is effective when applied to the patterning of the layer forming the contact hole. It is considered to be the closest to practical use because it is large.

Next, a conventional single layer type halftone phase shift mask will be described in the order of manufacturing steps with reference to FIG. FIG.
(A)-(C) is explanatory drawing of a prior art example.

In FIG. 3A, a semi-transmissive member 2 is deposited on a transparent quartz substrate 1. Then, a resist film 4 is coated on the semi-transmissive member 2, and an opening is formed by patterning by drawing with an electron beam or the like.

In FIG. 3B, dry etching is performed using the patterned resist film 4 as a mask to form the opening 3 in the semi-transmissive member 2. At this time, the etching residue 5 may remain on the quartz substrate in the opening.

In FIG. 3C, when the resist film 4 is ashed and peeled off, a phase shift mask is obtained. Here, the thickness of the semi-transmissive member 2 is adjusted so that the phase of the transmitted light at the opening 3 of the semi-transmissive member 2 coated on the transparent quartz substrate 1 and the phase of the transmitted light at the non-opening are shifted by π.

In this mask, the transmittance of the single-layer halftone material at the wavelength of the inspection light (633 nm or 488 nm) used in the conventional defect inspection apparatus is generally high, and a sufficient contrast for the inspection can be obtained. Therefore, it was difficult to improve the inspection accuracy. Moreover, since the dry etching technique is mainly used for patterning the semi-transmissive member, defects due to the etching residue 5 are the largest in the defect modes.

[0011]

Since the conventional single-layer halftone has poor inspection accuracy, on the one hand, it is required to improve the accuracy of the inspection technique. On the other hand, the mask which suppresses the occurrence of defects generated during the mask fabrication. Development of structure and manufacturing process is desired.

An object of the present invention is to reduce defects in a phase shift mask using a halftone material.

[0013]

To solve the above problems, 1) in a halftone phase shift mask in which a semi-transmissive member having an opening is deposited on a transparent substrate, the transparent substrate in the opening has a predetermined depth. Or a phase shift mask in which the thickness of the semi-transmissive member is adjusted according to the etching depth so that the phase difference of the exposure light transmitted through the opening and the non-opening becomes π. 2) A step of depositing a semi-transmissive member on the transparent substrate and patterning the semi-transmissive member to form an opening, and then a step of partially etching away the transparent substrate in the opening in the depth direction. And the thickness of the semi-transmissive member and the etching depth are adjusted so that the phase difference of the exposure light transmitted through the opening and the non-opening is π.

[0014]

[Function] In the conventional mask manufacturing process, it is very difficult to manufacture a defect-free mask with a high yield because the etching residue is likely to be generated after the dry etching process as described above, and the inspection and correction technique is not established. But,
In the manufacturing process according to the present invention, the etching residue in the opening is peeled and removed together with the quartz surface by wet etching, so that the occurrence of defects is reduced and a defect-free mask can be easily obtained.

FIG. 1 illustrates the principle of the present invention. In the figure, a semi-transmissive member 2 is deposited on a transparent quartz substrate 1, and the quartz substrate in an opening 3 in which the semi-transmissive member is patterned is removed by etching to a depth of several tens to several hundreds of liters.

At this time, it is needless to say that the thickness of the semi-transmissive member is reduced as compared with the conventional example according to the etching depth so that the phase difference between the exposure light transmitted through the opening and the non-opening becomes π.

[0017]

EXAMPLE FIGS. 2A to 2C are explanatory views of an example of the present invention. As shown in Fig. 2 (A), a semi-transmissive member 2 having a thickness of 12
Apply 00Å chromium oxide film.

Then, a resist film 4 is formed on the semi-transmissive member 2.
Then, an opening is formed by patterning by coating with an electron beam or a laser beam and patterning. In FIG. 2B, using the patterned resist film 4 as a mask,
Dry etching is performed, and the semi-transparent member 2 has an opening 3
To form. At this time, the etching residue 5 may remain on the quartz substrate in the opening.

An example of dry etching conditions at this time is as follows. Reaction gas: CH ₂ Cl ₂ + O ₂ Gas pressure: 0.28 Torr RF power: 300 W In Fig. 2 (C), wet etching using hydrofluoric acid was performed to bring the quartz substrate at the opening to a depth of 100 Å, along with the etching residue 5. Remove by etching.

Next, the resist film 4 is ashed and peeled off to obtain the mask of the present invention shown in FIG.

[0021]

According to the present invention, it is possible to reduce defects in a phase shift mask using a halftone material, and it is possible to easily obtain a defect-free mask.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is an explanatory diagram of an embodiment of the present invention.

FIG. 3 is an explanatory diagram of a conventional example.

[Explanation of symbols]

 1 Transparent quartz substrate 2 Semi-transmissive member 3 Opening of semi-transmissive member 4 Resist film 5 Etching residue

Claims (2)

[Claims] 1. A halftone phase shift mask in which a semi-transmissive member having an opening is deposited on a transparent substrate,
The transparent substrate in the opening is removed by a predetermined depth by etching, and the thickness of the semi-transmissive member is adjusted according to the etching depth so that the phase difference between the exposure light passing through the opening and the non-opening becomes π. The phase shift mask is characterized in that 2. A step of depositing a semi-transmissive member on a transparent substrate and patterning the semi-transmissive member to form an opening.
Next, there is a step of partially etching away the transparent substrate in the opening, and the semitransparent member of the semi-transmissive member is adjusted so that the phase difference of the exposure light transmitted through the opening and the non-opening becomes π. A method of manufacturing a phase shift mask, characterized in that the thickness and the etching depth are adjusted.