Method for depositing low-roughness silicon dioxide film on carbon-containing film layer
By forming an isolation layer on the carbon-containing film layer and controlling the flow ratio of silane and oxygen, the problem of high roughness of the silica film layer when growing on the carbon-containing film layer is solved, and the growth of the low-roughness silica film layer is achieved, which significantly reduces the surface roughness of the film layer.
Patent Information
- Application Number
- CN202411976449.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2025-05-06
AI Technical Summary
Growing a low-rough silicon dioxide film layer on the carbon-containing film layer becomes difficult because the precursor oxygen of the silica reacts with the carbon-containing film layer to generate carbon dioxide, resulting in surface etching of the film layer and high roughness.
By forming an isolation layer on the carbon-containing film layer, using the flow ratio control of silane and oxygen, a mixture of silicon monoxide and silica is formed as an isolation layer to isolate the reaction between oxygen and the carbon-containing film layer, avoid oxidation and erosion, and then increase the oxygen flow to oxidize the isolation layer into a silicon dioxide film layer.
The surface roughness of the silica film layer is significantly reduced, which is 58.3% lower than conventional methods, ensuring the flatness and denseness of the film layer.
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Figure CN119932524A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of semiconductor film layer deposition, and in particular relates to a method for depositing a low-roughness silicon dioxide film on a carbon-containing film layer. Background Art
[0002] With the continuous development of integrated circuit technology, more and more metal layers are introduced into the semiconductor manufacturing process. Metals have strong diffusion capabilities and can diffuse into masks and silicon substrates more easily. Since metals have excellent conductivity, the diffusion of metals in the substrate structure will cause serious leakage problems, which will seriously affect the performance and power consumption of the entire circuit system. Silicon dioxide, as a film layer with good density and almost no pollution during growth, not only has good insulation properties, but also can act as a barrier layer to prevent the upper metal from diffusing downward. It is widely used in the manufacture of various process stages of integrated circuits. Therefore, using silicon dioxide as an isolation layer for the metal layer is a common choice.
[0003] However, if you want to grow a low-roughness silicon dioxide isolation layer on a film layer containing carbon elements, for example, on a hard mask layer or ARC layer such as SOC (Spin On Carbon), SOH (Spin On Hardmask), ACL (Amorphous Carbon Layer), it will become extremely difficult to grow a low-roughness silicon dioxide film layer. The reason is that the precursor oxygen used in the growth of silicon dioxide will react with the film layer containing carbon elements to generate carbon dioxide, causing the surface of the film layer to be etched, causing the surface to become uneven during the growth of silicon dioxide, resulting in a high roughness of the silicon dioxide film layer. Therefore, a new method for growing silicon dioxide film layers is needed, which allows silicon dioxide to grow on a film layer containing carbon elements and has a low roughness after the growth is completed. Summary of the invention
[0004] The object of the present invention is to provide a method for depositing a low-roughness silicon dioxide film on a carbon-containing film layer, aiming to solve the above-mentioned problems.
[0005] The present invention is mainly achieved through the following technical solutions:
[0006] A method for depositing a low-roughness silicon dioxide film on a carbon-containing film layer comprises the following steps:
[0007] Step S1: generating an isolation layer on the carbon-containing film layer: placing the carbon-containing film layer in a reaction chamber, first introducing silane into the reaction chamber, and then introducing oxygen, wherein the flow ratio of oxygen to silane is 0.125-0.16:1, setting the power of the plasma generator to 150W, and generating an isolation layer on the carbon-containing film layer;
[0008] Step S2: generating a silicon dioxide film layer of target thickness on the carbon-containing film layer based on the isolation layer: increasing the flow rate of oxygen, and the flow rate ratio of oxygen to silane is greater than 0.19, while continuously generating silicon dioxide on the isolation layer, promoting the isolation layer to be oxidized into a silicon dioxide film layer.
[0009] In order to better implement the present invention, further, in the step S1, the flow rate of silane is 60-64 sccm, and the flow rate of oxygen is 8-10 sccm.
[0010] In order to better implement the present invention, further, in step S2, the flow rate of oxygen is 13-16 sccm.
[0011] In order to better implement the present invention, further, in the step S1, the temperature of the reaction chamber is first gradually increased to 130° C., and while standing to keep the temperature, silane is introduced into the rear of the reaction chamber.
[0012] In order to better implement the present invention, further, in step S1, while oxygen is introduced, the pressure of the reaction chamber is controlled to 1.5 Pa.
[0013] In order to better implement the present invention, further, in step S2, the flow ratio of oxygen to silane is 0.2-0.26:1.
