TW539917B - Photomask combination and its exposure method for forming fine pattern - Google Patents

Abstract

This invention discloses a photomask combination, which comprises: a first photomask containing a plural number of 0 degree phase light-transmission region and a plural number of 180 degree phase light-transmission region arranged in a parallel and interlaced fashion; and a second photomask containing a transparent substrate and a stripe type light-shielding layer, in which the above-mentioned stripe type light-shielding layer covers a portion of the surface of the transparent substrate, and the width of the stripe type light-shielding layer is not smaller than the space between the 0 degree phase light-transmission region and the 180 degree phase light-transmission region. This invention also discloses a fine pattern formation method by exposure through the photomask combination.

Description

539917

[Technical field to which the invention belongs] The present invention relates to a method for manufacturing a semiconductor integrated circuit, and more particularly to a fine pattern exposure method for a lithography process. 》 'And [Prior art] / In the manufacturing process of semiconductor integrated circuits, the microlithography process undoubtedly occupies a very important position, and the design pattern can be accurately defined in light by this process. The resist layer 2 then uses an etching process to transfer the pattern of the photoresist layer to a semiconductor substrate & Generally speaking, the lithography process mainly includes several methods including priming, coating, pre-baking (or soft baking), exposure 5 (expose), post-exposure processing, development, and hard baking. step. ^ The resolution of the exposure procedure is particularly critical for whether the component accumulation can be further improved. All major semiconductor manufacturers have actively invested in research and development in order to achieve a higher level. However, with the rapid increase of the integration level of semiconductor integrated circuits, the line width required by the lithography technology is also getting smaller and smaller. Similarly, the distance between the semiconductor elements is also shortening. However, the distance between the above-mentioned components is physically limited due to the influence of optical characteristics during the exposure process. The reason is that in order to obtain a micro-sized element during exposure, the interval between the light-transmitting regions of the photomask will be reduced in accordance with the size of the element. (1/2 or less), the light passing through the mask will be diffracted, which will affect the resolution of the transferred pattern. Furthermore, when the density of the light-transmitting area on a reticle varies, the light passing through the dense light-transmitting area will be passed through.

539917 V. Description of the invention (2) The isolated light-transmitting area is distorted, which makes it difficult. In view of this, a mask combination and its definition gate pattern are provided for understanding. [Summary of the Invention] The purpose of the present invention _ line pattern exposure method, the purpose of the present invention two line pattern exposure method, the main features of the present invention such as: staggered phase shift mask) light (second exposure): The staggered bright areas and the bright field of the dark field fall in the adjacent bright area, that is, the original multiple areas of the adjacent bright area are subject to secondary exposure. The dark area forms a fine method to achieve the above purpose. The steps of this method first provide a first light effect, so that the exposure of the pattern after exposure to the 'fine pattern (eg, gate layer) determines the above problems. The main purpose of the present invention is to provide an exposure method for forming a thin line pattern, which is applicable to provide a photomask combination and its formation to avoid distortion or distortion of the exposure pattern. It is to provide a photomask combination and a thin line pattern formed by exposing it to a fine arrangement. The key lies in the use of a phase shift mask (PSM) (for example, a second exposure with a conventional structure mask to expose the phase shift mask to a plurality of parallel cross structure masks to expose a pattern with stripe dark areas. The key is When exposing, it is necessary to combine the two patterns between the strips to form a thin line pattern. The pattern of the bright areas staggered in parallel is masked by the dark area of the other one, so that the pattern is so, leaving only the adjacent Bright area line pattern. 'The present invention proposes a thin line pattern exposure including: photomask' having a plurality of parallel and staggered arrangements.

