Method for carrying out gap filling by using TEOS (tetraethyl orthosilicate) film

Abstract

The invention provides a method for gap filling by using a TEOS film, which comprises the following steps: S1, placing a substrate with a gap to be filled in a PECVD (Plasma Enhanced Chemical Vapor Deposition) deposition chamber, heating the substrate to a preset temperature, introducing TEOS with a flow rate of 0.4 g / min-2. 0g / min and oxygen with a flow rate of 500 sccm to 3000 sccm into the deposition chamber, maintaining a preset pressure in the deposition chamber, starting a high-frequency power supply and a low-frequency power supply, and carrying out gap filling by using the TEOS film; depositing a silicon oxide film on the surface of the substrate after a preset first duration; s2, adjusting the flow of TEOS to be less than 0.4 g / min, and enabling the plasma in the deposition chamber to generate an etching effect on the surface of the substrate after a preset second duration; and S3, TEOS and oxygen are continuously introduced into the deposition chamber, and the silicon oxide film is continuously deposited on the surface of the substrate after a preset third duration. According to the method, the growth speed of the silicon oxide film can be ensured while the void defect of gap filling can be effectively avoided, and the production cost can be reduced while the production yield is improved. And operation is convenient, and damage to equipment is small.

Description

Technical Field

[0001] The invention relates to the technical field of integrated circuit manufacturing, and in particular to a method for gap filling using a TEOS film. Background Art

[0002] Plasma Enhance Chemical Vapour Deposition (PECVD) applies plasma to chemical vapor deposition, which can enable deposition to be carried out at a lower temperature and reduce the dependence of deposition on temperature. In the mixed gas composed of precursors and necessary gases, plasma glow discharge produces active radicals, which pass through the sheath and boundary layer above the substrate and adsorb to the substrate surface, diffuse and migrate and undergo chemical reactions, nucleate, island and film, and reaction byproducts desorb from the substrate surface, pass through the sheath and boundary layer and return to the main gas flow area, thus completing PECVD film deposition. PECVD TEOS (Tetraethyl Orthosilicate) film is a silicon oxide film, which uses TEOS as a silicon precursor, inert gases such as helium or argon as TEOS carrier gas, and oxygen as an oxidant to form a mixed gas, which is passed into the chamber and maintained at a certain pressure. High-frequency power and low-frequency power are used to jointly excite plasma to deposit silicon oxide film on the heated substrate surface.

[0003] Gap fill is a common semiconductor process, such as shallow trench isolation (STI), inter metal dielectric (IMD), and package trench filling. In the prior art, trench filling often uses high-density plasma chemical vapor deposition (HDPCVD) or high aspect ratio process (HARP), but these processes have high requirements on equipment, and the corresponding equipment is usually expensive. In comparison, PECVD equipment is not expensive, but the existing PECVD TEOS process is generally difficult to meet the gap filling requirements. It is easy to produce void defects when used to fill the gap, and there are problems such as low filling efficiency.

[0004] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present invention and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because these solutions are described in the background technology section of the present invention. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a method for gap filling using TEOS film, so as to solve the problems that the existing PECVD TEOS process is generally difficult to meet the gap filling requirements, it is easy to produce void defects when used to fill the gap, and there is a problem of low filling efficiency.

[0006] To achieve the above object and other related objects, the present invention provides a method for gap filling using a TEOS film, comprising the steps of:

[0007] S1: placing a substrate with a gap to be filled in a PECVD deposition chamber, heating the substrate to a preset temperature, introducing TEOS with a flow rate of 0.4 g / min to 2.0 g / min and oxygen with a flow rate of 500 sccm to 3000 sccm into the deposition chamber, turning on a high-frequency power supply and a low-frequency power supply to maintain a preset pressure in the deposition chamber, and depositing a silicon oxide film on the surface of the substrate after a preset first time period;

[0008] S2: adjusting the flow rate of TEOS to less than 0.4 g / min, and allowing the plasma in the deposition chamber to produce an etching effect on the substrate surface for a preset second time period;

[0009] S3: TEOS and oxygen are continuously introduced into the deposition chamber, and after a preset third time period, a silicon oxide film is continuously deposited on the surface of the substrate.

