TWI222109B - Method of fabricating a titanium nitride layer - Google Patents

Abstract

A MOCVD is performed to form a titanium nitride layer on the surface of a semiconductor substrate. Following that, a pulsed plasma treatment is performed to remove hydro-carbon impurities from the titanium nitride layer. Therein, the pulsed plasma treatment is performed in a pressure chamber comprising nitrogen gas (N2), hydrogen gas (H2) or argon gas (Ar). A pressure of the pressure chamber is controlled to between 1 to 3 Torr, with the power of the pressure chamber controlled to between 500 and 1000 watts.

Description

1222109 V. Description of the invention (1) Field of the invention The present invention provides a method for making a titanium nitride layer, especially a method capable of reducing thermal budget and removing hydrocarbon impurities in the titanium nitride layer. ) Of a titanium nitride layer. BACKGROUND OF THE INVENTION In the current trend of semiconductor manufacturing processes, metal organic chemical vapor deposition has gradually replaced the traditional sputtering method and has been widely used in semiconductor manufacturing processes. It uses metal organic compounds to form thin films such as tungsten, aluminum, tantalum nitride (TaN), and titanium nitride on the surface of semiconductor substrates, and even bismuth osmium (BaSrTaOx, BST) Etc. ferroelectrics, thin films. However, this method is not without its shortcomings. For example, it is common practice to use a metal organic chemical vapor deposition method on the surface of a semiconductor substrate. The deposition of the carbon dioxide will generate some hydrocarbon impurities in the titanium nitride layer, which will affect the resistance value of the gold thin film.

= See Figure 1 and Figure 2. Figures 1 and 2 are half of the conventional techniques. F: L: A method of forming a titanium nitride layer. As shown in the figure, there are one or two semiconductor wafers 10, and the semiconductor wafer 10 is packaged with eight thunders. The bottom conductive layer 16 is located on the Shixi substrate 12; The electrical layer 18 is located on the bottom conductive layer 16 and is used as

Page 5 1222109 V. Description of the invention (2) Inter-metal dielectric (IMD), and a plurality of plug holes (p 1 ug ho 1 e) 2 0 (one is shown in the figure). Wherein, the bottom conductive layer 16 is an aluminum (A1) wire, and a surface of the aluminum wire is formed with titanium nitride,

TiN) anti-reflection coating (ARC) layer 1 7. Wherein, the plug hole 20 is prepared to form a tungsten (tungsten, W) plug in a subsequent process for electrically connecting the bottom conductive layer 16. In addition, the bottom conductive layer 16 may also be a gate, an electrode, or a source of a MOS transistor. As shown in FIG. 2, a metal organic chemical vapor deposition method is then used to deposit a titanium nitride layer 26 on the sidewall surface of the plug hole 20 as a barrier layer. The reaction formula is as follows:

Ti [N (CH3) 2], TiN (C, H) + HN (CH3) 2+ and other hydrocarbon impurities are as shown above. After the titanium nitride layer 26 is deposited, the metal organic chemical vapor deposition method also Some hydrocarbon-based impurities will be generated in the titanium nitride layer, and the hydrocarbon-based impurities will increase the resistance of the titanium nitride layer 26 and greatly reduce the uniformity of the product. Therefore, most of the current process technologies will use a plasma treatment to remove the hydrocarbon-based impurities existing in the nitride layer 26 after the metal organic chemical vapor deposition method is completed, and the titanium nitride layer 26 More dense

1222109 V. Description of Invention (3) (dense). However, there are some problems with this plasma treatment. Because the temperature of the silicon substrate 丨 2 will be heated by the plasma to above 40 ° C during the electropolymerization process, there are two bad phenomena: the first is the bottom conductive layer 16 The contained aluminum will be extruded (A1 extrusion) to the surface of the titanium nitride layer 26 f, so that the rc value after the tungsten plug is formed in the plug hole 20 is unstable. The second is the dielectric layer 18 (low dielectric The dielectric constant (internal metal dielectric layer) structure can be damaged. SUMMARY OF THE INVENTION Therefore, the main object of the present invention is to provide a method for reducing the thermal budget and forming a titanium nitride layer without impurities: [ties]. Another object of the present invention is to solve the problem that aluminum can be extruded. Another object of the present invention is to solve the problem that the structure of the inner metal dielectric layer with a low dielectric constant is damaged. In the preferred embodiment of the present invention, a metal nitride vapor deposition method (MOCVD) is used to form a nitride pre-layer on the surface of a semiconductor substrate, and then the titanium nitride layer is subjected to a pulse plasma treatment. (Pulsed plasma treatment) to remove hydrocarbon-based impurities in the titanium nitride layer. The pulsed plasma treatment is performed in a

