JPH0749558A - Production of phase shift mask - Google Patents

Abstract

PURPOSE:To precisely form a light transmitting region and a phase shift region into desired pattern shapes. CONSTITUTION:A phase shift material layer 26, a light shielding layer 22 and a silicon dioxide layer 24 are successively formed on the surface of a substrate 20 (a). The silicon dioxide layer 24 is dry-etched into a desired pattern shape (b), the light shielding layer 22 is dry-etched with the silicon dioxide layer 24 as an etching mask (c) and the shift material layer 26 is dry-etched with the light shielding layer 22 as an etching mask to produce the objective phase shift mask (d).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a phase shift mask including a halftone phase shift mask.

[0002]

2. Description of the Related Art A photomask used in a pattern transfer process, that is, a so-called lithography process in manufacturing a semiconductor device is used for transferring a pattern shape on the photomask onto a resist material formed on a wafer. The dimensions of pattern processing in semiconductor devices and the like are becoming finer year by year. A conventional photomask provided only with a pattern region composed of a light-shielding region and a light-transmitting region cannot obtain a resolution of about the wavelength of the exposure light of the exposure apparatus used in the lithography process, and the semiconductor device It is becoming difficult to obtain the required resolution in the manufacture of the above. Therefore, in recent years, so-called phase shift masks having a phase shift region that makes the phase of light different have been used in place of such conventional photomasks. By using a phase shift mask, it is possible to form a fine pattern that cannot be formed by a conventional photomask.

A conventional method of manufacturing a phase shift mask will be described below with reference to FIGS. In the conventional method of manufacturing a phase shift mask described below, the case where a positive resist is used as a resist will be described as an example.

First, a conventional method of manufacturing a phase shift mask having a structure in which a phase shift material layer having a function of shifting the phase of light is formed between a light shielding layer and a transparent substrate will be described with reference to FIGS. It will be described with reference to FIG.

[Step-10A] The phase shift material layer 26 is formed on the transparent substrate 20 made of, for example, quartz by applying, for example, SOG (spin on glass). Next, a light shielding layer 22 made of, for example, chromium is formed on the phase shift material layer 26 by a sputtering method, and further,
A resist layer 30 is formed on the light shielding layer 22. As a result, the structure shown in FIG. 15A is obtained.

[Step-20A] Next, a drawing step using an electron beam from a drawing apparatus, a developing step for the resist layer 30 (see FIG. 15B), and an etching step for the light shielding layer 22 ((C in FIG. 15). )), And the structure shown in FIG. 15D is obtained through the peeling process of the resist layer 30.

[Step-30A] After that, a resist layer 32 is formed on the entire surface, and an antistatic layer 34 is further applied thereon (see FIG. 16A). Then, a structure shown in FIG. 16B is obtained through a drawing process using an electron beam from a drawing device and a developing process of the resist layer 32.

[Step-40A] Next, the phase shift material layer 26 is etched using the light shielding layer 22 as an etching mask (see FIG. 16C), and the resist layer 32 is formed.
Is peeled off to finally obtain the structure shown in FIG. The portion where the phase shift layer 26 is removed is the light transmission region 1
Equivalent to 0. The portion where the light shielding layer 22 is removed and the phase shift material layer 26 is left corresponds to the phase shift region 14. Further, the portion where the light shielding layer 22 and the phase shift material layer 26 are left corresponds to the light shielding region 12.

Next, a conventional method of manufacturing a phase shift mask in which a recess is formed by etching a transparent substrate will be described below with reference to FIGS. 17 and 18.

[Step-10B] For example, a light shielding layer 22 made of chromium, for example, is formed on the transparent substrate 20 made of quartz by a sputtering method, and a resist layer 30 is applied on the light shielding layer 22 (see FIG. 17). (See (A)).

[Step-20B] Next, a drawing step with an electron beam from a drawing apparatus, a developing step of the resist layer 30 (see FIG. 17B), and an etching step of the light shielding layer 22 (see FIG. 17). (See (C)), and the structure shown in (D) of FIG.

[Step-30B] After that, the resist layer 32 is formed.
Is formed, and the antistatic layer 34 is further applied thereon (see FIG. 18A). Then, a drawing process using an electron beam from the drawing device and a developing process of the resist layer 32 are performed (see FIG. 18B).

[Step-40B] Next, using the light shielding layer 22 as an etching mask, the substrate 20 is etched, the resist layer 32 is peeled off, and the structure shown in FIG. 18D is finally obtained.

[0014]

However, the conventional method of manufacturing a phase shift mask has the following various problems. First, a step ([step-20A]) or [step-20A] of etching the light shielding layer 22 made of chromium or the like.
B)), when the light shielding layer 22 is etched by the wet etching method, the etching proceeds isotropically, and a taper is formed on the side wall 22A of the light shielding layer 22.
Even when the light-shielding layer 22 made of chromium or the like is etched by the dry etching method, if a sufficient selection ratio cannot be obtained between the etching rate of the light-shielding layer 22 and the etching rate of the resist layer 30, the light-shielding layer 22 side walls 2
A taper is formed at 2A.

When the side wall of the light shielding layer 22 is thus tapered, there is a problem that the pattern size of the formed phase shift region 14 deviates from the design size ((D) of FIG. 16 or FIG. 18). (See the dotted line part of (D)).

[Step-40A] or [Step-
40B], when the phase shift material layer 26 or the substrate 20 is etched by using the light shielding layer 22 having such a tapered side wall as an etching mask, the pattern size of the formed light transmission region 10 becomes the design size. There is also a problem that it is displaced ((D) in FIG. 16).
Alternatively, see the dotted line portion of FIG.