[0010] The second time duration is less than the first time duration and less than the third time duration, and the flow rates of TEOS and oxygen in step S3 are both greater than the flow rates in step S1.

[0011] Optionally, in step S1 to step S3, the substrate temperature is 75° C.-500° C., the power of the high-frequency power supply is 400W-1000W, and the power of the low-frequency power supply is 50W-500W.

[0012] Optionally, in step S1 and step S2, the pressure in the deposition chamber is 2 Torr-10 Torr; and in step S3, the pressure in the deposition chamber is 4 Torr-20 Torr.

[0013] More optionally, in step S1 to step S3, the substrate temperature is 150° C.-300° C., the power of the high-frequency power supply is 600W-800W, and the power of the low-frequency power supply is 100W-300W.

[0014] Optionally, in step S1 to step S3, the carrier gas of TEOS is argon and / or helium, and the carrier gas flow rate is 3000 sccm-10000 sccm.

[0015] Optionally, the flow rate of TEOS in step S2 is zero.

[0016] Optionally, after completing step S1, turn off the high-frequency power supply and the low-frequency power supply until the gas and pressure required for step S2 are stabilized, and then reload the power supply.

[0017] Optionally, the gap has an aspect ratio less than 7.

[0018] Optionally, the method includes looping step S1 and step S2 at least once, and then executing step S3.

[0019] Optionally, in step S3, the TEOS flow rate is 2.0 g / min to 10.0 g / min, and the oxygen flow rate is 1000 sccm to 10000 sccm.

[0020] Optionally, step S2 also includes a step of increasing power supply power.

[0021] As described above, the method of gap filling using TEOS film of the present invention has the following beneficial effects: the optimized process and process parameter design of the present invention can adjust the growth rate of silicon oxide film on PECVD equipment by only adjusting the flow rate of reaction source materials, especially by adjusting the flow rate of TEOS. During the adjustment process, the morphology of silicon oxide film at the upper part of the gap is modified by physical etching to avoid the upper part of the gap opening from closing too quickly, which can effectively avoid the void defects of gap filling while ensuring the growth rate of silicon oxide film, which helps to reduce production cost while improving production yield. In addition, the method provided by the present invention is easy to operate, requires few parameters to be adjusted, and causes less damage to the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 An exemplary flow chart of a method for gap filling using a TEOS film provided by the present invention is shown.

[0023] Figure 2 It is a schematic cross-sectional view of the structure obtained after executing step S1 in an embodiment of the present invention.

[0024] Figure 3 It is a schematic cross-sectional view of the structure obtained after executing step S2 in an embodiment of the present invention.

[0025] Figure 4 It is a schematic cross-sectional view of the structure obtained after executing step S3 in an embodiment of the present invention.

[0026] Figure 5 Shown is a scanning electron microscope image of a cross section of a sample after gap filling in an embodiment of the present invention.

[0027] Figure 6 Shown is a scanning electron microscope image of a cross section of a sample after gap filling in a comparative example of the present invention. DETAILED DESCRIPTION

[0028] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. For example, when describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional view showing the device structure will not be partially enlarged according to the general proportion, and the schematic diagram is only an example, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0029] For ease of description, spatially relative terms such as "under", "below", "below", "below", "above", "on", etc. may be used herein to describe the relationship of one element or feature shown in the drawings to other elements or features. It will be understood that these spatially relative terms are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the drawings. In addition, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.

[0030] In the context of the present invention, a structure in which a first feature is described as being "above" a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0031] It should be noted that the diagrams provided in this embodiment are only schematic illustrations of the basic concept of the present invention, and the diagrams only show the components related to the present invention rather than the number, shape and size of the components in actual implementation. The type, quantity and proportion of each component in actual implementation may be changed at will, and the layout of the components may also be more complicated. In order to make the diagrams as concise as possible, not all structures are marked in the drawings.