1222109

5. Description of the invention (4) The pressure of nitrogen (NO, hydrogen (HD or argon) is grabbed, and the pressure range of the pressure is controlled between 1 and 3 torr, and the pulse type * The range of pulp processing power (power) is between 5000 and 1000 watts. The present invention can also use a cooler (chi 1 1 er) to control the crystal back cooling of the semiconductor substrate. Temperature, so that the temperature of the semiconductor substrate is reduced to less than 39 0 ° C for multiple plasma treatments to achieve the same effect. Element characteristics, can reduce the thermal budget, and can also achieve the purpose of removing hydrocarbon impurities. For a detailed description of the invention, please refer to FIG. 3 and FIG. 4, which are formed on a semiconductor wafer 50 according to the present invention. A schematic diagram of the method of the titanium nitride layer. As shown in FIG. 3, the semiconductor wafer 50 includes a stone substrate 52, a bottom conductive layer 56 is disposed on the surface of the stone substrate 52, and a dielectric layer 58 is disposed on the bottom conductive layer. Above 5 6 for low metal constant internal metal dielectric For the purpose of the layer, a plurality of plug holes 60 (only one is shown in FIG. 3) is provided in the dielectric layer 58. In the preferred embodiment of the present invention, the bottom conductive layer 5 6 is an aluminum wire, and An anti-reflection layer 57 made of titanium nitride is provided on the surface of the aluminum wire, and the plug hole 60 penetrates the dielectric layer 58 and the anti-reflection layer 57, and is ready to form a tungsten plug in the subsequent process. To electrically connect the bottom conductive layer 56.

Page 8 1222109 V. Description of the invention (5) As shown in Figure 4, a metal organic chemical gas is used to deposit and deposit a titanium nitride layer 6 6 on the surface of the plug hole 60 to serve as a barrier layer. Will be carried out in the metal organic chemical vapor deposition method with tetramethylamine. The (Tetrakis (Dimethylamino) Titanium, TDMAT) is used as a precursor, and the metal organic chemical vapor deposition method may further include nitrogen, hydrogen, or argon. The reaction equation of the gold organic chemical vapor deposition method is shown below "

Ti [N (CH3) 2] 4— TiN (C, H) + HN (CH3) 2+ Other hydrocarbon impurities As described above, after depositing the titanium nitride layer 66, the metal organic chemical vapor deposition The method also generates some hydrocarbon-based impurities in the titanium nitride layer 66, and the carbon-argon-based impurities increase the resistance of the titanium nitride layer 66. Therefore, in the present invention, after the titanium nitride layer 66 is deposited by using the metal organic chemical vapor deposition method, a pulse plasma treatment is performed immediately to remove impurities in the titanium nitride layer 66. In the preferred embodiment of the present invention, the pulsed plasma treatment is performed in a pressure chamber, so that the pressure range of the pressure chamber is controlled between 1 and 3 '. The processing power (ρ 〇wer) range is controlled at 5 Between 0 and 100 watts, and the pressure chamber contains reaction gases such as nitrogen, hydrogen or argon. Among them, the argon gas in the pulse plasma treatment is used to remove hydrocarbon impurities, hydrogen is used to remove the hydrocarbon impurities, and nitrogen is used to supplement the titanium nitride layer 66 which is removed by argon. Of nitrogen.

Page 9 1222109 V. Explanation of the invention (6)% When using the pulse plasma treatment to remove impurities in the titanium nitride layer 66, the processing power and gas flow rate of the pulse plasma treatment must be adjusted, that is, when The processing power is greater than 500 watt hours (between 500 and 丨 0 0 watts), and the gas flow of nitrogen and hydrogen must be controlled between 1 〇seem (standard cubic centimeter per minute) ~ 500 sccm . When the pulsed plasma processing power is less than 5,000 watts (between 0 and 5,000 watts), the gas flow rate of nitrogen and hydrogen must be controlled between 1000 seem ~ 3 0 0 seem In order to strengthen cooling (cooling) the semiconductor wafer 50, the temperature of the silicon substrate 52 is lower than 39 ° C. In other words, in order to solve the problem that the temperature of the silicon substrate 52 is too high as in the conventional technology, the pulse plasma processing of the present invention uses a time and power adjustment to obtain a pulse type The relationship between plasma treatment time (T) and temperature (t) is shown in Fig. 5. In the first stage of time T <, the processing power is greater than 500 watts (about 50 0 to 100 watts), and the temperature of the silicon substrate 52 is less than 390 ° C to remove hydrocarbon impurities; and in the second stage time TA, the processing power is reduced to less than 50 〇 Watts (between 0 and 5000 watts), and nitrogen and hydrogen are passed in to take away the hydrogen impurities and supplement the nitrogen removed by the argon in the titanium nitride layer 66, and it can also be cooled ( C 〇 1 ing) the semiconductor wafer 50, so that the temperature of the silicon substrate 52 can be lower than 390 t. Among them, the gas of nitrogen and hydrogen gas introduced in the first stage time T P