Even if the pattern dimension of the light shielding layer 22 is precisely controlled in advance so that the pattern dimension of the light transmitting region 10 becomes the design dimension, the edge portion 22B of the light shielding layer 22 is extremely thin. Therefore, when the light transmissive region 10 is formed by a wet etching method, the pattern side wall of the light transmissive region 10 is not formed vertically due to isotropic etching, and in addition, the end portion 22B of the light shielding layer 22 is cleaned. In this case, there is a remarkable problem that it easily peels off and dust is generated.

When the light transmitting region 10 is formed by the dry etching method, the end portion 22B of the light shielding layer 22 recedes by the dry etching, and the light transmitting region 10 is affected by the ions and radicals generated by plasma or the like. There is also a problem that the edge portion 10A of the region 10 is sagging, or in the extreme case, the side wall of the light transmitting region 10 is not formed vertically (see (D) of FIG. 16 or (D) of FIG. 18).

Light transmitting region 1 whose side wall is not perpendicular to the substrate surface
When the exposure is performed using a phase shift mask in which 0 is formed or a phase shift mask in which the edge portion 10A of the light transmission region 10 has a sag, the light interference effect is reduced, and the pattern formed in the phase shift mask is reduced. However, there is a significant problem that it cannot be accurately transferred to the resist material formed on the wafer.

Therefore, it is an object of the present invention to provide a method of manufacturing a phase shift mask including a halftone type phase shift mask, which is capable of accurately forming a light transmitting region and a phase shift region in a desired pattern shape. It is in.

[0021]

A method of manufacturing a phase shift mask according to a first aspect of the present invention for achieving the above object is as follows: (a) a phase shift material layer, a light shielding layer,
And a step of sequentially forming a silicon dioxide layer, (b) a step of dry-etching the silicon dioxide layer into a desired pattern shape, and (c) a step of dry-etching the light-shielding layer using the silicon dioxide layer as an etching mask. And (d) dry etching the phase shift material layer using the light shielding layer as an etching mask.

Second aspect of the present invention for achieving the above object
The manufacturing method of the phase shift mask according to the aspect of, (a) a step of sequentially forming a light shielding layer and a silicon dioxide layer on the substrate surface, (b) a step of dry etching the silicon dioxide layer into a desired pattern shape, (C) a step of dry-etching the light-shielding layer using the silicon dioxide layer as an etching mask; and (d) a step of dry-etching the substrate using the light-shielding layer as an etching mask.

The amplitude transmittance of the light-shielding layer used is 0% or more and 55% or less. In the present specification, the term light-shielding layer also includes a so-called semi-light-shielding layer that slightly transmits light.

Further, in the present specification, the "phase shift region" means a region in which the exposure light is transmitted by making the phase of the light different from the region (for example, the light transmission region) of interest in the phase shift mask. , The region defined by the relative phase difference relationship with the region of interest. Further, when a transfer pattern shape or the like is formed on a resist material formed on a wafer by exposure light, one used for reduction projection is called a reticle, one used for one-to-one projection is called a mask, or The original corresponding to the master may be referred to as a reticle, and a copy thereof may be referred to as a mask. In this specification, the reticle and the mask having various meanings are collectively referred to as a mask.

[0025]

In the present invention, unlike the conventional technique, the light shielding layer is dry-etched using the silicon dioxide layer as an etching mask. It is possible to select conditions under which the light-shielding layer can be dry-etched and the silicon dioxide layer is not etched. Therefore, the side wall of the light-shielding layer that has been dry-etched can be surely made vertical.

In the present invention, the light-shielding layer is used as an etching mask to dry-etch the phase shift material layer or the substrate. It is possible to select conditions under which the phase shift material layer or the substrate can be dry-etched and the light-shielding layer is not etched. Since the side wall of the light-shielding layer is surely formed vertically, the side wall of the patterned phase shift material layer or the substrate obtained after dry etching is also surely vertical.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on embodiments with reference to the drawings. The first to fourth embodiments are the first embodiment of the present invention.
And a method of manufacturing a phase shift mask according to the above aspect. In addition, Examples 5 to 8 relate to a method of manufacturing the phase shift mask according to the second aspect of the present invention. In the drawings, the same reference numerals mean the same elements.

Example 1 Example 1 relates to a method for manufacturing a phase shift mask according to the first aspect of the present invention, and more specifically to a method for manufacturing a Levenson type phase shift mask. A schematic cross section of the phase shift mask of Example 1 is shown in FIG. The phase shift mask of Example 1 is composed of a light transmission region 10, a light shielding region 12, and a phase shift region 14. In the phase shift mask of Example 1, the respective regions are arranged such as the light blocking region 12, the phase shift region 14, the light blocking region 12, the light transmitting region 10, the light blocking region 12 ...

The light-shielding region 12 is composed of the phase shift material layer 26 formed on the substrate 20 and the light-shielding layer 2 formed thereon.
It consists of two. A silicon dioxide layer 24 is present on a part of the light shielding layer 22. Phase shift area 14
Is composed of a phase shift material layer 26 made of SOG formed on the substrate 20, for example. The thickness d of the phase shift material layer is a value that satisfies d = λ / (2 (n-1)). Here, λ is the wavelength of the exposure light, and n is the refractive index of SOG. By setting the thickness d of the phase shift material layer to such a value, the phases of the light transmitted through the light transmission region 10 and the light transmitted through the phase shift region 14 are changed by 180 degrees.

Hereinafter, a method of manufacturing the Levenson-type phase shift mask of Example 1 will be described with reference to FIGS. In each of the following examples, a positive type resist was used as the resist. The dry etching method was used for all etching steps.