[0032] Gap filling is a common process in the manufacture of semiconductor devices, and its common defect is void. The main reason for the void is that the upper edge of the groove or hole is closed too early, forming a closed space, which prevents subsequent particles from entering the gap. Delaying the premature closure of the upper edge requires a smaller deposition rate and the ability to etch the film on the upper edge in time. One existing method is to use HDP CVD (high-density plasma chemical vapor deposition) equipment for deposition. Although HDP CVD can etch while depositing a thin film, HDP CVD requires the generation of high-density plasma, and requires the use of inductive coupled plasma (ICP) or electron cyclotron resonance (ECR) plasma or helicon plasma, and loading a radio frequency power supply on the heater to generate self-bias. This type of equipment is complex in design and has a high equipment cost. Another method is to add a small amount of etching gas (such as fluorine-containing gas) during the film deposition process, control the reaction rate by depositing and etching, and correct the film morphology, thereby achieving the purpose of reducing void defects. However, this method of adding etching reaction gas can easily pollute the cavity and the process is difficult to control.

[0033] To this end, this case proposes a method for efficiently depositing high-quality TEOS films in a gap based on PECVD equipment.

[0034] Specifically, the present invention proposes a method for gap filling using a TEOS film. More specifically, the present invention provides a method for gap filling using a PECVD TEOS film process. The general process can be referred to Figure 1As shown. That is, the thin film deposition process involved in the present invention is implemented in a PECVD chamber. The deposition chamber used generally includes a metal cavity, a gas spray plate located at the top of the deposition chamber, and a base located inside the deposition chamber and usually directly below the gas spray plate. The deposition chamber can be a cavity made of metal materials such as aluminum alloy or stainless steel, and the inner wall can be plated with a corrosion-resistant coating such as ceramic. The base can fix the substrate to be deposited based on electrostatic adsorption and / or vacuum adsorption. Heating and / or cooling pipelines can be provided inside the base to adjust the substrate temperature as needed. As needed, during the deposition process, the base can be rotated and / or raised and lowered, which helps to improve the uniformity of deposition. The gas spray plate can be a conductive material such as graphite or aluminum, which is electrically connected to a radio frequency power supply. In this embodiment, a high-frequency power supply and a low-frequency power supply are applied to the gas spray plate at the same time, which is a dual-power excitation mode. The reaction gas is input into the interior of the deposition chamber through the pores of the gas spray plate. Under the action of the electric field excited by the radio frequency power supply, the reaction gas decomposes into electrons, ions and active groups, and is deposited into a film on the substrate surface under corresponding deposition conditions.

[0035] Next, the present invention will be further described in conjunction with the accompanying drawings.

[0036] First, step S1 is performed to place the substrate 11 having the gap 12 to be filled in a PECVD deposition chamber. After the substrate 11 is heated to a preset temperature, TEOS with a flow rate of 0.4 g / min to 2.0 g / min and oxygen with a flow rate of 500 sccm to 3000 sccm are introduced into the deposition chamber to maintain a preset pressure in the deposition chamber. The high-frequency power supply and the low-frequency power supply are turned on. After a preset first period of time, a silicon oxide film 13 is deposited on the surface of the substrate 11, including the surface of the gap.

