TW200419303A - Half-tone phase shift mask and forming method of pattern by using thereof - Google Patents

Abstract

A half-tone phase shift mask is consisted of mask substrate, half-tone phase shift layer and a shelter layer. The half-tone phase shift layer with bar shape is covered on the mask substrate surface. The shelter layer is covered on two ends of the half-tone phase shift layer, and exposes a part of the half-tone phase shift layer. Wherein the width of shelter layer is larger than the width of the half-tone phase shift layer.

Description

200419303 V. Description of the invention (l) [Technical field to which the invention belongs] The present invention relates to a photomask and its application, and in particular to a half-tone phase-shift photomask and the use of this half-tone phase shift Method for forming a photomask. [Prior art] As the integration degree of integrated circuits is increasing, the accuracy of semiconductor processes becomes extremely important. Because once a slight error (E r r 〇 r) occurs in the process, it may cause the process to fail, resulting in the damage or scrap of the wafer, thus consuming a lot of costs.

Photolithography can be said to be one of the most important steps in the entire semiconductor manufacturing process. Regardless of the time, the doping process needs to be achieved through the lithography process. In the lithography process, the exposure resolution (Resolution) and depth of focus (DOF) are important indicators of lithography quality. On the chromium film resist layer, the size of 0 · 1 8 is smaller than before (Line (Ass is Lithog, 0 · 18 micrometers or more). In the semiconductor process, the quartz plate coated with 2 is used. The elementary (Binary) mask can be used to transfer a good pattern in the light tooth. However, when the semiconductor process enters Ι 1 (such as 0.13 microns), because of the holes and line width of the pattern

Shrinking makes the problem of diffracting light more serious. Therefore, the phase shift mask (PSM) technology is used to size the holes and line widths of the pattern. In addition, for the reduction of the line pattern Feature Size, π »+ R.), Auxiliary bars are required. ^ I phaseless lithography (Chromoless phase raphy (CPL)), _ false phase shift mask (Alternative

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V. Description of the invention (2) PSM ’altPSM) (or Levenson PSM) is achieved with a light source with a wavelength of 248nm. In the above-mentioned technology, the resolution of the staggered phase shift photomask is very high for adding special areas (such as the actual gate area (True Gate), that is, the part where the gate conductor layer spans the main area). Useful technology. However, the staggered phase shift mask technology requires the use of so-called double exposure, that is, two different masks are used for the exposure process. For example, when making a gate pattern as shown in Figure 1 (both ends are thick and the middle is thin), for example, first use a binary mask 200 (Binary Mask) (blank part) as shown in Figure 2A. Is the light-transmitting area 202, the oblique line is the opaque area 204) After one layer of exposure is performed, the phase-shifting photomask 210 (the blank portion is the light-transmitting area 212 and the oblique line is Opaque area 2 14) to perform exposure. However, using this method of replacing different photomasks for re-exposure and re-exposure can easily cause errors in alignment and decrease productivity. In addition, in order to avoid misalignment, placing a reticle on the photomask or designing software to precisely control the exposure machine (=. Stepper) will also cause problems of rising costs. [Summary of the invention] # In view of this, the object of the present invention is to provide a half-tone phase; a mask and a pattern forming method using the half-tone phase-shifting photomask to solve ^ :: 以 改 ^ 一 ... The photomask is used for double exposure, which can reduce the problem of aligning the la block, reducing the yield and increasing the cost. The invention provides a half-tone phase-shifting light i, which is composed of a base, a half-tone phase-shifting layer, and a light layer. Half-tone phase shift =