[0014] In order to better realize the present invention, further, it is applied to generate a silicon dioxide film with a thickness of 10-40nm, comprising the following steps:
[0015] Step A1: After placing a wafer having a carbon film layer on its surface into a reaction chamber, gradually heating the reaction chamber from room temperature to 130° C., and then keeping the temperature for 30-90 seconds to ensure that the entire wafer has a uniform temperature distribution; during the heat preservation process, silane is introduced into the reaction chamber at a flow rate of 60-64 sccm;
[0016] Step A2: After heat preservation, oxygen is introduced into the reaction chamber at a flow rate of 8-10 sccm, and the pressure in the reaction chamber is stabilized at 1.5 Pa, and the power of the plasma generator is set to 150 W, and the reaction is carried out for 15-60 seconds to form an isolation layer on the carbon-containing film layer;
[0017] Step A3: Then, the flow rate of oxygen is increased to 13-16 sccm, so that the flow rate ratio of oxygen to silane is greater than 0.19, so as to form a silicon dioxide film layer on the isolation layer and promote the isolation layer to be oxidized into a silicon dioxide film layer.
[0018] In order to better implement the present invention, further, in the step A3, the reaction is carried out for 80 seconds, and finally a silicon dioxide film layer with a thickness of 20 nm is generated on the carbon-containing film layer.
[0019] The beneficial effects of the present invention are as follows:
[0020] The present invention reduces the probability of oxygen reacting with the film layer as much as possible by segmenting and optimizing the process during growth, so as to reduce the degree of etching on the surface of the film layer, thereby improving the surface roughness of silicon dioxide, and the surface roughness of the prepared silicon dioxide film layer is significantly reduced by 58.3% compared with the conventional method. Specifically, the present invention first fills the cavity with silane, and only introduces a small amount of oxygen, so that the excess silane reacts with oxygen to generate a mixture of silicon monoxide and silicon dioxide, and forms an isolation layer on the carbon-containing film layer to isolate oxygen from reacting with the carbon-containing film layer, thereby avoiding oxygen oxidative corrosion of the carbon-containing film layer, and keeping the surface of the carbon-containing film layer as flat as possible, so that the subsequent silicon dioxide layer can grow on a relatively flat surface, and finally a silicon dioxide film layer with low surface roughness is generated on the carbon-containing film layer. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 A flow chart of a method for depositing a low-roughness silicon dioxide film on a carbon-containing film layer according to the present invention;
[0022] Figure 2 It is a curve diagram of the change of the refractive index of the oxygen-silicon film layer and the flow ratio;
[0023] Figure 3 AFM image showing a silicon dioxide film layer grown on the surface of a carbon-containing film layer using a conventional method;
[0024] Figure 4 This is an AFM image of the silicon dioxide film layer prepared in the ICP mode in Example 2;
[0025] Figure 5 This is an AFM image of the silicon dioxide film layer prepared in the PE-CVD mode in Example 2. DETAILED DESCRIPTION
[0026] Embodiment 1:
[0027] A method for depositing a low-roughness silicon dioxide film on a carbon-containing film layer comprises the following steps:
[0028] In the first step, after placing the wafer with a carbon film layer on the surface into the reaction chamber, the temperature of the reaction chamber is adjusted to 130°C, the growth temperature of silicon dioxide. At this time, the wafer is gradually heated from room temperature to 130°C, and then kept warm. During the heat preservation process, silane gas is introduced so that the interior of the reaction chamber is first filled with a large amount of silane gas.
[0029] The second step is to introduce oxygen at a low flow rate after heat preservation, and set the power of the plasma generator to 150 W. This allows the oxygen to be reacted with the excess silane in the chamber as much as possible, and a mixture of silicon monoxide and silicon dioxide is generated on the carbon-containing film layer, which serves as an isolation layer to isolate the carbon-containing film layer from the oxygen in the chamber.
[0030] The third step is to increase the flow rate of oxygen after the isolation layer is generated by a short reaction in the early stage. On the one hand, silicon dioxide is generated on the isolation layer. On the other hand, the excess oxygen oxidizes the isolation layer into stable silicon dioxide, and finally forms a silicon dioxide film layer with good density on the carbon-containing film layer. Finally, turn off the plasma generator first, then turn off the flow control valve of the precursor, and finally reduce the wafer temperature to room temperature, and the film growth process is completed.