[0037] The substrate 11 may be a wafer of semiconductor materials such as silicon, silicon on insulator, silicon carbide, sapphire, etc., or may be a substrate of other materials or other shapes such as glass. In this embodiment, the deposition of the substrate 11 of a 12-inch silicon wafer is taken as an example. The gap 12 may be a groove, a pore or other groove structure formed on the substrate 11 by processes such as photolithography and etching, and its cross-section may be a rectangular or trapezoidal structure. The depth-to-width ratio of the gap 12 is preferably within 10, for example, the depth-to-width ratio is less than 7. The present invention is particularly suitable for filling gaps with a depth-to-width ratio of 1.5-6. The number of gaps 12 may be more than one, and the arrangement thereof may also be determined according to needs. For example, if it is a shallow trench structure for isolation, the gaps 12 are usually arranged in an array. The substrate 11 is usually cleaned before being placed in the deposition chamber. For example, DHF cleaning is first used to remove the natural oxide film and metal particle impurities on the surface, and then it is cleaned with deionized water, and then dried. After being placed in the deposition chamber, the wafer surface may also be cleaned again by nitrogen purging or the like.

[0038] After ensuring that the cleanliness of the substrate 11 meets the requirements, the substrate 11 is heated to reach a preset temperature. The heating method can be to heat the wafer by a heater that carries the wafer, or to heat the wafer by introducing a heated inert gas into the chamber. In this embodiment, the former is adopted, that is, the wafer is directly heated by a heater that carries the wafer, and the wafer temperature can be monitored in real time by a thermocouple arranged in the deposition chamber to adjust as needed. In a preferred embodiment, in order to reduce the preheating time and improve the equipment utilization rate, the substrate can be placed in the deposition chamber after being heated to a preset temperature in the deposition chamber (the substrate can also be preheated outside the deposition chamber before being placed in the deposition chamber). In this embodiment, the heating temperature of the substrate 11 is set at 75°C-500°C, preferably 150°C-300°C, for example, 150, 200, 250, 300 or any value in this range. After being heated to the required temperature, TEOS and oxygen are introduced into the deposition chamber, and a high-frequency power supply and a low-frequency power supply are loaded on the gas spray plate at the top of the deposition chamber, and the high and low frequencies can be determined according to the equipment. For example, in this embodiment, a 13.56MHz high-frequency power supply and a 400KHz power supply are used, and the power of the high-frequency power supply is 400W~1000W, and the power of the low-frequency power supply is 50W~500W. In a more preferred example, the power of the high-frequency power supply is 600W~800W, for example, 600, 700, 800 or any value in this range; the power of the low-frequency power supply is 100W~300W, for example, 100, 150, 200, 250, 300 or any value in this range.

[0039] In the present invention, the flow rate of the reaction material source is a very important parameter, and the deposition rate of the film 13 is regulated by adjusting the flow rate of the reaction material. In step S1, the flow rate of TEOS is set to 0.4 g / min~2.0 g / min, and the flow rate of oxygen is set to 500 sccm~3000 sccm. Such a flow setting can make the deposition of the silicon oxide film 13 at a relatively slow rate, avoiding the silicon oxide film 13 from growing too fast and causing the upper part of the gap 12 to be deposited too fast, especially avoiding the premature closure of the opening of the gap 12. TEOS is preferably transported by a carrier gas, and the carrier gas is, for example, argon and / or nitrogen (preferably a single gas), and the carrier gas flow rate is 3000 sccm~10000 sccm. The pressure in the chamber is maintained at 2 Torr~10Torr, for example, 4 Torr-6Torr. In the preferred example provided by the present invention, the gas can be introduced first, and the power supply can be loaded after the pressure in the chamber is stable, which helps to control the process. In other examples, the gas and the power supply can also be carried out almost simultaneously, and there is no strict restriction on this.

[0040] The execution time of this step is determined according to factors such as the thickness of the film 13 to be grown and the aspect ratio of the gap 12. Preferably, the thickness of the film 13 grown in this step is controlled within one-third of the total film thickness, and in particular, it is necessary to ensure that the film 13 in the gap 12 does not close the top opening of the gap 12. For example, after step S1, the opening size of the gap 12 is still not less than one-third of its initial opening size. Although the growth rate of the film 13 is controlled at a lower level by controlling the gas flow rate in this step, due to the growth characteristics of the film 13 in the gap 12, the film 13 in the gap 12 still presents a situation where the upper deposition thickness is greater than the thickness of the lower part and the bottom. The general structure can be referred to. Figure 2 As shown, it can be seen that the opening at the top of the gap is already very small, and it is very difficult to continue filling it according to the existing process, and the process needs to be adjusted to modify the growing film 13.