[Step-100] The phase shift material layer 26, the light shielding layer 22, and the silicon dioxide layer 2 are formed on the surface of the substrate 20.
4 are sequentially formed. For this purpose, first, the phase shift material layer 26 made of, for example, SOG is formed on the transparent substrate 20 made of, for example, quartz by a spin coating method. The thickness d of the phase shift material layer 26 is set to d = λ / (2 (n-1)) so that a phase difference of 180 degrees can be realized. Then
A light shielding layer 22 made of, for example, chromium is formed on the phase shift material layer 26 by a sputtering method, and a silicon dioxide layer 24 made of, for example, SOG is applied on the light shielding layer 22. Further thereon, a resist layer 3 which is sensitive to electron beams
0 is formed (see FIG. 1A). Since the silicon dioxide layer 24 is not etched in the subsequent dry etching step of the light shielding layer 22 (see [Step-130]), it can be formed thin enough to prevent defects during the formation of the silicon dioxide layer 24. In Example 1,
The film thickness of the silicon dioxide layer 24 was set to 50 nm.

[Step-110] Next, the silicon dioxide layer 24 is dry-etched into a desired pattern shape. Therefore, drawing is performed by an electron beam with an acceleration voltage of 20 kV from a drawing device, and then the resist layer 30 is developed (see FIG. 1B). A light shielding region is formed in a region where the resist layer 30 remains in a later step. The thickness of the resist layer 30 after development was 400 nm.

[Step-120] Then, the resist layer 30
With the mask as a mask, the silicon dioxide layer 24 is dry-etched by a reactive ion etching method in plasma with a mixed gas of carbon tetrafluoride and oxygen to form a desired pattern shape (see FIG. 1C). . The etching rate of the resist layer 30 in plasma with a mixed gas of carbon tetrafluoride and oxygen was about 150 nm per minute.
On the other hand, the etching rate of the silicon dioxide layer 24 was about 60 nm / min. Therefore, the etching time required to etch the silicon dioxide layer 24 having a thickness of 50 nm is about 50 seconds, and the resist layer 30 has about 1 second.
The resist layer 30 etched by 25 nm had a thickness of about 275 nm. The thickness of the remaining resist layer 30 is
The thickness is approximately the same as the thickness of the resist layer remaining after etching the light shielding layer 22 made of chromium. Therefore, the resolution and sensitivity of the resist layer 30 similar to those in the conventional phase shift mask manufacturing method could be obtained.

[Step-130] Next, the light shielding layer 22 is dry-etched using the patterned silicon dioxide layer 24 as an etching mask. That is, after removing the resist layer 30, with a mixed gas of chlorine and oxygen,
The light shielding layer 22 made of chromium was dry-etched to obtain the structure shown in FIG. A light transmission region and a phase shift region are formed in a region where the light shielding layer 22 is removed in a later process.

The etching rate of the light-shielding layer 22 made of chromium in plasma with a mixed gas of chlorine and oxygen is about 30 nm / min. On the other hand, the silicon dioxide layer 2
Since No. 4 was not etched under the etching conditions of the light-shielding layer 22, deterioration of the pattern shape of the silicon dioxide layer 24 due to dry etching was not recognized. Therefore, when the light-shielding layer 22 was dry-etched using the silicon dioxide layer 24 as an etching mask, the sidewall of the patterned light-shielding layer 22 could be reliably formed vertically.

[Step-140] Next, a resist layer 32 which is exposed to an electron beam is formed, and an antistatic layer 34 for preventing charge-up is further applied thereon (see FIG. 2A). . Then, the accelerating voltage 20
Drawing is performed with an electron beam of kV to develop the resist layer 32 (see FIG. 2B). The area where the phase shift area is to be formed and a part of the area where the light shielding area is to be formed are
It is covered with a resist layer 32.

[Step-150] Next, the phase shift material layer 26 is dry-etched using the light-shielding layer 22 as an etching mask. That is, the phase shift material layer 26 made of SOG is dry-etched in the plasma of methane trifluoride, thereby forming the light transmission region 10 (see FIG. 2C). The silicon dioxide layer 24 not covered with the resist layer 32 is also dry-etched and removed. The etching rate of the phase shift material layer 26 with methane trifluoride was about 60 nm per minute, while the light shielding layer 22 made of chromium was not etched under the etching conditions of the phase shift material layer 26. Therefore, the side wall of the phase shift material layer 26 could be surely formed vertically. Finally, the resist layer 32
Was peeled off to obtain a Levenson type phase shift mask having a structure shown in FIG. In this phase shift mask, a part of the silicon dioxide layer 24 remains, but since it exists on the light shielding layer 22, it does not impair the performance as a phase shift mask.

Example 2 Example 2 also relates to a method of manufacturing a phase shift mask according to the first aspect of the present invention, and more specifically to a method of manufacturing an auxiliary pattern type phase shift mask. A schematic cross section of the phase shift mask of Example 2 is shown in FIG. The phase shift mask of Example 2 is also composed of the light transmission region 10, the light shielding region 12, and the phase shift region 14. The structure itself of each of these regions can be the same as that of the phase shift mask described in the first embodiment. However, a narrow light shielding region 12A exists between the light transmitting region 10 and the phase shift region 14.

A method of manufacturing the auxiliary pattern type phase shift mask of the second embodiment will be described below with reference to FIGS.

[Step-200] First, on the transparent substrate 20 made of, for example, quartz, as in the case of [Step-100] of the first embodiment, the phase shift material layer 2 made of SOG and having the thickness d is formed.
6, light-shielding layer 22 made of chromium, made of SOG, thickness 5
A 0 nm silicon dioxide layer 24 and a resist layer 30 are formed (see FIG. 3A).

[Step-210] Next, as in the case of [Step-110] in Example 1, the acceleration voltage from the drawing apparatus was 20 kV.
Is drawn by the electron beam, and then the resist layer 30 is developed (see FIG. 3B). Resist layer 3
A light shielding region is formed in a region where 0 is left in a later step. The thickness of the resist layer 30 after development was 400 nm.

[Step-220] Next, as in [Step-120] of Example 1, the resist layer 30 was used as a mask.
The silicon dioxide layer 24 is etched using reactive ion etching in plasma with a mixed gas of carbon tetrafluoride and oxygen (see FIG. 3C).

