TW594871B - Method of etching a metal line - Google Patents

Abstract

A method of etching a metal line. A substrate with a metal layer to be etched is provided, on which an amorphous carbon doped layer is formed over the metal layer by plasma enhanced chemical vapor deposition (PECVD). A resist layer is formed over the amorphous carbon doped layer, and the resist layer is patterned to define a resist mask. The amorphous carbon doped layer is etched to define a hardmask, the resist mask is stripped, and the metal layer not covered by the hardmask is etched to form a metal line for forming an interconnect.

Description

594871 V. Description of the invention (1) [Technical field to which the invention belongs] The present invention relates to a back-end process of a semiconductor wafer, and particularly relates to an amorphous carbon doped layer as a hard cover. Method for etching metal wires. [Prior art]

In the process of back end of 1 ine (BE0L) of a semiconductor wafer, a process of 'adding a metal system required to connect each element and each layer to the wafer' is called a metallization process. The metallization process described above includes forming a w / electric layer to cover a semiconductor substrate, planarizing and patterning the dielectric layer to form a trench and / or interlayer window, and filling the trench and / or interlayer®. To form wires and / or via plugs. A chemical mechanical polishing process is then performed to planarize the surface of the semiconductor substrate. The development of a semiconductor chip with a high degree of integration of electronic components and interconnects, small size, and powerful functions is an urgent task at present, which means that the interconnects described above need a line width of less than 0 · 18 nm (〇 · 18 // m ) Of metal wire. And design rules below 130 urn (0.13 // m)

The most critical factor in) is to define the analytical capability of the above metal wires in a lithographic process. The light source used in the lithography process below 130 nm (0.13 " m) is a deep ultraviolet laser with a wavelength of not more than 248 nm, and # 八 电 电 防 反 层 （dielectric anti-refiectiQn CQating DARC) and The combination of a thinner resist layer can effectively increase the small size control ability in the micro process, and can provide the required resolution

594871

However, the traditional combination is M, At t lithography process: = A1, Ti, and Ti ", and deep ... selectivity): too: the material's etching selectivity ratio (etch layer to etch metal wires is not enough) Use a thinner resist material alone :: T energy :: deposition-more able to withstand the remaining material etchins; RTF, the main X such as reactive ion etching (reactive i〇nr · in addition to its function, and Can provide better anti-reflective properties during patterning. Hard cover & beans in anti-cooking shovel ^ * 丨 丄 Hard dry materials 枓 'because the thin layer is deposited on the metal layer, and therefore can be described A gold resist mask patterned it. It is easier to use a thinner. [Summary of the Invention] Bismuth is here. The main purpose of the present invention is to provide an etching method, which is used in the semiconductor back-end process. A process for etching a metal wire or less. In order to achieve the above-mentioned object of the present invention, the method for etching a hairline includes the following steps: providing a base /, a metal conductor-metal hafnium; and forming a non-metal on the metal layer. Said: Zhishi J substrate with (amorphous carbon doped laye r); forming a resist layer on the above-mentioned θ; patterning the above-mentioned resist layer to determine ^ 2 said that the slave implanted layer is etched in the amorphous carbon implanted layer without the above-mentioned resist mask, agent mask ; Define a hard mask on the amorphous carbon implant layer; strip, σ 卩 of i, and the engraved resist mask that the metal layer is not covered by the hard mask; One

W4871

Metal wires. In order to make the above and other objects, features, and advantages of the present invention more comprehensible, a preferred embodiment is given below, and i is described in detail with the accompanying drawings as follows: [Embodiment] ^ Please refer to Section 1 Figures 8 to 8 are a series of cross-sectional views showing the steps of etching a metal layer by a process of 0 · 1 3 // m or less in the embodiment of the car body of the present invention. The etching method of the metal wire of the present invention includes forming an amorphous carbon doped layer as a hard mask to form a metal interconnect in the metal layer. Firstly, in the first figure, a substrate 100 with a component area (not shown in the drawing) is provided. The substrate 100 may moreover include an unfinished interconnect (not shown in the drawing) in Above the element area. Since the above-mentioned component area and unfinished interconnects are not important features of the present invention, they are not shown in the drawings for detailed description, so as not to lose focus when describing the present invention. A metal layer 110, for example, a metal layer having a stacked structure in which a Ti / TiN layer 110c is stacked on an A1 layer 110b, and an A1 layer 110b is stacked on a Ti / TiN layer 110a is deposited on the substrate 100. In the generation process of 0.18 Am or less, in the layered structure of the metal layer 110, the thickness of the Ti / TiN layer 110a is usually 200A to 1000A, and the thickness of the A1 layer 110b is generally 3000A to 8000 A. Ti / The thickness of the TiN layer 110c is usually 25 0 A to 100 A, and the A1 layer 110b usually further contains Cu at a concentration of about 0.5 weight percent. Next, refer to Figure 2 for plasma gain chemical vapor deposition

