TW440929B - Method for forming dielectric layer with a low dielectric constant - Google Patents

Abstract

The present invention discloses a method for forming dielectric layer with a low dielectric constant, which forms a black diamond film on a semiconductor substrate. The method comprises the steps of: using the chemical vapor phase deposition method to deposit a black diamond film on the semiconductor substrate; performing a stabilization process by immersing the semiconductor substrate into de-ionized water in a temperature range from 70 to 100 DEG C for 15 to 30 minutes, or immersing the semiconductor substrate into 5-20% hydrogen peroxide at the room temperature for 10 to 60 minutes; and finally placing the semiconductor substrate into a furnace and applying nitrogen at the temperature of 400 DEG C thereto for performing a curing process, thereby forming a cured black diamond film.

Description

440929 V. Description of the invention (i) Detailed description: Technical field: The present invention relates to a method for forming a dielectric layer with a low dielectric constant in an integrated circuit, and particularly to a method for forming a black diamond film as a low dielectric material. Method of constant dielectric layer β Background of the Invention: In order to pursue faster operating speed and greater integration density, research units and manufacturers of integrated circuits have endlessly devoted themselves to designing and manufacturing critical dimensions (CDs). Small components. According to experiments, when the integrated circuit manufacturing process enters the technical field of 0.1 8 microns or even 0.1 3 microns, the key factors affecting the speed of component operation have shifted from the width of the gate to the resistance of the metal interconnection- Capacitive hysteresis (RC delay) effect. Because the resistance value of a wire is inversely proportional to its cross-sectional area, as the accumulation density of the integrated circuit increases, the line width and thickness of the metal interconnects decrease, so the resistance value increases. In particular, With the increase of the integrated density of the integrated circuit, the line spacing of the metal interconnects is also reduced, thereby causing the coupling capacitance between the wires to increase. Therefore, when the manufacturing process of the integrated circuit enters the deep sub-micron field, the resistance-capacitance hysteresis of the metal interconnects is greatly improved, which also affects the operation rate and storage rate of the integrated circuit. In order to increase the accumulation density of the product circuit, under the condition that the line width and line spacing should not be increased, it is the best choice to replace the material of the metal interconnect and the interlayer dielectric layer. The original aluminum-silicon-copper alloy or Ming-steel alloy was replaced with copper metal.

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V. Description of the invention (2) The resistance to electron migration and good stress resistance, in addition to increasing the operation rate, can also improve the reliability of the component; in the other side, the interlayer dielectric layer must choose a low dielectric constant (Dielectric '

Constant) material to replace the original silicon dioxide to reduce the coupling capacitance between the gold connections. The dielectric constant of silicon dioxide is about 39, so a dielectric with a dielectric constant less than 3.9 must be selected as the interlayer dielectric layer to achieve the effect of reducing the resistance-capacitance hysteresis. For example: fluorine-doped Silicon dioxide (Si 0F), organic spin-on glass (HSQ), etc. In addition, an effective low-dielectric constant material is black diamond, which is formed by methyl silane (11 ^ 1; 11715113116). Its composition is 20% silicon, 30% oxygen, and carbon 9 %, Hydrogen 36%, and other elements. Because about 36% of the volume of black diamonds is pores, its dielectric constant is only about 2.9, which is a very low-dielectric constant material with great potential. In copper process technology, because copper metal cannot be engraved with gas like aluminum alloy, the industry has developed a damascene process method. For inlaying process technology, please refer to Motorola Corporation's Boeck;

"Method for manufacturing a low dielectric constant inter-level integrated circuit structure" disclosed by Bruce Allen et al. In U.S. Patent No. 588001 8. Please refer to FIG. 1, a first silicon nitride layer 11, a first low-k dielectric layer 12, a second silicon nitride layer 13, and a second low-dielectric layer are continuously formed on a semiconductor substrate 10 that has completed a previous process. The dielectric constant dielectric layer 14 is formed by two successive lithography and etching techniques, as shown in FIG. 1A. Next, please refer to Figure 1B. A layer of copper is formed by PVD, CVD, or electroplating.

