BACKGROUND OF THE INVENTION
[1][0001] 1. Field of the Invention:
[2][0002] The invention relates generally to a method of manufacturing a copper wiring in a semiconductor device. More particularly, the present invention relates to a method of manufacturing a copper wiring in a semiconductor device capable of not only realizing reappearance of copper deposition process but also obtaining a thin copper film of a good film quality, by establishing the technology of metal organic chemical vapor deposition (MOCVD) process using 1,1,1,5,5,5- hexafluoro-2,4-pentadionato (3,3-dimethyl-l-butene)-copper(I) (hereinafter called “(hfac)Cu(DMB)” compound as a copper precursor.
[3][0003] 2. Description of the Prior Art:
[4][0004] As the semiconductor industry has moved toward ultra large-scale integration (ULSI), the geometry of devices has been continuously reduced to a sub-half-micron area while the circuit density in view of improvement of performance and reliability has increased. In order to meet these needs, in forming a metal wiring in a semiconductor device, a thin copper film can increase reliability of a semiconductor device due to a high electro-migration (EM) in copper film since it has a higher melting point than aluminum. Also, thin copper film can increase the signal transfer speed due to its low resistivity. Therefore, thin copper film has been employed as a useful interconnection material for integrated circuits.
[5][0005] In a method of manufacturing a copper wiring, a copper deposition process is useful for realizing higher-speed devices and higher-integration devices. The process employs various deposition methods such as a physical vapor deposition (PVD) method, an electroplating method, an electroless-plating method, a metal organic chemical vapor deposition (MOCVD) method. Of these copper deposition technologies, as the copper deposition by MOCVD method is significantly affected by a copper precursor, a copper precursor must be developed which can be easily deposited. Also, a delivery system capable of safely carrying this copper precursor must be necessarily developed.
[6][0006] Copper deposition by MOCVD method may employ a liquid delivery system (hereinafter called “LDS”) of a bubbler scheme, an LDS, such as a direct liquid injection (hereinafter called “DLI”) or an LDS, such as a control evaporation mixer (hereinafter called “CEM”). In addition, it may employ various LDSs, such as an LDS having a vaporizer of an orifice scheme or a spray scheme. Copper is deposited by dissolving compounds including a copper metal called a precursor in these LDSs. The copper precursor for use in MOCVD includes CuIIcompounds, such as a 1,1,1,5,5,5hexafluoro-2,4-pentadionato-copper(II); Cu(hfac)2 compounds having a low vapor pressure. After that, CuIcompounds have been developed which have a faster deposition speed due to high vapor pressure, compared to CuIIcompounds, thus allowing a thin copper film of a high purity to be deposited at low temperatures of 150 to 250° C.
[7][0007] Among CuIcompounds developed so far, 1,1,1, 5,5,5-hexafluoro-2, 4-pentadionato (trimethylvinylsilane)-copper(I) (hereinafter called “(hfac)Cu(TMVS)”) is a representative copper precursor for use in MOCVD. The compound is widely used since it exists at the liquid state at room temperature and allows a thin copper film of high purity to be deposited at a low temperature.
[8][0008] Even with these advantages, however, the (hfac)Cu(TMVS) compound has a problem in that it is degraded at high temperature and there is a difficulty in reappearance of the process when used in the process of manufacturing semiconductor devices. Also, though the vapor pressure of the (hfac)Cu(TMVS) compound is high among various precursors developed so far, it is rather low in securing appearance in a conventional LDS. Thus, there is a problem in securing reappearance as far as a new LDS capable of safely delivering a precursor. In addition, the (hfac)Cu(TMVS) has a problem that it must be kept at constant temperature since the difference between its vaporization temperature and its condensation temperature is narrow.
