TW201915596A - Photomask and method for manufacturing the photomask - Google Patents

Abstract

A method of manufacturing a photomask comprising the steps of: providing a photomask blank having a substrate, an absorber layer, a hard mask layer and a photoresist layer. The absorber layer, a hard mask layer and a photoresist layer are sequentially arranged on the substrate; patterning the photoresist layer to form a photoresist opening; patterning the hard mask layer with the photoresist layer as a mask and forming a hard mask layer opening in the hard mask layer; removing the photoresist layer and forming a polymer film which covering the surface of the hard mask layer; removing the polymer film which located on the upper surface of the hard mask layer and the upper surface of the absorbent layer; patterning the absorbent layer with a mask which combining the hard mask layer with the polymer film of the side wall of the hard mask to form an absorbent layer opening; removing the hard mask layer and the polymer film of the side wall of the hard mask.

Description

 Mask and mask manufacturing method  

The present invention relates to a photomask and a photomask manufacturing method, and more particularly to a photomask and a photomask manufacturing method for improving the verticality of a sidewall of a three-dimensional structure of a photomask pattern.

In the current optical lithography technology, Reticle's deep ultraviolet (DUV) exposure technology for the wafer photoresist layer can be mainly divided into a binary chrome film mask and a phase shift mask (Phase Shift Mask). Kind. The binary chrome film reticle mainly uses chrome and its compound as a light blocking material; and the phase shift reticle is a problem caused by reducing the diffraction phenomenon, thereby increasing the image contrast and improving the resolution. Due to the addition of the phase shifting material, the light directions of the adjacent two light-transmitting regions are opposite, causing destructive interference of the diffracted light, so that the light intensity of the opaque region is weakened, thereby enhancing the original contrast and making the original unsolvable The area becomes analyzable.

As shown in FIG. 1, in the phase shift mask optical lithography, the absorbing layer 52 and the hard mask layer 53 are sequentially disposed on the substrate 51 of the reticle M5, and the absorbing layer 52 is covered by the hard mask layer 53. When the cover is patterned, since the horizontal etching rate of the upper absorption layer 52a is greater than the horizontal etching rate of the lower absorption layer 52b, the sidewall of the absorption layer pattern 521 formed after patterning protrudes from the hard mask layer. 53 mask, and the angle between the side wall of the absorption layer pattern 521 and the upper surface of the substrate 51 at the absorption layer pattern 521 is between 83 and 85 degrees, which is limited by the fact that the absorption layer 52 cannot be over-etched for a long time. To eliminate the sidewall bevel angle at the absorbing layer pattern 521, in the process of the phase shift mask M5, the sidewall of the absorbing layer pattern 521 is difficult to reach a nearly vertical state, and the light is interfered when passing through the gap of the absorbing layer pattern 521, resulting in light intensity. Unevenness reduces the optical imaging effect, which in turn affects the resolution of wafer exposure.

In view of this, how to optimize the three-dimensional structure of the absorbing layer pattern during the patterning of the absorbing layer, improve the fidelity of the reticle pattern, and at the same time improve the light intensity and optical resolution, which is one of the important topics in the field.

In order to achieve the above object, the present invention provides a method for manufacturing a photomask, comprising the steps of: providing a photomask blank, the photomask blank having a substrate, an absorbing layer, a hard mask layer and a photoresist layer, absorbing The layer, the hard mask layer and the photoresist layer are sequentially disposed on the substrate; the photoresist layer is patterned to form a plurality of photoresist layer openings, so that the upper surface of the portion of the hard mask layer is exposed from the openings of the photoresist layers Forming the hard mask layer with the photoresist layer as a mask, forming a plurality of hard mask layer openings in the hard mask layer, and exposing the upper surface of the portion of the absorber layer from the openings of the hard mask layers; a photoresist layer, and forming a polymer film covering the upper surface of the hard mask layer, sidewalls of the hard mask layer opening and the absorber layer exposed on the upper surface of the opening of the hard mask layer; removing the hard mask The polymer film on the upper surface of the layer and the upper surface of the absorbing layer causes the polymer film to remain on the side walls of the openings of the hard mask layers; and the hard mask layer and the sidewalls remaining in the openings of the hard mask layers are high. The molecular film is a mask, and the absorption layer is patterned to form an absorption layer. Number absorbent layer having an opening, a portion of the upper surface of the substrate from the plurality of openings to expose the absorbent layer; and removing the plurality of polymer film remaining on the hard mask layer having an opening sidewall and the hard mask layer.