[0041] To this end, the present invention adds step S2, adjusting the flow rate of TEOS to less than 0.4 g / min. When the flow rate of TEOS is adjusted to less than this value, the plasma in the deposition chamber will produce an etching effect on the surface of the substrate 11 and modify the existing deposited silicon oxide film. After the preset second time period, the film at the top of the gap will be thinned, so that the opening at the top of the gap is enlarged, which is convenient for subsequent high-speed deposition. And this etching is purely physical etching, and no new impurities will be introduced.

[0042] In step S2, the deposition rate of silicon oxide can be reduced by reducing the flow rate of TEOS, or even directly reduced to zero, while keeping other parameters unchanged (i.e., other parameters are the same as those in step S1, or only the TEOS flow rate is a variable), and the carrier gas and oxygen and other gases other than TEOS are still introduced normally according to the original parameters. Under the excitation of the radio frequency power supply, the carrier gas and other gases such as oxygen are excited to form plasma. Due to the lack of TEOS, the deposition reaction cannot be fully carried out, and the plasma in the chamber physically bombards the substrate 11 to produce an etching effect (the etching rate of the silicon oxide film is greater than the deposition rate), thereby etching and removing the silicon oxide film 13 formed in step S1. When the flow rate of TEOS is adjusted to less than 0.4g / min, the etching effect in the chamber gradually becomes obvious. When the flow rate of TEOS is controlled within 0.20g / min, the etching rate gradually increases. When the flow rate of TEOS is 0, the etching rate is the maximum. Through this step, part of the silicon oxide film 13 on the upper edge of the gap 12 is etched away to avoid the formation of a closed space inside the gap 12, that is, to avoid the formation of a void defect. The etching time of this step is less than the deposition time in step S1. Preferably, the time of this step is within half of the time in step S1, for example, 1 / 4-1 / 3 of the time in step S1. After this step, the silicon oxide film 13 in the gap 12 is corrected to a morphology with substantially the same thickness from top to bottom, presenting a structure such as Figure 3 shown. Figure 3 The dotted area in FIG. 1 roughly indicates the thin film 13 that is etched away in this step.

[0043] As mentioned above, the other parameters in this step are preferably the same as those in step S1, which can minimize the adjustment of parameters, simplify the process, and reduce the adverse effects on equipment and wafers. For example, in some examples, the temperature of the substrate 11 is 75°C-500°C, preferably 150°C-300°C; the power of the high-frequency power supply is 400W~1000W, preferably 600W~800W; the power of the low-frequency power supply is 50W~500W, preferably 100W~300W; the pressure in the deposition chamber is 2Torr-10Torr, preferably 4Torr -6Torr. In some examples, the carrier gas flow rate and oxygen flow rate of TEOS remain unchanged (even if the TEOS flow rate is zero, the carrier gas continues to be filled at the original flow rate). In other examples, for the purpose of cost reduction, the carrier gas flow rate of TEOS can be maintained unchanged, but the oxygen flow rate can be appropriately reduced. When the power supply power and the flow rates of other gases except TEOS in steps S1 and S2 remain unchanged, the flow rate of TEOS can be switched immediately, for example, from 0.5 g / min in step S1 to zero flow rate in step S2. This method is relatively simple to adjust. Another method is to adjust slowly, for example, first adjust from 0.5 g / min in step S1 to 0.2 g / min, and then adjust to zero after a period of time (for example, 5s-10s). This method helps to avoid plasma extinguishing and avoid damage to the equipment by frequently starting the power supply.

