JPH11327121A - Method for manufacturing halftone type phase shift mask and blank of halftone type phase shift mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a mask enabling shortening of the time needed for the acceptance of an order through the completion of a product and inspecting of a mask blank as it is before the completion of a mask product and a blank necessary for this. SOLUTION: This method comprises of the steps of: depositing successively a semi-transparent phase shift layer 4, a light shielding layer 5, a first resist layer 6; forming a first resist film by patterning only a peripheral portion outside an effective area into a predetermined shape; forming a light-shielding film 5' by patterning the light-shielding layer through etching; peeling off the first resist film 6'; examining the semi-transparent phase shift layer exposed in the effective area; depositing a second resist layer 7 on a structure thus formed; forming a second resist film 7' whose shape corresponds to a shape of a main pattern; forming a semi-transparent phase shift film 4' by patterning the semi-transparent phase shift layer by etching; and peeling off the second resist film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photomask having a pattern mainly used in a projection exposure apparatus, and more particularly to a high resolution pattern provided by giving a phase difference to projection exposure light passing through the photomask. TECHNICAL FIELD The present invention relates to a method for manufacturing a phase shift mask capable of transferring an image and a blank used in the method.

[0002]

2. Description of the Related Art Various types of phase shift masks have been proposed. For example, a Levenson-type phase shift mask having a structure in which a transparent film is provided so as to invert the phase on one side adjacent to the opening on the mask, or a phase shifter having a resolution equal to or less than the resolution limit is formed around the pattern to be formed. Phase shift mask with auxiliary pattern of structure,
There is a self-aligned phase shift mask having a structure in which a phase shifter overhang is formed by overetching after forming a chromium pattern on a substrate.

The phase shift mask of each of the above structures is provided with a chromium pattern and a shifter pattern on a substrate. Apart from this structure, a phase shift mask formed of only a shifter pattern is used as a transmission type phase shift mask. Shift masks and halftone phase shift masks are also known. A transmissive phase shift mask is a phase shift mask that separates patterns by utilizing the fact that light intensity becomes zero at a boundary between light transmitted through a transparent part and light transmitted through a phase shifter. Therefore, it is also called a shifter edge-based phase shift mask. Also,
A halftone type phase shift mask is formed by forming a so-called semi-transparent phase shifter pattern on a substrate, which has partial transparency to projection exposure light, and forms a light intensity formed at a boundary portion of the phase shifter pattern. Is a phase shift mask in which the pattern resolution is improved in a portion where is zero. Since the transmission type phase shift mask and the halftone type phase shift mask have a simple layer structure, the manufacturing steps are easy and the defects on the mask are few. The halftone type phase shift mask is formed, for example, by laminating a translucent phase shift film 12a on a transparent substrate 11, as shown in FIG.
As shown in FIG. 6, an effective area 13 is formed on a transparent substrate 11 surrounded by a translucent phase shift film 12a. Then, a desired pattern, in this example, the character “A” is formed inside the effective area 13. actually,
An IC chip pattern is formed in this effective area.

Now, consider a case where a pattern is transferred by a stepper to a resist provided on the surface of a silicon wafer using such a halftone type phase shift mask. In this case, as shown in FIG. 6, the periphery of the effective area 13 is surrounded by an aperture 14, and as shown in FIG. 4, the light R passing through the effective area 13 is irradiated onto the wafer 15 through a lens. Usually, for example, a 1/5 reduced image is formed on the wafer 15. At this time, the aperture 14 surrounding the effective area 13 acts to prevent light from shining on an area other than the predetermined exposure area of the wafer 15. However, since a gap of 1 to 2 mm is formed in the lateral direction between the outer peripheral edge of the effective area 13 and the inner peripheral edge of the aperture 14, the semi-transparent phase shift film 12a located on the outer peripheral edge of the effective area 13 The hit light is reflected by the phase shift film 12a.
Of light corresponding to the inherent light transmittance of the light. Therefore, in FIG. 4, for example, when a large number of transfer images are sequentially formed on the wafer 15 by shifting the irradiation position of the exposure light as shown by an arrow A, as shown in FIG. Are exposed twice, or a small square portion Q surrounded by four effective areas 13 is exposed four times.