In one embodiment, the absorbing layer is patterned to form an absorbing layer pattern, and the absorbing layer pattern has an angle between the sidewall of the opening of the absorbing layer and the upper surface of the substrate at the absorbing layer pattern, and the angle is between 87 and 90. degree.

In one embodiment, the absorbing layer is patterned by plasma etching, and the upper surface of the hard mask layer and the upper surface of the absorbing layer are removed by plasma etching, and the plasma is oxygen. Slurry or argon plasma.

In one embodiment, the patterned horizontal etch rate of the absorbing layer located at the upper portion is similar to the patterned horizontal etch rate of the absorbing layer at the lower portion.

In one embodiment, the polymer film remaining on the sidewalls of the openings of the hard mask layers has a thickness of 1 to 20 nm.

In one embodiment, the polymer film is formed by chemical vapor deposition using methane, ethane or acetylene.

In one embodiment, the substrate is made of quartz, optical glass or sapphire.

In one embodiment, the material of the absorber layer is a molybdenum-ruthenium multilayer film or a change in substrate thickness is used to achieve phase reversal.

In one embodiment, the hard mask layer is made of chromium, chromium oxide, titanium, titanium tungsten, tungsten, tantalum nitride, hafnium oxide or titanium nitride.

In one embodiment, the material of the polymer film is a high molecular polymer.

The invention further provides a photomask comprising a substrate and an absorption layer pattern, the substrate being a flat plate structure. The absorbing layer pattern is disposed on the substrate, the absorbing layer pattern has a plurality of openings, and a portion of the upper surface of the substrate is exposed from the openings. The absorption layer pattern has an angle between the sidewall of the opening and the upper surface of the substrate at the absorption layer pattern, and the angle is between 87 and 90 degrees.

In one embodiment, the substrate is made of quartz, optical glass or sapphire.

In one embodiment, the material of the absorber layer is made of a molybdenum-ruthenium multilayer film or a change in thickness of the substrate is used to achieve phase reversal.

According to the above, the method for manufacturing the photomask and the photomask of the present invention is to deposit a polymer film on the upper surface of the hard mask layer before patterning by the absorption layer, and the hard mask layers are open. The sidewall and the absorbing layer are exposed on the upper surface of the openings of the hard mask layer, and the polymer film covering the upper surface of the hard mask layer and the absorbing layer is removed, and then the openings remaining in the hard mask layer are used. The polymer film of the sidewall competes with the adjacent absorber layer for plasma-reactive ions, and the horizontal etching rate of the absorber layer located at the upper portion is controlled to be close to the horizontal etching rate of the absorber layer at the lower portion, so that the sidewall of the absorber layer pattern is nearly vertical. Optimize the three-dimensional structure of the absorbing layer pattern to enhance the fidelity of the reticle pattern, while allowing light to pass through the gap of the absorbing layer pattern without being affected, so that the light intensity is maintained uniform, the optical imaging effect is increased, and the wafer exposure is further analyzed. degree.

