TW554083B - Method for electroless copper plating - Google Patents

Abstract

A method for electroless copper plating, suitable for semiconductor manufacture process. A semiconductor base surface is activated by contact displacement and then performed the electroless copper plating process at 60 DEG C to form a copper film on the activated surface of the semiconductor base. The electrolyte solution used in the electroless copper plating process comprises glyoxylic acid as reducing agent and further comprises copper ion source, complexing agent, stabilizing agent and surfactant.

Description

Case No. 554083 Case No. 88122467 Amendment V. Description of the Invention (1) The present invention relates to a method for manufacturing a semiconductor integrated circuit, and particularly to a method for performing electrodeless copper electrical bonding. In the IC industry, aluminum has been used as the material of metal wires for more than 30 years. However, as the requirements for the integration degree and operating speed of semiconductor integrated circuits have continued to increase, many characteristics of metal wires in integrated circuits , Such as resistivity, stability, and ability to resist electromigration (E 1 ectr 〇migra ΐ i ο η) also need to be greatly improved. However, due to the limitation of the nature of aluminum, aluminum metal wires cannot meet this demand. Especially when the semiconductor process enters the deep sub-micron generation, it has become a trend to use a material with better properties than aluminum as the metal wire. When the IC company announced the successful development of copper process technology in September 1997, and will replace the aluminum wire of the integrated circuit process, the IC industry has actively invested in the research of copper process using copper as the metal wire. This is because copper itself has low resistance, stability, reduced porosity caused by stress, and excellent resistance to electromigration. Therefore, using copper as a metal wire is very suitable for deep submicron semiconductor processes. Conventional methods for making copper metal wires are mostly made by methods such as chemical vapor deposition (CVD), physical vapor deposition (PVD), or electrode ore. Among these methods, the chemical vapor deposition method and the physical vapor deposition method have a relatively high process temperature, are expensive, and have poor hole filling ability, and the electrode plating method is not suitable for mass production except for an additional power source. Therefore, it has become an urgent need in the IC industry to provide copper wires with a simple process, low cost, good hole filling ability, low process temperature, and industrial applicability.

5955 twf2.ptc Page 9 554083 _ Case No. 88122467_ Year Month Revision _ 5. Description of the invention (2) Therefore, one of the objects of the present invention is to provide a method with simple process, low cost, low process temperature and industrial applicability. Method for making copper metal wires. Another object of the present invention is to provide a method for forming a copper film. This method can form a copper film on a semiconductor substrate having an opening, and completely fill the opening of the semiconductor substrate without causing voids. Another object of the present invention is to provide a plating solution formulation. The formulation of this plating solution is suitable for electrodeless copper plating technology, and by using this plating solution formulation, a copper film with good quality and good hole filling ability can be formed. Another object of the present invention is to provide a method for electrodeless copper plating. This method first activates the surface of a semiconductor substrate to form a copper film by contact replacement (C ntact D isp 1 acement), and then immerses this semiconductor substrate ® with g 1 y ο X y 1 icacid as a reduction Agent, and a plating solution containing a copper ion source, a complexing agent, a stabilizing agent, and a surfactant, etc., to perform electrodeless copper electromineralization to form a copper film on a semiconductor substrate and fill the opening of the semiconductor substrate to Make a copper metal wire. In order to make the above-mentioned objects, features, and advantages of the present invention more comprehensible, the following exemplifies preferred embodiments and describes them in detail with the accompanying drawings as follows: For an embodiment, please refer to FIG. 1. First, a semiconductor is provided. The substrate 14 and the semiconductor substrate 14 are composed of the substrate 10 and an oxide layer 12 above the substrate 10. Among them, the material of the φ substrate 10 is, for example, a silicon substrate with a crystallizing direction of (100), and the oxide layer 12 is, for example, silicon dioxide. The oxide layer 12 has an opening 16, and the opening 16 exposes a part of the substrate 10. Next, a conformal with the semiconductor substrate 14 is formed.