[Step-230] Next, after removing the resist layer 30, the silicon dioxide layer 24 is used as an etching mask in the same manner as in [Step-130] of Example 1.
Light-shielding layer 2 made of chromium with a mixed gas of chlorine and oxygen
2 was dry-etched to obtain the structure shown in FIG. A light transmission region and a phase shift region are formed in a region where the light shielding layer 22 is removed in a later process.

[Step-240] Next, as in [Step-140] of Example 1, a resist layer 32 is formed, and an antistatic layer 34 for preventing charge-up is further formed thereon.
Is applied (see FIG. 4A). Next, a drawing device is used to draw with an electron beam with an accelerating voltage of 20 kV,
The resist layer 32 is developed (see FIG. 4B). Most of the region where the phase shift region is to be formed and the region where the light shielding region is to be formed are covered with the resist layer 32.

[Step-250] Then, in the same manner as in [Step-150] of Example 1, using the light-shielding layer 22 as an etching mask, in plasma of methane trifluoride,
The phase shift material layer 26 made of SOG is dry-etched to form the light transmission region 10 (see FIG. 4C). The silicon dioxide layer 24 not covered with the resist layer 32 is also dry-etched and removed. Finally, the resist layer 32 was peeled off to obtain an auxiliary pattern type phase shift mask having a structure shown in FIG. Although a part of the silicon dioxide layer 24 remains in this phase shift mask, the light shielding layer 2
It does not impair the performance as a phase shift mask in any way because it exists above the No. 2.

Example 3 Example 3 also relates to a method of manufacturing a phase shift mask according to the first aspect of the present invention, and more specifically to a method of manufacturing a rim type phase shift mask. A schematic cross section of the phase shift mask of Example 3 is shown in FIG.
(D). The phase shift mask of Example 3 is also composed of the light transmission region 10, the light shielding region 12, and the phase shift region 14. The structure itself of each of these regions can be the same as that of the phase shift mask described in the first embodiment. However, the phase shift region 14 exists between the light transmitting region 10 and the light shielding region 12.

Hereinafter, a method of manufacturing the rim type phase shift mask of Example 3 will be described with reference to FIGS.

[Step-300] First, the phase shift material layer 2 made of SOG and having a thickness d is formed on the transparent substrate 20 made of, for example, quartz, as in [Step-100] of the first embodiment.
6, light-shielding layer 22 made of chromium, made of SOG, thickness 5
A 0 nm silicon dioxide layer 24 and a resist layer 30 are formed (see FIG. 5A).

[Step-310] Next, as in the case of [Step-110] in Example 1, the acceleration voltage from the drawing apparatus was 20 kV.
Is drawn by the electron beam, and then the resist layer 30 is developed (see FIG. 5B). Resist layer 3
A light shielding region is formed in a region where 0 is left in a later step.

[Step-320] Next, as in [Step-120] of the first embodiment, the resist layer 30 is used as a mask.
The silicon dioxide layer 24 is etched by reactive ion etching in plasma with a mixed gas of carbon tetrafluoride and oxygen (see FIG. 5C).

[Step-330] Next, after removing the resist layer 30, using the silicon dioxide layer 24 as an etching mask in the same manner as in [Step-130] of Example 1.
Light-shielding layer 2 made of chromium with a mixed gas of chlorine and oxygen
2 was dry-etched to obtain the structure shown in FIG. A light transmission region is formed in a region where the light shielding layer 22 is removed in a later step.

[Step-340] Then, using the light shielding layer 22 as an etching mask, the phase shift material layer 26 is etched by reactive ion etching in plasma with a mixed gas of carbon tetrafluoride and oxygen (see FIG. 6 (A)). At this time, at the same time, the silicon dioxide layer 24
Is also etched away. The etching rate of the phase shift material layer 26 by the mixed gas of carbon tetrafluoride and oxygen is about 60 nm per minute, while the light shielding layer 22 made of chromium is not etched under the etching conditions of the phase shift material layer 26. Therefore, the side wall of the phase shift material layer 26 could be surely formed vertically.

[Step-350] Next, as in [Step-140] of Example 1, a resist layer 32 is formed, and an antistatic layer 34 for preventing charge-up is further formed thereon.
Is applied (see FIG. 6B). Next, a drawing device is used to draw with an electron beam with an accelerating voltage of 20 kV,
The resist layer 32 is developed (see FIG. 6C). The region except the region where the phase shift region is to be formed is covered with the resist layer 32.

[Step-360] Then, the light shielding layer 22 made of chromium is dry-etched with a mixed gas of chlorine and oxygen, and the resist layer 32 is removed, whereby the rim-type phase shown in FIG. I got a shift mask.

Example 4 Example 4 also relates to a method of manufacturing a phase shift mask according to the first aspect of the present invention, and more specifically to a method of manufacturing a halftone phase shift mask. A schematic cross section of the halftone phase shift mask of Example 4 is shown in FIG. The halftone phase shift mask of the fourth embodiment includes the light transmission region 10
And a semi-shielded region 16.

The semi-light-shielding region 16 is composed of a phase shift material layer 26 and a semi-light-shielding layer 28 formed on the substrate 20. The semi-light-shielding layer 28 is made of chromium, for example. The difference from the light shielding layer 22 in Examples 1 to 3 lies in the thickness of chromium. The thickness of the semi-shield layer 28 is smaller than the thickness of the shield layer 22. The thickness of the semi-shielding layer 28 is set so that the amplitude transmittance of the semi-shielding region 16 is about 4% to about 55%.
Further, the phase of the light transmitted through the light transmission region 10 and the phase of the light transmitted through the semi-shielded region 16 are deviated by 180 degrees due to the existence of the phase shift material layer 26 having the thickness d. The semi-light-shielding layer 28 is also included in the term light-shielding layer in the present invention.

Hereinafter, a method of manufacturing the halftone phase shift mask of Example 4 will be described with reference to FIGS.