The outer peripheral portion of the effective region 13 is a portion where the resist should not be exposed to light. Therefore, the semi-transparent phase shift film 12a is provided in that portion. If the resist is heavily exposed or quadruple exposed, the resist is exposed to light, and there is a problem that a pattern that should not exist is formed in that area.

In order to solve such a problem, in a halftone type phase shift mask formed by laminating a translucent phase shift film on a transparent substrate, the translucent phase shift film is formed into a predetermined pattern in an effective area. There is proposed a halftone type phase shift mask having a configuration in which a light shielding film is provided on a translucent phase shift film formed on an outer peripheral portion outside an effective area (Japanese Patent Application No. 7-160100). ). The manufacturing method is shown in FIG. (1) A translucent phase shift layer, a light shielding layer, a first
A step of sequentially stacking resist layers; (FIG. 3A) (2) A step of patterning the first resist layer into a predetermined shape to form a first resist film having a predetermined shape.・ ・
FIGS. 3B and 3C (3) a step of forming a light shielding film by patterning the light shielding layer by etching using the patterned first resist film as a mask. (FIG. 3D) (4) A step of forming a translucent phase shift film by patterning the translucent phase shift layer by etching using the patterned first resist film as a mask. ... Figure 3
(E) (5) removing the first resist film; ... Figure 3
(F) (6) A step of laminating a second resist layer. ... Figure 3
(G) (7) a step of patterning the second resist layer in the effective area into a predetermined shape to form a second resist film. ...
FIG. 3 (h) (i) (8) A step of forming a light-shielding film by patterning the light-shielding layer by etching using the patterned second resist film as a mask. .. FIG. 3 (j) (9) Step of stripping the second resist film. ... Figure 3
(K)

However, when the halftone type phase shift mask having the above structure is manufactured as described above,
That is, a translucent phase shift layer, a light shielding layer, a first
If the steps from the blank formed by sequentially laminating the resist layers to the translucent phase shift mask as the final product are performed consistently, the following problems arise. Since the drawing is performed twice and the etching is performed three times, it takes a lot of time from receiving an order to completing the order. In the blank state, since the light-shielding layer is laminated on the translucent phase shift layer, changes occurring in the step of forming the light-shielding film for the translucent phase shift layer (FIG. 3 (j)), for example, the presence or absence of defects, The transmittance, the phase difference, and the like cannot be inspected, and as a result, these inspections have to be performed on the final product. Therefore, if a defect is found as a result of inspecting the final product, the entire manufacturing process is wasted.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has been made to reduce the time required from receipt of an order to completion of a final product,
In addition, before the final product is completed, it is possible to provide a manufacturing method capable of inspecting the presence or absence of a defect of the translucent phase shift layer in a blank state, transmittance, phase difference, and the like. It is an object to provide a blank.

[0009]

In order to achieve the above object, a first aspect of the present invention is a halftone type phase shifter comprising a translucent phase shift film and a light shielding film sequentially laminated on a transparent substrate. In the method for manufacturing a mask, (1) a step of sequentially laminating a translucent phase shift layer, a light shielding layer, and a first resist layer on a transparent substrate; and (2) a main pattern by patterning the first resist layer. Selectively leaving the first resist layer on the outer peripheral portion outside the effective region,
Forming a first resist film, (3) forming a light-shielding film by patterning the light-shielding layer by etching using the first resist film as a mask, (4) removing the first resist film, and (5). Inspecting the translucent phase shift layer exposed in the effective area, (6) laminating the second resist layer, (7) patterning the second resist layer into a predetermined shape, and Forming a second resist film corresponding to the shape of the main pattern; (8) using the second resist film as a mask, patterning the translucent phase shift layer by etching to form a translucent phase shift film having a main pattern shape; And (9) removing the second resist film.