5955twf2.ptc Page 10 554083 _Case No. 88122467_ Year Month__ V. Description of the invention (3) (C ο nf 〇rma 1) The adhesive layer 18 covers the bottom and side walls of the opening 16 and the oxide layer 1 2 Above it, a barrier layer 20 conforming to the adhesive layer 18 is formed to cover the adhesive layer 18. Among them, the main function of the adhesive layer 18 is to increase the adhesion between the barrier layer 20 and the oxide layer 12. The material of the adhesive layer 18 is, for example, titanium metal (Ti), titanium nitride (TiN), tantalum metal. (Ta) or nitride button (TaN). The main function of the barrier layer 20 is to prevent the subsequently deposited metallic copper (shown in Figure 3) from diffusing into the oxide layer 12 to avoid the failure of the oxide layer 12 and the short circuit of the entire integrated circuit. The material of the barrier layer 20 is, for example, titanium nitride (T i N), titanium metal (T i), button metal (T a), titanium silicide (T i S i), or nitrogen silicide button (T a S i N) and other substances. In addition, an amorphous silicon layer (Amorphous Si) 14a may be formed on the surface of the barrier layer 20 of the semiconductor substrate 14, and then the following steps may be performed. Referring to FIG. 2, a contact replacement method is performed to form a replacement film 22 on the surface of the barrier layer 20 or the amorphous silicon layer 1 4 a. The method of performing the contact replacement method is, for example, immersing the semiconductor substrate 14 having the adhesive layer 18, the barrier layer 20, and the amorphous silicon layer 14a in the contact replacement solution for about 15 seconds, and then Remove and wash with secondary deionized water. Among them, the contact replacement solution (100 ml) is, for example, a solution having components such as CuS04.5H20, HF, and Triton X-114. The concentration of Cu S 0 4 · 5 Η 20 is about 0.025 M, the concentration of H F is about 1 M, and the amount of T r i t ο η X-1 1 4 is about one drop. The reaction equation that takes place is as follows:

Si + 6F '+ 2Cu2 +-2Cu + SiF62- Since the contact replacement method is to immerse the semiconductor substrate in a solution containing copper ions, the material of the replacement layer 22 can be metallic copper. The main purpose of this replacement layer 2 2 is to activate the semiconductor substrate 1 4 which has formed the barrier layer 20.

5955twf2.ptc Page 11 554083 _Case No. 88122467_Year Month and Day_ί ± ^ __ 5. Description of the invention (4) Surface. In this way, the quality and uniformity of the copper film 2 4 (illustrated in FIG. 3) formed by the electrodeless copper plating method in the following can be beneficial. Referring to Fig. 3, the replacement layer 2 2 (shown in Fig. 2) is replaced with a copper layer 2 4 conforming to the semiconductor substrate 14 by an electrodeless copper plating technique. The method for manufacturing the copper layer 24 is, for example, immersing the semiconductor substrate 14 on which the replacement layer 22 has been formed in a non-electrode copper plating solution at a temperature of about 60 ° C for about 4 minutes, and then immersing the semiconductor substrate Remove it, rinse it with deionized water twice, and blow dry with nitrogen. Among them, the components of the electrodeless copper bond solution are CuS04 · 5 H20, glycoxylic acid, EDTA, 2, 2'-dipyridyl, TMAH (Tetra Methyl Ammonium Hydroxide), and Triton X-114, and the concentration of each component is divided into As described later: CuS04 * 5H20 is about 0.035M, glycoxylic acid is about 0.08M, EDTA is about 0.06M, 2,2'-dipyridyl is about 100ppm, and the amount of T rit ο η X-1 1 4 It is related to the amount of the entire electrodeless copper electroplating solution. Taking the electrodeless copper electric clock solution as 200 in L as an example, T rit ο η X-1 1 4. It takes about two drops. The role of TMAA is mainly to adjust the pH value of the entire electrodeless copper plating solution to about 12.5. In this electrodeless copper plating solution, CuS04 · 5H20 is used as a source of Cu ions, g 1 y ο X y 1 icacid is used as a reducing agent, and EDTA is used as a complexing agent, which functions to enhance the effect of replacing the replacement layer 2 2 , And T rit ο η X-1 1 4 is used as a surfactant. It is worth mentioning that because g 1 y χ y 1 i c a c i d is a non-toxic substance, the use of g 1 y χ y 1 i c a c i d as a reducing agent in the electrodeless copper plating solution can greatly reduce the danger and pollution of the entire process. The use of T M A Η to adjust the p Η value of the electrodeless copper plating solution can avoid the contamination of the entire process by sodium and potassium ions.

5955twf2.ptc Page 12 554083 _Case No. 88122467_ Year Month Revision _ 5. Description of the invention (5) Please refer to FIG. 4, which shows the replacement layer 2 2 including this embodiment (shown in FIG. 2) A scanning electron microscope image of a semiconductor substrate that was replaced with a copper layer by electroless copper plating for 4 minutes. It can be known that the copper film can be continuously grown on the surface of activated amorphous silicon by electrodeless copper plating. In contrast, please refer to FIG. 5, which shows a scanning electron microscope image of a conventional copper layer directly formed on the surface of the barrier layer without a replacement layer. It can be seen that the copper island structure is distributed on the surface of the barrier layer, so the island structure is dispersed and not dense, which is not conducive to the subsequent growth of the copper film. Since the contact replacement method of the present invention can effectively activate the surface of a semiconductor substrate to be formed with a copper layer, and improve the quality of the formed copper layer and the ability to fill holes, the formula of the electrodeless copper electric bond liquid used in the present invention has low The invention has the advantages of pollution, high safety, and relatively simple added substances. Therefore, the present invention has the advantages of simple process, low cost, good hole filling ability, low process temperature, and the like, and is also extremely valuable in industrial applicability. In summary, although the present invention has been disclosed in the preferred embodiment as above, it is not intended to limit the present invention. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Retouching, therefore, the scope of protection of the present invention should be defined by the scope of the attached patent application.