[Step-400] First, on the transparent substrate 20 made of, for example, quartz, as in the case of [Step-100] of the first embodiment, the phase shift material layer 2 made of SOG and having the thickness d.
6. A semi-light-shielding layer 28 made of chromium, a silicon dioxide layer 24 made of SOG and having a thickness of 50 nm, and a resist layer 30 are formed (see FIG. 7A).

[Step-410] Next, as in the case of [Step-110] in Example 1, the acceleration voltage from the drawing apparatus was 20 kV.
Is drawn by the electron beam, and then the resist layer 30 is developed (see FIG. 7B). Resist layer 3
A semi-shielded region is formed in a region where 0 remains in a later step. The thickness of the resist layer 30 after development was 400 nm.

[Step-420] Next, as in [Step-120] of Example 1, the resist layer 30 was used as a mask.
The silicon dioxide layer 24 is etched using reactive ion etching in plasma with a mixed gas of carbon tetrafluoride and oxygen (see FIG. 7C).

[Step-430] Next, after removing the resist layer 30, using the silicon dioxide layer 24 as an etching mask in the same manner as in [Step-130] of Example 1.
The semi-light-shielding layer 28 made of chromium was dry-etched with a mixed gas of chlorine and oxygen to obtain a structure shown in FIG. A light transmission region is formed in a region where the semi-shield layer 28 is removed in a later step.

[Step-440] Next, using the semi-light-shielding layer 28 as an etching mask, the phase shift material layer 26 made of SOG is formed in a plasma of methane trifluoride.
Is dry-etched to form a light transmitting region. At this time, the silicon dioxide layer 24 is simultaneously etched and removed. Thus, a halftone phase shift mask having the structure shown in FIG. 7E was obtained.

Example 5 Example 5 relates to a method of manufacturing a phase shift mask according to the second aspect of the present invention, and more specifically to a method of manufacturing a Levenson type phase shift mask. A schematic cross section of the phase shift mask of Example 5 is shown in FIG. The phase shift mask of Example 5 is composed of a light transmission region 10, a light shielding region 12, and a phase shift region 14. In the phase shift mask of Example 5, the respective regions are arranged such as the light blocking region 12, the phase shift region 14, the light blocking region 12, the light transmitting region 10, the light blocking region 12 ... The phase shift mask of Example 5 is different from the phase shift mask of Example 1 in that no phase shift material layer is present and that the light transmission region 10 is composed of a recess 20A formed in the substrate 20. . By forming such a light transmission region 10, it is possible to change the phase of the light transmitted through the phase shift region 14 and the phase of the light transmitted through the light transmission region 10.

The light shielding area 12 is composed of a light shielding layer 22 formed on the substrate 20. A silicon dioxide layer 24 is present on a part of the light shielding layer 22. The light shielding layer 22 is not formed in the phase shift region 14, and the substrate 20
Is exposed. The light transmitting region 10 is composed of a recess 20A formed in the substrate 20. The depth d ′ of the recess 20A is a value that satisfies d ′ = λ / (2 (n′−1)). Here, λ is the wavelength of the exposure light, and n ′ is the refractive index of the substrate 20. By setting the depth d ′ of the recess 20A formed in the substrate 20 to such a value, the phase of the light transmitted through the light transmission region 10 and the light transmitted through the phase shift region 14 are changed by 180 degrees.

Hereinafter, a method of manufacturing the Levenson-type phase shift mask of Example 5 will be described with reference to FIGS. Incidentally, the dry etching method was adopted for all the etching steps.

[Step-500] The light-shielding layer 22 and the silicon dioxide layer 24 are sequentially formed on the surface of the substrate 20. Therefore, first, a light shielding layer 22 made of, for example, chromium is formed on the transparent substrate 20 made of, for example, quartz by a sputtering method, and a silicon dioxide layer 24 made of, for example, SOG is applied on the light shielding layer 22. . Further, a resist layer 30 which is exposed to an electron beam is formed thereon (see FIG. 8A). The silicon dioxide layer 24 is used as the light shielding layer 2 later.
In the dry etching step 2 (see [Step-530]), the silicon dioxide layer 2 is not etched.
4 can be formed so thin that defects do not occur. In Example 5, the film thickness of the silicon dioxide layer 24 was set to 50 nm.

[Step-510] Next, the silicon dioxide layer 24 is dry-etched into a desired pattern shape. Therefore, writing is performed by an electron beam with an accelerating voltage of 20 kV from a drawing device, and then the resist layer 30 is developed (see FIG. 8B). A light shielding region is formed in a region where the resist layer 30 remains in a later step. The thickness of the resist layer 30 after development was 400 nm.

[Step-520] And the resist layer 30
With the mask as a mask, the silicon dioxide layer 24 is dry-etched by a reactive ion etching method in plasma with a mixed gas of carbon tetrafluoride and oxygen to form a desired pattern shape (see FIG. 8C). . The etching rate of the resist layer 30 in plasma with a mixed gas of carbon tetrafluoride and oxygen was about 150 nm per minute.
On the other hand, the etching rate of the silicon dioxide layer 24 was about 60 nm / min. Therefore, the etching time required to etch the silicon dioxide layer 24 having a thickness of 50 nm is about 50 seconds, and the resist layer 30 has about 1 second.
The resist layer 30 etched by 25 nm had a thickness of about 275 nm. The thickness of the remaining resist layer 30 is
The thickness is approximately the same as the thickness of the resist layer remaining after etching the light shielding layer 22 made of chromium. Therefore, the resolution and sensitivity of the resist layer 30 similar to those in the conventional phase shift mask manufacturing method could be obtained.

[Step-530] Then, the light shielding layer 22 is dry-etched using the patterned silicon dioxide layer 24 as an etching mask. That is, after removing the resist layer 30, with a mixed gas of chlorine and oxygen,
The light shielding layer 22 made of chromium was dry-etched to obtain the structure shown in FIG. In the region where the light shielding layer 22 is removed and the substrate 20 is exposed, a light transmission region and a phase shift region are formed in a later process.