1222109 V. Description of the invention (7) The volume flow rate is controlled between 100 sccm and 50 sccm, and the gas flow rate of nitrogen and hydrogen gas introduced during the second stage of time T is controlled at 1000 mm ~ 3 0 0 0 seem; and the nitrogen and hydrogen gas passed in the third and fourth stages of time are equivalent to the nitrogen in the first stage of time and the second stage of time τ With the flow of hydrogen, the rest of Tn + and 1 \ + and so on. α Because the pulsed plasma treatment of the present invention can effectively maintain the silicon substrate 5 2 temperature below 39 ° C, without the conventional technology, allowing semiconductor wafers to be heated during plasma treatment. Above 42 0 ° C, it can reduce the thermal preheating to avoid damaging the internal metal dielectric layer with a low dielectric constant, that is, the structure of the dielectric layer 58, and complete the densification of the titanium nitride layer 66, while removing it Hydrocarbon-based impurities in the titanium nitride layer 66 increase the device performance. In addition, in the embodiment of the present invention, a cooler (ch i 1 er) may be installed in the pressure chamber to control the cooling temperature of the crystal back of the silicon substrate 5 2 to assist the pulsed plasma of the present invention. Treatment, so that the temperature of the silicon substrate 5 2 is slightly less than 390 ° C., to avoid problems caused by the temperature of the substrate 5 2 being too south. In the second embodiment of the present invention, a multi-step plasma treatment process is performed on the titanium nitride layer 66, and the temperature of the silicon substrate 52 is lower than the temperature of the silicon substrate 5 during the f and plasma processes. 39 ° C to remove hydrocarbon impurities in the Λ-nitride layer. That is, the second example of the present invention is a step of removing hydrocarbon impurities from the titanium nitride layer 66 using a continuous plasma treatment process. For example, first perform a first step on the titanium nitride layer 66.

Page 11 1222109 V. Description of the invention (8) A plasma treatment, and controlling the gas flow rate of nitrogen and hydrogen, so that the gas flow rate of nitrogen and hydrogen are between 100 sccm to 50 sccm, and when silicon When the temperature of the substrate 5 2 is close to 390 ° C, the first plasma treatment is stopped; and then the gas flow rates of nitrogen and hydrogen are controlled so that the gas flow rates of nitrogen and hydrogen are between 1 0 0 0 sccm ~ 3 0 0 〇sccm. Then when the temperature of the silicon substrate 52 drops to a safe temperature, adjust the flow of nitrogen and hydrogen to 100 see m ~ 500 seem, and then perform a second plasma treatment on the titanium nitride layer 66, and when the silicon substrate 5 When the temperature of 2 is close to 39 ° C., the second plasma treatment is stopped again. The above process is repeatedly performed to completely remove hydrocarbon impurities in the titanium nitride layer 66 and densify the titanium nitride layer 66. Similarly, in the second embodiment of the present invention, a pressure cooler (chi 1 1 er) may be additionally installed to assist the pulse plasma treatment of the present invention to reduce the temperature of the Shixi substrate 52. Compared with the conventional technology, the present invention is characterized in that in the stage where the processing power is less than 500 watts in the pulse plasma treatment and the multiple plasma treatments, the access is compared with the stage where the processing power is more than 500 watts. A larger amount of nitrogen and tritium gas is used to cool the temperature of the broken substrate, so that the temperature of the phenol substrate is constantly lower than 3 g 0 ° c, thereby avoiding the problems caused by the high temperature of the silicon substrate in the conventional technology. Only the preferred embodiments of the present invention are described. Range of application for patent made of modifications and alterations, also belong to the scope of the present invention patent.