(plasma enhanced chemical vapor deposition; PECVD)

594871 V. Description of the invention (4) Method ′ An amorphous carbon implanted layer 12 having a thickness of 300 A to 100 A is formed on the metal layer 110. In the above PECVD method, a ^% gas is used as a precursor, and the & He gas is ionized with a radio frequency electric field having a frequency of 3 80 KHZ to 13.56 MHZ; at 300. At a temperature of 0 to 400 ° C, the ionized material was made; 5 carbon particles bombarded the metal layer 11 to form an amorphous carbon implanted layer 12 on the metal layer 11. Please note that the amorphous carbon implanted layer i 2 0 can also be used as an anti-reflection layer in the following patterning steps.

Next, please refer to FIG. 3, the resist layer 130 is formed on the amorphous carbon implantation layer 20 by a method such as a spin coating method. If necessary, an anti-reflection layer 36 may be formed on the top or bottom layer of the resist layer 130; the anti-reflection layer 136 may reduce the light reflection in the following patterning process together with the amorphous carbon implant layer 120. In a preferred embodiment of the present invention, the anti-reflection layer 36 is located on the bottom layer of the resist layer 130. Next, please refer to FIG. 4, pattern a resist layer with a light source having a wavelength of not more than 248 nm, for example, a deep ultraviolet laser beam, and form a resist layer opening 1 3 4 and form a resist cover. Act 丨 3 2. Among them, the resist mask 3 2 is used as a mask when the anti-reflection layer 1 36 and the amorphous carbon implant layer 2 200 are carved.

Next, referring to FIG. 5, an anti-reflection layer 136 and an amorphous carbon implant layer 丨 2 () are etched with an oxygen-containing plasma to etch the resist layer opening 134 to form a hard mask opening 1 24; The etched amorphous carbon implantation layer 20 becomes a hard mask 122, and is used as a hard mask when the metal layer 110 under the hard mask opening 124 that is not covered by the hard mask 122 is etched. Next, referring to Figure 6, peel off the resist mask 丨 32 to expose the hard mask 1 2 2.

594871 V. Description of the invention (5) Next, 'Please refer to FIG. 7, at a pressure of 10 to 150 πT, at a power of 100 watts and 1500 watts, and react with ion etching i oon etching; RIE), using oxygen ( 〇2), nitrogen (n2), or a fluorine-containing gas such as CF4 etches the portion of the metal layer 110 below the hard mask opening 124 without being covered by the hard mask 1 2 2. When the metal layer is etched, the anti-reflection layer 丨 3 6 is also removed ', and the hard mask layer 1 2 2 performs its function as an etching mask, and a line width of 0.13 / zm or less is predetermined. The pattern is transferred to the metal layer 11 and a metal wire 11 with a line width of 0.13 // m or less is formed. Please refer to FIG. 8, and ashing the hard mask 1 2 2 with oxygen to expose the metal layer 112. Compared with the conventional technology, the advantage of the present invention is that the line width of the metal wires can be reduced to form a high-density metal interconnect. The present invention can reduce the line width of the above-mentioned metal wire to less than 0.13, and achieves the above-mentioned main object of the present invention. ; Although the present invention has been disclosed as above with a preferred embodiment, it is not intended to limit the present invention. Any person skilled in this art, without departing from: the seed of the invention = and the scope, can make some changes and retouching, so The scope of the invention = shall be determined by the scope of the attached patent application. μ "

594871 Brief Description of Drawings Fig. 8 is a series of cross-sectional views showing the steps of etching a metal wire by a process of 0 · 1 3 // m or less in the preferred embodiment of the present invention. Symbol description I 0 0 ~ substrate; II 0 ~ metal layer; 110a ~ Ti / TiN layer; 110b ~ A1 layer; 110c ~ Ti / TiN layer; 11 2 ~ metal wire; 1 2 0 ~ amorphous carbon implant layer; 1 2 2 ~ hard mask; 1 3 0 ~ resist layer; 132 ~ resist mask; 1 3 6 ~ anti-reflection layer.