1‧‧‧Photomask blank

11, 31, 51‧‧‧ substrates

12, 12a, 12b, 52, 52a, 52b‧‧ ‧ absorption layer

121‧‧‧Absorbent opening

122, 32, 32a, 32b, 521‧‧ ‧ absorption layer pattern

13, 53‧‧‧ hard mask layer

131‧‧‧hard mask opening

14‧‧‧ photoresist layer

141‧‧‧ photoresist layer opening

2, 21‧‧‧ polymer film

321‧‧‧ openings

M1, M3, M5‧‧‧ mask

S01, S02, S03, S04, S05, S06, S07‧‧ steps

θ 1, θ 3, θ 5‧‧‧ angle

1 is a partial side elevational view of a conventional reticle absorbing layer pattern without a hard mask layer removed.

2 is a flow chart of a method of manufacturing a photomask of the present invention.

3A to 3I are schematic views showing a manufacturing method of the reticle shown in Fig. 2.

4 is a partial enlarged view of the photomask and the hard mask layer shown in FIG. 3H.

Figure 5 is a side elevational view of the reticle of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method of manufacturing a reticle according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings, in which the same elements will be described with the same reference numerals.

Please refer to FIG. 2, FIG. 3A to FIG. 3I, FIG. 2 is a flowchart of a method for manufacturing a photomask according to the present invention, and FIGS. 3A to 3I are schematic diagrams showing a manufacturing method of the photomask shown in FIG.

The method for manufacturing the mask M1 of the present invention comprises the steps of: first providing a mask blank 1 and, as shown in FIG. 3A, the mask blank 1 has a substrate 11, an absorbing layer 12, and a hard mask layer. 13 and a photoresist layer 14, the absorber layer 12, the hard mask layer 13, and the photoresist layer 14 are sequentially disposed on the substrate 11 (step S01). The material of the substrate 11 is quartz, optical glass or sapphire, and the material of the absorbing layer 12 is a molybdenum-ruthenium multilayer film or a phase reversal is achieved by changing the thickness of the substrate 11, and a sputtering method is usually used to form a hard surface. The mask layer 13 covers the hard mask layer 13 over the absorbing layer 12. The hard mask layer 13 is made of chromium, chrome oxide, titanium, titanium tungsten, tungsten, tantalum nitride, cerium oxide or titanium nitride. .

As shown in FIG. 3B and FIG. 3C, the photoresist layer 14 is patterned to form a plurality of photoresist layer openings 141, and the upper surface of a portion of the hard mask layer 13 is exposed from the photoresist layer openings 141 (step S02). . Thereafter, the photoresist layer 14 is used as a mask, and the hard mask layer 13 is patterned to form a plurality of hard mask layer openings 131 in the hard mask layer 13, so that the upper surface of the portion of the absorber layer 12 is hardened. The mask layer opening 131 is exposed (step S03).

After removing the photoresist layer 14 (see FIG. 3D), as shown in FIG. 3E, chemical vapor deposition (CVD) is performed by using methane, ethane or acetylene to form a polymer film 2 covering the hard mask. The upper surface of the layer 13, the side walls of the hard mask layer openings 131, and the absorbing layer 12 are exposed on the upper surfaces of the hard mask layer openings 131 (step S04). The material of the polymer film 2 is a high molecular polymer. In addition, the thickness of the polymer film 2 can be designed to be between 1 and 20 nm as required by the process of the mask M1. After the polymer film 2 is completely covered, as shown in FIG. 3F, the polymer film 2 covering the upper surface of the hard mask layer 13 and the upper surface of the absorption layer 12 is removed, and the polymer film 21 remains therein. The side wall of the hard mask layer opening 131 (step S05). Further, in step S05, the polymer film 2 in the horizontal direction as shown in FIG. 3F is removed by plasma etching, that is, the upper surface of the hard mask layer 13 and the upper surface of the absorption layer 12 are high. The molecular film 2 is removed by plasma etching, and the plasma in the process is oxygen plasma or argon plasma. After the polymer film 2 in the horizontal direction is removed, the polymer film 21 in the vertical direction as shown in FIG. 3F remains on the side walls of the hard mask layer openings 131.

