TWI354863B - Mask and method for forming photoresist pattern - Google Patents

Description

100-3-24 IX. DESCRIPTION OF THE INVENTION: TECHNICAL FIELD The present invention relates to a method for fabricating a photomask and a photoresist pattern, and more particularly to a chromium-free phase shifting lithography (chr〇me_less phase) Lithography, CPL) reticle and method of making a photoresist pattern using this reticle. [Prior Art] In the semiconductor process, the patterning or the doping region of each layer is determined by the lithography process. The lithography process first forms a layer of photoresist on the surface of the semiconductor wafer. Then, an exposure step and a development step are performed to transfer the pattern on the reticle to the photoresist layer on the wafer. Therefore, the quality of the mask will directly affect the advantages and disadvantages of the semiconductor process. As the integration requirements of integrated circuits become higher and higher, the line width and the size of the openings in the semiconductor process are also reduced. Therefore, the phase shift mask ' PSM lithography technology is often used in recent years. To carry out the pattern transfer. In current semiconductor processes, chrome-free phase-shift reticle is one of the more commonly used phase-shift masks. 1A to 1C are cross-sectional views showing a process of fabricating a photoresist pattern using a conventional chrome-free phase-shifting lithography mask. First, referring to Fig. 1A, a surname layer no is provided, and the meal layer 110 is, for example, a germanium substrate, a dielectric layer or a conductor layer. Thereafter, a photoresist material layer 112 is formed on the layer 110 to be etched. Photoresist material layer 112 is typically a positive photoresist. Next, referring to Fig. 1B, the photoresist material layer is exposed to step 116 by means of a mask 1 。. The photomask 1 is composed of a substrate 1354863 100-3-24 102 having a projection 1〇6 and a chrome layer ι4 disposed on the partial projection 1〇6. The material of the substrate 102 is generally quartz. The chrome layer 1〇4 is generally used as a masking layer in the mask ι. Between adjacent two protrusions 106 is an opening 108 having a depth d. The depth d of the opening 108 is such that the phase angle of the light beam passing through the opening ι 8 is equal to 180. depth. According to the above, during the exposure process, a part of the light beam passes through the protrusions 1〇6 and the openings 1〇8 of the reticle 100 which are not covered by the chrome layer 104.

An exposed region 114 is formed on the photoresist layer 112. Another portion of the beam is reflected by the chrome layer 104 to form an unexposed region 118 on the photoresist layer 112. Along with this, referring to Figure ic, after the exposure step 116 is completed, the photoresist layer 112 is subjected to a development step to transfer the bright pattern onto the photoresist layer 112 via the exposure step 116. Since the photoresist layer 112 is a positive photoresist, the exposure region 114 is exposed during the development step.

The unexposed areas 118, which are removed and used for development, are retained to form the patterned photoresist layer 112. Dare wood, and the contrast between the exposed area of the layer and the unexposed area is an important finger for lithography quality. In a lithography process, the boundary between the exposed region m and the unexposed region 118 tends to have a (10) contrast* high, resulting in a pattern resist m, which is poorly imaged, that is, in the exposed region 114. And the lack of contrast between the light and dark at the interface between the exposed areas 118 causes the pattern on the patterned photoresist layer m' to be inconsistent with the pattern on the mask 1'. One step is to make money on the follow-up side, and the image is turned into 5 1354863 100-3-24, which affects the follow-up. In view of the above, it is an object of the present invention to provide an exposure region of a photoresist layer of a photoresist layer and a second object of the present invention to provide a photoresist pattern process. The exposure area of the photoresist layer and the non-exposure area are high enough to have a bright and dark contrast ratio, so as to improve the imaging port of the photoresist pattern, the reticle is proposed, and the reticle includes a plurality of protrusions. The base f of the portion and the shielding layer disposed above the partial protrusion, wherein the adjacent two protrusions have an opening with a depth which allows the phase angle of the light beam passing through the opening to be equal to 180. . Further, the side wall of the projection on which the shielding layer is not disposed has a bevel, and the upper surface area of the projection on which the shielding layer is not disposed is smaller than the lower surface area. b According to the photomask of the embodiment of the invention, the material of the substrate is, for example, quartz. Further, the material of the above-mentioned shielding layer is, for example, chromium. The invention further provides a method for fabricating a photoresist pattern. In this method, a layer to be etched is first provided, and then a layer of photoresist is formed on the layer to be etched. Then, a photomask is used to perform the exposure step. The reticle comprises a substrate having a plurality of protrusions and a shielding layer disposed on the partial protrusions, wherein an opening between the adjacent two dogs is a depth having a depth which allows the opening of the opening 1354863 100- The phase angle of 3-24 2 is equal to 180. . Further, the protrusions on which the shielding layer is not disposed have a beveled surface and the projections g on which the shielding layer is not disposed have a surface area smaller than the lower surface area. Subsequently, the photoresist layer is developed. According to the method of fabricating the photoresist pattern according to the embodiment of the invention, the material is, for example, quartz. In addition, the material example of the above shielding layer