[0044] In some other examples, while reducing the TEOS flow rate in step S2, the power supply power can be increased at the same time (one or both of the high-frequency power supply and the low-frequency power supply power are increased) to increase the plasma energy and density and accelerate the etching of the silicon oxide film. In this case, the time of step S2 can be appropriately shortened.

[0045] In some examples, after completing step S1, the high-frequency power supply and the low-frequency power supply can be turned off first, so that the residual reaction gas in the deposition chamber cannot generate plasma, that is, the plasma supply is stopped, and the low-rate TEOS film 13 deposition is suspended until the original residual reaction gas is exhausted, and then new gas is introduced according to the parameters of step S2, until the gas and pressure required for step S2 are stable, and then the power supply is reloaded to ignite the plasma to perform the process of etching the upper edge TEOS film 13 in step S2. The advantage of this method is that the process time is more controllable.

[0046] After the etching in step S2, the morphology of the silicon oxide film 13 in the gap 12 is modified to the desired morphology, and then step S3 is performed to continue to introduce TEOS and oxygen into the deposition chamber. After a preset third time, the silicon oxide film 13 is continued to be deposited on the surface of the substrate 11.

[0047] This step is a high-speed growth stage of the TEOS film 13 (compared to the growth rate of step S1), so the required TEOS flow rate and oxygen flow rate, as well as the growth time of this step are greater than those of step S1. In some examples, the TEOS flow rate in this step is 2.0 g / min ~10.0 g / min, preferably 3.0 g / min ~5.0 g / min; the oxygen flow rate is 1000 sccm ~10000 sccm, preferably 3000 sccm-5000 sccm; the chamber pressure is preferably 4 Torr ~20 Torr. Preferably, in this step, except for the increase in TEOS and oxygen flow rates, other parameters are the same as those in step S1 and step S2, for example, the temperature of the substrate 11 is 75°C-500°C, preferably 150°C-300°C; the power of the high-frequency power supply is 400W-1000W, preferably 600W-800W; the power of the low-frequency power supply is 50W-500W, preferably 100W-300W; the carrier gas flow rate is 3000sccm-10000sccm. After step S3, the structure of the grown silicon oxide film 13 can be roughly referred to Figure 4 shown.

[0048] In some examples, when the gap 12 has a relatively large depth and / or a relatively large aspect ratio, step S3 may be performed after looping step S1 and step S2 at least once. For example, first looping step S1 and step S2 until the gap 12 is completely filled, and then performing step S3 until the deposition of the film 13 of the desired thickness is completed.

[0049] In some examples, if the lateral dimension of the gap is relatively large and the depth-to-width ratio of the gap is relatively small, steps S1 to S3 may be executed repeatedly.

[0050] In some examples, after completing step S3, the deposited film 13 may be passivated. For example, after completing step S3, nitrogen-containing gas (such as nitrogen or nitrous oxide) is introduced into the same deposition chamber while stopping the supply of TEOS to passivate the silicon oxide gas, which helps to further improve the quality of the film 13. Alternatively, passivation may be performed by heating (heating the substrate to a temperature higher than that during the deposition process).

[0051] In some other examples, after completing step S3, the formed thin film 13 may be subjected to a surface planarization process, or the thin film 13 may be passivated first and then subjected to a surface planarization process.

[0052] The method for gap filling using TEOS film provided in this embodiment can adjust the growth rate of silicon oxide film on PECVD equipment by only adjusting the flow rate of reaction source materials, especially by adjusting the flow rate of TEOS. During the adjustment process, the existing plasma is used to modify the morphology of silicon oxide film on the upper part of the gap based on the physical etching principle to avoid the upper part of the gap opening being closed too quickly. While effectively avoiding the void defects of gap filling, the growth rate of silicon oxide film can be ensured, which helps to reduce production costs while improving production yield. In addition, the method provided in this embodiment is easy to operate, requires fewer parameters to be adjusted, and causes less damage to the equipment.