As shown in FIG. 3G, the hard mask layer 13 and the polymer film 21 remaining on the sidewalls of the hard mask layer openings 131 are masked, and the absorber layer 12 is patterned to form a plurality of absorber layers in the absorber layer 12. The opening 121 exposes the upper surface of the portion of the substrate 11 from the absorption layer openings 121 (step S06). The absorbing layer 12 is patterned by plasma etching.

Please refer to FIG. 3H and FIG. 4 simultaneously. FIG. 4 is a partial enlarged view of the mask M1 shown in FIG. 3H. The absorbing layer 12 is patterned to form an absorbing layer pattern 122. The absorbing layer pattern 122 is located at the absorbing layer openings 121. The sidewall and the upper surface of the substrate 11 have an angle θ between the absorption layer pattern 122, and the included angle θ 1 is between 87 and 90 degrees. Further, in step S06, the polymer film 21 remaining on the side walls of the hard mask layer openings 131 is used to compete with the adjacent absorption layer 12a for plasma reactive ions to control the upper absorption layer 12a. The patterned horizontal etch rate is similar to the patterned horizontal etch rate of the lower absorbing layer 12b. During the patterning of the absorbing layer 12, the angle θ 1 between the sidewalls of the absorbing layer pattern 122 and the upper surface of the substrate 11 at the absorbing layer pattern 122 is between 87 and 90 degrees. The sidewall of the absorbing layer pattern 122 can be brought to a nearly vertical state, the three-dimensional structure of the absorbing layer pattern 122 is optimized, and the fidelity of the reticle M1 pattern is improved.

Finally, as shown in FIG. 3H and FIG. 3I, the polymer film 21 and the hard mask layer 13 remaining on the sidewalls of the hard mask layer openings 131 are removed (step S07), and the substrate 11 and the absorber layer pattern 122 are retained, that is, The photomask M1 of the present invention can be completed.

In addition, as shown in FIG. 5, the present invention further provides a photomask M3 including a substrate 31 and an absorption layer pattern 32. The substrate 31 is a flat plate structure. The absorbing layer pattern 32 is disposed on the substrate 31, and the absorbing layer pattern 32 has a plurality of openings 321, and the upper surface of the portion of the substrate 31 is exposed from the openings 321 . The absorption layer pattern 32 has an angle θ 3 between the sidewalls of the openings 321 and the upper surface of the substrate 31 at the absorption layer pattern 32, and the included angle θ 3 is between 87 and 90 degrees. The material of the substrate 31 is quartz, optical glass or sapphire, and the material of the absorption layer pattern 32 is a molybdenum-ruthenium multilayer film or the phase is reversed by the change of the thickness of the substrate 31. In the photomask M3 of the present invention, in the process of forming the absorption layer pattern 32, the horizontal etching rate of the absorption layer pattern 32a located at the upper portion and the absorption layer pattern 32b located at the lower portion are controlled to be close to each other, so that the sidewall of the absorption layer pattern 32 can be nearly vertical. The state of the absorbing layer pattern 32 can be optimized, and the fidelity of the reticle M3 pattern can be improved, while the light can be passed through the gap of the absorbing layer pattern 32 without being affected, so that the light intensity is maintained uniform and the optical imaging effect is increased.

In summary, the method for manufacturing the photomask and the photomask of the present invention is to deposit a polymer film on the upper surface of the hard mask layer before patterning by the absorber layer, and the sidewalls of the hard mask layer openings And the absorbing layer is exposed on the upper surface of the openings of the hard mask layers, and the polymer film covering the upper surfaces of the hard mask layer and the absorbing layer is removed, and the sidewalls remaining in the openings of the hard mask layers are utilized. The polymer film competes with the adjacent absorber layer for plasma reactive ions, so that the horizontal etch rate of the overall absorber layer is similar. During the patterning process of the absorbing layer, the angle between the sidewall of the absorbing layer pattern and the upper surface of the substrate at the absorbing layer pattern is between 87 and 90 degrees, so that the sidewall of the absorbing layer pattern can be formed. A nearly vertical state is achieved, the three-dimensional structure of the absorbing layer pattern is optimized, and the fidelity of the reticle pattern is improved.