According to a second aspect of the present invention, in the method of manufacturing a halftone type phase shift mask according to the first aspect, a step of storing between the steps (5) and (6). 2. The method of manufacturing a halftone phase shift mask according to claim 1, comprising:

According to a third aspect of the present invention, there is provided a blank for manufacturing a halftone type phase shift mask in which a translucent phase shift film and a light shielding film are sequentially laminated on a transparent substrate. A halftone phase shifter, wherein a light-shielding film is selectively provided on an outer peripheral portion outside an effective area to be formed, and the translucent phase shift layer in the effective area is unpatterned (solid). This is a shift mask blank.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to examples.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In making a mask, the following steps are generally taken. That is, before the design of the effective area serving as the pattern of the actual IC chip is completed, the size of the chip is determined, and the design of the outer peripheral portion is completed. Therefore, when ordering a mask, it is possible to order the outer periphery first and supply the effective area later (final order). An embodiment for manufacturing a mask when such an order is received will be described.

FIG. 1 shows the steps of a method for manufacturing a halftone type phase shift mask according to the present invention. After receiving the order, as shown in FIG. 1A, Mo is formed on a transparent substrate 3 formed of quartz by using a known film forming method.
Translucent phase shift layer 4 made of SiON (molybdenum oxynitride), Cr (chromium), CrO (chromium oxide), CrN (chromium nitride), CrON (chromium oxynitride), CrOCN (chromium oxycarbonitride) or Forming a light-shielding layer 5 made of a laminated or mixed material;
The first resist layer 6 was formed using a positive resist. The thickness of each layer is such that the translucent phase shift layer 4 is 1200 to 200
0 °, the light-shielding layer 5 was 300-1500 °, and the first resist layer 6 was 3000-6000 °.

Next, exposure with an electron beam (FIG. 1B)
A first resist film 6 'having a desired pattern (in this case, an outer peripheral portion) was formed by subsequent development (FIG. 1).
(C)). Further, using the first resist film 6 'as a mask, an etching solution prepared by adding ceric ammonium nitrate to perchloric acid is used, and wet etching is performed in a usual manner, or Cl ₂ (chlorine) and O ₂ (oxygen The light-shielding layer 5 was patterned into a light-shielding film 5 'having a desired pattern by dry etching using the mixed gas of (1) (FIG. 1D).

Next, first using oxygen plasma or sulfuric acid,
By stripping the resist film 6 ', a light-shielding film 5' having a predetermined shape is formed only on the outer peripheral portion outside the effective region, and the translucent phase shift layer 4 in the effective region is not patterned. 2) was obtained (FIG. 1 (e)). On the intermediate blank 2, a registration mark 9 and a registration mark 10 required for the second drawing are formed (FIG. 2). At the stage of the intermediate blank 2, the semi-transparent phase shift layer 4 in the effective area was inspected for defects, transmittance, phase difference, and the like. If a defect was found as a result of the inspection, the defect was corrected by a standard method. The intermediate blank 2 was stored until the formation of the main pattern (effective area) could be started.

After receiving the main pattern, the following steps were performed. A second resist layer 7 was formed on the light-shielding film 5 'using a positive resist (FIG. 1F). Next, a second resist film 7 'having a desired pattern (main pattern and outer peripheral portion) was formed by exposure with an electron beam (FIG. 1 (g)) and subsequent development (FIG. 1 (h)).
Further, using the second resist film 7 'as a mask, CF ₄ ,
By dry etching with a mixed gas of C ₂ F ₆ and fluorine-based gas and O ₂ (oxygen), was patterned semi-transparent phase shift layer 4 to a translucent phase shift film 4 'having a desired pattern (FIG. 1 (i)) . Next, the first resist film 7 'is stripped using oxygen plasma or sulfuric acid, so that the light-shielding film 5' having a predetermined shape is formed only on the outer peripheral portion outside the effective region, and the predetermined shape is formed in the effective region. A halftone type phase shift mask with the main pattern formed was obtained (FIG. 1 (j)).