[0031] like Figure 2 As shown, the present invention uses different flow ratios to complete the film growth on multiple 8-inch wafers, and then uses an ellipsometer to test the refractive index of each wafer. Each wafer tests 49 points, and the maximum value and average value of the 49 points are taken as the refractive index test data of the wafer. After that, the refractive index data of all wafers are sorted and plotted into a curve graph. For the generated isolation layer, we conducted a large number of experiments on different flow ratios (oxygen: silane) and characterized the refractive index of the grown film layer. The refractive indices of silicon monoxide film and silicon dioxide film are 1.96 and 1.45, respectively. When the flow ratio is lower than 0.19, that is, when there is a small amount of oxygen, both silicon monoxide and silicon dioxide are generated, and as the proportion of oxygen decreases, the refractive index will increase, that is, the higher the content of silicon monoxide. In the second step of the present invention, the flow ratio of oxygen to silane is 0.125-0.16, which is lower than 0.19, so the grown film layer is a mixture of silicon monoxide and silicon dioxide. When the flow ratio is greater than 0.19, silica is stably generated.
[0032] Compared with the general silicon dioxide film growth method, the biggest feature of the present invention is: first fill the cavity with silane, and only introduce a small amount of oxygen, so that the excess silane reacts with oxygen to generate a mixture of silicon monoxide and silicon dioxide, and forms an isolation layer on the carbon-containing film layer to isolate oxygen from reacting with the carbon-containing film layer, thereby avoiding oxygen oxidative corrosion of the carbon-containing film layer, and keeping the surface of the carbon-containing film layer as flat as possible, so that the subsequent silicon dioxide layer can grow on a relatively flat surface, and finally a silicon dioxide film layer with low surface roughness is generated on the carbon-containing film layer.
[0033] Embodiment 2:
[0034] A method for depositing a low-roughness silicon dioxide film on a carbon-containing film layer, using an ICP-CVD device, the process parameters are shown in Table 1, such as Figure 1 As shown, the specific steps include:
[0035] The first step is to place the wafer with a carbon film layer on the surface into the reaction chamber, adjust the temperature of the reaction chamber, and gradually heat the wafer from room temperature to 130°C. After the temperature reaches 130°C, keep it warm for 60 seconds to ensure that the entire wafer has a uniform temperature distribution. During the 60-second waiting process, the control valve of the silane precursor is opened through the control software, and silane is introduced into the reaction chamber at a flow rate of 60-64sccm. The purpose is to allow silane to enter the chamber in advance, so that the oxygen introduced later can react with silane as soon as possible, reducing the probability of oxygen reacting with the mask.
[0036] The second step is to keep the temperature for 60 seconds, then open the control valve of the oxygen precursor through the control software, and introduce oxygen into the reaction chamber at a flow rate of 8-10sccm. At the same time, the pressure in the reaction chamber is stabilized at 1.5Pa using the control software, and the power of the plasma generator is set to 150W. At this time, the flow rate of oxygen is low, so that the oxygen can be reacted with the excess silane in the chamber as much as possible to generate a film layer of a mixture of silicon monoxide and silicon dioxide, which serves as an isolation layer to isolate the carbon-containing film layer from the oxygen in the chamber, reducing the probability of the reaction between oxygen and the carbon-containing film layer.
[0037] The third step is to wait for the reaction for 30 seconds, and then adjust the control valve of the oxygen precursor through the control software to increase the flow rate of oxygen to 13-16sccm, so that the flow ratio is greater than 0.19, thereby stably generating silicon dioxide. At the same time, under this ratio, oxygen will show an excessive trend. By taking advantage of the fact that silicon monoxide is easily oxidized to silicon dioxide, the mixture of silicon monoxide and silicon dioxide in the second step is gradually transformed into a silicon dioxide film layer, which has good density and better isolates the carbon-containing film layer from the oxygen in the cavity.
[0038] Step 4: After waiting for 80 seconds, the film thickness gradually reaches the target thickness, which is 20nm. After that, the control software turns off the plasma generator, then the flow control valve of the precursor, and finally lowers the wafer temperature to room temperature, and the film growth process ends.
[0039] A silicon dioxide film layer was grown on the carbon-containing film layer using a conventional method as a comparative test group, that is, a silicon dioxide film layer of the same thickness was grown at a plasma power of 500 W using only the oxygen-silane flow ratio greater than 0.19. Figure 3 As shown, the roughness of the surface is characterized by using an atomic force microscope. The film layer containing carbon elements is largely etched and consumed by oxygen, and the mean square value of the roughness of the prepared silicon dioxide film layer is Rq=1.21nm.
[0040] The equipment used in this embodiment is ICP-CVD. In this embodiment, the carbon-containing film layer is first reacted for 30 seconds to form an isolation layer composed of a mixture of silicon monoxide and silicon dioxide, and then reacted for another 80 seconds to finally form a 20nm thick silicon dioxide film layer on the carbon-containing film layer. Figure 4 As shown, the surface roughness is also characterized by atomic force microscopy. The mean square value of the roughness of the prepared silicon dioxide film layer is Rq=0.504 nm. The surface roughness of the prepared silicon dioxide film layer is significantly reduced by 58.3% compared with the conventional method.