The etching rate of the light-shielding layer 22 made of chromium in plasma with a mixed gas of chlorine and oxygen is about 30 nm per minute. On the other hand, the silicon dioxide layer 2
Since No. 4 was not etched under the etching conditions of the light-shielding layer 22, deterioration of the pattern shape of the silicon dioxide layer 24 due to dry etching was not recognized. Therefore, when the light-shielding layer 22 was dry-etched using the silicon dioxide layer 24 as an etching mask, the sidewall of the patterned light-shielding layer 22 could be reliably formed vertically.

[Step-540] Next, a resist layer 32 which is exposed to an electron beam is formed, and an antistatic layer 34 for preventing charge-up is further applied thereon (see FIG. 9A). . Then, the accelerating voltage 20
Drawing is performed with an electron beam of kV to develop the resist layer 32 (see FIG. 9B). The area where the phase shift area is to be formed and a part of the area where the light shielding area is to be formed are
It is covered with a resist layer 32.

[Step-550] Then, the substrate 20 is dry-etched using the light-shielding layer 22 as an etching mask to form a recess 20A in the substrate 20. That is, the substrate 20 is dry-etched in the plasma of methane trifluoride to form a recess, thereby forming the light transmission region 10 (see FIG. 9C). The silicon dioxide layer 24 not covered with the resist layer 32 is also dry-etched and removed. The etching rate of the substrate 10 with methane trifluoride was about 30 nm per minute, while the light shielding layer 22 made of chromium was not etched under the etching conditions of the substrate 20. Therefore, the side wall of the concave portion 20A of the substrate 20 could be reliably formed vertically. Finally, the resist layer 32 was peeled off to obtain a Levenson-type phase shift mask having the structure shown in FIG. Although a part of the silicon dioxide layer 24 remains in this phase shift mask, the light shielding layer 22
It does not impair the performance as a phase shift mask at all because it exists above the above.

Example 6 Example 6 also relates to a method of manufacturing a phase shift mask according to the second aspect of the present invention, and more specifically to a method of manufacturing an auxiliary pattern type phase shift mask. A schematic cross section of the phase shift mask of Example 6 is shown in FIG. The phase shift mask of Example 6 also includes the light transmission region 10, the light shielding region 12, and the phase shift region 14. The structure itself of each of these regions can be the same as that of the phase shift mask described in the fifth embodiment. However, a narrow light shielding region 12A exists between the light transmitting region 10 and the phase shift region 14.
The phase shift mask of Example 6 is different from the phase shift mask of Example 2 in that no phase shift material layer is present, and that the light transmission region 10 is composed of a recess 20A formed in the substrate 20. .

Hereinafter, a method of manufacturing the auxiliary pattern type phase shift mask of Example 6 will be described with reference to FIGS.

[Step-600] First, on the transparent substrate 20 made of, for example, quartz, as in the case of [Step-500] of the fifth embodiment, the light-shielding layer 22 made of chromium and SOG made of SOG and having a thickness of 50 nm are formed. The layer 24 and the resist layer 30 are formed (see FIG. 10A).

[Step-610] Next, in the same manner as in [Step-510] of Example 5, the acceleration voltage from the drawing apparatus was 20 kV.
Is drawn by the electron beam, and then the resist layer 30 is developed (see FIG. 10B). A light shielding region is formed in a region where the resist layer 30 remains in a later step. The thickness of the resist layer 30 after development was 400 nm.

[Step-620] Next, as in [Step-520] of Example 5, the resist layer 30 was used as a mask.
The silicon dioxide layer 24 is etched by reactive ion etching in plasma with a mixed gas of carbon tetrafluoride and oxygen (see FIG. 10C).

[Step-630] Next, after removing the resist layer 30, the silicon dioxide layer 24 is used as an etching mask in the same manner as in [Step-530] of Example 5.
Light-shielding layer 2 made of chromium with a mixed gas of chlorine and oxygen
2 was dry-etched to obtain the structure shown in FIG. In the region where the light shielding layer 22 is removed and the substrate 20 is exposed, a light transmission region and a phase shift region are formed in a later process.

[Step-640] Next, as in [Step-540] of Example 5, a resist layer 32 is formed, and an antistatic layer 34 for preventing charge-up is further formed thereon.
Is applied (see FIG. 11A). Next, writing is performed with an electron beam having an accelerating voltage of 20 kV using a writing device to develop the resist layer 32 (see FIG. 11B). Most of the region where the phase shift region is to be formed and the region where the light shielding region is to be formed are covered with the resist layer 32.

[Step-650] Next, in the same manner as in [Step-550] of Example 5, using the light-shielding layer 22 as an etching mask, in plasma of methane trifluoride,
The substrate 20 is dry-etched to form the recess 20A,
This forms the light transmission region 10 (see FIG. 11C). The silicon dioxide layer 24 not covered with the resist layer 32 is also dry-etched and removed. Finally, the resist layer 32 was peeled off to obtain an auxiliary pattern type phase shift mask having a structure shown in FIG. Although a part of the silicon dioxide layer 24 remains in this phase shift mask, the light shielding layer 2
It does not impair the performance as a phase shift mask in any way because it exists above the No. 2.

Example 7 Example 7 also relates to a method of manufacturing a phase shift mask according to the second aspect of the present invention, and more specifically to a method of manufacturing a rim type phase shift mask. FIG. 1 shows a schematic cross section of a phase shift mask of Example 7.
3 (D). The phase shift mask of Example 7 also includes the light transmission region 10, the light shielding region 12, and the phase shift region 14. The structure of each of these areas is
It can be the same as the phase shift mask described in the fifth embodiment. However, the phase shift region 14 exists between the light transmitting region 10 and the light shielding region 12. The phase shift mask of Example 7 is different from the phase shift mask of Example 3 in that there is no phase shift material layer and that the light transmission region 10 is composed of a recess 20A formed in the substrate 20. .