[0018]

According to the method for manufacturing a halftone type phase shift mask of the present invention, the presence or absence of a defect in the translucent phase shift layer and the transmission of the translucent phase shift layer in a blank state where the translucent phase shift layer is exposed in the effective area Rate, phase difference, etc. can be inspected, so by performing these inspections before the final product is completed, it is possible to correct it early if a defect is found at this stage. is there. Further, since the step of receiving the main pattern after forming the intermediate blank and forming the main pattern in the effective area is performed, in the step after receiving the supply, one drawing, one time Since etching is sufficient, the time required for manufacturing from receiving an order to completing a final product can be reduced.

According to the blank for a halftone type phase shift mask of the present invention, since the translucent phase shift layer in the effective area is exposed, the presence or absence of a defect in the translucent phase shift layer in the effective area is determined. It is easy to inspect transmittance, phase difference, and the like.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a method for manufacturing a halftone type phase shift mask according to the present invention, and (a) to (j).
Is a cross-sectional view in the order of steps.

FIG. 2 is a plan view of FIG. 1E showing an embodiment of a method for manufacturing a halftone phase shift mask according to the present invention.

3A to 3K are views showing a method for manufacturing a conventional halftone type phase shift mask, in which FIGS.

FIG. 4 is a side sectional view showing an example of an exposure system using a halftone type phase shift mask.

FIG. 5 is a schematic view showing a state in which a main pattern is transferred onto an exposure target using a conventional halftone type phase shift mask.

FIG. 6 is a plan view showing a conventional halftone type phase shift mask and a state in which an aperture is put on the mask.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Halftone type phase shift mask 2 ... Intermediate blank for halftone type phase shift mask 3 ... Transparent substrate 4 ... Translucent phase shift layer 4 '... Translucent Phase shift film 5 Light-shielding layer 5 'Light-shielding film 6 First resist layer 6' First resist film 7 Second resist layer 7 ' ··· Second resist film 8 ··· Electron beam 9 ··· Positioning mark 10 ··· Superposition mark 11 ··· Transparent substrate 12a ··· Phase shift film 12b ··· Fiducial Mark 13: Effective area 14: Aperture 15: Wafer

Claims (3)

[Claims] 1. A method for manufacturing a halftone type phase shift mask in which a translucent phase shift film and a light shielding film are sequentially laminated on a transparent substrate. (2) patterning the first resist layer to selectively leave the first resist layer on the outer peripheral portion outside the effective area where the main pattern is to be present Forming a first resist film, (3) forming a light-shielding film by patterning the light-shielding layer by etching using the first resist film as a mask, (4) removing the first resist film, (5) A) inspecting the translucent phase shift layer exposed in the effective area, (6) laminating a second resist layer, and (7) patterning the second resist layer into a predetermined shape to form a pattern in the effective area. Nime Forming a second resist film corresponding to the shape of the main pattern, and (8) using the second resist film as a mask, patterning the semi-transparent phase shift layer by etching to form a semi-transparent phase shift film having a main pattern shape. And (9) a step of removing the second resist film. 2. A method for manufacturing a halftone phase shift mask according to claim 1, further comprising a step of storing between the steps (5) and (6). Item 2. A method for manufacturing a halftone phase shift mask according to Item 1. 3. A blank for manufacturing a halftone type phase shift mask in which a translucent phase shift film and a light shielding film are sequentially laminated on a transparent substrate, an outer peripheral portion outside an effective area for forming a main pattern. A semi-transparent phase shift layer in the effective area is in a non-patterned (solid) state.