Page 5 4 4092 9 V. Description of the invention (3) Membrane 16. Finally, as shown in FIG. 1C, the copper thin film 16 is polished by a chemical mechanical polishing method (CMP) to form a copper wire 17. Traditionally, when black diamond is selected as the low-k dielectric layer, the black diamond film deposition must be divided into three steps. The process flow chart shown in Figure 2 'Firstly, the black diamond film 21 is formed by chemical vapor deposition (CVD); then the semiconductor substrate is sent to the furnace tube' and oxygen is introduced at 200 ° C for stabilization. Process (stabilizati〇n) 22; Finally, the semiconductor substrate is sent into the furnace tube, and nitrogen is introduced at a temperature of 40 degrees Celsius to perform a curing process (cure) 23e. For 40 minutes in the tube, if the process of heating and cooling is added, it takes more than 2 hours, which not only reduces the output, but also increases the manufacturing cost (because the furnace tube is an expensive machine in the 1C waste) Because the stabilization process must be performed at a temperature of 200 degrees Celsius, the thermal budget of the process will also be increased. Therefore, a process to replace the stabilization process 22 has been developed to increase production, reduce manufacturing costs, And reducing the thermal budget has become an urgent problem to be solved in the semiconductor industry. SUMMARY OF THE INVENTION The main purpose of the present invention is to provide a method for forming a dielectric layer with a low dielectric constant. The present invention The method of β secondary objective is to provide a thin film formed as Black Diamond low-k dielectric layer

440929 V. Description of the invention (4) The present invention discloses a method for forming a dielectric layer with a low dielectric constant. A black diamond film is formed on a semiconductor substrate. The steps include: firstly, using a chemical vapor deposition method in the A black diamond film is deposited on the semiconductor substrate. Next, the stabilization process is performed. The semiconductor substrate is immersed in deionized water at 70 to 100 degrees Celsius for 15 to 30 minutes; or the semiconductor substrate is placed at 5-20% of room temperature. Soak in hydrogen peroxide for 10 to 60 minutes. Finally, the semiconductor substrate is put into a furnace tube, and nitrogen gas is introduced at a temperature of 400 degrees Celsius for 20 to 40 minutes to form a black diamond film. In the present invention, the soaking process of the cleaning tank is used instead of the high-temperature stabilization process of the conventional technique. Compared with the conventional technique, which needs to be performed in a furnace tube at 200 degrees Celsius, the process of the present invention requires less time, and the furnace tube is replaced by a cheaper two-tank process. The required low temperature can reduce the thermal budget of the product, increase the yield of the product, and compare the results of the dielectric properties of the black diamond film formed by the present invention and the results obtained from conventional techniques, which are revealed in the stabilization. The immersion process can indeed replace the conventional technique: J :: In addition, the flat energy band voltage control process obtained by the embodiments of the present invention. The absolute value of voltage) is much lower than that of conventional techniques. The at ~ band current (leakage current) greatly improves the low leakage of the component by adjusting the parameters of the immersion process of the present invention, such as immersion & ° / The external temperature and immersion time can be adjusted to form the love neck ^, the electrical constant 'is of great help to the design and application of components. Brief description of the film's media:

Page 7 t ::: '-Ο 9 P α V. Description of the invention (5) Figure 1A is a conventional double damascene process in which a first silicon nitride layer is successively formed on a semiconductor substrate that has completed the previous process. A schematic cross-sectional view of a process of forming a first low-k dielectric layer, a second silicon nitride layer, and a second low-k dielectric layer, and then using two successive lithography and etching techniques to form an opening. FIG. 1B is a schematic cross-sectional view of a process for forming a copper film in a conventional dual damascene process. FIG. 1C is a schematic cross-sectional view of a process for forming a copper wire by grinding the copper film by a chemical mechanical polishing method in a conventional dual damascene process. FIG. 2 is a flow chart of a process for forming a black diamond film in the conventional technology. Fig. 3 is a flow chart of a process for forming a black diamond film in the first embodiment of the present invention. Fig. 4 is a flow chart of a process for forming a black diamond film in the second embodiment of the present invention. Description of Drawing Numbers 10-Semiconductor substrate 1 First silicon nitride layer 12-First low dielectric constant dielectric layer 13-Second silicon nitride layer 14-Second low dielectric constant dielectric layer 1 5-Opening 1 6-copper film 1 7-copper wire

Page 8 44〇92 9 V. Description of the invention (6)-The present invention discloses a method for forming a dielectric layer with a low dielectric constant, in particular, a method for forming a black diamond film as a low dielectric constant dielectric layer Methods. The invention can be applied to copper processes of logic elements and memory elements of various types. Please refer to FIG. 3 for the manufacturing process circle of the first embodiment of the present invention. First, a black diamond thin cymbal 31 is formed by a chemical vapor deposition method; then, a semiconductor substrate is immersed in deionized water at 70 to 100 ° C. To 30 minutes 3 2; finally, the semiconductor substrate is sent into a furnace tube, and a gas is passed at a temperature of 400 degrees Celsius to perform a cure process 33.