0503-7594TWF (Nl); TSMC2001-1582; Felicia.ptd page 6 539917 V. Description of the invention (3) '--- Phase 0 degree transmission area and complex phase 丨 80 degree transmission area. A second photomask is provided, which has a transparent substrate and a strip-shaped light-shielding layer, wherein the strip-shaped light-shielding layer is restored on the surface of the portion of the transparent substrate, and the width of the strip-shaped light-shielding layer is not less than the phase-degree light-transmitting area and the phase. The phase is 180 ° between the light-transmitting areas. Then, a first exposure pattern and a second exposure pattern are exposed through the first mask and the second mask, respectively, wherein the first exposure pattern has a plurality of bright areas arranged in parallel, and the second exposure pattern It has a strip-shaped dark area located at an interval between the adjacent bright areas. In order to achieve the above-mentioned object, the present invention also proposes a photomask combination, suitable for exposing a thin line pattern, including: a first photomask having a parallel and staggered complex phase 0 degree light transmission area and a complex phase 180 degree A light-transmitting area; and a second photomask, which is covered with a transparent base in a stripe form, wherein the stripe light-emitting layer covers the surface of the transparent base portion, and the width of the stripe-shaped light-shielding layer is not less than the phase of 0 degrees. The distance between the light area and the aforementioned 180-degree light-transmitting area. As described above, the first photomask is, for example, an alternating phase shift mask (aHernate pSM), and the second photomask is, for example, a binary intensity mask (BIM). Ben Maoming, the above-mentioned phase 0-degree light-transmitting region and the above-mentioned phase 180-degree light-transmitting region have the same shape (for example, rectangular) and the same size. The width of the phase-transmissive area with a phase of 0 degrees and the phase-transmissive area with a phase of 180 degrees is preferably about 170 ~ 400 mm. The distance between the two is preferably about 15 to 60 nm. In addition, the material of the strip-shaped light-shielding layer is made of metal chromium, and its width is preferably about 539917. V. Description of the invention (4) '~ --- 7 0 to 90 nm. In order to make the above-mentioned objects, features, and advantages of the present invention more comprehensible, the preferred embodiments are described in detail with reference to the accompanying drawings. [Embodiment] Please refer to FIG. 1 and FIG. The top view of the mask of FIG. 2 and the exposure image diagrams of FIGS. 3, 4, and 5 are used to illustrate the present invention—the embodiment of the invention—forming a plurality of thin line patterns. Baixian, please refer to FIG. 1. The first mask 600 is preferably an alternating phase shift mask (alternating PSM) to eliminate the optical proximity effect ^ E) The first mask is mainly used for exposing a plurality of Dark field pattern of bright areas arranged in parallel. The above-mentioned first reticle 600 has a plurality of phase-transmitting areas 0 ° and a plurality of phase-transmitting areas 604 of parallel phase 0 ° and a parental arrangement. The first photomask 600 may be composed of a first transparent substrate (eg, quartz glass), and the light transmitting regions 602 and 604 may be controlled by controlling the thickness of the first transparent substrate to separate A phase angle 0 degree light transmission area 602 and a phase angle 180 degree light transmission area 604 are formed, where the phase angle 0 degree light transmission area 60 2 and the phase angle 180 degree light transmission area 604 are staggered. Exposure " When the wavelength of the light source is 193nm and the refractive index of quartz glass is l 552, the thickness of the 0-degree light-transmitting region is the thickness of the quartz, and the thickness of the phase 180-degree light-transmitting region and the phase 0-degree light-transmitting region differ by 170 ~ 180nm, preferably HSnm. In addition, a semiconductor substrate is provided. The surface of the semiconductor substrate can be formed with an appropriate photoresist layer by, for example, a bismuth coating method, and the semiconductor substrate is set and fixed on a ceremony device.