0702-9452twf (nl); 91Ρ54Π i dwwang.ptd page 11

Claims (1)

594871 6. Scope of patent application 1. A method for engraving a metal wire, including the following steps: providing a substrate having a metal layer; forming an amorphous carbon doped layer on the metal layer; A resist layer is formed on the amorphous broken implant layer; the resist layer is patterned to define / encapsulate the mask; at the moment, the portion of the amorphous carbon implant layer that is not covered by the resist mask is Defining a hard mask on the amorphous carbon implant layer; stripping the resist mask; and The part of the metal layer that is not covered by the hard cover is formed at a later time to form a metal wire. ~ 2 · The method of etching a metal wire according to item 1 of the scope of patent application 'further includes ashing (as h i n g) the hard mask after the metal wire is formed to expose the metal wire. 3. The method for etching a metal wire as described in item 1 of the scope of the patent application, wherein the metal layer further includes a first Ti / TiN layer, an A1 layer, and a second Ti / TiN layer, wherein the A1 layer is On the first Ti / TiN layer, and the second Ti / TiN layer is on the A1 layer. 4 · The method for etching a metal wire as described in item 3 of the scope of patent application, wherein the A1 layer further comprises _ Cu 〇5 with a concentration of approximately 0.5 weight percent. · As described in item 3 of the scope of patent application A method for etching a metal wire, wherein the thickness of the first Ti / TiN layer is 200A to 1000A, the thickness of the A1 layer is 3000A to 8000A, and the thickness of the second Ti / TiN layer is 250 594871 VI. Application for patent scope A ~ 100 0 A 6 · The method of engraving the metal wire described in item 1 of the declared patent scope 'where the thickness of the amorphous carbon implantation layer is 3 00a ~; [〇〇 〇A. 7. The method of engraving a metal wire as described in item 1 of the scope of patent application, further comprising forming an anti-reflection layer after forming the amorphous carbon implanted layer. 8 · The method of engraving a metal wire as described in item 1 of the scope of the patent application, wherein the resist mask is formed by patterning the resist layer with a light source having a wavelength of not more than 248 nm. 9 · A method for etching a metal wire, including the following steps: A substrate is provided. The substrate has a metal layer. The metal layer further includes a first Ti / TiN layer, an A1 layer, and a second Ti / TiN layer. The A1 layer is based on the first Ti / TiN. Layer, and the second Ti / TiN layer is on the A1 layer; an amorphous carbon doped layer is formed on the metal layer; a resist is formed on the amorphous carbon implanted layer Layer; patterning the resist layer to define a limiter mask; etching a portion of the amorphous carbon implant layer not covered by the resist mask and defining a hard mask on the amorphous barrier implant layer, Peel off the resist mask; _ etch the portion of the metal wire not covered by the hard wire I to form a metal wire; and ashing the hard mask to expose the metal wire. 1 0 · Etching method of metal wire as described in item 9 of the scope of patent application 0702-9452twf (nl); 91P54Π »dwwang.ptd No. 13 tribute 594871 Six, the scope of the patent application method 'wherein the thickness of the first layer is 200 and ~ 100, the thickness of the 81 layer is 3000 A to 8000a, and the thickness of the second Ti / TiN layer is 25 (A) to 10,000A 〇1 1 · > Etching of the metal wire as described in item 9 of the patent application The method, wherein the thickness of the amorphous carbon implantation layer is 300 A to 1000 A. It also includes the method of forming the amorphous tongue7. The method of etching the metal wire as described in item 9 of the scope of the patent application 13. If the resist layer is shaped to form I3, the scope of the patent application where the resist mask system After implanting the layer with crystalline carbon, an anti-reflection layer is formed. ^ The method of encircling the metal wire described in item 9 with a light source with a wavelength of 248 nm or less