[0053] In order to make the technical solutions and advantages of the present invention more prominent, the implementation of the present invention is described in more detail below through specific embodiments and comparative examples.

[0054] Example

[0055] The process conditions of step S1 are: substrate heating temperature is 200°C; TEOS flow rate is 0.5g / min; TEOS carrier gas is He, with a flow rate of 8000sccm, and an oxygen flow rate of 1000sccm; chamber pressure is 4.2Torr; HF power supply power is 760W, LF power supply power is 200W; and deposition time is 100s.

[0056] The process conditions of step S2 are: substrate heating temperature is 200°C; TEOS flow rate is 0 g / min, TEOS carrier gas is He, flow rate is 8000 sccm, oxygen flow rate is 1000 sccm; chamber pressure is 4.2 Torr; HF power supply power is 760 W, LF power supply power is 200 W; etching time is 30 s

[0057] The process conditions of step S3 are: substrate heating temperature is 200°C; TEOS flow rate is 3.5g / min, TEOS carrier gas is He, flow rate is 8000sccm, oxygen flow rate is 4000sccm; chamber pressure is 4.2Torr; HF power supply power is 760W, LF power supply power is 200W; deposition time is 165s.

[0058] In the specific execution process, the plasma is maintained from step S1 to step S2, and the parameters are switched immediately, that is, the TEOS flow rate is switched from 0.5 g / min to 0 g / min immediately, which is one cycle, and a total of 3 cycles are performed, and then step S3 is performed. When performing the cycle, there is also a process from step S2 to step S1, and this process also maintains the plasma and the parameters are switched immediately, that is, the TEOS flow rate is switched from 0 g / min to 0.5 g / min immediately.

[0059] The overall process is a combination of step S1, step S2 and step S3. The overall process process is (S1+S2)×3+S3, and the total film deposition thickness is about 1.6 microns.

[0060] The gap morphology filled in this example is reference Figure 5 As shown in the scanning electron microscope image. Figure 5 The dotted line in the figure is a trench with a depth-to-width ratio of 1.6:1 and a sidewall angle of 82°. It can be seen from the figure that there is no void in the filled trench.

[0061] On the basis of this example, a large number of experiments were conducted by adjusting the gas flow rate, power supply power, chamber pressure and other conditions. Since the experimental process and experimental results are basically similar, they will not be expanded one by one. A large number of experiments show that when the conditions proposed by the present invention are met, no obvious voids are seen in the gaps filled under different process conditions, indicating that the method of the present invention can effectively improve the void defects by using TEOS film to fill the gap.

[0062] Comparative Example

[0063] In the comparative example, only steps S1 and S3 of the present invention are performed.

[0064] The process conditions of step S1 are as follows: substrate heating temperature is 200°C; TEOS flow rate is 0.5 g / min, TEOS carrier gas is He, flow rate is 8000 sccm, oxygen flow rate is 1000 sccm; chamber pressure is 4.2 Torr; HF power supply power is 760 W, LF power supply power is 200 W; deposition time is 270 s;

[0065] The process conditions of step S3 are: substrate heating temperature is 200°C; TEOS flow rate is 3.5g / min, TEOS carrier gas is He, flow rate is 8000sccm, oxygen flow rate is 4000sccm; chamber pressure is 4.2Torr; HF power supply power is 760W, LF power supply power is 200W; deposition time is 165s.

[0066] In the comparative example, the overall process is a combination of step S1 and step S3, and the overall process is step S1 + step S3. Except that step S2 in the present invention is not performed, and the deposition time in step S1 is different from that in the embodiment (the deposition time is adjusted to deposit a film of the same thickness as in the embodiment), other parameters are the same as those in the embodiment. The total film deposition thickness deposited in the comparative example is about 1.6 microns, and the gap morphology filled is referenced Figure 6 As shown in the scanning electron microscope image. Figure 6 The dotted line marks the groove, the groove aspect ratio is 1.6:1, the side wall angle is 82°, and the arrow indicates the void. It can be seen that there are obvious voids in the filled groove.