[9][0009] In order to solve problems associated with (hfac)Cu(TMVS), (hfac)Cu(DMB) has been developed as a precursor. (hfac)Cu(DMB) is a new compound which has been developed using 3,3-dimethyl-1-butene (hereinafter called “DMB”) as a Lewis base ligand. Since the DBM, having a low molecular weight and a high vapor pressure, is used as a Lewis base ligand instead of methyl group of TMVS, it has a higher vapor pressure than (hfac)Cu(TMVS). Therefore, the (hfac)Cu(DMB) compound is the most advantageous precursor since it can significantly improve a low deposition speed, which is one of the greatest problems in the MOCVD Cu precursor. However, the technology of MOCVD process using a (hfac)Cu(DMB) has not been established in a conventional LDS, nor commercialized.
SUMMARY OF THE INVENTION
[10][0010] The present invention provides a method of manufacturing a copper wiring in a semiconductor device capable of not only realizing reappearance of a copper deposition process but also obtaining a thin copper film having good film quality, by forming a chemical enhancer layer at the contact hole and the bottom of the trench and then selectively forming copper, using the technology of metal organic chemical vapor deposition (MOCVD) process using (hfac)Cu(DMB) compound as a copper precursor, without developing a new LDS.
[11][0011] A method of manufacturing a copper wiring in a semiconductor device according to the present invention comprises the steps of, after patterning a given region of an interlayer insulating film formed on a semiconductor substrate to form a damascene pattern, performing a cleaning process; forming a diffusion prevention film on the entire structure including the damascene pattern; forming a chemical enhancer layer on the surface of the diffusion prevention film; removing the chemical enhancer on the remaining portions except for the bottom portion of the damascene pattern, by performing immersion wet cleaning process and warm annealing process; forming a copper layer so that the damascene pattern can be filled; and polishing the copper layer to form a copper wiring.
BRIEF DESCRIPTION OF THE DRAWINGS
[12][0012] The aforementioned aspects and other features of the present invention will be explained in the following description, taken in conjunction with the accompanying drawings, wherein:
[13][0013]FIGS. 1a ˜1f are cross-sectional views for illustrating a method of manufacturing a copper wiring in a semiconductor device according to the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[14][0014] The present invention will be described in detail by way of a preferred embodiment with reference to accompanying drawings.
[15][0015] Referring now to FIG. 1a, a first insulating film 11, a first metal layer 12 and an interlayer insulating film 13 are sequentially formed on a semiconductor substrate 10 in which various components for forming a semiconductor device are formed. After a damascene pattern, consisting of a contact hole and a trench, is formed at the interlayer insulating film 13, a cleaning process is performed.
[16][0016] The interlayer insulating film 13 is formed using an insulating material having a low dielectric constant. The damascene pattern formed at the interlayer insulating film 13 is formed in a dual damascene pattern. The cleaning process employs RF plasma if the first metal layer 12 is W and Al, etc. If the first metal layer 12 is Cu, the cleaning process employs a reactive cleaning method.
[17][0017] Referring now to FIG. 1b, a diffusion prevention film 14 is formed on the entire structure including the sidewalls of the damascene pattern.
[18][0018] The diffusion prevention film 14 is formed of at least one of ionized PVD TiN, CVD TiN, MOCVD TiN, ionized PVD Ta, ionized PVD TaN, CVD Ta, CVD TaN, CVD WN, CVD TiAlN, CVD TiSiN and CVD.
[19][0019] Referring now to FIG. 1c, a chemical enhancer layer 15 is formed on the entire structure including the trench and the contact hole.
[20][0020] The chemical enhancer layer 15 is formed by chemically enhanced chemical vapor deposition (CECVD) using one of iodine (I)-containing liquid compound, Hhfacl/2H2O, Hhfac, TMVS, pure I2, iodine (I)-containing gas and water vapor as a catalyst, or using F, Cl, Br, I and At in a gaseous state of a liquid state which are group-7 elements in the periodical table or F, Cl, Br, I and At in a gaseous state of a liquid state which are group-7 element in the periodical table.
[21][0021] The CECVD process is performed for 1 to 600 seconds in the MOCVD equipment including a liquid delivery system (LDS) capable of delivering catalysts and their compounds in a liquid and gaseous state. As the CECVD process is performed at the temperature of between −20 and 300° C., the MOCVD equipment also performs the process at the temperature of between −20 to 300° C .