The above is intended to be illustrative only and not limiting. Any equivalent modifications or alterations to the spirit and scope of the invention are intended to be included in the scope of the appended claims.

Claims (13)

 A method for manufacturing a reticle comprises the steps of: providing a reticle blank, the reticle blank having a substrate, an absorbing layer, a hard mask layer and a photoresist layer, the absorbing layer, the hard mask The layer and the photoresist layer are sequentially disposed on the substrate; the photoresist layer is patterned to form a plurality of photoresist layer openings, so that a portion of the upper surface of the hard mask layer is exposed from the openings of the photoresist layers; The photoresist layer is a mask, and the hard mask layer is patterned to form a plurality of hard mask layer openings in the hard mask layer, so that a portion of the upper surface of the absorber layer is exposed from the openings of the hard mask layers Removing the photoresist layer, and forming a polymer film covering the upper surface of the hard mask layer, sidewalls of the hard mask layer openings, and the absorber layer exposed on the upper surface of the hard mask layer openings; Covering the upper surface of the hard mask layer and the upper surface of the absorbing layer, the polymer film remains on the sidewall of the opening of the hard mask layer; and the hard mask layer remains in the The polymer film of the sidewall of the hard mask layer opening is a mask, and the absorbing layer is patterned Forming a plurality of absorption layer openings in the absorbing layer to expose a portion of the upper surface of the substrate from the openings of the absorbing layer; and removing the polymer film and the hard mask remaining on sidewalls of the openings of the hard mask layers Floor.    The process of claim 1, wherein the absorbing layer is patterned to form an absorbing layer pattern, the absorbing layer pattern is located at a sidewall of the opening of the absorbing layer and an upper surface of the substrate is at the absorbing layer pattern There is an angle between the angles between 87 and 90 degrees.    The process of claim 1, wherein the absorbing layer is patterned by plasma etching, and the upper surface of the hard mask layer and the polymer film on the upper surface of the absorbing layer are borrowed. It is removed by plasma etching, which is an oxygen plasma or an argon plasma.    The process method of claim 1, wherein the patterned horizontal etch rate of the layer located at the upper portion is similar to the patterned horizontal etch rate of the absorbing layer at the lower portion.    The process according to claim 1, wherein the polymer film remaining on the side walls of the openings of the hard mask layers has a thickness of 1 to 20 nm.    The process according to claim 1, wherein the polymer film is formed by chemical vapor deposition using methane, ethane or acetylene.    The process of claim 1, wherein the substrate is made of quartz, optical glass or sapphire.    The process of claim 1, wherein the absorbing layer is made of a molybdenum-ruthenium multilayer film or a change in thickness of the substrate is used to achieve phase reversal.    The process of claim 1, wherein the hard mask layer is made of chromium, chromium oxide, titanium, titanium tungsten, tungsten, tantalum nitride, hafnium oxide or titanium nitride.    The process according to claim 1, wherein the polymer film is made of a high molecular polymer.    A reticle comprising: a substrate having a flat plate structure; and an absorbing layer pattern disposed on the substrate, the absorbing layer pattern having a plurality of openings, and a portion of the upper surface of the substrate being exposed from the openings; wherein The absorbing layer pattern has an angle between the sidewall of the opening and the upper surface of the substrate at the absorbing layer pattern, the angle being between 87 and 90 degrees.    The reticle of claim 11, wherein the substrate is made of quartz, optical glass or sapphire.    The reticle of claim 11, wherein the absorbing layer pattern is made of a molybdenum ruthenium multilayer film or a change in thickness of the substrate is used to achieve phase reversal.