5955 twf2.pt c Page 13 554083 Case No. 88122467 is a simple explanation of the modified diagram: Figure 1 shows a schematic cross-sectional view of a general semiconductor wafer, and Figure 2 shows the activation of a semiconductor using the contact replacement method of the present invention A schematic cross-sectional view of a substrate surface. FIG. 3 illustrates a cross-sectional view of electrodeless copper plating on the surface of an activated semiconductor substrate using the method of the present invention, and FIG. 4 illustrates a semiconductor substrate including a replacement layer according to this embodiment. The material was subjected to electrodeless copper electroplating technology for 4 minutes. It was replaced by a scanning electron microscope image of a copper layer, and Figure 5 shows a scanning electron microscope image of a conventional copper layer directly formed on the surface of a barrier layer without a replacement layer. . Description of reference numerals: 10 substrate 12 oxide layer 14 semiconductor substrate 14a: amorphous silicon layer 16 opening 18 adhesive layer 20 barrier layer 22 replacement layer 24 copper layer

5955twf2.ptc Page 14

Claims (1)

55406 Case 1122467 said the scope of the patent application for amendment six Γ ...-1 · A method of electrodeless copper electroplating, which is suitable for use in semiconductor processes, wherein the method includes: providing a semiconductor substrate, wherein the semiconductor substrate includes a substrate and above An oxide layer, wherein the oxide layer has an opening, and the opening exposes a part of the surface of the substrate; forming an adhesive layer, wherein the adhesive layer conforms to the semiconductor substrate and covers the bottom and sidewalls of the opening; and On the oxide layer; forming a barrier layer, wherein the barrier layer is conformal with the adhesive layer and covers the adhesive layer, and the adhesion between the barrier layer and the oxide layer is through the adhesive layer Being added; forming a replacement layer to activate the surface of the semiconductor substrate on which the barrier layer has been formed, wherein the replacement layer covers the barrier layer and is conformal with the barrier layer; and An electrodeless copper plating step to replace the replacement layer with a copper layer. 2. The method of electrodeless copper electroplating according to item 1 of the scope of patent application, wherein the method further comprises forming an amorphous silicon layer to cover the surface of the semiconductor substrate before forming the replacement layer. 3. The method of electrodeless copper electrical bond as described in item 1 of the scope of patent application, wherein the method of forming the replacement layer comprises immersing the semiconductor substrate in a contact replacement solution after forming the adhesive layer for about 1 5 Seconds, take it out and wash it with twice deionized water. 4. The method of electrodeless copper electroplating as described in item 3 of the scope of patent application, wherein the contact replacement solution includes a copper ion source and a fluoride ion source 5955twf2.ptc Page 15 554083 _Case No. 88122467_Year Month__ Sixth, the scope of patent application and a surfactant. 5. The method of electrodeless copper plating as described in item 4 of the scope of patent application, wherein the copper ion source comprises CuS04o5H20. 6. The method of electrodeless copper plating as described in item 5 of the scope of patent application, wherein the concentration of CuS04o5H20 in the contact replacement solution is approximately between (K 0 0 5 Μ and (L 5 Μ). The method of electrodeless copper electroplating according to item 6 of the patent scope, wherein the optimal concentration of CuS04o5H20 in the contact replacement solution is between about 0.01 Μ to 0.04 Μ. The method of electrodeless copper electroplating according to item 4, wherein the fluoride ion source in the contact replacement solution includes HF. 9. The method of electrodeless copper electroplating according to item 8 of the patent application scope, wherein the contact replacement solution The concentration of HF in the solution is between about 0.01M and 10M. 10. The method of electrodeless copper plating as described in item 9 of the scope of the patent application, wherein the optimal concentration of HF in the contact displacement solution is about 0. 8 M to 1.2 M. 1 1. The method of electrodeless copper electroplating as described in item 4 of the patent application scope, wherein the surfactant in the contact replacement solution includes T rit η η X- 1 1 4 ° 1 2 .The electrodeless copper plating Method, wherein the concentration of the T rit η X-1 1 4 in the contact replacement solution is approximately 100 drops of T rit ο η X-1 1 4 in the 100 ml of the contact replacement solution. The method of electrodeless copper electroplating according to item 3 of the patent scope, wherein the method of forming the adhesive layer includes performing at room temperature. 