539917

Next, the first photomask 600 is placed in an exposure device, and the first photomask 600 is aligned at a predetermined position of the semiconductor substrate pre-exposure pattern using the exposure device. The above exposure device is, for example, a step-and-repeat mask aUgner, a mask aligner, a scan_and_repeat_sk aligner, or any conventional exposure device. Next, an exposure process is performed, and a first exposure pattern 600 is exposed through the first mask 600 using the exposure device, and the first exposure pattern 600 is a dark field pattern and has a parallel arrangement. The plurality of bright areas 6020 are shown in FIG. 3. In addition, referring to FIG. 2, a second photomask 8o {) is provided, which can be any conventional photomask, and is preferably a conventional dual intensity mask (BIM). The second photomask 800 is mainly used for exposing a bright field pattern with a stripe of dark areas. The second and cover mentioned above are composed of a second transparent substrate (for example, quartz glass), and the other two shells are, for example, a stripe of light-shielding layer 802 of metallic chromium (Cr), which is covered by Sundial-Transparent. Substrate surface. It must be noted that the above-mentioned stripe light-shielding layer 80 = 1 degree V must not be greater than (greater than or equal to) the above-mentioned phase 0 degree light transmission area 602 and the phase 180 degree light transmission area 604% ( '>%). Then, δ sets the second photomask 800 in the exposure device. The position of the second mask_ is adjusted by the exposure device, so that the light layer 802 is aligned at an interval position of one of the adjacent bright areas 6020 of the first exposure pattern 6000. Next, a double exposure process is performed. Exposure using the above exposure device

539917 V. Description of the invention (6) The second mask 80 0 exposes areas that are not in the stripe light-shielding area. In this way, the second mask is exposed by the following: f light pattern = 〇〇 ( As shown in FIG. 4), a strip-shaped dark area 8020 is just heavy, on one of the spaces between adjacent bright areas of the first exposure pattern 6000 described above. ^ The result that the above first exposure pattern 6000 overlaps with the above second exposure pattern 8000 is as shown in FIG. 5, leaving only a field pattern with a stripe dark area of 9 02 0 = 00 in the semiconductor substrate. . In this way, the pattern of the stripe dark area ⑽ can be quite fine. A mask assembly according to the present invention includes: the first mask and the second mask 800. The above-mentioned first photomask 600 has parallel and staggered rows / columns of a complex phase 0 degree light-transmitting area 602 and a complex phase 180 degree light-transmitting area ㈣ ′, which are formed by different transparent substrate thicknesses. In addition, the second photomask ㈣0 has a transparent substrate and a strip-shaped light-shielding layer 802, wherein the upper layer 802 covers the surface of the transparent substrate Qiu Bamai dull occluded soil P knife surface, the strip-shaped The visibility% of the light-shielding layer 8 〇2 is not less than the phase 0 degree light-transmitting area 602 and the above-mentioned phase "ο light area 604. The distance wjwpwj. Taxi": the spirit of the Ming 'Although the embodiment described above is executed Addicted-human exposure 'and then perform the above-mentioned double exposure, that is, first expose the pattern of the above-mentioned photomask_ and then expose the above-mentioned second photomask, but the execution of the first-time and double-exposure procedure of the present invention is to Interchange, as long as you pay attention to align the photomask, so that the above complex will crystallize with the adjacent bright area 60 2 0, that is, "pot" is not limited. Repeated text can be one of the pure sequence of T

539917

539917 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view showing a photomask according to a preferred embodiment of the present invention. Fig. 2 is a plan view showing another photomask assembly according to a preferred embodiment of the present invention. Figure 3 shows the image pattern obtained by exposing the mask according to Figure 1. Figure 4 shows the image pattern obtained by exposing the mask according to Figure 2. Fig. 5 shows the exposure result of a thin line pattern according to a preferred embodiment of the present invention. [Symbol description] 60 0 ~ first photomask; 80 0 ~ second photomask; 60 2 ~ phase 0 degree light transmission area; 604 ~ phase 180 degree light transmission area;

Wi ~ space width of adjacent light-transmitting areas; 601 ~ light-shielding layer of the first mask; 800 ~ second mask; 8202 ~ striped light-shielding layer; 60000 ~ first exposure pattern; 60 2 0 ~ bright area; W2 ~ width of stripe light-shielding layer; 9 020 ~ thin line pattern; 8 020 ~ stripe light-shielding layer pattern; 9000 ~ resulting pattern of second exposure.