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It is on the surface J1 of the photomask base, and the half-tone phase shift layer is stripe. The masking layer covers the two ends of the half-tone phase shift layer and exposes part of the half-tone phase shift layer. The width of the masking layer is larger than the width of the half-tone phase shift layer. The material of the photomask substrate includes quartz glass. The half-mode phase shift layer has a phase shift of 180 degrees. The material of the I-mode phase shift layer includes chromium oxynitride (CrON), chromium oxide (CrO), and molybdenum silicon nitride oxide (MoSizOxN crystalline carbon). And silicon nitride (S i N). 'The present invention also provides a pattern forming method using a half-tone phase-shifting photomask, which is suitable for forming a stripe pattern that is thick at both ends and thin in the middle. This method is provided first. A substrate, it forms a material layer on this substrate. Then, a-layer photoresist layer is formed on the material layer, and the photoresist layer is patterned using a half-tone phase shift mask, and the half-tone phase shift light The mask is at least composed of a mask base, a half-tone phase shift layer, and a shielding layer. The half-tone phase shift layer covers the surface of the mask base, and the half-tone phase shift layer is stripe. The masking layer covers the half The two ends of the shape-shifting phase shift layer expose part of the half-mode phase shift layer, and the width of the masking layer is larger than the width of the half-mode phase shift layer. Then, the patterned photoresist is used to determine: the material layer, forming a Both ends are thick and thin with a stripe pattern. Among them, the material of the mask base includes quartz glass. Half-tuned phase shift Reed has a phase shift of 180 degrees, and the material of the half-tuned phase shift layer includes nitrogen oxide (CrON), chromium oxide (cr〇), molybdenum silicon nitride oxide () ^ 〇31 〇N crystalline carbon And silicon nitride (SiN). ZX " The present invention is covered on the surface of the same photomask with a half-tone phase-shifting speckle layer and a shielding layer (binary pattern layer) to solve the conventional misalignment ^ This reduces the problem of productivity, and can also reduce the manufacturing cost of photomasks.

10619twf.ptd Page 7 2UU419303 V. Description of the invention (4) Moreover, the half-tone phase shift layer of the present invention constitutes the masking area of the photomask using the shield layer and the half-tone phase, which can further improve the lithography analysis; Not only is the conventional staggered phase-shift type ^ which is beneficial to the photomask, the pattern formed by the eye-shift type photomask and the pattern phase of the half-tone phase-shift photomask = 1 ... The influence is small, that is, the duty ratio (Duty Rati0) has a better degree of uniformity with respect to the above-mentioned and other keys of the present invention. It is easy to understand, the following special mentions-better: Shi Er's, characteristics, and advantages can be explained in more detail as follows: {Only by way of example, and in conjunction with the drawings, detailed [implementation] Figure 3 A This is a structure view from the top of the Zhaomu Su-type photomask. No. =: Half-tone phase shift of the Jiaguan embodiment. The light intensity after the light is illuminated on the mask in the A_A ′ section in the figure is cloth. The 3D picture is green " Qianfan q δ m 丄 light intensity distribution. Fig. 3E is: The shadow mask on the wafer when the profile of = AΪΓ-β 'is used to form the gate conductor and the metal wiring word chart: the mask shown in the figure can be a fine shape, for example. Xiangda University ’s pattern has a thick center at both ends. Please refer to Figures 3A and 3B. The semi-modulated phase-shifting photomask 300 according to the present invention is composed of a photomask base 302 and a half-adjusting phase-shifting layer. 304 and a shielding layer 306. The material of the mask base 30 2 is, for example, quartz glass. A half-tone phase shift 304 is provided on the mask base 302. An example of the pattern of this half-tone phase shift layer 304