5955twf2.ptc Page 16 554083 Case No. 88122467_ Year, month, day, and date of the amendments to the description of the electroplated copper electrode without electricity r--I Fan Li, please Fan Zhongli in the middle? 4 Please 1 Â € ¢ Titanium cyanide nitrogen covers the material. A layer of obstacles in the barrier, the button Sinochem silicon, gas method and titanium, including a package of high quality materials, monographs, please apply. Shi Zhongyi LO, one of them, the buttoned nitrogen of the copper plating electrode in the Chinese and French side, and the step of plating with the button titanium nitride to cover the method ^ tio The application should be applied as described in Chinese 6 and 11 methods of copper plated electrode. None of the above items ^ ¾ None 1 Replace the layer with the base material of the immersion material. Change the layer. Take this gas out of the nitrogen and take the washed water 0 times. If the strontium is used to blow electricity, please apply for the source of copper. Please apply for this source; If the neutron agent is used to remove the ion, the copper is still wrong. : Including the 16-item sub-item that is included in the sub-item, there is no way to plate and adjust the electricity. The copper electrode is included in the sub-item. and. Dedicated electricity Please do not use the agent, the nature of the agent is assured that the surface is 0. Its safety boundary 1, one by one method of electroplated copper electrode. Of ο 2. Describe 5Η5 premises 40 items y S dagger 7 U / 1 1 C Enclosed value range source PH Lizi's special separation liquid Please copper plating this electricity as medium Copper g 5955twf2.pt c page 17 554083 _ case number 88122467_ year month date _ amendment _ 6, the scope of patent application 20 0 · the method of electrodeless copper electricity ore as described in the scope of patent application item 19, wherein the copper ion The concentration of the source includes between 0.005 M and 0.5 M. 2 1. The method of electrodeless copper electroplating as described in item 20 of the scope of the patent application, wherein the optimal concentration range of the copper ion source includes between 0.002 M and 0.05 M. 2 2 · The method of electrodeless copper electrical bond as described in item 17 of Shen Qing Patent Scope, wherein the reducing agent includes g 1 y ο X y 1 i c a c i d. 2 3. The method of electrodeless copper electroplating as described in item 22 of the scope of the patent application, wherein the concentration of the reducing agent includes between 0.01 M and 1 M. 24. The method of electrodeless copper electroplating according to item 23 of the scope of the patent application, wherein the optimal concentration range of the reducing agent includes between 0.075 Μ and 0.95 Μ. 25. The method of electrodeless copper plating as described in item 17 of the scope of patent application, wherein the complexing agent includes EDTA. 26. The method of electrodeless copper electroplating as described in item 25 of the scope of the patent application, wherein the concentration of the complexing agent includes between 0.05 M and 0.5 M. 04M 至 0. 08Μ 之间。 2 7. The method of electrodeless copper electroplating as described in item 26 of the patent application range, wherein the optimal concentration range of the complexing agent includes between 0.04M to 0.08M. 2 8. The method of electrodeless copper electroplating as described in item 17 of the scope of patent application, wherein the stabilizer comprises 2,2'-d i p y r i d y 1. 29. The method of electrodeless copper plating as described in item 28 of the scope of patent application, wherein the concentration of the stabilizer is about 100 ppm. 30. The method of electrodeless copper plating as described in item 18 of the scope of patent application 5955twf2.ptc Page 18 554083 Amendment No. 88122467 々, Patent Application Law, where the compound used to adjust the ρ Η value of the electroless copper plating solution includes TEA Μ ° 3 1 According to the method for electrodeless copper electro-ore, the pH value of the electroless copper electroplating solution includes between 12 and 13. 3 2 · The method of electrodeless copper electrical bonding as described in item 17 of the scope of patent application, wherein the temperature at which the electrodeless copper plating step is performed is included at 60 ° C. 3 3 · The method of electrodeless copper plating as described in item 18 of the scope of patent application, wherein the optimal temperature for performing the electrodeless copper plating step includes between 5 5 ° C and 65 ° C. 5955 twf2.pt c p. 19 ^ 19, Lane 216, Mingshing Rd., Judung Jen, (Cuili u > Taiwan 310 (Emck Chemical Technology Co., Ltd. claim or name 3 texts) Merck-Kanto Advanced Chemical Ltd Applicants (1 person) 3rd Floor, No. 34, Minquan West Road, ROC Koubei, ROC (This address is the same as the applicant from the previous office) _ 3F1 ·, No · 34, Minchiuan W. Rd., Taipei, Taiwan 103, R. 0. C. Lai Chao