0503-7594TWF (Nl); TSMC2001-1582; Felicia.ptd page 12

Claims (1)

539917 VI. Application Outline " --- 1 · An exposure method for forming a thin line pattern, including: · Providing a first photomask 'with parallel and staggered complex phase 0 degree light transmission area and complex phase 18 ° Provide a second photomask with a transparent substrate and a strip-shaped light-shielding layer, wherein the strip-shaped light-shielding layer covers the surface of the transparent substrate, and the width of the strip-shaped light-shielding layer is not less than the phase. A distance between the light area and the light-transmitting area with a phase of 180 °; and a first exposure pattern and a first exposure pattern are exposed through the first mask and the second mask, respectively, wherein the first exposure pattern has • ^ = arranged = a plurality of bright areas, the second exposure pattern has a strip-shaped dark area, so that the first strip-shaped dark area appears at one of the intervals between the adjacent bright areas. 2. The method for exposing a thin line pattern as described in item 丨 of the patent application, wherein the light-transmitting region with a phase angle of 0 degrees and the light-transmitting region with a phase angle of 180 degrees have the same shape. , 3 • The exposure method for forming a thin line pattern as described in item 1 of the declared patent scope, wherein the above-mentioned phase angle 0 degree light transmission area has the same size as the above-mentioned phase angle "o degree light transmission area." 4, as stated in the patent The exposure method for forming a thin line pattern as described in the first item of the scope, wherein the light transmission region with a phase angle of 0 degrees is rectangular. Qitu 5 · t! The exposure method for forming a thin line pattern as described in the first item of the Ming Patent Scope ' The light-transmitting area with a phase angle of 18 ° is rectangular. * The exposure of the thin line pattern described in item 1 of this 6, ΐt patent range, the light-transmitting area with a phase angle of 180 ° and the above Phase angle of 0 degree Page 13 539917 VI. Scope of patent application Pitch is 15 ~ 60 0 m. 7. The exposure method for forming a thin line pattern as described in item 1 of the scope of the patent application, wherein the width of the light-transmitting region with a phase angle of 0 degrees is 170-400 nm. 8. The exposure method for forming a thin line pattern as described in item 1 of the scope of the patent application, wherein the width of the light-transmitting region with a phase angle of 180 degrees is 170-400 nm. 9 · The exposure method for forming a thin line pattern as described in item 1 of the scope of the patent application, wherein the material of the stripe-shaped light-shielding layer is made of metallic chromium. 10 · The exposure method for forming a thin line pattern as described in item 1 of the scope of the patent application ', wherein the width of the stripe-shaped light-shielding layer is 70 to 90 nm. Η · The exposure method for forming a thin line pattern as described in item 1 of the scope of the patent application, wherein the first photomask is an alternate phase shift mask (aiternai: e PSM). 12. The exposure method for forming a thin line pattern as described in Item + of the patent application, wherein the second photomask is a dual intensity mask (BIM). y 13 · —An exposure method for forming a thin line pattern, including: providing a first photomask in an exposure device, wherein the first photomask has a parallel and staggered multiple-phase light transmission area and a multiple-phase 18; Duto 7U ΙΞΕ > Provide a semiconductor substrate on the support device; align the first photomask at a predetermined position on the semiconductor substrate. J == exposure device exposes one top through the first photomask ^ Mystery—Multiple Exposure Patterns with Parallel Arrangements & 0503-7594TWF (Nl); TSMC2001-1582; Felicia.ptd p. 14 539917 A second photomask is provided in the exposure device, the cover in the bean has a transparent substrate and a stripe light-shielding layer, and the stripe-shaped cover in #: the layer is covered on the surface of the transparent substrate portion, and the stripe-shaped light-shielding layer The wide yield is not less than between the phase 0-degree light-transmitting area and the phase 180-degree light-transmitting area; using the exposure device to align the strip-shaped light-shielding layer of the second photomask to the first exposure pattern. The spaced positions of the bright areas; and using the above-mentioned exposure device to expose areas other than the stripe-shaped light-shielding layer to 'expose only stripe-shaped dark areas in the semiconductor substrate. 14. The exposure method for forming a thin line pattern as described in item 13 of the scope of the patent application, wherein the light-transmitting region with a phase angle of 0 degrees and the light-transmitting region with a phase angle of 180 degrees have the same shape. 