[0041] The device used in this embodiment is ICP-CVD. Since the device has both an ICP plasma generator and a radio frequency plasma generator, the device can be used as an ICP-CVD device or a PE-CVD device. The experimental results in this embodiment are experimental results under the ICP mode.
[0042] If the PE-CVD mode is used, the method in this embodiment is also used to grow a silicon dioxide film layer on the film layer containing carbon elements, such as Figure 5 As shown, the surface roughness of silicon dioxide is also characterized by atomic force microscopy, and the mean square roughness value of the prepared silicon dioxide film layer is Rq = 0.749nm. Figure 4 and Figure 5 It can be clearly seen that the roughness of silicon dioxide grown in PE-CVD mode is higher than that in ICP-CVD mode. Due to the limitation of equipment types, it cannot be verified on conventional PE-CVD equipment, so this conclusion only represents the growth results under different working modes of current ICP-CVD. However, from the growth principle, in theory, PE-CVD can also use this method to grow low-roughness silicon dioxide films on films containing carbon elements.
[0043] Table 1
[0044]
[0045] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the present invention.
Claims
1. A method for depositing a low-roughness silicon dioxide film on a carbon-containing film layer, characterized in that: The following steps are involved: Step S1: generating an isolation layer on the carbon-containing film layer: placing the carbon-containing film layer in a reaction chamber, first introducing silane into the reaction chamber, and then introducing oxygen, wherein the flow ratio of oxygen to silane is 0.125-0.16:1, setting the power of the plasma generator to 150W, and generating an isolation layer on the carbon-containing film layer; Step S2: generating a silicon dioxide film layer of target thickness on the carbon-containing film layer based on the isolation layer: increasing the flow rate of oxygen, and the flow rate ratio of oxygen to silane is greater than 0.19, while continuously generating silicon dioxide on the isolation layer, promoting the isolation layer to be oxidized into a silicon dioxide film layer.
2. A method for depositing a low-roughness silicon dioxide film on a carbon-containing film layer according to claim 1, characterized in that: In the step S1, the flow rate of the silane is 60-64 sccm, and the flow rate of the oxygen is 8-10 sccm.
3. A method for depositing a low-roughness silicon dioxide film on a carbon-containing film layer according to claim 2, characterized in that: In step S2, the flow rate of oxygen is 13-16 sccm.
4. A method for depositing a low-roughness silicon dioxide film on a carbon-containing film layer according to claim 1, characterized in that: In the step S1, the temperature of the reaction chamber is first gradually raised to 130° C., and while the reaction chamber is kept still and kept warm, silane is introduced into the rear of the reaction chamber.
5. A method for depositing a low-roughness silicon dioxide film on a carbon-containing film layer according to claim 4, characterized in that: In the step S1, while oxygen is introduced, the pressure of the reaction chamber is controlled to 1.5 Pa.
6. A method for depositing a low-roughness silicon dioxide film on a carbon-containing film layer according to claim 1, characterized in that: In the step S2, the flow ratio of oxygen to silane is 0.2-0.26:
1.
7. A method for depositing a low-roughness silicon dioxide film on a carbon-containing film layer according to any one of claims 1 to 6, characterized in that: Applied to generate a silicon dioxide film with a thickness of 10-40nm, comprising the following steps: Step A1: After placing a wafer having a carbon film layer on its surface into a reaction chamber, gradually heating the reaction chamber from room temperature to 130° C., and then keeping the temperature for 30-90 seconds to ensure that the entire wafer has a uniform temperature distribution; during the heat preservation process, silane is introduced into the reaction chamber at a flow rate of 60-64 sccm; Step A2: After heat preservation, oxygen is introduced into the reaction chamber at a flow rate of 8-10 sccm, and the pressure in the reaction chamber is stabilized at 1.5 Pa, and the power of the plasma generator is set to 150 W, and the reaction is carried out for 15-60 seconds to form an isolation layer on the carbon-containing film layer; Step A3: Then, the flow rate of oxygen is increased to 13-16 sccm, so that the flow rate ratio of oxygen to silane is greater than 0.19, so as to form a silicon dioxide film layer on the isolation layer and promote the isolation layer to be oxidized into a silicon dioxide film layer.
8. A method for depositing a low-roughness silicon dioxide film on a carbon-containing film layer according to claim 7, characterized in that: In the step A3, the reaction lasts for 80 seconds, and finally a silicon dioxide film layer with a thickness of 20 nm is generated on the carbon-containing film layer.