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200419303 V. Description of the invention (5) If it is arranged in a stripe, its I degree is W1. The half-tone phase shift layer 3 04 is, for example, that when light passes through the half-tone phase shift mask 300, it can have a phase shift of 800 degrees, that is, an optical path of 180 degrees difference. The material of the half-tone phase shift layer 3 04 is, for example, chromium oxynitride (CrON), chromium oxide (Cr0), molybdenum silicon nitride oxide (MoSiz0xNy), amorphous carbon, nitride nitride (SiN), etc. The partially light-transmitting material may have a transmittance of about 2% to 100%, preferably about 4% to 10%, and the transmittance of molybdenum silicon nitride oxide is about 6%. The masking layer 300 is disposed on the half-tone phase shift layer 304. This masking layer 30 covers both ends of the half-tone phase shift layer 304 and exposes the central portion of the half-tone phase shift layer 304. . The width W2 of the shielding layer 306 is larger than the width wi of the half-tone phase shift layer 304. The material of the shielding layer 30 6 is, for example, chromium. The area covered by the shielding layer 306 and half-shaping = shift layer 304 constitutes the pattern 308 of the lithography process, such as the pattern of the gate conductor, metal connection, word line or bit line. The area not covered by the reed 306 and the half-tone phase shift layer 304 is the light transmitting area 31. In addition, the pattern formed by the half-tone phase-shifting optical army of the present invention has a shape with thick ends and thin middle ends. When the light source passes the half-tone phase-shifting photomask of the present invention, the transmittance of the half-shift layer 304 is about 6%. As for the light-transmitting area 310 between the patterns 308, the unshielded material covers it. , The light source can transmit directly 'so its transmittance is about 100%. As far as the phase shift angle is concerned, the transmission area 3o0 has no effect, so its phase shift angle is zero. , And the phase shift of the half-tone phase shift layer 304 is ⑽. . Due to A, the half-tone phase of the present invention in the lithography process is the light intensity distribution as shown in Figures 3C and 3D. The area covered by the masking layer 306 is not exposed during the lithography process

200419303 V. Description of the invention (6) 'Partial' However, in order to cancel the diffraction effect of the light source, a half-tone phase shift layer 3 0 4 'is used to cause 1 8 0. Phase shift angle to offset the diffraction effect at the periphery of the shielding layer 306 'and can cause 0 points to increase its contrast (contrast) and resolution (thus the light intensity distribution of the wafer on the lithography during the photolithography is as in Section 3E As shown). The above describes the half-tone phase-shifting photomask of the present invention, and then describes the pattern forming method using the half-tone phase-shifting photomask of the present invention. FIG. 4A to FIG. 4B are perspective views illustrating a gate process performed by using a half-tone phase-shifting photomask according to a preferred embodiment of the present invention. First, referring to FIG. 4A, a semiconductor substrate 400 is formed—layer = material layer 402. The material of this material layer 402 includes a conductive material, a dielectric material, and the like. In this embodiment, the material of the material layer 402 is made of polycrystalline silicon for explanation. The formation method is, for example, a chemical vapor deposition (cVD) method. Then, a photoresist layer is coated on the material layer, and then the photoresist layer is exposed and developed using the half-tone two-shift photomask of the present invention (as shown in FIG. 3A) & The photoresist pattern 400 shown in FIG. 4A. Next, the photoresist pattern 404 is used as a mask to etch the material layer 402. For example, an anisotropic dry method is used to form the material layer 402a. After that, the photoresist pattern 400 is removed, and subsequent processes are performed (as shown in FIG. 4B). Since the material layer 402 is a lithography process using a half-tone phase-shifting photomask not shown in the figure, the material layer 2a can be formed into a thick and thin shape at both ends, and the material layer M can be formed. The depth of two is W 3, which is, for example, about 0.15 μm, and the width of the material layer 4 02 a is W 4, which is, for example, about 0.99 μm to about 13 μm. The half-tone phase-shifting photomask of the present invention

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V. Description of the invention (7) The masking layer constitutes a light star> # ^, there is a 180 ° phase bar ^ masking area, and the image between the half-tone phase shift layer and the masking layer can be enhanced, which can not only offset the edge of the masking layer The relationship between the shadow effect of the shadow area of the second shot * and the improvement of the resolution during the lithography. (Duty Ratl0 vs. key rule width)). In Figure 5, the line width (SpaCing / Une indicates the present invention. In the 5th gang, the conventional technology is represented by the symbol-^ when the duty ratio is 1 = ruler = pattern formed by the mask of the present invention '