[0067] A large number of comparative experiments similar to this comparative example show that, under the premise of completing the deposition of a thin film of the desired thickness, in the experiment where only steps S1 and S3 are performed, no matter how the deposition time of steps S1 and 3 are adjusted, voids exist in the filled gaps, especially the shorter the time of step S1 and the longer the time of S3 (other parameters except the execution time are the same as those of the present invention), the more obvious the voids become.

[0068] In summary, the method for gap filling using TEOS film disclosed in the present invention can be optimized through the design of process and process parameters. It can adjust the growth rate of silicon oxide film on PECVD equipment by only adjusting the flow rate of reaction source materials, especially by adjusting the flow rate of TEOS. During the adjustment process, the physical etching effect is used to modify the morphology of silicon oxide film on the upper part of the gap to avoid the upper part of the gap opening from closing too quickly. While effectively avoiding the void defects of gap filling, the growth rate of silicon oxide film can be ensured, and the production yield can be improved while reducing the production cost. The method provided by the present invention is easy to operate, requires fewer parameters to be adjusted, and causes less damage to the equipment. The present invention can be used for filling shallow trench isolation structures and preparing interlayer dielectric layers, and can be used for both front-end processes and back-end packaging processes. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has a high industrial utilization value.

[0069] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for gap filling using a TEOS film, characterized in that: Includes steps: S1: placing a substrate with a gap to be filled in a PECVD deposition chamber, heating the substrate to a preset temperature, introducing TEOS with a flow rate of 0.4 g / min to 2.0 g / min and oxygen with a flow rate of 500 sccm to 3000 sccm into the deposition chamber, maintaining a preset pressure in the deposition chamber, turning on a high-frequency power supply and a low-frequency power supply, and depositing a silicon oxide film on the surface of the substrate after a preset first time period; S2: adjusting the flow rate of TEOS to less than 0.4 g / min, and allowing the plasma in the deposition chamber to produce an etching effect on the substrate surface for a preset second time period; S3: TEOS and oxygen are continuously introduced into the deposition chamber, and a silicon oxide film is continuously deposited on the surface of the substrate after a preset third time period; The second time duration is less than the first time duration and less than the third time duration, and the flow rates of TEOS and oxygen in step S3 are both greater than the flow rates in step S1.

2. The method according to claim 1, characterized in that In steps S1 to S3, the substrate temperature is 75°C-500°C, the power of the high-frequency power supply is 400W~1000W, and the power of the low-frequency power supply is 50W~500W; in steps S1 and S2, the pressure in the deposition chamber is 2Torr-10Torr; in step S3, the pressure in the deposition chamber is 4Torr-20Torr.

3. The method according to claim 2, characterized in that In step S1 to step S3, the substrate temperature is 150° C.-300° C., the power of the high-frequency power supply is 600W-800W, and the power of the low-frequency power supply is 100W-300W.

4. The method according to claim 1, characterized in that: In step S1 to step S3, the carrier gas of TEOS is argon and / or helium, and the carrier gas flow rate is 3000 sccm-10000 sccm.

5. The method according to claim 1, characterized in that The flow rate of TEOS in step S2 is zero.

6. The method according to claim 1, characterized in that After completing step S1, turn off the high-frequency power supply and the low-frequency power supply until the gas and pressure required by step S2 are stable, and then reload the power supply.

7. The method according to claim 1, characterized in that The aspect ratio of the gap is less than 7.

8. The method according to claim 1, characterized in that The method comprises: performing step S3 after looping step S1 and step S2 at least once.

9. The method according to claim 1, characterized in that: The TEOS flow rate in step S3 is 2.0 g / min to 10.0 g / min, and the oxygen flow rate is 1000 sccm to 10000 sccm.

10. The method according to any one of claims 1 to 9, characterized in that: Step S2 also includes a step of increasing the power of the power supply.

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