Page 12122109 Brief Description of the Drawings Brief Description of the Figures Figures 1 and 2 are conventional techniques for forming a titanium nitride layer on a semiconductor wafer-Figures 3 and 4 are the invention on a semiconductor wafer Schematic diagram of the method for forming a titanium nitride layer on the top 0 Figure 5 is the relationship between the time and temperature of the pulsed plasma treatment of the present invention 〇 Symbols illustrated 10 Semiconductor wafer 12 Silicon substrate 16 Bottom conductive layer 17 Anti-reflection layer 18 Dielectric layer 20 Plug hole 26 Titanium nitride layer 50 Semiconductor wafer 52 Silicon substrate 56 Bottom conductive layer 57 Anti-reflection layer 58 Dielectric layer 60 Plug hole 66 Titanium nitride layer

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Claims (1)

1222109 VI. Scope of patent application 1. A method for fabricating a titanium nitride (TiN) layer on a semiconductor substrate, the method includes the following steps: providing a semiconductor substrate; utilizing a metal organic chemical vapor phase A deposition method (metal organic chemical vapor deposition (MOCVD)), forming the titanium nitride layer on the surface of the semiconductor substrate; and performing a pulsed plasma treatment on the titanium nitride layer to remove the titanium nitride Impurities in the layer. 2. The method according to item 1 of the patent application, wherein the metal organic chemical vapor deposition method (MOCCVD) is performed in an atmosphere containing TDMAT (tetrakis dimethyl amino titanium). 3. The method according to item 2 of the patent application, wherein the atmosphere environment further includes nitrogen (NO, hydrogen (d or argon (Ar)). 4. The method according to item 1 of the patent application, wherein the pulsed electric The plasma treatment is performed in a pressure chamber, and the pressure range of the pressure chamber is controlled between 1 and 3 torr. The pulse plasma treatment power (p0wer) ranges from 50 to 100 watts. 5. The method according to item 4 of the patent application scope, wherein the pressure chamber further comprises gas (n2) 'hydrogen (H2) or argon (Ar). Page 14 1222109 6. Application for Patent Scope 6. The method of the scope of patent application No. 5 in which the nitrogen (N 2) and the hydrogen (Η) are processed when the pulsed plasma processing power is greater than 500 Watts. 2) The gas flow rate is controlled between 100 seem (standard cubic centimeter per minute) to 500 sccm, and the temperature of the semiconductor substrate is lower than 3 900 ° C. 7. The method of the fifth item in the scope of patent application, where When the pulse plasma processing power is less than 500 watts, the gas flow rate of the nitrogen (N 2) and the hydrogen (氢气 2) is controlled between 100 sccm and 300 sccm. 8 · The method according to item 1 of the patent application range, wherein the pressure chamber includes a cooler (ch i 1 1 er) for controlling the cooling temperature of the back of the semiconductor substrate so that the temperature of the semiconductor substrate is slightly less than 3 9 0 ° C. 9. The method according to item 1 of the patent application, wherein the impurity in the titanium nitride layer is a hydrocarbon impurity and the hafnium nitride layer is used as a barrier layer ( barrier layer). 10. A method for removing hydro-car bon impurities in a titanium nitride (TiN) layer, the titanium nitride layer is formed by a metal organic chemical vapor deposition method (MOCVD) On a semiconductor substrate, the method includes the following steps: placing the semiconductor substrate in a pressure chamber; and performing a plurality of electropolymerization treatments on the titanium nitride layer (muti-step Page 15 1222109 6. Patent application (plasma treatment) process, and during the plasma treatment, the temperature of the semiconductor substrate is lower than 390 ° C to remove the hydrocarbons in the titanium nitride layer Impurities. 1 1. The method according to item 10 of the scope of patent application, wherein the pressure range of the pressure chamber is controlled between 1 and 3 torr, and each of the plasma processing power (ρ 〇wer) ranges is It is between 500 and 100 watts. 1 2. The method according to item 10 of the scope of patent application, wherein each of the plasma treatments is performed in an atmosphere containing nitrogen (N 2) and hydrogen (Η 2), and each of the plasma treatments is The method includes the following steps: controlling the gas flow rate of the nitrogen gas and the hydrogen gas (Η 2) so that the gas flow rates of the nitrogen gas and the hydrogen gas (Η 2) are between 100 seem and 500 seem respectively; Performing a plasma treatment, and stopping the plasma treatment when the temperature of the semiconductor substrate approaches 390 ° C; and controlling the gas flow rates of the nitrogen and the hydrogen (氢气 2) so that the nitrogen and the hydrogen (Η) 2) The gas flow is between 1000 seem ~ 3000 seem. 13 The method of claim 10, wherein the metal organic chemical vapor deposition method (MOCVD) is performed in an atmosphere containing TDMAT (tetrakis dimethyl amino titanium). Page 16 1222109 Page 17