Bb ^, Γ〇9 ^; ·] Π ^^; Ping. Yongtian Yi A 10, · 09 is not around; the difference between the two is a pattern formed by the method 0, 0, 2 micro ', ^ white 〇, when the duty cycle is 1, the key scale left ΐ; when the duty cycle At 8, the key dimension is about G.125 Dewei, the difference between the two is 0.0 25 microns. Therefore, with the pattern t of the mask formed by the present invention, the effect of the duty ratio on the critical dimension is small, and the uniformity of the critical dimension is good. d W »1 t

Please refer to Figure 6 for the relationship between the size of the pitch key under different exposure energies. Among them, the width of the masking layer of the photomask is set to 15 micrometers, and the width W2 of the half-tone phase shift layer is 0 · 丨 丨 micrometer. In Figure 6, the ^ ·-◊-represents the exposure energy of 315 J / m2, the symbol-represents the exposure energy of 330 J / M, and the symbol represents the exposure energy of 345 J / m2. Figure 5 ^ As the exposure increases, the critical dimension value increases. In addition, the poly-supplied μ absorption was from 0.5 to 0.6 micrometers. Therefore, the half-tone phase & formula of the present invention can improve the process margin in the lithography process, and it is easier to automatically generate the mask layout in the mask data #. ^ ’

106l9twf.ptd Page 11 V. Explanation of the invention (8) According to the above embodiment, the mask is made with thick and thin ends at both ends and the middle is thin. The conventional method of staggered phase invention is relatively simple and convenient. Compared with the pattern of the pattern of ,,, and field, this fine pattern. In addition, the present invention can easily make a phase shift layer consisting of a thick middle and half-tone phase shift at both ends ^, and the f-phase shift type photomask uses a masking layer and a photomask to make the area more masked. Its simple structure is not only advantageous . b The resolution, contrast value, and manufacturing process of South Micro-film and the pattern formed by the interlaced phase-shift phase mask of the present invention and the half-phase phase-shifted light ... The effect of the critical size of the invention is small / = case, the duty ratio (Duty Rati) is not the same, this is the same; 2:! = =: The uniformity of the key size is better. Errors lead to reduced yield layers) to address the occurrence of conventional alignment problems. _, Ask, at the same time, can also reduce the manufacture of the photomask to limit the development of the preferred embodiment, as disclosed above, but it is not used within the scope, when it can be done ::: 'Although it does not depart from the spirit of the present invention, Relative " Please define the scope of the patent shall prevail.保 保 Compliance page 12 l06l9twf.ptd 200419303 Brief description of the diagram The first diagram is a schematic diagram of the edge gate conductor pattern; the second diagram is a schematic diagram of a binary photomask pattern; the second diagram is a diagram Figure 3A shows a schematic diagram of a phase-shift mask pattern. Figure 3A shows a top view of a half-tone phase-shift mask according to a preferred embodiment of the present invention. Sectional view of AA 'in the picture. Figure 3C shows the light intensity on the mask on the A_A' section in Figure 3A. Figure 3D shows the B_B 'on the 3A in Figure 3A. == H in FIG. M, the photomask of the cross section of the wafer during lithography is shown in FIG. 4A to FIG. 4B of the wafer. FIG. Good ... Use the fifth figure to show the relationship between the duty cycle and the key size. Figure 6 shows the relationship between the focal length of different exposure energies and the key size. The description of the beautiful labels: 2 0 0 ·-one-touch photomask 202, 212: transparent area 2 0 4: opaque area 210, 214 · Phase shift reticle 30 0: Half-tuned phase-shifted light army 302, 400: Base 10619twf.ptd Page 13 200419303 Brief description of the drawing 3 0 4: Half-tuned phase-shifted layer 3 0 6: Masking layer 30 8 : Pattern 3 1 0: light-transmitting area 4 0 2, 4 0 2 a: material layer 4 0 4: photoresist pattern