Hereinafter, a method of manufacturing the rim type phase shift mask of Example 7 will be described with reference to FIGS. 12 and 13.

[Step-700] First, on the transparent substrate 20 made of, for example, quartz, as in the case of [Step-500] of Example 5, the light-shielding layer 22 made of chromium and the silicon dioxide having a thickness of 50 nm and made of SOG. The layer 24 and the resist layer 30 are formed (see FIG. 12A).

[Step-710] Next, similar to [Step-510] of the fifth embodiment, the acceleration voltage from the drawing apparatus is 20 kV.
Is drawn by the electron beam, and then the resist layer 30 is developed (see FIG. 12B). A light shielding region is formed in a region where the resist layer 30 remains in a later step.

[Step-720] Next, as in [Step-520] of Example 5, using the resist layer 30 as a mask,
The silicon dioxide layer 24 is etched by reactive ion etching in plasma with a mixed gas of carbon tetrafluoride and oxygen (see FIG. 12C).

[Step-730] Next, after removing the resist layer 30, the silicon dioxide layer 24 is used as an etching mask in the same manner as in [Step-530] of the fifth embodiment.
Light-shielding layer 2 made of chromium with a mixed gas of chlorine and oxygen
2 was dry-etched to obtain the structure shown in FIG. A light transmission region is formed in a region where the light shielding layer 22 is removed and the substrate 20 is exposed in a later step.

[Step-740] Then, using the light shielding layer 22 as an etching mask, the substrate 20 is etched by reactive ion etching in plasma with a mixed gas of carbon tetrafluoride and oxygen to form a recess 20A. (See FIG. 13A). At this time, the silicon dioxide layer 24 is simultaneously etched and removed. The etching rate of the substrate 20 by the mixed gas of carbon tetrafluoride and oxygen is about 30 nm per minute, while the light shielding layer 22 made of chromium is not etched under the etching conditions of the substrate 20. Therefore, the side wall of the recess 20A could be reliably formed vertically.

[Step-750] Next, as in [Step-540] of Example 5, a resist layer 32 is formed, and an antistatic layer 34 for preventing charge-up is further formed thereon.
Is applied (see FIG. 13B). Next, writing is performed with an electron beam having an acceleration voltage of 20 kV using a writing device to develop the resist layer 32 (see FIG. 13C). The region except the region where the phase shift region is to be formed is covered with the resist layer 32.

[Step-760] Then, the light shielding layer 22 made of chromium is dry-etched with a mixed gas of chlorine and oxygen, and the resist layer 32 is removed, whereby the rim-type phase shown in FIG. I got a shift mask.

Example 8 Example 8 also relates to a method of manufacturing a phase shift mask according to the second aspect of the present invention, and more specifically to a method of manufacturing a halftone phase shift mask. A schematic cross section of the halftone phase shift mask of Example 8 is shown in FIG. Example 8
The halftone type phase shift mask of
It is composed of 0 and semi-shielded regions 16. The halftone phase shift mask of Example 8 is different from the halftone phase shift mask of Example 4 in that there is no phase shift material layer and that the light transmission region 10 is formed in the substrate 20 in a recess. It consists of 20A.

The semi-shielded region 16 is composed of a semi-shielded layer 28 formed on the substrate 20. The semi-shielding layer 28 is
It consists of chrome, for example. The difference from the light-shielding layer 22 in Examples 5 to 7 lies in the thickness of chromium. Semi-shading layer 2
The thickness of 8 is thinner than the thickness of the light shielding layer 22. Semi-shielded area 1
The thickness of the semi-light-shielding layer 28 is set so that the amplitude transmittance of No. 6 is about 4% to about 55%. Further, the phase of the light transmitted through the light transmission region 10 and the phase of the light transmitted through the semi-shielded region 16 are deviated from each other by 180 degrees because the recess having the depth d ′ is formed in the substrate 20. The semi-light-shielding layer 28 is also included in the term light-shielding layer in the present invention.

Hereinafter, a method for manufacturing the halftone phase shift mask of Example 8 will be described with reference to FIG.

[Step-800] First, on the transparent substrate 20 made of, for example, quartz, as in the case of [Step-500] in Example 5, a semi-light-shielding layer 28 made of chromium and SOG made of SOG having a thickness of 50 nm. The silicon layer 24 and the resist layer 30 are formed (see FIG. 14A).

[Step-810] Next, as in [Step-510] of the fifth embodiment, the acceleration voltage from the drawing apparatus is 20 kV.
Is drawn by the electron beam, and then the resist layer 30 is developed (see FIG. 14B). In a region where the resist layer 30 is left, a semi-shielded region is formed in a later process. The thickness of the resist layer 30 after development was 400 nm.

[Step-820] Next, as in [Step-520] of Example 5, using the resist layer 30 as a mask,
The silicon dioxide layer 24 is etched by reactive ion etching in plasma with a mixed gas of carbon tetrafluoride and oxygen (see FIG. 14C).

[Step-830] Next, after removing the resist layer 30, using the silicon dioxide layer 24 as an etching mask in the same manner as in [Step-530] of Example 5.
The semi-light-shielding layer 28 made of chromium was dry-etched with a mixed gas of chlorine and oxygen to obtain a structure shown in FIG. A light transmission region is formed in a region where the semi-shield layer 28 is removed in a later step.

[Step-840] Next, using the semi-light-shielding layer 28 as an etching mask, the substrate 20 is dry-etched in plasma with methane trifluoride to form the recess 20A, whereby the light transmitting region 10 is formed. To form. At the same time, the silicon dioxide layer 24 is simultaneously etched and removed. Thus, a halftone phase shift mask having the structure shown in FIG. 14E was obtained.