15. The exposure method for forming a thin line pattern as described in item 丨 3 of the scope of the patent application, wherein the size of the light-transmitting area with a phase angle of 0 degrees and the light-transmitting area with a phase angle of 180 degrees are the same. 16 · The exposure method for forming a thin line pattern as described in item 13 of the scope of the patent application, wherein the light-transmitting region with a phase angle of 0 degrees is rectangular. 17 · The exposure method for forming a thin line pattern as described in item 13 of the scope of the patent application, wherein the light transmitting region with a phase angle of 180 ° is rectangular. 1 8 · The exposure method for forming a thin line pattern as described in item 13 of the scope of the patent application, wherein the distance between the light-transmitting region with a phase angle of 180 degrees and the light-transmitting region with a phase angle of 0 degrees is 15 to 60 nm. 19 · The exposure method for forming a thin line pattern as described in item 13 of the scope of the patent application, wherein the width of the light-transmitting region with a phase angle of 0 degrees is 170 to 400 nm. 2 0 · Exposure to form a thin line pattern as described in item 丨 3 of the scope of patent application 0503-7594IWF (Nl); TSMC2001-1582; Felicia.ptd page 15 539917 VI. Scope of patent application Light method 'wherein the above-mentioned phase angle light transmission G has a degree of 170 ~ 400ηπ. 2 1 · The exposure method for forming a thin line pattern as described in item 3 of the scope of the patent application, wherein the material of the stripe light-shielding layer is made of metallic chromium. 2 2 · The exposure method for forming a thin line pattern as described in item 13 of the scope of the patent application, wherein the width of the stripe light-shielding layer is 70-90 nm. 2 3 · The exposure method for forming a thin line pattern as described in item 13 of the scope of patent application ', wherein the first photomask is an alternate phase shift mask (alternate PSM) 〇 2 4 · As the scope of patent application The exposure method for forming a thin line pattern as described in item 3, wherein the second mask is a dual intensity mask (BI M) ° 25 · — a combination of masks suitable for exposing a thin line pattern, including : A first photomask having parallel and staggered multiple-phase 0-degree light-transmitting regions and multiple-phase 180-degree light-transmitting regions; and a second photomask having a transparent substrate and a strip-shaped light-shielding layer, wherein The strip-shaped light-shielding layer covers the surface of the transparent base portion, and the width of the strip-shaped light-shielding layer is not less than the distance between the phase-degree light-transmitting area and the phase-degree light-transmitting area. 26. The photomask combination according to item 25 of the scope of the patent application, wherein the phase-transmissive area with a phase of 0 degrees and the phase-transmissive area with a phase of 180 degrees have the same shape. 27. The photomask combination according to item 25 of the scope of application for a patent, wherein the phase 0 degree light transmission area has the same size as the phase 18 degree light transmission area. 28. The mask assembly according to item 25 of the scope of application for a patent, wherein the light-transmitting area with a phase of 0 degrees is rectangular. 539917 Patent application scope, 29. The photomask combination described in item 25 of the patent application scope, wherein the phase-transmitting area of 180 degrees is rectangular. , 3 0 · The photomask combination according to item 25 of the scope of the patent application, wherein the distance between the phase 180 degree light transmission area and the phase 0 degree light transmission area is 2 0 ~ 1 0 Onm 〇, 3 1 The photomask combination according to item 25 of the scope of the patent application, wherein the width of the light-transmitting region with a phase of 0 degrees is ~ 400 nm. 3 2 · The photomask combination according to item 25 of the scope of the patent application, wherein the width of the 180-degree phase transmission area is ho ~ 400nm. 3 3 · The photomask combination according to item 25 of the scope of patent application, wherein the material of the stripe light-shielding layer is composed of a metal network. 34. The photomask combination according to item 25 of the scope of patent application, wherein the width of the stripe light-shielding layer is 300 to 600 nm. 3 5 · The photomask combination described in item 25 of the patent application scope, wherein the first photomask is an alternate phase shift mask (alternating PSM) 〇 3 6 · As the patent application scope of the second 5 The mask combination described in the above item, wherein the first mask is a dual intensity mask (BIM). 0503-7594TWF (Nl); TSMC2001-1582; Felicia.ptd p. 17