According to a method of fabricating a photoresist pattern according to an embodiment of the invention, the layer to be etched is, for example, a germanium substrate, a dielectric layer or a conductor layer. Since the reticle of the present invention has a slope on the side of the protrusion not covered by the shielding layer, the beam can generate a strong interference effect when the light beam emitted by the exposure source passes through the slope = large portion. The exposure area of the photoresist material on the day and the brightness of the unexposed area increase, thereby improving the image quality of the formed photoresist pattern. 9 "In addition, in the general lithography process, the use of the reticle of the present invention for the production of the resist pattern" can increase the contrast between the exposed area and the unexposed area, thereby increasing the contrast, thereby enabling the formed light to have Preferably, the quality is in order to conform to the patterned photoresist layer conforming to the mask pattern. In order to make the above and other (four), features and advantages of the present invention more obvious and easy to understand, 2A is a light diagram according to an embodiment of the present invention. _ is a cross-sectional view along the tangential line W' showing t-dimensional ^ 7 1354863 100-3-24 Referring to FIGS. 2A and 2B, the photomask includes a substrate 202 having a plurality of protrusions 206 and an aperture 208 disposed above the partial protrusions m, wherein the adjacent two protrusions have a depth between the writings. Further, the protruding portion wall on which the shielding layer 2 () 4 is not disposed has a slope 21 〇 such that the upper surface area 212 of the protruding eagle is smaller than the lower surface area 214. The material of the substrate 202 is, for example, quartz or other suitable material. The material of the masking layer 204 is, for example, chromium or other suitable material. The opening depth d allows the phase angle of the beam passing through the opening 208 to be equal to 18 〇. That is to say, 'in the process of performing exposure, when the light beam of the exposure light source passes through the region of the mask 2 that is not covered by the masking layer 204, the opening 208 having the depth d can make the phase angle of the light beam passing through equal to 18〇. . As described above, in the reticle 200, the side walls of the protruding portion 206 on which the shielding layer 2 〇 4 is not disposed are all formed by the inclined surface 210, so that in the subsequent exposure step of the photoresist material layer using the reticle 200, When the light beam emitted by the exposure light source passes through the inclined surface 210 of the protrusion 206, the beam can generate a strong interference effect of the light beam to help improve the light-dark contrast between the exposed area and the unexposed area in the photoresist material layer. 3 is a cross-sectional view of a reticle in accordance with another embodiment of the present invention. Referring to FIG. 3, in another embodiment, the difference between the mask 3 and the mask 2 is that in the mask 200, the entire sidewall of the large portion 206 on which the shielding layer 204 is not disposed is It is composed of the inclined surface 210, and only a part of the side wall of the protruding portion 306 in which the shielding layer 304 is not disposed above the mask 3 is a slope 310. Fig. 4 is a graph showing the contrast between light and dark obtained by the reticle 2 〇〇 and the conventional reticle after exposure simulation of 1354863 100-3-24. In the thin position of the cover, the vertical Si resist layer simulates the __ dark contrast curve with respect to the f-light shield and the light source ίί.

The position 詈\ can be seen that the position of the curve Α distribution is higher than the curve Β distribution. The reticle 200 is measured by the exposure simulation test. The brightness and darkness measured by the reticle is large. That is, to the light with better image quality. A method of fabricating a photoresist pattern in the reticle 2 will be described below. 5A through 5C are cross-sectional views showing a manufacturing process in accordance with an embodiment of the present invention.