The present invention has been described above based on the preferred embodiments, but the present invention is not limited to these embodiments. The conditions and numerical values described in the examples are examples,
It can be changed appropriately. For example, the phase and amplitude transmittance of light in each region are examples, and can be changed to optimum values as appropriate.

In each embodiment, the silicon dioxide layer 24
Although SOG is used as the material, silicon dioxide formed by a CVD method, a sputtering method, an ion plating method, or the like may be used, and the method for forming the silicon dioxide layer is not limited at all. In addition, the resist layer 3
Although a positive resist material is used as 0 and 32, a negative resist material may be used without any problem. In this case, the electron beam drawing area is different from that of the positive resist material only in that it is opposite. The material forming the phase shift material layer is not limited to SOG, but is a transparent material such as polymethylmethacrylate, magnesium fluoride, titanium dioxide, polyimide resin, silicon dioxide, indium oxide, SiN, various resists, or the like. If Further, the light shielding layer is not limited to chromium, and any material having a light shielding property such as aluminum or metal silicide can be used.

[0100]

According to the present invention, by forming the silicon dioxide layer on the light shielding layer, the patterned phase shift material layer obtained after dry etching or the side wall of the substrate can be surely made vertical, A desired pattern shape can be obtained.

In the present invention, the number of steps for forming the silicon dioxide layer on the light-shielding layer is increased as compared with the conventional method for manufacturing a phase shift mask, which reduces the productivity and the manufacturing cost in manufacturing the phase shift mask. The increase is extremely slight.

Further, according to the present invention, the controllability of the phase shift mask manufacturing process is significantly improved. Furthermore, since the light exposure can be performed by the pattern shape having the vertical side wall shape, and the interference effect of the light having different phases can be maximized, the pattern shape formed on the phase shift mask is formed on the wafer. When transferred to the formed resist, deterioration of the transferred pattern shape can be significantly reduced, patterns can be formed with a high yield, and the manufacturing cost in the production of semiconductor devices can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic partial cross-sectional view of a substrate and the like in each step for explaining a method of manufacturing a phase shift mask of Example 1.

FIG. 2 is a schematic partial cross-sectional view of the substrate and the like in each step for explaining the manufacturing method of the phase shift mask of Example 1 following FIG.

FIG. 3 is a schematic partial cross-sectional view of a substrate and the like in each step for explaining the method of manufacturing the phase shift mask of Example 2.

FIG. 4 is a schematic partial cross-sectional view of the substrate and the like in each step for explaining the manufacturing method of the phase shift mask of Example 2 subsequent to FIG.

5A and 5B are schematic partial cross-sectional views of a substrate and the like in each step for explaining the method of manufacturing the phase shift mask of Example 3.

FIG. 6 is a schematic partial cross-sectional view of the substrate and the like in each step for explaining the manufacturing method of the phase shift mask of Example 3 subsequent to FIG.

FIG. 7 is a schematic partial cross-sectional view of a substrate and the like in each step for explaining the method of manufacturing the phase shift mask of Example 4.

FIG. 8 is a schematic partial cross-sectional view of a substrate and the like in each step for explaining the method of manufacturing the phase shift mask of Example 5.

FIG. 9 is a schematic partial cross-sectional view of the substrate and the like in each step for explaining the manufacturing method of the phase shift mask of Example 5 subsequent to FIG.

FIG. 10 is a schematic partial cross-sectional view of the substrate and the like in each step for explaining the method of manufacturing the phase shift mask of Example 6.

11 is a schematic partial cross-sectional view of the substrate and the like in each step for explaining the manufacturing method of the phase shift mask of Example 6 subsequent to FIG.

FIG. 12 is a schematic partial cross-sectional view of the substrate and the like in each step for explaining the method for manufacturing the phase shift mask of Example 7.

FIG. 13 is a schematic partial cross-sectional view of the substrate and the like in each step for explaining the manufacturing method of the phase shift mask of Example 7 subsequent to FIG.

FIG. 14 is a schematic partial cross-sectional view of the substrate and the like in each step for explaining the method of manufacturing the phase shift mask of Example 8.

FIG. 15 is a schematic partial cross-sectional view of a substrate and the like in each step for explaining a conventional method for manufacturing a phase shift mask.

FIG. 16 is a schematic partial cross-sectional view of the substrate and the like in each step for explaining the conventional method for manufacturing the phase shift mask, following FIG. 15.

FIG. 17 is a schematic partial cross-sectional view of a substrate and the like in each step for explaining a conventional method for manufacturing a phase shift mask of another type.

FIG. 18 is a schematic partial cross-sectional view of the substrate or the like in each step for explaining the conventional method for manufacturing the phase shift mask, continuing from FIG. 17;

[Explanation of symbols]

 10 Light Transmission Area 12 Light-shielding Area 14 Phase Shift Area 16 Semi-light-shielding Area 20 Substrate 22 Light-shielding Layer 24 Silicon Dioxide Layer 26 Phase-shifting Material Layer 28 Semi-light-shielding Layer 30, 32 Resist Layer 34 Antistatic Layer

Claims (2)

[Claims] 1. (a) A step of sequentially forming a phase shift material layer, a light-shielding layer, and a silicon dioxide layer on a substrate surface, and (b) a step of dry etching the silicon dioxide layer into a desired pattern shape. (C) a step of dry-etching the light-shielding layer using the silicon dioxide layer as an etching mask, and (d) a step of dry-etching the phase shift material layer using the light-shielding layer as an etching mask. Of manufacturing a phase shift mask. 2. (a) a step of sequentially forming a light-shielding layer and a silicon dioxide layer on the surface of the substrate; (b) a step of dry etching the silicon dioxide layer into a desired pattern shape; and (c) the silicon dioxide. A method of manufacturing a phase shift mask, comprising: a step of dry-etching the light-shielding layer using the layer as an etching mask; and (d) a step of dry-etching the substrate using the light-shielding layer as an etching mask.