Wl, W2, W3, W4: width

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Claims (1)

200419303 6. Scope of patent application1. A half-modulation phase-shifting photomask includes: a photomask substrate; a half-modulation phase-shifting layer covering the surface of the photomask substrate, and the half-modulation phase-shifting layer presents a stripe And a masking layer 'covers both ends of the half-tone phase shift layer and exposes part of the half-tone phase shift layer' The width of the shield layer is greater than the width of the half-tone phase shift layer. 2. The half-tone phase-shifting photomask according to item 1 of the scope of patent application, wherein the material of the photomask base includes quartz glass. 3. The half-tone phase-shifting photomask according to item 1 of the scope of patent application, wherein the half-tone phase-shifting layer has a phase shift of 180 degrees. 4. The half-tone phase-shifting photomask according to item 1 in the scope of the patent application, wherein the material of the half-tone phase-shifting layer is selected from chromium oxynitride (CrON), chromium oxide (CrO), One of the groups consisting of nitrogen oxides (MoSizoxNy), amorphous carbon, and silicon nitride (SiN). 5. The half-tone phase-shifting photomask according to item 丨 of the patent application, wherein the half-tone phase-shifting layer has a transmittance of 4% to 10Q /. about. 6. The half-tone phase-shifting photomask as described in item 1 of the patent application, wherein the transmittance of the half-tone phase-shifting layer is about 6%. 7. The half-tone phase-shifting photomask according to item 1 of the scope of patent application, wherein the material of the shielding layer is chromium. 8. · A method for forming a pattern using a half-tone phase-shifting photomask, for forming a stripe pattern that is thick at both ends and thin in the middle, and the method includes: providing a substrate; 10619twf.ptd Page 15, the scope of the application for a patent forms a material layer on the substrate; forms a photoresist layer on the material layer; uses a half-tuned phase-shifting photomask to adjust the phase-shifting photomask includes: 〃 A dagger edge-blocking layer, wherein the half-mask base; a half-tone phase shift layer covering the half-tone phase shift layer of the mask in a stripe shape; and / : The width of the half-tone phase shift layer at both ends, and the width of the exposed layer; and the width of the layer far-shielding layer is larger than the half-tone phase shift interval, the photoresist defines the material, and forms-both ends of the middle and the middle The same: The pattern forming method using a half-tone phase shift photomask as described in item 8 of the Γ patent scope, wherein the material of the photomask base includes quartz glass.乂 1 10. The method for forming a pattern using a half-tone phase shift mask as described in item 8 of Shen Jing's patent scope, wherein the half-tone phase shift layer has a phase shift of 180 degrees. 1 1 · The method for forming a pattern using a half-tone phase shift photomask as described in item 8 of the scope of the patent application, wherein the material of the half-tone phase shift layer is selected from chromium oxynitride (CrON), chromium oxide ( Cr〇), molybdenum silicon oxynitride (MoSnNy), amorphous carbon and silicon nitride (Si N) is one of the groups. Z X 7 1 2 · The method for forming a pattern using a half-tone phase shift mask as described in item 8 of the scope of patent application, wherein the transmittance of the half-tone phase shift layer is 4 10619twf.ptd Page 16 200419303 6. The scope of patent application is about 10% to 10%. 1 3. The method for forming a pattern using a half-tone phase shift mask as described in item 8 of the scope of patent application, wherein the transmittance of the half-tone phase shift layer is about 6%. 1 4. The method for forming a pattern using a half-tone phase shift mask as described in item 8 of the scope of the patent application, wherein the material of the shielding layer is chromium. 1 5. The method for forming a pattern using a half-tone phase-shift mask as described in item 8 of the scope of the patent application, wherein the material of the material layer includes a conductive material. 1 6. The method for forming a pattern using a half-tone phase-shifting photomask as described in item 8 of the scope of patent application, wherein the material of the material layer includes a dielectric material. 10619twf.ptd Page 17