Referring to FIG. 4 in May First, referring to FIG. 5A, a layer 500 to be etched, such as a ruthenium substrate, a dielectric layer or a conductor layer, is provided. Thereafter, a photoresist material layer 502 is formed on the layer of the surname. The layer of photoresist material is, for example, a positive photoresist. Next, referring to FIG. 5A, an exposure step 504 is performed on the photoresist layer 5〇2 using the photomask 2〇〇. After the light beam emitted by the exposure light source passes through the photomask 2, the photoresist material layer 502 irradiated by the light beam forms an exposed region 5〇6, and the photoresist material layer 5〇2 which is not irradiated by the light beam forms an unexposed portion. Area 508. Since in the reticle 200, the side wall of the protruding portion 206 on which the shielding layer 204 is not disposed has the inclined surface 21 〇, the interference effect by the light beam having the protruding portion 206 of the inclined surface 210 when the exposure step 504 is performed 9 1354863 100-3-24 Since the protrusion with the bevel 210 enhances the dryness of the beam = it should therefore increase the junction-dark contrast between the exposed area in the photoresist layer 5G2 and the unexposed area 5G8. Accordingly, referring to Fig. 5C, the photoresist layer 5 is subjected to a step of forming a pattern to form a patterned photoresist layer 5?. Since the photoresist layer 5〇2 is a positive photoresist, the exposure (4) 506 is removed by the action of the developer, and the unexposed area 5〇8 which does not interact with the developer is retained. The shape of the film is thin. In particular, since the contrast between the exposed area 506 and the unexposed area has increased, the filming step has a better image quality and can be combined with the mask. The pattern on the 5th is the same. In addition, in the subsequent (four) process towel, the etched layer 5 〇 0 is etched by the preferred patterned photoresist, and the error caused when the hood pattern is transferred to the layer to be immersed is further reduced. In summary, in the reticle of the present invention, since the side wall of the canine portion which is not covered by the shielding layer has a slope, the light beam from the exposure light source passes through the protruding portion having the inclined surface, which can generate a strong sneak effect. The contrast between the exposed area and the unexposed area of the photoresist layer is increased, and a photoresist pattern having better image quality can be obtained.曰^ In addition, the use of the above-mentioned photomask to fabricate the photoresist pattern can be applied to a silk with better image quality, and can be effectively and effectively used when the photoresist pattern is used as a mask for the layer (10). The reticle pattern is transferred to the layer to be _, to avoid the influence of the pattern transfer error on the subsequent process. Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and those skilled in the art can make some modifications and refinements without departing from the spirit and scope of the present invention. The scope of the invention is defined by the scope of the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1A to Fig. ic are cross-sectional views showing a process for producing a photoresist pattern using a conventional opaque phase shifting lithography mask. Figure 2A is a perspective view of a reticle in accordance with an embodiment of the present invention. 2B is a cross-sectional view taken along line tangential to FIG. 2A. FIG. 3 is a cross-sectional view of a reticle according to another embodiment of the present invention. - Figure 4 is a graph showing the contrast between light and dark obtained after exposure simulation of the mask 200 of the present invention and a conventional mask. 5A to 5C are plan views showing the manufacturing process of the photoresist pattern of the rice in accordance with an embodiment of the present invention. [Description of main component symbols] 100, 200, 300: reticle 102, 202, 302: substrate 104: chrome layers 106, 206, 306: protrusions 108, 208, 308: openings 110, 500: layers 112, 502 to be etched Photoresist material layer 112', 502': patterned photoresist layer 1354863 100-3-24 114, 506: exposed areas 116, 504: exposure steps 118, 508: unexposed areas 204, 304: masking layers 210, 310 : Bevel 212 : Upper surface area 214 : Lower surface area A, B : Curve d : Depth

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Claims (1)

1354863 100-3-243⁄4 10. Patent application scope: 1. A reticle comprising: a substrate having a plurality of protrusions, and an opening having a depth between adjacent ones of the protrusions, The depth allows the phase angle of the beam passing through the opening to be equal to 180. And a shielding layer disposed on a portion of the protrusions, wherein sidewalls of the protrusions on which the shielding layer is not disposed have a slope and the protrusions on the shielding layer are not disposed thereon The upper surface area of the portion is smaller than the lower surface area. 2* The photomask of claim 1, wherein the material of the substrate comprises quartz. 3. The reticle of claim 1, wherein the material of the shielding layer comprises chromium. A method for fabricating a photoresist pattern, comprising: _ providing a layer to be etched; forming a photoresist layer on the layer to be scribed; performing an exposure step using a mask, the reticle comprising: a substrate The substrate has a plurality of protrusions, and an adjacent one of the adjacent σ 卩 is an opening having a depth that allows the phase angle of the light beam passing through the opening to be equal to 18 〇. And a shielding layer disposed on a portion of the protrusions, wherein a sidewall of the protrusions on which the shielding layer is not disposed has a slope, and the protrusions on which the shielding layer is not disposed are disposed The upper surface area of the 13 1354863 100-3-24 is less than the lower surface area; and a development step is performed. 5. The method of fabricating a photoresist pattern according to claim 4, wherein the material of the substrate comprises quartz. 6. The method of fabricating a photoresist pattern according to claim 4, wherein the material of the mask layer comprises chromium. 7. The method of fabricating a photoresist pattern according to claim 4, wherein the layer to be etched comprises a stone substrate, a dielectric layer or a conductor layer.