Step 31 is performed by a plasma enhanced chemical vapor deposition method (pECVD) at a low temperature of 15 ° C to 20 ° C. In the soaking process of step 32, the best process parameter is to soak the semiconductor substrate in deionized water at 90 degrees Celsius for 20 minutes. In the curing process of step 33, the preferred process time is 20 to 40 minutes', and the optimal process time is about 30 minutes. In addition, the soaking process of step 32 in this embodiment may be changed to immersing the semiconductor substrate in deionized water at room temperature for 24 hours, which can achieve the same effect. Please refer to FIG. 4 for a process flow chart of the second embodiment of the present invention. First, a black diamond thin film 41 is formed by a chemical vapor deposition method; then the semiconductor substrate is immersed in hydrogen peroxide at room temperature for 0 to 60 minutes 42; finally, The semiconductor substrate is sent into a furnace tube, and nitrogen gas is passed at a temperature of 400 degrees Celsius to perform a curing process 43. Step 41 is performed by a plasma enhanced chemical vapor deposition method (pECVD) at a low temperature of 15 ° C to 20 ° C. Soak in step 4 2

Page 9 .440929 Five 'Invention description (7) In the process, the best process parameter is to soak the semiconductor substrate in 5 ~ 20% hydrogen peroxide at room temperature for 15 minutes. In the curing process of Step 4 3, the preferred process time is 20 to 40 minutes. The optimal process time is about 30 minutes. "From the above description and the processes in Figures 3 and 4, we can know that The invention replaces the high-temperature stabilization process of the conventional technique with the immersion process of the cleaning tank. Compared with the conventional technique, the stabilization process needs to be performed in a furnace tube at 200 degrees Celsius, which takes 2 hours before and after. The time is short, and several batches of wafers can be immersed at the same time, which greatly increases the output of the low dielectric constant thin film process; at the same time, because the furnace tube is a more expensive machine in the 1C block, the cost of the high-temperature furnace control process is very high. The invention replaces the stern tube with a cheaper cleaning tank process, which can greatly reduce the cost of the process; at the same time, the temperature required for the immersion process of the present invention is lower, which can reduce the thermal budget of the product, and improve the yield and reliability of the product. For comparison between the process results of the present invention and the process results of the conventional technique, please refer to the table for stabilizing the process, the dielectric constant, the flat band voltage, and the refractive index of the conventional technique. Example 2.99 -11.0 V 1.440 (90 ° C DI water immersion for 20 minutes) The second embodiment of the present invention 3.08 -1.9 V 1.429 (room temperature hydrogen peroxide soaked for 15 minutes) The second embodiment of the present invention 3.46 -0.5V 1.447 (room temperature hydrogen peroxide Soak for 60 minutes) Table 1

ΗΒΗ HI Page ίοο 9 2 9 V. Description of the invention (8) As shown in Table 1, the dielectric constant and refractive index obtained by the first and second embodiments of the present invention are both the results obtained by the conventional techniques Similarly, it is shown that the immersion process disclosed in the present invention can indeed replace the conventional high-temperature furnace control process in the stabilization process. In addition, the absolute value of the flat-band voltage obtained by the embodiments of the present invention is much lower than that of the conventional technology, a lower leakage current can be obtained, and the performance of the device is greatly improved. In addition, the present invention has a very important advantage. From the experiments in Table 1 and other experiments, it can be known that by adjusting the parameters of the immersion process of the present invention, such as immersion liquid, immersion temperature, and immersion time, the formed The dielectric constant of the black diamond film is of great help to the design and application of components. The above description uses the preferred embodiments to explain the present invention in detail, but not to limit the scope of the present invention, and those skilled in the art will also understand that making small changes and adjustments appropriately will still lose the essence of the present invention. Without departing from the spirit and scope of the invention.

Page 11 t '" 4 4 0 9 2 9 Brief description of the diagram Brief description of the diagram: Figure 1A is a conventional dual damascene process in which a first silicon nitride is continuously formed on a semiconductor substrate that has completed the previous process Layer, the first low-k dielectric layer, the second silicon nitride layer, and the second low-k dielectric layer, and then the process of forming an opening by two successive lithography and etching techniques is shown. FIG. 1B is a schematic cross-sectional view of a process for forming a copper film in a conventional dual damascene process. FIG. 1C is a schematic cross-sectional view of a process for forming a copper wire by grinding the copper film by a chemical mechanical polishing method in a conventional dual damascene process. FIG. 2 is a flow chart of a process for forming a black diamond film in the conventional technology. FIG. 3 is a flow chart of a process for forming a black diamond thin bead in the first embodiment of the present invention. Fig. 4 is a flow chart of a process for forming a black diamond film in the second embodiment of the present invention.