[22][0022] Referring now to FIG. 1d, after the chemical enhancer layer 15 is formed, in order to easily remove the chemical enhancer layer 15, immersion wet cleaning is performed using cleaning solution 16. Then, by performing warm annealing, the chemical enhancer layer 15 is removed from the surface of the interlayer insulating film 13 and remains only at the bottom portion of the damascene pattern.
[23][0023] The immersion wet cleaning is performed for 1 second to 5 minutes using any one of pure water (DI), DI+H2SO4, BOE and DI+HF as a cleaning solution. Also the immerse wet cleaning is performed at a temperature of between −20 and 50° C., using a spin rinsing method by which the semiconductor substrate 10 is immersed into the cleaning solution and is then rotated in the range of between 1 and 300 rpm. After the immerse wet cleaning process is performed, a warm annealing process is performed in order to remove any remaining cleaning solution 16. The warm annealing process is also performed at a temperature of between room temperature 1 and 200° C. while rotating the semiconductor substrate 10 at the rate of 1 and 2000 rpm in order to easily remove the any remaining cleaning solution 16.
[24][0024] Referring now to FIG. 1e, the internal portion of the damascene pattern is filled with Cu layer 17 by self-aligned growth process using MOCVD. This process easily fills the internal portion of the damascene pattern with Cu since deposition of Cu is concentrated on the portion at which chemical enhancer such as iodine, etc. used in the process shown in FIG. 1d is concentrated. Filling of Cu can be applied to all kinds of vaporizers such as DLI, CEM, orifice scheme and spray scheme, by use of all kinds of Cu precursors using hfac such as (hfac)CuV(TMOS) series, (hfac)Cu(DMB) series and (hfac)Cu(TMVS) series, etc. Cu is deposited using MOCVD using them.
[25][0025] In the above process, carrier gases employs any one of He, H2and Ar and the flow amount is in the range of between 100 and 700 sccm. At this time, the pressure within the reaction chamber is in the range of 0.5 and 5 Torr. The deposition temperature is in the range of between 50 and 300° C. and the distance between the showerhead within the copper deposition apparatus (not shown) and the susceptor plate is between 5 and 50 mm. In addition, the flow rate of the (hfac)Cu(DMB) compound, being a Cu precursor, is in the range of between 0.1 and 5.0 sccm. After the chemical enhancer is formed, aluminum or tungsten may be filled instead of copper.
[26][0026] Referring now to FIG. 1f, after copper is filled by MOCVD process, hydrogen reduction annealing process and chemical mechanical polishing (CMP) process are sequentially performed to remove the copper layer 17 remaining on the surface of the interlayer insulating film 13 and the diffusion prevention film 14 except for the internal portion of the damascene pattern, thus forming a copper wiring 17a.
[27][0027] The hydrogen reduction annealing process is performed under hydrogen reduction atmosphere at a temperature between room temperature and 450° C. for 1 minute to 3 minutes, thus changing a grain morphology. At this time, the hydrogen reduction atmosphere may use hydrogen (H2) only or hydrogen mixture gas such as H2+Ar(1-95%), H2+N2(1-95%), etc. After CMP process is performed, a pre-cleaning may be performed. The cleaning process and the process of forming a diffusion barrier may be performed with no time delay. Also, the copper plating process and hydrogen reduction annealing process may be performed with no time delay.
[28][0028] As mentioned above, the present invention facilitates filling of Cu into the dual damascene pattern even in the ultra-fine structure, by forming a chemical enhancer layer only in a contact hole and at the bottom of a trench by immersion wet cleaning process and warm annealing process and by growing copper by self-aligned growth process using MOCVD method. Therefore, the present invention has advantages that it can not only realize reappearance of copper deposition process but also obtain a thin copper film of a good film quality.
[29][0029] The present invention has been described with reference to a particular embodiment in connection with a particular application. Those having ordinary skill in the art and access to the teachings of the present invention will recognize additional modifications and applications within the scope thereof.
[30][0030] It is therefore intended by the appended claims to cover any and all such applications, modifications, and embodiments within the scope of the present invention.