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Claims (1)

440 92 9 VI. Scope of patent application '1. " " " * A method for forming a dielectric layer with a low dielectric constant to form a thin film of chert on a semiconductor substrate, the steps include: a. Deposit a layer of obsidian thin film on the semiconductor substrate; b. Soak the semiconductor substrate in deionized water; and c. Place the semiconductor substrate in a furnace tube and pass nitrogen gas to perform a curing process ° 2. The method for forming a low-dielectric-constant dielectric layer as described in item 1 of the scope of the patent application, wherein the deposition step in step (a) is a chemical vapor deposition method. 3. The method for forming a dielectric layer with a low dielectric constant as described in item 1 of the scope of patent application, wherein the immersion step of step (b) is immersing the semiconductor substrate in deionized water at 70 to 100 degrees Celsius for 15 to 30 minutes. 4. The method for forming a low-dielectric-constant dielectric layer as described in item 1 of the scope of the patent application, wherein the immersion step of step (b) is performed by immersing the semiconductor substrate in deionized water at 90 ° C for 20 minutes. 5. The method of forming a dielectric layer with a low dielectric constant as described in item 1 of the scope of the patent application, wherein the immersion step of step (b) is a step of immersing the semiconductor substrate in deionized water at room temperature for 24 hours. 6. The method of forming a dielectric layer with a low dielectric constant as described in item 1 of the scope of the patent application, wherein the curing step of step (c) is to send the semiconductor substrate into a furnace tube at a temperature of 40 ° C. Blow in nitrogen for 20 to 40 minutes. 7. —Method for Forming Dielectric Layer with Low Dielectric Constant 'to form a black diamond film on a semiconductor substrate, the steps include: Page 13 440 92 9 VI. Application scope a. Deposition a black diamond film on the semiconductor substrate by chemical vapor deposition method; I b. Place the semiconductor substrate at a temperature of 70 ° to 100 ° C. Immersion in ion water for 15 to 30 minutes; and c. Placing the semiconductor substrate in a furnace tube, and passing nitrogen gas at a temperature of 40 degrees Celsius for 20 to 40 minutes. 8. A method of forming a dielectric layer with a low dielectric constant, forming a black diamond film on a semiconductor substrate, the steps include: a. Depositing a black diamond film on the semiconductor substrate; b. The semiconductor substrate is immersed in hydrogen peroxide water; and c. The semiconductor substrate is placed in a furnace tube, and nitrogen gas is passed through to perform a curing process. 9. The method for forming a low-dielectric-constant dielectric layer according to item 8 of the scope of the patent application, wherein the deposition step of step (a) is a chemical vapor deposition method. 10. The method for forming a low-dielectric-constant dielectric layer as described in item 8 of the scope of patent application, wherein the immersion step of step (b) is immersing the semiconductor substrate in 5 to 20% hydrogen peroxide at room temperature 1 0 to 60 minutes. 11. The method for forming a dielectric layer with a low dielectric constant as described in item 8 of the scope of the patent application, wherein the immersion step of step (b) is immersing the semiconductor substrate in 5 to 20% hydrogen peroxide at room temperature 1 5 minutes. 12. The method for forming a low dielectric constant dielectric layer as described in item 8 of the scope of patent application, wherein the immersion step of step (b) is a immersion of the semiconductor substrate in 5-20% hydrogen peroxide at room temperature for 60 minutes. . Page 14 4 40 92 9 VI. Patent Application Range 1 3. The method for forming a dielectric layer with a low dielectric constant as described in item 8 of the patent application range, wherein the curing step of step (c) is to send the semiconductor substrate Into the furnace tube, pass in nitrogen at a temperature of 40 degrees Celsius for 20 to 40 minutes. 14. A method of forming a dielectric layer with a low dielectric constant, forming a black diamond film on a semiconductor substrate, the steps comprising: a. Depositing a black diamond film on the semiconductor substrate by a chemical vapor deposition method; b. immerse the semiconductor substrate in 5-20% hydrogen peroxide at room temperature for 10 to 60 minutes; and c. place the semiconductor substrate in a furnace tube, and pass it at a temperature of 40 ° C Introduce nitrogen for 20 to 40 minutes.